chore: update AltStore source to v4.7.1

Replace duplicate genre/label-only embedding with a shared post-download
step that writes complete FLAC tags and optional cover art when the output
file is available locally.

.github/workflows/release.yml

@@ -66,7 +66,7 @@ jobs:
         uses: actions/setup-java@v5
         with:
           distribution: "temurin"
-          java-version: "17"
+          java-version: "25"
 
       - name: Setup Go
         uses: actions/setup-go@v6
@@ -257,6 +257,15 @@ jobs:
       - name: Get Flutter dependencies
         run: flutter pub get
 
+      - name: Normalize ffmpeg plugin shell scripts (strip CRLF)
+        run: |
+          find "$HOME/.pub-cache/hosted" -path "*ffmpeg_kit_flutter_new_full*/scripts/*.sh" -type f -print0 |
+            while IFS= read -r -d '' f; do
+              perl -pi -e 's/\r$//' "$f"
+              chmod +x "$f"
+              echo "Normalized line endings: $f"
+            done
+
       - name: Generate app icons
         run: dart run flutter_launcher_icons
 
@@ -379,8 +388,6 @@ jobs:
           ### Installation
           **Android**: Enable "Install from unknown sources" and install the APK
           **iOS**: Use AltStore, Sideloadly, or similar tools to sideload the IPA
-
-          ![arm64](https://img.shields.io/github/downloads/${REPO_OWNER}/${REPO_NAME}/${VERSION}/SpotiFLAC-${VERSION}-arm64.apk?style=flat-square&logo=android&label=arm64&color=3DDC84) ![arm32](https://img.shields.io/github/downloads/${REPO_OWNER}/${REPO_NAME}/${VERSION}/SpotiFLAC-${VERSION}-arm32.apk?style=flat-square&logo=android&label=arm32&color=3DDC84) ![iOS](https://img.shields.io/github/downloads/${REPO_OWNER}/${REPO_NAME}/${VERSION}/SpotiFLAC-${VERSION}-ios-unsigned.ipa?style=flat-square&logo=apple&label=iOS&color=0078D6)
           FOOTER
 
           echo "Release body:"
@@ -390,7 +397,7 @@ jobs:
         uses: softprops/action-gh-release@v2
         with:
           tag_name: ${{ needs.get-version.outputs.version }}
-          name: SpotiFLAC ${{ needs.get-version.outputs.version }}
+          name: SpotiFLAC-Mobile ${{ needs.get-version.outputs.version }}
           body_path: /tmp/release_body.txt
           files: ./release/*
           draft: false
@@ -556,7 +563,7 @@ jobs:
             curl -s -X POST "https://api.telegram.org/bot${TELEGRAM_BOT_TOKEN}/sendDocument" \
               -F chat_id="${TELEGRAM_CHANNEL_ID}" \
               -F document=@"${ARM64_APK}" \
-              -F caption="SpotiFLAC ${VERSION} - arm64 (recommended)"
+              -F caption="SpotiFLAC Mobile ${VERSION} - arm64 (recommended)"
           fi
 
           # Upload arm32 APK to channel
@@ -565,7 +572,7 @@ jobs:
             curl -s -X POST "https://api.telegram.org/bot${TELEGRAM_BOT_TOKEN}/sendDocument" \
               -F chat_id="${TELEGRAM_CHANNEL_ID}" \
               -F document=@"${ARM32_APK}" \
-              -F caption="SpotiFLAC ${VERSION} - arm32"
+              -F caption="SpotiFLAC Mobile ${VERSION} - arm32"
           fi
 
           # Upload iOS IPA to channel
@@ -575,7 +582,7 @@ jobs:
             curl -s -X POST "https://api.telegram.org/bot${TELEGRAM_BOT_TOKEN}/sendDocument" \
               -F chat_id="${TELEGRAM_CHANNEL_ID}" \
               -F document=@"${IOS_IPA}" \
-              -F caption="SpotiFLAC ${VERSION} - iOS (unsigned, sideload required)"
+              -F caption="SpotiFLAC Mobile ${VERSION} - iOS (unsigned, sideload required)"
           fi
 
           echo "Telegram notification sent!"

.gitignore

@@ -60,12 +60,15 @@ ios/Flutter/Flutter.framework/
 ios/Flutter/Flutter.podspec
 
 # Extension folder
-extension/
+extension/*
+extension/v2/
+extension/v2/**
 
 # Agent instructions
 AGENTS.md
 
 # Temp/misc
+.tmp/
 nul
 NUL
 network_requests.txt

README.md

@@ -59,7 +59,7 @@ Extensions let the community add new music sources and features without waiting
 ## Related Projects
 
 ### [SpotiFLAC (Desktop)](https://github.com/afkarxyz/SpotiFLAC)
-Download music in true lossless FLAC from Tidal, Qobuz & Amazon Music available for Windows, macOS & Linux.
+Download music in true lossless FLAC from extension-provided sources on Windows, macOS & Linux.
 
 ### [SpotiFLAC (Python Module)](https://github.com/ShuShuzinhuu/SpotiFLAC-Module-Version)
 Python library for SpotiFLAC integration, maintained by [@ShuShuzinhuu](https://github.com/ShuShuzinhuu).
@@ -80,7 +80,7 @@ Starting from version 3.8.0, SpotiFLAC uses a decentralized extension repository
 <summary><b>Why is my download failing with "Song not found"?</b></summary>
 <br>
 
-The track may not be available on the streaming services. Try enabling more providers under **Settings > Download > Provider Priority**, or install additional extensions like Amazon Music from the Store.
+The track may not be available from your enabled providers. Try enabling more providers under **Settings > Extensions > Provider Priority**, or install additional download extensions from the Store.
 
 </details>
 
@@ -88,10 +88,7 @@ The track may not be available on the streaming services. Try enabling more prov
 <summary><b>Why are some tracks downloading in lower quality?</b></summary>
 <br>
 
-Quality depends on what's available from the streaming service and its extensions. Built-in providers:
-- **Tidal** up to 24-bit/192kHz
-- **Qobuz** up to 24-bit/192kHz
-- **Deezer** up to 16-bit/44.1kHz
+Quality depends on what's available from the source and the installed download extension. Check each extension's quality options and service notes in the app.
 
 </details>
 

android/app/build.gradle.kts

@@ -17,7 +17,7 @@ if (keystorePropertiesFile.exists()) {
 
 android {
     namespace = "com.zarz.spotiflac"
-    compileSdk = flutter.compileSdkVersion
+    compileSdk = 37
     ndkVersion = flutter.ndkVersion
 
     buildFeatures {
@@ -26,13 +26,13 @@ android {
 
     compileOptions {
         isCoreLibraryDesugaringEnabled = true
-        sourceCompatibility = JavaVersion.VERSION_17
-        targetCompatibility = JavaVersion.VERSION_17
+        sourceCompatibility = JavaVersion.VERSION_25
+        targetCompatibility = JavaVersion.VERSION_25
     }
 
     kotlin {
         compilerOptions {
-            jvmTarget.set(org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_17)
+            jvmTarget.set(org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_25)
         }
     }
 
@@ -50,7 +50,7 @@ android {
     defaultConfig {
         applicationId = "com.zarz.spotiflac"
         minSdk = flutter.minSdkVersion
-        targetSdk = 36
+        targetSdk = 37
         versionCode = flutter.versionCode
         versionName = flutter.versionName
         multiDexEnabled = true
@@ -62,6 +62,8 @@ android {
 
     buildTypes {
         getByName("debug") {
+            applicationIdSuffix = ".debug"
+            versionNameSuffix = "-debug"
             ndk {
                 debugSymbolLevel = "FULL"
             }

android/app/src/main/AndroidManifest.xml

@@ -100,6 +100,12 @@
                 <category android:name="android.intent.category.BROWSABLE" />
                 <data android:scheme="spotiflac" android:host="spotify-callback" />
             </intent-filter>
+            <intent-filter>
+                <action android:name="android.intent.action.VIEW" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <category android:name="android.intent.category.BROWSABLE" />
+                <data android:scheme="spotiflac" android:host="session-grant" />
+            </intent-filter>
         </activity>
 
         <!-- Download Service -->
@@ -108,6 +114,23 @@
             android:exported="false"
             android:foregroundServiceType="dataSync" />
 
+        <service
+            android:name="com.ryanheise.audioservice.AudioService"
+            android:foregroundServiceType="mediaPlayback"
+            android:exported="true"
+            android:enabled="true">
+            <intent-filter>
+                <action android:name="android.media.browse.MediaBrowserService" />
+            </intent-filter>
+        </service>
+        <receiver
+            android:name="com.ryanheise.audioservice.MediaButtonReceiver"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.MEDIA_BUTTON" />
+            </intent-filter>
+        </receiver>
+
         <!-- flutter_local_notifications receivers -->
         <receiver android:exported="false" android:name="com.dexterous.flutterlocalnotifications.ScheduledNotificationReceiver" />
         <receiver android:exported="false" android:name="com.dexterous.flutterlocalnotifications.ScheduledNotificationBootReceiver">
@@ -124,6 +147,10 @@
             android:name="flutterEmbedding"
             android:value="2" />
 
+        <meta-data
+            android:name="com.google.android.gms.car.application"
+            android:resource="@xml/automotive_app_desc" />
+
         <!-- FileProvider for APK installation -->
         <provider
             android:name="androidx.core.content.FileProvider"

android/app/src/main/kotlin/com/zarz/spotiflac/MainActivity.kt

@@ -1,6 +1,7 @@
 package com.zarz.spotiflac
 
 import android.app.Activity
+import android.content.Context
 import android.content.Intent
 import android.net.Uri
 import android.os.Build
@@ -17,6 +18,7 @@ import io.flutter.embedding.engine.FlutterEngine
 import io.flutter.embedding.engine.FlutterShellArgs
 import io.flutter.plugin.common.EventChannel
 import io.flutter.plugin.common.MethodChannel
+import com.ryanheise.audioservice.AudioServicePlugin
 import gobackend.Gobackend
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
@@ -36,6 +38,10 @@ import java.security.MessageDigest
 import java.util.Locale
 
 class MainActivity: FlutterFragmentActivity() {
+    override fun provideFlutterEngine(context: Context): FlutterEngine {
+        return AudioServicePlugin.getFlutterEngine(context)
+    }
+
     private val CHANNEL = "com.zarz.spotiflac/backend"
     private val DOWNLOAD_PROGRESS_STREAM_CHANNEL =
         "com.zarz.spotiflac/download_progress_stream"
@@ -47,6 +53,8 @@ class MainActivity: FlutterFragmentActivity() {
     private val LARGE_JSON_RESULT_FILE_KEY = "__json_file"
     private val LARGE_JSON_RESULT_FILE_THRESHOLD_BYTES = 256 * 1024
     private val scope = CoroutineScope(SupervisorJob() + Dispatchers.Main)
+    private var backendChannel: MethodChannel? = null
+    private val pendingSessionGrantEvents = mutableListOf<Map<String, Any>>()
     private var pendingSafTreeResult: MethodChannel.Result? = null
     private val safScanLock = Any()
     private val safDirLock = Any()
@@ -148,8 +156,15 @@ class MainActivity: FlutterFragmentActivity() {
             "mali-t7",
             "powervr sgx",
             "powervr ge8320",
+            "vivante",
             "gc1000",
             "gc2000",
+            "gc4000",
+            "gc5000",
+            "gc7000",
+            "gc8000",
+            "gc820",
+            "gc880",
         )
 
         private val PROBLEMATIC_CHIPSETS = listOf(
@@ -163,6 +178,15 @@ class MainActivity: FlutterFragmentActivity() {
             "apq8084",
         )
 
+        // Sony Walkman / audio players report MANUFACTURER "SonyAudio" (distinct
+        // from Xperia phones, which use "Sony"). They ship legacy Vivante GPUs
+        // whose drivers crash in glLinkProgram with Impeller shaders, and the GL
+        // renderer string is unavailable when shell args are built, so match on
+        // the manufacturer instead.
+        private val PROBLEMATIC_MANUFACTURERS = listOf(
+            "sonyaudio",
+        )
+
         private val PROBLEMATIC_MODELS = listOf(
             "sm-t220",
             "sm-t225",
@@ -173,6 +197,14 @@ class MainActivity: FlutterFragmentActivity() {
             val board = Build.BOARD.lowercase(Locale.ROOT)
             val model = Build.MODEL.lowercase(Locale.ROOT)
             val device = Build.DEVICE.lowercase(Locale.ROOT)
+            val manufacturer = Build.MANUFACTURER.lowercase(Locale.ROOT)
+
+            for (problematicManufacturer in PROBLEMATIC_MANUFACTURERS) {
+                if (manufacturer.contains(problematicManufacturer)) {
+                    android.util.Log.i("SpotiFLAC", "Matched problematic manufacturer: $problematicManufacturer")
+                    return true
+                }
+            }
 
             for (problematicModel in PROBLEMATIC_MODELS) {
                 if (model.contains(problematicModel) || device.contains(problematicModel)) {
@@ -307,6 +339,8 @@ class MainActivity: FlutterFragmentActivity() {
             ".mp3" -> "audio/mpeg"
             ".opus" -> "audio/ogg"
             ".flac" -> "audio/flac"
+            ".wav" -> "audio/wav"
+            ".aiff", ".aif", ".aifc" -> "audio/aiff"
             ".lrc" -> "application/octet-stream"
             else -> "application/octet-stream"
         }
@@ -791,6 +825,8 @@ class MainActivity: FlutterFragmentActivity() {
             "audio/mpeg" -> ".mp3"
             "audio/ogg" -> ".opus"
             "audio/flac" -> ".flac"
+            "audio/wav", "audio/x-wav", "audio/wave", "audio/vnd.wave" -> ".wav"
+            "audio/aiff", "audio/x-aiff" -> ".aiff"
             else -> ""
         }
     }
@@ -1113,6 +1149,16 @@ class MainActivity: FlutterFragmentActivity() {
         ".flac", ".wav", ".ape", ".mp3", ".ogg", ".wv", ".m4a", ".mp4", ".aac"
     )
 
+    // Audio file extensions that the local library scanner accepts. Must stay in
+    // sync with supportedAudioFormats in go_backend/library_scan.go so that every
+    // format the Go engine can read (FLAC, M4A/MP4/AAC, MP3, Opus/OGG, APE/WV/MPC,
+    // WAV, AIFF) is also enumerated here during the SAF folder walk. (.cue is
+    // handled separately.)
+    private val libraryScanAudioExtensions = setOf(
+        ".flac", ".m4a", ".mp4", ".aac", ".mp3", ".opus", ".ogg",
+        ".ape", ".wv", ".mpc", ".wav", ".aiff", ".aif"
+    )
+
     private fun getSafChildFileLookup(
         dir: DocumentFile,
         cache: MutableMap<String, Map<String, DocumentFile>>,
@@ -1182,7 +1228,7 @@ class MainActivity: FlutterFragmentActivity() {
             it.currentFile = "Scanning folders..."
         }
 
-        val supportedAudioExt = setOf(".flac", ".m4a", ".mp4", ".aac", ".mp3", ".opus", ".ogg")
+        val supportedAudioExt = libraryScanAudioExtensions
         val audioFiles = mutableListOf<Pair<DocumentFile, String>>()
         val cueFiles = mutableListOf<Pair<DocumentFile, DocumentFile>>()
         val visitedDirUris = mutableSetOf<String>()
@@ -1482,7 +1528,7 @@ class MainActivity: FlutterFragmentActivity() {
             it.currentFile = "Scanning folders..."
         }
 
-        val supportedAudioExt = setOf(".flac", ".m4a", ".mp4", ".aac", ".mp3", ".opus", ".ogg")
+        val supportedAudioExt = libraryScanAudioExtensions
         val audioFiles = mutableListOf<Triple<DocumentFile, String, Long>>()
         val cueFilesToScan = mutableListOf<Triple<DocumentFile, DocumentFile, Long>>()
         val unchangedCueFiles = mutableListOf<Pair<DocumentFile, DocumentFile>>()
@@ -2035,14 +2081,22 @@ class MainActivity: FlutterFragmentActivity() {
         }
         val host = (uri.host ?: "").lowercase(Locale.US)
         val path = (uri.path ?: "").lowercase(Locale.US)
+        val isSessionGrant = host == "session-grant"
         val isCallback =
-            host == "callback" ||
+            isSessionGrant ||
+                host == "callback" ||
                 host == "spotify-callback" ||
                 path.contains("callback")
         if (!isCallback) {
             return
         }
-        val code = uri.getQueryParameter("code")?.trim().orEmpty()
+        val code = (
+            if (isSessionGrant) {
+                uri.getQueryParameter("grant") ?: uri.getQueryParameter("code")
+            } else {
+                uri.getQueryParameter("code")
+            }
+        )?.trim().orEmpty()
         if (code.isEmpty()) {
             return
         }
@@ -2054,15 +2108,43 @@ class MainActivity: FlutterFragmentActivity() {
         intent.data = null
         scope.launch(Dispatchers.IO) {
             try {
-                Gobackend.setExtensionAuthCodeByID(extId, code)
-                val json = Gobackend.invokeExtensionActionJSON(extId, "completeSpotifyLogin")
-                android.util.Log.i("SpotiFLAC", "Extension OAuth complete for $extId: $json")
+                val json = if (isSessionGrant) {
+                    Gobackend.setExtensionSessionGrantByID(extId, code)
+                    Gobackend.invokeExtensionActionJSON(extId, "completeGrant")
+                } else {
+                    Gobackend.setExtensionAuthCodeByID(extId, code)
+                    Gobackend.invokeExtensionActionJSON(extId, "completeSpotifyLogin")
+                }
+                android.util.Log.i("SpotiFLAC", "Extension callback complete for $extId: $json")
+                if (isSessionGrant) {
+                    withContext(Dispatchers.Main) {
+                        notifySessionGrantCompleted(extId, true)
+                    }
+                }
             } catch (e: Exception) {
-                android.util.Log.w("SpotiFLAC", "Extension OAuth failed: ${e.message}")
+                android.util.Log.w("SpotiFLAC", "Extension callback failed: ${e.message}")
+                if (isSessionGrant) {
+                    withContext(Dispatchers.Main) {
+                        notifySessionGrantCompleted(extId, false)
+                    }
+                }
             }
         }
     }
 
+    private fun notifySessionGrantCompleted(extensionId: String, success: Boolean) {
+        val payload = mapOf(
+            "extension_id" to extensionId,
+            "success" to success,
+        )
+        val channel = backendChannel
+        if (channel == null) {
+            pendingSessionGrantEvents.add(payload)
+            return
+        }
+        channel.invokeMethod("extensionSessionGrantCompleted", payload)
+    }
+
     override fun onDestroy() {
         try {
             Gobackend.cleanupExtensions()
@@ -2126,7 +2208,17 @@ class MainActivity: FlutterFragmentActivity() {
             },
         )
 
-        MethodChannel(messenger, CHANNEL).setMethodCallHandler { call, result ->
+        val channel = MethodChannel(messenger, CHANNEL)
+        backendChannel = channel
+        if (pendingSessionGrantEvents.isNotEmpty()) {
+            val events = pendingSessionGrantEvents.toList()
+            pendingSessionGrantEvents.clear()
+            for (event in events) {
+                channel.invokeMethod("extensionSessionGrantCompleted", event)
+            }
+        }
+
+        channel.setMethodCallHandler { call, result ->
             scope.launch {
                 try {
                     when (call.method) {
@@ -2211,6 +2303,13 @@ class MainActivity: FlutterFragmentActivity() {
                             }
                             result.success(null)
                         }
+                        "setAllowPrivateNetwork" -> {
+                            val allowed = call.argument<Boolean>("allowed") ?: false
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setAllowPrivateNetwork(allowed)
+                            }
+                            result.success(null)
+                        }
                         "checkDuplicate" -> {
                             val outputDir = call.argument<String>("output_dir") ?: ""
                             val isrc = call.argument<String>("isrc") ?: ""
@@ -2629,6 +2728,46 @@ class MainActivity: FlutterFragmentActivity() {
                             }
                             result.success(response)
                         }
+                        "writeM4AFreeformTags" -> {
+                            val filePath = call.argument<String>("file_path") ?: ""
+                            val metadataJson = call.argument<String>("metadata_json") ?: "{}"
+                            val response = withContext(Dispatchers.IO) {
+                                try {
+                                    Gobackend.writeM4AFreeformTags(filePath, metadataJson)
+                                } catch (e: Exception) {
+                                    android.util.Log.e("SpotiFLAC", "writeM4AFreeformTags failed: ${e.message}", e)
+                                    """{"error":"${e.message?.replace("\"", "'")}"}"""
+                                }
+                            }
+                            result.success(response)
+                        }
+                        "ensureAC4Config" -> {
+                            val filePath = call.argument<String>("file_path") ?: ""
+                            val sourcePath = call.argument<String>("source_path") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                try {
+                                    Gobackend.ensureAC4Config(filePath, sourcePath)
+                                } catch (e: Exception) {
+                                    android.util.Log.e("SpotiFLAC", "ensureAC4Config failed: ${e.message}", e)
+                                    """{"error":"${e.message?.replace("\"", "'")}"}"""
+                                }
+                            }
+                            result.success(response)
+                        }
+                        "writeAC4Metadata" -> {
+                            val filePath = call.argument<String>("file_path") ?: ""
+                            val metadataJson = call.argument<String>("metadata_json") ?: "{}"
+                            val coverPath = call.argument<String>("cover_path") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                try {
+                                    Gobackend.writeAC4Metadata(filePath, metadataJson, coverPath)
+                                } catch (e: Exception) {
+                                    android.util.Log.e("SpotiFLAC", "writeAC4Metadata failed: ${e.message}", e)
+                                    """{"error":"${e.message?.replace("\"", "'")}"}"""
+                                }
+                            }
+                            result.success(response)
+                        }
                         "writeTempToSaf" -> {
                             val tempPath = call.argument<String>("temp_path") ?: ""
                             val safUri = call.argument<String>("saf_uri") ?: ""

android/app/src/main/kotlin/com/zarz/spotiflac/NativeDownloadFinalizer.kt

@@ -334,7 +334,6 @@ object NativeDownloadFinalizer {
     }
 
     private fun currentStatus(@Suppress("UNUSED_PARAMETER") status: String) {
-        // Kept as a narrow hook for future richer progress snapshots.
     }
 
     private fun cleanupFailedFinalizationOutput(
@@ -422,16 +421,19 @@ object NativeDownloadFinalizer {
         try {
             for (candidate in decryptionKeyCandidates(key)) {
                 checkCancelled(shouldCancel)
-                val attempts = mutableListOf<Pair<String, Boolean>>()
-                attempts.add(outputPath to (preferredExt == ".flac"))
+                val attempts = mutableListOf<Triple<String, Boolean, Boolean>>()
+                attempts.add(Triple(outputPath, preferredExt == ".flac", false))
                 if (preferredExt == ".flac") {
-                    attempts.add(buildOutputPath(localInput, ".m4a") to false)
+                    attempts.add(Triple(buildOutputPath(localInput, ".m4a"), false, false))
                 }
                 if (preferredExt == ".flac" || preferredExt == ".m4a") {
-                    attempts.add(buildOutputPath(localInput, ".mp4") to false)
+                    attempts.add(Triple(buildOutputPath(localInput, ".mp4"), false, false))
                 }
+                // MOV muxer fallback for codecs the MP4 muxer rejects (e.g. AC-4):
+                // keeps the .mp4 filename but stores the codec params.
+                attempts.add(Triple(buildOutputPath(localInput, ".mp4"), false, true))
 
-                for ((candidateOutput, mapAudioOnly) in attempts) {
+                for ((candidateOutput, mapAudioOnly, forceMov) in attempts) {
                     try {
                         val audioMap = if (mapAudioOnly) "-map 0:a " else ""
                         // Force the flac muxer when the target extension is
@@ -439,7 +441,11 @@ object NativeDownloadFinalizer {
                         // stream layout, producing FLAC-in-MP4 under a .flac
                         // filename which downstream native FLAC tag writers
                         // cannot read.
-                        val muxerOverride = if (candidateOutput.lowercase(Locale.ROOT).endsWith(".flac")) "-f flac " else ""
+                        val muxerOverride = when {
+                            forceMov -> "-f mov "
+                            candidateOutput.lowercase(Locale.ROOT).endsWith(".flac") -> "-f flac "
+                            else -> ""
+                        }
                         val command = "-v error -decryption_key ${q(candidate)} -f $inputFormat -i ${q(localInput)} ${audioMap}-c copy ${muxerOverride}${q(candidateOutput)} -y"
                         val result = runFFmpeg(command, shouldCancel)
                         lastOutput = result.second
@@ -1159,18 +1165,28 @@ object NativeDownloadFinalizer {
         val mp3Flags = if (format == "mp3") "-id3v2_version 3 " else ""
         var adoptedTemp = false
         var originalDeleted = false
-        try {
-            val command = if (isM4a && coverFile != null) {
+
+        fun buildEmbedCommand(forceMov: Boolean): String {
+            return if (isM4a && coverFile != null) {
                 "-v error -hide_banner -i ${q(path)} -i ${q(coverFile.absolutePath)} " +
                     "-map 0:a -c:a copy -map_metadata 0 -map 1:v -c:v copy " +
                     "-disposition:v:0 attached_pic " +
                     "-metadata:s:v ${q("title=Album cover")} " +
                     "-metadata:s:v ${q("comment=Cover (front)")} " +
-                    "$metadataArgs -f mp4 ${q(temp.absolutePath)} -y"
+                    "$metadataArgs -f ${if (forceMov) "mov" else "mp4"} ${q(temp.absolutePath)} -y"
             } else {
-                "-v error -hide_banner -i ${q(path)} -map 0 -c copy -map_metadata 0 $metadataArgs $mp3Flags${q(temp.absolutePath)} -y"
+                val movFlag = if (forceMov) "-f mov " else ""
+                "-v error -hide_banner -i ${q(path)} -map 0 -c copy -map_metadata 0 $metadataArgs $mp3Flags$movFlag${q(temp.absolutePath)} -y"
+            }
+        }
+
+        try {
+            var result = runFFmpeg(buildEmbedCommand(false))
+            // MOV muxer fallback for codecs the MP4 muxer rejects (e.g. AC-4).
+            if (!result.first && (isM4a || ext.equals(".mp4", ignoreCase = true))) {
+                temp.delete()
+                result = runFFmpeg(buildEmbedCommand(true))
             }
-            val result = runFFmpeg(command)
             if (result.first && temp.exists()) {
                 if (inputFile.delete()) {
                     originalDeleted = true

android/app/src/main/res/xml/automotive_app_desc.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<automotiveApp>
+    <uses name="media" />
+</automotiveApp>

android/build.gradle.kts

@@ -11,8 +11,8 @@ subprojects {
             project.extensions.configure<com.android.build.gradle.BaseExtension>("android") {
                 compileOptions {
                     isCoreLibraryDesugaringEnabled = true
-                    sourceCompatibility = JavaVersion.VERSION_17
-                    targetCompatibility = JavaVersion.VERSION_17
+                    sourceCompatibility = JavaVersion.VERSION_25
+                    targetCompatibility = JavaVersion.VERSION_25
                 }
                 
                 // Enable multidex for all subprojects
@@ -27,7 +27,7 @@ subprojects {
         
         tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile>().configureEach {
             compilerOptions {
-                jvmTarget.set(org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_17)
+                jvmTarget.set(org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_25)
             }
         }
     }

apps.json

@@ -7,12 +7,12 @@
       "name": "SpotiFLAC Mobile",
       "bundleIdentifier": "com.zarzet.spotiflac",
       "developerName": "zarzet",
-      "version": "4.5.5",
-      "versionDate": "2026-05-14",
-      "downloadURL": "https://github.com/zarzet/SpotiFLAC-Mobile/releases/download/v4.5.5/SpotiFLAC-v4.5.5-ios-unsigned.ipa",
+      "version": "4.7.1",
+      "versionDate": "2026-07-01",
+      "downloadURL": "https://github.com/zarzet/SpotiFLAC-Mobile/releases/download/v4.7.1/SpotiFLAC-v4.7.1-ios-unsigned.ipa",
       "localizedDescription": "SpotiFLAC Mobile is written in Flutter. Download tracks in true FLAC from Tidal, Qobuz, & Amazon Music.",
       "iconURL": "https://raw.githubusercontent.com/zarzet/SpotiFLAC-Mobile/main/assets/images/logo.png",
-      "size": 34915749
+      "size": 37455821
     }
   ]
 }

crowdin.yml

@@ -3,9 +3,11 @@ files:
     translation: /lib/l10n/arb/app_%locale%.arb
     languages_mapping:
       locale:
-        # Short codes for single-variant languages
+        # Keys MUST be the project's Crowdin language ids; values are the
+        # %locale% suffix used in app_%locale%.arb (underscores so Flutter
+        # gen-l10n parses them — hyphenated filenames break gen-l10n).
+        ar: ar
         de: de
-        es: es
         es-ES: es_ES
         fr: fr
         hi: hi
@@ -13,12 +15,9 @@ files:
         ja: ja
         ko: ko
         nl: nl
-        pt: pt
         pt-PT: pt_PT
         ru: ru
         tr: tr
         uk: uk
-        zh: zh
-        # Full codes for Chinese variants
         zh-CN: zh_CN
         zh-TW: zh_TW

go_backend/ac4_config.go

@@ -0,0 +1,322 @@
+package gobackend
+
+import (
+	"encoding/binary"
+	"fmt"
+	"os"
+)
+
+// mp4Box is a minimal ISO-BMFF / QuickTime box view over an in-memory buffer.
+type mp4Box struct {
+	offset int64
+	size   int64
+	hdr    int64
+	typ    string
+}
+
+func (b mp4Box) body() int64 { return b.offset + b.hdr }
+func (b mp4Box) end() int64  { return b.offset + b.size }
+
+func readMP4Box(data []byte, pos int64) (mp4Box, bool) {
+	n := int64(len(data))
+	if pos < 0 || pos+8 > n {
+		return mp4Box{}, false
+	}
+	size := int64(binary.BigEndian.Uint32(data[pos : pos+4]))
+	typ := string(data[pos+4 : pos+8])
+	hdr := int64(8)
+	if size == 1 {
+		if pos+16 > n {
+			return mp4Box{}, false
+		}
+		size = int64(binary.BigEndian.Uint64(data[pos+8 : pos+16]))
+		hdr = 16
+	} else if size == 0 {
+		size = n - pos
+	}
+	if size < hdr || pos+size > n {
+		return mp4Box{}, false
+	}
+	return mp4Box{offset: pos, size: size, hdr: hdr, typ: typ}, true
+}
+
+func findChildMP4(data []byte, start, end int64, typ string) (mp4Box, bool) {
+	pos := start
+	for pos+8 <= end {
+		b, ok := readMP4Box(data, pos)
+		if !ok {
+			return mp4Box{}, false
+		}
+		if b.typ == typ {
+			return b, true
+		}
+		pos = b.end()
+	}
+	return mp4Box{}, false
+}
+
+func eachChildMP4(data []byte, start, end int64, typ string, fn func(mp4Box) bool) {
+	pos := start
+	for pos+8 <= end {
+		b, ok := readMP4Box(data, pos)
+		if !ok {
+			return
+		}
+		if b.typ == typ && !fn(b) {
+			return
+		}
+		pos = b.end()
+	}
+}
+
+// findBoxBySignature scans [start,end) for a box of the given type, matching the
+// 4-byte type tag and validating the preceding size field. Used to locate dac4
+// which may be nested inside an encrypted (enca) sample entry.
+func findBoxBySignature(data []byte, start, end int64, typ string) (mp4Box, bool) {
+	if len(typ) != 4 {
+		return mp4Box{}, false
+	}
+	for i := start; i+8 <= end; i++ {
+		if data[i+4] == typ[0] && data[i+5] == typ[1] && data[i+6] == typ[2] && data[i+7] == typ[3] {
+			if b, ok := readMP4Box(data, i); ok && b.typ == typ {
+				return b, true
+			}
+		}
+	}
+	return mp4Box{}, false
+}
+
+// audioSampleEntryHeaderLen returns the byte length of the fixed audio sample
+// entry header (from the box body start) before child boxes begin. ok is false
+// for malformed/truncated entries whose declared header is not fully present.
+func audioSampleEntryHeaderLen(data []byte, entry mp4Box) (hdrLen int64, ok bool) {
+	// 6 bytes reserved + 2 bytes data_reference_index, then the audio fields.
+	base := entry.body()
+	if base+10 > entry.end() {
+		return 0, false
+	}
+	version := binary.BigEndian.Uint16(data[base+8 : base+10])
+	hdrLen = 8 + 20
+	switch version {
+	case 1:
+		hdrLen += 16
+	case 2:
+		hdrLen += 36
+	}
+	if base+hdrLen > entry.end() {
+		return 0, false
+	}
+	return hdrLen, true
+}
+
+type ac4Location struct {
+	chain []mp4Box // moov, trak, mdia, minf, stbl, stsd (ancestors to grow)
+	entry mp4Box   // the ac-4 sample entry
+}
+
+func locateAC4Entry(data []byte) (ac4Location, bool) {
+	moov, ok := findChildMP4(data, 0, int64(len(data)), "moov")
+	if !ok {
+		return ac4Location{}, false
+	}
+	var found ac4Location
+	var ok2 bool
+	eachChildMP4(data, moov.body(), moov.end(), "trak", func(trak mp4Box) bool {
+		mdia, ok := findChildMP4(data, trak.body(), trak.end(), "mdia")
+		if !ok {
+			return true
+		}
+		minf, ok := findChildMP4(data, mdia.body(), mdia.end(), "minf")
+		if !ok {
+			return true
+		}
+		stbl, ok := findChildMP4(data, minf.body(), minf.end(), "stbl")
+		if !ok {
+			return true
+		}
+		stsd, ok := findChildMP4(data, stbl.body(), stbl.end(), "stsd")
+		if !ok {
+			return true
+		}
+		entry, ok := findChildMP4(data, stsd.body()+8, stsd.end(), "ac-4")
+		if !ok {
+			return true
+		}
+		found = ac4Location{chain: []mp4Box{moov, trak, mdia, minf, stbl, stsd}, entry: entry}
+		ok2 = true
+		return false
+	})
+	return found, ok2
+}
+
+func growBoxSize(data []byte, b mp4Box, delta int64) {
+	if b.hdr == 16 {
+		binary.BigEndian.PutUint64(data[b.offset+8:b.offset+16], uint64(b.size+delta))
+	} else {
+		binary.BigEndian.PutUint32(data[b.offset:b.offset+4], uint32(b.size+delta))
+	}
+}
+
+// shiftChunkOffsets adds delta to every stco/co64 entry that references a file
+// offset at or beyond insertPos, keeping sample pointers valid after bytes are
+// inserted into moov.
+func shiftChunkOffsets(data []byte, moov mp4Box, insertPos, delta int64) {
+	eachChildMP4(data, moov.body(), moov.end(), "trak", func(trak mp4Box) bool {
+		mdia, ok := findChildMP4(data, trak.body(), trak.end(), "mdia")
+		if !ok {
+			return true
+		}
+		minf, ok := findChildMP4(data, mdia.body(), mdia.end(), "minf")
+		if !ok {
+			return true
+		}
+		stbl, ok := findChildMP4(data, minf.body(), minf.end(), "stbl")
+		if !ok {
+			return true
+		}
+		if stco, ok := findChildMP4(data, stbl.body(), stbl.end(), "stco"); ok {
+			base := stco.body() + 4
+			if base+4 <= stco.end() {
+				count := int64(binary.BigEndian.Uint32(data[base : base+4]))
+				p := base + 4
+				for i := int64(0); i < count && p+4 <= stco.end(); i++ {
+					v := int64(binary.BigEndian.Uint32(data[p : p+4]))
+					if v >= insertPos {
+						binary.BigEndian.PutUint32(data[p:p+4], uint32(v+delta))
+					}
+					p += 4
+				}
+			}
+		}
+		if co64, ok := findChildMP4(data, stbl.body(), stbl.end(), "co64"); ok {
+			base := co64.body() + 4
+			if base+4 <= co64.end() {
+				count := int64(binary.BigEndian.Uint32(data[base : base+4]))
+				p := base + 4
+				for i := int64(0); i < count && p+8 <= co64.end(); i++ {
+					v := int64(binary.BigEndian.Uint64(data[p : p+8]))
+					if v >= insertPos {
+						binary.BigEndian.PutUint64(data[p:p+8], uint64(v+delta))
+					}
+					p += 8
+				}
+			}
+		}
+		return true
+	})
+}
+
+// normalizeQuickTimeAudioToMP4 rewrites a QuickTime-flavored file (FFmpeg mov
+// muxer output: ftyp brand "qt  " and a version-1 sound sample entry) into a
+// standard ISO MP4: an isom/mp42 brand and a plain version-0 AudioSampleEntry.
+// Windows Media Foundation (and other strict parsers) reject the QuickTime
+// flavor for AC-4 even when dac4 is present.
+func normalizeQuickTimeAudioToMP4(data []byte) []byte {
+	if ftyp, ok := findChildMP4(data, 0, int64(len(data)), "ftyp"); ok {
+		if ftyp.body()+4 <= int64(len(data)) {
+			copy(data[ftyp.body():ftyp.body()+4], []byte("mp42"))
+		}
+		for p := ftyp.body() + 8; p+4 <= ftyp.end(); p += 4 {
+			if string(data[p:p+4]) == "qt  " {
+				copy(data[p:p+4], []byte("isom"))
+			}
+		}
+	}
+
+	loc, ok := locateAC4Entry(data)
+	if !ok {
+		return data
+	}
+	entry := loc.entry
+	verPos := entry.body() + 8
+	if verPos+2 > entry.end() {
+		return data
+	}
+	if binary.BigEndian.Uint16(data[verPos:verPos+2]) != 1 {
+		return data // already v0 (or v2, left untouched)
+	}
+
+	// The v1 QuickTime sound extension is the 16 bytes following the 20-byte v0
+	// audio fields (samplesPerPacket, bytesPerPacket, bytesPerFrame, bytesPerSample).
+	extStart := entry.body() + 8 + 20
+	extEnd := extStart + 16
+	if extEnd > entry.end() {
+		return data
+	}
+	delta := int64(-16)
+
+	binary.BigEndian.PutUint16(data[verPos:verPos+2], 0)
+	shiftChunkOffsets(data, loc.chain[0], extStart, delta)
+	for _, b := range loc.chain {
+		growBoxSize(data, b, delta)
+	}
+	growBoxSize(data, entry, delta)
+
+	out := make([]byte, 0, len(data)-16)
+	out = append(out, data[:extStart]...)
+	out = append(out, data[extEnd:]...)
+	return out
+}
+
+// EnsureAC4ConfigBox makes a decrypted AC-4 MP4 standards-compliant and
+// playable: it normalizes FFmpeg's QuickTime-flavored mov output to an ISO MP4
+// and injects the AC-4 configuration box (dac4) into the ac-4 sample entry. The
+// dac4 box is copied verbatim from sourcePath (the original MP4, whose plaintext
+// moov still carries it). No-op when the file has no AC-4 track.
+func EnsureAC4ConfigBox(decryptedPath, sourcePath string) error {
+	dst, err := os.ReadFile(decryptedPath)
+	if err != nil {
+		return err
+	}
+
+	if _, ok := locateAC4Entry(dst); !ok {
+		return nil // not an AC-4 file; nothing to do
+	}
+
+	dst = normalizeQuickTimeAudioToMP4(dst)
+
+	loc, ok := locateAC4Entry(dst)
+	if !ok {
+		return nil
+	}
+
+	hdrLen, ok := audioSampleEntryHeaderLen(dst, loc.entry)
+	if !ok {
+		return fmt.Errorf("malformed ac-4 sample entry")
+	}
+	childStart := loc.entry.body() + hdrLen
+	if _, has := findChildMP4(dst, childStart, loc.entry.end(), "dac4"); has {
+		// Already has dac4; still persist any normalization changes.
+		return os.WriteFile(decryptedPath, dst, 0o644)
+	}
+
+	src, err := os.ReadFile(sourcePath)
+	if err != nil {
+		return err
+	}
+	srcMoov, ok := findChildMP4(src, 0, int64(len(src)), "moov")
+	if !ok {
+		return fmt.Errorf("source has no moov")
+	}
+	dac4Box, ok := findBoxBySignature(src, srcMoov.body(), srcMoov.end(), "dac4")
+	if !ok {
+		return fmt.Errorf("dac4 not found in source")
+	}
+	dac4 := append([]byte{}, src[dac4Box.offset:dac4Box.end()]...)
+
+	insertPos := childStart
+	delta := int64(len(dac4))
+
+	shiftChunkOffsets(dst, loc.chain[0], insertPos, delta)
+	for _, b := range loc.chain {
+		growBoxSize(dst, b, delta)
+	}
+	growBoxSize(dst, loc.entry, delta)
+
+	out := make([]byte, 0, len(dst)+len(dac4))
+	out = append(out, dst[:insertPos]...)
+	out = append(out, dac4...)
+	out = append(out, dst[insertPos:]...)
+
+	return os.WriteFile(decryptedPath, out, 0o644)
+}

go_backend/ac4_config_test.go

@@ -0,0 +1,76 @@
+package gobackend
+
+import (
+	"bytes"
+	"encoding/binary"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func mp4TestBox(typ string, body []byte) []byte {
+	out := make([]byte, 8+len(body))
+	binary.BigEndian.PutUint32(out[:4], uint32(len(out)))
+	copy(out[4:8], typ)
+	copy(out[8:], body)
+	return out
+}
+
+func mp4TestAC4Tree(entryBody []byte) []byte {
+	entry := mp4TestBox("ac-4", entryBody)
+	stsdBody := append([]byte{
+		0, 0, 0, 0, // version/flags
+		0, 0, 0, 1, // entry_count
+	}, entry...)
+	stsd := mp4TestBox("stsd", stsdBody)
+	stbl := mp4TestBox("stbl", stsd)
+	minf := mp4TestBox("minf", stbl)
+	mdia := mp4TestBox("mdia", minf)
+	trak := mp4TestBox("trak", mdia)
+	moov := mp4TestBox("moov", trak)
+	return moov
+}
+
+func shortAC4SampleEntryBody(version uint16) []byte {
+	body := make([]byte, 10)
+	binary.BigEndian.PutUint16(body[8:10], version)
+	return body
+}
+
+func TestNormalizeQuickTimeAudioToMP4IgnoresTruncatedAC4Entry(t *testing.T) {
+	input := mp4TestAC4Tree(shortAC4SampleEntryBody(1))
+
+	defer func() {
+		if r := recover(); r != nil {
+			t.Fatalf("normalizeQuickTimeAudioToMP4 panicked: %v", r)
+		}
+	}()
+
+	got := normalizeQuickTimeAudioToMP4(append([]byte{}, input...))
+	if !bytes.Equal(got, input) {
+		t.Fatal("truncated QuickTime AC-4 entry should be left unchanged")
+	}
+}
+
+func TestEnsureAC4ConfigBoxRejectsTruncatedAC4Entry(t *testing.T) {
+	dir := t.TempDir()
+	decryptedPath := filepath.Join(dir, "decrypted.mp4")
+	sourcePath := filepath.Join(dir, "source.mp4")
+
+	if err := os.WriteFile(decryptedPath, mp4TestAC4Tree(shortAC4SampleEntryBody(2)), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(sourcePath, mp4TestBox("moov", mp4TestBox("dac4", []byte{1, 2, 3, 4})), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	defer func() {
+		if r := recover(); r != nil {
+			t.Fatalf("EnsureAC4ConfigBox panicked: %v", r)
+		}
+	}()
+
+	if err := EnsureAC4ConfigBox(decryptedPath, sourcePath); err == nil {
+		t.Fatal("expected malformed AC-4 sample entry error")
+	}
+}

go_backend/ac4_metadata.go

@@ -0,0 +1,182 @@
+package gobackend
+
+import (
+	"encoding/binary"
+	"encoding/json"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// ac4Metadata mirrors the tag fields the app embeds for other formats. Numeric
+// fields are strings because they arrive as a JSON-encoded map of strings.
+type ac4Metadata struct {
+	Title       string `json:"title"`
+	Artist      string `json:"artist"`
+	Album       string `json:"album"`
+	AlbumArtist string `json:"albumArtist"`
+	Date        string `json:"date"`
+	Genre       string `json:"genre"`
+	Composer    string `json:"composer"`
+	TrackNumber string `json:"trackNumber"`
+	TotalTracks string `json:"totalTracks"`
+	DiscNumber  string `json:"discNumber"`
+	TotalDiscs  string `json:"totalDiscs"`
+	ISRC        string `json:"isrc"`
+	Label       string `json:"label"`
+	Copyright   string `json:"copyright"`
+	Lyrics      string `json:"lyrics"`
+}
+
+func atoiSafe(s string) int {
+	n, err := strconv.Atoi(strings.TrimSpace(s))
+	if err != nil {
+		return 0
+	}
+	return n
+}
+
+func itunesTextTag(atomType, value string) []byte {
+	data := make([]byte, 8+len(value))
+	binary.BigEndian.PutUint32(data[0:4], 1) // well-known type 1 = UTF-8
+	copy(data[8:], []byte(value))
+	return buildM4AAtom(atomType, buildM4AAtom("data", data))
+}
+
+func itunesNumberPairTag(atomType string, number, total int) []byte {
+	payload := make([]byte, 8)
+	binary.BigEndian.PutUint16(payload[2:4], uint16(number))
+	binary.BigEndian.PutUint16(payload[4:6], uint16(total))
+	data := make([]byte, 8+len(payload))
+	binary.BigEndian.PutUint32(data[0:4], 0) // type 0 = implicit/binary
+	copy(data[8:], payload)
+	return buildM4AAtom(atomType, buildM4AAtom("data", data))
+}
+
+func itunesCoverTag(image []byte) []byte {
+	typeCode := uint32(13) // JPEG
+	if len(image) >= 8 &&
+		image[0] == 0x89 && image[1] == 0x50 && image[2] == 0x4E && image[3] == 0x47 {
+		typeCode = 14 // PNG
+	}
+	data := make([]byte, 8+len(image))
+	binary.BigEndian.PutUint32(data[0:4], typeCode)
+	copy(data[8:], image)
+	return buildM4AAtom("covr", buildM4AAtom("data", data))
+}
+
+func itunesMetadataHandler() []byte {
+	payload := make([]byte, 0, 25)
+	payload = append(payload, 0, 0, 0, 0)            // version + flags
+	payload = append(payload, 0, 0, 0, 0)            // pre_defined
+	payload = append(payload, []byte("mdir")...)     // handler type
+	payload = append(payload, []byte("appl")...)     // reserved[0]
+	payload = append(payload, 0, 0, 0, 0, 0, 0, 0, 0) // reserved[1..2]
+	payload = append(payload, 0)                     // empty name
+	return buildM4AAtom("hdlr", payload)
+}
+
+// buildITunesUdta assembles a fresh udta>meta>(hdlr+ilst) box from metadata.
+func buildITunesUdta(md ac4Metadata, cover []byte) []byte {
+	ilst := make([]byte, 0, 256)
+	add := func(atomType, value string) {
+		if strings.TrimSpace(value) != "" {
+			ilst = append(ilst, itunesTextTag(atomType, value)...)
+		}
+	}
+	add("\xa9nam", md.Title)
+	add("\xa9ART", md.Artist)
+	add("\xa9alb", md.Album)
+	add("aART", md.AlbumArtist)
+	add("\xa9day", md.Date)
+	add("\xa9gen", md.Genre)
+	add("\xa9wrt", md.Composer)
+	if tn := atoiSafe(md.TrackNumber); tn > 0 {
+		ilst = append(ilst, itunesNumberPairTag("trkn", tn, atoiSafe(md.TotalTracks))...)
+	}
+	if dn := atoiSafe(md.DiscNumber); dn > 0 {
+		ilst = append(ilst, itunesNumberPairTag("disk", dn, atoiSafe(md.TotalDiscs))...)
+	}
+	if strings.TrimSpace(md.ISRC) != "" {
+		ilst = append(ilst, buildM4AFreeformAtom("ISRC", strings.TrimSpace(md.ISRC))...)
+	}
+	if strings.TrimSpace(md.Label) != "" {
+		ilst = append(ilst, buildM4AFreeformAtom("LABEL", strings.TrimSpace(md.Label))...)
+	}
+	if strings.TrimSpace(md.Copyright) != "" {
+		add("cprt", md.Copyright)
+	}
+	if strings.TrimSpace(md.Lyrics) != "" {
+		add("\xa9lyr", md.Lyrics)
+	}
+	if len(cover) > 0 {
+		ilst = append(ilst, itunesCoverTag(cover)...)
+	}
+
+	ilstBox := buildM4AAtom("ilst", ilst)
+	metaPayload := append([]byte{0, 0, 0, 0}, itunesMetadataHandler()...)
+	metaPayload = append(metaPayload, ilstBox...)
+	meta := buildM4AAtom("meta", metaPayload)
+	return buildM4AAtom("udta", meta)
+}
+
+// writeMP4iTunesMetadata replaces (or inserts) a udta>meta>ilst metadata box in
+// the moov of an MP4 buffer and returns the rewritten bytes.
+func writeMP4iTunesMetadata(data []byte, md ac4Metadata, cover []byte) []byte {
+	moov, ok := findChildMP4(data, 0, int64(len(data)), "moov")
+	if !ok {
+		return data
+	}
+	newUdta := buildITunesUdta(md, cover)
+
+	if udta, ok := findChildMP4(data, moov.body(), moov.end(), "udta"); ok {
+		delta := int64(len(newUdta)) - udta.size
+		shiftChunkOffsets(data, moov, udta.offset, delta)
+		growBoxSize(data, moov, delta)
+		out := make([]byte, 0, len(data)+len(newUdta))
+		out = append(out, data[:udta.offset]...)
+		out = append(out, newUdta...)
+		out = append(out, data[udta.end():]...)
+		return out
+	}
+
+	delta := int64(len(newUdta))
+	insertPos := moov.end()
+	shiftChunkOffsets(data, moov, insertPos, delta)
+	growBoxSize(data, moov, delta)
+	out := make([]byte, 0, len(data)+len(newUdta))
+	out = append(out, data[:insertPos]...)
+	out = append(out, newUdta...)
+	out = append(out, data[insertPos:]...)
+	return out
+}
+
+// WriteAC4MetadataIfApplicable writes iTunes metadata into an AC-4 MP4. Returns
+// true when the file was an AC-4 track and metadata was written; false when the
+// file is not AC-4 (the caller should fall back to its normal metadata path).
+func WriteAC4MetadataIfApplicable(decryptedPath, metadataJSON, coverPath string) (bool, error) {
+	data, err := os.ReadFile(decryptedPath)
+	if err != nil {
+		return false, err
+	}
+	if _, ok := locateAC4Entry(data); !ok {
+		return false, nil
+	}
+
+	var md ac4Metadata
+	if strings.TrimSpace(metadataJSON) != "" {
+		_ = json.Unmarshal([]byte(metadataJSON), &md)
+	}
+	var cover []byte
+	if strings.TrimSpace(coverPath) != "" {
+		if b, err := os.ReadFile(coverPath); err == nil {
+			cover = b
+		}
+	}
+
+	out := writeMP4iTunesMetadata(data, md, cover)
+	if err := os.WriteFile(decryptedPath, out, 0o644); err != nil {
+		return false, err
+	}
+	return true, nil
+}

go_backend/ape_tags.go

@@ -314,7 +314,6 @@ func marshalAPETag(tag *APETag) ([]byte, error) {
 	footerFlags := uint32(1 << 31)
 	footer := buildAPEHeaderFooter(version, tagSize, itemCount, footerFlags)
 
-	// Final layout: header + items + footer
 	result := make([]byte, 0, len(header)+len(itemsData)+len(footer))
 	result = append(result, header...)
 	result = append(result, itemsData...)

go_backend/audio_metadata.go

@@ -1624,6 +1624,9 @@ func extractAnyCoverArtWithHint(filePath, displayNameHint string) ([]byte, strin
 		}
 		return data, mimeType, nil
 
+	case ".wav", ".aiff", ".aif", ".aifc":
+		return extractWAVAIFFCover(filePath)
+
 	default:
 		return nil, "", fmt.Errorf("unsupported format: %s", ext)
 	}

go_backend/cue_parser.go

@@ -264,7 +264,7 @@ func ResolveCueAudioPath(cuePath string, cueFileName string) string {
 	}
 
 	baseName := strings.TrimSuffix(cueFileName, filepath.Ext(cueFileName))
-	commonExts := []string{".flac", ".wav", ".ape", ".mp3", ".ogg", ".wv", ".m4a"}
+	commonExts := []string{".flac", ".wav", ".aiff", ".aif", ".ape", ".mp3", ".ogg", ".wv", ".m4a"}
 	for _, ext := range commonExts {
 		candidate = filepath.Join(cueDir, baseName+ext)
 		if _, err := os.Stat(candidate); err == nil {

go_backend/deezer.go

@@ -3,6 +3,7 @@ package gobackend
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -783,7 +784,6 @@ func (c *DeezerClient) GetArtist(ctx context.Context, artistID string) (*ArtistR
 // not include this field. Albums whose track count is already known (non-zero)
 // are skipped.
 func (c *DeezerClient) fetchAlbumTrackCounts(ctx context.Context, albums []ArtistAlbumMetadata) {
-	// Find albums that need track counts
 	type indexedID struct {
 		idx     int
 		albumID string
@@ -1267,16 +1267,7 @@ func (c *DeezerClient) getJSON(ctx context.Context, endpoint string, dst interfa
 		}
 
 		lastErr = err
-		errStr := err.Error()
-
-		isRetryable := strings.Contains(errStr, "timeout") ||
-			strings.Contains(errStr, "connection reset") ||
-			strings.Contains(errStr, "connection refused") ||
-			strings.Contains(errStr, "EOF") ||
-			strings.Contains(errStr, "status 5") ||
-			strings.Contains(errStr, "status 429")
-
-		if !isRetryable {
+		if !isDeezerRetryableError(err) {
 			return err
 		}
 
@@ -1286,6 +1277,26 @@ func (c *DeezerClient) getJSON(ctx context.Context, endpoint string, dst interfa
 	return fmt.Errorf("all %d attempts failed: %w", deezerMaxRetries+1, lastErr)
 }
 
+type deezerAPIError struct {
+	StatusCode int
+	Body       string
+}
+
+func (e *deezerAPIError) Error() string {
+	return fmt.Sprintf("deezer API returned status %d: %s", e.StatusCode, e.Body)
+}
+
+func isDeezerRetryableError(err error) bool {
+	if isConnectivityFailure(err) || errors.Is(err, io.ErrUnexpectedEOF) {
+		return true
+	}
+	var apiErr *deezerAPIError
+	if errors.As(err, &apiErr) {
+		return apiErr.StatusCode == http.StatusTooManyRequests || apiErr.StatusCode >= http.StatusInternalServerError
+	}
+	return false
+}
+
 func (c *DeezerClient) doGetJSON(ctx context.Context, endpoint string, dst interface{}) error {
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
 	if err != nil {
@@ -1306,7 +1317,7 @@ func (c *DeezerClient) doGetJSON(ctx context.Context, endpoint string, dst inter
 	}
 
 	if resp.StatusCode != http.StatusOK {
-		return fmt.Errorf("deezer API returned status %d: %s", resp.StatusCode, string(body))
+		return &deezerAPIError{StatusCode: resp.StatusCode, Body: string(body)}
 	}
 
 	return json.Unmarshal(body, dst)

go_backend/exports.go

@@ -283,6 +283,7 @@ type DownloadRequest struct {
 	PostProcessingEnabled       bool   `json:"post_processing_enabled,omitempty"`
 	TidalHighFormat             string `json:"tidal_high_format,omitempty"`
 	TrackNumber                 int    `json:"track_number"`
+	PlaylistPosition            int    `json:"playlist_position,omitempty"`
 	DiscNumber                  int    `json:"disc_number"`
 	TotalTracks                 int    `json:"total_tracks"`
 	TotalDiscs                  int    `json:"total_discs,omitempty"`
@@ -310,6 +311,7 @@ type DownloadResponse struct {
 	FilePath                    string                  `json:"file_path,omitempty"`
 	Error                       string                  `json:"error,omitempty"`
 	ErrorType                   string                  `json:"error_type,omitempty"`
+	RetryAfterSeconds           int                     `json:"retry_after_seconds,omitempty"`
 	AlreadyExists               bool                    `json:"already_exists,omitempty"`
 	ActualBitDepth              int                     `json:"actual_bit_depth,omitempty"`
 	ActualSampleRate            int                     `json:"actual_sample_rate,omitempty"`
@@ -1160,6 +1162,8 @@ func ReadFileMetadata(filePath string) (string, error) {
 	isApe := strings.HasSuffix(lower, ".ape")
 	isWv := strings.HasSuffix(lower, ".wv")
 	isMpc := strings.HasSuffix(lower, ".mpc")
+	isWav := strings.HasSuffix(lower, ".wav")
+	isAiff := strings.HasSuffix(lower, ".aiff") || strings.HasSuffix(lower, ".aif") || strings.HasSuffix(lower, ".aifc")
 
 	result := map[string]interface{}{
 		"title":        "",
@@ -1376,7 +1380,6 @@ func ReadFileMetadata(filePath string) (string, error) {
 	} else if isApe || isWv || isMpc {
 		result["format"] = strings.TrimPrefix(filepath.Ext(filePath), ".")
 		result["audio_codec"] = result["format"]
-		// APE, WavPack, Musepack: read APEv2 tags
 		apeTag, apeErr := ReadAPETags(filePath)
 		if apeErr == nil && apeTag != nil {
 			meta := APETagToAudioMetadata(apeTag)
@@ -1406,6 +1409,51 @@ func ReadFileMetadata(filePath string) (string, error) {
 				result["replaygain_album_peak"] = meta.ReplayGainAlbumPeak
 			}
 		}
+	} else if isWav || isAiff {
+		var meta *AudioMetadata
+		var quality *WAVQuality
+		var qualityErr error
+		if isAiff {
+			result["format"] = "aiff"
+			result["audio_codec"] = "pcm"
+			meta, _ = ReadAIFFTags(filePath)
+			quality, qualityErr = GetAIFFQuality(filePath)
+		} else {
+			result["format"] = "wav"
+			result["audio_codec"] = "pcm"
+			meta, _ = ReadWAVTags(filePath)
+			quality, qualityErr = GetWAVQuality(filePath)
+		}
+		if meta != nil {
+			result["title"] = meta.Title
+			result["artist"] = meta.Artist
+			result["album"] = meta.Album
+			result["album_artist"] = meta.AlbumArtist
+			result["date"] = meta.Date
+			if meta.Date == "" {
+				result["date"] = meta.Year
+			}
+			result["track_number"] = meta.TrackNumber
+			result["total_tracks"] = meta.TotalTracks
+			result["disc_number"] = meta.DiscNumber
+			result["total_discs"] = meta.TotalDiscs
+			result["isrc"] = meta.ISRC
+			result["lyrics"] = meta.Lyrics
+			result["genre"] = meta.Genre
+			result["label"] = meta.Label
+			result["copyright"] = meta.Copyright
+			result["composer"] = meta.Composer
+			result["comment"] = meta.Comment
+			result["replaygain_track_gain"] = meta.ReplayGainTrackGain
+			result["replaygain_track_peak"] = meta.ReplayGainTrackPeak
+			result["replaygain_album_gain"] = meta.ReplayGainAlbumGain
+			result["replaygain_album_peak"] = meta.ReplayGainAlbumPeak
+		}
+		if qualityErr == nil && quality != nil {
+			result["bit_depth"] = quality.BitDepth
+			result["sample_rate"] = quality.SampleRate
+			result["duration"] = quality.Duration
+		}
 	} else {
 		return "", fmt.Errorf("unsupported file format: %s", filePath)
 	}
@@ -1463,6 +1511,48 @@ func ScanCueSheetForLibraryWithCoverCacheKey(cuePath, audioDir, virtualPathPrefi
 	return string(jsonBytes), nil
 }
 
+// WriteM4AFreeformTags writes ISRC and label into an M4A/MP4 file as iTunes
+// freeform atoms. FFmpeg's MP4 muxer ignores these keys, so they must be
+// written natively after the FFmpeg metadata pass for the values to persist.
+// Only keys present in the JSON are touched; an empty value clears the tag.
+func WriteM4AFreeformTags(filePath, metadataJSON string) (string, error) {
+	var fields map[string]string
+	if err := json.Unmarshal([]byte(metadataJSON), &fields); err != nil {
+		return "", fmt.Errorf("invalid metadata JSON: %w", err)
+	}
+
+	if err := EditM4AFreeformText(filePath, fields); err != nil {
+		return "", fmt.Errorf("failed to write M4A freeform tags: %w", err)
+	}
+
+	resp := map[string]any{"success": true, "method": "native_m4a_freeform"}
+	jsonBytes, _ := json.Marshal(resp)
+	return string(jsonBytes), nil
+}
+
+// EnsureAC4Config normalizes a decrypted AC-4 file to a standards-compliant ISO
+// MP4 and injects the dac4 configuration box copied from sourcePath. No-op when
+// the file is not AC-4.
+func EnsureAC4Config(filePath, sourcePath string) (string, error) {
+	if err := EnsureAC4ConfigBox(filePath, sourcePath); err != nil {
+		return "", fmt.Errorf("failed to finalize AC-4 container: %w", err)
+	}
+	return `{"success":true}`, nil
+}
+
+// WriteAC4Metadata writes iTunes-style metadata into an AC-4 MP4. The JSON
+// "handled" field reports whether the file was AC-4 (true) so the caller can
+// skip the FFmpeg metadata pass that would re-wrap it as QuickTime.
+func WriteAC4Metadata(filePath, metadataJSON, coverPath string) (string, error) {
+	handled, err := WriteAC4MetadataIfApplicable(filePath, metadataJSON, coverPath)
+	if err != nil {
+		return "", fmt.Errorf("failed to write AC-4 metadata: %w", err)
+	}
+	resp := map[string]any{"success": true, "handled": handled}
+	jsonBytes, _ := json.Marshal(resp)
+	return string(jsonBytes), nil
+}
+
 // EditFileMetadata writes audio file tags: FLAC via native Go library, MP3/Opus returns map for Dart/FFmpeg.
 func EditFileMetadata(filePath, metadataJSON string) (string, error) {
 	var fields map[string]string
@@ -1474,6 +1564,8 @@ func EditFileMetadata(filePath, metadataJSON string) (string, error) {
 	isFlac := strings.HasSuffix(lower, ".flac")
 	isApeFile := strings.HasSuffix(lower, ".ape") || strings.HasSuffix(lower, ".wv") || strings.HasSuffix(lower, ".mpc")
 	isM4AFile := strings.HasSuffix(lower, ".m4a") || strings.HasSuffix(lower, ".mp4") || strings.HasSuffix(lower, ".m4b")
+	isWavFile := strings.HasSuffix(lower, ".wav")
+	isAiffFile := strings.HasSuffix(lower, ".aiff") || strings.HasSuffix(lower, ".aif") || strings.HasSuffix(lower, ".aifc")
 	coverPath := strings.TrimSpace(fields["cover_path"])
 
 	if hasOnlyM4AReplayGainFields(fields) && (isM4AFile || isMP4ContainerFile(filePath)) {
@@ -1502,7 +1594,24 @@ func EditFileMetadata(filePath, metadataJSON string) (string, error) {
 		return string(jsonBytes), nil
 	}
 
-	// APE/WV/MPC: write APEv2 tags natively
+	// WAV / AIFF: write tags into an embedded ID3v2.4 chunk natively.
+	if isWavFile {
+		if err := WriteWAVTags(filePath, fields); err != nil {
+			return "", fmt.Errorf("failed to write WAV metadata: %w", err)
+		}
+		resp := map[string]any{"success": true, "method": "native_wav"}
+		jsonBytes, _ := json.Marshal(resp)
+		return string(jsonBytes), nil
+	}
+	if isAiffFile {
+		if err := WriteAIFFTags(filePath, fields); err != nil {
+			return "", fmt.Errorf("failed to write AIFF metadata: %w", err)
+		}
+		resp := map[string]any{"success": true, "method": "native_aiff"}
+		jsonBytes, _ := json.Marshal(resp)
+		return string(jsonBytes), nil
+	}
+
 	if isApeFile {
 		trackNum := 0
 		totalTracks := 0
@@ -1751,9 +1860,13 @@ func GetLyricsLRCWithSource(spotifyID, trackName, artistName string, filePath st
 	if filePath != "" {
 		lyrics, err := ExtractLyrics(filePath)
 		if err == nil && lyrics != "" {
+			source := extractLyricsSourceFromLRC(lyrics)
+			if source == "" {
+				source = "Embedded"
+			}
 			result := map[string]interface{}{
 				"lyrics":       lyrics,
-				"source":       "Embedded",
+				"source":       source,
 				"sync_type":    "EMBEDDED",
 				"instrumental": false,
 			}
@@ -1964,6 +2077,7 @@ func normalizeExtensionTrackMetadataMap(
 		"duration_ms":   track.DurationMS,
 		"images":        coverURL,
 		"cover_url":     coverURL,
+		"preview_url":   track.PreviewURL,
 		"release_date":  track.ReleaseDate,
 		"track_number":  trackNum,
 		"total_tracks":  track.TotalTracks,
@@ -1992,9 +2106,12 @@ func normalizeExtensionAlbumInfoMap(album *ExtAlbumMetadata) map[string]interfac
 		"artist_id":    album.ArtistID,
 		"images":       album.CoverURL,
 		"cover_url":    album.CoverURL,
+		"header_image": album.HeaderImage,
+		"header_video": album.HeaderVideo,
 		"release_date": album.ReleaseDate,
 		"total_tracks": album.TotalTracks,
 		"album_type":   album.AlbumType,
+		"audio_traits": album.AudioTraits,
 		"provider_id":  album.ProviderID,
 	}
 }
@@ -2079,11 +2196,13 @@ func getExtensionProviderMetadataResponse(
 
 		return map[string]interface{}{
 			"playlist_info": map[string]interface{}{
-				"id":          playlist.ID,
-				"name":        playlist.Name,
-				"images":      playlist.CoverURL,
-				"cover_url":   playlist.CoverURL,
-				"provider_id": playlist.ProviderID,
+				"id":           playlist.ID,
+				"name":         playlist.Name,
+				"images":       playlist.CoverURL,
+				"cover_url":    playlist.CoverURL,
+				"header_image": playlist.HeaderImage,
+				"header_video": playlist.HeaderVideo,
+				"provider_id":  playlist.ProviderID,
 				"owner": map[string]interface{}{
 					"name":   playlist.Artists,
 					"images": playlist.CoverURL,
@@ -2112,6 +2231,7 @@ func getExtensionProviderMetadataResponse(
 				"images":       firstNonEmptyTrimmed(artist.HeaderImage, artist.ImageURL),
 				"cover_url":    artist.ImageURL,
 				"header_image": artist.HeaderImage,
+				"header_video": artist.HeaderVideo,
 				"provider_id":  artist.ProviderID,
 			},
 			"albums": albums,
@@ -2161,6 +2281,16 @@ func GetProviderMetadataJSON(providerID, resourceType, resourceID string) (strin
 
 	switch strings.ToLower(trimmedProviderID) {
 	case "deezer":
+		if response, ok, err := getEnabledExtensionProviderMetadataResponse(trimmedProviderID, resourceType, resourceID); ok || err != nil {
+			if err != nil {
+				return "", err
+			}
+			jsonBytes, err := json.Marshal(response)
+			if err != nil {
+				return "", err
+			}
+			return string(jsonBytes), nil
+		}
 		return GetDeezerMetadata(resourceType, resourceID)
 	default:
 		response, err := getExtensionProviderMetadataResponse(trimmedProviderID, resourceType, resourceID)
@@ -2176,6 +2306,19 @@ func GetProviderMetadataJSON(providerID, resourceType, resourceID string) (strin
 	}
 }
 
+func getEnabledExtensionProviderMetadataResponse(providerID, resourceType, resourceID string) (map[string]interface{}, bool, error) {
+	manager := getExtensionManager()
+	ext, err := manager.GetExtension(providerID)
+	if err != nil || ext == nil || !ext.Enabled || !ext.Manifest.IsMetadataProvider() {
+		return nil, false, nil
+	}
+	response, err := getExtensionProviderMetadataResponse(providerID, resourceType, resourceID)
+	if err != nil {
+		return nil, true, err
+	}
+	return response, true, nil
+}
+
 func GetDeezerExtendedMetadata(trackID string) (string, error) {
 	if trackID == "" {
 		return "", fmt.Errorf("empty track ID")
@@ -2399,8 +2542,19 @@ func classifyDownloadErrorType(msg string) string {
 		return "isp_blocked"
 	} else if strings.Contains(lowerMsg, "cancel") {
 		return "cancelled"
+	} else if strings.Contains(lowerMsg, "verify_required") ||
+		strings.Contains(lowerMsg, "verification_required") ||
+		strings.Contains(lowerMsg, "verification required") ||
+		strings.Contains(lowerMsg, "needs verification") ||
+		strings.Contains(lowerMsg, "session is not authenticated") ||
+		strings.Contains(lowerMsg, "signed session is not authenticated") ||
+		strings.Contains(lowerMsg, "unauthorized") ||
+		strings.Contains(lowerMsg, "precondition required") ||
+		messageHasHTTPStatusCode(lowerMsg, "401") ||
+		messageHasHTTPStatusCode(lowerMsg, "428") {
+		return "verification_required"
 	} else if strings.Contains(lowerMsg, "rate limit") ||
-		strings.Contains(lowerMsg, "429") ||
+		messageHasHTTPStatusCode(lowerMsg, "429") ||
 		strings.Contains(lowerMsg, "too many requests") {
 		return "rate_limit"
 	} else if strings.Contains(lowerMsg, "permission") ||
@@ -2425,6 +2579,15 @@ func classifyDownloadErrorType(msg string) string {
 	return "unknown"
 }
 
+func messageHasHTTPStatusCode(lowerMsg, code string) bool {
+	return strings.Contains(lowerMsg, "http "+code) ||
+		strings.Contains(lowerMsg, "http status "+code) ||
+		strings.Contains(lowerMsg, "status "+code) ||
+		strings.Contains(lowerMsg, code+" for ") ||
+		strings.Contains(lowerMsg, code+":") ||
+		strings.Contains(lowerMsg, code+";")
+}
+
 func DownloadCoverToFile(coverURL string, outputPath string, maxQuality bool) error {
 	if coverURL == "" {
 		return fmt.Errorf("no cover URL provided")
@@ -2577,8 +2740,6 @@ func ReEnrichFile(requestJSON string) (string, error) {
 
 	GoLog("[ReEnrich] Starting re-enrichment for: %s\n", req.FilePath)
 
-	// When search_online is true, search for metadata from internet using the
-	// configured metadata-provider priority.
 	if req.SearchOnline {
 		found := false
 
@@ -2747,7 +2908,6 @@ func ReEnrichFile(requestJSON string) (string, error) {
 	}
 
 	if isFlac {
-		// Native Go FLAC metadata embedding.
 		// Only populate Metadata fields for selected update groups; empty/zero
 		// values cause EmbedMetadata's setComment() to skip those tags,
 		// preserving whatever is already in the file.
@@ -3127,7 +3287,7 @@ func InvokeExtensionActionJSON(extensionID, actionName string) (string, error) {
 }
 
 func GetExtensionPendingAuthJSON(extensionID string) (string, error) {
-	req := GetPendingAuthRequest(extensionID)
+	req := ensureExtensionPendingAuthRequest(extensionID)
 	if req == nil {
 		return "", nil
 	}
@@ -3146,10 +3306,48 @@ func GetExtensionPendingAuthJSON(extensionID string) (string, error) {
 	return string(jsonBytes), nil
 }
 
+func ensureExtensionPendingAuthRequest(extensionID string) *PendingAuthRequest {
+	extensionID = strings.TrimSpace(extensionID)
+	if extensionID == "" {
+		return nil
+	}
+
+	if req := GetPendingAuthRequest(extensionID); req != nil {
+		return req
+	}
+
+	manager := getExtensionManager()
+	ext, err := manager.GetExtension(extensionID)
+	if err != nil || ext == nil || !ext.Enabled || ext.Manifest == nil || ext.Manifest.SignedSession == nil {
+		return nil
+	}
+
+	if err := ext.ensureRuntimeReady(); err != nil || ext.runtime == nil {
+		return nil
+	}
+
+	config := signedSessionConfigWithDefaults(ext.Manifest.SignedSession)
+	if config.Namespace == "" || config.BaseURL == "" {
+		return nil
+	}
+	if record, err := ext.runtime.loadSignedSession(config); err == nil {
+		record.SessionID = ""
+		record.SessionSecret = ""
+		record.ExpiresAt = ""
+		_ = ext.runtime.saveSignedSession(config, record)
+	}
+	ext.runtime.startSignedSessionVerification(config, "pending-auth-request")
+	return GetPendingAuthRequest(extensionID)
+}
+
 func SetExtensionAuthCodeByID(extensionID, authCode string) {
 	SetExtensionAuthCode(extensionID, authCode)
 }
 
+func SetExtensionSessionGrantByID(extensionID, grant string) {
+	setPendingSignedSessionGrant(extensionID, grant)
+}
+
 func SetExtensionTokensByID(extensionID, accessToken, refreshToken string, expiresIn int) {
 	var expiresAt time.Time
 	if expiresIn > 0 {
@@ -3316,6 +3514,7 @@ func CustomSearchWithExtensionJSONWithRequestID(extensionID, query string, optio
 			"album_artist":  track.AlbumArtist,
 			"duration_ms":   track.DurationMS,
 			"images":        track.ResolvedCoverURL(),
+			"preview_url":   track.PreviewURL,
 			"release_date":  track.ReleaseDate,
 			"track_number":  track.TrackNumber,
 			"total_tracks":  track.TotalTracks,
@@ -3381,6 +3580,8 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 		"extension_id": extensionID,
 		"name":         result.Name,
 		"cover_url":    result.CoverURL,
+		"header_image": result.HeaderImage,
+		"header_video": result.HeaderVideo,
 	}
 
 	if result.Track != nil {
@@ -3392,6 +3593,7 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 			"album_artist": result.Track.AlbumArtist,
 			"duration_ms":  result.Track.DurationMS,
 			"images":       result.Track.ResolvedCoverURL(),
+			"preview_url":  result.Track.PreviewURL,
 			"release_date": result.Track.ReleaseDate,
 			"track_number": result.Track.TrackNumber,
 			"total_tracks": result.Track.TotalTracks,
@@ -3414,6 +3616,7 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 				"album_artist": track.AlbumArtist,
 				"duration_ms":  track.DurationMS,
 				"images":       track.ResolvedCoverURL(),
+				"preview_url":  track.PreviewURL,
 				"release_date": track.ReleaseDate,
 				"track_number": track.TrackNumber,
 				"total_tracks": track.TotalTracks,
@@ -3435,6 +3638,9 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 			"name":         result.Album.Name,
 			"artists":      result.Album.Artists,
 			"cover_url":    result.Album.CoverURL,
+			"header_image": result.Album.HeaderImage,
+			"header_video": result.Album.HeaderVideo,
+			"audio_traits": result.Album.AudioTraits,
 			"release_date": result.Album.ReleaseDate,
 			"total_tracks": result.Album.TotalTracks,
 			"album_type":   result.Album.AlbumType,
@@ -3448,6 +3654,7 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 			"name":         result.Artist.Name,
 			"image_url":    result.Artist.ImageURL,
 			"header_image": result.Artist.HeaderImage,
+			"header_video": result.Artist.HeaderVideo,
 			"listeners":    result.Artist.Listeners,
 			"provider_id":  result.Artist.ProviderID,
 		}
@@ -3507,6 +3714,7 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 					"album_artist": track.AlbumArtist,
 					"duration_ms":  track.DurationMS,
 					"images":       track.ResolvedCoverURL(),
+					"preview_url":  track.PreviewURL,
 					"release_date": track.ReleaseDate,
 					"track_number": track.TrackNumber,
 					"total_tracks": track.TotalTracks,
@@ -3742,13 +3950,29 @@ func GetStoreCategoriesJSON() (string, error) {
 	return string(jsonBytes), nil
 }
 
-func buildStoreExtensionDestPath(destDir, extensionID string) (string, error) {
+func storeExtensionPackageSuffix(downloadURL string) string {
+	rawPath := downloadURL
+	if parsed, err := url.Parse(downloadURL); err == nil {
+		rawPath = parsed.Path
+	}
+
+	lowerPath := strings.ToLower(rawPath)
+	if strings.HasSuffix(lowerPath, ".sflx") {
+		return ".sflx"
+	}
+	if strings.HasSuffix(lowerPath, ".spotiflac-ext") {
+		return ".spotiflac-ext"
+	}
+	return ".spotiflac-ext"
+}
+
+func buildStoreExtensionDestPath(destDir, extensionID, downloadURL string) (string, error) {
 	if strings.TrimSpace(extensionID) == "" {
 		return "", fmt.Errorf("invalid extension id")
 	}
 
 	safeExtensionID := sanitizeFilename(extensionID)
-	return filepath.Join(destDir, safeExtensionID+".spotiflac-ext"), nil
+	return filepath.Join(destDir, safeExtensionID+storeExtensionPackageSuffix(downloadURL)), nil
 }
 
 func DownloadStoreExtensionJSON(extensionID, destDir string) (string, error) {
@@ -3757,7 +3981,12 @@ func DownloadStoreExtensionJSON(extensionID, destDir string) (string, error) {
 		return "", fmt.Errorf("extension store not initialized")
 	}
 
-	destPath, err := buildStoreExtensionDestPath(destDir, extensionID)
+	ext, err := store.findExtension(extensionID)
+	if err != nil {
+		return "", err
+	}
+
+	destPath, err := buildStoreExtensionDestPath(destDir, extensionID, ext.getDownloadURL())
 	if err != nil {
 		return "", err
 	}
@@ -3822,9 +4051,12 @@ func callExtensionFunctionJSONWithRequestID(extensionID, functionName string, ti
 			if (typeof extension !== 'undefined' && typeof extension.%s === 'function') {
 				return extension.%s();
 			}
+			if (typeof %s === 'function') {
+				return %s();
+			}
 			return null;
 		})()
-	`, functionName, functionName)
+	`, functionName, functionName, functionName, functionName)
 
 	jsStartedAt := time.Now()
 	result, err := RunWithTimeoutContextAndRecover(requestCtx, vm, script, timeout)

go_backend/exports_supplement_test.go

@@ -31,6 +31,44 @@ func TestDownloadErrorClassificationPrioritizesRateLimit(t *testing.T) {
 	}
 }
 
+func TestDownloadErrorClassificationDetectsVerificationRequired(t *testing.T) {
+	cases := []string{
+		"HTTP 401 for /tickets",
+		"HTTP status 428: precondition required",
+		"Verification required",
+	}
+	for _, tc := range cases {
+		if got := classifyDownloadErrorType(tc); got != "verification_required" {
+			t.Fatalf("classifyDownloadErrorType(%q) = %q, want verification_required", tc, got)
+		}
+	}
+}
+
+func TestGetProviderMetadataPrefersEnabledDeezerExtension(t *testing.T) {
+	dir := t.TempDir()
+	if err := InitExtensionSystem(filepath.Join(dir, "extensions"), filepath.Join(dir, "data")); err != nil {
+		t.Fatalf("InitExtensionSystem: %v", err)
+	}
+	CleanupExtensions()
+	defer CleanupExtensions()
+
+	ext := newTestLoadedExtension(t, ExtensionTypeMetadataProvider)
+	ext.ID = "deezer"
+	ext.Manifest.Name = "deezer"
+	manager := getExtensionManager()
+	manager.mu.Lock()
+	manager.extensions = map[string]*loadedExtension{ext.ID: ext}
+	manager.mu.Unlock()
+
+	jsonText, err := GetProviderMetadataJSON("deezer", "album", "201")
+	if err != nil {
+		t.Fatalf("GetProviderMetadataJSON deezer album: %v", err)
+	}
+	if !strings.Contains(jsonText, "album-track") {
+		t.Fatalf("expected enabled deezer extension metadata, got %s", jsonText)
+	}
+}
+
 func TestExportsJSONWrappersAndExtensionManagerSurface(t *testing.T) {
 	dir := t.TempDir()
 	dataDir := filepath.Join(dir, "data")
@@ -390,10 +428,25 @@ func TestExportsJSONWrappersAndExtensionManagerSurface(t *testing.T) {
 	if catsJSON, err := GetStoreCategoriesJSON(); err != nil || !strings.Contains(catsJSON, "metadata") {
 		t.Fatalf("GetStoreCategoriesJSON = %q/%v", catsJSON, err)
 	}
-	if dest, err := buildStoreExtensionDestPath(dir, "coverage/ext"); err != nil || !strings.HasSuffix(dest, ".spotiflac-ext") {
+	if dest, err := buildStoreExtensionDestPath(
+		dir,
+		"coverage/ext",
+		"https://registry.example.com/coverage.spotiflac-ext",
+	); err != nil || !strings.HasSuffix(dest, ".spotiflac-ext") {
 		t.Fatalf("buildStoreExtensionDestPath = %q/%v", dest, err)
 	}
-	if _, err := buildStoreExtensionDestPath(dir, " "); err == nil {
+	if dest, err := buildStoreExtensionDestPath(
+		dir,
+		"coverage/ext",
+		"https://registry.example.com/coverage.sflx",
+	); err != nil || !strings.HasSuffix(dest, ".sflx") {
+		t.Fatalf("buildStoreExtensionDestPath sflx = %q/%v", dest, err)
+	}
+	if _, err := buildStoreExtensionDestPath(
+		dir,
+		" ",
+		"https://registry.example.com/coverage.sflx",
+	); err == nil {
 		t.Fatal("expected invalid extension id")
 	}
 	if err := ClearStoreCacheJSON(); err != nil {

go_backend/extension_health.go

@@ -15,7 +15,9 @@ import (
 const (
 	extensionHealthDefaultTimeout = 4 * time.Second
 	extensionHealthMaxBodyBytes   = 64 * 1024
-	extensionHealthDefaultCache   = 60 * time.Second
+	extensionHealthDefaultCache   = 10 * time.Minute
+	extensionHealthMinCache       = 60 * time.Second
+	extensionHealthUnknownCache   = 2 * time.Minute
 )
 
 type ExtensionHealthResult struct {
@@ -58,6 +60,7 @@ func CheckExtensionHealthJSON(extensionID string) (string, error) {
 	}
 
 	result := CheckExtensionHealth(ext)
+	cacheExtensionHealthResult(ext, result)
 	bytes, err := json.Marshal(result)
 	if err != nil {
 		return "", err
@@ -85,16 +88,31 @@ func CheckExtensionHealthCached(ext *loadedExtension) ExtensionHealthResult {
 	extensionHealthCacheMu.Unlock()
 
 	result := CheckExtensionHealth(ext)
+	cacheExtensionHealthResult(ext, result)
+	return result
+}
+
+func cacheExtensionHealthResult(ext *loadedExtension, result ExtensionHealthResult) {
+	if ext == nil || ext.Manifest == nil || len(ext.Manifest.ServiceHealth) == 0 {
+		return
+	}
+
+	cacheKey := strings.TrimSpace(ext.ID)
+	if cacheKey == "" {
+		return
+	}
+
 	ttl := extensionHealthCacheTTL(ext.Manifest.ServiceHealth)
+	if result.Status == "unknown" && ttl > extensionHealthUnknownCache {
+		ttl = extensionHealthUnknownCache
+	}
 
 	extensionHealthCacheMu.Lock()
 	extensionHealthCache[cacheKey] = cachedExtensionHealthResult{
 		result:    result,
-		expiresAt: now.Add(ttl),
+		expiresAt: time.Now().Add(ttl),
 	}
 	extensionHealthCacheMu.Unlock()
-
-	return result
 }
 
 func CheckExtensionHealth(ext *loadedExtension) ExtensionHealthResult {
@@ -149,6 +167,9 @@ func extensionHealthCacheTTL(checks []ExtensionHealthCheck) time.Duration {
 			continue
 		}
 		checkTTL := time.Duration(check.CacheTTLSeconds) * time.Second
+		if checkTTL < extensionHealthMinCache {
+			checkTTL = extensionHealthMinCache
+		}
 		if checkTTL < ttl {
 			ttl = checkTTL
 		}
@@ -226,7 +247,11 @@ func runExtensionHealthCheck(manifest *ExtensionManifest, check ExtensionHealthC
 	resp, err := NewMetadataHTTPClient(timeout).Do(req)
 	result.LatencyMs = time.Since(start).Milliseconds()
 	if err != nil {
-		result.Status = "offline"
+		if isTransientExtensionHealthError(err) {
+			result.Status = "unknown"
+		} else {
+			result.Status = "offline"
+		}
 		result.Error = err.Error()
 		return result
 	}
@@ -262,6 +287,10 @@ func runExtensionHealthCheck(manifest *ExtensionManifest, check ExtensionHealthC
 	return result
 }
 
+func isTransientExtensionHealthError(err error) bool {
+	return isTransientNetworkError(err) || isConnectivityFailure(err)
+}
+
 func classifyExtensionHealthBody(body []byte, serviceKey string) (string, string) {
 	if len(strings.TrimSpace(string(body))) == 0 {
 		return "online", ""
@@ -287,6 +316,9 @@ func classifyExtensionHealthBody(body []byte, serviceKey string) (string, string
 	case "degraded", "partial", "warning", "warn":
 		return "degraded", rawStatus
 	case "down", "offline", "error", "failed", "fail", "unhealthy":
+		if isTransientHealthStatusMessage(string(body)) {
+			return "unknown", rawStatus
+		}
 		return "offline", rawStatus
 	default:
 		return "online", rawStatus
@@ -327,42 +359,53 @@ func classifyExtensionHealthService(payload map[string]interface{}, serviceKey s
 
 	rawStatus, hasStatus := service["status"]
 	okValue, hasOK := service["ok"].(bool)
+	joinedMessage := strings.Join(messageParts, ": ")
+	transient := isTransientHealthStatusMessage(detail) ||
+		isTransientHealthStatusMessage(errText) ||
+		isTransientHealthStatusMessage(label)
+
 	if statusCode, ok := healthNumber(rawStatus); ok {
 		if statusCode >= 200 && statusCode < 300 {
-			return "online", strings.Join(messageParts, ": "), true
+			return "online", joinedMessage, true
 		}
 		if statusCode == http.StatusUnauthorized || statusCode == http.StatusForbidden {
-			return "degraded", strings.Join(messageParts, ": "), true
+			return "degraded", joinedMessage, true
 		}
 		if statusCode == http.StatusInternalServerError && hasOK && okValue {
-			return "online", strings.Join(messageParts, ": "), true
+			return "online", joinedMessage, true
 		}
-		return "offline", strings.Join(messageParts, ": "), true
+		if transient || isTransientHealthStatusCode(statusCode) {
+			return "unknown", joinedMessage, true
+		}
+		return "offline", joinedMessage, true
 	}
 
 	if isExtensionHealthAuthRequired(detail) {
-		return "degraded", strings.Join(messageParts, ": "), true
+		return "degraded", joinedMessage, true
+	}
+	if transient {
+		return "unknown", joinedMessage, true
 	}
 	if hasOK {
 		if okValue {
-			return "online", strings.Join(messageParts, ": "), true
+			return "online", joinedMessage, true
 		}
-		return "offline", strings.Join(messageParts, ": "), true
+		return "offline", joinedMessage, true
 	}
 	if !hasStatus {
-		return "unknown", strings.Join(messageParts, ": "), true
+		return "unknown", joinedMessage, true
 	}
 
 	statusString := strings.ToLower(strings.TrimSpace(fmt.Sprintf("%v", rawStatus)))
 	switch statusString {
 	case "ok", "up", "online", "healthy", "operational":
-		return "online", strings.Join(messageParts, ": "), true
+		return "online", joinedMessage, true
 	case "degraded", "partial", "warning", "warn":
-		return "degraded", strings.Join(messageParts, ": "), true
+		return "degraded", joinedMessage, true
 	case "down", "offline", "error", "failed", "fail", "unhealthy":
-		return "offline", strings.Join(messageParts, ": "), true
+		return "offline", joinedMessage, true
 	default:
-		return "unknown", strings.Join(messageParts, ": "), true
+		return "unknown", joinedMessage, true
 	}
 }
 
@@ -375,6 +418,32 @@ func isExtensionHealthAuthRequired(detail string) bool {
 	}
 }
 
+func isTransientHealthStatusMessage(text string) bool {
+	t := strings.ToLower(strings.TrimSpace(text))
+	if t == "" {
+		return false
+	}
+	return strings.Contains(t, "context deadline exceeded") ||
+		strings.Contains(t, "deadline exceeded") ||
+		strings.Contains(t, "timeout") ||
+		strings.Contains(t, "timed out") ||
+		strings.Contains(t, "temporarily unavailable") ||
+		strings.Contains(t, "try again")
+}
+
+func isTransientHealthStatusCode(code int) bool {
+	switch code {
+	case http.StatusRequestTimeout,
+		http.StatusTooManyRequests,
+		http.StatusBadGateway,
+		http.StatusServiceUnavailable,
+		http.StatusGatewayTimeout:
+		return true
+	default:
+		return false
+	}
+}
+
 func healthNumber(value interface{}) (int, bool) {
 	switch v := value.(type) {
 	case float64:

go_backend/extension_health_misc_supplement_test.go

@@ -1,8 +1,10 @@
 package gobackend
 
 import (
+	"context"
 	"encoding/json"
 	"io"
+	"net"
 	"net/http"
 	"strings"
 	"testing"
@@ -27,6 +29,12 @@ func TestExtensionHealthClassificationAndValidation(t *testing.T) {
 	if !isExtensionHealthAuthRequired(" unauthorized ") {
 		t.Fatal("expected auth required")
 	}
+	if !isTransientExtensionHealthError(context.DeadlineExceeded) || !isTransientExtensionHealthError(&net.DNSError{IsTimeout: true}) {
+		t.Fatal("expected timeout health errors to be transient")
+	}
+	if !isTransientExtensionHealthError(&net.DNSError{IsNotFound: true}) {
+		t.Fatal("expected health transport lookup errors to be indeterminate")
+	}
 
 	if result := CheckExtensionHealth(nil); result.Status != "offline" {
 		t.Fatalf("nil health = %#v", result)

go_backend/extension_manager.go

@@ -44,18 +44,24 @@ func compareVersions(v1, v2 string) int {
 	return 0
 }
 
+func isExtensionPackagePath(filePath string) bool {
+	lowerPath := strings.ToLower(filePath)
+	return strings.HasSuffix(lowerPath, ".spotiflac-ext") || strings.HasSuffix(lowerPath, ".sflx")
+}
+
 type loadedExtension struct {
-	ID          string             `json:"id"`
-	Manifest    *ExtensionManifest `json:"manifest"`
-	VM          *goja.Runtime      `json:"-"`
-	VMMu        sync.Mutex         `json:"-"`
-	runtime     *extensionRuntime
-	initialized bool
-	Enabled     bool   `json:"enabled"`
-	Error       string `json:"error,omitempty"`
-	DataDir     string `json:"data_dir"`
-	SourceDir   string `json:"source_dir"`
-	IconPath    string `json:"icon_path"`
+	ID           string             `json:"id"`
+	Manifest     *ExtensionManifest `json:"manifest"`
+	VM           *goja.Runtime      `json:"-"`
+	VMMu         sync.Mutex         `json:"-"`
+	runtime      *extensionRuntime
+	indexProgram *goja.Program
+	initialized  bool
+	Enabled      bool   `json:"enabled"`
+	Error        string `json:"error,omitempty"`
+	DataDir      string `json:"data_dir"`
+	SourceDir    string `json:"source_dir"`
+	IconPath     string `json:"icon_path"`
 }
 
 func getExtensionInitSettings(extensionID string) map[string]interface{} {
@@ -118,7 +124,11 @@ func (ext *loadedExtension) lockReadyVM() (*goja.Runtime, error) {
 }
 
 type extensionManager struct {
-	mu            sync.RWMutex
+	mu sync.RWMutex
+	// mutationMu serializes install/upgrade/remove (heavy FS + goja VM
+	// teardown/reload), which are not safe to run concurrently. Acquired before
+	// m.mu; "*Locked" helpers assume it is held.
+	mutationMu    sync.Mutex
 	extensions    map[string]*loadedExtension
 	extensionsDir string
 	dataDir       string
@@ -156,8 +166,14 @@ func (m *extensionManager) SetDirectories(extensionsDir, dataDir string) error {
 }
 
 func (m *extensionManager) LoadExtensionFromFile(filePath string) (*loadedExtension, error) {
-	if !strings.HasSuffix(strings.ToLower(filePath), ".spotiflac-ext") {
-		return nil, fmt.Errorf("invalid file format: please select a .spotiflac-ext file")
+	m.mutationMu.Lock()
+	defer m.mutationMu.Unlock()
+	return m.loadExtensionFromFileLocked(filePath)
+}
+
+func (m *extensionManager) loadExtensionFromFileLocked(filePath string) (*loadedExtension, error) {
+	if !isExtensionPackagePath(filePath) {
+		return nil, fmt.Errorf("invalid file format: please select a .spotiflac-ext or .sflx file")
 	}
 
 	zipReader, err := zip.OpenReader(filePath)
@@ -212,7 +228,7 @@ func (m *extensionManager) LoadExtensionFromFile(filePath string) (*loadedExtens
 	if exists {
 		versionCompare := compareVersions(manifest.Version, existingVersion)
 		if versionCompare > 0 {
-			return m.UpgradeExtension(filePath)
+			return m.upgradeExtensionLocked(filePath)
 		} else if versionCompare == 0 {
 			return nil, fmt.Errorf("extension '%s' v%s is already installed", existingDisplayName, existingVersion)
 		} else {
@@ -296,6 +312,7 @@ func (m *extensionManager) LoadExtensionFromFile(filePath string) (*loadedExtens
 func initializeVMLocked(ext *loadedExtension) error {
 	ext.VM = nil
 	ext.runtime = nil
+	ext.indexProgram = nil
 	ext.initialized = false
 	vm := goja.New()
 	ext.VM = vm
@@ -305,6 +322,11 @@ func initializeVMLocked(ext *loadedExtension) error {
 	if err != nil {
 		return fmt.Errorf("failed to read index.js: %w", err)
 	}
+	indexProgram, err := goja.Compile(indexPath, string(jsCode), false)
+	if err != nil {
+		return fmt.Errorf("failed to compile extension code: %w", err)
+	}
+	ext.indexProgram = indexProgram
 
 	runtime := newExtensionRuntime(ext)
 	ext.runtime = runtime
@@ -331,7 +353,7 @@ func initializeVMLocked(ext *loadedExtension) error {
 		return goja.Undefined()
 	})
 
-	_, err = vm.RunString(string(jsCode))
+	_, err = vm.RunProgram(indexProgram)
 	if err != nil {
 		return fmt.Errorf("failed to execute extension code: %w", err)
 	}
@@ -346,10 +368,17 @@ func initializeVMLocked(ext *loadedExtension) error {
 func newIsolatedExtensionRuntime(ext *loadedExtension) (*goja.Runtime, *extensionRuntime, error) {
 	vm := goja.New()
 
-	indexPath := filepath.Join(ext.SourceDir, "index.js")
-	jsCode, err := os.ReadFile(indexPath)
-	if err != nil {
-		return nil, nil, fmt.Errorf("failed to read index.js: %w", err)
+	indexProgram := ext.indexProgram
+	if indexProgram == nil {
+		indexPath := filepath.Join(ext.SourceDir, "index.js")
+		jsCode, err := os.ReadFile(indexPath)
+		if err != nil {
+			return nil, nil, fmt.Errorf("failed to read index.js: %w", err)
+		}
+		indexProgram, err = goja.Compile(indexPath, string(jsCode), false)
+		if err != nil {
+			return nil, nil, fmt.Errorf("failed to compile extension code: %w", err)
+		}
 	}
 
 	runtime := &extensionRuntime{
@@ -392,7 +421,7 @@ func newIsolatedExtensionRuntime(ext *loadedExtension) (*goja.Runtime, *extensio
 		return goja.Undefined()
 	})
 
-	if _, err := vm.RunString(string(jsCode)); err != nil {
+	if _, err := vm.RunProgram(indexProgram); err != nil {
 		runtime.closeStorageFlusher()
 		return nil, nil, fmt.Errorf("failed to execute extension code: %w", err)
 	}
@@ -663,7 +692,7 @@ func (m *extensionManager) LoadExtensionsFromDirectory(dirPath string) ([]string
 					loaded = append(loaded, ext.ID)
 				}
 			}
-		} else if strings.HasSuffix(strings.ToLower(entry.Name()), ".spotiflac-ext") {
+		} else if isExtensionPackagePath(entry.Name()) {
 			ext, err := m.LoadExtensionFromFile(filepath.Join(dirPath, entry.Name()))
 			if err != nil {
 				GoLog("[Extension] Failed to load %s: %v\n", entry.Name(), err)
@@ -736,6 +765,9 @@ func (m *extensionManager) loadExtensionFromDirectory(dirPath string) (*loadedEx
 }
 
 func (m *extensionManager) RemoveExtension(extensionID string) error {
+	m.mutationMu.Lock()
+	defer m.mutationMu.Unlock()
+
 	ext, err := m.GetExtension(extensionID)
 	if err != nil {
 		return err
@@ -756,8 +788,14 @@ func (m *extensionManager) RemoveExtension(extensionID string) error {
 
 // Only allows upgrades (new version > current version), not downgrades
 func (m *extensionManager) UpgradeExtension(filePath string) (*loadedExtension, error) {
-	if !strings.HasSuffix(strings.ToLower(filePath), ".spotiflac-ext") {
-		return nil, fmt.Errorf("invalid file format: please select a .spotiflac-ext file")
+	m.mutationMu.Lock()
+	defer m.mutationMu.Unlock()
+	return m.upgradeExtensionLocked(filePath)
+}
+
+func (m *extensionManager) upgradeExtensionLocked(filePath string) (*loadedExtension, error) {
+	if !isExtensionPackagePath(filePath) {
+		return nil, fmt.Errorf("invalid file format: please select a .spotiflac-ext or .sflx file")
 	}
 
 	zipReader, err := zip.OpenReader(filePath)
@@ -905,8 +943,8 @@ type ExtensionUpgradeInfo struct {
 }
 
 func (m *extensionManager) checkExtensionUpgradeInternal(filePath string) (*ExtensionUpgradeInfo, error) {
-	if !strings.HasSuffix(strings.ToLower(filePath), ".spotiflac-ext") {
-		return nil, fmt.Errorf("invalid file format: please select a .spotiflac-ext file")
+	if !isExtensionPackagePath(filePath) {
+		return nil, fmt.Errorf("invalid file format: please select a .spotiflac-ext or .sflx file")
 	}
 
 	zipReader, err := zip.OpenReader(filePath)
@@ -1151,14 +1189,16 @@ func (m *extensionManager) InvokeAction(extensionID string, actionName string) (
 
 	// Merge extension return values onto the top-level JSON object so Flutter can read
 	// message, open_auth_url, setting_updates without unwrapping a nested "result" key.
+	actionNameLiteral := strconv.Quote(actionName)
 	script := fmt.Sprintf(`
-		(function() {
-			if (typeof extension !== 'undefined' && typeof extension.%s === 'function') {
-				try {
-					var result = extension.%s();
-					if (result && typeof result.then === 'function') {
-						return { success: true, pending: true, message: 'Action started' };
-					}
+			(function() {
+				var actionName = %s;
+				function runAction(fn) {
+					try {
+						var result = fn();
+						if (result && typeof result.then === 'function') {
+							return { success: true, pending: true, message: 'Action started' };
+						}
 					if (result !== null && result !== undefined && typeof result === 'object') {
 						var isArr = false;
 						if (typeof Array !== 'undefined' && Array.isArray) {
@@ -1173,13 +1213,19 @@ func (m *extensionManager) InvokeAction(extensionID string, actionName string) (
 						}
 					}
 					return { success: true, result: result };
-				} catch (e) {
-					return { success: false, error: e.toString() };
+					} catch (e) {
+						return { success: false, error: e.toString() };
+					}
 				}
-			}
-			return { success: false, error: 'Action function not found: %s' };
-		})()
-	`, actionName, actionName, actionName)
+				if (typeof extension !== 'undefined' && extension && typeof extension[actionName] === 'function') {
+					return runAction(function() { return extension[actionName](); });
+				}
+				if (actionName === 'completeGrant' && typeof session !== 'undefined' && session && typeof session.completeGrant === 'function') {
+					return runAction(function() { return session.completeGrant(); });
+				}
+				return { success: false, error: 'Action function not found: ' + actionName };
+			})()
+		`, actionNameLiteral)
 
 	result, err := RunWithTimeoutAndRecover(vm, script, DefaultJSTimeout)
 	if err != nil {

go_backend/extension_manifest.go

@@ -3,6 +3,7 @@ package gobackend
 import (
 	"encoding/json"
 	"fmt"
+	"net/url"
 	"strings"
 )
 
@@ -113,28 +114,49 @@ type ExtensionHealthCheck struct {
 	Required        bool   `json:"required,omitempty"`
 }
 
+type SignedSessionEndpoints struct {
+	Bootstrap string `json:"bootstrap,omitempty"`
+	Challenge string `json:"challenge,omitempty"`
+	Exchange  string `json:"exchange,omitempty"`
+	Refresh   string `json:"refresh,omitempty"`
+}
+
+type SignedSessionConfig struct {
+	Namespace         string                 `json:"namespace"`
+	BaseURL           string                 `json:"baseUrl"`
+	AppVersion        string                 `json:"appVersion,omitempty"`
+	Platform          string                 `json:"platform,omitempty"`
+	CallbackURL       string                 `json:"callbackUrl,omitempty"`
+	SchemeLabel       string                 `json:"schemeLabel,omitempty"`
+	HeaderPrefix      string                 `json:"headerPrefix,omitempty"`
+	TimeWindowSeconds int                    `json:"timeWindowSeconds,omitempty"`
+	Endpoints         SignedSessionEndpoints `json:"endpoints,omitempty"`
+}
+
 type ExtensionManifest struct {
-	Name                   string                 `json:"name"`
-	DisplayName            string                 `json:"displayName"`
-	Version                string                 `json:"version"`
-	Description            string                 `json:"description"`
-	Homepage               string                 `json:"homepage,omitempty"`
-	Icon                   string                 `json:"icon,omitempty"`
-	Types                  []ExtensionType        `json:"type"`
-	Permissions            ExtensionPermissions   `json:"permissions"`
-	Settings               []ExtensionSetting     `json:"settings,omitempty"`
-	QualityOptions         []QualityOption        `json:"qualityOptions,omitempty"`
-	MinAppVersion          string                 `json:"minAppVersion,omitempty"`
-	SkipMetadataEnrichment bool                   `json:"skipMetadataEnrichment,omitempty"`
-	SkipLyrics             bool                   `json:"skipLyrics,omitempty"`
-	StopProviderFallback   bool                   `json:"stopProviderFallback,omitempty"`
-	SkipBuiltInFallback    bool                   `json:"skipBuiltInFallback,omitempty"`
-	SearchBehavior         *SearchBehaviorConfig  `json:"searchBehavior,omitempty"`
-	URLHandler             *URLHandlerConfig      `json:"urlHandler,omitempty"`
-	TrackMatching          *TrackMatchingConfig   `json:"trackMatching,omitempty"`
-	PostProcessing         *PostProcessingConfig  `json:"postProcessing,omitempty"`
-	ServiceHealth          []ExtensionHealthCheck `json:"serviceHealth,omitempty"`
-	Capabilities           map[string]interface{} `json:"capabilities,omitempty"`
+	Name                    string                 `json:"name"`
+	DisplayName             string                 `json:"displayName"`
+	Version                 string                 `json:"version"`
+	Description             string                 `json:"description"`
+	Homepage                string                 `json:"homepage,omitempty"`
+	Icon                    string                 `json:"icon,omitempty"`
+	Types                   []ExtensionType        `json:"type"`
+	Permissions             ExtensionPermissions   `json:"permissions"`
+	Settings                []ExtensionSetting     `json:"settings,omitempty"`
+	QualityOptions          []QualityOption        `json:"qualityOptions,omitempty"`
+	MinAppVersion           string                 `json:"minAppVersion,omitempty"`
+	SkipMetadataEnrichment  bool                   `json:"skipMetadataEnrichment,omitempty"`
+	SkipLyrics              bool                   `json:"skipLyrics,omitempty"`
+	StopProviderFallback    bool                   `json:"stopProviderFallback,omitempty"`
+	SkipBuiltInFallback     bool                   `json:"skipBuiltInFallback,omitempty"`
+	SearchBehavior          *SearchBehaviorConfig  `json:"searchBehavior,omitempty"`
+	URLHandler              *URLHandlerConfig      `json:"urlHandler,omitempty"`
+	TrackMatching           *TrackMatchingConfig   `json:"trackMatching,omitempty"`
+	PostProcessing          *PostProcessingConfig  `json:"postProcessing,omitempty"`
+	ServiceHealth           []ExtensionHealthCheck `json:"serviceHealth,omitempty"`
+	SignedSession           *SignedSessionConfig   `json:"signedSession,omitempty"`
+	RequiredRuntimeFeatures []string               `json:"requiredRuntimeFeatures,omitempty"`
+	Capabilities            map[string]interface{} `json:"capabilities,omitempty"`
 }
 
 type ManifestValidationError struct {
@@ -200,7 +222,6 @@ func (m *ExtensionManifest) Validate() error {
 			}
 		}
 
-		// Select type requires options
 		if setting.Type == SettingTypeSelect && len(setting.Options) == 0 {
 			return &ManifestValidationError{
 				Field:   fmt.Sprintf("settings[%d].options", i),
@@ -238,6 +259,26 @@ func (m *ExtensionManifest) Validate() error {
 		}
 	}
 
+	if m.SignedSession != nil {
+		if strings.TrimSpace(m.SignedSession.Namespace) == "" {
+			return &ManifestValidationError{Field: "signedSession.namespace", Message: "namespace is required"}
+		}
+		baseURL := strings.TrimSpace(m.SignedSession.BaseURL)
+		if baseURL == "" {
+			return &ManifestValidationError{Field: "signedSession.baseUrl", Message: "baseUrl is required"}
+		}
+		if !strings.HasPrefix(strings.ToLower(baseURL), "https://") {
+			return &ManifestValidationError{Field: "signedSession.baseUrl", Message: "baseUrl must use https"}
+		}
+		parsed, err := url.Parse(baseURL)
+		if err != nil || parsed.Hostname() == "" {
+			return &ManifestValidationError{Field: "signedSession.baseUrl", Message: "baseUrl is invalid"}
+		}
+		if !m.IsDomainAllowed(parsed.Hostname()) {
+			return &ManifestValidationError{Field: "signedSession.baseUrl", Message: "baseUrl host must be listed in permissions.network"}
+		}
+	}
+
 	return nil
 }
 

go_backend/extension_providers.go

@@ -29,6 +29,7 @@ type ExtTrackMetadata struct {
 	ExternalURL string `json:"external_urls,omitempty"`
 	DurationMS  int    `json:"duration_ms"`
 	CoverURL    string `json:"cover_url,omitempty"`
+	PreviewURL  string `json:"preview_url,omitempty"`
 	Images      string `json:"images,omitempty"`
 	ReleaseDate string `json:"release_date,omitempty"`
 	TrackNumber int    `json:"track_number,omitempty"`
@@ -68,9 +69,12 @@ type ExtAlbumMetadata struct {
 	Artists     string             `json:"artists"`
 	ArtistID    string             `json:"artist_id,omitempty"`
 	CoverURL    string             `json:"cover_url,omitempty"`
+	HeaderImage string             `json:"header_image,omitempty"`
+	HeaderVideo string             `json:"header_video,omitempty"`
 	ReleaseDate string             `json:"release_date,omitempty"`
 	TotalTracks int                `json:"total_tracks"`
 	AlbumType   string             `json:"album_type,omitempty"`
+	AudioTraits []string           `json:"audio_traits,omitempty"`
 	Tracks      []ExtTrackMetadata `json:"tracks"`
 	ProviderID  string             `json:"provider_id"`
 }
@@ -80,6 +84,7 @@ type ExtArtistMetadata struct {
 	Name        string             `json:"name"`
 	ImageURL    string             `json:"image_url,omitempty"`
 	HeaderImage string             `json:"header_image,omitempty"`
+	HeaderVideo string             `json:"header_video,omitempty"`
 	Listeners   int                `json:"listeners,omitempty"`
 	Albums      []ExtAlbumMetadata `json:"albums,omitempty"`
 	Releases    []ExtAlbumMetadata `json:"releases,omitempty"`
@@ -473,6 +478,18 @@ func shouldAbortCancelledFallback(itemID string, err error) bool {
 	return itemID != "" && isDownloadCancelled(itemID)
 }
 
+func normalizeExtensionDownloadErrorType(errorType, message string) string {
+	normalized := strings.TrimSpace(errorType)
+	classified := classifyDownloadErrorType(message)
+	if classified != "" && classified != "unknown" {
+		switch strings.ToLower(normalized) {
+		case "", "unknown", "runtime_error", "api_error", "download_error", "extension_error":
+			return classified
+		}
+	}
+	return normalized
+}
+
 type DownloadDecryptionInfo struct {
 	Strategy        string                 `json:"strategy,omitempty"`
 	Key             string                 `json:"key,omitempty"`
@@ -483,14 +500,15 @@ type DownloadDecryptionInfo struct {
 }
 
 type ExtDownloadResult struct {
-	Success       bool   `json:"success"`
-	FilePath      string `json:"file_path,omitempty"`
-	AlreadyExists bool   `json:"already_exists,omitempty"`
-	BitDepth      int    `json:"bit_depth,omitempty"`
-	SampleRate    int    `json:"sample_rate,omitempty"`
-	AudioCodec    string `json:"audio_codec,omitempty"`
-	ErrorMessage  string `json:"error_message,omitempty"`
-	ErrorType     string `json:"error_type,omitempty"`
+	Success           bool   `json:"success"`
+	FilePath          string `json:"file_path,omitempty"`
+	AlreadyExists     bool   `json:"already_exists,omitempty"`
+	BitDepth          int    `json:"bit_depth,omitempty"`
+	SampleRate        int    `json:"sample_rate,omitempty"`
+	AudioCodec        string `json:"audio_codec,omitempty"`
+	ErrorMessage      string `json:"error_message,omitempty"`
+	ErrorType         string `json:"error_type,omitempty"`
+	RetryAfterSeconds int    `json:"retry_after_seconds,omitempty"`
 
 	Title                       string                  `json:"title,omitempty"`
 	Artist                      string                  `json:"artist,omitempty"`
@@ -724,6 +742,32 @@ func gojaObjectStringMap(vm *goja.Runtime, obj *goja.Object, keys ...string) map
 	return result
 }
 
+func gojaObjectStringSlice(obj *goja.Object, keys ...string) []string {
+	value := gojaObjectValue(obj, keys...)
+	if gojaValueIsEmpty(value) {
+		return nil
+	}
+	exported, ok := value.Export().([]interface{})
+	if !ok || len(exported) == 0 {
+		return nil
+	}
+	result := make([]string, 0, len(exported))
+	for _, item := range exported {
+		str, ok := item.(string)
+		if !ok {
+			continue
+		}
+		str = strings.TrimSpace(str)
+		if str != "" {
+			result = append(result, str)
+		}
+	}
+	if len(result) == 0 {
+		return nil
+	}
+	return result
+}
+
 func gojaArrayLength(value goja.Value, vm *goja.Runtime) (int, error) {
 	if gojaValueIsEmpty(value) {
 		return 0, nil
@@ -754,6 +798,7 @@ func parseExtensionTrackValue(vm *goja.Runtime, value goja.Value) ExtTrackMetada
 		ExternalURL:   gojaObjectString(obj, "external_urls", "externalUrls", "external_url", "externalUrl", "url"),
 		DurationMS:    gojaObjectInt(obj, "duration_ms", "durationMs"),
 		CoverURL:      gojaObjectString(obj, "cover_url", "coverUrl"),
+		PreviewURL:    gojaObjectString(obj, "preview_url", "previewUrl"),
 		Images:        gojaObjectString(obj, "images"),
 		ReleaseDate:   gojaObjectString(obj, "release_date", "releaseDate"),
 		TrackNumber:   gojaObjectInt(obj, "track_number", "trackNumber"),
@@ -820,12 +865,147 @@ func parseExtensionAlbumValue(vm *goja.Runtime, value goja.Value) (ExtAlbumMetad
 		Artists:     gojaObjectString(obj, "artists"),
 		ArtistID:    gojaObjectString(obj, "artist_id", "artistId"),
 		CoverURL:    gojaObjectString(obj, "cover_url", "coverUrl", "images"),
+		HeaderImage: gojaObjectString(obj, "header_image", "headerImage"),
+		HeaderVideo: gojaObjectString(obj, "header_video", "headerVideo"),
 		ReleaseDate: gojaObjectString(obj, "release_date", "releaseDate"),
 		TotalTracks: gojaObjectInt(obj, "total_tracks", "totalTracks"),
 		AlbumType:   gojaObjectString(obj, "album_type", "albumType"),
+		AudioTraits: gojaObjectStringSlice(obj, "audio_traits", "audioTraits"),
 		Tracks:      tracks,
 		ProviderID:  gojaObjectString(obj, "provider_id", "providerId"),
-	}, nil
+	}.withTrackFallbacks(), nil
+}
+
+// withTrackFallbacks fills the album-level artist and release date from the
+// album's tracks when the extension did not provide them at the album level.
+// This is a generic mechanism so any extension benefits, without per-extension
+// special-casing in the app.
+func (a ExtAlbumMetadata) withTrackFallbacks() ExtAlbumMetadata {
+	if strings.TrimSpace(a.Artists) == "" {
+		a.Artists = albumArtistFromTracks(a.Tracks)
+	}
+	if strings.TrimSpace(a.ReleaseDate) == "" {
+		a.ReleaseDate = albumReleaseDateFromTracks(a.Tracks)
+	}
+	if len(a.AudioTraits) == 0 {
+		a.AudioTraits = albumAudioTraitsFromTracks(a.Tracks)
+	}
+	return a
+}
+
+// albumArtistFromTracks prefers an explicit per-track album artist, then falls
+// back to the most common track artist across the album.
+func albumArtistFromTracks(tracks []ExtTrackMetadata) string {
+	for _, t := range tracks {
+		if s := strings.TrimSpace(t.AlbumArtist); s != "" {
+			return s
+		}
+	}
+	counts := map[string]int{}
+	order := []string{}
+	for _, t := range tracks {
+		artist := strings.TrimSpace(t.Artists)
+		if artist == "" {
+			continue
+		}
+		if _, ok := counts[artist]; !ok {
+			order = append(order, artist)
+		}
+		counts[artist]++
+	}
+	best := ""
+	bestCount := 0
+	for _, artist := range order {
+		if counts[artist] > bestCount {
+			best = artist
+			bestCount = counts[artist]
+		}
+	}
+	return best
+}
+
+// albumReleaseDateFromTracks returns the first non-empty track release date.
+func albumReleaseDateFromTracks(tracks []ExtTrackMetadata) string {
+	for _, t := range tracks {
+		if s := strings.TrimSpace(t.ReleaseDate); s != "" {
+			return s
+		}
+	}
+	return ""
+}
+
+// albumAudioTraitsFromTracks derives album-level audio badges (Dolby Atmos,
+// Hi-Res Lossless, Lossless) from the per-track audio quality/mode fields that
+// extensions like Tidal and Qobuz already provide. Tokens match what the album
+// header understands ("dolby_atmos", "hi_res_lossless", "lossless").
+func albumAudioTraitsFromTracks(tracks []ExtTrackMetadata) []string {
+	atmos := false
+	hiRes := false
+	lossless := false
+
+	for _, t := range tracks {
+		modes := strings.ToUpper(t.AudioModes)
+		quality := strings.ToUpper(t.AudioQuality)
+		if strings.Contains(modes, "ATMOS") || strings.Contains(quality, "ATMOS") {
+			atmos = true
+		}
+		if strings.Contains(quality, "HI_RES") ||
+			strings.Contains(quality, "HIRES") ||
+			strings.Contains(quality, "MASTER") ||
+			strings.Contains(quality, "MQA") {
+			hiRes = true
+		}
+		if strings.Contains(quality, "LOSSLESS") ||
+			strings.Contains(quality, "FLAC") {
+			lossless = true
+		}
+		if bd, sr := parseBitDepthSampleRate(quality); bd > 0 {
+			if bd > 16 || sr > 48 {
+				hiRes = true
+			} else {
+				lossless = true
+			}
+		}
+	}
+
+	traits := []string{}
+	if atmos {
+		traits = append(traits, "dolby_atmos")
+	}
+	if hiRes {
+		traits = append(traits, "hi_res_lossless")
+	} else if lossless {
+		traits = append(traits, "lossless")
+	}
+	return traits
+}
+
+// parseBitDepthSampleRate extracts a bit depth and sample rate (in kHz) from
+// labels such as "24bit/96kHz", "16bit/44.1kHz" or "24bit".
+func parseBitDepthSampleRate(quality string) (int, float64) {
+	lower := strings.ToLower(quality)
+	bitDepth := 0
+	sampleRate := 0.0
+
+	if idx := strings.Index(lower, "bit"); idx > 0 {
+		j := idx
+		for j > 0 && lower[j-1] >= '0' && lower[j-1] <= '9' {
+			j--
+		}
+		if n, err := strconv.Atoi(lower[j:idx]); err == nil {
+			bitDepth = n
+		}
+	}
+	if idx := strings.Index(lower, "khz"); idx > 0 {
+		j := idx
+		for j > 0 && ((lower[j-1] >= '0' && lower[j-1] <= '9') || lower[j-1] == '.') {
+			j--
+		}
+		if f, err := strconv.ParseFloat(lower[j:idx], 64); err == nil {
+			sampleRate = f
+		}
+	}
+	return bitDepth, sampleRate
 }
 
 func parseExtensionAlbumArray(vm *goja.Runtime, value goja.Value) ([]ExtAlbumMetadata, error) {
@@ -891,6 +1071,7 @@ func parseExtensionArtistValue(vm *goja.Runtime, value goja.Value) (ExtArtistMet
 		Name:        gojaObjectString(obj, "name"),
 		ImageURL:    gojaObjectString(obj, "image_url", "imageUrl"),
 		HeaderImage: gojaObjectString(obj, "header_image", "headerImage"),
+		HeaderVideo: gojaObjectString(obj, "header_video", "headerVideo"),
 		Listeners:   gojaObjectInt(obj, "listeners"),
 		Albums:      albums,
 		Releases:    releases,
@@ -942,35 +1123,36 @@ func parseExtensionDownloadDecryptionValue(vm *goja.Runtime, value goja.Value) *
 func parseExtensionDownloadResultValue(vm *goja.Runtime, value goja.Value) ExtDownloadResult {
 	obj := value.ToObject(vm)
 	return ExtDownloadResult{
-		Success:         gojaObjectBool(obj, "success"),
-		FilePath:        gojaObjectString(obj, "file_path", "filePath", "path"),
-		AlreadyExists:   gojaObjectBool(obj, "already_exists", "alreadyExists"),
-		BitDepth:        gojaObjectInt(obj, "bit_depth", "bitDepth"),
-		SampleRate:      gojaObjectInt(obj, "sample_rate", "sampleRate"),
-		AudioCodec:      gojaObjectString(obj, "audio_codec", "audioCodec", "codec"),
-		ErrorMessage:    gojaObjectString(obj, "error_message", "errorMessage", "error"),
-		ErrorType:       gojaObjectString(obj, "error_type", "errorType"),
-		Title:           gojaObjectString(obj, "title"),
-		Artist:          gojaObjectString(obj, "artist"),
-		Album:           gojaObjectString(obj, "album"),
-		AlbumArtist:     gojaObjectString(obj, "album_artist", "albumArtist"),
-		TrackNumber:     gojaObjectInt(obj, "track_number", "trackNumber"),
-		DiscNumber:      gojaObjectInt(obj, "disc_number", "discNumber"),
-		TotalTracks:     gojaObjectInt(obj, "total_tracks", "totalTracks"),
-		TotalDiscs:      gojaObjectInt(obj, "total_discs", "totalDiscs"),
-		ReleaseDate:     gojaObjectString(obj, "release_date", "releaseDate"),
-		CoverURL:        gojaObjectString(obj, "cover_url", "coverUrl"),
-		ISRC:            gojaObjectString(obj, "isrc"),
-		Genre:           gojaObjectString(obj, "genre"),
-		Label:           gojaObjectString(obj, "label"),
-		Copyright:       gojaObjectString(obj, "copyright"),
-		Composer:        gojaObjectString(obj, "composer"),
-		LyricsLRC:       gojaObjectString(obj, "lyrics_lrc", "lyricsLrc"),
-		DecryptionKey:   gojaObjectString(obj, "decryption_key", "decryptionKey"),
-		Decryption:      parseExtensionDownloadDecryptionValue(vm, gojaObjectValue(obj, "decryption")),
-		ActualExtension: gojaObjectString(obj, "actual_extension", "actualExtension"),
-		OutputExtension: gojaObjectString(obj, "output_extension", "outputExtension"),
-		ActualContainer: gojaObjectString(obj, "actual_container", "actualContainer", "container"),
+		Success:           gojaObjectBool(obj, "success"),
+		FilePath:          gojaObjectString(obj, "file_path", "filePath", "path"),
+		AlreadyExists:     gojaObjectBool(obj, "already_exists", "alreadyExists"),
+		BitDepth:          gojaObjectInt(obj, "bit_depth", "bitDepth"),
+		SampleRate:        gojaObjectInt(obj, "sample_rate", "sampleRate"),
+		AudioCodec:        gojaObjectString(obj, "audio_codec", "audioCodec", "codec"),
+		ErrorMessage:      gojaObjectString(obj, "error_message", "errorMessage", "error"),
+		ErrorType:         gojaObjectString(obj, "error_type", "errorType"),
+		RetryAfterSeconds: gojaObjectInt(obj, "retry_after_seconds", "retryAfterSeconds"),
+		Title:             gojaObjectString(obj, "title"),
+		Artist:            gojaObjectString(obj, "artist"),
+		Album:             gojaObjectString(obj, "album"),
+		AlbumArtist:       gojaObjectString(obj, "album_artist", "albumArtist"),
+		TrackNumber:       gojaObjectInt(obj, "track_number", "trackNumber"),
+		DiscNumber:        gojaObjectInt(obj, "disc_number", "discNumber"),
+		TotalTracks:       gojaObjectInt(obj, "total_tracks", "totalTracks"),
+		TotalDiscs:        gojaObjectInt(obj, "total_discs", "totalDiscs"),
+		ReleaseDate:       gojaObjectString(obj, "release_date", "releaseDate"),
+		CoverURL:          gojaObjectString(obj, "cover_url", "coverUrl"),
+		ISRC:              gojaObjectString(obj, "isrc"),
+		Genre:             gojaObjectString(obj, "genre"),
+		Label:             gojaObjectString(obj, "label"),
+		Copyright:         gojaObjectString(obj, "copyright"),
+		Composer:          gojaObjectString(obj, "composer"),
+		LyricsLRC:         gojaObjectString(obj, "lyrics_lrc", "lyricsLrc"),
+		DecryptionKey:     gojaObjectString(obj, "decryption_key", "decryptionKey"),
+		Decryption:        parseExtensionDownloadDecryptionValue(vm, gojaObjectValue(obj, "decryption")),
+		ActualExtension:   gojaObjectString(obj, "actual_extension", "actualExtension"),
+		OutputExtension:   gojaObjectString(obj, "output_extension", "outputExtension"),
+		ActualContainer:   gojaObjectString(obj, "actual_container", "actualContainer", "container"),
 		RequiresContainerConversion: gojaObjectBool(
 			obj,
 			"requires_container_conversion",
@@ -982,9 +1164,11 @@ func parseExtensionDownloadResultValue(vm *goja.Runtime, value goja.Value) ExtDo
 func parseExtensionURLHandleValue(vm *goja.Runtime, value goja.Value) (ExtURLHandleResult, error) {
 	obj := value.ToObject(vm)
 	handleResult := ExtURLHandleResult{
-		Type:     gojaObjectString(obj, "type"),
-		Name:     gojaObjectString(obj, "name"),
-		CoverURL: gojaObjectString(obj, "cover_url", "coverUrl"),
+		Type:        gojaObjectString(obj, "type"),
+		Name:        gojaObjectString(obj, "name"),
+		CoverURL:    gojaObjectString(obj, "cover_url", "coverUrl"),
+		HeaderImage: gojaObjectString(obj, "header_image", "headerImage"),
+		HeaderVideo: gojaObjectString(obj, "header_video", "headerVideo"),
 	}
 
 	if trackValue := gojaObjectValue(obj, "track"); !gojaValueIsEmpty(trackValue) {
@@ -2135,6 +2319,8 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 	}
 
 	var lastErr error
+	var lastErrType string
+	var lastRetryAfterSeconds int
 	var stopProviderFallback bool
 	var sourceExtensionLocked bool
 	var sourceExtensionAvailability *ExtAvailabilityResult
@@ -2416,15 +2602,7 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 					resp.Composer = req.Composer
 				}
 
-				if !alreadyExists && req.EmbedMetadata && (req.Genre != "" || req.Label != "") && canEmbedGenreLabel(normalizedResult.FilePath) {
-					if err := EmbedGenreLabel(normalizedResult.FilePath, req.Genre, req.Label); err != nil {
-						GoLog("[DownloadWithExtensionFallback] Warning: failed to embed genre/label: %v\n", err)
-					} else {
-						GoLog("[DownloadWithExtensionFallback] Embedded genre=%q label=%q\n", req.Genre, req.Label)
-					}
-				} else if !alreadyExists && req.EmbedMetadata && (req.Genre != "" || req.Label != "") {
-					GoLog("[DownloadWithExtensionFallback] Skipping genre/label embed for non-local output path: %q\n", normalizedResult.FilePath)
-				}
+				embedExtensionDownloadMetadata(resp, req, alreadyExists)
 
 				if !alreadyExists && !isFDOutput(req.OutputFD) && strings.TrimSpace(req.OutputDir) != "" {
 					indexISRC := strings.TrimSpace(resp.ISRC)
@@ -2449,11 +2627,24 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 					}, nil
 				}
 				lastErr = err
+				lastErrType = ""
 			} else if result.ErrorMessage != "" {
 				lastErr = fmt.Errorf("%s", result.ErrorMessage)
+				lastErrType = normalizeExtensionDownloadErrorType(result.ErrorType, result.ErrorMessage)
+				lastRetryAfterSeconds = result.RetryAfterSeconds
 			}
 			GoLog("[DownloadWithExtensionFallback] Source extension %s failed: %v\n", req.Source, lastErr)
 
+			if strings.EqualFold(lastErrType, "verification_required") {
+				GoLog("[DownloadWithExtensionFallback] Source extension %s requires verification, not trying other providers\n", req.Source)
+				return &DownloadResponse{
+					Success:   false,
+					Error:     "Download failed: " + lastErr.Error(),
+					ErrorType: "verification_required",
+					Service:   req.Source,
+				}, nil
+			}
+
 			if stopProviderFallback || sourceExtensionLocked {
 				if sourceExtensionLocked {
 					GoLog("[DownloadWithExtensionFallback] Source extension %s requested skip_fallback, not trying other providers\n", req.Source)
@@ -2461,10 +2652,11 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 				}
 				GoLog("[DownloadWithExtensionFallback] stopProviderFallback is true, not trying other providers\n")
 				return &DownloadResponse{
-					Success:   false,
-					Error:     "Download failed: " + lastErr.Error(),
-					ErrorType: "extension_error",
-					Service:   req.Source,
+					Success:           false,
+					Error:             "Download failed: " + lastErr.Error(),
+					ErrorType:         firstNonEmptyString(lastErrType, "extension_error"),
+					RetryAfterSeconds: lastRetryAfterSeconds,
+					Service:           req.Source,
 				}, nil
 			}
 		} else {
@@ -2483,11 +2675,13 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 		if providerID == "" {
 			continue
 		}
-		if providerID == req.Source {
+		// Skip the origin extension only when it differs from the explicitly
+		// selected provider; otherwise it must still be attempted here.
+		if providerID == req.Source && req.Source != selectedProvider {
 			continue
 		}
 
-		if !isExtensionFallbackAllowed(providerID) {
+		if providerID != selectedProvider && !isExtensionFallbackAllowed(providerID) {
 			GoLog("[DownloadWithExtensionFallback] Skipping extension provider %s (not enabled for fallback)\n", providerID)
 			continue
 		}
@@ -2516,6 +2710,15 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 				GoLog("[DownloadWithExtensionFallback] %s: not available\n", providerID)
 				if err != nil {
 					lastErr = err
+					if strings.EqualFold(classifyDownloadErrorType(err.Error()), "verification_required") {
+						GoLog("[DownloadWithExtensionFallback] %s requires verification (availability); pausing fallback to open the challenge\n", providerID)
+						return &DownloadResponse{
+							Success:   false,
+							Error:     "Download failed: " + err.Error(),
+							ErrorType: "verification_required",
+							Service:   providerID,
+						}, nil
+					}
 				}
 				if terminalAvailability {
 					GoLog("[DownloadWithExtensionFallback] %s requested skip_fallback after availability check\n", providerID)
@@ -2530,7 +2733,30 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 				StartItemProgress(req.ItemID)
 			}
 
-			result, err := provider.Download(availability.TrackID, req.Quality, outputPath, req.ItemID, func(percent int) {
+			// Honor the requested quality when this provider recognizes it
+			// (e.g. an explicit user selection). Only when the token is not
+			// one of this provider's own options do we fall back to its
+			// highest quality, since a source provider's token may not map.
+			fallbackQuality := req.Quality
+			if len(ext.Manifest.QualityOptions) > 0 {
+				requested := strings.TrimSpace(req.Quality)
+				recognized := false
+				if requested != "" {
+					for _, opt := range ext.Manifest.QualityOptions {
+						if strings.EqualFold(strings.TrimSpace(opt.ID), requested) {
+							recognized = true
+							break
+						}
+					}
+				}
+				if !recognized {
+					if best := strings.TrimSpace(ext.Manifest.QualityOptions[0].ID); best != "" {
+						fallbackQuality = best
+					}
+				}
+			}
+
+			result, err := provider.Download(availability.TrackID, fallbackQuality, outputPath, req.ItemID, func(percent int) {
 				if req.ItemID != "" {
 					normalized := float64(percent) / 100.0
 					if normalized < 0 {
@@ -2574,15 +2800,7 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 				}
 				applyExtensionRequestFallbacks(&resp, req)
 
-				if !alreadyExists && req.EmbedMetadata && (req.Genre != "" || req.Label != "") && canEmbedGenreLabel(normalizedResult.FilePath) {
-					if err := EmbedGenreLabel(normalizedResult.FilePath, req.Genre, req.Label); err != nil {
-						GoLog("[DownloadWithExtensionFallback] Warning: failed to embed genre/label: %v\n", err)
-					} else {
-						GoLog("[DownloadWithExtensionFallback] Embedded genre=%q label=%q\n", req.Genre, req.Label)
-					}
-				} else if !alreadyExists && req.EmbedMetadata && (req.Genre != "" || req.Label != "") {
-					GoLog("[DownloadWithExtensionFallback] Skipping genre/label embed for non-local output path: %q\n", normalizedResult.FilePath)
-				}
+				embedExtensionDownloadMetadata(resp, req, alreadyExists)
 
 				if !alreadyExists && !isFDOutput(req.OutputFD) && strings.TrimSpace(req.OutputDir) != "" {
 					indexISRC := strings.TrimSpace(resp.ISRC)
@@ -2607,10 +2825,31 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 					}, nil
 				}
 				lastErr = err
+				lastErrType = ""
 			} else if result.ErrorMessage != "" {
 				lastErr = fmt.Errorf("%s", result.ErrorMessage)
+				lastErrType = normalizeExtensionDownloadErrorType(result.ErrorType, result.ErrorMessage)
+				lastRetryAfterSeconds = result.RetryAfterSeconds
 			}
 			GoLog("[DownloadWithExtensionFallback] %s failed: %v\n", providerID, lastErr)
+
+			if lastErr != nil {
+				effType := lastErrType
+				if effType == "" {
+					effType = classifyDownloadErrorType(lastErr.Error())
+				}
+				if strings.EqualFold(effType, "verification_required") {
+					GoLog("[DownloadWithExtensionFallback] %s requires verification; pausing fallback to open the challenge\n", providerID)
+					return &DownloadResponse{
+						Success:           false,
+						Error:             "Download failed: " + lastErr.Error(),
+						ErrorType:         "verification_required",
+						RetryAfterSeconds: lastRetryAfterSeconds,
+						Service:           providerID,
+					}, nil
+				}
+			}
+
 			if terminalAvailability {
 				GoLog("[DownloadWithExtensionFallback] %s requested skip_fallback after download failure\n", providerID)
 				return buildExtensionFallbackStoppedResponse(providerID, availability, lastErr), nil
@@ -2619,14 +2858,15 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 	}
 
 	if lastErr != nil {
-		errorType := classifyDownloadErrorType(lastErr.Error())
+		errorType := firstNonEmptyString(lastErrType, classifyDownloadErrorType(lastErr.Error()))
 		if errorType == "unknown" {
 			errorType = "not_found"
 		}
 		return &DownloadResponse{
-			Success:   false,
-			Error:     "All providers failed. Last error: " + lastErr.Error(),
-			ErrorType: errorType,
+			Success:           false,
+			Error:             "All providers failed. Last error: " + lastErr.Error(),
+			ErrorType:         errorType,
+			RetryAfterSeconds: lastRetryAfterSeconds,
 		}, nil
 	}
 
@@ -2643,21 +2883,22 @@ func buildOutputPath(req DownloadRequest) string {
 	}
 
 	metadata := map[string]interface{}{
-		"title":        req.TrackName,
-		"artist":       req.ArtistName,
-		"album":        req.AlbumName,
-		"album_artist": req.AlbumArtist,
-		"track":        req.TrackNumber,
-		"track_number": req.TrackNumber,
-		"total_tracks": req.TotalTracks,
-		"disc":         req.DiscNumber,
-		"disc_number":  req.DiscNumber,
-		"total_discs":  req.TotalDiscs,
-		"year":         extractYear(req.ReleaseDate),
-		"date":         req.ReleaseDate,
-		"release_date": req.ReleaseDate,
-		"isrc":         req.ISRC,
-		"composer":     req.Composer,
+		"title":             req.TrackName,
+		"artist":            req.ArtistName,
+		"album":             req.AlbumName,
+		"album_artist":      req.AlbumArtist,
+		"track":             req.TrackNumber,
+		"track_number":      req.TrackNumber,
+		"total_tracks":      req.TotalTracks,
+		"playlist_position": req.PlaylistPosition,
+		"disc":              req.DiscNumber,
+		"disc_number":       req.DiscNumber,
+		"total_discs":       req.TotalDiscs,
+		"year":              extractYear(req.ReleaseDate),
+		"date":              req.ReleaseDate,
+		"release_date":      req.ReleaseDate,
+		"isrc":              req.ISRC,
+		"composer":          req.Composer,
 	}
 
 	filename := buildFilenameFromTemplate(req.FilenameFormat, metadata)
@@ -2702,21 +2943,22 @@ func buildOutputPathForExtension(req DownloadRequest, ext *loadedExtension) stri
 	AddAllowedDownloadDir(tempDir)
 
 	metadata := map[string]interface{}{
-		"title":        req.TrackName,
-		"artist":       req.ArtistName,
-		"album":        req.AlbumName,
-		"album_artist": req.AlbumArtist,
-		"track":        req.TrackNumber,
-		"track_number": req.TrackNumber,
-		"total_tracks": req.TotalTracks,
-		"disc":         req.DiscNumber,
-		"disc_number":  req.DiscNumber,
-		"total_discs":  req.TotalDiscs,
-		"year":         extractYear(req.ReleaseDate),
-		"date":         req.ReleaseDate,
-		"release_date": req.ReleaseDate,
-		"isrc":         req.ISRC,
-		"composer":     req.Composer,
+		"title":             req.TrackName,
+		"artist":            req.ArtistName,
+		"album":             req.AlbumName,
+		"album_artist":      req.AlbumArtist,
+		"track":             req.TrackNumber,
+		"track_number":      req.TrackNumber,
+		"total_tracks":      req.TotalTracks,
+		"playlist_position": req.PlaylistPosition,
+		"disc":              req.DiscNumber,
+		"disc_number":       req.DiscNumber,
+		"total_discs":       req.TotalDiscs,
+		"year":              extractYear(req.ReleaseDate),
+		"date":              req.ReleaseDate,
+		"release_date":      req.ReleaseDate,
+		"isrc":              req.ISRC,
+		"composer":          req.Composer,
 	}
 
 	filename := buildFilenameFromTemplate(req.FilenameFormat, metadata)
@@ -2750,6 +2992,78 @@ func canEmbedGenreLabel(filePath string) bool {
 	return err == nil && !info.IsDir() && info.Size() > 0
 }
 
+func embedExtensionDownloadMetadata(resp DownloadResponse, req DownloadRequest, alreadyExists bool) {
+	if alreadyExists || !req.EmbedMetadata {
+		return
+	}
+
+	filePath := strings.TrimSpace(resp.FilePath)
+	if !canEmbedGenreLabel(filePath) {
+		if req.Genre != "" || req.Label != "" || resp.CoverURL != "" || req.CoverURL != "" {
+			GoLog("[DownloadWithExtensionFallback] Skipping metadata/cover embed for non-local FLAC output path: %q\n", filePath)
+		}
+		return
+	}
+
+	coverURL := firstNonEmptyTrimmed(resp.CoverURL, req.CoverURL)
+	var coverData []byte
+	if coverURL != "" {
+		data, err := downloadCoverToMemory(coverURL, req.EmbedMaxQualityCover)
+		if err != nil {
+			GoLog("[DownloadWithExtensionFallback] Warning: failed to download cover for metadata embed: %v\n", err)
+		} else if len(data) > 0 {
+			coverData = data
+		}
+	}
+
+	metadata := Metadata{
+		Title:         firstNonEmptyTrimmed(resp.Title, req.TrackName),
+		Artist:        firstNonEmptyTrimmed(resp.Artist, req.ArtistName),
+		Album:         firstNonEmptyTrimmed(resp.Album, req.AlbumName),
+		AlbumArtist:   firstNonEmptyTrimmed(resp.AlbumArtist, req.AlbumArtist),
+		ArtistTagMode: req.ArtistTagMode,
+		Date:          firstNonEmptyTrimmed(resp.ReleaseDate, req.ReleaseDate),
+		TrackNumber:   firstPositiveInt(resp.TrackNumber, req.TrackNumber),
+		TotalTracks:   firstPositiveInt(resp.TotalTracks, req.TotalTracks),
+		DiscNumber:    firstPositiveInt(resp.DiscNumber, req.DiscNumber),
+		TotalDiscs:    firstPositiveInt(resp.TotalDiscs, req.TotalDiscs),
+		ISRC:          firstNonEmptyTrimmed(resp.ISRC, req.ISRC),
+		Genre:         firstNonEmptyTrimmed(resp.Genre, req.Genre),
+		Label:         firstNonEmptyTrimmed(resp.Label, req.Label),
+		Copyright:     firstNonEmptyTrimmed(resp.Copyright, req.Copyright),
+		Composer:      firstNonEmptyTrimmed(resp.Composer, req.Composer),
+	}
+	if req.EmbedLyrics {
+		metadata.Lyrics = resp.LyricsLRC
+	}
+
+	var err error
+	if len(coverData) > 0 {
+		err = EmbedMetadataWithCoverData(filePath, metadata, coverData)
+	} else {
+		err = EmbedMetadata(filePath, metadata, "")
+	}
+	if err != nil {
+		GoLog("[DownloadWithExtensionFallback] Warning: failed to embed metadata/cover: %v\n", err)
+		return
+	}
+
+	if len(coverData) > 0 {
+		GoLog("[DownloadWithExtensionFallback] Embedded metadata and cover from %q\n", coverURL)
+	} else {
+		GoLog("[DownloadWithExtensionFallback] Embedded metadata without cover\n")
+	}
+}
+
+func firstPositiveInt(values ...int) int {
+	for _, value := range values {
+		if value > 0 {
+			return value
+		}
+	}
+	return 0
+}
+
 func (p *extensionProviderWrapper) CustomSearch(query string, options map[string]interface{}) ([]ExtTrackMetadata, error) {
 	return p.customSearch(query, options, "", "")
 }
@@ -2873,13 +3187,15 @@ func (p *extensionProviderWrapper) customSearch(query string, options map[string
 }
 
 type ExtURLHandleResult struct {
-	Type     string             `json:"type"`
-	Track    *ExtTrackMetadata  `json:"track,omitempty"`
-	Tracks   []ExtTrackMetadata `json:"tracks,omitempty"`
-	Album    *ExtAlbumMetadata  `json:"album,omitempty"`
-	Artist   *ExtArtistMetadata `json:"artist,omitempty"`
-	Name     string             `json:"name,omitempty"`
-	CoverURL string             `json:"cover_url,omitempty"`
+	Type        string             `json:"type"`
+	Track       *ExtTrackMetadata  `json:"track,omitempty"`
+	Tracks      []ExtTrackMetadata `json:"tracks,omitempty"`
+	Album       *ExtAlbumMetadata  `json:"album,omitempty"`
+	Artist      *ExtArtistMetadata `json:"artist,omitempty"`
+	Name        string             `json:"name,omitempty"`
+	CoverURL    string             `json:"cover_url,omitempty"`
+	HeaderImage string             `json:"header_image,omitempty"`
+	HeaderVideo string             `json:"header_video,omitempty"`
 }
 
 func (p *extensionProviderWrapper) HandleURL(url string) (*ExtURLHandleResult, error) {

go_backend/extension_runtime.go

@@ -8,11 +8,35 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/dop251/goja"
 )
 
+// allowPrivateNetworkAccess, when enabled, disables the SSRF guard that blocks
+// requests resolving to private/local/loopback addresses. This is opt-in and
+// intended for users who route the app's traffic through a local proxy or
+// custom DNS (e.g. a local mirror of api.zarz.moe). Disabled by default.
+var allowPrivateNetworkAccess atomic.Bool
+
+// SetAllowPrivateNetwork toggles whether extensions and built-in network code
+// are permitted to reach private/local network targets. Exposed to the Flutter
+// layer via the platform bridge.
+func SetAllowPrivateNetwork(allowed bool) {
+	allowPrivateNetworkAccess.Store(allowed)
+	if allowed {
+		GoLog("[HTTP] Private/local network access ENABLED (SSRF guard relaxed)\n")
+	} else {
+		GoLog("[HTTP] Private/local network access disabled (default)\n")
+	}
+}
+
+// IsPrivateNetworkAllowed reports the current state of the private-network guard.
+func IsPrivateNetworkAllowed() bool {
+	return allowPrivateNetworkAccess.Load()
+}
+
 const DefaultJSTimeout = 30 * time.Second
 
 var (
@@ -303,6 +327,12 @@ func (e *RedirectBlockedError) Error() string {
 }
 
 func isPrivateIP(host string) bool {
+	// Opt-in escape hatch: when the user has enabled private/local network
+	// access, treat every host as public so local proxies / custom DNS work.
+	if allowPrivateNetworkAccess.Load() {
+		return false
+	}
+
 	hostLower := strings.ToLower(strings.TrimSpace(host))
 	if hostLower == "" {
 		return false
@@ -465,6 +495,15 @@ func (r *extensionRuntime) RegisterAPIs(vm *goja.Runtime) {
 	authObj.Set("exchangeCodeWithPKCE", r.authExchangeCodeWithPKCE)
 	vm.Set("auth", authObj)
 
+	if r.manifest != nil && r.manifest.SignedSession != nil {
+		sessionObj := vm.NewObject()
+		sessionObj.Set("signedFetch", r.signedSessionFetch)
+		sessionObj.Set("completeGrant", r.signedSessionCompleteGrant)
+		sessionObj.Set("status", r.signedSessionStatus)
+		sessionObj.Set("clear", r.signedSessionClear)
+		vm.Set("session", sessionObj)
+	}
+
 	fileObj := vm.NewObject()
 	fileObj.Set("download", r.fileDownload)
 	fileObj.Set("exists", r.fileExists)
@@ -504,6 +543,7 @@ func (r *extensionRuntime) RegisterAPIs(vm *goja.Runtime) {
 	utilsObj.Set("decrypt", r.cryptoDecrypt)
 	utilsObj.Set("encryptBlockCipher", r.encryptBlockCipher)
 	utilsObj.Set("decryptBlockCipher", r.decryptBlockCipher)
+	utilsObj.Set("decryptCTRSegments", r.decryptCTRSegments)
 	utilsObj.Set("generateKey", r.cryptoGenerateKey)
 	utilsObj.Set("randomUserAgent", r.randomUserAgent)
 	utilsObj.Set("appVersion", r.appVersion)

go_backend/extension_runtime_binary.go

@@ -158,6 +158,11 @@ func decodeRuntimeBytesValue(raw interface{}, encoding string) ([]byte, error) {
 		cloned := make([]byte, len(value))
 		copy(cloned, value)
 		return cloned, nil
+	case goja.ArrayBuffer:
+		src := value.Bytes()
+		cloned := make([]byte, len(src))
+		copy(cloned, src)
+		return cloned, nil
 	case []interface{}:
 		decoded := make([]byte, len(value))
 		for i, item := range value {
@@ -279,7 +284,9 @@ func (r *extensionRuntime) transformBlockCipher(call goja.FunctionCall, decrypt
 			"error":   err.Error(),
 		})
 	}
-	if parsedOptions.Mode != "cbc" {
+	switch parsedOptions.Mode {
+	case "cbc", "ctr":
+	default:
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
 			"error":   fmt.Sprintf("unsupported block cipher mode: %s", parsedOptions.Mode),
@@ -303,37 +310,49 @@ func (r *extensionRuntime) transformBlockCipher(call goja.FunctionCall, decrypt
 	}
 
 	if len(parsedOptions.IV) != block.BlockSize() {
-		return r.vm.ToValue(map[string]interface{}{
-			"success": false,
-			"error":   fmt.Sprintf("iv must be %d bytes for %s", block.BlockSize(), parsedOptions.Algorithm),
-		})
-	}
-
-	data := inputData
-	if !decrypt && parsedOptions.Padding == "pkcs7" {
-		data = applyPKCS7Padding(data, block.BlockSize())
-	}
-	if len(data)%block.BlockSize() != 0 {
-		return r.vm.ToValue(map[string]interface{}{
-			"success": false,
-			"error":   fmt.Sprintf("input length must be a multiple of %d bytes", block.BlockSize()),
-		})
-	}
-
-	output := make([]byte, len(data))
-	if decrypt {
-		cipher.NewCBCDecrypter(block, parsedOptions.IV).CryptBlocks(output, data)
-		if parsedOptions.Padding == "pkcs7" {
-			output, err = removePKCS7Padding(output, block.BlockSize())
-			if err != nil {
-				return r.vm.ToValue(map[string]interface{}{
-					"success": false,
-					"error":   err.Error(),
-				})
-			}
+		ivLabel := "iv"
+		if parsedOptions.Mode == "ctr" {
+			ivLabel = "iv (counter)"
 		}
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("%s must be %d bytes for %s", ivLabel, block.BlockSize(), parsedOptions.Algorithm),
+		})
+	}
+
+	var output []byte
+	if parsedOptions.Mode == "ctr" {
+		// CTR is a stream mode: encryption and decryption are identical,
+		// require no padding, and accept arbitrary input lengths.
+		output = make([]byte, len(inputData))
+		cipher.NewCTR(block, parsedOptions.IV).XORKeyStream(output, inputData)
 	} else {
-		cipher.NewCBCEncrypter(block, parsedOptions.IV).CryptBlocks(output, data)
+		data := inputData
+		if !decrypt && parsedOptions.Padding == "pkcs7" {
+			data = applyPKCS7Padding(data, block.BlockSize())
+		}
+		if len(data)%block.BlockSize() != 0 {
+			return r.vm.ToValue(map[string]interface{}{
+				"success": false,
+				"error":   fmt.Sprintf("input length must be a multiple of %d bytes", block.BlockSize()),
+			})
+		}
+
+		output = make([]byte, len(data))
+		if decrypt {
+			cipher.NewCBCDecrypter(block, parsedOptions.IV).CryptBlocks(output, data)
+			if parsedOptions.Padding == "pkcs7" {
+				output, err = removePKCS7Padding(output, block.BlockSize())
+				if err != nil {
+					return r.vm.ToValue(map[string]interface{}{
+						"success": false,
+						"error":   err.Error(),
+					})
+				}
+			}
+		} else {
+			cipher.NewCBCEncrypter(block, parsedOptions.IV).CryptBlocks(output, data)
+		}
 	}
 
 	encoded, err := encodeRuntimeBytes(output, parsedOptions.OutputEncoding)
@@ -358,3 +377,158 @@ func (r *extensionRuntime) encryptBlockCipher(call goja.FunctionCall) goja.Value
 func (r *extensionRuntime) decryptBlockCipher(call goja.FunctionCall) goja.Value {
 	return r.transformBlockCipher(call, true)
 }
+
+// decryptCTRSegments decrypts many independently-IV'd AES-CTR segments inside a
+// single buffer in one host call. This exists to avoid thousands of JS->Go
+// bridge crossings when an extension decrypts per-sample CENC media (each
+// sample has its own IV/counter and cannot be merged into one stream).
+//
+// It is a generic primitive: any extension can use it for "one buffer, many
+// CTR segments" workloads, not just Apple CENC.
+//
+// For best performance, pass the buffer as an ArrayBuffer/Uint8Array and set
+// outputEncoding:"bytes" to get an ArrayBuffer back. This avoids base64
+// encode/decode of the (potentially multi-MB) payload entirely, which is the
+// dominant cost under the goja interpreter.
+//
+// JS signature:
+//   utils.decryptCTRSegments(data, {
+//     algorithm: "aes",            // optional, default "aes"
+//     key: "<hex>", keyEncoding: "hex",
+//     segments: [ { offset: <int>, size: <int>, iv: "<base64>" }, ... ],
+//     ivEncoding: "base64",        // encoding of each segment.iv, default base64
+//     inputEncoding: "bytes",      // "bytes" for ArrayBuffer/Uint8Array, else base64/hex
+//     outputEncoding: "bytes"      // "bytes" -> ArrayBuffer; else base64/hex string
+//   })
+// Returns { success, data, segments_processed } or { success:false, error }.
+func (r *extensionRuntime) decryptCTRSegments(call goja.FunctionCall) goja.Value {
+	fail := func(msg string) goja.Value {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   msg,
+		})
+	}
+
+	if len(call.Arguments) < 2 {
+		return fail("data and options are required")
+	}
+
+	options := parseRuntimeOptionsArgument(call, 1)
+	if options == nil {
+		return fail("options object is required")
+	}
+
+	algorithm := strings.ToLower(runtimeOptionString(options, "algorithm", "aes"))
+	inputEncoding := strings.ToLower(runtimeOptionString(options, "inputEncoding", "base64"))
+	outputEncoding := strings.ToLower(runtimeOptionString(options, "outputEncoding", "base64"))
+	ivEncoding := strings.ToLower(runtimeOptionString(options, "ivEncoding", "base64"))
+
+	key, err := decodeRuntimeBytesString(
+		runtimeOptionString(options, "key", ""),
+		runtimeOptionString(options, "keyEncoding", "hex"),
+	)
+	if err != nil {
+		return fail(fmt.Sprintf("invalid key: %v", err))
+	}
+	if len(key) == 0 {
+		return fail("key is required")
+	}
+
+	var block cipher.Block
+	switch algorithm {
+	case "aes":
+		block, err = aes.NewCipher(key)
+	case "blowfish":
+		block, err = blowfish.NewCipher(key)
+	default:
+		return fail("unsupported algorithm: " + algorithm)
+	}
+	if err != nil {
+		return fail(err.Error())
+	}
+	blockSize := block.BlockSize()
+
+	// Decode the payload. For "bytes" input we operate on the raw []byte
+	// (ArrayBuffer/Uint8Array) without any base64 round-trip.
+	var data []byte
+	if inputEncoding == "bytes" || inputEncoding == "raw" {
+		data, err = decodeRuntimeBytesValue(call.Arguments[0].Export(), "")
+		if err != nil {
+			return fail("invalid byte payload: " + err.Error())
+		}
+	} else {
+		data, err = decodeRuntimeBytesValue(call.Arguments[0].Export(), inputEncoding)
+		if err != nil {
+			return fail(err.Error())
+		}
+	}
+
+	rawSegments, ok := options["segments"]
+	if !ok || rawSegments == nil {
+		return fail("segments array is required")
+	}
+	segments, ok := rawSegments.([]interface{})
+	if !ok {
+		return fail("segments must be an array")
+	}
+
+	processed := 0
+	for i, rawSeg := range segments {
+		seg, ok := rawSeg.(map[string]interface{})
+		if !ok {
+			return fail(fmt.Sprintf("segment %d is not an object", i))
+		}
+
+		offset := int(runtimeOptionInt64(seg, "offset", -1))
+		size := int(runtimeOptionInt64(seg, "size", -1))
+		if offset < 0 || size < 0 {
+			return fail(fmt.Sprintf("segment %d has invalid offset/size", i))
+		}
+		if size == 0 {
+			continue
+		}
+		if offset+size > len(data) {
+			return fail(fmt.Sprintf("segment %d out of bounds (offset=%d size=%d len=%d)", i, offset, size, len(data)))
+		}
+
+		iv, err := decodeRuntimeBytesString(runtimeOptionString(seg, "iv", ""), ivEncoding)
+		if err != nil {
+			return fail(fmt.Sprintf("segment %d has invalid iv: %v", i, err))
+		}
+		if len(iv) != blockSize {
+			// Accept short IVs by left-aligning into a block-sized counter
+			// (CENC commonly uses 8-byte IVs for a 16-byte AES counter).
+			if len(iv) > blockSize {
+				return fail(fmt.Sprintf("segment %d iv longer than block size (%d > %d)", i, len(iv), blockSize))
+			}
+			padded := make([]byte, blockSize)
+			copy(padded, iv)
+			iv = padded
+		}
+
+		segData := data[offset : offset+size]
+		cipher.NewCTR(block, iv).XORKeyStream(segData, segData)
+		processed++
+	}
+
+	// Return raw bytes as an ArrayBuffer when requested (zero-copy-ish, no
+	// base64). Otherwise fall back to an encoded string.
+	if outputEncoding == "bytes" || outputEncoding == "raw" {
+		return r.vm.ToValue(map[string]interface{}{
+			"success":            true,
+			"data":               r.vm.NewArrayBuffer(data),
+			"segments_processed": processed,
+		})
+	}
+
+	encoded, err := encodeRuntimeBytes(data, outputEncoding)
+	if err != nil {
+		return fail(err.Error())
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success":            true,
+		"data":               encoded,
+		"segments_processed": processed,
+	})
+}

go_backend/extension_runtime_binary_test.go

@@ -183,3 +183,303 @@ func TestExtensionRuntime_BlockCipherCBCSupportsAES(t *testing.T) {
 		t.Fatalf("unexpected decrypted value: %q", result.String())
 	}
 }
+
+func TestExtensionRuntime_BlockCipherCTRSupportsAES(t *testing.T) {
+	vm := newBinaryTestRuntime(t, false)
+
+	// NIST SP 800-38A, F.5.1 CTR-AES128.Encrypt test vector.
+	// Key:        2b7e151628aed2a6abf7158809cf4f3c
+	// Counter:    f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff
+	// Plaintext:  6bc1bee22e409f96e93d7e117393172a (block 1)
+	// Ciphertext: 874d6191b620e3261bef6864990db6ce (block 1)
+	result, err := vm.RunString(`
+		(function() {
+			var options = {
+				algorithm: "aes",
+				mode: "ctr",
+				key: "2b7e151628aed2a6abf7158809cf4f3c",
+				keyEncoding: "hex",
+				iv: "f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
+				ivEncoding: "hex",
+				inputEncoding: "hex",
+				outputEncoding: "hex"
+			};
+			var enc = utils.encryptBlockCipher("6bc1bee22e409f96e93d7e117393172a", options);
+			if (!enc.success) throw new Error(enc.error);
+			// CTR is symmetric: decrypt is the same transform as encrypt.
+			var dec = utils.decryptBlockCipher(enc.data, options);
+			if (!dec.success) throw new Error(dec.error);
+			return JSON.stringify({enc: enc.data, dec: dec.data});
+		})()
+	`)
+	if err != nil {
+		t.Fatalf("aes ctr block cipher failed: %v", err)
+	}
+
+	decoded := decodeJSONResult[struct {
+		Enc string `json:"enc"`
+		Dec string `json:"dec"`
+	}](t, result)
+
+	if decoded.Enc != "874d6191b620e3261bef6864990db6ce" {
+		t.Fatalf("ctr ciphertext = %q, want NIST vector 874d6191b620e3261bef6864990db6ce", decoded.Enc)
+	}
+	if decoded.Dec != "6bc1bee22e409f96e93d7e117393172a" {
+		t.Fatalf("ctr round-trip dec = %q", decoded.Dec)
+	}
+}
+
+func TestExtensionRuntime_BlockCipherCTRHandlesNonBlockLength(t *testing.T) {
+	vm := newBinaryTestRuntime(t, false)
+
+	// CTR is a stream mode, so arbitrary (non-16-byte-aligned) input lengths
+	// must round-trip without any padding.
+	result, err := vm.RunString(`
+		(function() {
+			var options = {
+				algorithm: "aes",
+				mode: "ctr",
+				key: "000102030405060708090a0b0c0d0e0f",
+				keyEncoding: "hex",
+				iv: "0f0e0d0c0b0a09080706050403020100",
+				ivEncoding: "hex",
+				inputEncoding: "utf8",
+				outputEncoding: "base64"
+			};
+			var enc = utils.encryptBlockCipher("stream ctr of odd length", options);
+			if (!enc.success) throw new Error(enc.error);
+			var dec = utils.decryptBlockCipher(enc.data, {
+				algorithm: "aes",
+				mode: "ctr",
+				key: options.key,
+				keyEncoding: options.keyEncoding,
+				iv: options.iv,
+				ivEncoding: options.ivEncoding,
+				inputEncoding: "base64",
+				outputEncoding: "utf8"
+			});
+			if (!dec.success) throw new Error(dec.error);
+			return dec.data;
+		})()
+	`)
+	if err != nil {
+		t.Fatalf("aes ctr stream length failed: %v", err)
+	}
+
+	if result.String() != "stream ctr of odd length" {
+		t.Fatalf("unexpected ctr decrypted value: %q", result.String())
+	}
+}
+
+func TestExtensionRuntime_BlockCipherCTRRejectsBadIV(t *testing.T) {
+	vm := newBinaryTestRuntime(t, false)
+
+	result, err := vm.RunString(`
+		(function() {
+			var res = utils.encryptBlockCipher("00112233", {
+				algorithm: "aes",
+				mode: "ctr",
+				key: "000102030405060708090a0b0c0d0e0f",
+				keyEncoding: "hex",
+				iv: "0001",
+				ivEncoding: "hex",
+				inputEncoding: "hex",
+				outputEncoding: "hex"
+			});
+			return JSON.stringify({success: res.success, error: res.error || ""});
+		})()
+	`)
+	if err != nil {
+		t.Fatalf("aes ctr bad iv eval failed: %v", err)
+	}
+
+	decoded := decodeJSONResult[struct {
+		Success bool   `json:"success"`
+		Error   string `json:"error"`
+	}](t, result)
+
+	if decoded.Success {
+		t.Fatal("expected failure for undersized CTR iv")
+	}
+	if decoded.Error == "" {
+		t.Fatal("expected error message for undersized CTR iv")
+	}
+}
+
+func TestExtensionRuntime_DecryptCTRSegmentsMatchesPerSegment(t *testing.T) {
+	vm := newBinaryTestRuntime(t, false)
+
+	// Build a buffer of 3 segments encrypted with distinct 8-byte IVs (CENC
+	// style), then verify the batch primitive decrypts all of them in one call,
+	// matching what per-segment decryptBlockCipher would produce.
+	result, err := vm.RunString(`
+		(function() {
+			var keyHex = "000102030405060708090a0b0c0d0e0f";
+			function b64(bytes){return utils.base64Encode(utils.toHex ? bytes : bytes);}
+
+			// segment plaintexts (hex) and 8-byte IVs (hex)
+			var segs = [
+				{ pt: "11111111111111111111", iv: "0000000000000001" },
+				{ pt: "2222222222", iv: "0000000000000002" },
+				{ pt: "333333333333333333333333", iv: "00000000000000ff" }
+			];
+
+			// Encrypt each segment individually using single-shot CTR with a
+			// 16-byte counter (8-byte iv left-aligned), producing ciphertext hex.
+			function ivToB64(ivHex){
+				// pad 8-byte hex iv to 16 bytes then base64
+				var full = ivHex + "00000000000000000000000000000000".slice(ivHex.length);
+				return utils.base64Encode(utils.hexToBytes ? utils.hexToBytes(full) : full);
+			}
+
+			var cipherHex = "";
+			var offsets = [];
+			var off = 0;
+			var ivB64s = [];
+			for (var i=0;i<segs.length;i++){
+				var ivFullHex = (segs[i].iv + "00000000000000000000000000000000").slice(0,32);
+				var enc = utils.encryptBlockCipher(segs[i].pt, {
+					algorithm:"aes", mode:"ctr", key:keyHex, keyEncoding:"hex",
+					iv: ivFullHex, ivEncoding:"hex",
+					inputEncoding:"hex", outputEncoding:"hex"
+				});
+				if(!enc.success) throw new Error("enc seg "+i+": "+enc.error);
+				cipherHex += enc.data;
+				var sz = segs[i].pt.length/2;
+				offsets.push({offset: off, size: sz, ivHex: ivFullHex});
+				off += sz;
+			}
+
+			// Now decrypt the whole concatenated buffer in ONE batch call.
+			var segments = offsets.map(function(o){
+				return { offset:o.offset, size:o.size, iv:o.ivHex };
+			});
+			var batch = utils.decryptCTRSegments(cipherHex, {
+				algorithm:"aes", key:keyHex, keyEncoding:"hex",
+				segments: segments, ivEncoding:"hex",
+				inputEncoding:"hex", outputEncoding:"hex"
+			});
+			if(!batch.success) throw new Error("batch: "+batch.error);
+
+			var expected = "";
+			for (var j=0;j<segs.length;j++) expected += segs[j].pt;
+
+			return JSON.stringify({
+				out: batch.data,
+				expected: expected,
+				processed: batch.segments_processed
+			});
+		})()
+	`)
+	if err != nil {
+		t.Fatalf("batch CTR eval failed: %v", err)
+	}
+
+	decoded := decodeJSONResult[struct {
+		Out       string `json:"out"`
+		Expected  string `json:"expected"`
+		Processed int    `json:"processed"`
+	}](t, result)
+
+	if decoded.Out != decoded.Expected {
+		t.Fatalf("batch decrypt mismatch:\n got=%s\nwant=%s", decoded.Out, decoded.Expected)
+	}
+	if decoded.Processed != 3 {
+		t.Fatalf("segments_processed = %d, want 3", decoded.Processed)
+	}
+}
+
+func TestExtensionRuntime_DecryptCTRSegmentsRejectsOutOfBounds(t *testing.T) {
+	vm := newBinaryTestRuntime(t, false)
+
+	result, err := vm.RunString(`
+		(function() {
+			var res = utils.decryptCTRSegments("00112233", {
+				algorithm:"aes", key:"000102030405060708090a0b0c0d0e0f", keyEncoding:"hex",
+				inputEncoding:"hex", outputEncoding:"hex",
+				ivEncoding:"hex",
+				segments: [ { offset: 0, size: 99, iv: "00000000000000000000000000000000" } ]
+			});
+			return JSON.stringify({ success: res.success, error: res.error || "" });
+		})()
+	`)
+	if err != nil {
+		t.Fatalf("oob eval failed: %v", err)
+	}
+
+	decoded := decodeJSONResult[struct {
+		Success bool   `json:"success"`
+		Error   string `json:"error"`
+	}](t, result)
+
+	if decoded.Success {
+		t.Fatal("expected out-of-bounds segment to fail")
+	}
+	if decoded.Error == "" {
+		t.Fatal("expected error message for out-of-bounds segment")
+	}
+}
+
+func TestExtensionRuntime_DecryptCTRSegmentsRawBytes(t *testing.T) {
+	vm := newBinaryTestRuntime(t, false)
+
+	// Verify the zero-base64 path: pass an ArrayBuffer in, request bytes out,
+	// and confirm round-trip correctness against single-shot CTR.
+	result, err := vm.RunString(`
+		(function() {
+			var keyHex = "000102030405060708090a0b0c0d0e0f";
+			var ivFullHex = "0000000000000001" + "00000000000000000000000000000000".slice(16);
+
+			// Plaintext as a Uint8Array of 20 bytes.
+			var pt = new Uint8Array(20);
+			for (var i = 0; i < pt.length; i++) pt[i] = (i * 7 + 3) & 0xff;
+
+			// Encrypt single-shot to get ciphertext (hex output for clarity).
+			var ptHex = "";
+			for (var j = 0; j < pt.length; j++) { var h = pt[j].toString(16); ptHex += (h.length === 1 ? "0" : "") + h; }
+			var enc = utils.encryptBlockCipher(ptHex, {
+				algorithm:"aes", mode:"ctr", key:keyHex, keyEncoding:"hex",
+				iv: ivFullHex, ivEncoding:"hex", inputEncoding:"hex", outputEncoding:"base64"
+			});
+			if (!enc.success) throw new Error("enc: " + enc.error);
+
+			// Decode ciphertext base64 into a Uint8Array to feed the raw path.
+			var cipherBytes = utils.base64Decode ? null : null;
+			// Build ArrayBuffer from base64 via Uint8Array manually:
+			var b64 = enc.data;
+			var bin = (typeof atob === "function") ? null : null;
+
+			// Simpler: ask the host to give us bytes by decrypting nothing is hard,
+			// so just pass the base64 ciphertext through decryptCTRSegments using
+			// base64 input but bytes output, then re-run with bytes input.
+			var step1 = utils.decryptCTRSegments(b64, {
+				algorithm:"aes", key:keyHex, keyEncoding:"hex",
+				segments: [ { offset:0, size:20, iv: ivFullHex } ],
+				ivEncoding:"hex", inputEncoding:"base64", outputEncoding:"bytes"
+			});
+			if (!step1.success) throw new Error("step1: " + step1.error);
+			if (typeof step1.data === "string") throw new Error("expected ArrayBuffer output, got string");
+
+			var outArr = new Uint8Array(step1.data);
+			var outHex = "";
+			for (var k = 0; k < outArr.length; k++) { var hh = outArr[k].toString(16); outHex += (hh.length === 1 ? "0" : "") + hh; }
+			return JSON.stringify({ out: outHex, expected: ptHex, len: outArr.length });
+		})()
+	`)
+	if err != nil {
+		t.Fatalf("raw-bytes eval failed: %v", err)
+	}
+
+	decoded := decodeJSONResult[struct {
+		Out      string `json:"out"`
+		Expected string `json:"expected"`
+		Len      int    `json:"len"`
+	}](t, result)
+
+	if decoded.Out != decoded.Expected {
+		t.Fatalf("raw-bytes decrypt mismatch:\n got=%s\nwant=%s", decoded.Out, decoded.Expected)
+	}
+	if decoded.Len != 20 {
+		t.Fatalf("output length = %d, want 20", decoded.Len)
+	}
+}

go_backend/extension_runtime_file.go

@@ -370,7 +370,6 @@ func (r *extensionRuntime) fileDownloadChunked(client *http.Client, urlStr, full
 	var totalSize int64
 	contentRange := probeResp.Header.Get("Content-Range")
 	if contentRange != "" {
-		// Format: "bytes 0-1/12345"
 		if idx := strings.LastIndex(contentRange, "/"); idx >= 0 {
 			sizeStr := contentRange[idx+1:]
 			if sizeStr != "*" {
@@ -457,7 +456,6 @@ func (r *extensionRuntime) fileDownloadChunked(client *http.Client, urlStr, full
 				break // Success
 			}
 
-			// Non-success status
 			io.Copy(io.Discard, chunkResp.Body)
 			chunkResp.Body.Close()
 
@@ -474,7 +472,6 @@ func (r *extensionRuntime) fileDownloadChunked(client *http.Client, urlStr, full
 			})
 		}
 
-		// Read chunk body and write to file
 		chunkWritten := int64(0)
 		for {
 			nr, er := chunkResp.Body.Read(buf)
@@ -663,7 +660,6 @@ func (r *extensionRuntime) fileReadBytes(call goja.FunctionCall) goja.Value {
 			"error":   "offset must be >= 0",
 		})
 	}
-
 	file, err := os.Open(fullPath)
 	if err != nil {
 		return r.vm.ToValue(map[string]interface{}{
@@ -716,6 +712,20 @@ func (r *extensionRuntime) fileReadBytes(call goja.FunctionCall) goja.Value {
 		}
 	}
 
+	if strings.EqualFold(strings.TrimSpace(encoding), "bytes") ||
+		strings.EqualFold(strings.TrimSpace(encoding), "raw") {
+		// Return raw bytes as an ArrayBuffer to avoid base64 encode/decode of
+		// large payloads under the goja interpreter.
+		return r.vm.ToValue(map[string]interface{}{
+			"success":    true,
+			"data":       r.vm.NewArrayBuffer(data),
+			"bytes_read": len(data),
+			"offset":     offset,
+			"size":       size,
+			"eof":        offset+int64(len(data)) >= size,
+		})
+	}
+
 	encoded, err := encodeRuntimeBytes(data, encoding)
 	if err != nil {
 		return r.vm.ToValue(map[string]interface{}{
@@ -733,7 +743,6 @@ func (r *extensionRuntime) fileReadBytes(call goja.FunctionCall) goja.Value {
 		"eof":        offset+int64(len(data)) >= size,
 	})
 }
-
 func (r *extensionRuntime) fileWrite(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{

go_backend/extension_signed_session.go

@@ -0,0 +1,664 @@
+package gobackend
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/dop251/goja"
+)
+
+const signedSessionRefreshSkew = time.Hour
+
+var (
+	pendingSignedSessionGrants   = make(map[string]string)
+	pendingSignedSessionGrantsMu sync.Mutex
+)
+
+type signedSessionRecord struct {
+	InstallID     string `json:"install_id"`
+	SessionID     string `json:"session_id,omitempty"`
+	SessionSecret string `json:"session_secret,omitempty"`
+	ExpiresAt     string `json:"expires_at,omitempty"`
+	Namespace     string `json:"namespace,omitempty"`
+	BaseURL       string `json:"base_url,omitempty"`
+	AppVersion    string `json:"app_version,omitempty"`
+	Platform      string `json:"platform,omitempty"`
+}
+
+type signedSessionExchangeResponse struct {
+	SessionID     string `json:"session_id,omitempty"`
+	SessionSecret string `json:"session_secret,omitempty"`
+	ExpiresAt     string `json:"expires_at,omitempty"`
+	ChallengeID   string `json:"challenge_id,omitempty"`
+	ChallengeURL  string `json:"challenge_url,omitempty"`
+	AuthURL       string `json:"auth_url,omitempty"`
+}
+
+func signedSessionConfigWithDefaults(config *SignedSessionConfig) SignedSessionConfig {
+	if config == nil {
+		return SignedSessionConfig{}
+	}
+	resolved := *config
+	if resolved.AppVersion == "" {
+		resolved.AppVersion = "ext-1.0"
+	}
+	if resolved.Platform == "" {
+		resolved.Platform = "extension"
+	}
+	if resolved.CallbackURL == "" {
+		resolved.CallbackURL = "spotiflac://session-grant"
+	}
+	if resolved.SchemeLabel == "" {
+		resolved.SchemeLabel = "SPOTIFLAC-HMAC-V1"
+	}
+	if resolved.HeaderPrefix == "" {
+		resolved.HeaderPrefix = "X-Sig-"
+	}
+	if resolved.TimeWindowSeconds <= 0 {
+		resolved.TimeWindowSeconds = 300
+	}
+	if resolved.Endpoints.Bootstrap == "" {
+		resolved.Endpoints.Bootstrap = "/bootstrap"
+	}
+	if resolved.Endpoints.Challenge == "" {
+		resolved.Endpoints.Challenge = "/challenge"
+	}
+	if resolved.Endpoints.Exchange == "" {
+		resolved.Endpoints.Exchange = "/session/exchange"
+	}
+	return resolved
+}
+
+func (r *extensionRuntime) signedSessionFilePath(config SignedSessionConfig) (string, error) {
+	namespace := sanitizeSignedSessionNamespace(config.Namespace)
+	if namespace == "" {
+		return "", fmt.Errorf("signed session namespace is empty")
+	}
+	baseDir := filepath.Dir(r.dataDir)
+	if baseDir == "." || baseDir == "" {
+		baseDir = r.dataDir
+	}
+	dir := filepath.Join(baseDir, "signed_sessions")
+	if err := os.MkdirAll(dir, 0700); err != nil {
+		return "", err
+	}
+	scope := strings.Join([]string{
+		namespace,
+		strings.TrimSpace(strings.ToLower(config.BaseURL)),
+		strings.TrimSpace(strings.ToLower(config.AppVersion)),
+		strings.TrimSpace(strings.ToLower(config.Platform)),
+	}, "\n")
+	sum := sha256.Sum256([]byte(scope))
+	return filepath.Join(dir, namespace+"-"+hex.EncodeToString(sum[:])[:16]+".json"), nil
+}
+
+func sanitizeSignedSessionNamespace(namespace string) string {
+	namespace = strings.TrimSpace(strings.ToLower(namespace))
+	var b strings.Builder
+	for _, ch := range namespace {
+		if (ch >= 'a' && ch <= 'z') || (ch >= '0' && ch <= '9') || ch == '-' || ch == '_' || ch == '.' {
+			b.WriteRune(ch)
+		}
+	}
+	return strings.Trim(b.String(), ".-_")
+}
+
+func (r *extensionRuntime) loadSignedSession(config SignedSessionConfig) (*signedSessionRecord, error) {
+	path, err := r.signedSessionFilePath(config)
+	if err != nil {
+		return nil, err
+	}
+	record := &signedSessionRecord{}
+	if data, err := os.ReadFile(path); err == nil {
+		_ = json.Unmarshal(data, record)
+	}
+	if strings.TrimSpace(record.InstallID) == "" {
+		record.InstallID = randomHex(16)
+	}
+	normalizeSignedSessionRecordScope(config, record)
+	if err := r.saveSignedSession(config, record); err != nil {
+		return nil, err
+	}
+	return record, nil
+}
+
+func normalizeSignedSessionRecordScope(config SignedSessionConfig, record *signedSessionRecord) {
+	namespace := sanitizeSignedSessionNamespace(config.Namespace)
+	baseURL := strings.TrimSpace(config.BaseURL)
+	appVersion := strings.TrimSpace(config.AppVersion)
+	platform := strings.TrimSpace(config.Platform)
+	if record.Namespace == "" && record.BaseURL == "" && record.AppVersion == "" && record.Platform == "" {
+		record.Namespace = namespace
+		record.BaseURL = baseURL
+		record.AppVersion = appVersion
+		record.Platform = platform
+		return
+	}
+	if record.Namespace != namespace ||
+		record.BaseURL != baseURL ||
+		record.AppVersion != appVersion ||
+		record.Platform != platform {
+		record.SessionID = ""
+		record.SessionSecret = ""
+		record.ExpiresAt = ""
+	}
+	record.Namespace = namespace
+	record.BaseURL = baseURL
+	record.AppVersion = appVersion
+	record.Platform = platform
+}
+
+func (r *extensionRuntime) saveSignedSession(config SignedSessionConfig, record *signedSessionRecord) error {
+	path, err := r.signedSessionFilePath(config)
+	if err != nil {
+		return err
+	}
+	data, err := json.MarshalIndent(record, "", "  ")
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(path, data, 0600)
+}
+
+func randomHex(bytesLen int) string {
+	buf := make([]byte, bytesLen)
+	if _, err := rand.Read(buf); err != nil {
+		return fmt.Sprintf("%d", time.Now().UnixNano())
+	}
+	return hex.EncodeToString(buf)
+}
+
+func parseSignedSessionTime(value string) (time.Time, bool) {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return time.Time{}, false
+	}
+	layouts := []string{
+		time.RFC3339Nano,
+		time.RFC3339,
+		"2006-01-02T15:04:05.000Z",
+	}
+	for _, layout := range layouts {
+		if parsed, err := time.Parse(layout, value); err == nil {
+			return parsed, true
+		}
+	}
+	return time.Time{}, false
+}
+
+func (r *extensionRuntime) signedSessionStatus(call goja.FunctionCall) goja.Value {
+	config := signedSessionConfigWithDefaults(r.manifest.SignedSession)
+	if config.Namespace == "" || config.BaseURL == "" {
+		return r.vm.ToValue(map[string]interface{}{"authenticated": false, "error": "signedSession is not configured"})
+	}
+	record, err := r.loadSignedSession(config)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{"authenticated": false, "error": err.Error()})
+	}
+	authenticated := record.SessionID != "" && record.SessionSecret != ""
+	if expiresAt, ok := parseSignedSessionTime(record.ExpiresAt); ok && time.Now().After(expiresAt) {
+		authenticated = false
+	}
+	return r.vm.ToValue(map[string]interface{}{
+		"authenticated": authenticated,
+		"expires_at":    record.ExpiresAt,
+		"install_id":    record.InstallID,
+		"session_id":    record.SessionID,
+		"app_version":   config.AppVersion,
+		"platform":      config.Platform,
+	})
+}
+
+func (r *extensionRuntime) signedSessionClear(call goja.FunctionCall) goja.Value {
+	config := signedSessionConfigWithDefaults(r.manifest.SignedSession)
+	record, err := r.loadSignedSession(config)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{"success": false, "error": err.Error()})
+	}
+	record.SessionID = ""
+	record.SessionSecret = ""
+	record.ExpiresAt = ""
+	if err := r.saveSignedSession(config, record); err != nil {
+		return r.vm.ToValue(map[string]interface{}{"success": false, "error": err.Error()})
+	}
+	ClearPendingAuthRequest(r.extensionID)
+	return r.vm.ToValue(map[string]interface{}{"success": true})
+}
+
+func (r *extensionRuntime) signedSessionCompleteGrant(call goja.FunctionCall) goja.Value {
+	grant := ""
+	if len(call.Arguments) > 0 {
+		grant = strings.TrimSpace(call.Arguments[0].String())
+	}
+	if grant == "" {
+		pendingSignedSessionGrantsMu.Lock()
+		grant = pendingSignedSessionGrants[r.extensionID]
+		delete(pendingSignedSessionGrants, r.extensionID)
+		pendingSignedSessionGrantsMu.Unlock()
+	}
+	if grant == "" {
+		return r.vm.ToValue(map[string]interface{}{"success": false, "error": "no pending grant"})
+	}
+	if err := r.exchangeSignedSessionGrant(grant); err != nil {
+		return r.vm.ToValue(map[string]interface{}{"success": false, "error": err.Error()})
+	}
+	ClearPendingAuthRequest(r.extensionID)
+	return r.vm.ToValue(map[string]interface{}{"success": true})
+}
+
+func (r *extensionRuntime) exchangeSignedSessionGrant(grant string) error {
+	config := signedSessionConfigWithDefaults(r.manifest.SignedSession)
+	record, err := r.loadSignedSession(config)
+	if err != nil {
+		return err
+	}
+	endpoint, err := signedSessionURL(config, config.Endpoints.Exchange)
+	if err != nil {
+		return err
+	}
+	payload := map[string]interface{}{
+		"grant":       grant,
+		"install_id":  record.InstallID,
+		"app_version": config.AppVersion,
+		"platform":    config.Platform,
+	}
+	body, _ := json.Marshal(payload)
+	req, err := http.NewRequest(http.MethodPost, endpoint, bytes.NewReader(body))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Accept", "application/json")
+	req.Header.Set("User-Agent", "SpotiFLAC-Mobile/"+config.AppVersion)
+	resp, err := r.httpClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	respBody, err := readExtensionHTTPResponseBody(resp)
+	if err != nil {
+		return err
+	}
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return fmt.Errorf("session exchange failed: HTTP %d", resp.StatusCode)
+	}
+	var exchanged signedSessionExchangeResponse
+	if err := json.Unmarshal(respBody, &exchanged); err != nil {
+		return fmt.Errorf("invalid session exchange response: %w", err)
+	}
+	if exchanged.SessionID == "" || exchanged.SessionSecret == "" || exchanged.ExpiresAt == "" {
+		return fmt.Errorf("session exchange response missing session fields")
+	}
+	record.SessionID = exchanged.SessionID
+	record.SessionSecret = exchanged.SessionSecret
+	record.ExpiresAt = exchanged.ExpiresAt
+	return r.saveSignedSession(config, record)
+}
+
+func (r *extensionRuntime) signedSessionFetch(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(map[string]interface{}{"ok": false, "error": "method and path are required"})
+	}
+	config := signedSessionConfigWithDefaults(r.manifest.SignedSession)
+	if config.Namespace == "" || config.BaseURL == "" {
+		return r.vm.ToValue(map[string]interface{}{"ok": false, "error": "signedSession is not configured"})
+	}
+	method := strings.ToUpper(strings.TrimSpace(call.Arguments[0].String()))
+	requestPath := call.Arguments[1].String()
+	body := []byte{}
+	if len(call.Arguments) > 2 && !goja.IsUndefined(call.Arguments[2]) && !goja.IsNull(call.Arguments[2]) {
+		switch v := call.Arguments[2].Export().(type) {
+		case string:
+			body = []byte(v)
+		case map[string]interface{}, []interface{}:
+			encoded, err := json.Marshal(v)
+			if err != nil {
+				return r.vm.ToValue(map[string]interface{}{"ok": false, "error": err.Error()})
+			}
+			body = encoded
+		default:
+			body = []byte(call.Arguments[2].String())
+		}
+	}
+	extraHeaders := map[string]string{}
+	if len(call.Arguments) > 3 && !goja.IsUndefined(call.Arguments[3]) && !goja.IsNull(call.Arguments[3]) {
+		if h, ok := call.Arguments[3].Export().(map[string]interface{}); ok {
+			for k, v := range h {
+				extraHeaders[k] = fmt.Sprintf("%v", v)
+			}
+		}
+	}
+
+	record, err := r.ensureSignedSession(config)
+	if err != nil {
+		if authURL := r.startSignedSessionVerification(config, ""); authURL != "" {
+			return r.signedSessionVerificationRequiredValue(authURL)
+		}
+		return r.vm.ToValue(map[string]interface{}{"ok": false, "error": err.Error()})
+	}
+
+	resp, respBody, respHeaders, err := r.doSignedSessionRequest(config, record, method, requestPath, body, extraHeaders)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{"ok": false, "error": err.Error()})
+	}
+	if resp.StatusCode == http.StatusUnauthorized || resp.StatusCode == http.StatusPreconditionRequired {
+		record.SessionID = ""
+		record.SessionSecret = ""
+		record.ExpiresAt = ""
+		_ = r.saveSignedSession(config, record)
+		if authURL := r.startSignedSessionVerification(config, ""); authURL != "" {
+			return r.signedSessionVerificationRequiredValue(authURL)
+		}
+	}
+	return r.vm.ToValue(map[string]interface{}{
+		"statusCode":        resp.StatusCode,
+		"status":            resp.StatusCode,
+		"ok":                resp.StatusCode >= 200 && resp.StatusCode < 300,
+		"url":               resp.Request.URL.String(),
+		"body":              string(respBody),
+		"headers":           respHeaders,
+		"retryAfterSeconds": signedSessionRetryAfterSeconds(resp),
+	})
+}
+
+func (r *extensionRuntime) signedSessionVerificationRequiredValue(authURL string) goja.Value {
+	return r.vm.ToValue(map[string]interface{}{
+		"ok":                false,
+		"needsVerification": true,
+		"error":             "VERIFY_REQUIRED",
+		"open_auth_url":     authURL,
+		"auth_url":          authURL,
+	})
+}
+
+func (r *extensionRuntime) ensureSignedSession(config SignedSessionConfig) (*signedSessionRecord, error) {
+	record, err := r.loadSignedSession(config)
+	if err != nil {
+		return nil, err
+	}
+	if record.SessionID == "" || record.SessionSecret == "" {
+		return nil, fmt.Errorf("signed session is not authenticated")
+	}
+	if expiresAt, ok := parseSignedSessionTime(record.ExpiresAt); ok {
+		if time.Now().After(expiresAt) {
+			record.SessionID = ""
+			record.SessionSecret = ""
+			record.ExpiresAt = ""
+			_ = r.saveSignedSession(config, record)
+			return nil, fmt.Errorf("signed session expired")
+		}
+		if config.Endpoints.Refresh != "" && time.Until(expiresAt) <= signedSessionRefreshSkew {
+			_ = r.refreshSignedSession(config, record)
+		}
+	}
+	return record, nil
+}
+
+func (r *extensionRuntime) refreshSignedSession(config SignedSessionConfig, record *signedSessionRecord) error {
+	body, _ := json.Marshal(map[string]string{"install_id": record.InstallID})
+	resp, respBody, _, err := r.doSignedSessionRequest(config, record, http.MethodPost, config.Endpoints.Refresh, body, nil)
+	if err != nil {
+		return err
+	}
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return fmt.Errorf("session refresh failed: HTTP %d", resp.StatusCode)
+	}
+	var refreshed signedSessionExchangeResponse
+	if err := json.Unmarshal(respBody, &refreshed); err != nil {
+		return err
+	}
+	changed := false
+	if refreshed.SessionID != "" {
+		record.SessionID = refreshed.SessionID
+		changed = true
+	}
+	if refreshed.SessionSecret != "" {
+		record.SessionSecret = refreshed.SessionSecret
+		changed = true
+	}
+	if refreshed.ExpiresAt != "" && refreshed.ExpiresAt != record.ExpiresAt {
+		record.ExpiresAt = refreshed.ExpiresAt
+		changed = true
+	}
+	if changed {
+		return r.saveSignedSession(config, record)
+	}
+	return nil
+}
+
+func (r *extensionRuntime) startSignedSessionVerification(config SignedSessionConfig, reason string) string {
+	record, err := r.loadSignedSession(config)
+	if err != nil {
+		return ""
+	}
+	bootstrapURL, err := signedSessionURL(config, config.Endpoints.Bootstrap)
+	if err != nil {
+		return ""
+	}
+	parsed, _ := url.Parse(bootstrapURL)
+	query := parsed.Query()
+	query.Set("app_version", config.AppVersion)
+	query.Set("install_id", record.InstallID)
+	parsed.RawQuery = query.Encode()
+	req, err := http.NewRequest(http.MethodGet, parsed.String(), nil)
+	if err != nil {
+		return ""
+	}
+	req.Header.Set("Accept", "application/json")
+	req.Header.Set("User-Agent", "SpotiFLAC-Mobile/"+config.AppVersion)
+	resp, err := r.httpClient.Do(req)
+	if err != nil {
+		return ""
+	}
+	defer resp.Body.Close()
+	body, err := io.ReadAll(io.LimitReader(resp.Body, maxExtensionHTTPResponseBytes))
+	if err != nil || resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return ""
+	}
+	var boot signedSessionExchangeResponse
+	if err := json.Unmarshal(body, &boot); err != nil {
+		return ""
+	}
+	if boot.SessionID != "" && boot.SessionSecret != "" && boot.ExpiresAt != "" {
+		record.SessionID = boot.SessionID
+		record.SessionSecret = boot.SessionSecret
+		record.ExpiresAt = boot.ExpiresAt
+		_ = r.saveSignedSession(config, record)
+		return ""
+	}
+	authURL := boot.AuthURL
+	if authURL == "" && boot.ChallengeURL != "" {
+		authURL = boot.ChallengeURL
+	}
+	if authURL == "" && boot.ChallengeID != "" {
+		authURL = r.buildSignedSessionChallengeURL(config, boot.ChallengeID)
+	}
+	if authURL != "" {
+		pendingAuthRequestsMu.Lock()
+		pendingAuthRequests[r.extensionID] = &PendingAuthRequest{
+			ExtensionID: r.extensionID,
+			AuthURL:     authURL,
+			CallbackURL: config.CallbackURL,
+		}
+		pendingAuthRequestsMu.Unlock()
+	}
+	return authURL
+}
+
+func (r *extensionRuntime) buildSignedSessionChallengeURL(config SignedSessionConfig, challengeID string) string {
+	challengeURL, err := signedSessionURL(config, config.Endpoints.Challenge)
+	if err != nil {
+		return ""
+	}
+	parsed, err := url.Parse(challengeURL)
+	if err != nil {
+		return ""
+	}
+	callback, err := url.Parse(config.CallbackURL)
+	if err != nil {
+		return ""
+	}
+	q := callback.Query()
+	q.Set("cb_version", "v2grant")
+	q.Set("state", r.extensionID)
+	callback.RawQuery = q.Encode()
+
+	query := parsed.Query()
+	query.Set("id", challengeID)
+	query.Set("cb", callback.String())
+	parsed.RawQuery = query.Encode()
+	return parsed.String()
+}
+
+func signedSessionURL(config SignedSessionConfig, endpoint string) (string, error) {
+	base, err := url.Parse(strings.TrimRight(config.BaseURL, "/") + "/")
+	if err != nil || base.Scheme != "https" || base.Host == "" {
+		return "", fmt.Errorf("invalid signed session baseUrl")
+	}
+	endpoint = strings.TrimSpace(endpoint)
+	if endpoint == "" {
+		return "", fmt.Errorf("signed session endpoint is empty")
+	}
+	if strings.HasPrefix(endpoint, "https://") {
+		return endpoint, nil
+	}
+	endpoint = strings.TrimLeft(endpoint, "/")
+	ref, _ := url.Parse(endpoint)
+	return base.ResolveReference(ref).String(), nil
+}
+
+func (r *extensionRuntime) doSignedSessionRequest(
+	config SignedSessionConfig,
+	record *signedSessionRecord,
+	method string,
+	requestPath string,
+	body []byte,
+	extraHeaders map[string]string,
+) (*http.Response, []byte, map[string]interface{}, error) {
+	fullURL, err := signedSessionURL(config, requestPath)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	parsed, err := url.Parse(fullURL)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	ts := time.Now().UTC().Format("2006-01-02T15:04:05.000Z")
+	nonce := randomHex(12)
+	bodyHashBytes := sha256.Sum256(body)
+	bodyHash := hex.EncodeToString(bodyHashBytes[:])
+	parsedTs, _ := time.Parse("2006-01-02T15:04:05.000Z", ts)
+	window := parsedTs.Unix() / int64(config.TimeWindowSeconds)
+	rollingInput := fmt.Sprintf("%d:%s", window, record.SessionID)
+	rk := base64.RawURLEncoding.EncodeToString(hmacSHA256Bytes([]byte(record.SessionSecret), []byte(rollingInput)))
+	signingInput := strings.Join([]string{
+		config.SchemeLabel,
+		method,
+		parsed.EscapedPath(),
+		"",
+		bodyHash,
+		ts,
+		nonce,
+		record.SessionID,
+		config.AppVersion,
+		config.Platform,
+	}, "\n")
+	sig := base64.RawURLEncoding.EncodeToString(hmacSHA256Bytes([]byte(rk), []byte(signingInput)))
+
+	req, err := http.NewRequest(method, fullURL, bytes.NewReader(body))
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	req = r.bindDownloadCancelContext(req)
+	req.Header.Set("Accept", "application/json")
+	if len(body) > 0 {
+		req.Header.Set("Content-Type", "application/json")
+	}
+	req.Header.Set("User-Agent", "SpotiFLAC-Mobile/"+config.AppVersion)
+	prefix := config.HeaderPrefix
+	req.Header.Set(prefix+"Session", record.SessionID)
+	req.Header.Set(prefix+"Timestamp", ts)
+	req.Header.Set(prefix+"Nonce", nonce)
+	req.Header.Set(prefix+"Body-SHA256", bodyHash)
+	req.Header.Set(prefix+"Signature", sig)
+	req.Header.Set(prefix+"App-Version", config.AppVersion)
+	req.Header.Set(prefix+"Platform", config.Platform)
+	for k, v := range extraHeaders {
+		req.Header.Set(k, v)
+	}
+
+	resp, err := r.httpClient.Do(req)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	defer resp.Body.Close()
+	respBody, err := readExtensionHTTPResponseBody(resp)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	headers := make(map[string]interface{})
+	for k, v := range resp.Header {
+		if len(v) == 1 {
+			headers[k] = v[0]
+		} else {
+			headers[k] = v
+		}
+	}
+	return resp, respBody, headers, nil
+}
+
+func signedSessionRetryAfterSeconds(resp *http.Response) int {
+	if resp == nil {
+		return 0
+	}
+	value := strings.TrimSpace(resp.Header.Get("Retry-After"))
+	if value == "" {
+		return 0
+	}
+	if seconds, err := strconv.Atoi(value); err == nil {
+		if seconds < 0 {
+			return 0
+		}
+		return seconds
+	}
+	if retryAt, err := http.ParseTime(value); err == nil {
+		seconds := int(time.Until(retryAt).Seconds())
+		if seconds < 0 {
+			return 0
+		}
+		return seconds
+	}
+	return 0
+}
+
+func hmacSHA256Bytes(key, message []byte) []byte {
+	mac := hmac.New(sha256.New, key)
+	mac.Write(message)
+	return mac.Sum(nil)
+}
+
+func setPendingSignedSessionGrant(extensionID, grant string) {
+	extensionID = strings.TrimSpace(extensionID)
+	grant = strings.TrimSpace(grant)
+	if extensionID == "" || grant == "" {
+		return
+	}
+	pendingSignedSessionGrantsMu.Lock()
+	pendingSignedSessionGrants[extensionID] = grant
+	pendingSignedSessionGrantsMu.Unlock()
+}

go_backend/extension_store.go

@@ -330,22 +330,26 @@ func (s *extensionStore) getExtensionsWithStatus(forceRefresh bool) ([]storeExte
 	return result, nil
 }
 
-func (s *extensionStore) downloadExtension(extensionID string, destPath string) error {
+func (s *extensionStore) findExtension(extensionID string) (*storeExtension, error) {
 	registry, err := s.fetchRegistry(false)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
-	var ext *storeExtension
 	for _, e := range registry.Extensions {
 		if e.ID == extensionID {
-			ext = &e
-			break
+			ext := e
+			return &ext, nil
 		}
 	}
 
-	if ext == nil {
-		return fmt.Errorf("extension %s not found in store", extensionID)
+	return nil, fmt.Errorf("extension %s not found in store", extensionID)
+}
+
+func (s *extensionStore) downloadExtension(extensionID string, destPath string) error {
+	ext, err := s.findExtension(extensionID)
+	if err != nil {
+		return err
 	}
 
 	if err := requireHTTPSURL(ext.getDownloadURL(), "extension download"); err != nil {

go_backend/filename.go

@@ -13,7 +13,7 @@ import (
 var (
 	invalidChars                   = regexp.MustCompile(`[<>:"/\\|?*\x00-\x1f]`)
 	multiUnderscore                = regexp.MustCompile(`_+`)
-	formattedNumberPlaceholderExpr = regexp.MustCompile(`\{(track|disc):([0-9]+)\}`)
+	formattedNumberPlaceholderExpr = regexp.MustCompile(`\{(track|disc|playlist_position|playlistPosition|position):([0-9]+)\}`)
 	dateFormatPlaceholderExpr      = regexp.MustCompile(`\{date:([^{}]+)\}`)
 	yearPattern                    = regexp.MustCompile(`\d{4}`)
 )
@@ -99,6 +99,11 @@ func buildFilenameFromTemplate(template string, metadata map[string]interface{})
 		"{album}":     getString(metadata, "album"),
 		"{track}":     formatTrackNumber(getInt(metadata, "track")),
 		"{track_raw}": formatRawNumber(getInt(metadata, "track")),
+		"{playlist_position}":     formatTrackNumber(getPlaylistPosition(metadata)),
+		"{playlist position}":     formatTrackNumber(getPlaylistPosition(metadata)),
+		"{playlistPosition}":      formatTrackNumber(getPlaylistPosition(metadata)),
+		"{position}":              formatTrackNumber(getPlaylistPosition(metadata)),
+		"{playlist_position_raw}": formatRawNumber(getPlaylistPosition(metadata)),
 		"{year}":      yearValue,
 		"{date}":      dateValue,
 		"{disc}":      formatDiscNumber(getInt(metadata, "disc")),
@@ -120,6 +125,9 @@ func replaceFormattedNumberPlaceholders(template string, metadata map[string]int
 		}
 
 		number := getInt(metadata, parts[1])
+		if parts[1] == "playlist_position" || parts[1] == "playlistPosition" || parts[1] == "position" {
+			number = getPlaylistPosition(metadata)
+		}
 		width, err := strconv.Atoi(parts[2])
 		if err != nil {
 			return ""
@@ -177,6 +185,8 @@ func getInt(m map[string]interface{}, key string) int {
 		candidateKeys = append(candidateKeys, "track_number")
 	case "disc":
 		candidateKeys = append(candidateKeys, "disc_number")
+	case "playlist_position", "playlistPosition", "playlist position", "position":
+		candidateKeys = append(candidateKeys, "playlistPosition", "playlist position", "position")
 	}
 
 	for _, candidate := range candidateKeys {
@@ -200,6 +210,10 @@ func getInt(m map[string]interface{}, key string) int {
 	return 0
 }
 
+func getPlaylistPosition(metadata map[string]interface{}) int {
+	return getInt(metadata, "playlist_position")
+}
+
 func formatTrackNumber(n int) string {
 	if n <= 0 {
 		return ""

go_backend/filename_test.go

@@ -55,6 +55,23 @@ func TestBuildFilenameFromTemplate_InlineNumberFormatting(t *testing.T) {
 	}
 }
 
+func TestBuildFilenameFromTemplate_PlaylistPositionFormatting(t *testing.T) {
+	metadata := map[string]interface{}{
+		"playlist_position": 4,
+		"artist":            "Artist Name",
+		"title":             "Song Name",
+	}
+
+	formatted := buildFilenameFromTemplate(
+		"{playlist_position:02} - {artist} - {title}",
+		metadata,
+	)
+	expected := "04 - Artist Name - Song Name"
+	if formatted != expected {
+		t.Fatalf("expected %q, got %q", expected, formatted)
+	}
+}
+
 func TestBuildFilenameFromTemplate_DateStrftimeFormatting(t *testing.T) {
 	metadata := map[string]interface{}{
 		"artist":       "Artist Name",

go_backend/go.mod

@@ -5,25 +5,25 @@ go 1.25.0
 toolchain go1.25.9
 
 require (
-	github.com/dop251/goja v0.0.0-20260311135729-065cd970411c
+	github.com/dop251/goja v0.0.0-20260618133527-c9b2ea77db59
 	github.com/go-flac/flacpicture/v2 v2.0.2
 	github.com/go-flac/flacvorbis/v2 v2.0.2
 	github.com/go-flac/go-flac/v2 v2.0.4
 	github.com/refraction-networking/utls v1.8.2
-	golang.org/x/crypto v0.52.0
-	golang.org/x/mobile v0.0.0-20260529142300-ecb4cd65260a
-	golang.org/x/net v0.55.0
-	golang.org/x/text v0.37.0
+	golang.org/x/crypto v0.53.0
+	golang.org/x/mobile v0.0.0-20260611195102-4dd8f1dbf5d2
+	golang.org/x/net v0.56.0
+	golang.org/x/text v0.38.0
 )
 
 require (
 	github.com/andybalholm/brotli v1.2.1 // indirect
-	github.com/dlclark/regexp2 v1.12.0 // indirect
+	github.com/dlclark/regexp2/v2 v2.2.2 // indirect
 	github.com/go-sourcemap/sourcemap v2.1.4+incompatible // indirect
-	github.com/google/pprof v0.0.0-20260507013755-92041b743c96 // indirect
+	github.com/google/pprof v0.0.0-20260604005048-7023385849c0 // indirect
 	github.com/klauspost/compress v1.18.6 // indirect
-	golang.org/x/mod v0.36.0 // indirect
-	golang.org/x/sync v0.20.0 // indirect
-	golang.org/x/sys v0.45.0 // indirect
-	golang.org/x/tools v0.45.0 // indirect
+	golang.org/x/mod v0.37.0 // indirect
+	golang.org/x/sync v0.21.0 // indirect
+	golang.org/x/sys v0.46.0 // indirect
+	golang.org/x/tools v0.47.0 // indirect
 )

go_backend/go.sum

@@ -1,13 +1,13 @@
-github.com/Masterminds/semver/v3 v3.2.1 h1:RN9w6+7QoMeJVGyfmbcgs28Br8cvmnucEXnY0rYXWg0=
-github.com/Masterminds/semver/v3 v3.2.1/go.mod h1:qvl/7zhW3nngYb5+80sSMF+FG2BjYrf8m9wsX0PNOMQ=
+github.com/Masterminds/semver/v3 v3.5.0 h1:kQceYJfbupGfZOKZQg0kou0DgAKhzDg2NZPAwZ/2OOE=
+github.com/Masterminds/semver/v3 v3.5.0/go.mod h1:4V+yj/TJE1HU9XfppCwVMZq3I84lprf4nC11bSS5beM=
 github.com/andybalholm/brotli v1.2.1 h1:R+f5xP285VArJDRgowrfb9DqL18yVK0gKAW/F+eTWro=
 github.com/andybalholm/brotli v1.2.1/go.mod h1:rzTDkvFWvIrjDXZHkuS16NPggd91W3kUSvPlQ1pLaKY=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/dlclark/regexp2 v1.12.0 h1:0j4c5qQmnC6XOWNjP3PIXURXN2gWx76rd3KvgdPkCz8=
-github.com/dlclark/regexp2 v1.12.0/go.mod h1:DHkYz0B9wPfa6wondMfaivmHpzrQ3v9q8cnmRbL6yW8=
-github.com/dop251/goja v0.0.0-20260311135729-065cd970411c h1:OcLmPfx1T1RmZVHHFwWMPaZDdRf0DBMZOFMVWJa7Pdk=
-github.com/dop251/goja v0.0.0-20260311135729-065cd970411c/go.mod h1:MxLav0peU43GgvwVgNbLAj1s/bSGboKkhuULvq/7hx4=
+github.com/dlclark/regexp2/v2 v2.2.2 h1:MYWvNYw8okuqNhwTYO587EZMiDruVa2vhV6fsGpfya0=
+github.com/dlclark/regexp2/v2 v2.2.2/go.mod h1:avUrQvPaLz2DrFNHJF0taWAFFX2C1GMSSoeiqFjcBmU=
+github.com/dop251/goja v0.0.0-20260618133527-c9b2ea77db59 h1:DjKLmvKK9u15djHZ88N8M0DhgnHVgJJ8bnEe0h7Lga8=
+github.com/dop251/goja v0.0.0-20260618133527-c9b2ea77db59/go.mod h1:Sc+QOu1WruvaaeT/cxFez/pXHpI9ZDjg/E8QNfSVveI=
 github.com/go-flac/flacpicture/v2 v2.0.2 h1:HCaJIVZpxnpdWs6G3ECEVRelzqS5xOi1Ba1AGmtXbzE=
 github.com/go-flac/flacpicture/v2 v2.0.2/go.mod h1:DMZBPWPAmdLqNhqFSy5ZBs9wyBzOekXutGfP7/TFCuo=
 github.com/go-flac/flacvorbis/v2 v2.0.2 h1:xCL3OhxrxWkHrbWUBvGNe+6FQ03yLmBbz0v5z4V2PoQ=
@@ -16,10 +16,12 @@ github.com/go-flac/go-flac/v2 v2.0.4 h1:atf/kFa8U9idtkA//NO22XGr+MzQLeXZecnmP9sY
 github.com/go-flac/go-flac/v2 v2.0.4/go.mod h1:sYOlTKxutMW0RDYF+KlD6Zn+VOCZlIFQG/r/usPveCs=
 github.com/go-sourcemap/sourcemap v2.1.4+incompatible h1:a+iTbH5auLKxaNwQFg0B+TCYl6lbukKPc7b5x0n1s6Q=
 github.com/go-sourcemap/sourcemap v2.1.4+incompatible/go.mod h1:F8jJfvm2KbVjc5NqelyYJmf/v5J0dwNLS2mL4sNA1Jg=
+github.com/goccy/go-yaml v1.19.2 h1:PmFC1S6h8ljIz6gMRBopkjP1TVT7xuwrButHID66PoM=
+github.com/goccy/go-yaml v1.19.2/go.mod h1:XBurs7gK8ATbW4ZPGKgcbrY1Br56PdM69F7LkFRi1kA=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
-github.com/google/pprof v0.0.0-20260507013755-92041b743c96 h1:YDDnaZ9afWajDboPMt9Vikqca/yWAX7KAxVzb4lJU1M=
-github.com/google/pprof v0.0.0-20260507013755-92041b743c96/go.mod h1:MxpfABSjhmINe3F1It9d+8exIHFvUqtLIRCdOGNXqiI=
+github.com/google/pprof v0.0.0-20260604005048-7023385849c0 h1:h1QTMDl6q9wDvDCJVpKQSjgleGFYnd2fOxmg2K+6BGE=
+github.com/google/pprof v0.0.0-20260604005048-7023385849c0/go.mod h1:MxpfABSjhmINe3F1It9d+8exIHFvUqtLIRCdOGNXqiI=
 github.com/klauspost/compress v1.18.6 h1:2jupLlAwFm95+YDR+NwD2MEfFO9d4z4Prjl1XXDjuao=
 github.com/klauspost/compress v1.18.6/go.mod h1:cwPg85FWrGar70rWktvGQj8/hthj3wpl0PGDogxkrSQ=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
@@ -30,23 +32,21 @@ github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOf
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/xyproto/randomstring v1.0.5 h1:YtlWPoRdgMu3NZtP45drfy1GKoojuR7hmRcnhZqKjWU=
 github.com/xyproto/randomstring v1.0.5/go.mod h1:rgmS5DeNXLivK7YprL0pY+lTuhNQW3iGxZ18UQApw/E=
-golang.org/x/crypto v0.52.0 h1:RMs7fP2rXdep0CftQlK8Uf+kibLm7qkCcradZWYz988=
-golang.org/x/crypto v0.52.0/go.mod h1:1QgfPxDqh0T2M/elOJtp9RvuR95kVjir0e6/BvEmGbc=
-golang.org/x/mobile v0.0.0-20260529142300-ecb4cd65260a h1:sEcsLeiCTTaHGWn+v81+PLAOzzOA9wmzNRqr1WfCmVY=
-golang.org/x/mobile v0.0.0-20260529142300-ecb4cd65260a/go.mod h1:ltIbhcRzKgwHa4ZxKJeiv0nyzcXUUYCqMyO0Y+vPmXw=
-golang.org/x/mod v0.36.0 h1:JJjpVx6myfUsUdAzZuOSTTmRE0PfZeNWzzvKrP7amb4=
-golang.org/x/mod v0.36.0/go.mod h1:moc6ELqsWcOw5Ef3xVprK5ul/MvtVvkIXLziUOICjUQ=
-golang.org/x/net v0.55.0 h1:bcvxaJn3e1U6InsFWt1JUq1aSjnRxLzT2rtD2KfkDF8=
-golang.org/x/net v0.55.0/go.mod h1:L5U2KuzuOe1lY7Z+aWVIKK6qEeJXnXV9yzGA+WCHJww=
-golang.org/x/sync v0.20.0 h1:e0PTpb7pjO8GAtTs2dQ6jYa5BWYlMuX047Dco/pItO4=
-golang.org/x/sync v0.20.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
-golang.org/x/sys v0.45.0 h1:dO4czNzziLiiXplLQgBCEpCvXQ3dnkn0SdaZSYdQ+FY=
-golang.org/x/sys v0.45.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
-golang.org/x/text v0.37.0 h1:Cqjiwd9eSg8e0QAkyCaQTNHFIIzWtidPahFWR83rTrc=
-golang.org/x/text v0.37.0/go.mod h1:a5sjxXGs9hsn/AJVwuElvCAo9v8QYLzvavO5z2PiM38=
-golang.org/x/tools v0.45.0 h1:18qN3FAooORvApf5XjCXgsuayZOEtXf6JK18I3+ONa8=
-golang.org/x/tools v0.45.0/go.mod h1:LuUGqqaXcXMEFEruIVJVm5mgDD8vww/z/SR1gQ4uE/0=
-gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
-gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
+golang.org/x/crypto v0.53.0 h1:QZ4Muo8THX6CizN2vPPd5fBGHyogrdK9fG4wLPFUsto=
+golang.org/x/crypto v0.53.0/go.mod h1:DNLU434OwVakk9PzuwV8w62mAJpRJL3vsgcfp4Qnsio=
+golang.org/x/mobile v0.0.0-20260611195102-4dd8f1dbf5d2 h1:zoM1gIKhVkcQNm43kad8OHLgPNoJ12xIqmxHtKr8Mug=
+golang.org/x/mobile v0.0.0-20260611195102-4dd8f1dbf5d2/go.mod h1:QGMqsqLn6orFQ/ksqYMf+Fa33Soa1vPoHEd0Pj7N+lQ=
+golang.org/x/mod v0.37.0 h1:vF1DjpVEshcIqoEaauuHebaLk1O1forxjxBaVn884JQ=
+golang.org/x/mod v0.37.0/go.mod h1:m8S8VeM9r4dzDwjrKO0a1sZP3YjeMamRRlD+fmR2Q/0=
+golang.org/x/net v0.56.0 h1:Rw8j/hFzGvJUZwNBXnAtf5sVDVt+65SK2C7IxCxZt5o=
+golang.org/x/net v0.56.0/go.mod h1:D3Ku6r+V6JROoZK144D2XfMHFcMq/0zSfLelVTCFKec=
+golang.org/x/sync v0.21.0 h1:HLII4xRRTtCRkxYp4HNFF0Js/Og6q2i++KXbg0gHCwM=
+golang.org/x/sync v0.21.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
+golang.org/x/sys v0.46.0 h1:noSf2Fq6F8DBgS+LysIkx7rIExoNHJsxOAtPp4rthXw=
+golang.org/x/sys v0.46.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
+golang.org/x/text v0.38.0 h1:sXmwo9DwP3OK9EZ7PqAdaooSGozfl/3a6/xJcbzPRhE=
+golang.org/x/text v0.38.0/go.mod h1:YXZt3QhHUKYT53r2lLKFIVi6Ao1jdzrTR/KQ09qyxF4=
+golang.org/x/tools v0.47.0 h1:7Kn5x/d1svx/PzryTsqeoZN4TZwqeH5pGWjefhLi/1Q=
+golang.org/x/tools v0.47.0/go.mod h1:dFHnyTvFWY212G+h7ZY4Vsp/K3U4/7W9TyVaAul8uCA=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

go_backend/httputil.go

@@ -1,7 +1,9 @@
 package gobackend
 
 import (
+	"context"
 	"crypto/tls"
+	"crypto/x509"
 	"errors"
 	"fmt"
 	"io"
@@ -437,101 +439,143 @@ func (e *ISPBlockingError) Error() string {
 	return fmt.Sprintf("ISP blocking detected for %s: %s", e.Domain, e.Reason)
 }
 
-func IsISPBlocking(err error, requestURL string) *ISPBlockingError {
+// isTransientNetworkError reports retryable transport failures such as
+// timeouts and temporary DNS errors. Permanent DNS misses are excluded.
+func isTransientNetworkError(err error) bool {
 	if err == nil {
-		return nil
+		return false
+	}
+	if errors.Is(err, context.DeadlineExceeded) || errors.Is(err, context.Canceled) {
+		return true
+	}
+	var netErr net.Error
+	return errors.As(err, &netErr) && (netErr.Timeout() || netErr.Temporary())
+}
+
+// isConnectivityFailure reports DNS, dial, timeout, TLS, or truncated transport
+// errors. Application-level API messages are excluded.
+func isConnectivityFailure(err error) bool {
+	return connectivityFailureReason(err) != ""
+}
+
+func connectivityFailureReason(err error) string {
+	if err == nil {
+		return ""
+	}
+	if errors.Is(err, context.DeadlineExceeded) {
+		return "Request timed out - ISP may be throttling"
+	}
+	if errors.Is(err, io.ErrUnexpectedEOF) {
+		return "Connection closed unexpectedly - ISP may be blocking"
 	}
 
-	domain := extractDomain(requestURL)
-	errStr := strings.ToLower(err.Error())
+	var urlErr *url.Error
+	if errors.As(err, &urlErr) {
+		if urlErr.Timeout() {
+			return "Connection timed out - ISP may be blocking access"
+		}
+		if urlErr.Err != nil {
+			if reason := connectivityFailureReason(urlErr.Err); reason != "" {
+				return reason
+			}
+		}
+	}
 
 	var dnsErr *net.DNSError
 	if errors.As(err, &dnsErr) {
-		if dnsErr.IsNotFound || dnsErr.IsTemporary {
-			return &ISPBlockingError{
-				Domain:      domain,
-				Reason:      "DNS resolution failed - domain may be blocked by ISP",
-				OriginalErr: err,
-			}
+		if dnsErr.IsNotFound || dnsErr.IsTimeout || dnsErr.IsTemporary {
+			return "DNS resolution failed - domain may be blocked by ISP"
 		}
 	}
 
 	var opErr *net.OpError
 	if errors.As(err, &opErr) {
-		if opErr.Op == "dial" {
-			var syscallErr syscall.Errno
-			if errors.As(opErr.Err, &syscallErr) {
-				switch syscallErr {
-				case syscall.ECONNREFUSED:
-					return &ISPBlockingError{
-						Domain:      domain,
-						Reason:      "Connection refused - port may be blocked by ISP/firewall",
-						OriginalErr: err,
-					}
-				case syscall.ECONNRESET:
-					return &ISPBlockingError{
-						Domain:      domain,
-						Reason:      "Connection reset - ISP may be intercepting traffic",
-						OriginalErr: err,
-					}
-				case syscall.ETIMEDOUT:
-					return &ISPBlockingError{
-						Domain:      domain,
-						Reason:      "Connection timed out - ISP may be blocking access",
-						OriginalErr: err,
-					}
-				case syscall.ENETUNREACH:
-					return &ISPBlockingError{
-						Domain:      domain,
-						Reason:      "Network unreachable - ISP may be blocking route",
-						OriginalErr: err,
-					}
-				case syscall.EHOSTUNREACH:
-					return &ISPBlockingError{
-						Domain:      domain,
-						Reason:      "Host unreachable - ISP may be blocking destination",
-						OriginalErr: err,
-					}
-				}
+		if opErr.Timeout() {
+			return "Connection timed out - ISP may be blocking access"
+		}
+		var errno syscall.Errno
+		if errors.As(opErr.Err, &errno) {
+			switch errno {
+			case syscall.ECONNREFUSED:
+				return "Connection refused - port may be blocked by ISP/firewall"
+			case syscall.ECONNRESET:
+				return "Connection reset - ISP may be intercepting traffic"
+			case syscall.ETIMEDOUT:
+				return "Connection timed out - ISP may be blocking access"
+			case syscall.ENETUNREACH:
+				return "Network unreachable - ISP may be blocking route"
+			case syscall.EHOSTUNREACH:
+				return "Host unreachable - ISP may be blocking destination"
 			}
 		}
 	}
 
 	var tlsErr *tls.RecordHeaderError
 	if errors.As(err, &tlsErr) {
-		return &ISPBlockingError{
-			Domain:      domain,
-			Reason:      "TLS handshake failed - ISP may be intercepting HTTPS traffic",
-			OriginalErr: err,
+		return "TLS handshake failed - ISP may be intercepting HTTPS traffic"
+	}
+
+	var certErr x509.CertificateInvalidError
+	if errors.As(err, &certErr) {
+		return "Certificate error - ISP may be using MITM proxy"
+	}
+	var hostnameErr x509.HostnameError
+	if errors.As(err, &hostnameErr) {
+		return "Certificate error - ISP may be using MITM proxy"
+	}
+	var unknownAuth x509.UnknownAuthorityError
+	if errors.As(err, &unknownAuth) {
+		return "Certificate error - ISP may be using MITM proxy"
+	}
+
+	return ""
+}
+
+// isTLSHandshakeOrResetError reports TLS handshake/cert failures and TCP resets
+// that should trigger a Chrome fingerprint retry.
+func isTLSHandshakeOrResetError(err error) bool {
+	if err == nil {
+		return false
+	}
+	var recordErr *tls.RecordHeaderError
+	if errors.As(err, &recordErr) {
+		return true
+	}
+	var certErr x509.CertificateInvalidError
+	if errors.As(err, &certErr) {
+		return true
+	}
+	var hostnameErr x509.HostnameError
+	if errors.As(err, &hostnameErr) {
+		return true
+	}
+	var unknownAuth x509.UnknownAuthorityError
+	if errors.As(err, &unknownAuth) {
+		return true
+	}
+	var opErr *net.OpError
+	if errors.As(err, &opErr) {
+		var errno syscall.Errno
+		if errors.As(opErr.Err, &errno) && errno == syscall.ECONNRESET {
+			return true
 		}
 	}
+	return false
+}
 
-	blockingPatterns := []struct {
-		pattern string
-		reason  string
-	}{
-		{"connection reset by peer", "Connection reset - ISP may be intercepting traffic"},
-		{"connection refused", "Connection refused - port may be blocked"},
-		{"no such host", "DNS lookup failed - domain may be blocked by ISP"},
-		{"i/o timeout", "Connection timed out - ISP may be blocking access"},
-		{"network is unreachable", "Network unreachable - ISP may be blocking route"},
-		{"tls: ", "TLS error - ISP may be intercepting HTTPS traffic"},
-		{"certificate", "Certificate error - ISP may be using MITM proxy"},
-		{"eof", "Connection closed unexpectedly - ISP may be blocking"},
-		{"context deadline exceeded", "Request timed out - ISP may be throttling"},
+func IsISPBlocking(err error, requestURL string) *ISPBlockingError {
+	if err == nil {
+		return nil
 	}
-
-	for _, bp := range blockingPatterns {
-		if strings.Contains(errStr, bp.pattern) {
-			return &ISPBlockingError{
-				Domain:      domain,
-				Reason:      bp.reason,
-				OriginalErr: err,
-			}
-		}
+	reason := connectivityFailureReason(err)
+	if reason == "" {
+		return nil
+	}
+	return &ISPBlockingError{
+		Domain:      extractDomain(requestURL),
+		Reason:      reason,
+		OriginalErr: err,
 	}
-
-	return nil
 }
 
 func CheckAndLogISPBlocking(err error, requestURL string, tag string) bool {

go_backend/httputil_supplement_test.go

@@ -1,13 +1,15 @@
 package gobackend
 
 import (
+	"context"
 	"crypto/x509"
 	"encoding/pem"
-	"errors"
 	"io"
+	"net"
 	"net/http"
 	"net/url"
 	"strings"
+	"syscall"
 	"testing"
 	"time"
 )
@@ -131,15 +133,24 @@ func TestHTTPUtilityHelpers(t *testing.T) {
 	if getRetryAfterDuration(&http.Response{Header: http.Header{"Retry-After": []string{"bad"}}}) != 0 {
 		t.Fatal("invalid retry-after should be zero")
 	}
-	if isp := IsISPBlocking(errors.New("connection reset by peer"), "https://example.com/x"); isp == nil || !strings.Contains(isp.Error(), "example.com") {
+	resetErr := &net.OpError{Op: "read", Err: syscall.ECONNRESET}
+	if isp := IsISPBlocking(resetErr, "https://example.com/x"); isp == nil || !strings.Contains(isp.Error(), "example.com") {
 		t.Fatalf("IsISPBlocking = %#v", isp)
 	}
-	if !CheckAndLogISPBlocking(errors.New("i/o timeout"), "https://timeout.example/x", "test") {
+	timeoutErr := &net.OpError{Op: "dial", Err: syscall.ETIMEDOUT}
+	if !CheckAndLogISPBlocking(timeoutErr, "https://timeout.example/x", "test") {
 		t.Fatal("expected logged ISP blocking")
 	}
-	if wrapped := WrapErrorWithISPCheck(errors.New("connection refused"), "https://refused.example/x", "test"); wrapped == nil || !strings.Contains(wrapped.Error(), "ISP blocking") {
+	refusedErr := &net.OpError{Op: "dial", Err: syscall.ECONNREFUSED}
+	if wrapped := WrapErrorWithISPCheck(refusedErr, "https://refused.example/x", "test"); wrapped == nil || !strings.Contains(wrapped.Error(), "ISP blocking") {
 		t.Fatalf("WrapErrorWithISPCheck = %v", wrapped)
 	}
+	if !isTransientNetworkError(context.DeadlineExceeded) || isTransientNetworkError(&net.DNSError{IsNotFound: true}) {
+		t.Fatal("isTransientNetworkError mismatch")
+	}
+	if !isConnectivityFailure(&net.DNSError{IsNotFound: true}) || !isConnectivityFailure(context.DeadlineExceeded) {
+		t.Fatal("isConnectivityFailure mismatch")
+	}
 	if WrapErrorWithISPCheck(nil, "", "test") != nil {
 		t.Fatal("nil wrap should stay nil")
 	}

go_backend/httputil_utls.go

@@ -144,13 +144,7 @@ func DoRequestWithCloudflareBypass(req *http.Request) (*http.Response, error) {
 		return resp, nil
 	}
 
-	errStr := strings.ToLower(err.Error())
-	tlsRelated := strings.Contains(errStr, "tls") ||
-		strings.Contains(errStr, "handshake") ||
-		strings.Contains(errStr, "certificate") ||
-		strings.Contains(errStr, "connection reset")
-
-	if tlsRelated {
+	if isTLSHandshakeOrResetError(err) {
 		LogDebug("HTTP", "TLS error detected, retrying with Chrome TLS fingerprint: %v", err)
 
 		reqCopy := req.Clone(req.Context())

go_backend/library_scan.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strconv"
 	"strings"
 	"sync"
@@ -76,6 +77,9 @@ var supportedAudioFormats = map[string]bool{
 	".ape":  true,
 	".wv":   true,
 	".mpc":  true,
+	".wav":  true,
+	".aiff": true,
+	".aif":  true,
 	".cue":  true,
 }
 
@@ -89,6 +93,18 @@ type scannedCueFileInfo struct {
 	audioPath string
 }
 
+type libraryScanTask struct {
+	index int
+	info  libraryAudioFileInfo
+}
+
+type libraryScanTaskResult struct {
+	index   int
+	path    string
+	results []LibraryScanResult
+	err     error
+}
+
 func isLibraryStagingFile(path string) bool {
 	name := strings.ToLower(filepath.Base(path))
 	if strings.HasSuffix(name, ".partial") {
@@ -147,6 +163,129 @@ func collectLibraryAudioFiles(folderPath string, cancelCh <-chan struct{}) ([]li
 	return files, nil
 }
 
+func libraryScanWorkerCount(taskCount int) int {
+	if taskCount < 16 {
+		return 1
+	}
+	workers := runtime.NumCPU()
+	if workers > 4 {
+		workers = 4
+	}
+	if workers < 2 {
+		workers = 2
+	}
+	if workers > taskCount {
+		workers = taskCount
+	}
+	return workers
+}
+
+func updateLibraryScanProgress(scannedFiles, totalFiles int, currentPath string) {
+	libraryScanProgressMu.Lock()
+	libraryScanProgress.ScannedFiles = scannedFiles
+	libraryScanProgress.CurrentFile = filepath.Base(currentPath)
+	if totalFiles > 0 {
+		libraryScanProgress.ProgressPct = float64(scannedFiles) / float64(totalFiles) * 100
+	}
+	libraryScanProgressMu.Unlock()
+}
+
+func scanLibraryAudioTasksParallel(tasks []libraryScanTask, scanTime string, cancelCh <-chan struct{}, totalFiles int, completed *int) (map[int][]LibraryScanResult, int, error) {
+	resultsByIndex := make(map[int][]LibraryScanResult, len(tasks))
+	if len(tasks) == 0 {
+		return resultsByIndex, 0, nil
+	}
+
+	workers := libraryScanWorkerCount(len(tasks))
+	if workers <= 1 {
+		errorCount := 0
+		for _, task := range tasks {
+			select {
+			case <-cancelCh:
+				return resultsByIndex, errorCount, fmt.Errorf("scan cancelled")
+			default:
+			}
+			result, err := scanAudioFileWithKnownModTime(task.info.path, scanTime, task.info.modTime)
+			*completed++
+			updateLibraryScanProgress(*completed, totalFiles, task.info.path)
+			if err != nil {
+				errorCount++
+				GoLog("[LibraryScan] Error scanning %s: %v\n", task.info.path, err)
+				continue
+			}
+			resultsByIndex[task.index] = []LibraryScanResult{*result}
+		}
+		return resultsByIndex, errorCount, nil
+	}
+
+	taskCh := make(chan libraryScanTask)
+	resultCh := make(chan libraryScanTaskResult, workers)
+	var wg sync.WaitGroup
+
+	for i := 0; i < workers; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for task := range taskCh {
+				select {
+				case <-cancelCh:
+					return
+				default:
+				}
+				result, err := scanAudioFileWithKnownModTime(task.info.path, scanTime, task.info.modTime)
+				taskResult := libraryScanTaskResult{
+					index: task.index,
+					path:  task.info.path,
+					err:   err,
+				}
+				if err == nil && result != nil {
+					taskResult.results = []LibraryScanResult{*result}
+				}
+				select {
+				case <-cancelCh:
+					return
+				case resultCh <- taskResult:
+				}
+			}
+		}()
+	}
+
+	go func() {
+		defer close(taskCh)
+		for _, task := range tasks {
+			select {
+			case <-cancelCh:
+				return
+			case taskCh <- task:
+			}
+		}
+	}()
+
+	go func() {
+		wg.Wait()
+		close(resultCh)
+	}()
+
+	errorCount := 0
+	for taskResult := range resultCh {
+		*completed++
+		updateLibraryScanProgress(*completed, totalFiles, taskResult.path)
+		if taskResult.err != nil {
+			errorCount++
+			GoLog("[LibraryScan] Error scanning %s: %v\n", taskResult.path, taskResult.err)
+			continue
+		}
+		resultsByIndex[taskResult.index] = taskResult.results
+	}
+
+	select {
+	case <-cancelCh:
+		return resultsByIndex, errorCount, fmt.Errorf("scan cancelled")
+	default:
+	}
+	return resultsByIndex, errorCount, nil
+}
+
 func SetLibraryCoverCacheDir(cacheDir string) {
 	libraryCoverCacheMu.Lock()
 	libraryCoverCacheDir = cacheDir
@@ -222,6 +361,10 @@ func ScanLibraryFolder(folderPath string) (string, error) {
 		}
 	}
 
+	resultsByIndex := make(map[int][]LibraryScanResult, totalFiles)
+	audioTasks := make([]libraryScanTask, 0, totalFiles)
+	completedFiles := 0
+
 	for i, fileInfo := range audioFileInfos {
 		filePath := fileInfo.path
 		select {
@@ -230,12 +373,6 @@ func ScanLibraryFolder(folderPath string) (string, error) {
 		default:
 		}
 
-		libraryScanProgressMu.Lock()
-		libraryScanProgress.ScannedFiles = i + 1
-		libraryScanProgress.CurrentFile = filepath.Base(filePath)
-		libraryScanProgress.ProgressPct = float64(i+1) / float64(totalFiles) * 100
-		libraryScanProgressMu.Unlock()
-
 		ext := strings.ToLower(filepath.Ext(filePath))
 
 		if ext == ".cue" {
@@ -257,26 +394,44 @@ func ScanLibraryFolder(folderPath string) (string, error) {
 			if err != nil {
 				errorCount++
 				GoLog("[LibraryScan] Error scanning cue %s: %v\n", filePath, err)
+				completedFiles++
+				updateLibraryScanProgress(completedFiles, totalFiles, filePath)
 				continue
 			}
-			results = append(results, cueResults...)
+			resultsByIndex[i] = cueResults
+			completedFiles++
+			updateLibraryScanProgress(completedFiles, totalFiles, filePath)
 			GoLog("[LibraryScan] CUE sheet %s: %d tracks\n", filepath.Base(filePath), len(cueResults))
 			continue
 		}
 
 		if cueReferencedAudioFiles[filePath] {
+			completedFiles++
+			updateLibraryScanProgress(completedFiles, totalFiles, filePath)
 			GoLog("[LibraryScan] Skipping %s (referenced by .cue sheet)\n", filepath.Base(filePath))
 			continue
 		}
 
-		result, err := scanAudioFileWithKnownModTime(filePath, scanTime, fileInfo.modTime)
-		if err != nil {
-			errorCount++
-			GoLog("[LibraryScan] Error scanning %s: %v\n", filePath, err)
-			continue
-		}
+		audioTasks = append(audioTasks, libraryScanTask{index: i, info: fileInfo})
+	}
 
-		results = append(results, *result)
+	audioResults, audioErrors, err := scanLibraryAudioTasksParallel(
+		audioTasks,
+		scanTime,
+		cancelCh,
+		totalFiles,
+		&completedFiles,
+	)
+	if err != nil {
+		return "[]", err
+	}
+	errorCount += audioErrors
+	for index, scanResults := range audioResults {
+		resultsByIndex[index] = scanResults
+	}
+
+	for i := range audioFileInfos {
+		results = append(results, resultsByIndex[i]...)
 	}
 
 	libraryScanProgressMu.Lock()
@@ -340,6 +495,10 @@ func scanAudioFileWithKnownModTimeAndDisplayNameAndCoverCacheKey(filePath, displ
 		return scanOggFile(filePath, result, displayNameHint)
 	case ".ape", ".wv", ".mpc":
 		return scanAPEFile(filePath, result, displayNameHint)
+	case ".wav":
+		return scanWAVFile(filePath, result, displayNameHint)
+	case ".aiff", ".aif", ".aifc":
+		return scanAIFFFile(filePath, result, displayNameHint)
 	default:
 		return scanFromFilename(filePath, displayNameHint, result)
 	}
@@ -479,7 +638,7 @@ func libraryFormatForM4ACodec(codec string) string {
 
 func isLosslessLibraryFormat(format string) bool {
 	switch strings.ToLower(strings.TrimSpace(format)) {
-	case "flac", "alac":
+	case "flac", "alac", "wav", "aiff", "aif", "aifc":
 		return true
 	default:
 		return false
@@ -867,6 +1026,10 @@ func scanLibraryFolderIncrementalWithExistingFiles(folderPath string, existingFi
 		}
 	}
 
+	resultsByIndex := make(map[int][]LibraryScanResult, len(filesToScan))
+	audioTasks := make([]libraryScanTask, 0, len(filesToScan))
+	completedFiles := skippedCount
+
 	for i, f := range filesToScan {
 		select {
 		case <-cancelCh:
@@ -874,12 +1037,6 @@ func scanLibraryFolderIncrementalWithExistingFiles(folderPath string, existingFi
 		default:
 		}
 
-		libraryScanProgressMu.Lock()
-		libraryScanProgress.ScannedFiles = skippedCount + i + 1
-		libraryScanProgress.CurrentFile = filepath.Base(f.path)
-		libraryScanProgress.ProgressPct = float64(skippedCount+i+1) / float64(totalFiles) * 100
-		libraryScanProgressMu.Unlock()
-
 		ext := strings.ToLower(filepath.Ext(f.path))
 
 		if ext == ".cue" {
@@ -901,24 +1058,42 @@ func scanLibraryFolderIncrementalWithExistingFiles(folderPath string, existingFi
 			if err != nil {
 				errorCount++
 				GoLog("[LibraryScan] Error scanning cue %s: %v\n", f.path, err)
+				completedFiles++
+				updateLibraryScanProgress(completedFiles, totalFiles, f.path)
 				continue
 			}
-			results = append(results, cueResults...)
+			resultsByIndex[i] = cueResults
+			completedFiles++
+			updateLibraryScanProgress(completedFiles, totalFiles, f.path)
 			continue
 		}
 
 		if cueReferencedAudioFilesInc[f.path] {
+			completedFiles++
+			updateLibraryScanProgress(completedFiles, totalFiles, f.path)
 			continue
 		}
 
-		result, err := scanAudioFileWithKnownModTime(f.path, scanTime, f.modTime)
-		if err != nil {
-			errorCount++
-			GoLog("[LibraryScan] Error scanning %s: %v\n", f.path, err)
-			continue
-		}
+		audioTasks = append(audioTasks, libraryScanTask{index: i, info: f})
+	}
 
-		results = append(results, *result)
+	audioResults, audioErrors, err := scanLibraryAudioTasksParallel(
+		audioTasks,
+		scanTime,
+		cancelCh,
+		totalFiles,
+		&completedFiles,
+	)
+	if err != nil {
+		return "{}", err
+	}
+	errorCount += audioErrors
+	for index, scanResults := range audioResults {
+		resultsByIndex[index] = scanResults
+	}
+
+	for i := range filesToScan {
+		results = append(results, resultsByIndex[i]...)
 	}
 
 	libraryScanProgressMu.Lock()

go_backend/lyrics.go

@@ -20,6 +20,12 @@ const (
 	durationToleranceSec = 10.0
 )
 
+const (
+	lyricsProviderUnavailableCooldown = 10 * time.Minute
+	lyricsProviderParallelism         = 3
+	lyricsProviderPriorityGrace       = 5000 * time.Millisecond
+)
+
 const (
 	LyricsProviderLRCLIB     = "lrclib"
 	LyricsProviderNetease    = "netease"
@@ -31,6 +37,7 @@ const (
 	LyricsProviderYouTube    = "youtube"
 	LyricsProviderKugou      = "kugou"
 	LyricsProviderGenius     = "genius"
+	LyricsProviderLyricsPlus = "lyricsplus"
 )
 
 var DefaultLyricsProviders = []string{
@@ -45,6 +52,33 @@ var (
 	appVersion        string
 )
 
+type lyricsProviderHealthEntry struct {
+	unavailableUntil time.Time
+	reason           string
+}
+
+type lyricsProviderSearchRequest struct {
+	spotifyID       string
+	trackName       string
+	artistName      string
+	primaryArtist   string
+	simplifiedTrack string
+	durationSec     float64
+	fetchOptions    LyricsFetchOptions
+}
+
+type lyricsProviderSearchResult struct {
+	index        int
+	providerName string
+	lyrics       *LyricsResponse
+	err          error
+}
+
+var (
+	lyricsProviderHealthMu sync.RWMutex
+	lyricsProviderHealth   = make(map[string]lyricsProviderHealthEntry)
+)
+
 func SetAppVersion(version string) {
 	normalized := strings.TrimSpace(version)
 
@@ -98,6 +132,7 @@ func SetLyricsProviderOrder(providers []string) {
 
 	if len(providers) == 0 {
 		lyricsProviders = nil
+		clearLyricsProviderHealth()
 		return
 	}
 
@@ -112,6 +147,7 @@ func SetLyricsProviderOrder(providers []string) {
 		LyricsProviderYouTube:    true,
 		LyricsProviderKugou:      true,
 		LyricsProviderGenius:     true,
+		LyricsProviderLyricsPlus: true,
 	}
 
 	var valid []string
@@ -123,9 +159,131 @@ func SetLyricsProviderOrder(providers []string) {
 	}
 
 	lyricsProviders = valid
+	clearLyricsProviderHealth()
 	GoLog("[Lyrics] Provider order set to: %v\n", valid)
 }
 
+func clearLyricsProviderHealth() {
+	lyricsProviderHealthMu.Lock()
+	defer lyricsProviderHealthMu.Unlock()
+	lyricsProviderHealth = make(map[string]lyricsProviderHealthEntry)
+}
+
+func lyricsProviderHealthKey(providerName string) string {
+	return strings.ToLower(strings.TrimSpace(providerName))
+}
+
+func shouldSkipLyricsProvider(providerName string) (bool, time.Duration, string) {
+	key := lyricsProviderHealthKey(providerName)
+	if key == "" {
+		return false, 0, ""
+	}
+
+	now := time.Now()
+	lyricsProviderHealthMu.RLock()
+	entry, ok := lyricsProviderHealth[key]
+	lyricsProviderHealthMu.RUnlock()
+	if !ok {
+		return false, 0, ""
+	}
+	if !now.Before(entry.unavailableUntil) {
+		lyricsProviderHealthMu.Lock()
+		if current, exists := lyricsProviderHealth[key]; exists && !now.Before(current.unavailableUntil) {
+			delete(lyricsProviderHealth, key)
+		}
+		lyricsProviderHealthMu.Unlock()
+		return false, 0, ""
+	}
+	return true, time.Until(entry.unavailableUntil), entry.reason
+}
+
+func markLyricsProviderAvailable(providerName string) {
+	key := lyricsProviderHealthKey(providerName)
+	if key == "" {
+		return
+	}
+	lyricsProviderHealthMu.Lock()
+	delete(lyricsProviderHealth, key)
+	lyricsProviderHealthMu.Unlock()
+}
+
+func markLyricsProviderUnavailable(providerName string, err error) {
+	if err == nil || !isLyricsProviderUnavailableError(err) {
+		return
+	}
+	key := lyricsProviderHealthKey(providerName)
+	if key == "" {
+		return
+	}
+	reason := strings.TrimSpace(err.Error())
+	if len(reason) > 160 {
+		reason = reason[:160]
+	}
+	unavailableUntil := time.Now().Add(lyricsProviderUnavailableCooldown)
+
+	lyricsProviderHealthMu.Lock()
+	lyricsProviderHealth[key] = lyricsProviderHealthEntry{
+		unavailableUntil: unavailableUntil,
+		reason:           reason,
+	}
+	lyricsProviderHealthMu.Unlock()
+	GoLog("[Lyrics] Provider %s marked unavailable for %s: %s\n", providerName, lyricsProviderUnavailableCooldown, reason)
+}
+
+var lyricsNotFoundSignals = []string{
+	"lyrics not found",
+	"no lyrics found",
+	"no songs found",
+	"not found on",
+	"empty track",
+	"empty search query",
+	"needs a deezer id",
+}
+
+// Provider/API-level failures that should temporarily disable a lyrics source.
+// Transport failures are handled by isConnectivityFailure via typed errors.
+var lyricsServiceUnavailableSignals = []string{
+	"fetch failed",
+	"missing required parameters",
+	"request failed",
+	"request unsuccessful",
+	"search failed",
+	"search unavailable",
+	"rate limit",
+	"too many requests",
+	"operation too frequent",
+	"操作频繁",
+	"proxy returned http 429",
+	"proxy returned http 5",
+	"unexpected status code: 429",
+	"unexpected status code: 5",
+	"unexpected response code",
+	"returned http 429",
+	"returned http 5",
+}
+
+func isLyricsProviderUnavailableError(err error) bool {
+	if err == nil {
+		return false
+	}
+
+	msg := strings.ToLower(err.Error())
+	for _, signal := range lyricsNotFoundSignals {
+		if strings.Contains(msg, signal) {
+			return false
+		}
+	}
+	if isConnectivityFailure(err) {
+		return true
+	}
+	for _, signal := range lyricsServiceUnavailableSignals {
+		if strings.Contains(msg, signal) {
+			return true
+		}
+	}
+	return false
+}
+
 func GetLyricsProviderOrder() []string {
 	lyricsProvidersMu.RLock()
 	defer lyricsProvidersMu.RUnlock()
@@ -151,6 +309,7 @@ func GetAvailableLyricsProviders() []map[string]interface{} {
 		{"id": LyricsProviderYouTube, "name": "YouTube", "has_proxy_dependency": true, "description": "YouTube lyrics"},
 		{"id": LyricsProviderKugou, "name": "Kugou", "has_proxy_dependency": true, "description": "Kugou lyrics"},
 		{"id": LyricsProviderGenius, "name": "Genius", "has_proxy_dependency": true, "description": "Genius lyrics"},
+		{"id": LyricsProviderLyricsPlus, "name": "LyricsPlus", "has_proxy_dependency": true, "description": "Word-by-word karaoke lyrics (Apple/Musixmatch/Spotify/QQ)"},
 	}
 }
 
@@ -471,15 +630,22 @@ func (c *LyricsClient) FetchLyricsAllSources(spotifyID, trackName, artistName st
 
 	if len(extensionProviders) > 0 {
 		for _, provider := range extensionProviders {
+			providerName := "extension:" + provider.extension.ID
+			if skip, remaining, reason := shouldSkipLyricsProvider(providerName); skip {
+				GoLog("[Lyrics] Skipping unavailable extension lyrics provider %s for %s: %s\n", provider.extension.ID, remaining.Round(time.Second), reason)
+				continue
+			}
 			GoLog("[Lyrics] Trying extension lyrics provider: %s\n", provider.extension.ID)
 			lyrics, err := provider.FetchLyrics(trackName, artistName, "", durationSec)
 			if err == nil && isValidResult(lyrics) {
 				GoLog("[Lyrics] Got lyrics from extension: %s\n", provider.extension.ID)
+				markLyricsProviderAvailable(providerName)
 				globalLyricsCache.Set(artistName, trackName, durationSec, lyrics)
 				return lyrics, nil
 			}
 			if err != nil {
 				GoLog("[Lyrics] Extension %s failed: %v\n", provider.extension.ID, err)
+				markLyricsProviderUnavailable(providerName, err)
 			}
 		}
 	}
@@ -493,144 +659,338 @@ func (c *LyricsClient) FetchLyricsAllSources(spotifyID, trackName, artistName st
 
 	providerOrder := GetLyricsProviderOrder()
 	simplifiedTrack := simplifyTrackName(trackName)
+	request := lyricsProviderSearchRequest{
+		spotifyID:       spotifyID,
+		trackName:       trackName,
+		artistName:      artistName,
+		primaryArtist:   primaryArtist,
+		simplifiedTrack: simplifiedTrack,
+		durationSec:     durationSec,
+		fetchOptions:    fetchOptions,
+	}
 
 	GoLog("[Lyrics] Searching for: %s - %s (providers: %v)\n", artistName, trackName, providerOrder)
 
-	for _, providerName := range providerOrder {
-		GoLog("[Lyrics] Trying provider: %s\n", providerName)
+	lyrics, err := fetchBuiltInLyricsProviders(providerOrder, request, c.fetchBuiltInLyricsProvider)
+	if err == nil && isValidResult(lyrics) {
+		globalLyricsCache.Set(artistName, trackName, durationSec, lyrics)
+		return lyrics, nil
+	}
 
-		var lyrics *LyricsResponse
-		var err error
+	return nil, fmt.Errorf("lyrics not found from any source")
+}
 
-		switch providerName {
-		case LyricsProviderLRCLIB:
-			lyrics, err = c.tryLRCLIB(primaryArtist, artistName, trackName, simplifiedTrack, durationSec)
+func fetchBuiltInLyricsProviders(
+	providerOrder []string,
+	request lyricsProviderSearchRequest,
+	fetchProvider func(string, lyricsProviderSearchRequest) (*LyricsResponse, error, bool),
+) (*LyricsResponse, error) {
+	type providerCandidate struct {
+		index int
+		name  string
+	}
 
-		case LyricsProviderNetease:
-			neteaseClient := NewNeteaseClient()
-			lyrics, err = neteaseClient.FetchLyrics(
-				trackName,
-				primaryArtist,
-				durationSec,
-				fetchOptions.IncludeTranslationNetease,
-				fetchOptions.IncludeRomanizationNetease,
-			)
-			if err != nil && primaryArtist != artistName {
-				lyrics, err = neteaseClient.FetchLyrics(
-					trackName,
-					artistName,
-					durationSec,
-					fetchOptions.IncludeTranslationNetease,
-					fetchOptions.IncludeRomanizationNetease,
-				)
-			}
-			if err != nil && simplifiedTrack != trackName {
-				lyrics, err = neteaseClient.FetchLyrics(
-					simplifiedTrack,
-					primaryArtist,
-					durationSec,
-					fetchOptions.IncludeTranslationNetease,
-					fetchOptions.IncludeRomanizationNetease,
-				)
-			}
+	candidates := make([]providerCandidate, 0, len(providerOrder))
+	results := make(chan lyricsProviderSearchResult, len(providerOrder))
+	sem := make(chan struct{}, lyricsProviderParallelism)
+	var wg sync.WaitGroup
 
-		case LyricsProviderMusixmatch:
-			musixmatchClient := NewMusixmatchClient()
-			lyrics, err = musixmatchClient.FetchLyrics(
-				trackName,
-				primaryArtist,
-				durationSec,
-				fetchOptions.MusixmatchLanguage,
-			)
-			if err != nil && primaryArtist != artistName {
-				lyrics, err = musixmatchClient.FetchLyrics(
-					trackName,
-					artistName,
-					durationSec,
-					fetchOptions.MusixmatchLanguage,
-				)
-			}
+	for index, providerName := range providerOrder {
+		if skip, remaining, reason := shouldSkipLyricsProvider(providerName); skip {
+			GoLog("[Lyrics] Skipping unavailable provider %s for %s: %s\n", providerName, remaining.Round(time.Second), reason)
+			continue
+		}
 
-		case LyricsProviderAppleMusic:
-			appleClient := NewAppleMusicClient()
-			lyrics, err = appleClient.FetchLyrics(trackName, primaryArtist, durationSec, fetchOptions.MultiPersonWordByWord, fetchOptions.AppleElrcWordSync)
-			if err != nil && primaryArtist != artistName {
-				lyrics, err = appleClient.FetchLyrics(trackName, artistName, durationSec, fetchOptions.MultiPersonWordByWord, fetchOptions.AppleElrcWordSync)
-			}
-
-		case LyricsProviderQQMusic:
-			qqClient := NewQQMusicClient()
-			lyrics, err = qqClient.FetchLyrics(trackName, primaryArtist, durationSec, fetchOptions.MultiPersonWordByWord)
-			if err != nil && primaryArtist != artistName {
-				lyrics, err = qqClient.FetchLyrics(trackName, artistName, durationSec, fetchOptions.MultiPersonWordByWord)
-			}
-
-		case LyricsProviderSpotify:
-			spotifyClient := NewSpotifyLyricsClient()
-			lyrics, err = spotifyClient.FetchLyrics(spotifyID, trackName, primaryArtist, durationSec)
-			if err != nil && primaryArtist != artistName {
-				lyrics, err = spotifyClient.FetchLyrics(spotifyID, trackName, artistName, durationSec)
-			}
-			if err != nil && simplifiedTrack != trackName {
-				lyrics, err = spotifyClient.FetchLyrics("", simplifiedTrack, primaryArtist, durationSec)
-			}
-
-		case LyricsProviderDeezer:
-			deezerClient := NewDeezerLyricsClient()
-			lyrics, err = deezerClient.FetchLyrics(spotifyID, trackName, primaryArtist, durationSec)
-			if err != nil && primaryArtist != artistName {
-				lyrics, err = deezerClient.FetchLyrics(spotifyID, trackName, artistName, durationSec)
-			}
-
-		case LyricsProviderYouTube:
-			youtubeClient := NewYouTubeLyricsClient()
-			lyrics, err = youtubeClient.FetchLyrics(trackName, primaryArtist, durationSec)
-			if err != nil && primaryArtist != artistName {
-				lyrics, err = youtubeClient.FetchLyrics(trackName, artistName, durationSec)
-			}
-			if err != nil && simplifiedTrack != trackName {
-				lyrics, err = youtubeClient.FetchLyrics(simplifiedTrack, primaryArtist, durationSec)
-			}
-
-		case LyricsProviderKugou:
-			kugouClient := NewKugouLyricsClient()
-			lyrics, err = kugouClient.FetchLyrics(trackName, primaryArtist, durationSec)
-			if err != nil && primaryArtist != artistName {
-				lyrics, err = kugouClient.FetchLyrics(trackName, artistName, durationSec)
-			}
-			if err != nil && simplifiedTrack != trackName {
-				lyrics, err = kugouClient.FetchLyrics(simplifiedTrack, primaryArtist, durationSec)
-			}
-
-		case LyricsProviderGenius:
-			geniusClient := NewGeniusLyricsClient()
-			lyrics, err = geniusClient.FetchLyrics(trackName, primaryArtist, durationSec)
-			if err != nil && primaryArtist != artistName {
-				lyrics, err = geniusClient.FetchLyrics(trackName, artistName, durationSec)
-			}
-			if err != nil && simplifiedTrack != trackName {
-				lyrics, err = geniusClient.FetchLyrics(simplifiedTrack, primaryArtist, durationSec)
-			}
-
-		default:
+		knownProvider := isKnownBuiltInLyricsProvider(providerName)
+		if !knownProvider {
 			GoLog("[Lyrics] Unknown provider: %s, skipping\n", providerName)
 			continue
 		}
 
-		if err == nil && isValidResult(lyrics) {
-			GoLog("[Lyrics] Got lyrics from: %s\n", providerName)
-			globalLyricsCache.Set(artistName, trackName, durationSec, lyrics)
-			return lyrics, nil
+		candidate := providerCandidate{index: index, name: providerName}
+		candidates = append(candidates, candidate)
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			sem <- struct{}{}
+			defer func() { <-sem }()
+
+			GoLog("[Lyrics] Trying provider: %s\n", candidate.name)
+			lyrics, err, ok := fetchProvider(candidate.name, request)
+			if !ok {
+				results <- lyricsProviderSearchResult{index: candidate.index, providerName: candidate.name, err: fmt.Errorf("unknown provider")}
+				return
+			}
+			if err == nil && lyricsHasUsableText(lyrics) {
+				GoLog("[Lyrics] Got lyrics from: %s\n", candidate.name)
+				markLyricsProviderAvailable(candidate.name)
+			} else if err != nil {
+				GoLog("[Lyrics] Provider %s failed: %v\n", candidate.name, err)
+				markLyricsProviderUnavailable(candidate.name, err)
+			}
+			results <- lyricsProviderSearchResult{index: candidate.index, providerName: candidate.name, lyrics: lyrics, err: err}
+		}()
+	}
+
+	if len(candidates) == 0 {
+		return nil, fmt.Errorf("lyrics not found from any source")
+	}
+
+	go func() {
+		wg.Wait()
+		close(results)
+	}()
+
+	completed := make(map[int]bool, len(candidates))
+	var best *lyricsProviderSearchResult
+	var lastErr error
+	var graceTimer *time.Timer
+	var grace <-chan time.Time
+
+	stopGrace := func() {
+		if graceTimer != nil {
+			if !graceTimer.Stop() {
+				select {
+				case <-graceTimer.C:
+				default:
+				}
+			}
+			graceTimer = nil
+			grace = nil
+		}
+	}
+	defer stopGrace()
+
+	hasPendingEarlier := func(index int) bool {
+		for _, candidate := range candidates {
+			if candidate.index >= index {
+				return false
+			}
+			if !completed[candidate.index] {
+				return true
+			}
+		}
+		return false
+	}
+
+	for remaining := len(candidates); remaining > 0; {
+		if best != nil && !hasPendingEarlier(best.index) {
+			return best.lyrics, nil
+		}
+		if best != nil && graceTimer == nil {
+			graceTimer = time.NewTimer(lyricsProviderPriorityGrace)
+			grace = graceTimer.C
 		}
 
-		if err != nil {
-			GoLog("[Lyrics] Provider %s failed: %v\n", providerName, err)
+		select {
+		case result, ok := <-results:
+			if !ok {
+				remaining = 0
+				break
+			}
+			remaining--
+			completed[result.index] = true
+			if result.err != nil {
+				lastErr = result.err
+			}
+			if lyricsHasUsableText(result.lyrics) && (best == nil || result.index < best.index) {
+				copied := result
+				best = &copied
+				stopGrace()
+			}
+		case <-grace:
+			if best != nil {
+				GoLog("[Lyrics] Returning provider %s after %s priority grace\n", best.providerName, lyricsProviderPriorityGrace)
+				return best.lyrics, nil
+			}
 		}
 	}
 
+	if best != nil {
+		return best.lyrics, nil
+	}
+	if lastErr != nil {
+		return nil, lastErr
+	}
 	return nil, fmt.Errorf("lyrics not found from any source")
 }
 
+func isKnownBuiltInLyricsProvider(providerName string) bool {
+	switch providerName {
+	case LyricsProviderLRCLIB,
+		LyricsProviderNetease,
+		LyricsProviderMusixmatch,
+		LyricsProviderAppleMusic,
+		LyricsProviderQQMusic,
+		LyricsProviderSpotify,
+		LyricsProviderDeezer,
+		LyricsProviderYouTube,
+		LyricsProviderKugou,
+		LyricsProviderGenius,
+		LyricsProviderLyricsPlus:
+		return true
+	default:
+		return false
+	}
+}
+
+func (c *LyricsClient) fetchBuiltInLyricsProvider(providerName string, request lyricsProviderSearchRequest) (*LyricsResponse, error, bool) {
+	switch providerName {
+	case LyricsProviderLRCLIB:
+		lyrics, err := c.tryLRCLIB(request.primaryArtist, request.artistName, request.trackName, request.simplifiedTrack, request.durationSec)
+		return lyrics, err, true
+
+	case LyricsProviderNetease:
+		neteaseClient := NewNeteaseClient()
+		lyrics, err := neteaseClient.FetchLyrics(
+			request.trackName,
+			request.primaryArtist,
+			request.durationSec,
+			request.fetchOptions.IncludeTranslationNetease,
+			request.fetchOptions.IncludeRomanizationNetease,
+		)
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.primaryArtist != request.artistName {
+			lyrics, err = neteaseClient.FetchLyrics(
+				request.trackName,
+				request.artistName,
+				request.durationSec,
+				request.fetchOptions.IncludeTranslationNetease,
+				request.fetchOptions.IncludeRomanizationNetease,
+			)
+		}
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.simplifiedTrack != request.trackName {
+			lyrics, err = neteaseClient.FetchLyrics(
+				request.simplifiedTrack,
+				request.primaryArtist,
+				request.durationSec,
+				request.fetchOptions.IncludeTranslationNetease,
+				request.fetchOptions.IncludeRomanizationNetease,
+			)
+		}
+		return lyrics, err, true
+
+	case LyricsProviderMusixmatch:
+		musixmatchClient := NewMusixmatchClient()
+		lyrics, err := musixmatchClient.FetchLyrics(
+			request.trackName,
+			request.primaryArtist,
+			request.durationSec,
+			request.fetchOptions.MusixmatchLanguage,
+		)
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.primaryArtist != request.artistName {
+			lyrics, err = musixmatchClient.FetchLyrics(
+				request.trackName,
+				request.artistName,
+				request.durationSec,
+				request.fetchOptions.MusixmatchLanguage,
+			)
+		}
+		return lyrics, err, true
+
+	case LyricsProviderAppleMusic:
+		appleClient := NewAppleMusicClient()
+		lyrics, err := appleClient.FetchLyrics(request.trackName, request.primaryArtist, request.durationSec, request.fetchOptions.MultiPersonWordByWord, request.fetchOptions.AppleElrcWordSync)
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.primaryArtist != request.artistName {
+			lyrics, err = appleClient.FetchLyrics(request.trackName, request.artistName, request.durationSec, request.fetchOptions.MultiPersonWordByWord, request.fetchOptions.AppleElrcWordSync)
+		}
+		return lyrics, err, true
+
+	case LyricsProviderQQMusic:
+		qqClient := NewQQMusicClient()
+		lyrics, err := qqClient.FetchLyrics(request.trackName, request.primaryArtist, request.durationSec, request.fetchOptions.MultiPersonWordByWord)
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.primaryArtist != request.artistName {
+			lyrics, err = qqClient.FetchLyrics(request.trackName, request.artistName, request.durationSec, request.fetchOptions.MultiPersonWordByWord)
+		}
+		return lyrics, err, true
+
+	case LyricsProviderSpotify:
+		spotifyClient := NewSpotifyLyricsClient()
+		lyrics, err := spotifyClient.FetchLyrics(request.spotifyID, request.trackName, request.primaryArtist, request.durationSec)
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.primaryArtist != request.artistName {
+			lyrics, err = spotifyClient.FetchLyrics(request.spotifyID, request.trackName, request.artistName, request.durationSec)
+		}
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.simplifiedTrack != request.trackName {
+			lyrics, err = spotifyClient.FetchLyrics("", request.simplifiedTrack, request.primaryArtist, request.durationSec)
+		}
+		return lyrics, err, true
+
+	case LyricsProviderDeezer:
+		deezerClient := NewDeezerLyricsClient()
+		lyrics, err := deezerClient.FetchLyrics(request.spotifyID, request.trackName, request.primaryArtist, request.durationSec)
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.primaryArtist != request.artistName {
+			lyrics, err = deezerClient.FetchLyrics(request.spotifyID, request.trackName, request.artistName, request.durationSec)
+		}
+		return lyrics, err, true
+
+	case LyricsProviderYouTube:
+		youtubeClient := NewYouTubeLyricsClient()
+		lyrics, err := youtubeClient.FetchLyrics(request.trackName, request.primaryArtist, request.durationSec)
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.primaryArtist != request.artistName {
+			lyrics, err = youtubeClient.FetchLyrics(request.trackName, request.artistName, request.durationSec)
+		}
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.simplifiedTrack != request.trackName {
+			lyrics, err = youtubeClient.FetchLyrics(request.simplifiedTrack, request.primaryArtist, request.durationSec)
+		}
+		return lyrics, err, true
+
+	case LyricsProviderKugou:
+		kugouClient := NewKugouLyricsClient()
+		lyrics, err := kugouClient.FetchLyrics(request.trackName, request.primaryArtist, request.durationSec)
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.primaryArtist != request.artistName {
+			lyrics, err = kugouClient.FetchLyrics(request.trackName, request.artistName, request.durationSec)
+		}
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.simplifiedTrack != request.trackName {
+			lyrics, err = kugouClient.FetchLyrics(request.simplifiedTrack, request.primaryArtist, request.durationSec)
+		}
+		return lyrics, err, true
+
+	case LyricsProviderGenius:
+		geniusClient := NewGeniusLyricsClient()
+		lyrics, err := geniusClient.FetchLyrics(request.trackName, request.primaryArtist, request.durationSec)
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.primaryArtist != request.artistName {
+			lyrics, err = geniusClient.FetchLyrics(request.trackName, request.artistName, request.durationSec)
+		}
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.simplifiedTrack != request.trackName {
+			lyrics, err = geniusClient.FetchLyrics(request.simplifiedTrack, request.primaryArtist, request.durationSec)
+		}
+		return lyrics, err, true
+
+	case LyricsProviderLyricsPlus:
+		lyricsPlusClient := NewLyricsPlusClient()
+		lyrics, err := lyricsPlusClient.FetchLyrics(
+			request.trackName,
+			request.primaryArtist,
+			"",
+			request.durationSec,
+			request.fetchOptions.MultiPersonWordByWord,
+			request.fetchOptions.AppleElrcWordSync,
+		)
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.primaryArtist != request.artistName {
+			lyrics, err = lyricsPlusClient.FetchLyrics(
+				request.trackName,
+				request.artistName,
+				"",
+				request.durationSec,
+				request.fetchOptions.MultiPersonWordByWord,
+				request.fetchOptions.AppleElrcWordSync,
+			)
+		}
+		if err != nil && !isLyricsProviderUnavailableError(err) && request.simplifiedTrack != request.trackName {
+			lyrics, err = lyricsPlusClient.FetchLyrics(
+				request.simplifiedTrack,
+				request.primaryArtist,
+				"",
+				request.durationSec,
+				request.fetchOptions.MultiPersonWordByWord,
+				request.fetchOptions.AppleElrcWordSync,
+			)
+		}
+		return lyrics, err, true
+	default:
+		return nil, fmt.Errorf("unknown provider: %s", providerName), false
+	}
+}
+
 func (c *LyricsClient) tryLRCLIB(primaryArtist, artistName, trackName, simplifiedTrack string, durationSec float64) (*LyricsResponse, error) {
 	var lyrics *LyricsResponse
 	var err error
@@ -640,6 +1000,9 @@ func (c *LyricsClient) tryLRCLIB(primaryArtist, artistName, trackName, simplifie
 		lyrics.Source = "LRCLIB"
 		return lyrics, nil
 	}
+	if isLyricsProviderUnavailableError(err) {
+		return nil, err
+	}
 
 	if primaryArtist != artistName {
 		lyrics, err = c.FetchLyricsWithMetadata(artistName, trackName)
@@ -647,6 +1010,9 @@ func (c *LyricsClient) tryLRCLIB(primaryArtist, artistName, trackName, simplifie
 			lyrics.Source = "LRCLIB"
 			return lyrics, nil
 		}
+		if isLyricsProviderUnavailableError(err) {
+			return nil, err
+		}
 	}
 
 	if simplifiedTrack != trackName {
@@ -655,6 +1021,9 @@ func (c *LyricsClient) tryLRCLIB(primaryArtist, artistName, trackName, simplifie
 			lyrics.Source = "LRCLIB (simplified)"
 			return lyrics, nil
 		}
+		if isLyricsProviderUnavailableError(err) {
+			return nil, err
+		}
 	}
 
 	query := primaryArtist + " " + trackName
@@ -663,6 +1032,9 @@ func (c *LyricsClient) tryLRCLIB(primaryArtist, artistName, trackName, simplifie
 		lyrics.Source = "LRCLIB Search"
 		return lyrics, nil
 	}
+	if isLyricsProviderUnavailableError(err) {
+		return nil, err
+	}
 
 	if simplifiedTrack != trackName {
 		query = primaryArtist + " " + simplifiedTrack
@@ -671,6 +1043,9 @@ func (c *LyricsClient) tryLRCLIB(primaryArtist, artistName, trackName, simplifie
 			lyrics.Source = "LRCLIB Search (simplified)"
 			return lyrics, nil
 		}
+		if isLyricsProviderUnavailableError(err) {
+			return nil, err
+		}
 	}
 
 	return nil, fmt.Errorf("LRCLIB: no lyrics found")
@@ -814,6 +1189,18 @@ func detectLyricsErrorPayload(raw string) (string, bool) {
 	if success, ok := payload["success"].(bool); ok && !success && !hasLyricsKey {
 		return "request unsuccessful", true
 	}
+	if isError, ok := payload["isError"].(bool); ok && isError && !hasLyricsKey {
+		return "request unsuccessful", true
+	}
+	if code, ok := payload["code"].(float64); ok && code != 0 && code != 200 && !hasLyricsKey {
+		if msg, ok := payload["message"].(string); ok && strings.TrimSpace(msg) != "" {
+			return strings.TrimSpace(msg), true
+		}
+		if msg, ok := payload["msg"].(string); ok && strings.TrimSpace(msg) != "" {
+			return strings.TrimSpace(msg), true
+		}
+		return fmt.Sprintf("unexpected response code %.0f", code), true
+	}
 
 	return "", false
 }
@@ -843,6 +1230,41 @@ func msToLRCTimestampInline(ms int64) string {
 	return fmt.Sprintf("%02d:%02d.%02d", minutes, seconds, centiseconds)
 }
 
+// extractLyricsSourceFromLRC reads the provider recorded in the LRC [by:] tag,
+// e.g. "[by:SpotiFLAC-Mobile (source: LRCLIB)]". Returns "" when absent.
+const lrcSourceMarker = "(source: "
+
+func lyricsSourceUsesPaxsenix(source string) bool {
+	s := strings.ToLower(strings.TrimSpace(source))
+	if s == "" {
+		return false
+	}
+	if strings.HasPrefix(s, "lrclib") ||
+		strings.HasPrefix(s, "extension:") ||
+		strings.HasPrefix(s, "heuristic") {
+		return false
+	}
+	return true
+}
+
+func extractLyricsSourceFromLRC(lrc string) string {
+	for _, line := range strings.Split(lrc, "\n") {
+		trimmed := strings.TrimSpace(line)
+		if !strings.HasPrefix(strings.ToLower(trimmed), "[by:") {
+			continue
+		}
+		idx := strings.Index(trimmed, lrcSourceMarker)
+		if idx < 0 {
+			return ""
+		}
+		rest := strings.TrimSpace(trimmed[idx+len(lrcSourceMarker):])
+		rest = strings.TrimSuffix(rest, "]")
+		rest = strings.TrimSuffix(rest, ")")
+		return strings.TrimSpace(rest)
+	}
+	return ""
+}
+
 func convertToLRCWithMetadata(lyrics *LyricsResponse, trackName, artistName string) string {
 	if lyrics == nil || len(lyrics.Lines) == 0 {
 		return ""
@@ -852,7 +1274,21 @@ func convertToLRCWithMetadata(lyrics *LyricsResponse, trackName, artistName stri
 
 	builder.WriteString(fmt.Sprintf("[ti:%s]\n", trackName))
 	builder.WriteString(fmt.Sprintf("[ar:%s]\n", artistName))
-	builder.WriteString("[by:Implemented by SpotiFLAC-Mobile using Paxsenix API]\n")
+	source := strings.TrimSpace(lyrics.Source)
+	if source == "" {
+		source = strings.TrimSpace(lyrics.Provider)
+	}
+	credit := "SpotiFLAC-Mobile"
+	if lyricsSourceUsesPaxsenix(source) {
+		credit = "SpotiFLAC-Mobile via Paxsenix API"
+	}
+	if source == "" {
+		builder.WriteString(fmt.Sprintf("[by:%s]\n", credit))
+	} else {
+		builder.WriteString(
+			fmt.Sprintf("[by:%s %s%s)]\n", credit, lrcSourceMarker, source),
+		)
+	}
 	builder.WriteString("\n")
 
 	if lyrics.SyncType == "LINE_SYNCED" {

go_backend/lyrics_apple.go

@@ -2,6 +2,7 @@ package gobackend
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"math"
@@ -13,6 +14,8 @@ import (
 	"time"
 )
 
+var errAppleMusicUnauthorized = errors.New("apple music catalog search unauthorized")
+
 type AppleMusicClient struct {
 	httpClient *http.Client
 }
@@ -188,7 +191,7 @@ func (c *AppleMusicClient) getAppleMusicToken() (string, error) {
 		return "", fmt.Errorf("failed to read apple music script: %w", err)
 	}
 
-	token := regexp.MustCompile(`eyJh[^"' <]+`).FindString(string(jsBody))
+	token := regexp.MustCompile(`eyJ[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+`).FindString(string(jsBody))
 	if token == "" {
 		return "", fmt.Errorf("apple music token not found")
 	}
@@ -235,7 +238,7 @@ func (c *AppleMusicClient) searchSongWithToken(token, query string) ([]appleMusi
 	defer resp.Body.Close()
 
 	if resp.StatusCode == http.StatusUnauthorized {
-		return nil, fmt.Errorf("apple music catalog search unauthorized")
+		return nil, errAppleMusicUnauthorized
 	}
 	if resp.StatusCode != http.StatusOK {
 		return nil, fmt.Errorf("apple music catalog search returned HTTP %d", resp.StatusCode)
@@ -281,7 +284,7 @@ func (c *AppleMusicClient) SearchSong(trackName, artistName string, durationSec
 	}
 
 	searchResp, err := c.searchSongWithToken(token, strings.TrimSpace(query))
-	if err != nil && strings.Contains(strings.ToLower(err.Error()), "unauthorized") {
+	if errors.Is(err, errAppleMusicUnauthorized) {
 		clearAppleMusicToken()
 		token, tokenErr := c.getAppleMusicToken()
 		if tokenErr != nil {

go_backend/lyrics_lyricsplus.go

@@ -0,0 +1,239 @@
+package gobackend
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// LyricsPlus (KPOE) provider.
+//
+// LyricsPlus aggregates word-by-word ("karaoke") synced lyrics from Apple
+// Music, Musixmatch, Spotify and QQ Music via a community-run backend. It
+// frequently has word-level timing for tracks that other providers only offer
+// line-synced or not at all.
+//
+// API: GET {server}/v2/lyrics/get?title=&artist=&album=&duration=&isrc=
+// The response is the KPOE JSON format which we convert into the same enhanced
+// LRC text the Apple/QQ providers emit, so embedding/export behaves identically.
+
+// Public LyricsPlus / KPOE servers (mirrors). Tried in order with failover.
+// Sourced from the upstream YouLy+ client server list.
+var lyricsPlusServers = []string{
+	"https://lyricsplus.prjktla.workers.dev",
+	"https://lyricsplus.binimum.org",
+}
+
+type LyricsPlusClient struct {
+	httpClient *http.Client
+}
+
+func NewLyricsPlusClient() *LyricsPlusClient {
+	return &LyricsPlusClient{httpClient: NewMetadataHTTPClient(15 * time.Second)}
+}
+
+type lyricsPlusSyllable struct {
+	Text         string  `json:"text"`
+	Time         float64 `json:"time"`     // absolute ms
+	Duration     float64 `json:"duration"` // ms
+	IsBackground bool    `json:"isBackground"`
+}
+
+type lyricsPlusLine struct {
+	Time     float64              `json:"time"`     // absolute ms
+	Duration float64              `json:"duration"` // ms
+	Text     string               `json:"text"`
+	Syllabus []lyricsPlusSyllable `json:"syllabus"`
+}
+
+type lyricsPlusResponse struct {
+	Type   string           `json:"type"` // "Word" | "Line" | "Syllable" | "None"
+	Lyrics []lyricsPlusLine `json:"lyrics"`
+}
+
+// FetchLyrics tries each LyricsPlus server in order until one returns usable
+// lyrics. multiPersonWordByWord and preserveWordTiming mirror the Apple/QQ
+// options so word/background timing is only emitted when the user enabled it.
+func (c *LyricsPlusClient) FetchLyrics(
+	trackName,
+	artistName,
+	isrc string,
+	durationSec float64,
+	multiPersonWordByWord bool,
+	preserveWordTiming bool,
+) (*LyricsResponse, error) {
+	if strings.TrimSpace(trackName) == "" || strings.TrimSpace(artistName) == "" {
+		return nil, fmt.Errorf("lyricsplus: missing track or artist")
+	}
+
+	var lastErr error
+	for _, server := range lyricsPlusServers {
+		lyrics, err := c.fetchFromServer(server, trackName, artistName, isrc, durationSec, multiPersonWordByWord, preserveWordTiming)
+		if err == nil && lyricsHasUsableText(lyrics) {
+			return lyrics, nil
+		}
+		if err != nil {
+			lastErr = err
+			GoLog("[Lyrics] LyricsPlus server %s failed: %v\n", server, err)
+		}
+	}
+
+	if lastErr != nil {
+		return nil, lastErr
+	}
+	return nil, fmt.Errorf("lyricsplus: no lyrics found")
+}
+
+func (c *LyricsPlusClient) fetchFromServer(
+	server,
+	trackName,
+	artistName,
+	isrc string,
+	durationSec float64,
+	multiPersonWordByWord bool,
+	preserveWordTiming bool,
+) (*LyricsResponse, error) {
+	base := strings.TrimRight(strings.TrimSpace(server), "/")
+	if base == "" {
+		return nil, fmt.Errorf("empty server")
+	}
+
+	params := url.Values{}
+	params.Set("title", trackName)
+	params.Set("artist", artistName)
+	if durationSec > 0 {
+		params.Set("duration", strconv.FormatFloat(durationSec, 'f', 3, 64))
+	}
+	if strings.TrimSpace(isrc) != "" {
+		params.Set("isrc", strings.TrimSpace(isrc))
+	}
+
+	fullURL := base + "/v2/lyrics/get?" + params.Encode()
+
+	req, err := http.NewRequest("GET", fullURL, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+	req.Header.Set("Accept", "application/json")
+	req.Header.Set("User-Agent", appUserAgent())
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode == http.StatusNotFound {
+		// Retry without the ISRC filter, which can be too strict.
+		if strings.TrimSpace(isrc) != "" {
+			return c.fetchFromServer(server, trackName, artistName, "", durationSec, multiPersonWordByWord, preserveWordTiming)
+		}
+		return nil, fmt.Errorf("lyrics not found")
+	}
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("HTTP %d", resp.StatusCode)
+	}
+
+	var payload lyricsPlusResponse
+	if err := json.NewDecoder(resp.Body).Decode(&payload); err != nil {
+		return nil, fmt.Errorf("failed to decode lyricsplus response: %w", err)
+	}
+	if len(payload.Lyrics) == 0 {
+		return nil, fmt.Errorf("lyricsplus returned no lines")
+	}
+
+	lrcText := buildLyricsPlusLRC(&payload, multiPersonWordByWord, preserveWordTiming)
+	if strings.TrimSpace(lrcText) == "" {
+		return nil, fmt.Errorf("lyricsplus produced empty lyrics")
+	}
+
+	lyrics := lyricsResponseFromText(lrcText, "LyricsPlus")
+	return lyrics, nil
+}
+
+// buildLyricsPlusLRC converts the KPOE JSON into enhanced LRC text. When word
+// timing is available and enabled, each syllable is emitted as an inline
+// <mm:ss.xx> tag (matching the Apple/QQ output); otherwise a line-synced LRC
+// is produced from the full line text.
+func buildLyricsPlusLRC(resp *lyricsPlusResponse, multiPersonWordByWord bool, preserveWordTiming bool) string {
+	isWordType := strings.EqualFold(resp.Type, "Word") || strings.EqualFold(resp.Type, "Syllable")
+
+	var sb strings.Builder
+	first := true
+	for _, line := range resp.Lyrics {
+		lineText := line.Text
+		hasSyllables := len(line.Syllabus) > 0
+
+		timestamp := msToLRCTimestamp(int64(line.Time))
+
+		if isWordType && preserveWordTiming && hasSyllables {
+			mainSyllables := make([]lyricsPlusSyllable, 0, len(line.Syllabus))
+			bgSyllables := make([]lyricsPlusSyllable, 0)
+			for _, syl := range line.Syllabus {
+				if syl.IsBackground {
+					bgSyllables = append(bgSyllables, syl)
+				} else {
+					mainSyllables = append(mainSyllables, syl)
+				}
+			}
+			if len(mainSyllables) == 0 {
+				mainSyllables = line.Syllabus
+				bgSyllables = nil
+			}
+
+			if !first {
+				sb.WriteString("\n")
+			}
+			first = false
+
+			sb.WriteString(timestamp)
+			appendLyricsPlusSyllables(&sb, mainSyllables)
+
+			if multiPersonWordByWord && len(bgSyllables) > 0 {
+				sb.WriteString("\n[bg:")
+				appendLyricsPlusSyllables(&sb, bgSyllables)
+				sb.WriteString("]")
+			}
+			continue
+		}
+
+		// Line-synced fallback. Reconstruct text from syllables if needed.
+		if strings.TrimSpace(lineText) == "" && hasSyllables {
+			var lineBuilder strings.Builder
+			for _, syl := range line.Syllabus {
+				lineBuilder.WriteString(syl.Text)
+			}
+			lineText = lineBuilder.String()
+		}
+
+		lineText = strings.TrimSpace(lineText)
+		if lineText == "" {
+			continue
+		}
+
+		if !first {
+			sb.WriteString("\n")
+		}
+		first = false
+
+		sb.WriteString(timestamp)
+		sb.WriteString(lineText)
+	}
+
+	return strings.TrimSpace(sb.String())
+}
+
+// appendLyricsPlusSyllables writes each syllable as "<mm:ss.xx>text". KPOE
+// already embeds spacing inside the syllable text, so no extra spaces are added.
+func appendLyricsPlusSyllables(sb *strings.Builder, syllables []lyricsPlusSyllable) {
+	for _, syl := range syllables {
+		sb.WriteString("<")
+		sb.WriteString(msToLRCTimestampInline(int64(syl.Time)))
+		sb.WriteString(">")
+		sb.WriteString(syl.Text)
+	}
+}

go_backend/lyrics_netease.go

@@ -24,7 +24,9 @@ type neteaseSearchResponse struct {
 		} `json:"songs"`
 		SongCount int `json:"songCount"`
 	} `json:"result"`
-	Code int `json:"code"`
+	Code    int    `json:"code"`
+	Message string `json:"message"`
+	Msg     string `json:"msg"`
 }
 
 type neteaseLyricsResponse struct {
@@ -87,6 +89,17 @@ func (c *NeteaseClient) SearchSong(trackName, artistName string) (int64, error)
 		return 0, fmt.Errorf("failed to decode netease search: %w", err)
 	}
 
+	if searchResp.Code != 0 && searchResp.Code != 200 {
+		message := strings.TrimSpace(searchResp.Message)
+		if message == "" {
+			message = strings.TrimSpace(searchResp.Msg)
+		}
+		if message == "" {
+			message = "unexpected response code"
+		}
+		return 0, fmt.Errorf("netease search unavailable: code %d: %s", searchResp.Code, message)
+	}
+
 	if searchResp.Result.SongCount == 0 || len(searchResp.Result.Songs) == 0 {
 		return 0, fmt.Errorf("no songs found on netease")
 	}

go_backend/lyrics_paxsenix.go

@@ -463,7 +463,7 @@ func (c *GeniusLyricsClient) SearchSong(trackName, artistName string, durationSe
 
 	params := url.Values{}
 	params.Set("q", query)
-	params.Set("per_page", "10")
+	params.Set("per_page", "5")
 	raw, err := fetchPaxsenixBody(c.httpClient, "https://genius.com/api/search/multi", params)
 	if err != nil {
 		return "", fmt.Errorf("genius search failed: %w", err)

go_backend/lyrics_supplement_test.go

@@ -1,6 +1,7 @@
 package gobackend
 
 import (
+	"errors"
 	"io"
 	"net/http"
 	"path/filepath"
@@ -54,6 +55,15 @@ func TestLyricsCacheParsingAndLRCLibClient(t *testing.T) {
 	if msg, ok := detectLyricsErrorPayload(`{"success":false,"message":"nope"}`); !ok || msg != "nope" {
 		t.Fatalf("error payload = %q/%v", msg, ok)
 	}
+	if msg, ok := detectLyricsErrorPayload(`{"isError":true,"error":"Missing required parameters"}`); !ok || msg != "Missing required parameters" {
+		t.Fatalf("isError payload = %q/%v", msg, ok)
+	}
+	if msg, ok := detectLyricsErrorPayload(`{"code":405,"message":"rate limited"}`); !ok || msg != "rate limited" {
+		t.Fatalf("coded error payload = %q/%v", msg, ok)
+	}
+	if !isLyricsProviderUnavailableError(errors.New("rate limit")) {
+		t.Fatal("expected rate-limit errors to mark provider unavailable")
+	}
 	if lrcTimestampToMs("01", "02", "345") != 62345 || msToLRCTimestamp(62340) != "[01:02.34]" {
 		t.Fatal("unexpected LRC timestamp conversion")
 	}
@@ -130,9 +140,120 @@ func TestLyricsCacheParsingAndLRCLibClient(t *testing.T) {
 	}
 }
 
+func TestLyricsProviderHealthSkipsUnavailableProvider(t *testing.T) {
+	SetLyricsProviderOrder([]string{LyricsProviderLRCLIB})
+	defer SetLyricsProviderOrder(nil)
+	globalLyricsCache.ClearAll()
+	clearLyricsProviderHealth()
+	defer clearLyricsProviderHealth()
+
+	calls := 0
+	downClient := &LyricsClient{httpClient: &http.Client{Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
+		calls++
+		return &http.Response{StatusCode: 503, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(`service unavailable`)), Request: req}, nil
+	})}}
+
+	if lyrics, err := downClient.FetchLyricsAllSources("", "Down Song", "Artist", 180); err == nil || lyrics != nil {
+		t.Fatalf("expected unavailable provider error, got %#v/%v", lyrics, err)
+	}
+	if calls != 1 {
+		t.Fatalf("expected one HTTP call before cooldown, got %d", calls)
+	}
+	if skip, _, _ := shouldSkipLyricsProvider(LyricsProviderLRCLIB); !skip {
+		t.Fatal("expected LRCLIB to be marked unavailable")
+	}
+	if lyrics, err := downClient.FetchLyricsAllSources("", "Another Song", "Artist", 180); err == nil || lyrics != nil {
+		t.Fatalf("expected skipped provider error, got %#v/%v", lyrics, err)
+	}
+	if calls != 1 {
+		t.Fatalf("provider was called while in cooldown, calls=%d", calls)
+	}
+
+	clearLyricsProviderHealth()
+	globalLyricsCache.ClearAll()
+	notFoundCalls := 0
+	notFoundClient := &LyricsClient{httpClient: &http.Client{Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
+		notFoundCalls++
+		switch req.URL.Path {
+		case "/api/get":
+			return &http.Response{StatusCode: 404, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(`{}`)), Request: req}, nil
+		case "/api/search":
+			return &http.Response{StatusCode: 200, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(`[]`)), Request: req}, nil
+		default:
+			return &http.Response{StatusCode: 404, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(`{}`)), Request: req}, nil
+		}
+	})}}
+
+	if lyrics, err := notFoundClient.FetchLyricsAllSources("", "missing song", "Artist", 180); err == nil || lyrics != nil {
+		t.Fatalf("expected not found error, got %#v/%v", lyrics, err)
+	}
+	if skip, _, _ := shouldSkipLyricsProvider(LyricsProviderLRCLIB); skip {
+		t.Fatal("not-found result must not mark provider unavailable")
+	}
+	if lyrics, err := notFoundClient.FetchLyricsAllSources("", "missing song 2", "Artist", 180); err == nil || lyrics != nil {
+		t.Fatalf("expected second not found error, got %#v/%v", lyrics, err)
+	}
+	if notFoundCalls != 4 {
+		t.Fatalf("expected not-found provider to be retried, calls=%d", notFoundCalls)
+	}
+}
+
+func TestConcurrentLyricsProvidersReturnFastFallback(t *testing.T) {
+	clearLyricsProviderHealth()
+	defer clearLyricsProviderHealth()
+
+	start := time.Now()
+	lyrics, err := fetchBuiltInLyricsProviders(
+		[]string{LyricsProviderLRCLIB, LyricsProviderAppleMusic},
+		lyricsProviderSearchRequest{},
+		func(providerName string, _ lyricsProviderSearchRequest) (*LyricsResponse, error, bool) {
+			if providerName == LyricsProviderLRCLIB {
+				time.Sleep(lyricsProviderPriorityGrace + 800*time.Millisecond)
+				return &LyricsResponse{Provider: "LRCLIB", PlainLyrics: "slow"}, nil, true
+			}
+			return &LyricsResponse{Provider: "Apple Music", PlainLyrics: "fast"}, nil, true
+		},
+	)
+	if err != nil {
+		t.Fatalf("concurrent providers returned error: %v", err)
+	}
+	if lyrics == nil || lyrics.Provider != "Apple Music" {
+		t.Fatalf("expected fast fallback lyrics, got %#v", lyrics)
+	}
+	if elapsed := time.Since(start); elapsed >= lyricsProviderPriorityGrace+700*time.Millisecond {
+		t.Fatalf("fallback waited too long: %s", elapsed)
+	}
+}
+
+func TestConcurrentLyricsProvidersPreferEarlierProviderWithinGrace(t *testing.T) {
+	clearLyricsProviderHealth()
+	defer clearLyricsProviderHealth()
+
+	lyrics, err := fetchBuiltInLyricsProviders(
+		[]string{LyricsProviderLRCLIB, LyricsProviderAppleMusic},
+		lyricsProviderSearchRequest{},
+		func(providerName string, _ lyricsProviderSearchRequest) (*LyricsResponse, error, bool) {
+			if providerName == LyricsProviderLRCLIB {
+				time.Sleep(50 * time.Millisecond)
+				return &LyricsResponse{Provider: "LRCLIB", PlainLyrics: "preferred"}, nil, true
+			}
+			return &LyricsResponse{Provider: "Apple Music", PlainLyrics: "fast"}, nil, true
+		},
+	)
+	if err != nil {
+		t.Fatalf("concurrent providers returned error: %v", err)
+	}
+	if lyrics == nil || lyrics.Provider != "LRCLIB" {
+		t.Fatalf("expected preferred provider lyrics, got %#v", lyrics)
+	}
+}
+
 func TestExternalLyricsProvidersWithFakeHTTP(t *testing.T) {
 	clearAppleMusicToken()
 	defer clearAppleMusicToken()
+	if len(lyricsPlusServers) == 0 || lyricsPlusServers[0] != "https://lyricsplus.prjktla.workers.dev" {
+		t.Fatalf("unexpected LyricsPlus server order = %#v", lyricsPlusServers)
+	}
 
 	paxJSON := `{"type":"Syllable","content":[{"timestamp":1000,"oppositeTurn":true,"background":true,"text":[{"text":"Hel","part":true,"timestamp":1000},{"text":"lo","part":false,"timestamp":1200,"endtime":1500}],"backgroundText":[{"text":"bg","part":false,"timestamp":900}]}]}`
 	apple := &AppleMusicClient{httpClient: &http.Client{Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
@@ -140,7 +261,7 @@ func TestExternalLyricsProvidersWithFakeHTTP(t *testing.T) {
 		case req.URL.Host == "beta.music.apple.com" && (req.URL.Path == "" || req.URL.Path == "/"):
 			return &http.Response{StatusCode: 200, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(`<script src="/assets/index~test.js"></script>`)), Request: req}, nil
 		case req.URL.Host == "beta.music.apple.com" && req.URL.Path == "/assets/index~test.js":
-			return &http.Response{StatusCode: 200, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(`const token="eyJhbGci.test";`)), Request: req}, nil
+			return &http.Response{StatusCode: 200, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(`const token="eyJ0eXAiOiJKV1Q.eyJpc3MiOiJ0ZXN0.c2ln";`)), Request: req}, nil
 		case req.URL.Host == "amp-api.music.apple.com" && strings.Contains(req.URL.Path, "/v1/catalog/us/search"):
 			return &http.Response{StatusCode: 200, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(`{"results":{"songs":{"data":[{"id":"apple-2"},{"id":"apple-1"}]}},"resources":{"songs":{"apple-2":{"attributes":{"name":"Other","artistName":"Other","durationInMillis":1000}},"apple-1":{"attributes":{"name":"Song","artistName":"Artist","albumName":"Album","durationInMillis":180000}}}}}`)), Request: req}, nil
 		case strings.Contains(req.URL.Path, "/apple-music/lyrics"):
@@ -236,6 +357,12 @@ func TestExternalLyricsProvidersWithFakeHTTP(t *testing.T) {
 	if _, err := netease.SearchSong("", ""); err == nil {
 		t.Fatal("expected empty netease search error")
 	}
+	rateLimitedNetease := &NeteaseClient{httpClient: &http.Client{Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
+		return &http.Response{StatusCode: 200, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(`{"msg":"操作频繁，请稍候再试","code":405,"message":"操作频繁，请稍候再试"}`)), Request: req}, nil
+	})}}
+	if _, err := rateLimitedNetease.SearchSong("Song", "Artist"); err == nil || !isLyricsProviderUnavailableError(err) {
+		t.Fatalf("expected unavailable netease rate-limit error, got %v", err)
+	}
 
 	qq := &QQMusicClient{httpClient: &http.Client{Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
 		if req.Method != http.MethodPost {
@@ -311,6 +438,9 @@ func TestExternalLyricsProvidersWithFakeHTTP(t *testing.T) {
 	genius := &GeniusLyricsClient{httpClient: &http.Client{Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
 		switch {
 		case strings.Contains(req.URL.Path, "/api/search/multi"):
+			if got := req.URL.Query().Get("per_page"); got != "5" {
+				t.Fatalf("genius per_page = %q", got)
+			}
 			return &http.Response{StatusCode: 200, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(`{"response":{"sections":[{"hits":[{"type":"song","result":{"title":"Song","primary_artist_names":"Artist","url":"https://genius.com/artist-song-lyrics"}}]}]}}`)), Request: req}, nil
 		case strings.Contains(req.URL.Path, "/genius/lyrics"):
 			return &http.Response{StatusCode: 200, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(`{"error":false,"lyrics":"Genius line"}`)), Request: req}, nil

go_backend/m4a_freeform_write_test.go

@@ -0,0 +1,68 @@
+package gobackend
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestEditM4AFreeformTextWritesISRCAndLabel(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "track.m4a")
+
+	ilst := buildM4ATextTag("\xa9nam", "Title")
+	if err := os.WriteFile(path, buildM4AFileWithIlst(ilst, true), 0600); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := EditM4AFreeformText(path, map[string]string{
+		"isrc":  "USRC17607839",
+		"label": "Some Label",
+	}); err != nil {
+		t.Fatalf("EditM4AFreeformText: %v", err)
+	}
+
+	meta, err := ReadM4ATags(path)
+	if err != nil {
+		t.Fatalf("ReadM4ATags: %v", err)
+	}
+	if meta.ISRC != "USRC17607839" {
+		t.Fatalf("ISRC = %q, want USRC17607839", meta.ISRC)
+	}
+	if meta.Label != "Some Label" {
+		t.Fatalf("Label = %q, want Some Label", meta.Label)
+	}
+	if meta.Title != "Title" {
+		t.Fatalf("Title = %q, want Title (existing tag must survive)", meta.Title)
+	}
+}
+
+func TestEditM4AFreeformTextReplacesExisting(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "track.m4a")
+
+	ilst := buildM4ATextTag("\xa9nam", "Title")
+	ilst = append(ilst, buildM4AFreeformAtom("ISRC", "OLDISRC00001")...)
+	ilst = append(ilst, buildM4AFreeformAtom("LABEL", "Old Label")...)
+	if err := os.WriteFile(path, buildM4AFileWithIlst(ilst, true), 0600); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := EditM4AFreeformText(path, map[string]string{
+		"isrc":  "NEWISRC00002",
+		"label": "",
+	}); err != nil {
+		t.Fatalf("EditM4AFreeformText: %v", err)
+	}
+
+	meta, err := ReadM4ATags(path)
+	if err != nil {
+		t.Fatalf("ReadM4ATags: %v", err)
+	}
+	if meta.ISRC != "NEWISRC00002" {
+		t.Fatalf("ISRC = %q, want NEWISRC00002", meta.ISRC)
+	}
+	if meta.Label != "" {
+		t.Fatalf("Label = %q, want empty (cleared)", meta.Label)
+	}
+}

go_backend/metadata.go

@@ -6,7 +6,7 @@ import (
 	"fmt"
 	stdimage "image"
 	_ "image/gif"
-	_ "image/jpeg"
+	"image/jpeg"
 	_ "image/png"
 	"io"
 	"math"
@@ -71,11 +71,83 @@ func detectCoverMIME(coverPath string, coverData []byte) string {
 	return "image/jpeg"
 }
 
+// maxFlacPictureBytes keeps cover art below the 24-bit length field of a FLAC
+// metadata block; go-flac silently truncates oversized blocks into a corrupt file.
+const maxFlacPictureBytes = 16 * 1000 * 1000
+
+// fitCoverForFlac returns cover bytes that fit inside a FLAC PICTURE block,
+// re-encoding and downscaling when needed. Returns false if the data cannot be
+// decoded as an image.
+func fitCoverForFlac(coverData []byte) ([]byte, bool) {
+	if len(coverData) <= maxFlacPictureBytes {
+		return coverData, true
+	}
+
+	img, _, err := stdimage.Decode(bytes.NewReader(coverData))
+	if err != nil {
+		return nil, false
+	}
+
+	for _, quality := range []int{90, 80, 70, 60} {
+		if encoded, ok := encodeJPEGUnder(img, quality, maxFlacPictureBytes); ok {
+			return encoded, true
+		}
+	}
+
+	for _, maxDim := range []int{1500, 1200, 1000, 800} {
+		scaled := downscaleImage(img, maxDim)
+		if encoded, ok := encodeJPEGUnder(scaled, 85, maxFlacPictureBytes); ok {
+			return encoded, true
+		}
+	}
+
+	return nil, false
+}
+
+func encodeJPEGUnder(img stdimage.Image, quality, limit int) ([]byte, bool) {
+	var buf bytes.Buffer
+	if err := jpeg.Encode(&buf, img, &jpeg.Options{Quality: quality}); err != nil {
+		return nil, false
+	}
+	if buf.Len() > limit {
+		return nil, false
+	}
+	return buf.Bytes(), true
+}
+
+func downscaleImage(img stdimage.Image, maxDim int) stdimage.Image {
+	bounds := img.Bounds()
+	width, height := bounds.Dx(), bounds.Dy()
+	if width <= maxDim && height <= maxDim {
+		return img
+	}
+
+	scale := float64(maxDim) / float64(max(width, height))
+	newWidth := max(1, int(float64(width)*scale))
+	newHeight := max(1, int(float64(height)*scale))
+
+	dst := stdimage.NewRGBA(stdimage.Rect(0, 0, newWidth, newHeight))
+	for y := 0; y < newHeight; y++ {
+		srcY := bounds.Min.Y + int(float64(y)/scale)
+		for x := 0; x < newWidth; x++ {
+			srcX := bounds.Min.X + int(float64(x)/scale)
+			dst.Set(x, y, img.At(srcX, srcY))
+		}
+	}
+	return dst
+}
+
 func buildPictureBlock(coverPath string, coverData []byte) (flac.MetaDataBlock, error) {
 	if len(coverData) == 0 {
 		return flac.MetaDataBlock{}, fmt.Errorf("empty cover data")
 	}
 
+	fitted, ok := fitCoverForFlac(coverData)
+	if !ok {
+		return flac.MetaDataBlock{}, fmt.Errorf("cover too large for FLAC picture block and could not be resized")
+	}
+	coverData = fitted
+
 	mime := detectCoverMIME(coverPath, coverData)
 	picture := &flacpicture.MetadataBlockPicture{
 		PictureType: flacpicture.PictureTypeFrontCover,
@@ -175,10 +247,11 @@ func EmbedMetadata(filePath string, metadata Metadata, coverPath string) error {
 
 				picBlock, err := buildPictureBlock(coverPath, coverData)
 				if err != nil {
-					return fmt.Errorf("failed to create picture block: %w", err)
+					fmt.Printf("[Metadata] Warning: skipping cover art: %v\n", err)
+				} else {
+					f.Meta = append(f.Meta, &picBlock)
+					fmt.Printf("[Metadata] Cover art embedded successfully (%d bytes)\n", len(coverData))
 				}
-				f.Meta = append(f.Meta, &picBlock)
-				fmt.Printf("[Metadata] Cover art embedded successfully (%d bytes)\n", len(coverData))
 			}
 		} else {
 			fmt.Printf("[Metadata] Warning: Cover file does not exist: %s\n", coverPath)
@@ -230,10 +303,11 @@ func EmbedMetadataWithCoverData(filePath string, metadata Metadata, coverData []
 
 		picBlock, err := buildPictureBlock("", coverData)
 		if err != nil {
-			return fmt.Errorf("failed to create picture block: %w", err)
+			fmt.Printf("[Metadata] Warning: skipping cover art: %v\n", err)
+		} else {
+			f.Meta = append(f.Meta, &picBlock)
+			fmt.Printf("[Metadata] Cover art embedded successfully (%d bytes)\n", len(coverData))
 		}
-		f.Meta = append(f.Meta, &picBlock)
-		fmt.Printf("[Metadata] Cover art embedded successfully (%d bytes)\n", len(coverData))
 	}
 
 	return f.Save(filePath)
@@ -906,6 +980,32 @@ func ExtractLyrics(filePath string) (string, error) {
 		return extractLyricsFromSidecarLRC(filePath)
 	}
 
+	if strings.HasSuffix(lower, ".wav") {
+		meta, err := ReadWAVTags(filePath)
+		if err == nil && meta != nil {
+			if strings.TrimSpace(meta.Lyrics) != "" {
+				return meta.Lyrics, nil
+			}
+			if looksLikeEmbeddedLyrics(meta.Comment) {
+				return meta.Comment, nil
+			}
+		}
+		return extractLyricsFromSidecarLRC(filePath)
+	}
+
+	if strings.HasSuffix(lower, ".aiff") || strings.HasSuffix(lower, ".aif") || strings.HasSuffix(lower, ".aifc") {
+		meta, err := ReadAIFFTags(filePath)
+		if err == nil && meta != nil {
+			if strings.TrimSpace(meta.Lyrics) != "" {
+				return meta.Lyrics, nil
+			}
+			if looksLikeEmbeddedLyrics(meta.Comment) {
+				return meta.Comment, nil
+			}
+		}
+		return extractLyricsFromSidecarLRC(filePath)
+	}
+
 	return extractLyricsFromSidecarLRC(filePath)
 }
 
@@ -1097,9 +1197,7 @@ func findM4AIlstAtom(f *os.File, fileSize int64) (atomHeader, error) {
 		udtaBodyStart := udta.offset + udta.headerSize
 		udtaBodySize := udta.size - udta.headerSize
 		if meta, ok2, _ := findAtomInRange(f, udtaBodyStart, udtaBodySize, "meta", fileSize); ok2 {
-			metaBodyStart := meta.offset + meta.headerSize + 4
-			metaBodySize := meta.size - meta.headerSize - 4
-			if ilst, ok3, _ := findAtomInRange(f, metaBodyStart, metaBodySize, "ilst", fileSize); ok3 {
+			if ilst, ok3 := findIlstInMeta(f, meta, fileSize); ok3 {
 				return ilst, nil
 			}
 		}
@@ -1107,9 +1205,7 @@ func findM4AIlstAtom(f *os.File, fileSize int64) (atomHeader, error) {
 
 	// Path 2: moov > meta > ilst (no udta wrapper)
 	if meta, ok, _ := findAtomInRange(f, moovBodyStart, moovBodySize, "meta", fileSize); ok {
-		metaBodyStart := meta.offset + meta.headerSize + 4
-		metaBodySize := meta.size - meta.headerSize - 4
-		if ilst, ok2, _ := findAtomInRange(f, metaBodyStart, metaBodySize, "ilst", fileSize); ok2 {
+		if ilst, ok2 := findIlstInMeta(f, meta, fileSize); ok2 {
 			return ilst, nil
 		}
 	}
@@ -1117,6 +1213,26 @@ func findM4AIlstAtom(f *os.File, fileSize int64) (atomHeader, error) {
 	return atomHeader{}, fmt.Errorf("ilst not found (tried moov>udta>meta>ilst and moov>meta>ilst)")
 }
 
+// findIlstInMeta locates the ilst atom inside a meta atom, handling both
+// layouts: ISO-BMFF (4-byte version/flags before the child atoms, written by
+// FFmpeg's mp4 muxer) and QuickTime (no version/flags, written by the mov muxer
+// used for AC-4 passthrough).
+func findIlstInMeta(f *os.File, meta atomHeader, fileSize int64) (atomHeader, bool) {
+	// ISO-BMFF: skip the 4-byte version/flags that precede the child atoms.
+	isoStart := meta.offset + meta.headerSize + 4
+	isoSize := meta.size - meta.headerSize - 4
+	if ilst, ok, _ := findAtomInRange(f, isoStart, isoSize, "ilst", fileSize); ok {
+		return ilst, true
+	}
+	// QuickTime: child atoms begin immediately after the meta header.
+	qtStart := meta.offset + meta.headerSize
+	qtSize := meta.size - meta.headerSize
+	if ilst, ok, _ := findAtomInRange(f, qtStart, qtSize, "ilst", fileSize); ok {
+		return ilst, true
+	}
+	return atomHeader{}, false
+}
+
 func readM4ADataAtomPayload(f *os.File, dataAtom atomHeader) ([]byte, error) {
 	payloadStart := dataAtom.offset + dataAtom.headerSize + 8
 	payloadLen := dataAtom.size - dataAtom.headerSize - 8
@@ -1254,9 +1370,7 @@ func findM4AMetadataPath(f *os.File, fileSize int64) (m4aMetadataPath, error) {
 		udtaBodyStart := udta.offset + udta.headerSize
 		udtaBodySize := udta.size - udta.headerSize
 		if meta, ok2, _ := findAtomInRange(f, udtaBodyStart, udtaBodySize, "meta", fileSize); ok2 {
-			metaBodyStart := meta.offset + meta.headerSize + 4
-			metaBodySize := meta.size - meta.headerSize - 4
-			if ilst, ok3, _ := findAtomInRange(f, metaBodyStart, metaBodySize, "ilst", fileSize); ok3 {
+			if ilst, ok3 := findIlstInMeta(f, meta, fileSize); ok3 {
 				udtaCopy := udta
 				return m4aMetadataPath{
 					moov: moov,
@@ -1269,9 +1383,7 @@ func findM4AMetadataPath(f *os.File, fileSize int64) (m4aMetadataPath, error) {
 	}
 
 	if meta, ok, _ := findAtomInRange(f, moovBodyStart, moovBodySize, "meta", fileSize); ok {
-		metaBodyStart := meta.offset + meta.headerSize + 4
-		metaBodySize := meta.size - meta.headerSize - 4
-		if ilst, ok2, _ := findAtomInRange(f, metaBodyStart, metaBodySize, "ilst", fileSize); ok2 {
+		if ilst, ok2 := findIlstInMeta(f, meta, fileSize); ok2 {
 			return m4aMetadataPath{
 				moov: moov,
 				meta: meta,
@@ -1406,6 +1518,51 @@ func EditM4AReplayGain(filePath string, fields map[string]string) error {
 		return nil
 	}
 
+	remove := map[string]struct{}{
+		"REPLAYGAIN_TRACK_GAIN": {},
+		"REPLAYGAIN_TRACK_PEAK": {},
+		"REPLAYGAIN_ALBUM_GAIN": {},
+		"REPLAYGAIN_ALBUM_PEAK": {},
+		"ITUNNORM":              {},
+	}
+
+	order := []string{
+		"replaygain_track_gain",
+		"replaygain_track_peak",
+		"replaygain_album_gain",
+		"replaygain_album_peak",
+		"iTunNORM",
+	}
+	tags := make([]m4aFreeformTag, 0, len(order))
+	for _, key := range order {
+		value := strings.TrimSpace(replayGainFields[key])
+		if value == "" {
+			continue
+		}
+		name := key
+		if key != "iTunNORM" {
+			name = strings.ToLower(key)
+		}
+		tags = append(tags, m4aFreeformTag{name: name, value: value})
+	}
+
+	return writeM4AFreeformTags(filePath, remove, tags)
+}
+
+type m4aFreeformTag struct {
+	name  string
+	value string
+}
+
+// writeM4AFreeformTags rewrites the ilst atom in place: it drops every existing
+// freeform ("----") atom whose uppercased name is in `remove`, then appends the
+// supplied tags (empty values are skipped, which effectively clears the field).
+// Atom sizes are fixed up along the ilst -> meta -> udta -> moov chain.
+//
+// FFmpeg's MP4 muxer only writes a fixed set of recognized keys to the ilst, so
+// fields like ISRC and LABEL are silently dropped when written via -metadata.
+// Writing them as iTunes freeform atoms natively is the only way they persist.
+func writeM4AFreeformTags(filePath string, remove map[string]struct{}, tags []m4aFreeformTag) error {
 	f, err := os.Open(filePath)
 	if err != nil {
 		return err
@@ -1419,6 +1576,13 @@ func EditM4AReplayGain(filePath string, fields map[string]string) error {
 
 	path, err := findM4AMetadataPath(f, info.Size())
 	if err != nil {
+		// MOV-style containers (e.g. AC-4 passthrough) store tags as QuickTime
+		// atoms under udta with no iTunes meta>ilst structure. There is nowhere
+		// to write freeform tags, so skip gracefully instead of failing.
+		if strings.Contains(err.Error(), "ilst not found") {
+			GoLog("[Metadata] No iTunes ilst container; skipping freeform tags")
+			return nil
+		}
 		return err
 	}
 
@@ -1430,13 +1594,6 @@ func EditM4AReplayGain(filePath string, fields map[string]string) error {
 	bodyStart := path.ilst.offset + path.ilst.headerSize
 	bodyEnd := path.ilst.offset + path.ilst.size
 	newBody := make([]byte, 0, int(path.ilst.size))
-	targets := map[string]struct{}{
-		"REPLAYGAIN_TRACK_GAIN": {},
-		"REPLAYGAIN_TRACK_PEAK": {},
-		"REPLAYGAIN_ALBUM_GAIN": {},
-		"REPLAYGAIN_ALBUM_PEAK": {},
-		"ITUNNORM":              {},
-	}
 
 	for pos := bodyStart; pos+8 <= bodyEnd; {
 		header, readErr := readAtomHeaderAt(f, pos, info.Size())
@@ -1454,7 +1611,7 @@ func EditM4AReplayGain(filePath string, fields map[string]string) error {
 		if header.typ == "----" {
 			name, _, freeformErr := readM4AFreeformValue(f, header, info.Size())
 			if freeformErr == nil {
-				if _, ok := targets[strings.ToUpper(strings.TrimSpace(name))]; ok {
+				if _, ok := remove[strings.ToUpper(strings.TrimSpace(name))]; ok {
 					keep = false
 				}
 			}
@@ -1466,23 +1623,11 @@ func EditM4AReplayGain(filePath string, fields map[string]string) error {
 		pos += header.size
 	}
 
-	order := []string{
-		"replaygain_track_gain",
-		"replaygain_track_peak",
-		"replaygain_album_gain",
-		"replaygain_album_peak",
-		"iTunNORM",
-	}
-	for _, key := range order {
-		value := strings.TrimSpace(replayGainFields[key])
-		if value == "" {
+	for _, tag := range tags {
+		if strings.TrimSpace(tag.value) == "" {
 			continue
 		}
-		name := key
-		if key != "iTunNORM" {
-			name = strings.ToLower(key)
-		}
-		newBody = append(newBody, buildM4AFreeformAtom(name, value)...)
+		newBody = append(newBody, buildM4AFreeformAtom(tag.name, tag.value)...)
 	}
 
 	newIlst := buildM4AAtom("ilst", newBody)
@@ -1509,6 +1654,32 @@ func EditM4AReplayGain(filePath string, fields map[string]string) error {
 	return os.WriteFile(filePath, updated, 0o644)
 }
 
+// EditM4AFreeformText writes ISRC and label tags into an M4A/MP4 file as iTunes
+// freeform atoms. These keys are not part of FFmpeg's MP4 metadata key set, so
+// they must be written natively for the values to actually persist. An empty
+// value clears the corresponding tag. Other (recognized) tags are left intact.
+func EditM4AFreeformText(filePath string, fields map[string]string) error {
+	_, hasISRC := fields["isrc"]
+	_, hasLabel := fields["label"]
+	if !hasISRC && !hasLabel {
+		return nil
+	}
+
+	remove := map[string]struct{}{}
+	tags := make([]m4aFreeformTag, 0, 2)
+	if hasISRC {
+		remove["ISRC"] = struct{}{}
+		tags = append(tags, m4aFreeformTag{name: "ISRC", value: strings.TrimSpace(fields["isrc"])})
+	}
+	if hasLabel {
+		remove["LABEL"] = struct{}{}
+		remove["ORGANIZATION"] = struct{}{}
+		tags = append(tags, m4aFreeformTag{name: "LABEL", value: strings.TrimSpace(fields["label"])})
+	}
+
+	return writeM4AFreeformTags(filePath, remove, tags)
+}
+
 func extractLyricsFromSidecarLRC(filePath string) (string, error) {
 	ext := filepath.Ext(filePath)
 	base := strings.TrimSuffix(filePath, ext)

go_backend/output_fd.go

@@ -35,7 +35,7 @@ func openOutputForWrite(outputPath string, outputFD int) (*os.File, error) {
 		if err == nil {
 			return file, nil
 		}
-		if strings.Contains(strings.ToLower(err.Error()), "permission denied") {
+		if os.IsPermission(err) {
 			return os.OpenFile(path, os.O_WRONLY, 0)
 		}
 		return nil, err

go_backend/wav_aiff.go

@@ -0,0 +1,959 @@
+package gobackend
+
+// WAV (RIFF) and AIFF/AIFC support: quality probing, tag reading/writing, and
+// cover-art extraction. These containers are not handled by go-flac, so chunks
+// are parsed/written by hand here.
+//
+// Tags are stored as an embedded ID3v2.4 tag (UTF-8): WAV uses a lowercase
+// "id3 " chunk, AIFF uses an uppercase "ID3 " chunk. ID3v2.4 is chosen because
+// the existing ID3 reader (parseID3v23Frames with version=4) reads synchsafe
+// frame sizes and UTF-8 text, so anything we write is read back losslessly.
+//
+// Reading also recognises a WAV "LIST"/"INFO" block as a fallback for files
+// that carry only RIFF INFO tags (common from other taggers).
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"math"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+// WAVQuality / AIFFQuality mirror the other GetXQuality result shapes.
+type WAVQuality struct {
+	SampleRate int
+	BitDepth   int
+	Channels   int
+	Duration   int
+}
+
+const (
+	wavMaxMetaChunk  = 16 * 1024 * 1024 // safety cap for buffering a metadata chunk
+	id3ChunkWAV      = "id3 "
+	id3ChunkAIFF     = "ID3 "
+	wavFormatPCM     = 0x0001
+	wavFormatFloat   = 0x0003
+	wavFormatExtensn = 0xFFFE
+)
+
+func putUint32(dst []byte, le bool, v uint32) {
+	if le {
+		binary.LittleEndian.PutUint32(dst, v)
+	} else {
+		binary.BigEndian.PutUint32(dst, v)
+	}
+}
+
+func readUint32(b []byte, le bool) uint32 {
+	if le {
+		return binary.LittleEndian.Uint32(b)
+	}
+	return binary.BigEndian.Uint32(b)
+}
+
+func synchsafeEncode(n int) []byte {
+	return []byte{
+		byte((n >> 21) & 0x7f),
+		byte((n >> 14) & 0x7f),
+		byte((n >> 7) & 0x7f),
+		byte(n & 0x7f),
+	}
+}
+
+func synchsafeDecode(b []byte) int {
+	if len(b) < 4 {
+		return 0
+	}
+	return int(b[0])<<21 | int(b[1])<<14 | int(b[2])<<7 | int(b[3])
+}
+
+// parseExtendedFloat80 decodes an 80-bit IEEE 754 extended float (used by the
+// AIFF COMM chunk for the sample rate).
+func parseExtendedFloat80(b []byte) float64 {
+	if len(b) < 10 {
+		return 0
+	}
+	sign := 1.0
+	if b[0]&0x80 != 0 {
+		sign = -1.0
+	}
+	exponent := int(b[0]&0x7f)<<8 | int(b[1])
+	var mantissa uint64
+	for i := 2; i < 10; i++ {
+		mantissa = mantissa<<8 | uint64(b[i])
+	}
+	if exponent == 0 && mantissa == 0 {
+		return 0
+	}
+	return sign * float64(mantissa) * math.Pow(2, float64(exponent-16383-63))
+}
+
+type wavProbe struct {
+	sampleRate int
+	bitDepth   int
+	channels   int
+	byteRate   int
+	dataSize   int64
+	id3        []byte
+	info       map[string]string
+}
+
+// streamProbeWAV walks the top-level RIFF chunks, buffering only the small
+// metadata chunks (fmt/id3/LIST) and skipping the large data chunk.
+func streamProbeWAV(f *os.File) (*wavProbe, error) {
+	header := make([]byte, 12)
+	if _, err := io.ReadFull(f, header); err != nil {
+		return nil, err
+	}
+	if string(header[0:4]) != "RIFF" || string(header[8:12]) != "WAVE" {
+		return nil, fmt.Errorf("not a WAVE file")
+	}
+
+	p := &wavProbe{info: map[string]string{}}
+	hdr := make([]byte, 8)
+	for {
+		if _, err := io.ReadFull(f, hdr); err != nil {
+			break
+		}
+		id := string(hdr[0:4])
+		size := readUint32(hdr[4:8], true)
+		pad := int64(size) & 1
+
+		switch id {
+		case "fmt ":
+			buf := make([]byte, size)
+			if _, err := io.ReadFull(f, buf); err != nil {
+				return p, nil
+			}
+			if len(buf) >= 16 {
+				format := binary.LittleEndian.Uint16(buf[0:2])
+				p.channels = int(binary.LittleEndian.Uint16(buf[2:4]))
+				p.sampleRate = int(binary.LittleEndian.Uint32(buf[4:8]))
+				p.byteRate = int(binary.LittleEndian.Uint32(buf[8:12]))
+				p.bitDepth = int(binary.LittleEndian.Uint16(buf[14:16]))
+				if format == wavFormatExtensn && len(buf) >= 26 {
+					// Valid bits per sample lives in the extension; the real
+					// PCM format tag is in the GUID, but bitDepth from the
+					// container field is sufficient for display.
+					if vb := int(binary.LittleEndian.Uint16(buf[18:20])); vb > 0 {
+						p.bitDepth = vb
+					}
+				}
+			}
+			if pad == 1 {
+				f.Seek(pad, io.SeekCurrent)
+			}
+		case "data":
+			p.dataSize = int64(size)
+			f.Seek(int64(size)+pad, io.SeekCurrent)
+		case id3ChunkWAV, "ID3 ":
+			if size > 0 && size <= wavMaxMetaChunk {
+				buf := make([]byte, size)
+				if _, err := io.ReadFull(f, buf); err == nil {
+					p.id3 = buf
+				}
+				if pad == 1 {
+					f.Seek(pad, io.SeekCurrent)
+				}
+			} else {
+				f.Seek(int64(size)+pad, io.SeekCurrent)
+			}
+		case "LIST":
+			if size > 0 && size <= wavMaxMetaChunk {
+				buf := make([]byte, size)
+				if _, err := io.ReadFull(f, buf); err == nil {
+					parseRIFFInfo(buf, p.info)
+				}
+				if pad == 1 {
+					f.Seek(pad, io.SeekCurrent)
+				}
+			} else {
+				f.Seek(int64(size)+pad, io.SeekCurrent)
+			}
+		default:
+			f.Seek(int64(size)+pad, io.SeekCurrent)
+		}
+	}
+	return p, nil
+}
+
+// parseRIFFInfo reads a LIST/INFO block ("INFO" + sub-chunks like INAM, IART).
+func parseRIFFInfo(buf []byte, out map[string]string) {
+	if len(buf) < 4 || string(buf[0:4]) != "INFO" {
+		return
+	}
+	pos := 4
+	for pos+8 <= len(buf) {
+		id := string(buf[pos : pos+4])
+		size := int(binary.LittleEndian.Uint32(buf[pos+4 : pos+8]))
+		pos += 8
+		if size <= 0 || pos+size > len(buf) {
+			break
+		}
+		val := strings.TrimRight(string(buf[pos:pos+size]), "\x00")
+		out[id] = strings.TrimSpace(val)
+		pos += size
+		if size&1 == 1 {
+			pos++
+		}
+	}
+}
+
+func wavMetadataFromProbe(p *wavProbe) *AudioMetadata {
+	if p == nil {
+		return nil
+	}
+	if len(p.id3) > 0 {
+		if meta, err := readID3v2FromBytes(p.id3); err == nil && meta != nil &&
+			(meta.Title != "" || meta.Artist != "" || meta.Album != "") {
+			return meta
+		}
+	}
+	if len(p.info) > 0 {
+		meta := &AudioMetadata{
+			Title:     p.info["INAM"],
+			Artist:    p.info["IART"],
+			Album:     p.info["IPRD"],
+			Genre:     cleanGenre(p.info["IGNR"]),
+			Date:      p.info["ICRD"],
+			Comment:   p.info["ICMT"],
+			Copyright: p.info["ICOP"],
+			Composer:  p.info["IMUS"],
+		}
+		if n, err := strconv.Atoi(strings.TrimSpace(p.info["ITRK"])); err == nil {
+			meta.TrackNumber = n
+		}
+		if meta.Date != "" && len(meta.Date) >= 4 {
+			meta.Year = meta.Date[:4]
+		}
+		if meta.Title != "" || meta.Artist != "" || meta.Album != "" {
+			return meta
+		}
+	}
+	return nil
+}
+
+// GetWAVQuality probes PCM parameters and computes duration from the data size.
+func GetWAVQuality(filePath string) (*WAVQuality, error) {
+	f, err := os.Open(filePath)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	p, err := streamProbeWAV(f)
+	if err != nil {
+		return nil, err
+	}
+	q := &WAVQuality{
+		SampleRate: p.sampleRate,
+		BitDepth:   p.bitDepth,
+		Channels:   p.channels,
+	}
+	if p.byteRate > 0 && p.dataSize > 0 {
+		q.Duration = int(p.dataSize / int64(p.byteRate))
+	} else if p.sampleRate > 0 && p.channels > 0 && p.bitDepth > 0 && p.dataSize > 0 {
+		bytesPerSec := int64(p.sampleRate * p.channels * p.bitDepth / 8)
+		if bytesPerSec > 0 {
+			q.Duration = int(p.dataSize / bytesPerSec)
+		}
+	}
+	return q, nil
+}
+
+// ReadWAVTags reads tags from a WAV file (ID3 chunk preferred, RIFF INFO fallback).
+func ReadWAVTags(filePath string) (*AudioMetadata, error) {
+	f, err := os.Open(filePath)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	p, err := streamProbeWAV(f)
+	if err != nil {
+		return nil, err
+	}
+	meta := wavMetadataFromProbe(p)
+	if meta == nil {
+		return nil, fmt.Errorf("no WAV tags found")
+	}
+	return meta, nil
+}
+
+type aiffProbe struct {
+	sampleRate     int
+	bitDepth       int
+	channels       int
+	numFrames      int64
+	id3            []byte
+	nameChunk      string
+	authChunk      string
+	annoChunk      string
+	copyrightChunk string
+}
+
+func streamProbeAIFF(f *os.File) (*aiffProbe, error) {
+	header := make([]byte, 12)
+	if _, err := io.ReadFull(f, header); err != nil {
+		return nil, err
+	}
+	form := string(header[8:12])
+	if string(header[0:4]) != "FORM" || (form != "AIFF" && form != "AIFC") {
+		return nil, fmt.Errorf("not an AIFF file")
+	}
+
+	p := &aiffProbe{}
+	hdr := make([]byte, 8)
+	for {
+		if _, err := io.ReadFull(f, hdr); err != nil {
+			break
+		}
+		id := string(hdr[0:4])
+		size := readUint32(hdr[4:8], false)
+		pad := int64(size) & 1
+
+		switch id {
+		case "COMM":
+			buf := make([]byte, size)
+			if _, err := io.ReadFull(f, buf); err != nil {
+				return p, nil
+			}
+			if len(buf) >= 18 {
+				p.channels = int(binary.BigEndian.Uint16(buf[0:2]))
+				p.numFrames = int64(binary.BigEndian.Uint32(buf[2:6]))
+				p.bitDepth = int(binary.BigEndian.Uint16(buf[6:8]))
+				p.sampleRate = int(parseExtendedFloat80(buf[8:18]) + 0.5)
+			}
+			if pad == 1 {
+				f.Seek(pad, io.SeekCurrent)
+			}
+		case id3ChunkAIFF, "id3 ":
+			if size > 0 && size <= wavMaxMetaChunk {
+				buf := make([]byte, size)
+				if _, err := io.ReadFull(f, buf); err == nil {
+					p.id3 = buf
+				}
+				if pad == 1 {
+					f.Seek(pad, io.SeekCurrent)
+				}
+			} else {
+				f.Seek(int64(size)+pad, io.SeekCurrent)
+			}
+		case "NAME", "AUTH", "ANNO", "(c) ":
+			if size > 0 && size <= wavMaxMetaChunk {
+				buf := make([]byte, size)
+				if _, err := io.ReadFull(f, buf); err == nil {
+					val := strings.TrimRight(strings.TrimSpace(string(buf)), "\x00")
+					switch id {
+					case "NAME":
+						p.nameChunk = val
+					case "AUTH":
+						p.authChunk = val
+					case "ANNO":
+						p.annoChunk = val
+					case "(c) ":
+						p.copyrightChunk = val
+					}
+				}
+				if pad == 1 {
+					f.Seek(pad, io.SeekCurrent)
+				}
+			} else {
+				f.Seek(int64(size)+pad, io.SeekCurrent)
+			}
+		default:
+			f.Seek(int64(size)+pad, io.SeekCurrent)
+		}
+	}
+	return p, nil
+}
+
+func aiffMetadataFromProbe(p *aiffProbe) *AudioMetadata {
+	if p == nil {
+		return nil
+	}
+	if len(p.id3) > 0 {
+		if meta, err := readID3v2FromBytes(p.id3); err == nil && meta != nil &&
+			(meta.Title != "" || meta.Artist != "" || meta.Album != "") {
+			return meta
+		}
+	}
+	if p.nameChunk != "" || p.authChunk != "" {
+		meta := &AudioMetadata{
+			Title:     p.nameChunk,
+			Artist:    p.authChunk,
+			Comment:   p.annoChunk,
+			Copyright: p.copyrightChunk,
+		}
+		return meta
+	}
+	return nil
+}
+
+// GetAIFFQuality probes PCM parameters and computes duration from frame count.
+func GetAIFFQuality(filePath string) (*WAVQuality, error) {
+	f, err := os.Open(filePath)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	p, err := streamProbeAIFF(f)
+	if err != nil {
+		return nil, err
+	}
+	q := &WAVQuality{
+		SampleRate: p.sampleRate,
+		BitDepth:   p.bitDepth,
+		Channels:   p.channels,
+	}
+	if p.sampleRate > 0 && p.numFrames > 0 {
+		q.Duration = int(p.numFrames / int64(p.sampleRate))
+	}
+	return q, nil
+}
+
+// ReadAIFFTags reads tags from an AIFF file (ID3 chunk preferred, AIFF text chunks fallback).
+func ReadAIFFTags(filePath string) (*AudioMetadata, error) {
+	f, err := os.Open(filePath)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	p, err := streamProbeAIFF(f)
+	if err != nil {
+		return nil, err
+	}
+	meta := aiffMetadataFromProbe(p)
+	if meta == nil {
+		return nil, fmt.Errorf("no AIFF tags found")
+	}
+	return meta, nil
+}
+
+// readID3v2FromBytes parses an in-memory ID3v2 tag (the contents of a WAV "id3 "
+// or AIFF "ID3 " chunk) by reusing the existing frame parsers.
+func readID3v2FromBytes(data []byte) (*AudioMetadata, error) {
+	if len(data) < 10 || string(data[0:3]) != "ID3" {
+		return nil, fmt.Errorf("no ID3v2 header")
+	}
+	majorVersion := data[3]
+	flags := data[5]
+	unsync := (flags & 0x80) != 0
+	extendedHeader := (flags & 0x40) != 0
+	footerPresent := (flags & 0x10) != 0
+
+	size := synchsafeDecode(data[6:10])
+	if size <= 0 || 10+size > len(data) {
+		size = len(data) - 10
+	}
+	tagData := data[10 : 10+size]
+
+	if footerPresent && len(tagData) >= 10 {
+		footerStart := len(tagData) - 10
+		if footerStart >= 0 && string(tagData[footerStart:footerStart+3]) == "3DI" {
+			tagData = tagData[:footerStart]
+		}
+	}
+	if extendedHeader {
+		if skip := extendedHeaderSize(tagData, majorVersion); skip > 0 && skip < len(tagData) {
+			tagData = tagData[skip:]
+		}
+	}
+
+	metadata := &AudioMetadata{}
+	if majorVersion == 2 {
+		parseID3v22Frames(tagData, metadata, unsync)
+	} else {
+		parseID3v23Frames(tagData, metadata, majorVersion, unsync)
+	}
+	return metadata, nil
+}
+
+// extractAPICFromID3 returns the first embedded picture (APIC/PIC) and its MIME.
+func extractAPICFromID3(tag []byte) ([]byte, string) {
+	if len(tag) < 10 || string(tag[0:3]) != "ID3" {
+		return nil, ""
+	}
+	ver := tag[3]
+	size := synchsafeDecode(tag[6:10])
+	if size <= 0 || 10+size > len(tag) {
+		size = len(tag) - 10
+	}
+	data := tag[10 : 10+size]
+
+	pos := 0
+	for {
+		if ver == 2 {
+			if pos+6 > len(data) || data[pos] == 0 {
+				break
+			}
+			id := string(data[pos : pos+3])
+			fsz := int(data[pos+3])<<16 | int(data[pos+4])<<8 | int(data[pos+5])
+			if fsz <= 0 || pos+6+fsz > len(data) {
+				break
+			}
+			if id == "PIC" {
+				return parseAPICFrame(data[pos+6:pos+6+fsz], ver)
+			}
+			pos += 6 + fsz
+			continue
+		}
+
+		if pos+10 > len(data) || data[pos] == 0 {
+			break
+		}
+		id := string(data[pos : pos+4])
+		var fsz int
+		if ver == 4 {
+			fsz = synchsafeDecode(data[pos+4 : pos+8])
+		} else {
+			fsz = int(binary.BigEndian.Uint32(data[pos+4 : pos+8]))
+		}
+		if fsz <= 0 || pos+10+fsz > len(data) {
+			break
+		}
+		if id == "APIC" {
+			return parseAPICFrame(data[pos+10:pos+10+fsz], ver)
+		}
+		pos += 10 + fsz
+	}
+	return nil, ""
+}
+
+// buildID3v24Tag builds a UTF-8 ID3v2.4 tag from metadata plus optional cover.
+func buildID3v24Tag(meta *AudioMetadata, coverData []byte, coverMIME string) []byte {
+	var frames bytes.Buffer
+
+	writeFrame := func(id string, payload []byte) {
+		frames.WriteString(id)
+		frames.Write(synchsafeEncode(len(payload)))
+		frames.Write([]byte{0, 0})
+		frames.Write(payload)
+	}
+	writeText := func(id, val string) {
+		if strings.TrimSpace(val) == "" {
+			return
+		}
+		payload := append([]byte{0x03}, []byte(val)...)
+		writeFrame(id, payload)
+	}
+
+	writeText("TIT2", meta.Title)
+	writeText("TPE1", meta.Artist)
+	writeText("TALB", meta.Album)
+	writeText("TPE2", meta.AlbumArtist)
+	writeText("TCON", meta.Genre)
+	writeText("TCOM", meta.Composer)
+	writeText("TPUB", meta.Label)
+	writeText("TCOP", meta.Copyright)
+	writeText("TSRC", meta.ISRC)
+
+	date := meta.Date
+	if date == "" {
+		date = meta.Year
+	}
+	writeText("TDRC", date)
+
+	if meta.TrackNumber > 0 {
+		if meta.TotalTracks > 0 {
+			writeText("TRCK", fmt.Sprintf("%d/%d", meta.TrackNumber, meta.TotalTracks))
+		} else {
+			writeText("TRCK", strconv.Itoa(meta.TrackNumber))
+		}
+	}
+	if meta.DiscNumber > 0 {
+		if meta.TotalDiscs > 0 {
+			writeText("TPOS", fmt.Sprintf("%d/%d", meta.DiscNumber, meta.TotalDiscs))
+		} else {
+			writeText("TPOS", strconv.Itoa(meta.DiscNumber))
+		}
+	}
+
+	if strings.TrimSpace(meta.Comment) != "" {
+		// COMM: encoding + language(3) + short desc(null) + text
+		payload := []byte{0x03}
+		payload = append(payload, []byte("eng")...)
+		payload = append(payload, 0x00) // empty description
+		payload = append(payload, []byte(meta.Comment)...)
+		writeFrame("COMM", payload)
+	}
+	if strings.TrimSpace(meta.Lyrics) != "" {
+		payload := []byte{0x03}
+		payload = append(payload, []byte("eng")...)
+		payload = append(payload, 0x00)
+		payload = append(payload, []byte(meta.Lyrics)...)
+		writeFrame("USLT", payload)
+	}
+
+	// ReplayGain as TXXX (description\0value), UTF-8.
+	writeTXXX := func(desc, val string) {
+		if strings.TrimSpace(val) == "" {
+			return
+		}
+		payload := []byte{0x03}
+		payload = append(payload, []byte(desc)...)
+		payload = append(payload, 0x00)
+		payload = append(payload, []byte(val)...)
+		writeFrame("TXXX", payload)
+	}
+	writeTXXX("REPLAYGAIN_TRACK_GAIN", meta.ReplayGainTrackGain)
+	writeTXXX("REPLAYGAIN_TRACK_PEAK", meta.ReplayGainTrackPeak)
+	writeTXXX("REPLAYGAIN_ALBUM_GAIN", meta.ReplayGainAlbumGain)
+	writeTXXX("REPLAYGAIN_ALBUM_PEAK", meta.ReplayGainAlbumPeak)
+
+	if len(coverData) > 0 {
+		if strings.TrimSpace(coverMIME) == "" {
+			coverMIME = "image/jpeg"
+		}
+		// APIC: encoding + mime(null) + picture-type(0x03 front) + desc(null) + data
+		payload := []byte{0x03}
+		payload = append(payload, []byte(coverMIME)...)
+		payload = append(payload, 0x00)
+		payload = append(payload, 0x03)
+		payload = append(payload, 0x00)
+		payload = append(payload, coverData...)
+		writeFrame("APIC", payload)
+	}
+
+	body := frames.Bytes()
+	var out bytes.Buffer
+	out.WriteString("ID3")
+	out.Write([]byte{0x04, 0x00}) // v2.4.0
+	out.WriteByte(0x00)           // flags
+	out.Write(synchsafeEncode(len(body)))
+	out.Write(body)
+	return out.Bytes()
+}
+
+// writeID3Chunk rewrites filePath, replacing any existing tag chunk (chunkID,
+// matched case-insensitively) with a fresh ID3v2.4 chunk appended at the end.
+// The audio data and all other chunks are preserved; container size is patched.
+func writeID3Chunk(filePath, expectMagic, chunkID string, le bool, id3 []byte) error {
+	in, err := os.Open(filePath)
+	if err != nil {
+		return err
+	}
+	defer in.Close()
+
+	header := make([]byte, 12)
+	if _, err := io.ReadFull(in, header); err != nil {
+		return err
+	}
+	if string(header[0:4]) != expectMagic {
+		return fmt.Errorf("unexpected container magic %q", string(header[0:4]))
+	}
+
+	tmpPath := filePath + ".tagtmp"
+	out, err := os.Create(tmpPath)
+	if err != nil {
+		return err
+	}
+	cleanup := func() {
+		out.Close()
+		os.Remove(tmpPath)
+	}
+
+	if _, err := out.Write(header); err != nil {
+		cleanup()
+		return err
+	}
+
+	var bodyLen int64 = 4 // the 4-byte form type after the size field
+	hdr := make([]byte, 8)
+	for {
+		n, rerr := io.ReadFull(in, hdr)
+		if n < 8 {
+			break
+		}
+		if rerr != nil {
+			break
+		}
+		id := string(hdr[0:4])
+		size := readUint32(hdr[4:8], le)
+		pad := int64(size) & 1
+
+		if strings.EqualFold(id, chunkID) {
+			if _, err := in.Seek(int64(size)+pad, io.SeekCurrent); err != nil {
+				cleanup()
+				return err
+			}
+			continue
+		}
+
+		if _, err := out.Write(hdr); err != nil {
+			cleanup()
+			return err
+		}
+		if _, err := io.CopyN(out, in, int64(size)+pad); err != nil {
+			cleanup()
+			return err
+		}
+		bodyLen += 8 + int64(size) + pad
+	}
+
+	newSize := len(id3)
+	chunkHdr := make([]byte, 8)
+	copy(chunkHdr[0:4], chunkID)
+	putUint32(chunkHdr[4:8], le, uint32(newSize))
+	if _, err := out.Write(chunkHdr); err != nil {
+		cleanup()
+		return err
+	}
+	if _, err := out.Write(id3); err != nil {
+		cleanup()
+		return err
+	}
+	if newSize&1 == 1 {
+		if _, err := out.Write([]byte{0}); err != nil {
+			cleanup()
+			return err
+		}
+	}
+	bodyLen += 8 + int64(newSize) + int64(newSize&1)
+
+	// Patch the container size field (bytes 4..8).
+	sizeBuf := make([]byte, 4)
+	putUint32(sizeBuf, le, uint32(bodyLen))
+	if _, err := out.WriteAt(sizeBuf, 4); err != nil {
+		cleanup()
+		return err
+	}
+
+	if err := out.Close(); err != nil {
+		os.Remove(tmpPath)
+		return err
+	}
+	in.Close()
+
+	return os.Rename(tmpPath, filePath)
+}
+
+func loadCoverForTag(fields map[string]string) ([]byte, string) {
+	coverPath := strings.TrimSpace(fields["cover_path"])
+	if coverPath == "" {
+		return nil, ""
+	}
+	data, err := os.ReadFile(coverPath)
+	if err != nil || len(data) == 0 {
+		return nil, ""
+	}
+	mime := "image/jpeg"
+	if len(data) >= 8 && data[0] == 0x89 && data[1] == 0x50 && data[2] == 0x4E && data[3] == 0x47 {
+		mime = "image/png"
+	}
+	return data, mime
+}
+
+func audioMetadataFromEditFields(fields map[string]string) *AudioMetadata {
+	atoi := func(k string) int {
+		n := 0
+		if v, ok := fields[k]; ok && strings.TrimSpace(v) != "" {
+			fmt.Sscanf(strings.TrimSpace(v), "%d", &n)
+		}
+		return n
+	}
+	return &AudioMetadata{
+		Title:               fields["title"],
+		Artist:              fields["artist"],
+		Album:               fields["album"],
+		AlbumArtist:         fields["album_artist"],
+		Date:                fields["date"],
+		TrackNumber:         atoi("track_number"),
+		TotalTracks:         atoi("track_total"),
+		DiscNumber:          atoi("disc_number"),
+		TotalDiscs:          atoi("disc_total"),
+		ISRC:                fields["isrc"],
+		Lyrics:              fields["lyrics"],
+		Genre:               fields["genre"],
+		Label:               fields["label"],
+		Copyright:           fields["copyright"],
+		Composer:            fields["composer"],
+		Comment:             fields["comment"],
+		ReplayGainTrackGain: fields["replaygain_track_gain"],
+		ReplayGainTrackPeak: fields["replaygain_track_peak"],
+		ReplayGainAlbumGain: fields["replaygain_album_gain"],
+		ReplayGainAlbumPeak: fields["replaygain_album_peak"],
+	}
+}
+
+// mergeWAVEditFields merges edit fields onto existing tags so untouched fields
+// (and cover art, when no new cover is provided) are preserved.
+func mergeEditFieldsOntoExisting(existing *AudioMetadata, fields map[string]string) *AudioMetadata {
+	meta := audioMetadataFromEditFields(fields)
+	if existing == nil {
+		return meta
+	}
+	// Only overwrite fields that are present as keys in the edit set; otherwise
+	// keep the existing value. An empty value with the key present clears it.
+	keep := func(key, newVal, oldVal string) string {
+		if _, ok := fields[key]; ok {
+			return newVal
+		}
+		return oldVal
+	}
+	meta.Title = keep("title", meta.Title, existing.Title)
+	meta.Artist = keep("artist", meta.Artist, existing.Artist)
+	meta.Album = keep("album", meta.Album, existing.Album)
+	meta.AlbumArtist = keep("album_artist", meta.AlbumArtist, existing.AlbumArtist)
+	meta.Genre = keep("genre", meta.Genre, existing.Genre)
+	meta.Composer = keep("composer", meta.Composer, existing.Composer)
+	meta.Label = keep("label", meta.Label, existing.Label)
+	meta.Copyright = keep("copyright", meta.Copyright, existing.Copyright)
+	meta.ISRC = keep("isrc", meta.ISRC, existing.ISRC)
+	meta.Lyrics = keep("lyrics", meta.Lyrics, existing.Lyrics)
+	meta.Comment = keep("comment", meta.Comment, existing.Comment)
+	meta.Date = keep("date", meta.Date, existing.Date)
+	if _, ok := fields["track_number"]; !ok {
+		meta.TrackNumber = existing.TrackNumber
+	}
+	if _, ok := fields["track_total"]; !ok {
+		meta.TotalTracks = existing.TotalTracks
+	}
+	if _, ok := fields["disc_number"]; !ok {
+		meta.DiscNumber = existing.DiscNumber
+	}
+	if _, ok := fields["disc_total"]; !ok {
+		meta.TotalDiscs = existing.TotalDiscs
+	}
+	if _, ok := fields["replaygain_track_gain"]; !ok {
+		meta.ReplayGainTrackGain = existing.ReplayGainTrackGain
+	}
+	if _, ok := fields["replaygain_track_peak"]; !ok {
+		meta.ReplayGainTrackPeak = existing.ReplayGainTrackPeak
+	}
+	if _, ok := fields["replaygain_album_gain"]; !ok {
+		meta.ReplayGainAlbumGain = existing.ReplayGainAlbumGain
+	}
+	if _, ok := fields["replaygain_album_peak"]; !ok {
+		meta.ReplayGainAlbumPeak = existing.ReplayGainAlbumPeak
+	}
+	return meta
+}
+
+// WriteWAVTags writes/merges tags into a WAV file's "id3 " chunk.
+func WriteWAVTags(filePath string, fields map[string]string) error {
+	existing, _ := ReadWAVTags(filePath)
+	meta := mergeEditFieldsOntoExisting(existing, fields)
+
+	coverData, coverMIME := loadCoverForTag(fields)
+	if coverData == nil {
+		// Preserve an existing embedded cover when no new one is supplied.
+		if f, err := os.Open(filePath); err == nil {
+			if p, perr := streamProbeWAV(f); perr == nil && len(p.id3) > 0 {
+				coverData, coverMIME = extractAPICFromID3(p.id3)
+			}
+			f.Close()
+		}
+	}
+
+	tag := buildID3v24Tag(meta, coverData, coverMIME)
+	return writeID3Chunk(filePath, "RIFF", id3ChunkWAV, true, tag)
+}
+
+// WriteAIFFTags writes/merges tags into an AIFF file's "ID3 " chunk.
+func WriteAIFFTags(filePath string, fields map[string]string) error {
+	existing, _ := ReadAIFFTags(filePath)
+	meta := mergeEditFieldsOntoExisting(existing, fields)
+
+	coverData, coverMIME := loadCoverForTag(fields)
+	if coverData == nil {
+		if f, err := os.Open(filePath); err == nil {
+			if p, perr := streamProbeAIFF(f); perr == nil && len(p.id3) > 0 {
+				coverData, coverMIME = extractAPICFromID3(p.id3)
+			}
+			f.Close()
+		}
+	}
+
+	tag := buildID3v24Tag(meta, coverData, coverMIME)
+	return writeID3Chunk(filePath, "FORM", id3ChunkAIFF, false, tag)
+}
+
+func scanWAVFile(filePath string, result *LibraryScanResult, displayNameHint string) (*LibraryScanResult, error) {
+	if metadata, err := ReadWAVTags(filePath); err == nil && metadata != nil {
+		applyAudioMetadataToScan(metadata, result)
+	}
+	if quality, err := GetWAVQuality(filePath); err == nil && quality != nil {
+		result.BitDepth = quality.BitDepth
+		result.SampleRate = quality.SampleRate
+		result.Duration = quality.Duration
+	}
+	result.Bitrate = 0 // lossless PCM
+	result.Format = "wav"
+	applyDefaultLibraryMetadata(filePath, displayNameHint, result)
+	return result, nil
+}
+
+func scanAIFFFile(filePath string, result *LibraryScanResult, displayNameHint string) (*LibraryScanResult, error) {
+	if metadata, err := ReadAIFFTags(filePath); err == nil && metadata != nil {
+		applyAudioMetadataToScan(metadata, result)
+	}
+	if quality, err := GetAIFFQuality(filePath); err == nil && quality != nil {
+		result.BitDepth = quality.BitDepth
+		result.SampleRate = quality.SampleRate
+		result.Duration = quality.Duration
+	}
+	result.Bitrate = 0 // lossless PCM
+	result.Format = "aiff"
+	applyDefaultLibraryMetadata(filePath, displayNameHint, result)
+	return result, nil
+}
+
+func applyAudioMetadataToScan(metadata *AudioMetadata, result *LibraryScanResult) {
+	result.TrackName = metadata.Title
+	result.ArtistName = metadata.Artist
+	result.AlbumName = metadata.Album
+	result.AlbumArtist = metadata.AlbumArtist
+	result.ISRC = metadata.ISRC
+	result.TrackNumber = metadata.TrackNumber
+	result.TotalTracks = metadata.TotalTracks
+	result.DiscNumber = metadata.DiscNumber
+	result.TotalDiscs = metadata.TotalDiscs
+	if metadata.Date != "" {
+		result.ReleaseDate = metadata.Date
+	} else {
+		result.ReleaseDate = metadata.Year
+	}
+	result.Genre = metadata.Genre
+	result.Composer = metadata.Composer
+	result.Label = metadata.Label
+	result.Copyright = metadata.Copyright
+}
+
+// extractWAVAIFFCover returns embedded cover art (from the ID3 chunk) for a
+// WAV or AIFF file, or an error when none is present.
+func extractWAVAIFFCover(filePath string) ([]byte, string, error) {
+	ext := strings.ToLower(filepath.Ext(filePath))
+	f, err := os.Open(filePath)
+	if err != nil {
+		return nil, "", err
+	}
+	defer f.Close()
+
+	var id3 []byte
+	switch ext {
+	case ".aiff", ".aif", ".aifc":
+		if p, perr := streamProbeAIFF(f); perr == nil {
+			id3 = p.id3
+		}
+	default:
+		if p, perr := streamProbeWAV(f); perr == nil {
+			id3 = p.id3
+		}
+	}
+	if len(id3) == 0 {
+		return nil, "", fmt.Errorf("no embedded cover")
+	}
+	data, mime := extractAPICFromID3(id3)
+	if len(data) == 0 {
+		return nil, "", fmt.Errorf("no embedded cover")
+	}
+	return data, mime, nil
+}

ios/Runner/AppDelegate.swift

@@ -1,6 +1,6 @@
 import Flutter
 import UIKit
-import Gobackend  // Import Go framework
+import Gobackend
 
 @main
 @objc class AppDelegate: FlutterAppDelegate {
@@ -17,9 +17,16 @@ import Gobackend  // Import Go framework
     private var libraryScanProgressTimer: DispatchSourceTimer?
     private var libraryScanProgressEventSink: FlutterEventSink?
     private var lastLibraryScanProgressPayload: String?
+    private var backendChannel: FlutterMethodChannel?
+    private var pendingSessionGrantEvents: [[String: Any]] = []
     
     /// Currently accessed security-scoped URL for library folder
     private var activeSecurityScopedURL: URL?
+
+    /// Whether a download queue is active; while true a background task is
+    /// started on each background entry to extend execution time. Main-thread only.
+    private var downloadsActive = false
+    private var downloadBackgroundTask: UIBackgroundTaskIdentifier = .invalid
     
     override func application(
         _ application: UIApplication,
@@ -34,6 +41,14 @@ import Gobackend  // Import Go framework
             name: CHANNEL,
             binaryMessenger: controller.binaryMessenger
         )
+        backendChannel = channel
+        if !pendingSessionGrantEvents.isEmpty {
+            let events = pendingSessionGrantEvents
+            pendingSessionGrantEvents.removeAll()
+            for event in events {
+                channel.invokeMethod("extensionSessionGrantCompleted", arguments: event)
+            }
+        }
         let downloadProgressEvents = FlutterEventChannel(
             name: DOWNLOAD_PROGRESS_STREAM_CHANNEL,
             binaryMessenger: controller.binaryMessenger
@@ -78,20 +93,25 @@ import Gobackend  // Import Go framework
         return super.application(application, didFinishLaunchingWithOptions: launchOptions)
     }
 
-    /// PKCE OAuth return URL: spotiflac://callback?code=...&state=<extension_id>
+    /// Extension return URLs:
+    /// - OAuth: spotiflac://callback?code=...&state=<extension_id>
+    /// - Signed session: spotiflac://session-grant?grant=...&state=<extension_id>
     @discardableResult
     private func handleExtensionOAuthRedirect(url: URL) -> Bool {
         guard let scheme = url.scheme?.lowercased(), scheme == "spotiflac" else { return false }
         let host = (url.host ?? "").lowercased()
         let path = url.path.lowercased()
+        let isSessionGrant = host == "session-grant"
         let ok =
-            host == "callback" || host == "spotify-callback" || path.contains("callback")
+            isSessionGrant || host == "callback" || host == "spotify-callback" || path.contains("callback")
         guard ok else { return false }
         guard let components = URLComponents(url: url, resolvingAgainstBaseURL: false) else {
             return false
         }
         let q = components.queryItems ?? []
         let code =
+            q.first { $0.name == (isSessionGrant ? "grant" : "code") }?.value?.trimmingCharacters(
+                in: .whitespacesAndNewlines) ??
             q.first { $0.name == "code" }?.value?.trimmingCharacters(
                 in: .whitespacesAndNewlines) ?? ""
         let state =
@@ -104,16 +124,37 @@ import Gobackend  // Import Go framework
         }
         streamQueue.async {
             var err: NSError?
-            GobackendSetExtensionAuthCodeByID(state, code)
-            _ = GobackendInvokeExtensionActionJSON(state, "completeSpotifyLogin", &err)
+            if isSessionGrant {
+                GobackendSetExtensionSessionGrantByID(state, code)
+                _ = GobackendInvokeExtensionActionJSON(state, "completeGrant", &err)
+            } else {
+                GobackendSetExtensionAuthCodeByID(state, code)
+                _ = GobackendInvokeExtensionActionJSON(state, "completeSpotifyLogin", &err)
+            }
             if let err = err {
                 NSLog(
-                    "SpotiFLAC: Extension OAuth complete failed: \(err.localizedDescription)")
+                    "SpotiFLAC: Extension callback complete failed: \(err.localizedDescription)")
+            } else if isSessionGrant {
+                DispatchQueue.main.async { [weak self] in
+                    self?.notifySessionGrantCompleted(extensionId: state)
+                }
             }
         }
         return true
     }
 
+    private func notifySessionGrantCompleted(extensionId: String) {
+        let payload: [String: Any] = [
+            "extension_id": extensionId,
+            "success": true,
+        ]
+        if let channel = backendChannel {
+            channel.invokeMethod("extensionSessionGrantCompleted", arguments: payload)
+        } else {
+            pendingSessionGrantEvents.append(payload)
+        }
+    }
+
     override func application(
         _ app: UIApplication,
         open url: URL,
@@ -233,6 +274,20 @@ import Gobackend  // Import Go framework
     }
     
     private func handleMethodCall(call: FlutterMethodCall, result: @escaping FlutterResult) {
+        switch call.method {
+        case "beginBackgroundDownloadTask":
+            downloadsActive = true
+            result(nil)
+            return
+        case "endBackgroundDownloadTask":
+            downloadsActive = false
+            endBackgroundDownloadTask()
+            result(nil)
+            return
+        default:
+            break
+        }
+
         DispatchQueue.global(qos: .userInitiated).async {
             do {
                 let response = try self.invokeGoMethod(call: call)
@@ -246,6 +301,34 @@ import Gobackend  // Import Go framework
             }
         }
     }
+
+    override func applicationDidEnterBackground(_ application: UIApplication) {
+        super.applicationDidEnterBackground(application)
+        if downloadsActive {
+            beginBackgroundDownloadTask()
+        }
+    }
+
+    override func applicationWillEnterForeground(_ application: UIApplication) {
+        super.applicationWillEnterForeground(application)
+        endBackgroundDownloadTask()
+    }
+
+    private func beginBackgroundDownloadTask() {
+        if downloadBackgroundTask != .invalid { return }
+        downloadBackgroundTask = UIApplication.shared.beginBackgroundTask(
+            withName: "SpotiFLACDownloads"
+        ) { [weak self] in
+            self?.endBackgroundDownloadTask()
+        }
+    }
+
+    private func endBackgroundDownloadTask() {
+        if downloadBackgroundTask != .invalid {
+            UIApplication.shared.endBackgroundTask(downloadBackgroundTask)
+            downloadBackgroundTask = .invalid
+        }
+    }
     
     private func invokeGoMethod(call: FlutterMethodCall) throws -> Any? {
         var error: NSError?
@@ -310,6 +393,12 @@ import Gobackend  // Import Go framework
             let insecureTLS = args["insecure_tls"] as? Bool ?? false
             GobackendSetNetworkCompatibilityOptions(allowHTTP, insecureTLS)
             return nil
+
+        case "setAllowPrivateNetwork":
+            let args = call.arguments as! [String: Any]
+            let allowed = args["allowed"] as? Bool ?? false
+            GobackendSetAllowPrivateNetwork(allowed)
+            return nil
             
         case "checkDuplicate":
             let args = call.arguments as! [String: Any]
@@ -543,7 +632,6 @@ import Gobackend  // Import Go framework
             GobackendClearTrackCache()
             return nil
             
-        // Log methods
         case "getLogs":
             let response = GobackendGetLogs()
             return response
@@ -568,7 +656,6 @@ import Gobackend  // Import Go framework
             GobackendSetLoggingEnabled(enabled)
             return nil
             
-        // Extension System methods
         case "initExtensionSystem":
             let args = call.arguments as! [String: Any]
             let extensionsDir = args["extensions_dir"] as! String
@@ -733,7 +820,6 @@ import Gobackend  // Import Go framework
             GobackendCleanupExtensions()
             return nil
             
-        // Extension Auth API
         case "getExtensionPendingAuth":
             let args = call.arguments as! [String: Any]
             let extensionId = args["extension_id"] as! String
@@ -774,7 +860,6 @@ import Gobackend  // Import Go framework
             if let error = error { throw error }
             return response
             
-        // Extension FFmpeg API
         case "getPendingFFmpegCommand":
             let args = call.arguments as! [String: Any]
             let commandId = args["command_id"] as! String
@@ -796,7 +881,6 @@ import Gobackend  // Import Go framework
             if let error = error { throw error }
             return response
             
-        // Extension Custom Search API
         case "customSearchWithExtension":
             let args = call.arguments as! [String: Any]
             let extensionId = args["extension_id"] as! String
@@ -818,7 +902,6 @@ import Gobackend  // Import Go framework
             if let error = error { throw error }
             return response
             
-        // Extension URL Handler API
         case "handleURLWithExtension":
             let args = call.arguments as! [String: Any]
             let url = args["url"] as! String
@@ -837,7 +920,6 @@ import Gobackend  // Import Go framework
             if let error = error { throw error }
             return response
             
-        // Extension Post-Processing API
         case "runPostProcessing":
             let args = call.arguments as! [String: Any]
             let filePath = args["file_path"] as! String
@@ -859,7 +941,6 @@ import Gobackend  // Import Go framework
             if let error = error { throw error }
             return response
             
-        // Extension Store
         case "initExtensionStore":
             let args = call.arguments as! [String: Any]
             let cacheDir = args["cache_dir"] as! String
@@ -917,7 +998,6 @@ import Gobackend  // Import Go framework
             if let error = error { throw error }
             return nil
             
-        // Extension Home Feed API
         case "getExtensionHomeFeed":
             let args = call.arguments as! [String: Any]
             let extensionId = args["extension_id"] as! String
@@ -933,7 +1013,6 @@ import Gobackend  // Import Go framework
             if let error = error { throw error }
             return response
             
-        // Local Library Scanning
         case "setLibraryCoverCacheDir":
             let args = call.arguments as! [String: Any]
             let cacheDir = args["cache_dir"] as! String
@@ -970,7 +1049,6 @@ import Gobackend  // Import Go framework
             if let error = error { throw error }
             return response
         
-        // iOS Security-Scoped Bookmark for Local Library
         case "resolveIosBookmark":
             let args = call.arguments as! [String: Any]
             let bookmarkBase64 = args["bookmark"] as! String
@@ -990,7 +1068,6 @@ import Gobackend  // Import Go framework
             let path = args["path"] as! String
             return try createIosBookmarkFromPath(path)
             
-        // Lyrics Provider Settings
         case "setLyricsProviders":
             let args = call.arguments as! [String: Any]
             let providersJson = args["providers_json"] as? String ?? "[]"
@@ -1020,7 +1097,6 @@ import Gobackend  // Import Go framework
             if let error = error { throw error }
             return response
             
-        // CUE Sheet Parsing
         case "parseCueSheet":
             let args = call.arguments as! [String: Any]
             let cuePath = args["cue_path"] as! String

lib/app.dart

@@ -7,6 +7,7 @@ import 'package:spotiflac_android/screens/main_shell.dart';
 import 'package:spotiflac_android/screens/setup_screen.dart';
 import 'package:spotiflac_android/screens/tutorial_screen.dart';
 import 'package:spotiflac_android/providers/settings_provider.dart';
+import 'package:spotiflac_android/services/app_navigation_service.dart';
 import 'package:spotiflac_android/theme/dynamic_color_wrapper.dart';
 import 'package:spotiflac_android/l10n/app_localizations.dart';
 
@@ -28,6 +29,7 @@ final _routerProvider = Provider<GoRouter>((ref) {
   }
 
   return GoRouter(
+    navigatorKey: AppNavigationService.rootNavigatorKey,
     initialLocation: initialLocation,
     routes: [
       GoRoute(path: '/', builder: (context, state) => const MainShell()),
@@ -114,6 +116,15 @@ class SpotiFLACApp extends ConsumerWidget {
           scrollBehavior: scrollBehavior,
           themeAnimationDuration: const Duration(milliseconds: 300),
           themeAnimationCurve: Curves.easeInOut,
+          // Treat the display as one continuous surface so bottom sheets and
+          // dialogs stay centered on large/foldable devices.
+          builder: (context, child) {
+            final mediaQuery = MediaQuery.of(context);
+            return MediaQuery(
+              data: mediaQuery.copyWith(displayFeatures: const []),
+              child: child ?? const SizedBox.shrink(),
+            );
+          },
           routerConfig: router,
           locale: locale,
           localeResolutionCallback: (deviceLocale, supportedLocales) {

lib/constants/app_info.dart

@@ -1,8 +1,8 @@
 import 'package:flutter/foundation.dart';
 
 class AppInfo {
-  static const String version = '4.5.6';
-  static const String buildNumber = '133';
+  static const String version = '4.7.1';
+  static const String buildNumber = '137';
   static const String fullVersion = '$version+$buildNumber';
 
   static String get displayVersion => kDebugMode ? 'Internal' : version;

lib/l10n/app_localizations_en.dart

@@ -142,7 +142,7 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get optionsSwitchBack =>
-      'Tap Deezer or Spotify to switch back from extension';
+      'Choose the default search provider to switch back from an extension';
 
   @override
   String get optionsAutoFallback => 'Auto Fallback';
@@ -155,10 +155,12 @@ class AppLocalizationsEn extends AppLocalizations {
   String get optionsUseExtensionProviders => 'Use Extension Providers';
 
   @override
-  String get optionsUseExtensionProvidersOn => 'Extensions will be tried first';
+  String get optionsUseExtensionProvidersOn =>
+      'Extension providers are enabled';
 
   @override
-  String get optionsUseExtensionProvidersOff => 'Using built-in providers only';
+  String get optionsUseExtensionProvidersOff =>
+      'Extension providers are required';
 
   @override
   String get optionsEmbedLyrics => 'Embed Lyrics';
@@ -185,6 +187,43 @@ class AppLocalizationsEn extends AppLocalizations {
   String get optionsReplayGainSubtitleOff =>
       'Disabled: no loudness normalization tags';
 
+  @override
+  String get trackReplayGain => 'Rescan ReplayGain';
+
+  @override
+  String get trackReplayGainSubtitle =>
+      'Analyze loudness and write ReplayGain tags';
+
+  @override
+  String get trackReplayGainScanning => 'Analyzing loudness...';
+
+  @override
+  String get trackReplayGainSuccess => 'ReplayGain tags added';
+
+  @override
+  String get trackReplayGainFailed => 'Failed to add ReplayGain tags';
+
+  @override
+  String selectionReplayGainCount(int count) {
+    return 'ReplayGain ($count)';
+  }
+
+  @override
+  String get replayGainBatchConfirmTitle => 'Add ReplayGain';
+
+  @override
+  String replayGainBatchConfirmMessage(int count) {
+    return 'Analyze loudness and write ReplayGain tags to $count track(s)?';
+  }
+
+  @override
+  String get replayGainBatchAnalyzing => 'Analyzing ReplayGain...';
+
+  @override
+  String replayGainBatchSuccess(int success, int total) {
+    return 'ReplayGain added to $success of $total tracks';
+  }
+
   @override
   String get optionsArtistTagMode => 'Artist Tag Mode';
 
@@ -206,21 +245,6 @@ class AppLocalizationsEn extends AppLocalizations {
   String get optionsArtistTagModeSplitVorbisSubtitle =>
       'Write one artist tag per artist for FLAC and Opus; MP3 and M4A stay joined.';
 
-  @override
-  String get optionsConcurrentDownloads => 'Concurrent Downloads';
-
-  @override
-  String get optionsConcurrentSequential => 'Sequential (1 at a time)';
-
-  @override
-  String optionsConcurrentParallel(int count) {
-    return '$count parallel downloads';
-  }
-
-  @override
-  String get optionsConcurrentWarning =>
-      'Parallel downloads may trigger rate limiting';
-
   @override
   String get optionsExtensionStore => 'Extension Repo';
 
@@ -385,11 +409,11 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get aboutBinimumDesc =>
-      'The creator of QQDL & HiFi API. Without this API, Tidal downloads wouldn\'t exist!';
+      'The creator of QQDL & HiFi API. This project helped shape lossless download support.';
 
   @override
   String get aboutSachinsenalDesc =>
-      'The original HiFi project creator. The foundation of Tidal integration!';
+      'The original HiFi project creator. A foundation for lossless-source integration.';
 
   @override
   String get aboutSjdonadoDesc =>
@@ -579,6 +603,15 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get dialogDownload => 'Download';
 
+  @override
+  String get previewPlay => 'Play preview';
+
+  @override
+  String get previewStop => 'Stop preview';
+
+  @override
+  String get previewUnavailable => 'Preview unavailable';
+
   @override
   String get dialogDiscard => 'Discard';
 
@@ -953,7 +986,7 @@ class AppLocalizationsEn extends AppLocalizations {
       'Only enabled extensions with download-provider capability are listed here.';
 
   @override
-  String get providerBuiltIn => 'Built-in';
+  String get providerBuiltIn => 'Legacy';
 
   @override
   String get providerExtension => 'Extension';
@@ -1346,10 +1379,11 @@ class AppLocalizationsEn extends AppLocalizations {
   String get storeEmptyNoResults => 'No extensions found';
 
   @override
-  String get extensionDefaultProvider => 'Default (Deezer)';
+  String get extensionDefaultProvider => 'Default Search';
 
   @override
-  String get extensionDefaultProviderSubtitle => 'Use built-in search';
+  String get extensionDefaultProviderSubtitle =>
+      'Use the default metadata search';
 
   @override
   String get extensionAuthor => 'Author';
@@ -1523,7 +1557,7 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get downloadLossy320FormatDesc =>
-      'Choose the output format for Tidal 320kbps lossy downloads. The original AAC stream will be converted to your selected format.';
+      'Choose the output format for 320kbps lossy downloads. The original stream will be converted to your selected format when needed.';
 
   @override
   String get downloadLossyMp3 => 'MP3 320kbps';
@@ -1567,6 +1601,10 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get downloadAlbumFolderStructure => 'Album Folder Structure';
 
+  @override
+  String get albumFolderStructureDescription =>
+      'Choose how album folders are structured';
+
   @override
   String get downloadUseAlbumArtistForFolders => 'Use Album Artist for folders';
 
@@ -1910,7 +1948,7 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get libraryAboutDescription =>
-      'Scans your existing music collection to detect duplicates when downloading. Supports FLAC, M4A, MP3, Opus, and OGG formats. Metadata is read from file tags when available.';
+      'Scans your existing music collection to detect duplicates when downloading. Supports FLAC, ALAC, M4A, MP3, Opus, OGG, WAV, AIFF, and APE formats. Metadata is read from file tags when available.';
 
   @override
   String libraryTracksUnit(int count) {
@@ -2093,7 +2131,7 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get tutorialWelcomeTip2 =>
-      'Get FLAC quality audio from Tidal, Qobuz, or Deezer';
+      'Get FLAC quality audio from installed download extensions';
 
   @override
   String get tutorialWelcomeTip3 =>
@@ -2791,7 +2829,7 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get lyricsProvidersInfoText =>
-      'Extension lyrics providers always run before built-in providers. At least one provider must remain enabled.';
+      'Extension lyrics providers run before built-in lyrics providers. At least one provider must remain enabled.';
 
   @override
   String lyricsProvidersEnabledSection(int count) {
@@ -2833,6 +2871,10 @@ class AppLocalizationsEn extends AppLocalizations {
   String get lyricsProviderQqMusicDesc =>
       'QQ Music (good for Chinese songs, via proxy)';
 
+  @override
+  String get lyricsProviderLyricsPlusDesc =>
+      'Word-by-word karaoke lyrics (Apple/Musixmatch/Spotify/QQ, via proxy)';
+
   @override
   String get lyricsProviderExtensionDesc => 'Extension provider';
 
@@ -2856,6 +2898,164 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get settingsDonateSubtitle => 'Buy the developer a coffee';
 
+  @override
+  String get settingsBackup => 'Backup & Restore';
+
+  @override
+  String get settingsBackupSubtitle =>
+      'Move your library, history and settings to a new device';
+
+  @override
+  String get backupTitle => 'Backup & Restore';
+
+  @override
+  String get backupExportSectionTitle => 'Create backup';
+
+  @override
+  String get backupExportSectionDescription =>
+      'Save your settings, download history, liked tracks, wishlist, favorite artists and playlists into a single file you can keep or move to another phone.';
+
+  @override
+  String get backupExportButton => 'Create backup file';
+
+  @override
+  String get backupImportSectionTitle => 'Restore backup';
+
+  @override
+  String get backupImportSectionDescription =>
+      'Pick a backup file to restore your data. This replaces the current settings, history and library on this device.';
+
+  @override
+  String get backupImportButton => 'Choose backup file';
+
+  @override
+  String get backupCreating => 'Creating backup...';
+
+  @override
+  String get backupCreated => 'Backup created';
+
+  @override
+  String get backupCreateFailed => 'Failed to create backup';
+
+  @override
+  String get backupEmpty => 'There is nothing to back up yet';
+
+  @override
+  String get backupRestoreConfirmTitle => 'Restore this backup?';
+
+  @override
+  String get backupRestoreConfirmMessage =>
+      'This will replace your current settings, download history, liked tracks, wishlist and playlists with the contents of the backup. This cannot be undone.';
+
+  @override
+  String get backupRestoreConfirmButton => 'Restore';
+
+  @override
+  String get backupRestoring => 'Restoring backup...';
+
+  @override
+  String get backupRestored => 'Backup restored successfully';
+
+  @override
+  String get backupRestoreFailed => 'Failed to restore backup';
+
+  @override
+  String get backupInvalidFile => 'This file is not a valid SpotiFLAC backup';
+
+  @override
+  String get backupRestoreRestartHint =>
+      'Restart the app to make sure every change is applied.';
+
+  @override
+  String get backupContentsTitle => 'Backup contents';
+
+  @override
+  String get backupContentsSettings => 'App settings';
+
+  @override
+  String backupContentsHistory(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'items',
+      one: 'item',
+    );
+    return '$count history $_temp0';
+  }
+
+  @override
+  String backupContentsLiked(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return '$count liked $_temp0';
+  }
+
+  @override
+  String backupContentsWishlist(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return '$count wishlist $_temp0';
+  }
+
+  @override
+  String backupContentsPlaylists(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count playlists',
+      one: '1 playlist',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String backupContentsArtists(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count favorite artists',
+      one: '1 favorite artist',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String backupContentsExtensions(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count extensions',
+      one: '1 extension',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String get backupIncludeSecrets => 'Include extension credentials';
+
+  @override
+  String get backupIncludeSecretsDescription =>
+      'Tokens and API keys from extensions will be saved into the backup file. Keep the file private. When off, you re-enter them after restoring.';
+
+  @override
+  String backupExtensionsRestoreFailed(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'extensions',
+      one: 'extension',
+    );
+    return '$count $_temp0 could not be reinstalled. Install them manually from the store.';
+  }
+
   @override
   String get tooltipLoveAll => 'Love All';
 
@@ -2985,13 +3185,24 @@ class AppLocalizationsEn extends AppLocalizations {
   String get downloadNetworkCompatibilityModeDisabled =>
       'Using standard network settings';
 
+  @override
+  String get downloadAllowLocalNetwork => 'Allow Local Network Access';
+
+  @override
+  String get downloadAllowLocalNetworkEnabled =>
+      'Requests to local/private addresses are allowed (for local proxy or custom DNS)';
+
+  @override
+  String get downloadAllowLocalNetworkDisabled =>
+      'Local/private addresses are blocked for security';
+
   @override
   String get downloadSelectServiceToEnable =>
-      'Select Tidal or Qobuz to enable this option';
+      'Select a provider with quality options to enable this option';
 
   @override
   String get downloadSelectTidalQobuz =>
-      'Select Tidal or Qobuz to choose audio quality';
+      'Select a provider with quality options to choose audio quality';
 
   @override
   String get downloadEmbedLyricsDisabled => 'Enable metadata embedding first';
@@ -4245,4 +4456,318 @@ class AppLocalizationsEn extends AppLocalizations {
   String shareSheetLinkCopied(Object service) {
     return '$service link copied';
   }
+
+  @override
+  String get libraryPlayback => 'Playback';
+
+  @override
+  String get libraryExternalPlayer => 'External player';
+
+  @override
+  String get libraryExternalPlayerSubtitle =>
+      'Recommended for listening, best quality, gapless playback, EQ, and wider format support';
+
+  @override
+  String get libraryBuiltInPreviewPlayer => 'Built-in preview player';
+
+  @override
+  String get libraryBuiltInPreviewPlayerSubtitle =>
+      'Only for quick local previews inside SpotiFLAC Mobile, not recommended for regular listening';
+
+  @override
+  String get libraryBuiltInPlayerInfo =>
+      'The built-in player is a preview tool for checking local tracks quickly. Use an external music player for actual listening.';
+
+  @override
+  String get nowPlayingTitle => 'Now Playing';
+
+  @override
+  String get nowPlayingNothingPlaying => 'Nothing is playing';
+
+  @override
+  String get nowPlayingMinimize => 'Minimize';
+
+  @override
+  String get nowPlayingUpNext => 'Up next';
+
+  @override
+  String get nowPlayingDetails => 'Details';
+
+  @override
+  String get nowPlayingOpenInExternalPlayer => 'Open in external player';
+
+  @override
+  String get nowPlayingTabPlayer => 'Player';
+
+  @override
+  String get nowPlayingTabLyrics => 'Lyrics';
+
+  @override
+  String get nowPlayingNoLyrics => 'No lyrics in this file';
+
+  @override
+  String get nowPlayingLibraryEmpty => 'Your library is empty';
+
+  @override
+  String nowPlayingShuffleLibraryFailed(String error) {
+    return 'Could not shuffle library: $error';
+  }
+
+  @override
+  String get nowPlayingShuffleOn => 'Shuffle on';
+
+  @override
+  String get nowPlayingPlayInOrder => 'Play in order';
+
+  @override
+  String get nowPlayingShuffleLibrary => 'Shuffle library';
+
+  @override
+  String get nowPlayingQueueEmpty => 'Queue is empty';
+
+  @override
+  String get nowPlayingNoMetadata => 'No metadata available';
+
+  @override
+  String get announcementUnableToOpenLink =>
+      'Unable to open link. Please try again.';
+
+  @override
+  String trackConvertLosslessOutputWithCap(String quality) {
+    return 'Lossless output with $quality cap';
+  }
+
+  @override
+  String trackConvertConfirmMessageLosslessCapped(
+    String sourceFormat,
+    String targetFormat,
+    String quality,
+  ) {
+    return 'Convert from $sourceFormat to $targetFormat ($quality)?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original file will be deleted after conversion.';
+  }
+
+  @override
+  String selectionBatchConvertConfirmMessageLosslessCapped(
+    int count,
+    String format,
+    String quality,
+  ) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return 'Convert $count $_temp0 to $format ($quality)?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original files will be deleted after conversion.';
+  }
+
+  @override
+  String trackConvertActionLabelLossless(
+    String sourceFormat,
+    String targetFormat,
+    String quality,
+  ) {
+    return '$sourceFormat → $targetFormat ($quality)';
+  }
+
+  @override
+  String trackConvertActionLabelLossy(
+    String sourceFormat,
+    String targetFormat,
+    String bitrate,
+  ) {
+    return '$sourceFormat → $targetFormat @ $bitrate';
+  }
+
+  @override
+  String get aboutPaxsenixSubtitle =>
+      'Lyrics proxy for Musixmatch, Netease, Apple Music, QQ Music, Spotify, Deezer, YouTube, Kugou, and Genius';
+
+  @override
+  String get snackbarPlayingNext => 'Playing next';
+
+  @override
+  String get snackbarAddedToQueueGeneric => 'Added to queue';
+
+  @override
+  String selectionDeletePlaylistsCount(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'playlists',
+      one: 'playlist',
+    );
+    return 'Delete $count $_temp0';
+  }
+
+  @override
+  String get actionShuffle => 'Shuffle';
+
+  @override
+  String get downloadPrimaryArtistOnlyOn => 'Primary only: On';
+
+  @override
+  String get downloadPrimaryArtistOnlyOff => 'Primary only: Off';
+
+  @override
+  String get downloadAlbumArtistMetadataPrimaryOnly =>
+      'Album Artist metadata: Primary only';
+
+  @override
+  String get downloadAlbumArtistMetadataFull => 'Album Artist metadata: Full';
+
+  @override
+  String get trackConvertOriginal => 'Original';
+
+  @override
+  String get trackConvertOriginalQuality => 'Original quality';
+
+  @override
+  String get trackConvertLosslessSuffix => 'Lossless';
+
+  @override
+  String get trackConvertDithering => 'Dithering';
+
+  @override
+  String get trackConvertResampler => 'Resampler';
+
+  @override
+  String get trackConvertDitherNone => 'None';
+
+  @override
+  String get trackConvertDitherTriangular => 'TPDF';
+
+  @override
+  String get trackConvertDitherTriangularHp => 'Triangular HP';
+
+  @override
+  String get trackConvertResamplerSwr => 'SWR';
+
+  @override
+  String get trackConvertResamplerSoxr => 'SoXr';
+
+  @override
+  String get updateSeeReleaseNotes => 'See release notes for details.';
+
+  @override
+  String get unknownTitle => 'Unknown title';
+
+  @override
+  String get trackPlayNext => 'Play next';
+
+  @override
+  String get trackAddToQueue => 'Add to queue';
+
+  @override
+  String snackbarExtensionInstalledEnable(String extensionName) {
+    return '$extensionName installed. Enable it in Settings > Extensions';
+  }
+
+  @override
+  String snackbarExtensionUpdatedVersion(String extensionName, String version) {
+    return '$extensionName updated to v$version';
+  }
+
+  @override
+  String snackbarFailedToInstallNamed(String extensionName) {
+    return 'Failed to install $extensionName';
+  }
+
+  @override
+  String snackbarFailedToUpdateNamed(String extensionName) {
+    return 'Failed to update $extensionName';
+  }
+
+  @override
+  String get releaseTypeEp => 'EP';
+
+  @override
+  String get releaseTypeSingle => 'Single';
+
+  @override
+  String get trackCoverOnline => 'Online cover';
+
+  @override
+  String get regionCountryUS => 'United States';
+
+  @override
+  String get regionCountryGB => 'United Kingdom';
+
+  @override
+  String get regionCountryFR => 'France';
+
+  @override
+  String get regionCountryDE => 'Germany';
+
+  @override
+  String get regionCountryJP => 'Japan';
+
+  @override
+  String get regionCountryKR => 'South Korea';
+
+  @override
+  String get regionCountryIN => 'India';
+
+  @override
+  String get regionCountryID => 'Indonesia';
+
+  @override
+  String get regionCountryBR => 'Brazil';
+
+  @override
+  String get regionCountryMX => 'Mexico';
+
+  @override
+  String get regionCountryAU => 'Australia';
+
+  @override
+  String get regionCountryCA => 'Canada';
+
+  @override
+  String get regionCountryXK => 'Kosovo';
+
+  @override
+  String get extensionVerificationBrowserTitle => 'Verification browser';
+
+  @override
+  String get extensionVerificationBrowserSubtitleExternal =>
+      'Open challenges in the default browser first';
+
+  @override
+  String get extensionVerificationBrowserSubtitleInApp =>
+      'Open challenges in the in-app browser first';
+
+  @override
+  String get extensionVerificationBrowserExternal => 'External';
+
+  @override
+  String get extensionVerificationBrowserInApp => 'In-app';
+
+  @override
+  String get extensionVerificationHelpTitleManual =>
+      'Open verification manually';
+
+  @override
+  String get extensionVerificationHelpTitleWaiting =>
+      'Verification still waiting';
+
+  @override
+  String get extensionVerificationHelpMessageManual =>
+      'SpotiFLAC Mobile could not open the browser automatically. Open this link in your browser, or copy it manually.';
+
+  @override
+  String get extensionVerificationHelpMessageWaiting =>
+      'If the browser did not open, or verification finished but did not return to SpotiFLAC Mobile, open this link again or copy it manually.';
+
+  @override
+  String get extensionVerificationClose => 'Close';
+
+  @override
+  String get extensionVerificationCopyLink => 'Copy link';
+
+  @override
+  String get extensionVerificationLinkCopied => 'Verification link copied';
+
+  @override
+  String get extensionVerificationOpenBrowser => 'Open browser';
 }

lib/l10n/app_localizations_hi.dart

@@ -126,7 +126,7 @@ class AppLocalizationsHi extends AppLocalizations {
 
   @override
   String get optionsPrimaryProviderSubtitle =>
-      'Service used when searching by track name.';
+      'Service used for searching by track or album name';
 
   @override
   String optionsUsingExtension(String extensionName) {
@@ -142,7 +142,7 @@ class AppLocalizationsHi extends AppLocalizations {
 
   @override
   String get optionsSwitchBack =>
-      'Tap Deezer or Spotify to switch back from extension';
+      'Choose the default search provider to switch back from an extension';
 
   @override
   String get optionsAutoFallback => 'Auto Fallback';
@@ -155,17 +155,19 @@ class AppLocalizationsHi extends AppLocalizations {
   String get optionsUseExtensionProviders => 'Use Extension Providers';
 
   @override
-  String get optionsUseExtensionProvidersOn => 'Extensions will be tried first';
+  String get optionsUseExtensionProvidersOn =>
+      'Extension providers are enabled';
 
   @override
-  String get optionsUseExtensionProvidersOff => 'Using built-in providers only';
+  String get optionsUseExtensionProvidersOff =>
+      'Extension providers are required';
 
   @override
   String get optionsEmbedLyrics => 'Embed Lyrics';
 
   @override
   String get optionsEmbedLyricsSubtitle =>
-      'Embed synced lyrics into FLAC files';
+      'Save synced lyrics alongside your downloaded tracks';
 
   @override
   String get optionsMaxQualityCover => 'Max Quality Cover';
@@ -185,6 +187,43 @@ class AppLocalizationsHi extends AppLocalizations {
   String get optionsReplayGainSubtitleOff =>
       'Disabled: no loudness normalization tags';
 
+  @override
+  String get trackReplayGain => 'Rescan ReplayGain';
+
+  @override
+  String get trackReplayGainSubtitle =>
+      'Analyze loudness and write ReplayGain tags';
+
+  @override
+  String get trackReplayGainScanning => 'Analyzing loudness...';
+
+  @override
+  String get trackReplayGainSuccess => 'ReplayGain tags added';
+
+  @override
+  String get trackReplayGainFailed => 'Failed to add ReplayGain tags';
+
+  @override
+  String selectionReplayGainCount(int count) {
+    return 'ReplayGain ($count)';
+  }
+
+  @override
+  String get replayGainBatchConfirmTitle => 'Add ReplayGain';
+
+  @override
+  String replayGainBatchConfirmMessage(int count) {
+    return 'Analyze loudness and write ReplayGain tags to $count track(s)?';
+  }
+
+  @override
+  String get replayGainBatchAnalyzing => 'Analyzing ReplayGain...';
+
+  @override
+  String replayGainBatchSuccess(int success, int total) {
+    return 'ReplayGain added to $success of $total tracks';
+  }
+
   @override
   String get optionsArtistTagMode => 'Artist Tag Mode';
 
@@ -206,21 +245,6 @@ class AppLocalizationsHi extends AppLocalizations {
   String get optionsArtistTagModeSplitVorbisSubtitle =>
       'Write one artist tag per artist for FLAC and Opus; MP3 and M4A stay joined.';
 
-  @override
-  String get optionsConcurrentDownloads => 'Concurrent Downloads';
-
-  @override
-  String get optionsConcurrentSequential => 'Sequential (1 at a time)';
-
-  @override
-  String optionsConcurrentParallel(int count) {
-    return '$count parallel downloads';
-  }
-
-  @override
-  String get optionsConcurrentWarning =>
-      'Parallel downloads may trigger rate limiting';
-
   @override
   String get optionsExtensionStore => 'Extension Repo';
 
@@ -385,11 +409,11 @@ class AppLocalizationsHi extends AppLocalizations {
 
   @override
   String get aboutBinimumDesc =>
-      'The creator of QQDL & HiFi API. Without this API, Tidal downloads wouldn\'t exist!';
+      'The creator of QQDL & HiFi API. This project helped shape lossless download support.';
 
   @override
   String get aboutSachinsenalDesc =>
-      'The original HiFi project creator. The foundation of Tidal integration!';
+      'The original HiFi project creator. A foundation for lossless-source integration.';
 
   @override
   String get aboutSjdonadoDesc =>
@@ -579,6 +603,15 @@ class AppLocalizationsHi extends AppLocalizations {
   @override
   String get dialogDownload => 'Download';
 
+  @override
+  String get previewPlay => 'Play preview';
+
+  @override
+  String get previewStop => 'Stop preview';
+
+  @override
+  String get previewUnavailable => 'Preview unavailable';
+
   @override
   String get dialogDiscard => 'Discard';
 
@@ -953,7 +986,7 @@ class AppLocalizationsHi extends AppLocalizations {
       'Only enabled extensions with download-provider capability are listed here.';
 
   @override
-  String get providerBuiltIn => 'Built-in';
+  String get providerBuiltIn => 'Legacy';
 
   @override
   String get providerExtension => 'Extension';
@@ -1121,10 +1154,10 @@ class AppLocalizationsHi extends AppLocalizations {
   String get settingsAppearanceSubtitle => 'Theme, colors, display';
 
   @override
-  String get settingsDownloadSubtitle => 'Service, quality, filename format';
+  String get settingsDownloadSubtitle => 'Service, quality, fallback';
 
   @override
-  String get settingsOptionsSubtitle => 'Fallback, lyrics, cover art, updates';
+  String get settingsOptionsSubtitle => 'Fallback, metadata, lyrics, cover art';
 
   @override
   String get settingsExtensionsSubtitle => 'Manage download providers';
@@ -1346,10 +1379,11 @@ class AppLocalizationsHi extends AppLocalizations {
   String get storeEmptyNoResults => 'No extensions found';
 
   @override
-  String get extensionDefaultProvider => 'Default (Deezer)';
+  String get extensionDefaultProvider => 'Default Search';
 
   @override
-  String get extensionDefaultProviderSubtitle => 'Use built-in search';
+  String get extensionDefaultProviderSubtitle =>
+      'Use the default metadata search';
 
   @override
   String get extensionAuthor => 'Author';
@@ -1523,7 +1557,7 @@ class AppLocalizationsHi extends AppLocalizations {
 
   @override
   String get downloadLossy320FormatDesc =>
-      'Choose the output format for Tidal 320kbps lossy downloads. The original AAC stream will be converted to your selected format.';
+      'Choose the output format for 320kbps lossy downloads. The original stream will be converted to your selected format when needed.';
 
   @override
   String get downloadLossyMp3 => 'MP3 320kbps';
@@ -1567,6 +1601,10 @@ class AppLocalizationsHi extends AppLocalizations {
   @override
   String get downloadAlbumFolderStructure => 'Album Folder Structure';
 
+  @override
+  String get albumFolderStructureDescription =>
+      'Choose how album folders are structured';
+
   @override
   String get downloadUseAlbumArtistForFolders => 'Use Album Artist for folders';
 
@@ -2093,7 +2131,7 @@ class AppLocalizationsHi extends AppLocalizations {
 
   @override
   String get tutorialWelcomeTip2 =>
-      'Get FLAC quality audio from Tidal, Qobuz, or Deezer';
+      'Get FLAC quality audio from installed download extensions';
 
   @override
   String get tutorialWelcomeTip3 =>
@@ -2423,7 +2461,7 @@ class AppLocalizationsHi extends AppLocalizations {
 
   @override
   String get trackConvertFormatSubtitle =>
-      'Convert to MP3, Opus, ALAC, or FLAC';
+      'Convert to AAC/M4A, MP3, Opus, ALAC, or FLAC';
 
   @override
   String get trackConvertTitle => 'Convert Audio';
@@ -2776,14 +2814,14 @@ class AppLocalizationsHi extends AppLocalizations {
 
   @override
   String get downloadUseAlbumArtistForFoldersAlbumSubtitle =>
-      'Artist folders use Album Artist when available';
+      'Folder named after Album Artist tag';
 
   @override
   String get downloadUseAlbumArtistForFoldersTrackSubtitle =>
-      'Artist folders use Track Artist only';
+      'Folder named after Track Artist tag';
 
   @override
-  String get lyricsProvidersTitle => 'Lyrics Providers';
+  String get lyricsProvidersTitle => 'Lyrics Provider Priority';
 
   @override
   String get lyricsProvidersDescription =>
@@ -2791,7 +2829,7 @@ class AppLocalizationsHi extends AppLocalizations {
 
   @override
   String get lyricsProvidersInfoText =>
-      'Extension lyrics providers always run before built-in providers. At least one provider must remain enabled.';
+      'Extension lyrics providers run before built-in lyrics providers. At least one provider must remain enabled.';
 
   @override
   String lyricsProvidersEnabledSection(int count) {
@@ -2833,6 +2871,10 @@ class AppLocalizationsHi extends AppLocalizations {
   String get lyricsProviderQqMusicDesc =>
       'QQ Music (good for Chinese songs, via proxy)';
 
+  @override
+  String get lyricsProviderLyricsPlusDesc =>
+      'Word-by-word karaoke lyrics (Apple/Musixmatch/Spotify/QQ, via proxy)';
+
   @override
   String get lyricsProviderExtensionDesc => 'Extension provider';
 
@@ -2851,10 +2893,168 @@ class AppLocalizationsHi extends AppLocalizations {
   String get safMigrationSuccess => 'Download folder updated to SAF mode';
 
   @override
-  String get settingsDonate => 'Donate';
+  String get settingsDonate => 'Support Development';
 
   @override
-  String get settingsDonateSubtitle => 'Support SpotiFLAC-Mobile development';
+  String get settingsDonateSubtitle => 'Buy the developer a coffee';
+
+  @override
+  String get settingsBackup => 'Backup & Restore';
+
+  @override
+  String get settingsBackupSubtitle =>
+      'Move your library, history and settings to a new device';
+
+  @override
+  String get backupTitle => 'Backup & Restore';
+
+  @override
+  String get backupExportSectionTitle => 'Create backup';
+
+  @override
+  String get backupExportSectionDescription =>
+      'Save your settings, download history, liked tracks, wishlist, favorite artists and playlists into a single file you can keep or move to another phone.';
+
+  @override
+  String get backupExportButton => 'Create backup file';
+
+  @override
+  String get backupImportSectionTitle => 'Restore backup';
+
+  @override
+  String get backupImportSectionDescription =>
+      'Pick a backup file to restore your data. This replaces the current settings, history and library on this device.';
+
+  @override
+  String get backupImportButton => 'Choose backup file';
+
+  @override
+  String get backupCreating => 'Creating backup...';
+
+  @override
+  String get backupCreated => 'Backup created';
+
+  @override
+  String get backupCreateFailed => 'Failed to create backup';
+
+  @override
+  String get backupEmpty => 'There is nothing to back up yet';
+
+  @override
+  String get backupRestoreConfirmTitle => 'Restore this backup?';
+
+  @override
+  String get backupRestoreConfirmMessage =>
+      'This will replace your current settings, download history, liked tracks, wishlist and playlists with the contents of the backup. This cannot be undone.';
+
+  @override
+  String get backupRestoreConfirmButton => 'Restore';
+
+  @override
+  String get backupRestoring => 'Restoring backup...';
+
+  @override
+  String get backupRestored => 'Backup restored successfully';
+
+  @override
+  String get backupRestoreFailed => 'Failed to restore backup';
+
+  @override
+  String get backupInvalidFile => 'This file is not a valid SpotiFLAC backup';
+
+  @override
+  String get backupRestoreRestartHint =>
+      'Restart the app to make sure every change is applied.';
+
+  @override
+  String get backupContentsTitle => 'Backup contents';
+
+  @override
+  String get backupContentsSettings => 'App settings';
+
+  @override
+  String backupContentsHistory(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'items',
+      one: 'item',
+    );
+    return '$count history $_temp0';
+  }
+
+  @override
+  String backupContentsLiked(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return '$count liked $_temp0';
+  }
+
+  @override
+  String backupContentsWishlist(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return '$count wishlist $_temp0';
+  }
+
+  @override
+  String backupContentsPlaylists(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count playlists',
+      one: '1 playlist',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String backupContentsArtists(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count favorite artists',
+      one: '1 favorite artist',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String backupContentsExtensions(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count extensions',
+      one: '1 extension',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String get backupIncludeSecrets => 'Include extension credentials';
+
+  @override
+  String get backupIncludeSecretsDescription =>
+      'Tokens and API keys from extensions will be saved into the backup file. Keep the file private. When off, you re-enter them after restoring.';
+
+  @override
+  String backupExtensionsRestoreFailed(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'extensions',
+      one: 'extension',
+    );
+    return '$count $_temp0 could not be reinstalled. Install them manually from the store.';
+  }
 
   @override
   String get tooltipLoveAll => 'Love All';
@@ -2914,20 +3114,20 @@ class AppLocalizationsHi extends AppLocalizations {
 
   @override
   String get downloadLocationSubtitle =>
-      'Choose storage mode for downloaded files.';
+      'Choose where to save your downloaded tracks';
 
   @override
-  String get storageModeAppFolder => 'App folder (non-SAF)';
+  String get storageModeAppFolder => 'App Folder (Recommended)';
 
   @override
-  String get storageModeAppFolderSubtitle => 'Use default Music/SpotiFLAC path';
+  String get storageModeAppFolderSubtitle =>
+      'Saves to Music/SpotiFLAC by default';
 
   @override
-  String get storageModeSaf => 'SAF folder';
+  String get storageModeSaf => 'Custom Folder (SAF)';
 
   @override
-  String get storageModeSafSubtitle =>
-      'Pick folder via Android Storage Access Framework';
+  String get storageModeSafSubtitle => 'Pick any folder, including SD card';
 
   @override
   String downloadFilenameDescription(
@@ -2939,62 +3139,73 @@ class AppLocalizationsHi extends AppLocalizations {
     Object track,
     Object year,
   ) {
-    return 'Customize how your files are named.';
+    return 'Use $artist, $title, $album, $track, $year, $date, $disc as placeholders.';
   }
 
   @override
   String get downloadFilenameInsertTag => 'Tap to insert tag:';
 
   @override
-  String get downloadSeparateSinglesEnabled => 'Albums/ and Singles/ folders';
+  String get downloadSeparateSinglesEnabled =>
+      'Singles and EPs saved in a separate folder';
 
   @override
-  String get downloadSeparateSinglesDisabled => 'All files in same structure';
+  String get downloadSeparateSinglesDisabled =>
+      'Singles and albums saved in the same folder';
 
   @override
   String get downloadArtistNameFilters => 'Artist Name Filters';
 
   @override
-  String get downloadCreatePlaylistSourceFolder =>
-      'Create playlist source folder';
+  String get downloadCreatePlaylistSourceFolder => 'Playlist Source Folder';
 
   @override
   String get downloadCreatePlaylistSourceFolderEnabled =>
-      'Playlist downloads use Playlist/ plus your normal folder structure.';
+      'A subfolder is created for each playlist';
 
   @override
   String get downloadCreatePlaylistSourceFolderDisabled =>
-      'Playlist downloads use the normal folder structure only.';
+      'All tracks saved directly to download folder';
 
   @override
   String get downloadCreatePlaylistSourceFolderRedundant =>
-      'By Playlist already places downloads inside a playlist folder.';
+      'Handled by folder organization setting';
 
   @override
   String get downloadSongLinkRegion => 'SongLink Region';
 
   @override
-  String get downloadNetworkCompatibilityMode => 'Network compatibility mode';
+  String get downloadNetworkCompatibilityMode => 'Network Compatibility Mode';
 
   @override
   String get downloadNetworkCompatibilityModeEnabled =>
-      'Enabled: try HTTP + accept invalid TLS certificates (unsafe)';
+      'Using legacy TLS settings for older networks';
 
   @override
   String get downloadNetworkCompatibilityModeDisabled =>
-      'Off: strict HTTPS certificate validation (recommended)';
+      'Using standard network settings';
+
+  @override
+  String get downloadAllowLocalNetwork => 'Allow Local Network Access';
+
+  @override
+  String get downloadAllowLocalNetworkEnabled =>
+      'Requests to local/private addresses are allowed (for local proxy or custom DNS)';
+
+  @override
+  String get downloadAllowLocalNetworkDisabled =>
+      'Local/private addresses are blocked for security';
 
   @override
   String get downloadSelectServiceToEnable =>
-      'Select a built-in service to enable';
+      'Select a provider with quality options to enable this option';
 
   @override
   String get downloadSelectTidalQobuz =>
-      'Select Tidal or Qobuz above to configure quality';
+      'Select a provider with quality options to choose audio quality';
 
   @override
-  String get downloadEmbedLyricsDisabled =>
-      'Disabled while Embed Metadata is turned off';
+  String get downloadEmbedLyricsDisabled => 'Enable metadata embedding first';
 
   @override
   String get downloadNeteaseIncludeTranslation =>
@@ -3002,11 +3213,11 @@ class AppLocalizationsHi extends AppLocalizations {
 
   @override
   String get downloadNeteaseIncludeTranslationEnabled =>
-      'Append translated lyrics when available';
+      'Chinese translation lines included';
 
   @override
   String get downloadNeteaseIncludeTranslationDisabled =>
-      'Use original lyrics only';
+      'Original lyrics only';
 
   @override
   String get downloadNeteaseIncludeRomanization =>
@@ -3014,21 +3225,21 @@ class AppLocalizationsHi extends AppLocalizations {
 
   @override
   String get downloadNeteaseIncludeRomanizationEnabled =>
-      'Append romanized lyrics when available';
+      'Romanization lines included';
 
   @override
-  String get downloadNeteaseIncludeRomanizationDisabled => 'Disabled';
+  String get downloadNeteaseIncludeRomanizationDisabled => 'No romanization';
 
   @override
-  String get downloadAppleQqMultiPerson => 'Apple/QQ Multi-Person Word-by-Word';
+  String get downloadAppleQqMultiPerson => 'Apple / QQ: Multi-Person Lyrics';
 
   @override
   String get downloadAppleQqMultiPersonEnabled =>
-      'Enable v1/v2 speaker and [bg:] tags';
+      'Speaker labels included for duets and group tracks';
 
   @override
   String get downloadAppleQqMultiPersonDisabled =>
-      'Simplified word-by-word formatting';
+      'Standard lyrics without speaker labels';
 
   @override
   String get downloadAppleElrcWordSync => 'Apple Music eLRC Word Sync';
@@ -3045,46 +3256,45 @@ class AppLocalizationsHi extends AppLocalizations {
   String get downloadMusixmatchLanguage => 'Musixmatch Language';
 
   @override
-  String get downloadMusixmatchLanguageAuto => 'Auto (original)';
+  String get downloadMusixmatchLanguageAuto => 'Auto (original language)';
 
   @override
-  String get downloadFilterContributing =>
-      'Filter contributing artists in Album Artist';
+  String get downloadFilterContributing => 'Filter Contributing Artists';
 
   @override
   String get downloadFilterContributingEnabled =>
-      'Album Artist metadata uses primary artist only';
+      'Contributing artists removed from Album Artist folder name';
 
   @override
   String get downloadFilterContributingDisabled =>
-      'Keep full Album Artist metadata value';
+      'Full Album Artist string used';
 
   @override
-  String get downloadProvidersNoneEnabled => 'None enabled';
+  String get downloadProvidersNoneEnabled => 'No providers enabled';
 
   @override
   String get downloadMusixmatchLanguageCode => 'Language code';
 
   @override
-  String get downloadMusixmatchLanguageHint => 'auto / en / es / ja';
+  String get downloadMusixmatchLanguageHint => 'e.g. en, de, ja';
 
   @override
   String get downloadMusixmatchLanguageDesc =>
-      'Set preferred language code (example: en, es, ja). Leave empty for auto.';
+      'Enter a BCP-47 language code (e.g. en, de, ja) to request translated lyrics from Musixmatch.';
 
   @override
   String get downloadMusixmatchAuto => 'Auto';
 
   @override
-  String get downloadNetworkAnySubtitle => 'WiFi + Mobile Data';
+  String get downloadNetworkAnySubtitle => 'Use WiFi or mobile data';
 
   @override
   String get downloadNetworkWifiOnlySubtitle =>
-      'Pause downloads on mobile data';
+      'Downloads pause when on mobile data';
 
   @override
   String get downloadSongLinkRegionDesc =>
-      'Used as userCountry for SongLink API lookup.';
+      'Region used when resolving track links via SongLink. Choose the country where your streaming services are available.';
 
   @override
   String get snackbarUnsupportedAudioFormat => 'Unsupported audio format';
@@ -3470,7 +3680,13 @@ class AppLocalizationsHi extends AppLocalizations {
 
   @override
   String notifTracksDownloadedSuccess(int count) {
-    return '$count tracks downloaded successfully';
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count tracks downloaded successfully',
+      one: '1 track downloaded successfully',
+    );
+    return '$_temp0';
   }
 
   @override
@@ -4240,4 +4456,318 @@ class AppLocalizationsHi extends AppLocalizations {
   String shareSheetLinkCopied(Object service) {
     return '$service link copied';
   }
+
+  @override
+  String get libraryPlayback => 'Playback';
+
+  @override
+  String get libraryExternalPlayer => 'External player';
+
+  @override
+  String get libraryExternalPlayerSubtitle =>
+      'Recommended for listening, best quality, gapless playback, EQ, and wider format support';
+
+  @override
+  String get libraryBuiltInPreviewPlayer => 'Built-in preview player';
+
+  @override
+  String get libraryBuiltInPreviewPlayerSubtitle =>
+      'Only for quick local previews inside SpotiFLAC Mobile, not recommended for regular listening';
+
+  @override
+  String get libraryBuiltInPlayerInfo =>
+      'The built-in player is a preview tool for checking local tracks quickly. Use an external music player for actual listening.';
+
+  @override
+  String get nowPlayingTitle => 'Now Playing';
+
+  @override
+  String get nowPlayingNothingPlaying => 'Nothing is playing';
+
+  @override
+  String get nowPlayingMinimize => 'Minimize';
+
+  @override
+  String get nowPlayingUpNext => 'Up next';
+
+  @override
+  String get nowPlayingDetails => 'Details';
+
+  @override
+  String get nowPlayingOpenInExternalPlayer => 'Open in external player';
+
+  @override
+  String get nowPlayingTabPlayer => 'Player';
+
+  @override
+  String get nowPlayingTabLyrics => 'Lyrics';
+
+  @override
+  String get nowPlayingNoLyrics => 'No lyrics in this file';
+
+  @override
+  String get nowPlayingLibraryEmpty => 'Your library is empty';
+
+  @override
+  String nowPlayingShuffleLibraryFailed(String error) {
+    return 'Could not shuffle library: $error';
+  }
+
+  @override
+  String get nowPlayingShuffleOn => 'Shuffle on';
+
+  @override
+  String get nowPlayingPlayInOrder => 'Play in order';
+
+  @override
+  String get nowPlayingShuffleLibrary => 'Shuffle library';
+
+  @override
+  String get nowPlayingQueueEmpty => 'Queue is empty';
+
+  @override
+  String get nowPlayingNoMetadata => 'No metadata available';
+
+  @override
+  String get announcementUnableToOpenLink =>
+      'Unable to open link. Please try again.';
+
+  @override
+  String trackConvertLosslessOutputWithCap(String quality) {
+    return 'Lossless output with $quality cap';
+  }
+
+  @override
+  String trackConvertConfirmMessageLosslessCapped(
+    String sourceFormat,
+    String targetFormat,
+    String quality,
+  ) {
+    return 'Convert from $sourceFormat to $targetFormat ($quality)?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original file will be deleted after conversion.';
+  }
+
+  @override
+  String selectionBatchConvertConfirmMessageLosslessCapped(
+    int count,
+    String format,
+    String quality,
+  ) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return 'Convert $count $_temp0 to $format ($quality)?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original files will be deleted after conversion.';
+  }
+
+  @override
+  String trackConvertActionLabelLossless(
+    String sourceFormat,
+    String targetFormat,
+    String quality,
+  ) {
+    return '$sourceFormat → $targetFormat ($quality)';
+  }
+
+  @override
+  String trackConvertActionLabelLossy(
+    String sourceFormat,
+    String targetFormat,
+    String bitrate,
+  ) {
+    return '$sourceFormat → $targetFormat @ $bitrate';
+  }
+
+  @override
+  String get aboutPaxsenixSubtitle =>
+      'Lyrics proxy for Musixmatch, Netease, Apple Music, QQ Music, Spotify, Deezer, YouTube, Kugou, and Genius';
+
+  @override
+  String get snackbarPlayingNext => 'Playing next';
+
+  @override
+  String get snackbarAddedToQueueGeneric => 'Added to queue';
+
+  @override
+  String selectionDeletePlaylistsCount(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'playlists',
+      one: 'playlist',
+    );
+    return 'Delete $count $_temp0';
+  }
+
+  @override
+  String get actionShuffle => 'Shuffle';
+
+  @override
+  String get downloadPrimaryArtistOnlyOn => 'Primary only: On';
+
+  @override
+  String get downloadPrimaryArtistOnlyOff => 'Primary only: Off';
+
+  @override
+  String get downloadAlbumArtistMetadataPrimaryOnly =>
+      'Album Artist metadata: Primary only';
+
+  @override
+  String get downloadAlbumArtistMetadataFull => 'Album Artist metadata: Full';
+
+  @override
+  String get trackConvertOriginal => 'Original';
+
+  @override
+  String get trackConvertOriginalQuality => 'Original quality';
+
+  @override
+  String get trackConvertLosslessSuffix => 'Lossless';
+
+  @override
+  String get trackConvertDithering => 'Dithering';
+
+  @override
+  String get trackConvertResampler => 'Resampler';
+
+  @override
+  String get trackConvertDitherNone => 'None';
+
+  @override
+  String get trackConvertDitherTriangular => 'TPDF';
+
+  @override
+  String get trackConvertDitherTriangularHp => 'Triangular HP';
+
+  @override
+  String get trackConvertResamplerSwr => 'SWR';
+
+  @override
+  String get trackConvertResamplerSoxr => 'SoXr';
+
+  @override
+  String get updateSeeReleaseNotes => 'See release notes for details.';
+
+  @override
+  String get unknownTitle => 'Unknown title';
+
+  @override
+  String get trackPlayNext => 'Play next';
+
+  @override
+  String get trackAddToQueue => 'Add to queue';
+
+  @override
+  String snackbarExtensionInstalledEnable(String extensionName) {
+    return '$extensionName installed. Enable it in Settings > Extensions';
+  }
+
+  @override
+  String snackbarExtensionUpdatedVersion(String extensionName, String version) {
+    return '$extensionName updated to v$version';
+  }
+
+  @override
+  String snackbarFailedToInstallNamed(String extensionName) {
+    return 'Failed to install $extensionName';
+  }
+
+  @override
+  String snackbarFailedToUpdateNamed(String extensionName) {
+    return 'Failed to update $extensionName';
+  }
+
+  @override
+  String get releaseTypeEp => 'EP';
+
+  @override
+  String get releaseTypeSingle => 'Single';
+
+  @override
+  String get trackCoverOnline => 'Online cover';
+
+  @override
+  String get regionCountryUS => 'United States';
+
+  @override
+  String get regionCountryGB => 'United Kingdom';
+
+  @override
+  String get regionCountryFR => 'France';
+
+  @override
+  String get regionCountryDE => 'Germany';
+
+  @override
+  String get regionCountryJP => 'Japan';
+
+  @override
+  String get regionCountryKR => 'South Korea';
+
+  @override
+  String get regionCountryIN => 'India';
+
+  @override
+  String get regionCountryID => 'Indonesia';
+
+  @override
+  String get regionCountryBR => 'Brazil';
+
+  @override
+  String get regionCountryMX => 'Mexico';
+
+  @override
+  String get regionCountryAU => 'Australia';
+
+  @override
+  String get regionCountryCA => 'Canada';
+
+  @override
+  String get regionCountryXK => 'Kosovo';
+
+  @override
+  String get extensionVerificationBrowserTitle => 'Verification browser';
+
+  @override
+  String get extensionVerificationBrowserSubtitleExternal =>
+      'Open challenges in the default browser first';
+
+  @override
+  String get extensionVerificationBrowserSubtitleInApp =>
+      'Open challenges in the in-app browser first';
+
+  @override
+  String get extensionVerificationBrowserExternal => 'External';
+
+  @override
+  String get extensionVerificationBrowserInApp => 'In-app';
+
+  @override
+  String get extensionVerificationHelpTitleManual =>
+      'Open verification manually';
+
+  @override
+  String get extensionVerificationHelpTitleWaiting =>
+      'Verification still waiting';
+
+  @override
+  String get extensionVerificationHelpMessageManual =>
+      'SpotiFLAC Mobile could not open the browser automatically. Open this link in your browser, or copy it manually.';
+
+  @override
+  String get extensionVerificationHelpMessageWaiting =>
+      'If the browser did not open, or verification finished but did not return to SpotiFLAC Mobile, open this link again or copy it manually.';
+
+  @override
+  String get extensionVerificationClose => 'Close';
+
+  @override
+  String get extensionVerificationCopyLink => 'Copy link';
+
+  @override
+  String get extensionVerificationLinkCopied => 'Verification link copied';
+
+  @override
+  String get extensionVerificationOpenBrowser => 'Open browser';
 }

lib/l10n/app_localizations_ja.dart

@@ -126,7 +126,7 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get optionsPrimaryProviderSubtitle =>
-      'Service used when searching by track name.';
+      'Service used for searching by track or album name';
 
   @override
   String optionsUsingExtension(String extensionName) {
@@ -142,7 +142,7 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get optionsSwitchBack =>
-      'Tap Deezer or Spotify to switch back from extension';
+      'Choose the default search provider to switch back from an extension';
 
   @override
   String get optionsAutoFallback => 'Auto Fallback';
@@ -155,16 +155,19 @@ class AppLocalizationsJa extends AppLocalizations {
   String get optionsUseExtensionProviders => '拡張のプロバイダーを使用する';
 
   @override
-  String get optionsUseExtensionProvidersOn => '最初に拡張で試みます';
+  String get optionsUseExtensionProvidersOn =>
+      'Extension providers are enabled';
 
   @override
-  String get optionsUseExtensionProvidersOff => '内蔵のプロバイダーのみを使用する';
+  String get optionsUseExtensionProvidersOff =>
+      'Extension providers are required';
 
   @override
   String get optionsEmbedLyrics => '歌詞を埋め込む';
 
   @override
-  String get optionsEmbedLyricsSubtitle => '同期する歌詞を FLAC ファイルに埋め込む';
+  String get optionsEmbedLyricsSubtitle =>
+      'Save synced lyrics alongside your downloaded tracks';
 
   @override
   String get optionsMaxQualityCover => '最大品質のカバー';
@@ -183,6 +186,43 @@ class AppLocalizationsJa extends AppLocalizations {
   String get optionsReplayGainSubtitleOff =>
       'Disabled: no loudness normalization tags';
 
+  @override
+  String get trackReplayGain => 'Rescan ReplayGain';
+
+  @override
+  String get trackReplayGainSubtitle =>
+      'Analyze loudness and write ReplayGain tags';
+
+  @override
+  String get trackReplayGainScanning => 'Analyzing loudness...';
+
+  @override
+  String get trackReplayGainSuccess => 'ReplayGain tags added';
+
+  @override
+  String get trackReplayGainFailed => 'Failed to add ReplayGain tags';
+
+  @override
+  String selectionReplayGainCount(int count) {
+    return 'ReplayGain ($count)';
+  }
+
+  @override
+  String get replayGainBatchConfirmTitle => 'Add ReplayGain';
+
+  @override
+  String replayGainBatchConfirmMessage(int count) {
+    return 'Analyze loudness and write ReplayGain tags to $count track(s)?';
+  }
+
+  @override
+  String get replayGainBatchAnalyzing => 'Analyzing ReplayGain...';
+
+  @override
+  String replayGainBatchSuccess(int success, int total) {
+    return 'ReplayGain added to $success of $total tracks';
+  }
+
   @override
   String get optionsArtistTagMode => 'Artist Tag Mode';
 
@@ -204,21 +244,6 @@ class AppLocalizationsJa extends AppLocalizations {
   String get optionsArtistTagModeSplitVorbisSubtitle =>
       'Write one artist tag per artist for FLAC and Opus; MP3 and M4A stay joined.';
 
-  @override
-  String get optionsConcurrentDownloads => '同時ダウンロード';
-
-  @override
-  String get optionsConcurrentSequential => 'Sequential (1 at a time)';
-
-  @override
-  String optionsConcurrentParallel(int count) {
-    return '$count 件の分割ダウンロード';
-  }
-
-  @override
-  String get optionsConcurrentWarning =>
-      'Parallel downloads may trigger rate limiting';
-
   @override
   String get optionsExtensionStore => 'Extension Repo';
 
@@ -381,11 +406,11 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get aboutBinimumDesc =>
-      'The creator of QQDL & HiFi API. Without this API, Tidal downloads wouldn\'t exist!';
+      'The creator of QQDL & HiFi API. This project helped shape lossless download support.';
 
   @override
   String get aboutSachinsenalDesc =>
-      'The original HiFi project creator. The foundation of Tidal integration!';
+      'The original HiFi project creator. A foundation for lossless-source integration.';
 
   @override
   String get aboutSjdonadoDesc =>
@@ -575,6 +600,15 @@ class AppLocalizationsJa extends AppLocalizations {
   @override
   String get dialogDownload => 'Download';
 
+  @override
+  String get previewPlay => 'Play preview';
+
+  @override
+  String get previewStop => 'Stop preview';
+
+  @override
+  String get previewUnavailable => 'Preview unavailable';
+
   @override
   String get dialogDiscard => '破棄';
 
@@ -947,7 +981,7 @@ class AppLocalizationsJa extends AppLocalizations {
       'Only enabled extensions with download-provider capability are listed here.';
 
   @override
-  String get providerBuiltIn => '内蔵';
+  String get providerBuiltIn => 'Legacy';
 
   @override
   String get providerExtension => '拡張';
@@ -1115,10 +1149,10 @@ class AppLocalizationsJa extends AppLocalizations {
   String get settingsAppearanceSubtitle => 'テーマ、カラー、画面';
 
   @override
-  String get settingsDownloadSubtitle => 'サービス、品質、ファイル名、形式';
+  String get settingsDownloadSubtitle => 'Service, quality, fallback';
 
   @override
-  String get settingsOptionsSubtitle => 'Fallback, lyrics, cover art, updates';
+  String get settingsOptionsSubtitle => 'Fallback, metadata, lyrics, cover art';
 
   @override
   String get settingsExtensionsSubtitle => 'ダウンロードプロバイダーを管理';
@@ -1340,10 +1374,11 @@ class AppLocalizationsJa extends AppLocalizations {
   String get storeEmptyNoResults => 'No extensions found';
 
   @override
-  String get extensionDefaultProvider => 'Default (Deezer)';
+  String get extensionDefaultProvider => 'Default Search';
 
   @override
-  String get extensionDefaultProviderSubtitle => '内蔵の検索を使用する';
+  String get extensionDefaultProviderSubtitle =>
+      'Use the default metadata search';
 
   @override
   String get extensionAuthor => '作者';
@@ -1513,7 +1548,7 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get downloadLossy320FormatDesc =>
-      'Choose the output format for Tidal 320kbps lossy downloads. The original AAC stream will be converted to your selected format.';
+      'Choose the output format for 320kbps lossy downloads. The original stream will be converted to your selected format when needed.';
 
   @override
   String get downloadLossyMp3 => 'MP3 320kbps';
@@ -1556,6 +1591,9 @@ class AppLocalizationsJa extends AppLocalizations {
   @override
   String get downloadAlbumFolderStructure => 'アルバムフォルダの構造';
 
+  @override
+  String get albumFolderStructureDescription => 'アルバムフォルダの構成を選択';
+
   @override
   String get downloadUseAlbumArtistForFolders => 'Use Album Artist for folders';
 
@@ -2080,7 +2118,7 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get tutorialWelcomeTip2 =>
-      'Get FLAC quality audio from Tidal, Qobuz, or Deezer';
+      'Get FLAC quality audio from installed download extensions';
 
   @override
   String get tutorialWelcomeTip3 =>
@@ -2410,7 +2448,7 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get trackConvertFormatSubtitle =>
-      'Convert to MP3, Opus, ALAC, or FLAC';
+      'Convert to AAC/M4A, MP3, Opus, ALAC, or FLAC';
 
   @override
   String get trackConvertTitle => 'オーディオを変換';
@@ -2763,14 +2801,14 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get downloadUseAlbumArtistForFoldersAlbumSubtitle =>
-      'Artist folders use Album Artist when available';
+      'Folder named after Album Artist tag';
 
   @override
   String get downloadUseAlbumArtistForFoldersTrackSubtitle =>
-      'Artist folders use Track Artist only';
+      'Folder named after Track Artist tag';
 
   @override
-  String get lyricsProvidersTitle => 'Lyrics Providers';
+  String get lyricsProvidersTitle => 'Lyrics Provider Priority';
 
   @override
   String get lyricsProvidersDescription =>
@@ -2778,7 +2816,7 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get lyricsProvidersInfoText =>
-      'Extension lyrics providers always run before built-in providers. At least one provider must remain enabled.';
+      'Extension lyrics providers run before built-in lyrics providers. At least one provider must remain enabled.';
 
   @override
   String lyricsProvidersEnabledSection(int count) {
@@ -2820,6 +2858,10 @@ class AppLocalizationsJa extends AppLocalizations {
   String get lyricsProviderQqMusicDesc =>
       'QQ Music (good for Chinese songs, via proxy)';
 
+  @override
+  String get lyricsProviderLyricsPlusDesc =>
+      'Word-by-word karaoke lyrics (Apple/Musixmatch/Spotify/QQ, via proxy)';
+
   @override
   String get lyricsProviderExtensionDesc => 'Extension provider';
 
@@ -2838,10 +2880,168 @@ class AppLocalizationsJa extends AppLocalizations {
   String get safMigrationSuccess => 'Download folder updated to SAF mode';
 
   @override
-  String get settingsDonate => 'Donate';
+  String get settingsDonate => 'Support Development';
 
   @override
-  String get settingsDonateSubtitle => 'Support SpotiFLAC-Mobile development';
+  String get settingsDonateSubtitle => 'Buy the developer a coffee';
+
+  @override
+  String get settingsBackup => 'Backup & Restore';
+
+  @override
+  String get settingsBackupSubtitle =>
+      'Move your library, history and settings to a new device';
+
+  @override
+  String get backupTitle => 'Backup & Restore';
+
+  @override
+  String get backupExportSectionTitle => 'Create backup';
+
+  @override
+  String get backupExportSectionDescription =>
+      'Save your settings, download history, liked tracks, wishlist, favorite artists and playlists into a single file you can keep or move to another phone.';
+
+  @override
+  String get backupExportButton => 'Create backup file';
+
+  @override
+  String get backupImportSectionTitle => 'Restore backup';
+
+  @override
+  String get backupImportSectionDescription =>
+      'Pick a backup file to restore your data. This replaces the current settings, history and library on this device.';
+
+  @override
+  String get backupImportButton => 'Choose backup file';
+
+  @override
+  String get backupCreating => 'Creating backup...';
+
+  @override
+  String get backupCreated => 'Backup created';
+
+  @override
+  String get backupCreateFailed => 'Failed to create backup';
+
+  @override
+  String get backupEmpty => 'There is nothing to back up yet';
+
+  @override
+  String get backupRestoreConfirmTitle => 'Restore this backup?';
+
+  @override
+  String get backupRestoreConfirmMessage =>
+      'This will replace your current settings, download history, liked tracks, wishlist and playlists with the contents of the backup. This cannot be undone.';
+
+  @override
+  String get backupRestoreConfirmButton => 'Restore';
+
+  @override
+  String get backupRestoring => 'Restoring backup...';
+
+  @override
+  String get backupRestored => 'Backup restored successfully';
+
+  @override
+  String get backupRestoreFailed => 'Failed to restore backup';
+
+  @override
+  String get backupInvalidFile => 'This file is not a valid SpotiFLAC backup';
+
+  @override
+  String get backupRestoreRestartHint =>
+      'Restart the app to make sure every change is applied.';
+
+  @override
+  String get backupContentsTitle => 'Backup contents';
+
+  @override
+  String get backupContentsSettings => 'App settings';
+
+  @override
+  String backupContentsHistory(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'items',
+      one: 'item',
+    );
+    return '$count history $_temp0';
+  }
+
+  @override
+  String backupContentsLiked(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return '$count liked $_temp0';
+  }
+
+  @override
+  String backupContentsWishlist(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return '$count wishlist $_temp0';
+  }
+
+  @override
+  String backupContentsPlaylists(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count playlists',
+      one: '1 playlist',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String backupContentsArtists(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count favorite artists',
+      one: '1 favorite artist',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String backupContentsExtensions(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count extensions',
+      one: '1 extension',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String get backupIncludeSecrets => 'Include extension credentials';
+
+  @override
+  String get backupIncludeSecretsDescription =>
+      'Tokens and API keys from extensions will be saved into the backup file. Keep the file private. When off, you re-enter them after restoring.';
+
+  @override
+  String backupExtensionsRestoreFailed(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'extensions',
+      one: 'extension',
+    );
+    return '$count $_temp0 could not be reinstalled. Install them manually from the store.';
+  }
 
   @override
   String get tooltipLoveAll => 'Love All';
@@ -2901,20 +3101,20 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get downloadLocationSubtitle =>
-      'Choose storage mode for downloaded files.';
+      'Choose where to save your downloaded tracks';
 
   @override
-  String get storageModeAppFolder => 'App folder (non-SAF)';
+  String get storageModeAppFolder => 'App Folder (Recommended)';
 
   @override
-  String get storageModeAppFolderSubtitle => 'Use default Music/SpotiFLAC path';
+  String get storageModeAppFolderSubtitle =>
+      'Saves to Music/SpotiFLAC by default';
 
   @override
-  String get storageModeSaf => 'SAF folder';
+  String get storageModeSaf => 'Custom Folder (SAF)';
 
   @override
-  String get storageModeSafSubtitle =>
-      'Pick folder via Android Storage Access Framework';
+  String get storageModeSafSubtitle => 'Pick any folder, including SD card';
 
   @override
   String downloadFilenameDescription(
@@ -2926,62 +3126,73 @@ class AppLocalizationsJa extends AppLocalizations {
     Object track,
     Object year,
   ) {
-    return 'Customize how your files are named.';
+    return 'Use $artist, $title, $album, $track, $year, $date, $disc as placeholders.';
   }
 
   @override
   String get downloadFilenameInsertTag => 'Tap to insert tag:';
 
   @override
-  String get downloadSeparateSinglesEnabled => 'Albums/ and Singles/ folders';
+  String get downloadSeparateSinglesEnabled =>
+      'Singles and EPs saved in a separate folder';
 
   @override
-  String get downloadSeparateSinglesDisabled => 'All files in same structure';
+  String get downloadSeparateSinglesDisabled =>
+      'Singles and albums saved in the same folder';
 
   @override
   String get downloadArtistNameFilters => 'Artist Name Filters';
 
   @override
-  String get downloadCreatePlaylistSourceFolder =>
-      'Create playlist source folder';
+  String get downloadCreatePlaylistSourceFolder => 'Playlist Source Folder';
 
   @override
   String get downloadCreatePlaylistSourceFolderEnabled =>
-      'Playlist downloads use Playlist/ plus your normal folder structure.';
+      'A subfolder is created for each playlist';
 
   @override
   String get downloadCreatePlaylistSourceFolderDisabled =>
-      'Playlist downloads use the normal folder structure only.';
+      'All tracks saved directly to download folder';
 
   @override
   String get downloadCreatePlaylistSourceFolderRedundant =>
-      'By Playlist already places downloads inside a playlist folder.';
+      'Handled by folder organization setting';
 
   @override
   String get downloadSongLinkRegion => 'SongLink Region';
 
   @override
-  String get downloadNetworkCompatibilityMode => 'Network compatibility mode';
+  String get downloadNetworkCompatibilityMode => 'Network Compatibility Mode';
 
   @override
   String get downloadNetworkCompatibilityModeEnabled =>
-      'Enabled: try HTTP + accept invalid TLS certificates (unsafe)';
+      'Using legacy TLS settings for older networks';
 
   @override
   String get downloadNetworkCompatibilityModeDisabled =>
-      'Off: strict HTTPS certificate validation (recommended)';
+      'Using standard network settings';
+
+  @override
+  String get downloadAllowLocalNetwork => 'Allow Local Network Access';
+
+  @override
+  String get downloadAllowLocalNetworkEnabled =>
+      'Requests to local/private addresses are allowed (for local proxy or custom DNS)';
+
+  @override
+  String get downloadAllowLocalNetworkDisabled =>
+      'Local/private addresses are blocked for security';
 
   @override
   String get downloadSelectServiceToEnable =>
-      'Select a built-in service to enable';
+      'Select a provider with quality options to enable this option';
 
   @override
   String get downloadSelectTidalQobuz =>
-      'Select Tidal or Qobuz above to configure quality';
+      'Select a provider with quality options to choose audio quality';
 
   @override
-  String get downloadEmbedLyricsDisabled =>
-      'Disabled while Embed Metadata is turned off';
+  String get downloadEmbedLyricsDisabled => 'Enable metadata embedding first';
 
   @override
   String get downloadNeteaseIncludeTranslation =>
@@ -2989,11 +3200,11 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get downloadNeteaseIncludeTranslationEnabled =>
-      'Append translated lyrics when available';
+      'Chinese translation lines included';
 
   @override
   String get downloadNeteaseIncludeTranslationDisabled =>
-      'Use original lyrics only';
+      'Original lyrics only';
 
   @override
   String get downloadNeteaseIncludeRomanization =>
@@ -3001,21 +3212,21 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get downloadNeteaseIncludeRomanizationEnabled =>
-      'Append romanized lyrics when available';
+      'Romanization lines included';
 
   @override
-  String get downloadNeteaseIncludeRomanizationDisabled => 'Disabled';
+  String get downloadNeteaseIncludeRomanizationDisabled => 'No romanization';
 
   @override
-  String get downloadAppleQqMultiPerson => 'Apple/QQ Multi-Person Word-by-Word';
+  String get downloadAppleQqMultiPerson => 'Apple / QQ: Multi-Person Lyrics';
 
   @override
   String get downloadAppleQqMultiPersonEnabled =>
-      'Enable v1/v2 speaker and [bg:] tags';
+      'Speaker labels included for duets and group tracks';
 
   @override
   String get downloadAppleQqMultiPersonDisabled =>
-      'Simplified word-by-word formatting';
+      'Standard lyrics without speaker labels';
 
   @override
   String get downloadAppleElrcWordSync => 'Apple Music eLRC Word Sync';
@@ -3032,46 +3243,45 @@ class AppLocalizationsJa extends AppLocalizations {
   String get downloadMusixmatchLanguage => 'Musixmatch Language';
 
   @override
-  String get downloadMusixmatchLanguageAuto => 'Auto (original)';
+  String get downloadMusixmatchLanguageAuto => 'Auto (original language)';
 
   @override
-  String get downloadFilterContributing =>
-      'Filter contributing artists in Album Artist';
+  String get downloadFilterContributing => 'Filter Contributing Artists';
 
   @override
   String get downloadFilterContributingEnabled =>
-      'Album Artist metadata uses primary artist only';
+      'Contributing artists removed from Album Artist folder name';
 
   @override
   String get downloadFilterContributingDisabled =>
-      'Keep full Album Artist metadata value';
+      'Full Album Artist string used';
 
   @override
-  String get downloadProvidersNoneEnabled => 'None enabled';
+  String get downloadProvidersNoneEnabled => 'No providers enabled';
 
   @override
   String get downloadMusixmatchLanguageCode => 'Language code';
 
   @override
-  String get downloadMusixmatchLanguageHint => 'auto / en / es / ja';
+  String get downloadMusixmatchLanguageHint => 'e.g. en, de, ja';
 
   @override
   String get downloadMusixmatchLanguageDesc =>
-      'Set preferred language code (example: en, es, ja). Leave empty for auto.';
+      'Enter a BCP-47 language code (e.g. en, de, ja) to request translated lyrics from Musixmatch.';
 
   @override
   String get downloadMusixmatchAuto => 'Auto';
 
   @override
-  String get downloadNetworkAnySubtitle => 'WiFi + Mobile Data';
+  String get downloadNetworkAnySubtitle => 'Use WiFi or mobile data';
 
   @override
   String get downloadNetworkWifiOnlySubtitle =>
-      'Pause downloads on mobile data';
+      'Downloads pause when on mobile data';
 
   @override
   String get downloadSongLinkRegionDesc =>
-      'Used as userCountry for SongLink API lookup.';
+      'Region used when resolving track links via SongLink. Choose the country where your streaming services are available.';
 
   @override
   String get snackbarUnsupportedAudioFormat => 'Unsupported audio format';
@@ -3457,7 +3667,13 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String notifTracksDownloadedSuccess(int count) {
-    return '$count tracks downloaded successfully';
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count tracks downloaded successfully',
+      one: '1 track downloaded successfully',
+    );
+    return '$_temp0';
   }
 
   @override
@@ -4227,4 +4443,318 @@ class AppLocalizationsJa extends AppLocalizations {
   String shareSheetLinkCopied(Object service) {
     return '$service link copied';
   }
+
+  @override
+  String get libraryPlayback => 'Playback';
+
+  @override
+  String get libraryExternalPlayer => 'External player';
+
+  @override
+  String get libraryExternalPlayerSubtitle =>
+      'Recommended for listening, best quality, gapless playback, EQ, and wider format support';
+
+  @override
+  String get libraryBuiltInPreviewPlayer => 'Built-in preview player';
+
+  @override
+  String get libraryBuiltInPreviewPlayerSubtitle =>
+      'Only for quick local previews inside SpotiFLAC Mobile, not recommended for regular listening';
+
+  @override
+  String get libraryBuiltInPlayerInfo =>
+      'The built-in player is a preview tool for checking local tracks quickly. Use an external music player for actual listening.';
+
+  @override
+  String get nowPlayingTitle => 'Now Playing';
+
+  @override
+  String get nowPlayingNothingPlaying => 'Nothing is playing';
+
+  @override
+  String get nowPlayingMinimize => 'Minimize';
+
+  @override
+  String get nowPlayingUpNext => 'Up next';
+
+  @override
+  String get nowPlayingDetails => 'Details';
+
+  @override
+  String get nowPlayingOpenInExternalPlayer => 'Open in external player';
+
+  @override
+  String get nowPlayingTabPlayer => 'Player';
+
+  @override
+  String get nowPlayingTabLyrics => 'Lyrics';
+
+  @override
+  String get nowPlayingNoLyrics => 'No lyrics in this file';
+
+  @override
+  String get nowPlayingLibraryEmpty => 'Your library is empty';
+
+  @override
+  String nowPlayingShuffleLibraryFailed(String error) {
+    return 'Could not shuffle library: $error';
+  }
+
+  @override
+  String get nowPlayingShuffleOn => 'Shuffle on';
+
+  @override
+  String get nowPlayingPlayInOrder => 'Play in order';
+
+  @override
+  String get nowPlayingShuffleLibrary => 'Shuffle library';
+
+  @override
+  String get nowPlayingQueueEmpty => 'Queue is empty';
+
+  @override
+  String get nowPlayingNoMetadata => 'No metadata available';
+
+  @override
+  String get announcementUnableToOpenLink =>
+      'Unable to open link. Please try again.';
+
+  @override
+  String trackConvertLosslessOutputWithCap(String quality) {
+    return 'Lossless output with $quality cap';
+  }
+
+  @override
+  String trackConvertConfirmMessageLosslessCapped(
+    String sourceFormat,
+    String targetFormat,
+    String quality,
+  ) {
+    return 'Convert from $sourceFormat to $targetFormat ($quality)?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original file will be deleted after conversion.';
+  }
+
+  @override
+  String selectionBatchConvertConfirmMessageLosslessCapped(
+    int count,
+    String format,
+    String quality,
+  ) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return 'Convert $count $_temp0 to $format ($quality)?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original files will be deleted after conversion.';
+  }
+
+  @override
+  String trackConvertActionLabelLossless(
+    String sourceFormat,
+    String targetFormat,
+    String quality,
+  ) {
+    return '$sourceFormat → $targetFormat ($quality)';
+  }
+
+  @override
+  String trackConvertActionLabelLossy(
+    String sourceFormat,
+    String targetFormat,
+    String bitrate,
+  ) {
+    return '$sourceFormat → $targetFormat @ $bitrate';
+  }
+
+  @override
+  String get aboutPaxsenixSubtitle =>
+      'Lyrics proxy for Musixmatch, Netease, Apple Music, QQ Music, Spotify, Deezer, YouTube, Kugou, and Genius';
+
+  @override
+  String get snackbarPlayingNext => 'Playing next';
+
+  @override
+  String get snackbarAddedToQueueGeneric => 'Added to queue';
+
+  @override
+  String selectionDeletePlaylistsCount(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'playlists',
+      one: 'playlist',
+    );
+    return 'Delete $count $_temp0';
+  }
+
+  @override
+  String get actionShuffle => 'Shuffle';
+
+  @override
+  String get downloadPrimaryArtistOnlyOn => 'Primary only: On';
+
+  @override
+  String get downloadPrimaryArtistOnlyOff => 'Primary only: Off';
+
+  @override
+  String get downloadAlbumArtistMetadataPrimaryOnly =>
+      'Album Artist metadata: Primary only';
+
+  @override
+  String get downloadAlbumArtistMetadataFull => 'Album Artist metadata: Full';
+
+  @override
+  String get trackConvertOriginal => 'Original';
+
+  @override
+  String get trackConvertOriginalQuality => 'Original quality';
+
+  @override
+  String get trackConvertLosslessSuffix => 'Lossless';
+
+  @override
+  String get trackConvertDithering => 'Dithering';
+
+  @override
+  String get trackConvertResampler => 'Resampler';
+
+  @override
+  String get trackConvertDitherNone => 'None';
+
+  @override
+  String get trackConvertDitherTriangular => 'TPDF';
+
+  @override
+  String get trackConvertDitherTriangularHp => 'Triangular HP';
+
+  @override
+  String get trackConvertResamplerSwr => 'SWR';
+
+  @override
+  String get trackConvertResamplerSoxr => 'SoXr';
+
+  @override
+  String get updateSeeReleaseNotes => 'See release notes for details.';
+
+  @override
+  String get unknownTitle => 'Unknown title';
+
+  @override
+  String get trackPlayNext => 'Play next';
+
+  @override
+  String get trackAddToQueue => 'Add to queue';
+
+  @override
+  String snackbarExtensionInstalledEnable(String extensionName) {
+    return '$extensionName installed. Enable it in Settings > Extensions';
+  }
+
+  @override
+  String snackbarExtensionUpdatedVersion(String extensionName, String version) {
+    return '$extensionName updated to v$version';
+  }
+
+  @override
+  String snackbarFailedToInstallNamed(String extensionName) {
+    return 'Failed to install $extensionName';
+  }
+
+  @override
+  String snackbarFailedToUpdateNamed(String extensionName) {
+    return 'Failed to update $extensionName';
+  }
+
+  @override
+  String get releaseTypeEp => 'EP';
+
+  @override
+  String get releaseTypeSingle => 'Single';
+
+  @override
+  String get trackCoverOnline => 'Online cover';
+
+  @override
+  String get regionCountryUS => 'United States';
+
+  @override
+  String get regionCountryGB => 'United Kingdom';
+
+  @override
+  String get regionCountryFR => 'France';
+
+  @override
+  String get regionCountryDE => 'Germany';
+
+  @override
+  String get regionCountryJP => 'Japan';
+
+  @override
+  String get regionCountryKR => 'South Korea';
+
+  @override
+  String get regionCountryIN => 'India';
+
+  @override
+  String get regionCountryID => 'Indonesia';
+
+  @override
+  String get regionCountryBR => 'Brazil';
+
+  @override
+  String get regionCountryMX => 'Mexico';
+
+  @override
+  String get regionCountryAU => 'Australia';
+
+  @override
+  String get regionCountryCA => 'Canada';
+
+  @override
+  String get regionCountryXK => 'Kosovo';
+
+  @override
+  String get extensionVerificationBrowserTitle => 'Verification browser';
+
+  @override
+  String get extensionVerificationBrowserSubtitleExternal =>
+      'Open challenges in the default browser first';
+
+  @override
+  String get extensionVerificationBrowserSubtitleInApp =>
+      'Open challenges in the in-app browser first';
+
+  @override
+  String get extensionVerificationBrowserExternal => 'External';
+
+  @override
+  String get extensionVerificationBrowserInApp => 'In-app';
+
+  @override
+  String get extensionVerificationHelpTitleManual =>
+      'Open verification manually';
+
+  @override
+  String get extensionVerificationHelpTitleWaiting =>
+      'Verification still waiting';
+
+  @override
+  String get extensionVerificationHelpMessageManual =>
+      'SpotiFLAC Mobile could not open the browser automatically. Open this link in your browser, or copy it manually.';
+
+  @override
+  String get extensionVerificationHelpMessageWaiting =>
+      'If the browser did not open, or verification finished but did not return to SpotiFLAC Mobile, open this link again or copy it manually.';
+
+  @override
+  String get extensionVerificationClose => 'Close';
+
+  @override
+  String get extensionVerificationCopyLink => 'Copy link';
+
+  @override
+  String get extensionVerificationLinkCopied => 'Verification link copied';
+
+  @override
+  String get extensionVerificationOpenBrowser => 'Open browser';
 }

lib/l10n/app_localizations_ko.dart

@@ -27,7 +27,7 @@ class AppLocalizationsKo extends AppLocalizations {
   String get homeTitle => 'Home';
 
   @override
-  String get homeSubtitle => 'Paste a supported URL or search by name';
+  String get homeSubtitle => '지원되는 URL을 붙여 넣거나, 이름을 검색';
 
   @override
   String get homeEmptyTitle => 'No search providers yet';
@@ -97,10 +97,10 @@ class AppLocalizationsKo extends AppLocalizations {
   String get appearanceThemeSystem => 'System';
 
   @override
-  String get appearanceThemeLight => 'Light';
+  String get appearanceThemeLight => '밝은';
 
   @override
-  String get appearanceThemeDark => 'Dark';
+  String get appearanceThemeDark => '다크';
 
   @override
   String get appearanceDynamicColor => 'Dynamic Color';
@@ -124,7 +124,8 @@ class AppLocalizationsKo extends AppLocalizations {
   String get optionsPrimaryProvider => '기본 제공자';
 
   @override
-  String get optionsPrimaryProviderSubtitle => '음반 이름으로 검색할 때 사용되는 서비스';
+  String get optionsPrimaryProviderSubtitle =>
+      'Service used for searching by track or album name';
 
   @override
   String optionsUsingExtension(String extensionName) {
@@ -139,7 +140,8 @@ class AppLocalizationsKo extends AppLocalizations {
       'Choose which tab opens first for new search results.';
 
   @override
-  String get optionsSwitchBack => 'Deezer 또는 Spotify를 탭하여 확장 기능에서 다시 전환하세요.';
+  String get optionsSwitchBack =>
+      'Choose the default search provider to switch back from an extension';
 
   @override
   String get optionsAutoFallback => '자동 재시도';
@@ -151,16 +153,19 @@ class AppLocalizationsKo extends AppLocalizations {
   String get optionsUseExtensionProviders => '확장 기능 사용';
 
   @override
-  String get optionsUseExtensionProvidersOn => '확장 기능을 우선적으로 사용합니다';
+  String get optionsUseExtensionProvidersOn =>
+      'Extension providers are enabled';
 
   @override
-  String get optionsUseExtensionProvidersOff => '기본으로 제공되는 기능만 사용';
+  String get optionsUseExtensionProvidersOff =>
+      'Extension providers are required';
 
   @override
   String get optionsEmbedLyrics => '가사 삽입';
 
   @override
-  String get optionsEmbedLyricsSubtitle => 'FLAC 파일에 동기화된 가사를 삽입합니다';
+  String get optionsEmbedLyricsSubtitle =>
+      'Save synced lyrics alongside your downloaded tracks';
 
   @override
   String get optionsMaxQualityCover => '고품질 커버 이미지';
@@ -179,6 +184,43 @@ class AppLocalizationsKo extends AppLocalizations {
   String get optionsReplayGainSubtitleOff =>
       'Disabled: no loudness normalization tags';
 
+  @override
+  String get trackReplayGain => 'Rescan ReplayGain';
+
+  @override
+  String get trackReplayGainSubtitle =>
+      'Analyze loudness and write ReplayGain tags';
+
+  @override
+  String get trackReplayGainScanning => 'Analyzing loudness...';
+
+  @override
+  String get trackReplayGainSuccess => 'ReplayGain tags added';
+
+  @override
+  String get trackReplayGainFailed => 'Failed to add ReplayGain tags';
+
+  @override
+  String selectionReplayGainCount(int count) {
+    return 'ReplayGain ($count)';
+  }
+
+  @override
+  String get replayGainBatchConfirmTitle => 'Add ReplayGain';
+
+  @override
+  String replayGainBatchConfirmMessage(int count) {
+    return 'Analyze loudness and write ReplayGain tags to $count track(s)?';
+  }
+
+  @override
+  String get replayGainBatchAnalyzing => 'Analyzing ReplayGain...';
+
+  @override
+  String replayGainBatchSuccess(int success, int total) {
+    return 'ReplayGain added to $success of $total tracks';
+  }
+
   @override
   String get optionsArtistTagMode => 'Artist Tag Mode';
 
@@ -200,20 +242,6 @@ class AppLocalizationsKo extends AppLocalizations {
   String get optionsArtistTagModeSplitVorbisSubtitle =>
       'Write one artist tag per artist for FLAC and Opus; MP3 and M4A stay joined.';
 
-  @override
-  String get optionsConcurrentDownloads => '동시 다운로드';
-
-  @override
-  String get optionsConcurrentSequential => '순차 다운로드 (한 번에 하나)';
-
-  @override
-  String optionsConcurrentParallel(int count) {
-    return '$count개 동시 다운로드';
-  }
-
-  @override
-  String get optionsConcurrentWarning => '동시에 다수의 음반을 다운로드하면 속도 제한이 발생할 수 있습니다';
-
   @override
   String get optionsExtensionStore => 'Extension Repo';
 
@@ -374,10 +402,11 @@ class AppLocalizationsKo extends AppLocalizations {
 
   @override
   String get aboutBinimumDesc =>
-      'QQDL 및 HiFi API 개발자입니다. 이 API가 없었다면 Tidal 다운로드는 불가능했을 것입니다!';
+      'The creator of QQDL & HiFi API. This project helped shape lossless download support.';
 
   @override
-  String get aboutSachinsenalDesc => '최초의 하이파이 프로젝트 창시자. 타이달 연동의 기반을 마련한 사람!';
+  String get aboutSachinsenalDesc =>
+      'The original HiFi project creator. A foundation for lossless-source integration.';
 
   @override
   String get aboutSjdonadoDesc =>
@@ -564,6 +593,15 @@ class AppLocalizationsKo extends AppLocalizations {
   @override
   String get dialogDownload => 'Download';
 
+  @override
+  String get previewPlay => 'Play preview';
+
+  @override
+  String get previewStop => 'Stop preview';
+
+  @override
+  String get previewUnavailable => 'Preview unavailable';
+
   @override
   String get dialogDiscard => '취소';
 
@@ -829,7 +867,7 @@ class AppLocalizationsKo extends AppLocalizations {
   String get tooltipPlay => '재생';
 
   @override
-  String get filenameFormat => '';
+  String get filenameFormat => 'Filename Format';
 
   @override
   String get filenameShowAdvancedTags => '고급 태그 표시';
@@ -935,7 +973,7 @@ class AppLocalizationsKo extends AppLocalizations {
       'Only enabled extensions with download-provider capability are listed here.';
 
   @override
-  String get providerBuiltIn => 'Built-in';
+  String get providerBuiltIn => 'Legacy';
 
   @override
   String get providerExtension => 'Extension';
@@ -1101,10 +1139,10 @@ class AppLocalizationsKo extends AppLocalizations {
   String get settingsAppearanceSubtitle => 'Theme, colors, display';
 
   @override
-  String get settingsDownloadSubtitle => 'Service, quality, filename format';
+  String get settingsDownloadSubtitle => 'Service, quality, fallback';
 
   @override
-  String get settingsOptionsSubtitle => 'Fallback, lyrics, cover art, updates';
+  String get settingsOptionsSubtitle => 'Fallback, metadata, lyrics, cover art';
 
   @override
   String get settingsExtensionsSubtitle => 'Manage download providers';
@@ -1326,10 +1364,11 @@ class AppLocalizationsKo extends AppLocalizations {
   String get storeEmptyNoResults => 'No extensions found';
 
   @override
-  String get extensionDefaultProvider => 'Default (Deezer)';
+  String get extensionDefaultProvider => 'Default Search';
 
   @override
-  String get extensionDefaultProviderSubtitle => 'Use built-in search';
+  String get extensionDefaultProviderSubtitle =>
+      'Use the default metadata search';
 
   @override
   String get extensionAuthor => 'Author';
@@ -1503,7 +1542,7 @@ class AppLocalizationsKo extends AppLocalizations {
 
   @override
   String get downloadLossy320FormatDesc =>
-      'Choose the output format for Tidal 320kbps lossy downloads. The original AAC stream will be converted to your selected format.';
+      'Choose the output format for 320kbps lossy downloads. The original stream will be converted to your selected format when needed.';
 
   @override
   String get downloadLossyMp3 => 'MP3 320kbps';
@@ -1547,6 +1586,10 @@ class AppLocalizationsKo extends AppLocalizations {
   @override
   String get downloadAlbumFolderStructure => 'Album Folder Structure';
 
+  @override
+  String get albumFolderStructureDescription =>
+      'Choose how album folders are structured';
+
   @override
   String get downloadUseAlbumArtistForFolders => 'Use Album Artist for folders';
 
@@ -2073,7 +2116,7 @@ class AppLocalizationsKo extends AppLocalizations {
 
   @override
   String get tutorialWelcomeTip2 =>
-      'Get FLAC quality audio from Tidal, Qobuz, or Deezer';
+      'Get FLAC quality audio from installed download extensions';
 
   @override
   String get tutorialWelcomeTip3 =>
@@ -2403,7 +2446,7 @@ class AppLocalizationsKo extends AppLocalizations {
 
   @override
   String get trackConvertFormatSubtitle =>
-      'Convert to MP3, Opus, ALAC, or FLAC';
+      'Convert to AAC/M4A, MP3, Opus, ALAC, or FLAC';
 
   @override
   String get trackConvertTitle => 'Convert Audio';
@@ -2756,14 +2799,14 @@ class AppLocalizationsKo extends AppLocalizations {
 
   @override
   String get downloadUseAlbumArtistForFoldersAlbumSubtitle =>
-      'Artist folders use Album Artist when available';
+      'Folder named after Album Artist tag';
 
   @override
   String get downloadUseAlbumArtistForFoldersTrackSubtitle =>
-      'Artist folders use Track Artist only';
+      'Folder named after Track Artist tag';
 
   @override
-  String get lyricsProvidersTitle => 'Lyrics Providers';
+  String get lyricsProvidersTitle => 'Lyrics Provider Priority';
 
   @override
   String get lyricsProvidersDescription =>
@@ -2771,7 +2814,7 @@ class AppLocalizationsKo extends AppLocalizations {
 
   @override
   String get lyricsProvidersInfoText =>
-      'Extension lyrics providers always run before built-in providers. At least one provider must remain enabled.';
+      'Extension lyrics providers run before built-in lyrics providers. At least one provider must remain enabled.';
 
   @override
   String lyricsProvidersEnabledSection(int count) {
@@ -2813,6 +2856,10 @@ class AppLocalizationsKo extends AppLocalizations {
   String get lyricsProviderQqMusicDesc =>
       'QQ Music (good for Chinese songs, via proxy)';
 
+  @override
+  String get lyricsProviderLyricsPlusDesc =>
+      'Word-by-word karaoke lyrics (Apple/Musixmatch/Spotify/QQ, via proxy)';
+
   @override
   String get lyricsProviderExtensionDesc => 'Extension provider';
 
@@ -2831,10 +2878,168 @@ class AppLocalizationsKo extends AppLocalizations {
   String get safMigrationSuccess => 'Download folder updated to SAF mode';
 
   @override
-  String get settingsDonate => 'Donate';
+  String get settingsDonate => 'Support Development';
 
   @override
-  String get settingsDonateSubtitle => 'Support SpotiFLAC-Mobile development';
+  String get settingsDonateSubtitle => 'Buy the developer a coffee';
+
+  @override
+  String get settingsBackup => 'Backup & Restore';
+
+  @override
+  String get settingsBackupSubtitle =>
+      'Move your library, history and settings to a new device';
+
+  @override
+  String get backupTitle => 'Backup & Restore';
+
+  @override
+  String get backupExportSectionTitle => 'Create backup';
+
+  @override
+  String get backupExportSectionDescription =>
+      'Save your settings, download history, liked tracks, wishlist, favorite artists and playlists into a single file you can keep or move to another phone.';
+
+  @override
+  String get backupExportButton => 'Create backup file';
+
+  @override
+  String get backupImportSectionTitle => 'Restore backup';
+
+  @override
+  String get backupImportSectionDescription =>
+      'Pick a backup file to restore your data. This replaces the current settings, history and library on this device.';
+
+  @override
+  String get backupImportButton => 'Choose backup file';
+
+  @override
+  String get backupCreating => 'Creating backup...';
+
+  @override
+  String get backupCreated => 'Backup created';
+
+  @override
+  String get backupCreateFailed => 'Failed to create backup';
+
+  @override
+  String get backupEmpty => 'There is nothing to back up yet';
+
+  @override
+  String get backupRestoreConfirmTitle => 'Restore this backup?';
+
+  @override
+  String get backupRestoreConfirmMessage =>
+      'This will replace your current settings, download history, liked tracks, wishlist and playlists with the contents of the backup. This cannot be undone.';
+
+  @override
+  String get backupRestoreConfirmButton => 'Restore';
+
+  @override
+  String get backupRestoring => 'Restoring backup...';
+
+  @override
+  String get backupRestored => 'Backup restored successfully';
+
+  @override
+  String get backupRestoreFailed => 'Failed to restore backup';
+
+  @override
+  String get backupInvalidFile => 'This file is not a valid SpotiFLAC backup';
+
+  @override
+  String get backupRestoreRestartHint =>
+      'Restart the app to make sure every change is applied.';
+
+  @override
+  String get backupContentsTitle => 'Backup contents';
+
+  @override
+  String get backupContentsSettings => 'App settings';
+
+  @override
+  String backupContentsHistory(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'items',
+      one: 'item',
+    );
+    return '$count history $_temp0';
+  }
+
+  @override
+  String backupContentsLiked(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return '$count liked $_temp0';
+  }
+
+  @override
+  String backupContentsWishlist(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return '$count wishlist $_temp0';
+  }
+
+  @override
+  String backupContentsPlaylists(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count playlists',
+      one: '1 playlist',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String backupContentsArtists(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count favorite artists',
+      one: '1 favorite artist',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String backupContentsExtensions(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count extensions',
+      one: '1 extension',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String get backupIncludeSecrets => 'Include extension credentials';
+
+  @override
+  String get backupIncludeSecretsDescription =>
+      'Tokens and API keys from extensions will be saved into the backup file. Keep the file private. When off, you re-enter them after restoring.';
+
+  @override
+  String backupExtensionsRestoreFailed(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'extensions',
+      one: 'extension',
+    );
+    return '$count $_temp0 could not be reinstalled. Install them manually from the store.';
+  }
 
   @override
   String get tooltipLoveAll => 'Love All';
@@ -2894,20 +3099,20 @@ class AppLocalizationsKo extends AppLocalizations {
 
   @override
   String get downloadLocationSubtitle =>
-      'Choose storage mode for downloaded files.';
+      'Choose where to save your downloaded tracks';
 
   @override
-  String get storageModeAppFolder => 'App folder (non-SAF)';
+  String get storageModeAppFolder => 'App Folder (Recommended)';
 
   @override
-  String get storageModeAppFolderSubtitle => 'Use default Music/SpotiFLAC path';
+  String get storageModeAppFolderSubtitle =>
+      'Saves to Music/SpotiFLAC by default';
 
   @override
-  String get storageModeSaf => 'SAF folder';
+  String get storageModeSaf => 'Custom Folder (SAF)';
 
   @override
-  String get storageModeSafSubtitle =>
-      'Pick folder via Android Storage Access Framework';
+  String get storageModeSafSubtitle => 'Pick any folder, including SD card';
 
   @override
   String downloadFilenameDescription(
@@ -2919,62 +3124,73 @@ class AppLocalizationsKo extends AppLocalizations {
     Object track,
     Object year,
   ) {
-    return 'Customize how your files are named.';
+    return 'Use $artist, $title, $album, $track, $year, $date, $disc as placeholders.';
   }
 
   @override
   String get downloadFilenameInsertTag => 'Tap to insert tag:';
 
   @override
-  String get downloadSeparateSinglesEnabled => 'Albums/ and Singles/ folders';
+  String get downloadSeparateSinglesEnabled =>
+      'Singles and EPs saved in a separate folder';
 
   @override
-  String get downloadSeparateSinglesDisabled => 'All files in same structure';
+  String get downloadSeparateSinglesDisabled =>
+      'Singles and albums saved in the same folder';
 
   @override
   String get downloadArtistNameFilters => 'Artist Name Filters';
 
   @override
-  String get downloadCreatePlaylistSourceFolder =>
-      'Create playlist source folder';
+  String get downloadCreatePlaylistSourceFolder => 'Playlist Source Folder';
 
   @override
   String get downloadCreatePlaylistSourceFolderEnabled =>
-      'Playlist downloads use Playlist/ plus your normal folder structure.';
+      'A subfolder is created for each playlist';
 
   @override
   String get downloadCreatePlaylistSourceFolderDisabled =>
-      'Playlist downloads use the normal folder structure only.';
+      'All tracks saved directly to download folder';
 
   @override
   String get downloadCreatePlaylistSourceFolderRedundant =>
-      'By Playlist already places downloads inside a playlist folder.';
+      'Handled by folder organization setting';
 
   @override
   String get downloadSongLinkRegion => 'SongLink Region';
 
   @override
-  String get downloadNetworkCompatibilityMode => 'Network compatibility mode';
+  String get downloadNetworkCompatibilityMode => 'Network Compatibility Mode';
 
   @override
   String get downloadNetworkCompatibilityModeEnabled =>
-      'Enabled: try HTTP + accept invalid TLS certificates (unsafe)';
+      'Using legacy TLS settings for older networks';
 
   @override
   String get downloadNetworkCompatibilityModeDisabled =>
-      'Off: strict HTTPS certificate validation (recommended)';
+      'Using standard network settings';
+
+  @override
+  String get downloadAllowLocalNetwork => 'Allow Local Network Access';
+
+  @override
+  String get downloadAllowLocalNetworkEnabled =>
+      'Requests to local/private addresses are allowed (for local proxy or custom DNS)';
+
+  @override
+  String get downloadAllowLocalNetworkDisabled =>
+      'Local/private addresses are blocked for security';
 
   @override
   String get downloadSelectServiceToEnable =>
-      'Select a built-in service to enable';
+      'Select a provider with quality options to enable this option';
 
   @override
   String get downloadSelectTidalQobuz =>
-      'Select Tidal or Qobuz above to configure quality';
+      'Select a provider with quality options to choose audio quality';
 
   @override
-  String get downloadEmbedLyricsDisabled =>
-      'Disabled while Embed Metadata is turned off';
+  String get downloadEmbedLyricsDisabled => 'Enable metadata embedding first';
 
   @override
   String get downloadNeteaseIncludeTranslation =>
@@ -2982,11 +3198,11 @@ class AppLocalizationsKo extends AppLocalizations {
 
   @override
   String get downloadNeteaseIncludeTranslationEnabled =>
-      'Append translated lyrics when available';
+      'Chinese translation lines included';
 
   @override
   String get downloadNeteaseIncludeTranslationDisabled =>
-      'Use original lyrics only';
+      'Original lyrics only';
 
   @override
   String get downloadNeteaseIncludeRomanization =>
@@ -2994,21 +3210,21 @@ class AppLocalizationsKo extends AppLocalizations {
 
   @override
   String get downloadNeteaseIncludeRomanizationEnabled =>
-      'Append romanized lyrics when available';
+      'Romanization lines included';
 
   @override
-  String get downloadNeteaseIncludeRomanizationDisabled => 'Disabled';
+  String get downloadNeteaseIncludeRomanizationDisabled => 'No romanization';
 
   @override
-  String get downloadAppleQqMultiPerson => 'Apple/QQ Multi-Person Word-by-Word';
+  String get downloadAppleQqMultiPerson => 'Apple / QQ: Multi-Person Lyrics';
 
   @override
   String get downloadAppleQqMultiPersonEnabled =>
-      'Enable v1/v2 speaker and [bg:] tags';
+      'Speaker labels included for duets and group tracks';
 
   @override
   String get downloadAppleQqMultiPersonDisabled =>
-      'Simplified word-by-word formatting';
+      'Standard lyrics without speaker labels';
 
   @override
   String get downloadAppleElrcWordSync => 'Apple Music eLRC Word Sync';
@@ -3025,46 +3241,45 @@ class AppLocalizationsKo extends AppLocalizations {
   String get downloadMusixmatchLanguage => 'Musixmatch Language';
 
   @override
-  String get downloadMusixmatchLanguageAuto => 'Auto (original)';
+  String get downloadMusixmatchLanguageAuto => 'Auto (original language)';
 
   @override
-  String get downloadFilterContributing =>
-      'Filter contributing artists in Album Artist';
+  String get downloadFilterContributing => 'Filter Contributing Artists';
 
   @override
   String get downloadFilterContributingEnabled =>
-      'Album Artist metadata uses primary artist only';
+      'Contributing artists removed from Album Artist folder name';
 
   @override
   String get downloadFilterContributingDisabled =>
-      'Keep full Album Artist metadata value';
+      'Full Album Artist string used';
 
   @override
-  String get downloadProvidersNoneEnabled => 'None enabled';
+  String get downloadProvidersNoneEnabled => 'No providers enabled';
 
   @override
   String get downloadMusixmatchLanguageCode => 'Language code';
 
   @override
-  String get downloadMusixmatchLanguageHint => 'auto / en / es / ja';
+  String get downloadMusixmatchLanguageHint => 'e.g. en, de, ja';
 
   @override
   String get downloadMusixmatchLanguageDesc =>
-      'Set preferred language code (example: en, es, ja). Leave empty for auto.';
+      'Enter a BCP-47 language code (e.g. en, de, ja) to request translated lyrics from Musixmatch.';
 
   @override
   String get downloadMusixmatchAuto => 'Auto';
 
   @override
-  String get downloadNetworkAnySubtitle => 'WiFi + Mobile Data';
+  String get downloadNetworkAnySubtitle => 'Use WiFi or mobile data';
 
   @override
   String get downloadNetworkWifiOnlySubtitle =>
-      'Pause downloads on mobile data';
+      'Downloads pause when on mobile data';
 
   @override
   String get downloadSongLinkRegionDesc =>
-      'Used as userCountry for SongLink API lookup.';
+      'Region used when resolving track links via SongLink. Choose the country where your streaming services are available.';
 
   @override
   String get snackbarUnsupportedAudioFormat => 'Unsupported audio format';
@@ -3450,7 +3665,13 @@ class AppLocalizationsKo extends AppLocalizations {
 
   @override
   String notifTracksDownloadedSuccess(int count) {
-    return '$count tracks downloaded successfully';
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count tracks downloaded successfully',
+      one: '1 track downloaded successfully',
+    );
+    return '$_temp0';
   }
 
   @override
@@ -4220,4 +4441,318 @@ class AppLocalizationsKo extends AppLocalizations {
   String shareSheetLinkCopied(Object service) {
     return '$service link copied';
   }
+
+  @override
+  String get libraryPlayback => 'Playback';
+
+  @override
+  String get libraryExternalPlayer => 'External player';
+
+  @override
+  String get libraryExternalPlayerSubtitle =>
+      'Recommended for listening, best quality, gapless playback, EQ, and wider format support';
+
+  @override
+  String get libraryBuiltInPreviewPlayer => 'Built-in preview player';
+
+  @override
+  String get libraryBuiltInPreviewPlayerSubtitle =>
+      'Only for quick local previews inside SpotiFLAC Mobile, not recommended for regular listening';
+
+  @override
+  String get libraryBuiltInPlayerInfo =>
+      'The built-in player is a preview tool for checking local tracks quickly. Use an external music player for actual listening.';
+
+  @override
+  String get nowPlayingTitle => 'Now Playing';
+
+  @override
+  String get nowPlayingNothingPlaying => 'Nothing is playing';
+
+  @override
+  String get nowPlayingMinimize => 'Minimize';
+
+  @override
+  String get nowPlayingUpNext => 'Up next';
+
+  @override
+  String get nowPlayingDetails => 'Details';
+
+  @override
+  String get nowPlayingOpenInExternalPlayer => 'Open in external player';
+
+  @override
+  String get nowPlayingTabPlayer => 'Player';
+
+  @override
+  String get nowPlayingTabLyrics => 'Lyrics';
+
+  @override
+  String get nowPlayingNoLyrics => 'No lyrics in this file';
+
+  @override
+  String get nowPlayingLibraryEmpty => 'Your library is empty';
+
+  @override
+  String nowPlayingShuffleLibraryFailed(String error) {
+    return 'Could not shuffle library: $error';
+  }
+
+  @override
+  String get nowPlayingShuffleOn => 'Shuffle on';
+
+  @override
+  String get nowPlayingPlayInOrder => 'Play in order';
+
+  @override
+  String get nowPlayingShuffleLibrary => 'Shuffle library';
+
+  @override
+  String get nowPlayingQueueEmpty => 'Queue is empty';
+
+  @override
+  String get nowPlayingNoMetadata => 'No metadata available';
+
+  @override
+  String get announcementUnableToOpenLink =>
+      'Unable to open link. Please try again.';
+
+  @override
+  String trackConvertLosslessOutputWithCap(String quality) {
+    return 'Lossless output with $quality cap';
+  }
+
+  @override
+  String trackConvertConfirmMessageLosslessCapped(
+    String sourceFormat,
+    String targetFormat,
+    String quality,
+  ) {
+    return 'Convert from $sourceFormat to $targetFormat ($quality)?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original file will be deleted after conversion.';
+  }
+
+  @override
+  String selectionBatchConvertConfirmMessageLosslessCapped(
+    int count,
+    String format,
+    String quality,
+  ) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return 'Convert $count $_temp0 to $format ($quality)?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original files will be deleted after conversion.';
+  }
+
+  @override
+  String trackConvertActionLabelLossless(
+    String sourceFormat,
+    String targetFormat,
+    String quality,
+  ) {
+    return '$sourceFormat → $targetFormat ($quality)';
+  }
+
+  @override
+  String trackConvertActionLabelLossy(
+    String sourceFormat,
+    String targetFormat,
+    String bitrate,
+  ) {
+    return '$sourceFormat → $targetFormat @ $bitrate';
+  }
+
+  @override
+  String get aboutPaxsenixSubtitle =>
+      'Lyrics proxy for Musixmatch, Netease, Apple Music, QQ Music, Spotify, Deezer, YouTube, Kugou, and Genius';
+
+  @override
+  String get snackbarPlayingNext => 'Playing next';
+
+  @override
+  String get snackbarAddedToQueueGeneric => 'Added to queue';
+
+  @override
+  String selectionDeletePlaylistsCount(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'playlists',
+      one: 'playlist',
+    );
+    return 'Delete $count $_temp0';
+  }
+
+  @override
+  String get actionShuffle => 'Shuffle';
+
+  @override
+  String get downloadPrimaryArtistOnlyOn => 'Primary only: On';
+
+  @override
+  String get downloadPrimaryArtistOnlyOff => 'Primary only: Off';
+
+  @override
+  String get downloadAlbumArtistMetadataPrimaryOnly =>
+      'Album Artist metadata: Primary only';
+
+  @override
+  String get downloadAlbumArtistMetadataFull => 'Album Artist metadata: Full';
+
+  @override
+  String get trackConvertOriginal => 'Original';
+
+  @override
+  String get trackConvertOriginalQuality => 'Original quality';
+
+  @override
+  String get trackConvertLosslessSuffix => 'Lossless';
+
+  @override
+  String get trackConvertDithering => 'Dithering';
+
+  @override
+  String get trackConvertResampler => 'Resampler';
+
+  @override
+  String get trackConvertDitherNone => 'None';
+
+  @override
+  String get trackConvertDitherTriangular => 'TPDF';
+
+  @override
+  String get trackConvertDitherTriangularHp => 'Triangular HP';
+
+  @override
+  String get trackConvertResamplerSwr => 'SWR';
+
+  @override
+  String get trackConvertResamplerSoxr => 'SoXr';
+
+  @override
+  String get updateSeeReleaseNotes => 'See release notes for details.';
+
+  @override
+  String get unknownTitle => 'Unknown title';
+
+  @override
+  String get trackPlayNext => 'Play next';
+
+  @override
+  String get trackAddToQueue => 'Add to queue';
+
+  @override
+  String snackbarExtensionInstalledEnable(String extensionName) {
+    return '$extensionName installed. Enable it in Settings > Extensions';
+  }
+
+  @override
+  String snackbarExtensionUpdatedVersion(String extensionName, String version) {
+    return '$extensionName updated to v$version';
+  }
+
+  @override
+  String snackbarFailedToInstallNamed(String extensionName) {
+    return 'Failed to install $extensionName';
+  }
+
+  @override
+  String snackbarFailedToUpdateNamed(String extensionName) {
+    return 'Failed to update $extensionName';
+  }
+
+  @override
+  String get releaseTypeEp => 'EP';
+
+  @override
+  String get releaseTypeSingle => 'Single';
+
+  @override
+  String get trackCoverOnline => 'Online cover';
+
+  @override
+  String get regionCountryUS => 'United States';
+
+  @override
+  String get regionCountryGB => 'United Kingdom';
+
+  @override
+  String get regionCountryFR => 'France';
+
+  @override
+  String get regionCountryDE => 'Germany';
+
+  @override
+  String get regionCountryJP => 'Japan';
+
+  @override
+  String get regionCountryKR => 'South Korea';
+
+  @override
+  String get regionCountryIN => 'India';
+
+  @override
+  String get regionCountryID => 'Indonesia';
+
+  @override
+  String get regionCountryBR => 'Brazil';
+
+  @override
+  String get regionCountryMX => 'Mexico';
+
+  @override
+  String get regionCountryAU => 'Australia';
+
+  @override
+  String get regionCountryCA => 'Canada';
+
+  @override
+  String get regionCountryXK => 'Kosovo';
+
+  @override
+  String get extensionVerificationBrowserTitle => 'Verification browser';
+
+  @override
+  String get extensionVerificationBrowserSubtitleExternal =>
+      'Open challenges in the default browser first';
+
+  @override
+  String get extensionVerificationBrowserSubtitleInApp =>
+      'Open challenges in the in-app browser first';
+
+  @override
+  String get extensionVerificationBrowserExternal => 'External';
+
+  @override
+  String get extensionVerificationBrowserInApp => 'In-app';
+
+  @override
+  String get extensionVerificationHelpTitleManual =>
+      'Open verification manually';
+
+  @override
+  String get extensionVerificationHelpTitleWaiting =>
+      'Verification still waiting';
+
+  @override
+  String get extensionVerificationHelpMessageManual =>
+      'SpotiFLAC Mobile could not open the browser automatically. Open this link in your browser, or copy it manually.';
+
+  @override
+  String get extensionVerificationHelpMessageWaiting =>
+      'If the browser did not open, or verification finished but did not return to SpotiFLAC Mobile, open this link again or copy it manually.';
+
+  @override
+  String get extensionVerificationClose => 'Close';
+
+  @override
+  String get extensionVerificationCopyLink => 'Copy link';
+
+  @override
+  String get extensionVerificationLinkCopied => 'Verification link copied';
+
+  @override
+  String get extensionVerificationOpenBrowser => 'Open browser';
 }

lib/l10n/app_localizations_nl.dart

@@ -126,7 +126,7 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get optionsPrimaryProviderSubtitle =>
-      'Service used when searching by track name.';
+      'Service used for searching by track or album name';
 
   @override
   String optionsUsingExtension(String extensionName) {
@@ -142,7 +142,7 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get optionsSwitchBack =>
-      'Tap Deezer or Spotify to switch back from extension';
+      'Choose the default search provider to switch back from an extension';
 
   @override
   String get optionsAutoFallback => 'Auto Fallback';
@@ -155,17 +155,19 @@ class AppLocalizationsNl extends AppLocalizations {
   String get optionsUseExtensionProviders => 'Use Extension Providers';
 
   @override
-  String get optionsUseExtensionProvidersOn => 'Extensions will be tried first';
+  String get optionsUseExtensionProvidersOn =>
+      'Extension providers are enabled';
 
   @override
-  String get optionsUseExtensionProvidersOff => 'Using built-in providers only';
+  String get optionsUseExtensionProvidersOff =>
+      'Extension providers are required';
 
   @override
   String get optionsEmbedLyrics => 'Embed Lyrics';
 
   @override
   String get optionsEmbedLyricsSubtitle =>
-      'Embed synced lyrics into FLAC files';
+      'Save synced lyrics alongside your downloaded tracks';
 
   @override
   String get optionsMaxQualityCover => 'Max Quality Cover';
@@ -185,6 +187,43 @@ class AppLocalizationsNl extends AppLocalizations {
   String get optionsReplayGainSubtitleOff =>
       'Disabled: no loudness normalization tags';
 
+  @override
+  String get trackReplayGain => 'Rescan ReplayGain';
+
+  @override
+  String get trackReplayGainSubtitle =>
+      'Analyze loudness and write ReplayGain tags';
+
+  @override
+  String get trackReplayGainScanning => 'Analyzing loudness...';
+
+  @override
+  String get trackReplayGainSuccess => 'ReplayGain tags added';
+
+  @override
+  String get trackReplayGainFailed => 'Failed to add ReplayGain tags';
+
+  @override
+  String selectionReplayGainCount(int count) {
+    return 'ReplayGain ($count)';
+  }
+
+  @override
+  String get replayGainBatchConfirmTitle => 'Add ReplayGain';
+
+  @override
+  String replayGainBatchConfirmMessage(int count) {
+    return 'Analyze loudness and write ReplayGain tags to $count track(s)?';
+  }
+
+  @override
+  String get replayGainBatchAnalyzing => 'Analyzing ReplayGain...';
+
+  @override
+  String replayGainBatchSuccess(int success, int total) {
+    return 'ReplayGain added to $success of $total tracks';
+  }
+
   @override
   String get optionsArtistTagMode => 'Artist Tag Mode';
 
@@ -206,21 +245,6 @@ class AppLocalizationsNl extends AppLocalizations {
   String get optionsArtistTagModeSplitVorbisSubtitle =>
       'Write one artist tag per artist for FLAC and Opus; MP3 and M4A stay joined.';
 
-  @override
-  String get optionsConcurrentDownloads => 'Concurrent Downloads';
-
-  @override
-  String get optionsConcurrentSequential => 'Sequentiële (1 per keer)';
-
-  @override
-  String optionsConcurrentParallel(int count) {
-    return '';
-  }
-
-  @override
-  String get optionsConcurrentWarning =>
-      'Parallel downloaden kan leiden tot rate-limiting';
-
   @override
   String get optionsExtensionStore => 'Extension Repo';
 
@@ -323,7 +347,7 @@ class AppLocalizationsNl extends AppLocalizations {
   String get aboutContributors => 'Contributors';
 
   @override
-  String get aboutMobileDeveloper => '';
+  String get aboutMobileDeveloper => 'Mobile version developer';
 
   @override
   String get aboutOriginalCreator => 'Creator of the original SpotiFLAC';
@@ -385,11 +409,11 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get aboutBinimumDesc =>
-      'The creator of QQDL & HiFi API. Without this API, Tidal downloads wouldn\'t exist!';
+      'The creator of QQDL & HiFi API. This project helped shape lossless download support.';
 
   @override
   String get aboutSachinsenalDesc =>
-      'The original HiFi project creator. The foundation of Tidal integration!';
+      'The original HiFi project creator. A foundation for lossless-source integration.';
 
   @override
   String get aboutSjdonadoDesc =>
@@ -579,6 +603,15 @@ class AppLocalizationsNl extends AppLocalizations {
   @override
   String get dialogDownload => 'Download';
 
+  @override
+  String get previewPlay => 'Play preview';
+
+  @override
+  String get previewStop => 'Stop preview';
+
+  @override
+  String get previewUnavailable => 'Preview unavailable';
+
   @override
   String get dialogDiscard => 'Discard';
 
@@ -953,7 +986,7 @@ class AppLocalizationsNl extends AppLocalizations {
       'Only enabled extensions with download-provider capability are listed here.';
 
   @override
-  String get providerBuiltIn => 'Built-in';
+  String get providerBuiltIn => 'Legacy';
 
   @override
   String get providerExtension => 'Extension';
@@ -1121,10 +1154,10 @@ class AppLocalizationsNl extends AppLocalizations {
   String get settingsAppearanceSubtitle => 'Theme, colors, display';
 
   @override
-  String get settingsDownloadSubtitle => 'Service, quality, filename format';
+  String get settingsDownloadSubtitle => 'Service, quality, fallback';
 
   @override
-  String get settingsOptionsSubtitle => 'Fallback, lyrics, cover art, updates';
+  String get settingsOptionsSubtitle => 'Fallback, metadata, lyrics, cover art';
 
   @override
   String get settingsExtensionsSubtitle => 'Manage download providers';
@@ -1346,10 +1379,11 @@ class AppLocalizationsNl extends AppLocalizations {
   String get storeEmptyNoResults => 'No extensions found';
 
   @override
-  String get extensionDefaultProvider => 'Default (Deezer)';
+  String get extensionDefaultProvider => 'Default Search';
 
   @override
-  String get extensionDefaultProviderSubtitle => 'Use built-in search';
+  String get extensionDefaultProviderSubtitle =>
+      'Use the default metadata search';
 
   @override
   String get extensionAuthor => 'Author';
@@ -1523,7 +1557,7 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get downloadLossy320FormatDesc =>
-      'Choose the output format for Tidal 320kbps lossy downloads. The original AAC stream will be converted to your selected format.';
+      'Choose the output format for 320kbps lossy downloads. The original stream will be converted to your selected format when needed.';
 
   @override
   String get downloadLossyMp3 => 'MP3 320kbps';
@@ -1567,6 +1601,10 @@ class AppLocalizationsNl extends AppLocalizations {
   @override
   String get downloadAlbumFolderStructure => 'Album Folder Structure';
 
+  @override
+  String get albumFolderStructureDescription =>
+      'Choose how album folders are structured';
+
   @override
   String get downloadUseAlbumArtistForFolders => 'Use Album Artist for folders';
 
@@ -2093,7 +2131,7 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get tutorialWelcomeTip2 =>
-      'Get FLAC quality audio from Tidal, Qobuz, or Deezer';
+      'Get FLAC quality audio from installed download extensions';
 
   @override
   String get tutorialWelcomeTip3 =>
@@ -2423,7 +2461,7 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get trackConvertFormatSubtitle =>
-      'Convert to MP3, Opus, ALAC, or FLAC';
+      'Convert to AAC/M4A, MP3, Opus, ALAC, or FLAC';
 
   @override
   String get trackConvertTitle => 'Convert Audio';
@@ -2776,14 +2814,14 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get downloadUseAlbumArtistForFoldersAlbumSubtitle =>
-      'Artist folders use Album Artist when available';
+      'Folder named after Album Artist tag';
 
   @override
   String get downloadUseAlbumArtistForFoldersTrackSubtitle =>
-      'Artist folders use Track Artist only';
+      'Folder named after Track Artist tag';
 
   @override
-  String get lyricsProvidersTitle => 'Lyrics Providers';
+  String get lyricsProvidersTitle => 'Lyrics Provider Priority';
 
   @override
   String get lyricsProvidersDescription =>
@@ -2791,7 +2829,7 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get lyricsProvidersInfoText =>
-      'Extension lyrics providers always run before built-in providers. At least one provider must remain enabled.';
+      'Extension lyrics providers run before built-in lyrics providers. At least one provider must remain enabled.';
 
   @override
   String lyricsProvidersEnabledSection(int count) {
@@ -2833,6 +2871,10 @@ class AppLocalizationsNl extends AppLocalizations {
   String get lyricsProviderQqMusicDesc =>
       'QQ Music (good for Chinese songs, via proxy)';
 
+  @override
+  String get lyricsProviderLyricsPlusDesc =>
+      'Word-by-word karaoke lyrics (Apple/Musixmatch/Spotify/QQ, via proxy)';
+
   @override
   String get lyricsProviderExtensionDesc => 'Extension provider';
 
@@ -2851,10 +2893,168 @@ class AppLocalizationsNl extends AppLocalizations {
   String get safMigrationSuccess => 'Download folder updated to SAF mode';
 
   @override
-  String get settingsDonate => 'Donate';
+  String get settingsDonate => 'Support Development';
 
   @override
-  String get settingsDonateSubtitle => 'Support SpotiFLAC-Mobile development';
+  String get settingsDonateSubtitle => 'Buy the developer a coffee';
+
+  @override
+  String get settingsBackup => 'Backup & Restore';
+
+  @override
+  String get settingsBackupSubtitle =>
+      'Move your library, history and settings to a new device';
+
+  @override
+  String get backupTitle => 'Backup & Restore';
+
+  @override
+  String get backupExportSectionTitle => 'Create backup';
+
+  @override
+  String get backupExportSectionDescription =>
+      'Save your settings, download history, liked tracks, wishlist, favorite artists and playlists into a single file you can keep or move to another phone.';
+
+  @override
+  String get backupExportButton => 'Create backup file';
+
+  @override
+  String get backupImportSectionTitle => 'Restore backup';
+
+  @override
+  String get backupImportSectionDescription =>
+      'Pick a backup file to restore your data. This replaces the current settings, history and library on this device.';
+
+  @override
+  String get backupImportButton => 'Choose backup file';
+
+  @override
+  String get backupCreating => 'Creating backup...';
+
+  @override
+  String get backupCreated => 'Backup created';
+
+  @override
+  String get backupCreateFailed => 'Failed to create backup';
+
+  @override
+  String get backupEmpty => 'There is nothing to back up yet';
+
+  @override
+  String get backupRestoreConfirmTitle => 'Restore this backup?';
+
+  @override
+  String get backupRestoreConfirmMessage =>
+      'This will replace your current settings, download history, liked tracks, wishlist and playlists with the contents of the backup. This cannot be undone.';
+
+  @override
+  String get backupRestoreConfirmButton => 'Restore';
+
+  @override
+  String get backupRestoring => 'Restoring backup...';
+
+  @override
+  String get backupRestored => 'Backup restored successfully';
+
+  @override
+  String get backupRestoreFailed => 'Failed to restore backup';
+
+  @override
+  String get backupInvalidFile => 'This file is not a valid SpotiFLAC backup';
+
+  @override
+  String get backupRestoreRestartHint =>
+      'Restart the app to make sure every change is applied.';
+
+  @override
+  String get backupContentsTitle => 'Backup contents';
+
+  @override
+  String get backupContentsSettings => 'App settings';
+
+  @override
+  String backupContentsHistory(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'items',
+      one: 'item',
+    );
+    return '$count history $_temp0';
+  }
+
+  @override
+  String backupContentsLiked(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return '$count liked $_temp0';
+  }
+
+  @override
+  String backupContentsWishlist(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return '$count wishlist $_temp0';
+  }
+
+  @override
+  String backupContentsPlaylists(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count playlists',
+      one: '1 playlist',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String backupContentsArtists(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count favorite artists',
+      one: '1 favorite artist',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String backupContentsExtensions(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count extensions',
+      one: '1 extension',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String get backupIncludeSecrets => 'Include extension credentials';
+
+  @override
+  String get backupIncludeSecretsDescription =>
+      'Tokens and API keys from extensions will be saved into the backup file. Keep the file private. When off, you re-enter them after restoring.';
+
+  @override
+  String backupExtensionsRestoreFailed(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'extensions',
+      one: 'extension',
+    );
+    return '$count $_temp0 could not be reinstalled. Install them manually from the store.';
+  }
 
   @override
   String get tooltipLoveAll => 'Love All';
@@ -2914,20 +3114,20 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get downloadLocationSubtitle =>
-      'Choose storage mode for downloaded files.';
+      'Choose where to save your downloaded tracks';
 
   @override
-  String get storageModeAppFolder => 'App folder (non-SAF)';
+  String get storageModeAppFolder => 'App Folder (Recommended)';
 
   @override
-  String get storageModeAppFolderSubtitle => 'Use default Music/SpotiFLAC path';
+  String get storageModeAppFolderSubtitle =>
+      'Saves to Music/SpotiFLAC by default';
 
   @override
-  String get storageModeSaf => 'SAF folder';
+  String get storageModeSaf => 'Custom Folder (SAF)';
 
   @override
-  String get storageModeSafSubtitle =>
-      'Pick folder via Android Storage Access Framework';
+  String get storageModeSafSubtitle => 'Pick any folder, including SD card';
 
   @override
   String downloadFilenameDescription(
@@ -2939,62 +3139,73 @@ class AppLocalizationsNl extends AppLocalizations {
     Object track,
     Object year,
   ) {
-    return 'Customize how your files are named.';
+    return 'Use $artist, $title, $album, $track, $year, $date, $disc as placeholders.';
   }
 
   @override
   String get downloadFilenameInsertTag => 'Tap to insert tag:';
 
   @override
-  String get downloadSeparateSinglesEnabled => 'Albums/ and Singles/ folders';
+  String get downloadSeparateSinglesEnabled =>
+      'Singles and EPs saved in a separate folder';
 
   @override
-  String get downloadSeparateSinglesDisabled => 'All files in same structure';
+  String get downloadSeparateSinglesDisabled =>
+      'Singles and albums saved in the same folder';
 
   @override
   String get downloadArtistNameFilters => 'Artist Name Filters';
 
   @override
-  String get downloadCreatePlaylistSourceFolder =>
-      'Create playlist source folder';
+  String get downloadCreatePlaylistSourceFolder => 'Playlist Source Folder';
 
   @override
   String get downloadCreatePlaylistSourceFolderEnabled =>
-      'Playlist downloads use Playlist/ plus your normal folder structure.';
+      'A subfolder is created for each playlist';
 
   @override
   String get downloadCreatePlaylistSourceFolderDisabled =>
-      'Playlist downloads use the normal folder structure only.';
+      'All tracks saved directly to download folder';
 
   @override
   String get downloadCreatePlaylistSourceFolderRedundant =>
-      'By Playlist already places downloads inside a playlist folder.';
+      'Handled by folder organization setting';
 
   @override
   String get downloadSongLinkRegion => 'SongLink Region';
 
   @override
-  String get downloadNetworkCompatibilityMode => 'Network compatibility mode';
+  String get downloadNetworkCompatibilityMode => 'Network Compatibility Mode';
 
   @override
   String get downloadNetworkCompatibilityModeEnabled =>
-      'Enabled: try HTTP + accept invalid TLS certificates (unsafe)';
+      'Using legacy TLS settings for older networks';
 
   @override
   String get downloadNetworkCompatibilityModeDisabled =>
-      'Off: strict HTTPS certificate validation (recommended)';
+      'Using standard network settings';
+
+  @override
+  String get downloadAllowLocalNetwork => 'Allow Local Network Access';
+
+  @override
+  String get downloadAllowLocalNetworkEnabled =>
+      'Requests to local/private addresses are allowed (for local proxy or custom DNS)';
+
+  @override
+  String get downloadAllowLocalNetworkDisabled =>
+      'Local/private addresses are blocked for security';
 
   @override
   String get downloadSelectServiceToEnable =>
-      'Select a built-in service to enable';
+      'Select a provider with quality options to enable this option';
 
   @override
   String get downloadSelectTidalQobuz =>
-      'Select Tidal or Qobuz above to configure quality';
+      'Select a provider with quality options to choose audio quality';
 
   @override
-  String get downloadEmbedLyricsDisabled =>
-      'Disabled while Embed Metadata is turned off';
+  String get downloadEmbedLyricsDisabled => 'Enable metadata embedding first';
 
   @override
   String get downloadNeteaseIncludeTranslation =>
@@ -3002,11 +3213,11 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get downloadNeteaseIncludeTranslationEnabled =>
-      'Append translated lyrics when available';
+      'Chinese translation lines included';
 
   @override
   String get downloadNeteaseIncludeTranslationDisabled =>
-      'Use original lyrics only';
+      'Original lyrics only';
 
   @override
   String get downloadNeteaseIncludeRomanization =>
@@ -3014,21 +3225,21 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get downloadNeteaseIncludeRomanizationEnabled =>
-      'Append romanized lyrics when available';
+      'Romanization lines included';
 
   @override
-  String get downloadNeteaseIncludeRomanizationDisabled => 'Disabled';
+  String get downloadNeteaseIncludeRomanizationDisabled => 'No romanization';
 
   @override
-  String get downloadAppleQqMultiPerson => 'Apple/QQ Multi-Person Word-by-Word';
+  String get downloadAppleQqMultiPerson => 'Apple / QQ: Multi-Person Lyrics';
 
   @override
   String get downloadAppleQqMultiPersonEnabled =>
-      'Enable v1/v2 speaker and [bg:] tags';
+      'Speaker labels included for duets and group tracks';
 
   @override
   String get downloadAppleQqMultiPersonDisabled =>
-      'Simplified word-by-word formatting';
+      'Standard lyrics without speaker labels';
 
   @override
   String get downloadAppleElrcWordSync => 'Apple Music eLRC Word Sync';
@@ -3045,46 +3256,45 @@ class AppLocalizationsNl extends AppLocalizations {
   String get downloadMusixmatchLanguage => 'Musixmatch Language';
 
   @override
-  String get downloadMusixmatchLanguageAuto => 'Auto (original)';
+  String get downloadMusixmatchLanguageAuto => 'Auto (original language)';
 
   @override
-  String get downloadFilterContributing =>
-      'Filter contributing artists in Album Artist';
+  String get downloadFilterContributing => 'Filter Contributing Artists';
 
   @override
   String get downloadFilterContributingEnabled =>
-      'Album Artist metadata uses primary artist only';
+      'Contributing artists removed from Album Artist folder name';
 
   @override
   String get downloadFilterContributingDisabled =>
-      'Keep full Album Artist metadata value';
+      'Full Album Artist string used';
 
   @override
-  String get downloadProvidersNoneEnabled => 'None enabled';
+  String get downloadProvidersNoneEnabled => 'No providers enabled';
 
   @override
   String get downloadMusixmatchLanguageCode => 'Language code';
 
   @override
-  String get downloadMusixmatchLanguageHint => 'auto / en / es / ja';
+  String get downloadMusixmatchLanguageHint => 'e.g. en, de, ja';
 
   @override
   String get downloadMusixmatchLanguageDesc =>
-      'Set preferred language code (example: en, es, ja). Leave empty for auto.';
+      'Enter a BCP-47 language code (e.g. en, de, ja) to request translated lyrics from Musixmatch.';
 
   @override
   String get downloadMusixmatchAuto => 'Auto';
 
   @override
-  String get downloadNetworkAnySubtitle => 'WiFi + Mobile Data';
+  String get downloadNetworkAnySubtitle => 'Use WiFi or mobile data';
 
   @override
   String get downloadNetworkWifiOnlySubtitle =>
-      'Pause downloads on mobile data';
+      'Downloads pause when on mobile data';
 
   @override
   String get downloadSongLinkRegionDesc =>
-      'Used as userCountry for SongLink API lookup.';
+      'Region used when resolving track links via SongLink. Choose the country where your streaming services are available.';
 
   @override
   String get snackbarUnsupportedAudioFormat => 'Unsupported audio format';
@@ -3470,7 +3680,13 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String notifTracksDownloadedSuccess(int count) {
-    return '$count tracks downloaded successfully';
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count tracks downloaded successfully',
+      one: '1 track downloaded successfully',
+    );
+    return '$_temp0';
   }
 
   @override
@@ -4240,4 +4456,318 @@ class AppLocalizationsNl extends AppLocalizations {
   String shareSheetLinkCopied(Object service) {
     return '$service link copied';
   }
+
+  @override
+  String get libraryPlayback => 'Playback';
+
+  @override
+  String get libraryExternalPlayer => 'External player';
+
+  @override
+  String get libraryExternalPlayerSubtitle =>
+      'Recommended for listening, best quality, gapless playback, EQ, and wider format support';
+
+  @override
+  String get libraryBuiltInPreviewPlayer => 'Built-in preview player';
+
+  @override
+  String get libraryBuiltInPreviewPlayerSubtitle =>
+      'Only for quick local previews inside SpotiFLAC Mobile, not recommended for regular listening';
+
+  @override
+  String get libraryBuiltInPlayerInfo =>
+      'The built-in player is a preview tool for checking local tracks quickly. Use an external music player for actual listening.';
+
+  @override
+  String get nowPlayingTitle => 'Now Playing';
+
+  @override
+  String get nowPlayingNothingPlaying => 'Nothing is playing';
+
+  @override
+  String get nowPlayingMinimize => 'Minimize';
+
+  @override
+  String get nowPlayingUpNext => 'Up next';
+
+  @override
+  String get nowPlayingDetails => 'Details';
+
+  @override
+  String get nowPlayingOpenInExternalPlayer => 'Open in external player';
+
+  @override
+  String get nowPlayingTabPlayer => 'Player';
+
+  @override
+  String get nowPlayingTabLyrics => 'Lyrics';
+
+  @override
+  String get nowPlayingNoLyrics => 'No lyrics in this file';
+
+  @override
+  String get nowPlayingLibraryEmpty => 'Your library is empty';
+
+  @override
+  String nowPlayingShuffleLibraryFailed(String error) {
+    return 'Could not shuffle library: $error';
+  }
+
+  @override
+  String get nowPlayingShuffleOn => 'Shuffle on';
+
+  @override
+  String get nowPlayingPlayInOrder => 'Play in order';
+
+  @override
+  String get nowPlayingShuffleLibrary => 'Shuffle library';
+
+  @override
+  String get nowPlayingQueueEmpty => 'Queue is empty';
+
+  @override
+  String get nowPlayingNoMetadata => 'No metadata available';
+
+  @override
+  String get announcementUnableToOpenLink =>
+      'Unable to open link. Please try again.';
+
+  @override
+  String trackConvertLosslessOutputWithCap(String quality) {
+    return 'Lossless output with $quality cap';
+  }
+
+  @override
+  String trackConvertConfirmMessageLosslessCapped(
+    String sourceFormat,
+    String targetFormat,
+    String quality,
+  ) {
+    return 'Convert from $sourceFormat to $targetFormat ($quality)?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original file will be deleted after conversion.';
+  }
+
+  @override
+  String selectionBatchConvertConfirmMessageLosslessCapped(
+    int count,
+    String format,
+    String quality,
+  ) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return 'Convert $count $_temp0 to $format ($quality)?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original files will be deleted after conversion.';
+  }
+
+  @override
+  String trackConvertActionLabelLossless(
+    String sourceFormat,
+    String targetFormat,
+    String quality,
+  ) {
+    return '$sourceFormat → $targetFormat ($quality)';
+  }
+
+  @override
+  String trackConvertActionLabelLossy(
+    String sourceFormat,
+    String targetFormat,
+    String bitrate,
+  ) {
+    return '$sourceFormat → $targetFormat @ $bitrate';
+  }
+
+  @override
+  String get aboutPaxsenixSubtitle =>
+      'Lyrics proxy for Musixmatch, Netease, Apple Music, QQ Music, Spotify, Deezer, YouTube, Kugou, and Genius';
+
+  @override
+  String get snackbarPlayingNext => 'Playing next';
+
+  @override
+  String get snackbarAddedToQueueGeneric => 'Added to queue';
+
+  @override
+  String selectionDeletePlaylistsCount(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'playlists',
+      one: 'playlist',
+    );
+    return 'Delete $count $_temp0';
+  }
+
+  @override
+  String get actionShuffle => 'Shuffle';
+
+  @override
+  String get downloadPrimaryArtistOnlyOn => 'Primary only: On';
+
+  @override
+  String get downloadPrimaryArtistOnlyOff => 'Primary only: Off';
+
+  @override
+  String get downloadAlbumArtistMetadataPrimaryOnly =>
+      'Album Artist metadata: Primary only';
+
+  @override
+  String get downloadAlbumArtistMetadataFull => 'Album Artist metadata: Full';
+
+  @override
+  String get trackConvertOriginal => 'Original';
+
+  @override
+  String get trackConvertOriginalQuality => 'Original quality';
+
+  @override
+  String get trackConvertLosslessSuffix => 'Lossless';
+
+  @override
+  String get trackConvertDithering => 'Dithering';
+
+  @override
+  String get trackConvertResampler => 'Resampler';
+
+  @override
+  String get trackConvertDitherNone => 'None';
+
+  @override
+  String get trackConvertDitherTriangular => 'TPDF';
+
+  @override
+  String get trackConvertDitherTriangularHp => 'Triangular HP';
+
+  @override
+  String get trackConvertResamplerSwr => 'SWR';
+
+  @override
+  String get trackConvertResamplerSoxr => 'SoXr';
+
+  @override
+  String get updateSeeReleaseNotes => 'See release notes for details.';
+
+  @override
+  String get unknownTitle => 'Unknown title';
+
+  @override
+  String get trackPlayNext => 'Play next';
+
+  @override
+  String get trackAddToQueue => 'Add to queue';
+
+  @override
+  String snackbarExtensionInstalledEnable(String extensionName) {
+    return '$extensionName installed. Enable it in Settings > Extensions';
+  }
+
+  @override
+  String snackbarExtensionUpdatedVersion(String extensionName, String version) {
+    return '$extensionName updated to v$version';
+  }
+
+  @override
+  String snackbarFailedToInstallNamed(String extensionName) {
+    return 'Failed to install $extensionName';
+  }
+
+  @override
+  String snackbarFailedToUpdateNamed(String extensionName) {
+    return 'Failed to update $extensionName';
+  }
+
+  @override
+  String get releaseTypeEp => 'EP';
+
+  @override
+  String get releaseTypeSingle => 'Single';
+
+  @override
+  String get trackCoverOnline => 'Online cover';
+
+  @override
+  String get regionCountryUS => 'United States';
+
+  @override
+  String get regionCountryGB => 'United Kingdom';
+
+  @override
+  String get regionCountryFR => 'France';
+
+  @override
+  String get regionCountryDE => 'Germany';
+
+  @override
+  String get regionCountryJP => 'Japan';
+
+  @override
+  String get regionCountryKR => 'South Korea';
+
+  @override
+  String get regionCountryIN => 'India';
+
+  @override
+  String get regionCountryID => 'Indonesia';
+
+  @override
+  String get regionCountryBR => 'Brazil';
+
+  @override
+  String get regionCountryMX => 'Mexico';
+
+  @override
+  String get regionCountryAU => 'Australia';
+
+  @override
+  String get regionCountryCA => 'Canada';
+
+  @override
+  String get regionCountryXK => 'Kosovo';
+
+  @override
+  String get extensionVerificationBrowserTitle => 'Verification browser';
+
+  @override
+  String get extensionVerificationBrowserSubtitleExternal =>
+      'Open challenges in the default browser first';
+
+  @override
+  String get extensionVerificationBrowserSubtitleInApp =>
+      'Open challenges in the in-app browser first';
+
+  @override
+  String get extensionVerificationBrowserExternal => 'External';
+
+  @override
+  String get extensionVerificationBrowserInApp => 'In-app';
+
+  @override
+  String get extensionVerificationHelpTitleManual =>
+      'Open verification manually';
+
+  @override
+  String get extensionVerificationHelpTitleWaiting =>
+      'Verification still waiting';
+
+  @override
+  String get extensionVerificationHelpMessageManual =>
+      'SpotiFLAC Mobile could not open the browser automatically. Open this link in your browser, or copy it manually.';
+
+  @override
+  String get extensionVerificationHelpMessageWaiting =>
+      'If the browser did not open, or verification finished but did not return to SpotiFLAC Mobile, open this link again or copy it manually.';
+
+  @override
+  String get extensionVerificationClose => 'Close';
+
+  @override
+  String get extensionVerificationCopyLink => 'Copy link';
+
+  @override
+  String get extensionVerificationLinkCopied => 'Verification link copied';
+
+  @override
+  String get extensionVerificationOpenBrowser => 'Open browser';
 }

lib/l10n/app_localizations_uk.dart

@@ -129,7 +129,7 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String get optionsPrimaryProviderSubtitle =>
-      'Розширення будуть випробувані першими';
+      'Service used for searching by track or album name';
 
   @override
   String optionsUsingExtension(String extensionName) {
@@ -137,15 +137,15 @@ class AppLocalizationsUk extends AppLocalizations {
   }
 
   @override
-  String get optionsDefaultSearchTab => 'Default Search Tab';
+  String get optionsDefaultSearchTab => 'Вкладка пошуку за замовчуванням';
 
   @override
   String get optionsDefaultSearchTabSubtitle =>
-      'Choose which tab opens first for new search results.';
+      'Виберіть, яка вкладка відкриється першою для нових результатів пошуку.';
 
   @override
   String get optionsSwitchBack =>
-      'Натисніть Deezer або Spotify, щоб повернутися до розширення';
+      'Choose the default search provider to switch back from an extension';
 
   @override
   String get optionsAutoFallback => 'Автоматичний резервний варіант';
@@ -160,18 +160,18 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String get optionsUseExtensionProvidersOn =>
-      'Розширення будуть випробувані першими';
+      'Extension providers are enabled';
 
   @override
   String get optionsUseExtensionProvidersOff =>
-      'Використати лише вбудованих постачальників';
+      'Extension providers are required';
 
   @override
   String get optionsEmbedLyrics => 'Вбудований текст пісні';
 
   @override
   String get optionsEmbedLyricsSubtitle =>
-      'Вбудовувати синхронізовані тексти пісень у файли FLAC';
+      'Save synced lyrics alongside your downloaded tracks';
 
   @override
   String get optionsMaxQualityCover => 'Максимальна якість обкладинки';
@@ -191,6 +191,43 @@ class AppLocalizationsUk extends AppLocalizations {
   String get optionsReplayGainSubtitleOff =>
       'Вимкнено: немає тегів нормалізації гучності';
 
+  @override
+  String get trackReplayGain => 'Rescan ReplayGain';
+
+  @override
+  String get trackReplayGainSubtitle =>
+      'Analyze loudness and write ReplayGain tags';
+
+  @override
+  String get trackReplayGainScanning => 'Analyzing loudness...';
+
+  @override
+  String get trackReplayGainSuccess => 'ReplayGain tags added';
+
+  @override
+  String get trackReplayGainFailed => 'Failed to add ReplayGain tags';
+
+  @override
+  String selectionReplayGainCount(int count) {
+    return 'ReplayGain ($count)';
+  }
+
+  @override
+  String get replayGainBatchConfirmTitle => 'Add ReplayGain';
+
+  @override
+  String replayGainBatchConfirmMessage(int count) {
+    return 'Analyze loudness and write ReplayGain tags to $count track(s)?';
+  }
+
+  @override
+  String get replayGainBatchAnalyzing => 'Analyzing ReplayGain...';
+
+  @override
+  String replayGainBatchSuccess(int success, int total) {
+    return 'ReplayGain added to $success of $total tracks';
+  }
+
   @override
   String get optionsArtistTagMode => 'Режим тегу виконавця';
 
@@ -212,21 +249,6 @@ class AppLocalizationsUk extends AppLocalizations {
   String get optionsArtistTagModeSplitVorbisSubtitle =>
       'Для FLAC та Opus на кожного виконавця додати окремий тег виконавця; MP3 та M4A залишаються об’єднаними.';
 
-  @override
-  String get optionsConcurrentDownloads => 'Кількість одночасних завантажень';
-
-  @override
-  String get optionsConcurrentSequential => 'Послідовно (по одному за раз)';
-
-  @override
-  String optionsConcurrentParallel(int count) {
-    return '$count паралельних завантажень';
-  }
-
-  @override
-  String get optionsConcurrentWarning =>
-      'Паралельні завантаження можуть призвести до обмеження швидкості';
-
   @override
   String get optionsExtensionStore => 'Репозиторій розширень';
 
@@ -395,11 +417,11 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String get aboutBinimumDesc =>
-      'Творець QQDL та HiFi API. Без цього API завантажень Tidal\'а не існувало б!';
+      'The creator of QQDL & HiFi API. This project helped shape lossless download support.';
 
   @override
   String get aboutSachinsenalDesc =>
-      'Оригінальний творець HiFi-проектів. Основа інтеграції Tidal!';
+      'The original HiFi project creator. A foundation for lossless-source integration.';
 
   @override
   String get aboutSjdonadoDesc =>
@@ -590,6 +612,15 @@ class AppLocalizationsUk extends AppLocalizations {
   @override
   String get dialogDownload => 'Завантажити';
 
+  @override
+  String get previewPlay => 'Play preview';
+
+  @override
+  String get previewStop => 'Stop preview';
+
+  @override
+  String get previewUnavailable => 'Preview unavailable';
+
   @override
   String get dialogDiscard => 'Відхилити';
 
@@ -959,14 +990,14 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String get providerPriorityFallbackExtensionsDescription =>
-      'Виберіть, які встановлені розширення завантаження можна використовувати під час автоматичного відновлення до попереднього режиму. Вбудовані постачальники все одно дотримуються порядку пріоритетності, зазначеного вище.';
+      'Choose which installed download extensions can be used during automatic fallback.';
 
   @override
   String get providerPriorityFallbackExtensionsHint =>
       'Тут перелічені лише ввімкнені розширення з можливістю завантаження через постачальника послуг.';
 
   @override
-  String get providerBuiltIn => 'Вбудований';
+  String get providerBuiltIn => 'Legacy';
 
   @override
   String get providerExtension => 'Розширення';
@@ -1137,11 +1168,10 @@ class AppLocalizationsUk extends AppLocalizations {
   String get settingsAppearanceSubtitle => 'Тема, кольори, дисплей';
 
   @override
-  String get settingsDownloadSubtitle => 'Сервіс, якість, формат назви файлу';
+  String get settingsDownloadSubtitle => 'Service, quality, fallback';
 
   @override
-  String get settingsOptionsSubtitle =>
-      'Резервний варіант, тексти пісень, обкладинка, оновлення';
+  String get settingsOptionsSubtitle => 'Fallback, metadata, lyrics, cover art';
 
   @override
   String get settingsExtensionsSubtitle =>
@@ -1368,10 +1398,11 @@ class AppLocalizationsUk extends AppLocalizations {
   String get storeEmptyNoResults => 'Розширень не знайдено';
 
   @override
-  String get extensionDefaultProvider => 'За замовчуванням (Deezer)';
+  String get extensionDefaultProvider => 'Default Search';
 
   @override
-  String get extensionDefaultProviderSubtitle => 'Використати вбудований пошук';
+  String get extensionDefaultProviderSubtitle =>
+      'Use the default metadata search';
 
   @override
   String get extensionAuthor => 'Автор';
@@ -1547,7 +1578,7 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String get downloadLossy320FormatDesc =>
-      'Виберіть вихідний формат для завантажень Tidal 320 кбіт/с із втратами. Оригінальний потік AAC буде конвертовано у вибраний вами формат.';
+      'Choose the output format for 320kbps lossy downloads. The original stream will be converted to your selected format when needed.';
 
   @override
   String get downloadLossyMp3 => 'MP3 320 кбіт/с';
@@ -1593,6 +1624,10 @@ class AppLocalizationsUk extends AppLocalizations {
   @override
   String get downloadAlbumFolderStructure => 'Структура папок альбому';
 
+  @override
+  String get albumFolderStructureDescription =>
+      'Виберіть структуру папок альбомів';
+
   @override
   String get downloadUseAlbumArtistForFolders =>
       'Використовувати виконавця альбому для папок';
@@ -2129,7 +2164,7 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String get tutorialWelcomeTip2 =>
-      'Отримуйте аудіо у якості FLAC з Tidal, Qobuz або Deezer';
+      'Get FLAC quality audio from installed download extensions';
 
   @override
   String get tutorialWelcomeTip3 =>
@@ -2464,7 +2499,7 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String get trackConvertFormatSubtitle =>
-      'Конвертувати в MP3, Opus, ALAC або FLAC';
+      'Convert to AAC/M4A, MP3, Opus, ALAC, or FLAC';
 
   @override
   String get trackConvertTitle => 'Конвертувати аудіо';
@@ -2821,14 +2856,14 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String get downloadUseAlbumArtistForFoldersAlbumSubtitle =>
-      'Папки виконавців використовують \"Виконавець альбому\", коли це можливо';
+      'Folder named after Album Artist tag';
 
   @override
   String get downloadUseAlbumArtistForFoldersTrackSubtitle =>
-      'Папки виконавців використовують лише виконавця доріжки';
+      'Folder named after Track Artist tag';
 
   @override
-  String get lyricsProvidersTitle => 'Постачальники текстів пісень';
+  String get lyricsProvidersTitle => 'Lyrics Provider Priority';
 
   @override
   String get lyricsProvidersDescription =>
@@ -2836,7 +2871,7 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String get lyricsProvidersInfoText =>
-      'Постачальники розширених текстів пісень завжди запускаються перед вбудованими постачальниками. Принаймні один постачальник має залишатися ввімкненим.';
+      'Extension lyrics providers run before built-in lyrics providers. At least one provider must remain enabled.';
 
   @override
   String lyricsProvidersEnabledSection(int count) {
@@ -2880,6 +2915,10 @@ class AppLocalizationsUk extends AppLocalizations {
   String get lyricsProviderQqMusicDesc =>
       'QQ Music (добре для китайських пісень, через проксі)';
 
+  @override
+  String get lyricsProviderLyricsPlusDesc =>
+      'Word-by-word karaoke lyrics (Apple/Musixmatch/Spotify/QQ, via proxy)';
+
   @override
   String get lyricsProviderExtensionDesc => 'Постачальник розширень';
 
@@ -2898,11 +2937,168 @@ class AppLocalizationsUk extends AppLocalizations {
   String get safMigrationSuccess => 'Папку завантажень оновлено до режиму SAF';
 
   @override
-  String get settingsDonate => 'Пожертвувати кошти';
+  String get settingsDonate => 'Support Development';
 
   @override
-  String get settingsDonateSubtitle =>
-      'Підтримка розробки SpotiFLAC для мобільних пристроїв';
+  String get settingsDonateSubtitle => 'Buy the developer a coffee';
+
+  @override
+  String get settingsBackup => 'Backup & Restore';
+
+  @override
+  String get settingsBackupSubtitle =>
+      'Move your library, history and settings to a new device';
+
+  @override
+  String get backupTitle => 'Backup & Restore';
+
+  @override
+  String get backupExportSectionTitle => 'Create backup';
+
+  @override
+  String get backupExportSectionDescription =>
+      'Save your settings, download history, liked tracks, wishlist, favorite artists and playlists into a single file you can keep or move to another phone.';
+
+  @override
+  String get backupExportButton => 'Create backup file';
+
+  @override
+  String get backupImportSectionTitle => 'Restore backup';
+
+  @override
+  String get backupImportSectionDescription =>
+      'Pick a backup file to restore your data. This replaces the current settings, history and library on this device.';
+
+  @override
+  String get backupImportButton => 'Choose backup file';
+
+  @override
+  String get backupCreating => 'Creating backup...';
+
+  @override
+  String get backupCreated => 'Backup created';
+
+  @override
+  String get backupCreateFailed => 'Failed to create backup';
+
+  @override
+  String get backupEmpty => 'There is nothing to back up yet';
+
+  @override
+  String get backupRestoreConfirmTitle => 'Restore this backup?';
+
+  @override
+  String get backupRestoreConfirmMessage =>
+      'This will replace your current settings, download history, liked tracks, wishlist and playlists with the contents of the backup. This cannot be undone.';
+
+  @override
+  String get backupRestoreConfirmButton => 'Restore';
+
+  @override
+  String get backupRestoring => 'Restoring backup...';
+
+  @override
+  String get backupRestored => 'Backup restored successfully';
+
+  @override
+  String get backupRestoreFailed => 'Failed to restore backup';
+
+  @override
+  String get backupInvalidFile => 'This file is not a valid SpotiFLAC backup';
+
+  @override
+  String get backupRestoreRestartHint =>
+      'Restart the app to make sure every change is applied.';
+
+  @override
+  String get backupContentsTitle => 'Backup contents';
+
+  @override
+  String get backupContentsSettings => 'App settings';
+
+  @override
+  String backupContentsHistory(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'items',
+      one: 'item',
+    );
+    return '$count history $_temp0';
+  }
+
+  @override
+  String backupContentsLiked(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return '$count liked $_temp0';
+  }
+
+  @override
+  String backupContentsWishlist(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return '$count wishlist $_temp0';
+  }
+
+  @override
+  String backupContentsPlaylists(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count playlists',
+      one: '1 playlist',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String backupContentsArtists(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count favorite artists',
+      one: '1 favorite artist',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String backupContentsExtensions(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count extensions',
+      one: '1 extension',
+    );
+    return '$_temp0';
+  }
+
+  @override
+  String get backupIncludeSecrets => 'Include extension credentials';
+
+  @override
+  String get backupIncludeSecretsDescription =>
+      'Tokens and API keys from extensions will be saved into the backup file. Keep the file private. When off, you re-enter them after restoring.';
+
+  @override
+  String backupExtensionsRestoreFailed(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'extensions',
+      one: 'extension',
+    );
+    return '$count $_temp0 could not be reinstalled. Install them manually from the store.';
+  }
 
   @override
   String get tooltipLoveAll => 'Уподобати всіх';
@@ -2965,21 +3161,20 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String get downloadLocationSubtitle =>
-      'Виберіть режим зберігання для завантажених файлів.';
+      'Choose where to save your downloaded tracks';
 
   @override
-  String get storageModeAppFolder => 'Папка додатку (не SAF)';
+  String get storageModeAppFolder => 'App Folder (Recommended)';
 
   @override
   String get storageModeAppFolderSubtitle =>
-      'Використовувати шлях Music/SpotiFLAC за замовчуванням';
+      'Saves to Music/SpotiFLAC by default';
 
   @override
-  String get storageModeSaf => 'Папка SAF';
+  String get storageModeSaf => 'Custom Folder (SAF)';
 
   @override
-  String get storageModeSafSubtitle =>
-      'Вибрати папку через Android Storage Access Framework';
+  String get storageModeSafSubtitle => 'Pick any folder, including SD card';
 
   @override
   String downloadFilenameDescription(
@@ -2991,73 +3186,84 @@ class AppLocalizationsUk extends AppLocalizations {
     Object track,
     Object year,
   ) {
-    return 'Налаштувати спосіб іменування ваших файлів.';
+    return 'Use $artist, $title, $album, $track, $year, $date, $disc as placeholders.';
   }
 
   @override
   String get downloadFilenameInsertTag => 'Натисніть, щоб вставити тег:';
 
   @override
-  String get downloadSeparateSinglesEnabled => 'Папки «Альбоми» та «Сингли»';
+  String get downloadSeparateSinglesEnabled =>
+      'Singles and EPs saved in a separate folder';
 
   @override
-  String get downloadSeparateSinglesDisabled => 'Всі файли в одній структурі';
+  String get downloadSeparateSinglesDisabled =>
+      'Singles and albums saved in the same folder';
 
   @override
   String get downloadArtistNameFilters => 'Фільтри імені виконавця';
 
   @override
-  String get downloadCreatePlaylistSourceFolder =>
-      'Створити папку джерела списку відтворення';
+  String get downloadCreatePlaylistSourceFolder => 'Playlist Source Folder';
 
   @override
   String get downloadCreatePlaylistSourceFolderEnabled =>
-      'Завантаження списків відтворення використовує Playlist/ плюс вашу звичайну структуру папок.';
+      'A subfolder is created for each playlist';
 
   @override
   String get downloadCreatePlaylistSourceFolderDisabled =>
-      'Завантаження списків відтворення використовують лише звичайну структуру папок.';
+      'All tracks saved directly to download folder';
 
   @override
   String get downloadCreatePlaylistSourceFolderRedundant =>
-      'За допомогою списку відтворення завантаження вже розміщуються в папці зі списком відтворення.';
+      'Handled by folder organization setting';
 
   @override
   String get downloadSongLinkRegion => 'Регіон SongLink';
 
   @override
-  String get downloadNetworkCompatibilityMode => 'Режим сумісності з мережею';
+  String get downloadNetworkCompatibilityMode => 'Network Compatibility Mode';
 
   @override
   String get downloadNetworkCompatibilityModeEnabled =>
-      'Увімкнено: спробувати HTTP + прийняти недійсні сертифікати TLS (небезпечно)';
+      'Using legacy TLS settings for older networks';
 
   @override
   String get downloadNetworkCompatibilityModeDisabled =>
-      'Вимкнено: сувора перевірка сертифіката HTTPS (рекомендовано)';
+      'Using standard network settings';
+
+  @override
+  String get downloadAllowLocalNetwork => 'Allow Local Network Access';
+
+  @override
+  String get downloadAllowLocalNetworkEnabled =>
+      'Requests to local/private addresses are allowed (for local proxy or custom DNS)';
+
+  @override
+  String get downloadAllowLocalNetworkDisabled =>
+      'Local/private addresses are blocked for security';
 
   @override
   String get downloadSelectServiceToEnable =>
-      'Виберіть вбудовану службу, яку потрібно ввімкнути';
+      'Select a provider with quality options to enable this option';
 
   @override
   String get downloadSelectTidalQobuz =>
-      'Виберіть Tidal або Qobuz вище, щоб налаштувати якість';
+      'Select a provider with quality options to choose audio quality';
 
   @override
-  String get downloadEmbedLyricsDisabled =>
-      'Вимкнено, якщо вимкнено функцію «Вбудувати метадані»';
+  String get downloadEmbedLyricsDisabled => 'Enable metadata embedding first';
 
   @override
   String get downloadNeteaseIncludeTranslation => 'Netease: Включити переклад';
 
   @override
   String get downloadNeteaseIncludeTranslationEnabled =>
-      'Додати перекладені тексти пісень, коли вони доступні';
+      'Chinese translation lines included';
 
   @override
   String get downloadNeteaseIncludeTranslationDisabled =>
-      'Використовувати лише оригінальні тексти пісень';
+      'Original lyrics only';
 
   @override
   String get downloadNeteaseIncludeRomanization =>
@@ -3065,22 +3271,21 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String get downloadNeteaseIncludeRomanizationEnabled =>
-      'Додати романізовані тексти пісень, коли це можливо';
+      'Romanization lines included';
 
   @override
-  String get downloadNeteaseIncludeRomanizationDisabled => 'Вимкнути';
+  String get downloadNeteaseIncludeRomanizationDisabled => 'No romanization';
 
   @override
-  String get downloadAppleQqMultiPerson =>
-      'Apple/QQ Багатокористувацький переклад слово за словом';
+  String get downloadAppleQqMultiPerson => 'Apple / QQ: Multi-Person Lyrics';
 
   @override
   String get downloadAppleQqMultiPersonEnabled =>
-      'Увімкнути теги динаміка v1/v2 та [bg:]';
+      'Speaker labels included for duets and group tracks';
 
   @override
   String get downloadAppleQqMultiPersonDisabled =>
-      'Спрощене послівне форматування';
+      'Standard lyrics without speaker labels';
 
   @override
   String get downloadAppleElrcWordSync => 'Apple Music eLRC Word Sync';
@@ -3097,46 +3302,45 @@ class AppLocalizationsUk extends AppLocalizations {
   String get downloadMusixmatchLanguage => 'Мова Musixmatch';
 
   @override
-  String get downloadMusixmatchLanguageAuto => 'Авто (оригінал)';
+  String get downloadMusixmatchLanguageAuto => 'Auto (original language)';
 
   @override
-  String get downloadFilterContributing =>
-      'Фільтрувати виконавців-учасників у розділі «Виконавець альбому»';
+  String get downloadFilterContributing => 'Filter Contributing Artists';
 
   @override
   String get downloadFilterContributingEnabled =>
-      'Метадані виконавця альбому використовують лише основного виконавця';
+      'Contributing artists removed from Album Artist folder name';
 
   @override
   String get downloadFilterContributingDisabled =>
-      'Зберегти повне значення метаданих виконавця альбому';
+      'Full Album Artist string used';
 
   @override
-  String get downloadProvidersNoneEnabled => 'Не ввімкнено';
+  String get downloadProvidersNoneEnabled => 'No providers enabled';
 
   @override
   String get downloadMusixmatchLanguageCode => 'Код мови';
 
   @override
-  String get downloadMusixmatchLanguageHint => 'авто / en / es / ja';
+  String get downloadMusixmatchLanguageHint => 'e.g. en, de, ja';
 
   @override
   String get downloadMusixmatchLanguageDesc =>
-      'Встановити потрібний код мови (наприклад: en, es, ja). Залиште поле порожнім для автоматичного вибору.';
+      'Enter a BCP-47 language code (e.g. en, de, ja) to request translated lyrics from Musixmatch.';
 
   @override
   String get downloadMusixmatchAuto => 'Авто';
 
   @override
-  String get downloadNetworkAnySubtitle => 'Wi-Fi + мобільний інтернет';
+  String get downloadNetworkAnySubtitle => 'Use WiFi or mobile data';
 
   @override
   String get downloadNetworkWifiOnlySubtitle =>
-      'Призупинити завантаження через мобільний інтернет';
+      'Downloads pause when on mobile data';
 
   @override
   String get downloadSongLinkRegionDesc =>
-      'Використовувати як userCountry для пошуку SongLink API.';
+      'Region used when resolving track links via SongLink. Choose the country where your streaming services are available.';
 
   @override
   String get snackbarUnsupportedAudioFormat => 'Непідтримуваний аудіоформат';
@@ -3529,7 +3733,13 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String notifTracksDownloadedSuccess(int count) {
-    return '$count треки успішно завантажено';
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count tracks downloaded successfully',
+      one: '1 track downloaded successfully',
+    );
+    return '$_temp0';
   }
 
   @override
@@ -3609,7 +3819,7 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String notifDownloadingUpdate(String version) {
-    return 'Завантаження SpotiFLAC Mobile v$version';
+    return 'Downloading SpotiFLAC Mobile v$version';
   }
 
   @override
@@ -3622,7 +3832,7 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String notifUpdateReadyBody(String version) {
-    return 'SpotiFLAC Mobile v$version завантажений. Натисніть щоб установити.';
+    return 'SpotiFLAC Mobile v$version downloaded. Tap to install.';
   }
 
   @override
@@ -4299,4 +4509,318 @@ class AppLocalizationsUk extends AppLocalizations {
   String shareSheetLinkCopied(Object service) {
     return '$service link copied';
   }
+
+  @override
+  String get libraryPlayback => 'Playback';
+
+  @override
+  String get libraryExternalPlayer => 'External player';
+
+  @override
+  String get libraryExternalPlayerSubtitle =>
+      'Recommended for listening, best quality, gapless playback, EQ, and wider format support';
+
+  @override
+  String get libraryBuiltInPreviewPlayer => 'Built-in preview player';
+
+  @override
+  String get libraryBuiltInPreviewPlayerSubtitle =>
+      'Only for quick local previews inside SpotiFLAC Mobile, not recommended for regular listening';
+
+  @override
+  String get libraryBuiltInPlayerInfo =>
+      'The built-in player is a preview tool for checking local tracks quickly. Use an external music player for actual listening.';
+
+  @override
+  String get nowPlayingTitle => 'Now Playing';
+
+  @override
+  String get nowPlayingNothingPlaying => 'Nothing is playing';
+
+  @override
+  String get nowPlayingMinimize => 'Minimize';
+
+  @override
+  String get nowPlayingUpNext => 'Up next';
+
+  @override
+  String get nowPlayingDetails => 'Details';
+
+  @override
+  String get nowPlayingOpenInExternalPlayer => 'Open in external player';
+
+  @override
+  String get nowPlayingTabPlayer => 'Player';
+
+  @override
+  String get nowPlayingTabLyrics => 'Lyrics';
+
+  @override
+  String get nowPlayingNoLyrics => 'No lyrics in this file';
+
+  @override
+  String get nowPlayingLibraryEmpty => 'Your library is empty';
+
+  @override
+  String nowPlayingShuffleLibraryFailed(String error) {
+    return 'Could not shuffle library: $error';
+  }
+
+  @override
+  String get nowPlayingShuffleOn => 'Shuffle on';
+
+  @override
+  String get nowPlayingPlayInOrder => 'Play in order';
+
+  @override
+  String get nowPlayingShuffleLibrary => 'Shuffle library';
+
+  @override
+  String get nowPlayingQueueEmpty => 'Queue is empty';
+
+  @override
+  String get nowPlayingNoMetadata => 'No metadata available';
+
+  @override
+  String get announcementUnableToOpenLink =>
+      'Unable to open link. Please try again.';
+
+  @override
+  String trackConvertLosslessOutputWithCap(String quality) {
+    return 'Lossless output with $quality cap';
+  }
+
+  @override
+  String trackConvertConfirmMessageLosslessCapped(
+    String sourceFormat,
+    String targetFormat,
+    String quality,
+  ) {
+    return 'Convert from $sourceFormat to $targetFormat ($quality)?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original file will be deleted after conversion.';
+  }
+
+  @override
+  String selectionBatchConvertConfirmMessageLosslessCapped(
+    int count,
+    String format,
+    String quality,
+  ) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'tracks',
+      one: 'track',
+    );
+    return 'Convert $count $_temp0 to $format ($quality)?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original files will be deleted after conversion.';
+  }
+
+  @override
+  String trackConvertActionLabelLossless(
+    String sourceFormat,
+    String targetFormat,
+    String quality,
+  ) {
+    return '$sourceFormat → $targetFormat ($quality)';
+  }
+
+  @override
+  String trackConvertActionLabelLossy(
+    String sourceFormat,
+    String targetFormat,
+    String bitrate,
+  ) {
+    return '$sourceFormat → $targetFormat @ $bitrate';
+  }
+
+  @override
+  String get aboutPaxsenixSubtitle =>
+      'Lyrics proxy for Musixmatch, Netease, Apple Music, QQ Music, Spotify, Deezer, YouTube, Kugou, and Genius';
+
+  @override
+  String get snackbarPlayingNext => 'Playing next';
+
+  @override
+  String get snackbarAddedToQueueGeneric => 'Added to queue';
+
+  @override
+  String selectionDeletePlaylistsCount(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: 'playlists',
+      one: 'playlist',
+    );
+    return 'Delete $count $_temp0';
+  }
+
+  @override
+  String get actionShuffle => 'Shuffle';
+
+  @override
+  String get downloadPrimaryArtistOnlyOn => 'Primary only: On';
+
+  @override
+  String get downloadPrimaryArtistOnlyOff => 'Primary only: Off';
+
+  @override
+  String get downloadAlbumArtistMetadataPrimaryOnly =>
+      'Album Artist metadata: Primary only';
+
+  @override
+  String get downloadAlbumArtistMetadataFull => 'Album Artist metadata: Full';
+
+  @override
+  String get trackConvertOriginal => 'Original';
+
+  @override
+  String get trackConvertOriginalQuality => 'Original quality';
+
+  @override
+  String get trackConvertLosslessSuffix => 'Lossless';
+
+  @override
+  String get trackConvertDithering => 'Dithering';
+
+  @override
+  String get trackConvertResampler => 'Resampler';
+
+  @override
+  String get trackConvertDitherNone => 'None';
+
+  @override
+  String get trackConvertDitherTriangular => 'TPDF';
+
+  @override
+  String get trackConvertDitherTriangularHp => 'Triangular HP';
+
+  @override
+  String get trackConvertResamplerSwr => 'SWR';
+
+  @override
+  String get trackConvertResamplerSoxr => 'SoXr';
+
+  @override
+  String get updateSeeReleaseNotes => 'See release notes for details.';
+
+  @override
+  String get unknownTitle => 'Unknown title';
+
+  @override
+  String get trackPlayNext => 'Play next';
+
+  @override
+  String get trackAddToQueue => 'Add to queue';
+
+  @override
+  String snackbarExtensionInstalledEnable(String extensionName) {
+    return '$extensionName installed. Enable it in Settings > Extensions';
+  }
+
+  @override
+  String snackbarExtensionUpdatedVersion(String extensionName, String version) {
+    return '$extensionName updated to v$version';
+  }
+
+  @override
+  String snackbarFailedToInstallNamed(String extensionName) {
+    return 'Failed to install $extensionName';
+  }
+
+  @override
+  String snackbarFailedToUpdateNamed(String extensionName) {
+    return 'Failed to update $extensionName';
+  }
+
+  @override
+  String get releaseTypeEp => 'EP';
+
+  @override
+  String get releaseTypeSingle => 'Single';
+
+  @override
+  String get trackCoverOnline => 'Online cover';
+
+  @override
+  String get regionCountryUS => 'United States';
+
+  @override
+  String get regionCountryGB => 'United Kingdom';
+
+  @override
+  String get regionCountryFR => 'France';
+
+  @override
+  String get regionCountryDE => 'Germany';
+
+  @override
+  String get regionCountryJP => 'Japan';
+
+  @override
+  String get regionCountryKR => 'South Korea';
+
+  @override
+  String get regionCountryIN => 'India';
+
+  @override
+  String get regionCountryID => 'Indonesia';
+
+  @override
+  String get regionCountryBR => 'Brazil';
+
+  @override
+  String get regionCountryMX => 'Mexico';
+
+  @override
+  String get regionCountryAU => 'Australia';
+
+  @override
+  String get regionCountryCA => 'Canada';
+
+  @override
+  String get regionCountryXK => 'Kosovo';
+
+  @override
+  String get extensionVerificationBrowserTitle => 'Verification browser';
+
+  @override
+  String get extensionVerificationBrowserSubtitleExternal =>
+      'Open challenges in the default browser first';
+
+  @override
+  String get extensionVerificationBrowserSubtitleInApp =>
+      'Open challenges in the in-app browser first';
+
+  @override
+  String get extensionVerificationBrowserExternal => 'External';
+
+  @override
+  String get extensionVerificationBrowserInApp => 'In-app';
+
+  @override
+  String get extensionVerificationHelpTitleManual =>
+      'Open verification manually';
+
+  @override
+  String get extensionVerificationHelpTitleWaiting =>
+      'Verification still waiting';
+
+  @override
+  String get extensionVerificationHelpMessageManual =>
+      'SpotiFLAC Mobile could not open the browser automatically. Open this link in your browser, or copy it manually.';
+
+  @override
+  String get extensionVerificationHelpMessageWaiting =>
+      'If the browser did not open, or verification finished but did not return to SpotiFLAC Mobile, open this link again or copy it manually.';
+
+  @override
+  String get extensionVerificationClose => 'Close';
+
+  @override
+  String get extensionVerificationCopyLink => 'Copy link';
+
+  @override
+  String get extensionVerificationLinkCopied => 'Verification link copied';
+
+  @override
+  String get extensionVerificationOpenBrowser => 'Open browser';
 }

lib/l10n/arb/app_en.arb

@@ -174,9 +174,9 @@
   "@optionsDefaultSearchTabSubtitle": {
     "description": "Subtitle for the preferred default search tab setting"
   },
-  "optionsSwitchBack": "Tap Deezer or Spotify to switch back from extension",
+  "optionsSwitchBack": "Choose the default search provider to switch back from an extension",
   "@optionsSwitchBack": {
-    "description": "Hint to switch back to built-in providers"
+    "description": "Hint to switch back from extension search"
   },
   "optionsAutoFallback": "Auto Fallback",
   "@optionsAutoFallback": {
@@ -188,15 +188,15 @@
   },
   "optionsUseExtensionProviders": "Use Extension Providers",
   "@optionsUseExtensionProviders": {
-    "description": "Enable extension download providers"
+    "description": "Legacy setting label for extension download providers"
   },
-  "optionsUseExtensionProvidersOn": "Extensions will be tried first",
+  "optionsUseExtensionProvidersOn": "Extension providers are enabled",
   "@optionsUseExtensionProvidersOn": {
     "description": "Status when extension providers enabled"
   },
-  "optionsUseExtensionProvidersOff": "Using built-in providers only",
+  "optionsUseExtensionProvidersOff": "Extension providers are required",
   "@optionsUseExtensionProvidersOff": {
-    "description": "Status when extension providers disabled"
+    "description": "Legacy status when extension providers would be disabled"
   },
   "optionsEmbedLyrics": "Embed Lyrics",
   "@optionsEmbedLyrics": {
@@ -226,6 +226,64 @@
   "@optionsReplayGainSubtitleOff": {
     "description": "Subtitle when ReplayGain is disabled"
   },
+  "trackReplayGain": "Rescan ReplayGain",
+  "@trackReplayGain": {
+    "description": "Three-dot menu option to scan loudness and write ReplayGain tags"
+  },
+  "trackReplayGainSubtitle": "Analyze loudness and write ReplayGain tags",
+  "@trackReplayGainSubtitle": {
+    "description": "Subtitle for the rescan ReplayGain menu option"
+  },
+  "trackReplayGainScanning": "Analyzing loudness...",
+  "@trackReplayGainScanning": {
+    "description": "Snackbar/progress message while scanning ReplayGain for a single track"
+  },
+  "trackReplayGainSuccess": "ReplayGain tags added",
+  "@trackReplayGainSuccess": {
+    "description": "Snackbar message after ReplayGain tags written for a single track"
+  },
+  "trackReplayGainFailed": "Failed to add ReplayGain tags",
+  "@trackReplayGainFailed": {
+    "description": "Snackbar message when ReplayGain scan/write fails"
+  },
+  "selectionReplayGainCount": "ReplayGain ({count})",
+  "@selectionReplayGainCount": {
+    "description": "Batch selection action button label for ReplayGain",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
+  },
+  "replayGainBatchConfirmTitle": "Add ReplayGain",
+  "@replayGainBatchConfirmTitle": {
+    "description": "Title of the batch ReplayGain confirmation dialog"
+  },
+  "replayGainBatchConfirmMessage": "Analyze loudness and write ReplayGain tags to {count} track(s)?",
+  "@replayGainBatchConfirmMessage": {
+    "description": "Message of the batch ReplayGain confirmation dialog",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
+  },
+  "replayGainBatchAnalyzing": "Analyzing ReplayGain...",
+  "@replayGainBatchAnalyzing": {
+    "description": "Progress dialog title while batch scanning ReplayGain"
+  },
+  "replayGainBatchSuccess": "ReplayGain added to {success} of {total} tracks",
+  "@replayGainBatchSuccess": {
+    "description": "Snackbar after batch ReplayGain completes",
+    "placeholders": {
+      "success": {
+        "type": "int"
+      },
+      "total": {
+        "type": "int"
+      }
+    }
+  },
   "optionsArtistTagMode": "Artist Tag Mode",
   "@optionsArtistTagMode": {
     "description": "Setting title for how artist metadata is written into files"
@@ -250,27 +308,6 @@
   "@optionsArtistTagModeSplitVorbisSubtitle": {
     "description": "Subtitle for split Vorbis artist tag mode"
   },
-  "optionsConcurrentDownloads": "Concurrent Downloads",
-  "@optionsConcurrentDownloads": {
-    "description": "Number of parallel downloads"
-  },
-  "optionsConcurrentSequential": "Sequential (1 at a time)",
-  "@optionsConcurrentSequential": {
-    "description": "Download one at a time"
-  },
-  "optionsConcurrentParallel": "{count} parallel downloads",
-  "@optionsConcurrentParallel": {
-    "description": "Multiple parallel downloads",
-    "placeholders": {
-      "count": {
-        "type": "int"
-      }
-    }
-  },
-  "optionsConcurrentWarning": "Parallel downloads may trigger rate limiting",
-  "@optionsConcurrentWarning": {
-    "description": "Warning about rate limits"
-  },
   "optionsExtensionStore": "Extension Repo",
   "@optionsExtensionStore": {
     "description": "Show/hide store tab"
@@ -486,11 +523,11 @@
   "@aboutVersion": {
     "description": "Version info label"
   },
-  "aboutBinimumDesc": "The creator of QQDL & HiFi API. Without this API, Tidal downloads wouldn't exist!",
+  "aboutBinimumDesc": "The creator of QQDL & HiFi API. This project helped shape lossless download support.",
   "@aboutBinimumDesc": {
     "description": "Credit description for binimum"
   },
-  "aboutSachinsenalDesc": "The original HiFi project creator. The foundation of Tidal integration!",
+  "aboutSachinsenalDesc": "The original HiFi project creator. A foundation for lossless-source integration.",
   "@aboutSachinsenalDesc": {
     "description": "Credit description for sachinsenal0x64"
   },
@@ -735,6 +772,18 @@
   "@dialogDownload": {
     "description": "Confirm button in Download All dialog"
   },
+  "previewPlay": "Play preview",
+  "@previewPlay": {
+    "description": "Tooltip for the button that plays a short track preview snippet"
+  },
+  "previewStop": "Stop preview",
+  "@previewStop": {
+    "description": "Tooltip for the button that stops the playing track preview snippet"
+  },
+  "previewUnavailable": "Preview unavailable",
+  "@previewUnavailable": {
+    "description": "Snackbar shown when a track preview snippet cannot be played"
+  },
   "dialogDiscard": "Discard",
   "@dialogDiscard": {
     "description": "Dialog button - discard changes"
@@ -1235,9 +1284,9 @@
   "@providerPriorityFallbackExtensionsHint": {
     "description": "Hint below the extension fallback selection list"
   },
-  "providerBuiltIn": "Built-in",
+  "providerBuiltIn": "Legacy",
   "@providerBuiltIn": {
-    "description": "Label for built-in providers (Tidal/Qobuz)"
+    "description": "Legacy label retained for old generated localization compatibility"
   },
   "providerExtension": "Extension",
   "@providerExtension": {
@@ -1759,11 +1808,11 @@
   "@storeEmptyNoResults": {
     "description": "Message when search/filter returns no results"
   },
-  "extensionDefaultProvider": "Default (Deezer)",
+  "extensionDefaultProvider": "Default Search",
   "@extensionDefaultProvider": {
     "description": "Default search provider option"
   },
-  "extensionDefaultProviderSubtitle": "Use built-in search",
+  "extensionDefaultProviderSubtitle": "Use the default metadata search",
   "@extensionDefaultProviderSubtitle": {
     "description": "Subtitle for default provider"
   },
@@ -1992,51 +2041,51 @@
   },
   "downloadLossy320": "Lossy 320kbps",
   "@downloadLossy320": {
-    "description": "Quality option label for Tidal lossy 320kbps"
+    "description": "Quality option label for lossy 320kbps"
   },
   "downloadLossyFormat": "Lossy Format",
   "@downloadLossyFormat": {
-    "description": "Setting title to pick output format for Tidal lossy downloads"
+    "description": "Setting title to pick output format for lossy downloads"
   },
   "downloadLossy320Format": "Lossy 320kbps Format",
   "@downloadLossy320Format": {
-    "description": "Title of the Tidal lossy format picker bottom sheet"
+    "description": "Title of the lossy format picker bottom sheet"
   },
-  "downloadLossy320FormatDesc": "Choose the output format for Tidal 320kbps lossy downloads. The original AAC stream will be converted to your selected format.",
+  "downloadLossy320FormatDesc": "Choose the output format for 320kbps lossy downloads. The original stream will be converted to your selected format when needed.",
   "@downloadLossy320FormatDesc": {
-    "description": "Description in the Tidal lossy format picker"
+    "description": "Description in the lossy format picker"
   },
   "downloadLossyMp3": "MP3 320kbps",
   "@downloadLossyMp3": {
-    "description": "Tidal lossy format option - MP3 320kbps"
+    "description": "Lossy format option - MP3 320kbps"
   },
   "downloadLossyMp3Subtitle": "Best compatibility, ~10MB per track",
   "@downloadLossyMp3Subtitle": {
-    "description": "Subtitle for MP3 320kbps Tidal lossy option"
+    "description": "Subtitle for MP3 320kbps lossy option"
   },
   "downloadLossyAac": "AAC/M4A 320kbps",
   "@downloadLossyAac": {
-    "description": "Tidal lossy format option - AAC in M4A container at 320kbps"
+    "description": "Lossy format option - AAC in M4A container at 320kbps"
   },
   "downloadLossyAacSubtitle": "Best mobile compatibility, M4A container",
   "@downloadLossyAacSubtitle": {
-    "description": "Subtitle for AAC/M4A 320kbps Tidal lossy option"
+    "description": "Subtitle for AAC/M4A 320kbps lossy option"
   },
   "downloadLossyOpus256": "Opus 256kbps",
   "@downloadLossyOpus256": {
-    "description": "Tidal lossy format option - Opus 256kbps"
+    "description": "Lossy format option - Opus 256kbps"
   },
   "downloadLossyOpus256Subtitle": "Best quality Opus, ~8MB per track",
   "@downloadLossyOpus256Subtitle": {
-    "description": "Subtitle for Opus 256kbps Tidal lossy option"
+    "description": "Subtitle for Opus 256kbps lossy option"
   },
   "downloadLossyOpus128": "Opus 128kbps",
   "@downloadLossyOpus128": {
-    "description": "Tidal lossy format option - Opus 128kbps"
+    "description": "Lossy format option - Opus 128kbps"
   },
   "downloadLossyOpus128Subtitle": "Smallest size, ~4MB per track",
   "@downloadLossyOpus128Subtitle": {
-    "description": "Subtitle for Opus 128kbps Tidal lossy option"
+    "description": "Subtitle for Opus 128kbps lossy option"
   },
   "qualityNote": "Actual quality depends on track availability from the service",
   "@qualityNote": {
@@ -2058,6 +2107,10 @@
   "@downloadAlbumFolderStructure": {
     "description": "Setting - album folder organization"
   },
+  "albumFolderStructureDescription": "Choose how album folders are structured",
+  "@albumFolderStructureDescription": {
+    "description": "Album folder structure picker description"
+  },
   "downloadUseAlbumArtistForFolders": "Use Album Artist for folders",
   "@downloadUseAlbumArtistForFolders": {
     "description": "Setting - choose whether artist folders use Album Artist or Track Artist"
@@ -2519,7 +2572,7 @@
   "@libraryAbout": {
     "description": "Section header for about info"
   },
-  "libraryAboutDescription": "Scans your existing music collection to detect duplicates when downloading. Supports FLAC, M4A, MP3, Opus, and OGG formats. Metadata is read from file tags when available.",
+  "libraryAboutDescription": "Scans your existing music collection to detect duplicates when downloading. Supports FLAC, ALAC, M4A, MP3, Opus, OGG, WAV, AIFF, and APE formats. Metadata is read from file tags when available.",
   "@libraryAboutDescription": {
     "description": "Description of local library feature"
   },
@@ -2745,7 +2798,7 @@
   "@tutorialWelcomeTip1": {
     "description": "Tutorial welcome tip 1"
   },
-  "tutorialWelcomeTip2": "Get FLAC quality audio from Tidal, Qobuz, or Deezer",
+  "tutorialWelcomeTip2": "Get FLAC quality audio from installed download extensions",
   "@tutorialWelcomeTip2": {
     "description": "Tutorial welcome tip 2"
   },
@@ -3704,7 +3757,7 @@
   "@lyricsProvidersDescription": {
     "description": "Description on the lyrics provider priority page"
   },
-  "lyricsProvidersInfoText": "Extension lyrics providers always run before built-in providers. At least one provider must remain enabled.",
+  "lyricsProvidersInfoText": "Extension lyrics providers run before built-in lyrics providers. At least one provider must remain enabled.",
   "@lyricsProvidersInfoText": {
     "description": "Info tip on lyrics provider priority page"
   },
@@ -3758,6 +3811,10 @@
   "@lyricsProviderQqMusicDesc": {
     "description": "Description for QQ Music provider"
   },
+  "lyricsProviderLyricsPlusDesc": "Word-by-word karaoke lyrics (Apple/Musixmatch/Spotify/QQ, via proxy)",
+  "@lyricsProviderLyricsPlusDesc": {
+    "description": "Description for LyricsPlus provider"
+  },
   "lyricsProviderExtensionDesc": "Extension provider",
   "@lyricsProviderExtensionDesc": {
     "description": "Generic description for extension-based lyrics providers"
@@ -3786,6 +3843,169 @@
   "@settingsDonateSubtitle": {
     "description": "Subtitle for donate menu item"
   },
+  "settingsBackup": "Backup & Restore",
+  "@settingsBackup": {
+    "description": "Settings menu item - backup and restore page"
+  },
+  "settingsBackupSubtitle": "Move your library, history and settings to a new device",
+  "@settingsBackupSubtitle": {
+    "description": "Subtitle for backup and restore settings item"
+  },
+  "backupTitle": "Backup & Restore",
+  "@backupTitle": {
+    "description": "App bar title for the backup and restore page"
+  },
+  "backupExportSectionTitle": "Create backup",
+  "@backupExportSectionTitle": {
+    "description": "Section title for the export/backup card"
+  },
+  "backupExportSectionDescription": "Save your settings, download history, liked tracks, wishlist, favorite artists and playlists into a single file you can keep or move to another phone.",
+  "@backupExportSectionDescription": {
+    "description": "Description of what a backup contains"
+  },
+  "backupExportButton": "Create backup file",
+  "@backupExportButton": {
+    "description": "Button to create and share a backup file"
+  },
+  "backupImportSectionTitle": "Restore backup",
+  "@backupImportSectionTitle": {
+    "description": "Section title for the import/restore card"
+  },
+  "backupImportSectionDescription": "Pick a backup file to restore your data. This replaces the current settings, history and library on this device.",
+  "@backupImportSectionDescription": {
+    "description": "Description for the restore action"
+  },
+  "backupImportButton": "Choose backup file",
+  "@backupImportButton": {
+    "description": "Button to pick a backup file to restore"
+  },
+  "backupCreating": "Creating backup...",
+  "@backupCreating": {
+    "description": "Progress text while a backup is being created"
+  },
+  "backupCreated": "Backup created",
+  "@backupCreated": {
+    "description": "Snackbar after a backup file is created"
+  },
+  "backupCreateFailed": "Failed to create backup",
+  "@backupCreateFailed": {
+    "description": "Snackbar when backup creation fails"
+  },
+  "backupEmpty": "There is nothing to back up yet",
+  "@backupEmpty": {
+    "description": "Snackbar when there is no data to back up"
+  },
+  "backupRestoreConfirmTitle": "Restore this backup?",
+  "@backupRestoreConfirmTitle": {
+    "description": "Confirmation dialog title before restoring a backup"
+  },
+  "backupRestoreConfirmMessage": "This will replace your current settings, download history, liked tracks, wishlist and playlists with the contents of the backup. This cannot be undone.",
+  "@backupRestoreConfirmMessage": {
+    "description": "Confirmation dialog message before restoring a backup"
+  },
+  "backupRestoreConfirmButton": "Restore",
+  "@backupRestoreConfirmButton": {
+    "description": "Confirm button to proceed with restore"
+  },
+  "backupRestoring": "Restoring backup...",
+  "@backupRestoring": {
+    "description": "Progress text while restoring a backup"
+  },
+  "backupRestored": "Backup restored successfully",
+  "@backupRestored": {
+    "description": "Snackbar after a successful restore"
+  },
+  "backupRestoreFailed": "Failed to restore backup",
+  "@backupRestoreFailed": {
+    "description": "Snackbar when restore fails"
+  },
+  "backupInvalidFile": "This file is not a valid SpotiFLAC backup",
+  "@backupInvalidFile": {
+    "description": "Snackbar when the chosen file is not a valid backup"
+  },
+  "backupRestoreRestartHint": "Restart the app to make sure every change is applied.",
+  "@backupRestoreRestartHint": {
+    "description": "Hint shown after restoring that an app restart is recommended"
+  },
+  "backupContentsTitle": "Backup contents",
+  "@backupContentsTitle": {
+    "description": "Header above the list summarizing what the backup contains"
+  },
+  "backupContentsSettings": "App settings",
+  "@backupContentsSettings": {
+    "description": "Backup contents row label for settings"
+  },
+  "backupContentsHistory": "{count} history {count, plural, =1{item} other{items}}",
+  "@backupContentsHistory": {
+    "description": "Backup contents row for history count",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
+  },
+  "backupContentsLiked": "{count} liked {count, plural, =1{track} other{tracks}}",
+  "@backupContentsLiked": {
+    "description": "Backup contents row for liked tracks count",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
+  },
+  "backupContentsWishlist": "{count} wishlist {count, plural, =1{track} other{tracks}}",
+  "@backupContentsWishlist": {
+    "description": "Backup contents row for wishlist tracks count",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
+  },
+  "backupContentsPlaylists": "{count, plural, =1{1 playlist} other{{count} playlists}}",
+  "@backupContentsPlaylists": {
+    "description": "Backup contents row for playlist count",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
+  },
+  "backupContentsArtists": "{count, plural, =1{1 favorite artist} other{{count} favorite artists}}",
+  "@backupContentsArtists": {
+    "description": "Backup contents row for favorite artists count",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
+  },
+  "backupContentsExtensions": "{count, plural, =1{1 extension} other{{count} extensions}}",
+  "@backupContentsExtensions": {
+    "description": "Backup contents row for installed extensions count",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
+  },
+  "backupIncludeSecrets": "Include extension credentials",
+  "@backupIncludeSecrets": {
+    "description": "Toggle to include secret extension settings (tokens, API keys) in the backup"
+  },
+  "backupIncludeSecretsDescription": "Tokens and API keys from extensions will be saved into the backup file. Keep the file private. When off, you re-enter them after restoring.",
+  "@backupIncludeSecretsDescription": {
+    "description": "Explanation for the include-credentials toggle"
+  },
+  "backupExtensionsRestoreFailed": "{count} {count, plural, =1{extension} other{extensions}} could not be reinstalled. Install them manually from the store.",
+  "@backupExtensionsRestoreFailed": {
+    "description": "Snackbar/hint when some extensions failed to reinstall during restore",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
+  },
   "tooltipLoveAll": "Love All",
   "@tooltipLoveAll": {
     "description": "Tooltip for the Love All button on album/playlist screens"
@@ -3942,13 +4162,25 @@
   "@downloadNetworkCompatibilityModeDisabled": {
     "description": "Subtitle when network compatibility mode is off"
   },
-  "downloadSelectServiceToEnable": "Select Tidal or Qobuz to enable this option",
+  "downloadAllowLocalNetwork": "Allow Local Network Access",
+  "@downloadAllowLocalNetwork": {
+    "description": "Setting title for allowing requests to private/local network targets"
+  },
+  "downloadAllowLocalNetworkEnabled": "Requests to local/private addresses are allowed (for local proxy or custom DNS)",
+  "@downloadAllowLocalNetworkEnabled": {
+    "description": "Subtitle when allow local network access is on"
+  },
+  "downloadAllowLocalNetworkDisabled": "Local/private addresses are blocked for security",
+  "@downloadAllowLocalNetworkDisabled": {
+    "description": "Subtitle when allow local network access is off"
+  },
+  "downloadSelectServiceToEnable": "Select a provider with quality options to enable this option",
   "@downloadSelectServiceToEnable": {
     "description": "Subtitle when quality picker is disabled due to extension service"
   },
-  "downloadSelectTidalQobuz": "Select Tidal or Qobuz to choose audio quality",
+  "downloadSelectTidalQobuz": "Select a provider with quality options to choose audio quality",
   "@downloadSelectTidalQobuz": {
-    "description": "Info shown when a non-built-in service is selected"
+    "description": "Legacy info shown when a provider does not expose quality options"
   },
   "downloadEmbedLyricsDisabled": "Enable metadata embedding first",
   "@downloadEmbedLyricsDisabled": {
@@ -4358,7 +4590,7 @@
   },
   "extensionsSearchWith": "Search with {providerName}",
   "@extensionsSearchWith": {
-    "description": "Extensions page - subtitle for built-in search provider option",
+    "description": "Extensions page - subtitle for default metadata search provider option",
     "placeholders": {
       "providerName": {
         "type": "String"
@@ -5554,5 +5786,423 @@
     "placeholders": {
       "service": {}
     }
+  },
+  "libraryPlayback": "Playback",
+  "@libraryPlayback": {
+    "description": "Section header for playback settings in library settings"
+  },
+  "libraryExternalPlayer": "External player",
+  "@libraryExternalPlayer": {
+    "description": "Setting option to use an external music player"
+  },
+  "libraryExternalPlayerSubtitle": "Recommended for listening, best quality, gapless playback, EQ, and wider format support",
+  "@libraryExternalPlayerSubtitle": {
+    "description": "Subtitle for external player option"
+  },
+  "libraryBuiltInPreviewPlayer": "Built-in preview player",
+  "@libraryBuiltInPreviewPlayer": {
+    "description": "Setting option to use the built-in preview player"
+  },
+  "libraryBuiltInPreviewPlayerSubtitle": "Only for quick local previews inside SpotiFLAC Mobile, not recommended for regular listening",
+  "@libraryBuiltInPreviewPlayerSubtitle": {
+    "description": "Subtitle for built-in preview player option"
+  },
+  "libraryBuiltInPlayerInfo": "The built-in player is a preview tool for checking local tracks quickly. Use an external music player for actual listening.",
+  "@libraryBuiltInPlayerInfo": {
+    "description": "Info note explaining the built-in player is for previews only"
+  },
+  "nowPlayingTitle": "Now Playing",
+  "@nowPlayingTitle": {
+    "description": "Title for the now playing screen"
+  },
+  "nowPlayingNothingPlaying": "Nothing is playing",
+  "@nowPlayingNothingPlaying": {
+    "description": "Empty state when no track is currently playing"
+  },
+  "nowPlayingMinimize": "Minimize",
+  "@nowPlayingMinimize": {
+    "description": "Tooltip for minimizing the now playing screen"
+  },
+  "nowPlayingUpNext": "Up next",
+  "@nowPlayingUpNext": {
+    "description": "Title for the playback queue sheet"
+  },
+  "nowPlayingDetails": "Details",
+  "@nowPlayingDetails": {
+    "description": "Menu item and section title for track metadata details"
+  },
+  "nowPlayingOpenInExternalPlayer": "Open in external player",
+  "@nowPlayingOpenInExternalPlayer": {
+    "description": "Menu item to open the current track in an external player"
+  },
+  "nowPlayingTabPlayer": "Player",
+  "@nowPlayingTabPlayer": {
+    "description": "Tab label for the player view"
+  },
+  "nowPlayingTabLyrics": "Lyrics",
+  "@nowPlayingTabLyrics": {
+    "description": "Tab label for the lyrics view"
+  },
+  "nowPlayingNoLyrics": "No lyrics in this file",
+  "@nowPlayingNoLyrics": {
+    "description": "Empty state when the playing file has no embedded lyrics"
+  },
+  "nowPlayingLibraryEmpty": "Your library is empty",
+  "@nowPlayingLibraryEmpty": {
+    "description": "Snackbar when shuffle library is requested but library has no tracks"
+  },
+  "nowPlayingShuffleLibraryFailed": "Could not shuffle library: {error}",
+  "@nowPlayingShuffleLibraryFailed": {
+    "description": "Snackbar when shuffling the library fails",
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "nowPlayingShuffleOn": "Shuffle on",
+  "@nowPlayingShuffleOn": {
+    "description": "Tooltip when shuffle mode is enabled"
+  },
+  "nowPlayingPlayInOrder": "Play in order",
+  "@nowPlayingPlayInOrder": {
+    "description": "Tooltip when shuffle mode is disabled"
+  },
+  "nowPlayingShuffleLibrary": "Shuffle library",
+  "@nowPlayingShuffleLibrary": {
+    "description": "Button label to shuffle and play the entire local library"
+  },
+  "nowPlayingQueueEmpty": "Queue is empty",
+  "@nowPlayingQueueEmpty": {
+    "description": "Empty state when the playback queue has no items"
+  },
+  "nowPlayingNoMetadata": "No metadata available",
+  "@nowPlayingNoMetadata": {
+    "description": "Empty state when track metadata cannot be loaded"
+  },
+  "announcementUnableToOpenLink": "Unable to open link. Please try again.",
+  "@announcementUnableToOpenLink": {
+    "description": "Snackbar shown when an announcement CTA link cannot be opened"
+  },
+  "trackConvertLosslessOutputWithCap": "Lossless output with {quality} cap",
+  "@trackConvertLosslessOutputWithCap": {
+    "description": "Hint shown when lossless conversion will cap bit depth or sample rate",
+    "placeholders": {
+      "quality": {
+        "type": "String"
+      }
+    }
+  },
+  "trackConvertConfirmMessageLosslessCapped": "Convert from {sourceFormat} to {targetFormat} ({quality})?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original file will be deleted after conversion.",
+  "@trackConvertConfirmMessageLosslessCapped": {
+    "description": "Confirmation dialog message for capped lossless conversion of a single file",
+    "placeholders": {
+      "sourceFormat": {
+        "type": "String"
+      },
+      "targetFormat": {
+        "type": "String"
+      },
+      "quality": {
+        "type": "String"
+      }
+    }
+  },
+  "selectionBatchConvertConfirmMessageLosslessCapped": "Convert {count} {count, plural, =1{track} other{tracks}} to {format} ({quality})?\n\nThe output stays in a lossless codec, but bit depth/sample rate will be capped. Original files will be deleted after conversion.",
+  "@selectionBatchConvertConfirmMessageLosslessCapped": {
+    "description": "Confirmation dialog message for capped lossless batch conversion",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      },
+      "format": {
+        "type": "String"
+      },
+      "quality": {
+        "type": "String"
+      }
+    }
+  },
+  "trackConvertActionLabelLossless": "{sourceFormat} → {targetFormat} ({quality})",
+  "@trackConvertActionLabelLossless": {
+    "description": "Convert button label for lossless conversion with quality cap",
+    "placeholders": {
+      "sourceFormat": {
+        "type": "String"
+      },
+      "targetFormat": {
+        "type": "String"
+      },
+      "quality": {
+        "type": "String"
+      }
+    }
+  },
+  "trackConvertActionLabelLossy": "{sourceFormat} → {targetFormat} @ {bitrate}",
+  "@trackConvertActionLabelLossy": {
+    "description": "Convert button label for lossy conversion",
+    "placeholders": {
+      "sourceFormat": {
+        "type": "String"
+      },
+      "targetFormat": {
+        "type": "String"
+      },
+      "bitrate": {
+        "type": "String"
+      }
+    }
+  },
+  "aboutPaxsenixSubtitle": "Lyrics proxy for Musixmatch, Netease, Apple Music, QQ Music, Spotify, Deezer, YouTube, Kugou, and Genius",
+  "@aboutPaxsenixSubtitle": {
+    "description": "Subtitle for Paxsenix special thanks entry on the about page"
+  },
+  "snackbarPlayingNext": "Playing next",
+  "@snackbarPlayingNext": {
+    "description": "Snackbar when a track is inserted as the next queue item"
+  },
+  "snackbarAddedToQueueGeneric": "Added to queue",
+  "@snackbarAddedToQueueGeneric": {
+    "description": "Snackbar when a track is added to the playback queue without naming it"
+  },
+  "selectionDeletePlaylistsCount": "Delete {count} {count, plural, =1{playlist} other{playlists}}",
+  "@selectionDeletePlaylistsCount": {
+    "description": "Button label for deleting multiple selected playlists",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
+  },
+  "actionShuffle": "Shuffle",
+  "@actionShuffle": {
+    "description": "Tooltip for shuffle playback action"
+  },
+  "downloadPrimaryArtistOnlyOn": "Primary only: On",
+  "@downloadPrimaryArtistOnlyOn": {
+    "description": "Status label when primary-artist-only folder naming is enabled"
+  },
+  "downloadPrimaryArtistOnlyOff": "Primary only: Off",
+  "@downloadPrimaryArtistOnlyOff": {
+    "description": "Status label when primary-artist-only folder naming is disabled"
+  },
+  "downloadAlbumArtistMetadataPrimaryOnly": "Album Artist metadata: Primary only",
+  "@downloadAlbumArtistMetadataPrimaryOnly": {
+    "description": "Status label when album-artist folder filtering uses primary artist only"
+  },
+  "downloadAlbumArtistMetadataFull": "Album Artist metadata: Full",
+  "@downloadAlbumArtistMetadataFull": {
+    "description": "Status label when album-artist folder filtering uses full metadata"
+  },
+  "trackConvertOriginal": "Original",
+  "@trackConvertOriginal": {
+    "description": "Label for keeping original bit depth or sample rate during conversion"
+  },
+  "trackConvertOriginalQuality": "Original quality",
+  "@trackConvertOriginalQuality": {
+    "description": "Label when no bit depth or sample rate cap is applied during lossless conversion"
+  },
+  "trackConvertLosslessSuffix": "Lossless",
+  "@trackConvertLosslessSuffix": {
+    "description": "Suffix used in converted lossless quality labels"
+  },
+  "trackConvertDithering": "Dithering",
+  "@trackConvertDithering": {
+    "description": "Section label for lossless conversion dithering options"
+  },
+  "trackConvertResampler": "Resampler",
+  "@trackConvertResampler": {
+    "description": "Section label for lossless conversion resampler options"
+  },
+  "trackConvertDitherNone": "None",
+  "@trackConvertDitherNone": {
+    "description": "Lossless conversion dither option with no dithering applied"
+  },
+  "trackConvertDitherTriangular": "TPDF",
+  "@trackConvertDitherTriangular": {
+    "description": "Lossless conversion triangular probability density function dither option"
+  },
+  "trackConvertDitherTriangularHp": "Triangular HP",
+  "@trackConvertDitherTriangularHp": {
+    "description": "Lossless conversion high-pass triangular dither option"
+  },
+  "trackConvertResamplerSwr": "SWR",
+  "@trackConvertResamplerSwr": {
+    "description": "Lossless conversion default FFmpeg swresample resampler option"
+  },
+  "trackConvertResamplerSoxr": "SoXr",
+  "@trackConvertResamplerSoxr": {
+    "description": "Lossless conversion SoX resampler option"
+  },
+  "updateSeeReleaseNotes": "See release notes for details.",
+  "@updateSeeReleaseNotes": {
+    "description": "Fallback changelog text when release notes cannot be parsed"
+  },
+  "unknownTitle": "Unknown title",
+  "@unknownTitle": {
+    "description": "Fallback track title when metadata is missing"
+  },
+  "trackPlayNext": "Play next",
+  "@trackPlayNext": {
+    "description": "Menu action to play a track as the next queue item"
+  },
+  "trackAddToQueue": "Add to queue",
+  "@trackAddToQueue": {
+    "description": "Menu action to add a track to the playback queue"
+  },
+  "snackbarExtensionInstalledEnable": "{extensionName} installed. Enable it in Settings > Extensions",
+  "@snackbarExtensionInstalledEnable": {
+    "description": "Snackbar after installing an extension from the repo tab",
+    "placeholders": {
+      "extensionName": {
+        "type": "String"
+      }
+    }
+  },
+  "snackbarExtensionUpdatedVersion": "{extensionName} updated to v{version}",
+  "@snackbarExtensionUpdatedVersion": {
+    "description": "Snackbar after updating an extension from the repo tab",
+    "placeholders": {
+      "extensionName": {
+        "type": "String"
+      },
+      "version": {
+        "type": "String"
+      }
+    }
+  },
+  "snackbarFailedToInstallNamed": "Failed to install {extensionName}",
+  "@snackbarFailedToInstallNamed": {
+    "description": "Snackbar when extension install fails in the repo tab",
+    "placeholders": {
+      "extensionName": {
+        "type": "String"
+      }
+    }
+  },
+  "snackbarFailedToUpdateNamed": "Failed to update {extensionName}",
+  "@snackbarFailedToUpdateNamed": {
+    "description": "Snackbar when extension update fails in the repo tab",
+    "placeholders": {
+      "extensionName": {
+        "type": "String"
+      }
+    }
+  },
+  "releaseTypeEp": "EP",
+  "@releaseTypeEp": {
+    "description": "Badge label for EP releases"
+  },
+  "releaseTypeSingle": "Single",
+  "@releaseTypeSingle": {
+    "description": "Badge label for single releases"
+  },
+  "trackCoverOnline": "Online cover",
+  "@trackCoverOnline": {
+    "description": "Label shown when metadata autofill downloaded cover art from the internet"
+  },
+  "regionCountryUS": "United States",
+  "@regionCountryUS": {
+    "description": "Country name for SongLink region picker"
+  },
+  "regionCountryGB": "United Kingdom",
+  "@regionCountryGB": {
+    "description": "Country name for SongLink region picker"
+  },
+  "regionCountryFR": "France",
+  "@regionCountryFR": {
+    "description": "Country name for SongLink region picker"
+  },
+  "regionCountryDE": "Germany",
+  "@regionCountryDE": {
+    "description": "Country name for SongLink region picker"
+  },
+  "regionCountryJP": "Japan",
+  "@regionCountryJP": {
+    "description": "Country name for SongLink region picker"
+  },
+  "regionCountryKR": "South Korea",
+  "@regionCountryKR": {
+    "description": "Country name for SongLink region picker"
+  },
+  "regionCountryIN": "India",
+  "@regionCountryIN": {
+    "description": "Country name for SongLink region picker"
+  },
+  "regionCountryID": "Indonesia",
+  "@regionCountryID": {
+    "description": "Country name for SongLink region picker"
+  },
+  "regionCountryBR": "Brazil",
+  "@regionCountryBR": {
+    "description": "Country name for SongLink region picker"
+  },
+  "regionCountryMX": "Mexico",
+  "@regionCountryMX": {
+    "description": "Country name for SongLink region picker"
+  },
+  "regionCountryAU": "Australia",
+  "@regionCountryAU": {
+    "description": "Country name for SongLink region picker"
+  },
+  "regionCountryCA": "Canada",
+  "@regionCountryCA": {
+    "description": "Country name for SongLink region picker"
+  },
+  "regionCountryXK": "Kosovo",
+  "@regionCountryXK": {
+    "description": "Country name for SongLink region picker"
+  },
+  "extensionVerificationBrowserTitle": "Verification browser",
+  "@extensionVerificationBrowserTitle": {
+    "description": "Settings option title for extension verification browser preference"
+  },
+  "extensionVerificationBrowserSubtitleExternal": "Open challenges in the default browser first",
+  "@extensionVerificationBrowserSubtitleExternal": {
+    "description": "Subtitle when external browser is preferred for extension verification"
+  },
+  "extensionVerificationBrowserSubtitleInApp": "Open challenges in the in-app browser first",
+  "@extensionVerificationBrowserSubtitleInApp": {
+    "description": "Subtitle when in-app browser is preferred for extension verification"
+  },
+  "extensionVerificationBrowserExternal": "External",
+  "@extensionVerificationBrowserExternal": {
+    "description": "Chip label for external browser verification mode"
+  },
+  "extensionVerificationBrowserInApp": "In-app",
+  "@extensionVerificationBrowserInApp": {
+    "description": "Chip label for in-app browser verification mode"
+  },
+  "extensionVerificationHelpTitleManual": "Open verification manually",
+  "@extensionVerificationHelpTitleManual": {
+    "description": "Dialog title when automatic browser launch for verification fails"
+  },
+  "extensionVerificationHelpTitleWaiting": "Verification still waiting",
+  "@extensionVerificationHelpTitleWaiting": {
+    "description": "Dialog title when verification is taking longer than expected"
+  },
+  "extensionVerificationHelpMessageManual": "SpotiFLAC Mobile could not open the browser automatically. Open this link in your browser, or copy it manually.",
+  "@extensionVerificationHelpMessageManual": {
+    "description": "Dialog message when automatic browser launch for verification fails"
+  },
+  "extensionVerificationHelpMessageWaiting": "If the browser did not open, or verification finished but did not return to SpotiFLAC Mobile, open this link again or copy it manually.",
+  "@extensionVerificationHelpMessageWaiting": {
+    "description": "Dialog message when verification may need manual browser help"
+  },
+  "extensionVerificationClose": "Close",
+  "@extensionVerificationClose": {
+    "description": "Button to dismiss the extension verification help dialog"
+  },
+  "extensionVerificationCopyLink": "Copy link",
+  "@extensionVerificationCopyLink": {
+    "description": "Button to copy the extension verification URL"
+  },
+  "extensionVerificationLinkCopied": "Verification link copied",
+  "@extensionVerificationLinkCopied": {
+    "description": "Snackbar after copying the extension verification URL"
+  },
+  "extensionVerificationOpenBrowser": "Open browser",
+  "@extensionVerificationOpenBrowser": {
+    "description": "Button to open the extension verification URL in a browser"
   }
 }

lib/l10n/arb/app_es.arb

@@ -142,9 +142,9 @@
       }
     }
   },
-  "optionsSwitchBack": "Tap Deezer or Spotify to switch back from extension",
+  "optionsSwitchBack": "Choose the default search provider to switch back from an extension",
   "@optionsSwitchBack": {
-    "description": "Hint to switch back to built-in providers"
+    "description": "Hint to switch back from extension search"
   },
   "optionsAutoFallback": "Auto Fallback",
   "@optionsAutoFallback": {
@@ -156,15 +156,15 @@
   },
   "optionsUseExtensionProviders": "Use Extension Providers",
   "@optionsUseExtensionProviders": {
-    "description": "Enable extension download providers"
+    "description": "Legacy setting label for extension download providers"
   },
-  "optionsUseExtensionProvidersOn": "Extensions will be tried first",
+  "optionsUseExtensionProvidersOn": "Extension providers are enabled",
   "@optionsUseExtensionProvidersOn": {
     "description": "Status when extension providers enabled"
   },
-  "optionsUseExtensionProvidersOff": "Using built-in providers only",
+  "optionsUseExtensionProvidersOff": "Extension providers are required",
   "@optionsUseExtensionProvidersOff": {
-    "description": "Status when extension providers disabled"
+    "description": "Legacy status when extension providers would be disabled"
   },
   "optionsEmbedLyrics": "Embed Lyrics",
   "@optionsEmbedLyrics": {
@@ -182,27 +182,6 @@
   "@optionsMaxQualityCoverSubtitle": {
     "description": "Subtitle for max quality cover"
   },
-  "optionsConcurrentDownloads": "Concurrent Downloads",
-  "@optionsConcurrentDownloads": {
-    "description": "Number of parallel downloads"
-  },
-  "optionsConcurrentSequential": "Sequential (1 at a time)",
-  "@optionsConcurrentSequential": {
-    "description": "Download one at a time"
-  },
-  "optionsConcurrentParallel": "{count} parallel downloads",
-  "@optionsConcurrentParallel": {
-    "description": "Multiple parallel downloads",
-    "placeholders": {
-      "count": {
-        "type": "int"
-      }
-    }
-  },
-  "optionsConcurrentWarning": "Parallel downloads may trigger rate limiting",
-  "@optionsConcurrentWarning": {
-    "description": "Warning about rate limits"
-  },
   "optionsExtensionStore": "Extension Store",
   "@optionsExtensionStore": {
     "description": "Show/hide store tab"
@@ -390,11 +369,11 @@
   "@aboutVersion": {
     "description": "Version info label"
   },
-  "aboutBinimumDesc": "The creator of QQDL & HiFi API. Without this API, Tidal downloads wouldn't exist!",
+  "aboutBinimumDesc": "The creator of QQDL & HiFi API. This project helped shape lossless download support.",
   "@aboutBinimumDesc": {
     "description": "Credit description for binimum"
   },
-  "aboutSachinsenalDesc": "The original HiFi project creator. The foundation of Tidal integration!",
+  "aboutSachinsenalDesc": "The original HiFi project creator. A foundation for lossless-source integration.",
   "@aboutSachinsenalDesc": {
     "description": "Credit description for sachinsenal0x64"
   },
@@ -999,9 +978,9 @@
   "@providerPriorityInfo": {
     "description": "Info tip about fallback behavior"
   },
-  "providerBuiltIn": "Built-in",
+  "providerBuiltIn": "Legacy",
   "@providerBuiltIn": {
-    "description": "Label for built-in providers (Tidal/Qobuz)"
+    "description": "Legacy label retained for old generated localization compatibility"
   },
   "providerExtension": "Extension",
   "@providerExtension": {
@@ -1394,11 +1373,11 @@
   "@storeClearFilters": {
     "description": "Button to clear all filters"
   },
-  "extensionDefaultProvider": "Default (Deezer/Spotify)",
+  "extensionDefaultProvider": "Default Search",
   "@extensionDefaultProvider": {
     "description": "Default search provider option"
   },
-  "extensionDefaultProviderSubtitle": "Use built-in search",
+  "extensionDefaultProviderSubtitle": "Use the default metadata search",
   "@extensionDefaultProviderSubtitle": {
     "description": "Subtitle for default provider"
   },
@@ -1613,6 +1592,10 @@
   "@downloadAlbumFolderStructure": {
     "description": "Setting - album folder organization"
   },
+  "albumFolderStructureDescription": "Choose how album folders are structured",
+  "@albumFolderStructureDescription": {
+    "description": "Album folder structure picker description"
+  },
   "downloadSelectQuality": "Select Quality",
   "@downloadSelectQuality": {
     "description": "Dialog title - choose audio quality"
@@ -2071,43 +2054,43 @@
   },
   "downloadLossy320": "Lossy 320kbps",
   "@downloadLossy320": {
-    "description": "Quality option label for Tidal lossy 320kbps"
+    "description": "Quality option label for lossy 320kbps"
   },
   "downloadLossyFormat": "Lossy Format",
   "@downloadLossyFormat": {
-    "description": "Setting title to pick output format for Tidal lossy downloads"
+    "description": "Setting title to pick output format for lossy downloads"
   },
   "downloadLossy320Format": "Lossy 320kbps Format",
   "@downloadLossy320Format": {
-    "description": "Title of the Tidal lossy format picker bottom sheet"
+    "description": "Title of the lossy format picker bottom sheet"
   },
-  "downloadLossy320FormatDesc": "Choose the output format for Tidal 320kbps lossy downloads. The original AAC stream will be converted to your selected format.",
+  "downloadLossy320FormatDesc": "Choose the output format for 320kbps lossy downloads. The original stream will be converted to your selected format when needed.",
   "@downloadLossy320FormatDesc": {
-    "description": "Description in the Tidal lossy format picker"
+    "description": "Description in the lossy format picker"
   },
   "downloadLossyMp3": "MP3 320kbps",
   "@downloadLossyMp3": {
-    "description": "Tidal lossy format option - MP3 320kbps"
+    "description": "lossy format option - MP3 320kbps"
   },
   "downloadLossyMp3Subtitle": "Best compatibility, ~10MB per track",
   "@downloadLossyMp3Subtitle": {
-    "description": "Subtitle for MP3 320kbps Tidal lossy option"
+    "description": "Subtitle for MP3 320kbps lossy option"
   },
   "downloadLossyOpus256": "Opus 256kbps",
   "@downloadLossyOpus256": {
-    "description": "Tidal lossy format option - Opus 256kbps"
+    "description": "lossy format option - Opus 256kbps"
   },
   "downloadLossyOpus256Subtitle": "Best quality Opus, ~8MB per track",
   "@downloadLossyOpus256Subtitle": {
-    "description": "Subtitle for Opus 256kbps Tidal lossy option"
+    "description": "Subtitle for Opus 256kbps lossy option"
   },
   "downloadLossyOpus128": "Opus 128kbps",
   "@downloadLossyOpus128": {
-    "description": "Tidal lossy format option - Opus 128kbps"
+    "description": "lossy format option - Opus 128kbps"
   },
   "downloadLossyOpus128Subtitle": "Smallest size, ~4MB per track",
   "@downloadLossyOpus128Subtitle": {
-    "description": "Subtitle for Opus 128kbps Tidal lossy option"
+    "description": "Subtitle for Opus 128kbps lossy option"
   },
   "downloadUseAlbumArtistForFolders": "Use Album Artist for folders",
   "@downloadUseAlbumArtistForFolders": {
@@ -2697,7 +2680,7 @@
   "@tutorialWelcomeTip1": {
     "description": "Tutorial welcome tip 1"
   },
-  "tutorialWelcomeTip2": "Get FLAC quality audio from Tidal, Qobuz, or Deezer",
+  "tutorialWelcomeTip2": "Get FLAC quality audio from installed download extensions",
   "@tutorialWelcomeTip2": {
     "description": "Tutorial welcome tip 2"
   },
@@ -3600,7 +3583,7 @@
   "@lyricsProvidersDescription": {
     "description": "Description on the lyrics provider priority page"
   },
-  "lyricsProvidersInfoText": "Extension lyrics providers always run before built-in providers. At least one provider must remain enabled.",
+  "lyricsProvidersInfoText": "Extension lyrics providers run before built-in lyrics providers. At least one provider must remain enabled.",
   "@lyricsProvidersInfoText": {
     "description": "Info tip on lyrics provider priority page"
   },
@@ -3838,13 +3821,13 @@
   "@downloadNetworkCompatibilityModeDisabled": {
     "description": "Subtitle when network compatibility mode is off"
   },
-  "downloadSelectServiceToEnable": "Select Tidal or Qobuz to enable this option",
+  "downloadSelectServiceToEnable": "Select a provider with quality options to enable this option",
   "@downloadSelectServiceToEnable": {
     "description": "Subtitle when quality picker is disabled due to extension service"
   },
-  "downloadSelectTidalQobuz": "Select Tidal or Qobuz to choose audio quality",
+  "downloadSelectTidalQobuz": "Select a provider with quality options to choose audio quality",
   "@downloadSelectTidalQobuz": {
-    "description": "Info shown when a non-built-in service is selected"
+    "description": "Legacy info shown when a provider does not expose quality options"
   },
   "downloadEmbedLyricsDisabled": "Enable metadata embedding first",
   "@downloadEmbedLyricsDisabled": {
@@ -4206,7 +4189,7 @@
   },
   "extensionsSearchWith": "Search with {providerName}",
   "@extensionsSearchWith": {
-    "description": "Extensions page - subtitle for built-in search provider option",
+    "description": "Extensions page - subtitle for default metadata search provider option",
     "placeholders": {
       "providerName": {
         "type": "String"

lib/l10n/arb/app_pt.arb

@@ -142,9 +142,9 @@
       }
     }
   },
-  "optionsSwitchBack": "Tap Deezer or Spotify to switch back from extension",
+  "optionsSwitchBack": "Choose the default search provider to switch back from an extension",
   "@optionsSwitchBack": {
-    "description": "Hint to switch back to built-in providers"
+    "description": "Hint to switch back from extension search"
   },
   "optionsAutoFallback": "Auto Fallback",
   "@optionsAutoFallback": {
@@ -156,15 +156,15 @@
   },
   "optionsUseExtensionProviders": "Use Extension Providers",
   "@optionsUseExtensionProviders": {
-    "description": "Enable extension download providers"
+    "description": "Legacy setting label for extension download providers"
   },
-  "optionsUseExtensionProvidersOn": "Extensions will be tried first",
+  "optionsUseExtensionProvidersOn": "Extension providers are enabled",
   "@optionsUseExtensionProvidersOn": {
     "description": "Status when extension providers enabled"
   },
-  "optionsUseExtensionProvidersOff": "Using built-in providers only",
+  "optionsUseExtensionProvidersOff": "Extension providers are required",
   "@optionsUseExtensionProvidersOff": {
-    "description": "Status when extension providers disabled"
+    "description": "Legacy status when extension providers would be disabled"
   },
   "optionsEmbedLyrics": "Embed Lyrics",
   "@optionsEmbedLyrics": {
@@ -182,27 +182,6 @@
   "@optionsMaxQualityCoverSubtitle": {
     "description": "Subtitle for max quality cover"
   },
-  "optionsConcurrentDownloads": "Concurrent Downloads",
-  "@optionsConcurrentDownloads": {
-    "description": "Number of parallel downloads"
-  },
-  "optionsConcurrentSequential": "Sequential (1 at a time)",
-  "@optionsConcurrentSequential": {
-    "description": "Download one at a time"
-  },
-  "optionsConcurrentParallel": "{count} parallel downloads",
-  "@optionsConcurrentParallel": {
-    "description": "Multiple parallel downloads",
-    "placeholders": {
-      "count": {
-        "type": "int"
-      }
-    }
-  },
-  "optionsConcurrentWarning": "Parallel downloads may trigger rate limiting",
-  "@optionsConcurrentWarning": {
-    "description": "Warning about rate limits"
-  },
   "optionsExtensionStore": "Extension Store",
   "@optionsExtensionStore": {
     "description": "Show/hide store tab"
@@ -390,11 +369,11 @@
   "@aboutVersion": {
     "description": "Version info label"
   },
-  "aboutBinimumDesc": "The creator of QQDL & HiFi API. Without this API, Tidal downloads wouldn't exist!",
+  "aboutBinimumDesc": "The creator of QQDL & HiFi API. This project helped shape lossless download support.",
   "@aboutBinimumDesc": {
     "description": "Credit description for binimum"
   },
-  "aboutSachinsenalDesc": "The original HiFi project creator. The foundation of Tidal integration!",
+  "aboutSachinsenalDesc": "The original HiFi project creator. A foundation for lossless-source integration.",
   "@aboutSachinsenalDesc": {
     "description": "Credit description for sachinsenal0x64"
   },
@@ -999,9 +978,9 @@
   "@providerPriorityInfo": {
     "description": "Info tip about fallback behavior"
   },
-  "providerBuiltIn": "Built-in",
+  "providerBuiltIn": "Legacy",
   "@providerBuiltIn": {
-    "description": "Label for built-in providers (Tidal/Qobuz)"
+    "description": "Legacy label retained for old generated localization compatibility"
   },
   "providerExtension": "Extension",
   "@providerExtension": {
@@ -1394,11 +1373,11 @@
   "@storeClearFilters": {
     "description": "Button to clear all filters"
   },
-  "extensionDefaultProvider": "Default (Deezer/Spotify)",
+  "extensionDefaultProvider": "Default Search",
   "@extensionDefaultProvider": {
     "description": "Default search provider option"
   },
-  "extensionDefaultProviderSubtitle": "Use built-in search",
+  "extensionDefaultProviderSubtitle": "Use the default metadata search",
   "@extensionDefaultProviderSubtitle": {
     "description": "Subtitle for default provider"
   },
@@ -1613,6 +1592,10 @@
   "@downloadAlbumFolderStructure": {
     "description": "Setting - album folder organization"
   },
+  "albumFolderStructureDescription": "Choose how album folders are structured",
+  "@albumFolderStructureDescription": {
+    "description": "Album folder structure picker description"
+  },
   "downloadSelectQuality": "Select Quality",
   "@downloadSelectQuality": {
     "description": "Dialog title - choose audio quality"
@@ -2071,43 +2054,43 @@
   },
   "downloadLossy320": "Lossy 320kbps",
   "@downloadLossy320": {
-    "description": "Quality option label for Tidal lossy 320kbps"
+    "description": "Quality option label for lossy 320kbps"
   },
   "downloadLossyFormat": "Lossy Format",
   "@downloadLossyFormat": {
-    "description": "Setting title to pick output format for Tidal lossy downloads"
+    "description": "Setting title to pick output format for lossy downloads"
   },
   "downloadLossy320Format": "Lossy 320kbps Format",
   "@downloadLossy320Format": {
-    "description": "Title of the Tidal lossy format picker bottom sheet"
+    "description": "Title of the lossy format picker bottom sheet"
   },
-  "downloadLossy320FormatDesc": "Choose the output format for Tidal 320kbps lossy downloads. The original AAC stream will be converted to your selected format.",
+  "downloadLossy320FormatDesc": "Choose the output format for 320kbps lossy downloads. The original stream will be converted to your selected format when needed.",
   "@downloadLossy320FormatDesc": {
-    "description": "Description in the Tidal lossy format picker"
+    "description": "Description in the lossy format picker"
   },
   "downloadLossyMp3": "MP3 320kbps",
   "@downloadLossyMp3": {
-    "description": "Tidal lossy format option - MP3 320kbps"
+    "description": "lossy format option - MP3 320kbps"
   },
   "downloadLossyMp3Subtitle": "Best compatibility, ~10MB per track",
   "@downloadLossyMp3Subtitle": {
-    "description": "Subtitle for MP3 320kbps Tidal lossy option"
+    "description": "Subtitle for MP3 320kbps lossy option"
   },
   "downloadLossyOpus256": "Opus 256kbps",
   "@downloadLossyOpus256": {
-    "description": "Tidal lossy format option - Opus 256kbps"
+    "description": "lossy format option - Opus 256kbps"
   },
   "downloadLossyOpus256Subtitle": "Best quality Opus, ~8MB per track",
   "@downloadLossyOpus256Subtitle": {
-    "description": "Subtitle for Opus 256kbps Tidal lossy option"
+    "description": "Subtitle for Opus 256kbps lossy option"
   },
   "downloadLossyOpus128": "Opus 128kbps",
   "@downloadLossyOpus128": {
-    "description": "Tidal lossy format option - Opus 128kbps"
+    "description": "lossy format option - Opus 128kbps"
   },
   "downloadLossyOpus128Subtitle": "Smallest size, ~4MB per track",
   "@downloadLossyOpus128Subtitle": {
-    "description": "Subtitle for Opus 128kbps Tidal lossy option"
+    "description": "Subtitle for Opus 128kbps lossy option"
   },
   "downloadUseAlbumArtistForFolders": "Use Album Artist for folders",
   "@downloadUseAlbumArtistForFolders": {
@@ -2697,7 +2680,7 @@
   "@tutorialWelcomeTip1": {
     "description": "Tutorial welcome tip 1"
   },
-  "tutorialWelcomeTip2": "Get FLAC quality audio from Tidal, Qobuz, or Deezer",
+  "tutorialWelcomeTip2": "Get FLAC quality audio from installed download extensions",
   "@tutorialWelcomeTip2": {
     "description": "Tutorial welcome tip 2"
   },
@@ -3600,7 +3583,7 @@
   "@lyricsProvidersDescription": {
     "description": "Description on the lyrics provider priority page"
   },
-  "lyricsProvidersInfoText": "Extension lyrics providers always run before built-in providers. At least one provider must remain enabled.",
+  "lyricsProvidersInfoText": "Extension lyrics providers run before built-in lyrics providers. At least one provider must remain enabled.",
   "@lyricsProvidersInfoText": {
     "description": "Info tip on lyrics provider priority page"
   },
@@ -3838,13 +3821,13 @@
   "@downloadNetworkCompatibilityModeDisabled": {
     "description": "Subtitle when network compatibility mode is off"
   },
-  "downloadSelectServiceToEnable": "Select Tidal or Qobuz to enable this option",
+  "downloadSelectServiceToEnable": "Select a provider with quality options to enable this option",
   "@downloadSelectServiceToEnable": {
     "description": "Subtitle when quality picker is disabled due to extension service"
   },
-  "downloadSelectTidalQobuz": "Select Tidal or Qobuz to choose audio quality",
+  "downloadSelectTidalQobuz": "Select a provider with quality options to choose audio quality",
   "@downloadSelectTidalQobuz": {
-    "description": "Info shown when a non-built-in service is selected"
+    "description": "Legacy info shown when a provider does not expose quality options"
   },
   "downloadEmbedLyricsDisabled": "Enable metadata embedding first",
   "@downloadEmbedLyricsDisabled": {
@@ -4206,7 +4189,7 @@
   },
   "extensionsSearchWith": "Search with {providerName}",
   "@extensionsSearchWith": {
-    "description": "Extensions page - subtitle for built-in search provider option",
+    "description": "Extensions page - subtitle for default metadata search provider option",
     "placeholders": {
       "providerName": {
         "type": "String"

lib/l10n/arb/app_zh.arb

@@ -142,9 +142,9 @@
       }
     }
   },
-  "optionsSwitchBack": "Tap Deezer or Spotify to switch back from extension",
+  "optionsSwitchBack": "Choose the default search provider to switch back from an extension",
   "@optionsSwitchBack": {
-    "description": "Hint to switch back to built-in providers"
+    "description": "Hint to switch back from extension search"
   },
   "optionsAutoFallback": "Auto Fallback",
   "@optionsAutoFallback": {
@@ -156,15 +156,15 @@
   },
   "optionsUseExtensionProviders": "Use Extension Providers",
   "@optionsUseExtensionProviders": {
-    "description": "Enable extension download providers"
+    "description": "Legacy setting label for extension download providers"
   },
-  "optionsUseExtensionProvidersOn": "Extensions will be tried first",
+  "optionsUseExtensionProvidersOn": "Extension providers are enabled",
   "@optionsUseExtensionProvidersOn": {
     "description": "Status when extension providers enabled"
   },
-  "optionsUseExtensionProvidersOff": "Using built-in providers only",
+  "optionsUseExtensionProvidersOff": "Extension providers are required",
   "@optionsUseExtensionProvidersOff": {
-    "description": "Status when extension providers disabled"
+    "description": "Legacy status when extension providers would be disabled"
   },
   "optionsEmbedLyrics": "Embed Lyrics",
   "@optionsEmbedLyrics": {
@@ -182,27 +182,6 @@
   "@optionsMaxQualityCoverSubtitle": {
     "description": "Subtitle for max quality cover"
   },
-  "optionsConcurrentDownloads": "Concurrent Downloads",
-  "@optionsConcurrentDownloads": {
-    "description": "Number of parallel downloads"
-  },
-  "optionsConcurrentSequential": "Sequential (1 at a time)",
-  "@optionsConcurrentSequential": {
-    "description": "Download one at a time"
-  },
-  "optionsConcurrentParallel": "{count} parallel downloads",
-  "@optionsConcurrentParallel": {
-    "description": "Multiple parallel downloads",
-    "placeholders": {
-      "count": {
-        "type": "int"
-      }
-    }
-  },
-  "optionsConcurrentWarning": "Parallel downloads may trigger rate limiting",
-  "@optionsConcurrentWarning": {
-    "description": "Warning about rate limits"
-  },
   "optionsExtensionStore": "Extension Store",
   "@optionsExtensionStore": {
     "description": "Show/hide store tab"
@@ -390,11 +369,11 @@
   "@aboutVersion": {
     "description": "Version info label"
   },
-  "aboutBinimumDesc": "The creator of QQDL & HiFi API. Without this API, Tidal downloads wouldn't exist!",
+  "aboutBinimumDesc": "The creator of QQDL & HiFi API. This project helped shape lossless download support.",
   "@aboutBinimumDesc": {
     "description": "Credit description for binimum"
   },
-  "aboutSachinsenalDesc": "The original HiFi project creator. The foundation of Tidal integration!",
+  "aboutSachinsenalDesc": "The original HiFi project creator. A foundation for lossless-source integration.",
   "@aboutSachinsenalDesc": {
     "description": "Credit description for sachinsenal0x64"
   },
@@ -999,9 +978,9 @@
   "@providerPriorityInfo": {
     "description": "Info tip about fallback behavior"
   },
-  "providerBuiltIn": "Built-in",
+  "providerBuiltIn": "Legacy",
   "@providerBuiltIn": {
-    "description": "Label for built-in providers (Tidal/Qobuz)"
+    "description": "Legacy label retained for old generated localization compatibility"
   },
   "providerExtension": "Extension",
   "@providerExtension": {
@@ -1394,11 +1373,11 @@
   "@storeClearFilters": {
     "description": "Button to clear all filters"
   },
-  "extensionDefaultProvider": "Default (Deezer/Spotify)",
+  "extensionDefaultProvider": "Default Search",
   "@extensionDefaultProvider": {
     "description": "Default search provider option"
   },
-  "extensionDefaultProviderSubtitle": "Use built-in search",
+  "extensionDefaultProviderSubtitle": "Use the default metadata search",
   "@extensionDefaultProviderSubtitle": {
     "description": "Subtitle for default provider"
   },
@@ -1613,6 +1592,10 @@
   "@downloadAlbumFolderStructure": {
     "description": "Setting - album folder organization"
   },
+  "albumFolderStructureDescription": "Choose how album folders are structured",
+  "@albumFolderStructureDescription": {
+    "description": "Album folder structure picker description"
+  },
   "downloadSelectQuality": "Select Quality",
   "@downloadSelectQuality": {
     "description": "Dialog title - choose audio quality"
@@ -2071,43 +2054,43 @@
   },
   "downloadLossy320": "Lossy 320kbps",
   "@downloadLossy320": {
-    "description": "Quality option label for Tidal lossy 320kbps"
+    "description": "Quality option label for lossy 320kbps"
   },
   "downloadLossyFormat": "Lossy Format",
   "@downloadLossyFormat": {
-    "description": "Setting title to pick output format for Tidal lossy downloads"
+    "description": "Setting title to pick output format for lossy downloads"
   },
   "downloadLossy320Format": "Lossy 320kbps Format",
   "@downloadLossy320Format": {
-    "description": "Title of the Tidal lossy format picker bottom sheet"
+    "description": "Title of the lossy format picker bottom sheet"
   },
-  "downloadLossy320FormatDesc": "Choose the output format for Tidal 320kbps lossy downloads. The original AAC stream will be converted to your selected format.",
+  "downloadLossy320FormatDesc": "Choose the output format for 320kbps lossy downloads. The original stream will be converted to your selected format when needed.",
   "@downloadLossy320FormatDesc": {
-    "description": "Description in the Tidal lossy format picker"
+    "description": "Description in the lossy format picker"
   },
   "downloadLossyMp3": "MP3 320kbps",
   "@downloadLossyMp3": {
-    "description": "Tidal lossy format option - MP3 320kbps"
+    "description": "lossy format option - MP3 320kbps"
   },
   "downloadLossyMp3Subtitle": "Best compatibility, ~10MB per track",
   "@downloadLossyMp3Subtitle": {
-    "description": "Subtitle for MP3 320kbps Tidal lossy option"
+    "description": "Subtitle for MP3 320kbps lossy option"
   },
   "downloadLossyOpus256": "Opus 256kbps",
   "@downloadLossyOpus256": {
-    "description": "Tidal lossy format option - Opus 256kbps"
+    "description": "lossy format option - Opus 256kbps"
   },
   "downloadLossyOpus256Subtitle": "Best quality Opus, ~8MB per track",
   "@downloadLossyOpus256Subtitle": {
-    "description": "Subtitle for Opus 256kbps Tidal lossy option"
+    "description": "Subtitle for Opus 256kbps lossy option"
   },
   "downloadLossyOpus128": "Opus 128kbps",
   "@downloadLossyOpus128": {
-    "description": "Tidal lossy format option - Opus 128kbps"
+    "description": "lossy format option - Opus 128kbps"
   },
   "downloadLossyOpus128Subtitle": "Smallest size, ~4MB per track",
   "@downloadLossyOpus128Subtitle": {
-    "description": "Subtitle for Opus 128kbps Tidal lossy option"
+    "description": "Subtitle for Opus 128kbps lossy option"
   },
   "downloadUseAlbumArtistForFolders": "Use Album Artist for folders",
   "@downloadUseAlbumArtistForFolders": {
@@ -2697,7 +2680,7 @@
   "@tutorialWelcomeTip1": {
     "description": "Tutorial welcome tip 1"
   },
-  "tutorialWelcomeTip2": "Get FLAC quality audio from Tidal, Qobuz, or Deezer",
+  "tutorialWelcomeTip2": "Get FLAC quality audio from installed download extensions",
   "@tutorialWelcomeTip2": {
     "description": "Tutorial welcome tip 2"
   },
@@ -3600,7 +3583,7 @@
   "@lyricsProvidersDescription": {
     "description": "Description on the lyrics provider priority page"
   },
-  "lyricsProvidersInfoText": "Extension lyrics providers always run before built-in providers. At least one provider must remain enabled.",
+  "lyricsProvidersInfoText": "Extension lyrics providers run before built-in lyrics providers. At least one provider must remain enabled.",
   "@lyricsProvidersInfoText": {
     "description": "Info tip on lyrics provider priority page"
   },
@@ -3838,13 +3821,13 @@
   "@downloadNetworkCompatibilityModeDisabled": {
     "description": "Subtitle when network compatibility mode is off"
   },
-  "downloadSelectServiceToEnable": "Select Tidal or Qobuz to enable this option",
+  "downloadSelectServiceToEnable": "Select a provider with quality options to enable this option",
   "@downloadSelectServiceToEnable": {
     "description": "Subtitle when quality picker is disabled due to extension service"
   },
-  "downloadSelectTidalQobuz": "Select Tidal or Qobuz to choose audio quality",
+  "downloadSelectTidalQobuz": "Select a provider with quality options to choose audio quality",
   "@downloadSelectTidalQobuz": {
-    "description": "Info shown when a non-built-in service is selected"
+    "description": "Legacy info shown when a provider does not expose quality options"
   },
   "downloadEmbedLyricsDisabled": "Enable metadata embedding first",
   "@downloadEmbedLyricsDisabled": {
@@ -4206,7 +4189,7 @@
   },
   "extensionsSearchWith": "Search with {providerName}",
   "@extensionsSearchWith": {
-    "description": "Extensions page - subtitle for built-in search provider option",
+    "description": "Extensions page - subtitle for default metadata search provider option",
     "placeholders": {
       "providerName": {
         "type": "String"

lib/l10n/supported_locales.dart

@@ -14,23 +14,27 @@ const int translationThreshold = 70;
 /// Only these languages will be available in the app.
 const List<Locale> filteredSupportedLocales = <Locale>[
   Locale('en'),
-  Locale('ru'),
+  Locale('fr'),
+  Locale('de'),
   Locale('es', 'ES'),
-  Locale('id'),
-  Locale('pt', 'PT'),
-  Locale('ja'),
-  Locale('tr'),
   Locale('uk'),
+  Locale('ru'),
+  Locale('tr'),
+  Locale('id'),
+  Locale('ja'),
+  Locale('pt', 'PT'),
 ];
 
 /// Set of locale codes for quick lookup.
 const Set<String> filteredLocaleCodes = <String>{
   'en',
-  'ru',
+  'fr',
+  'de',
   'es_ES',
-  'id',
-  'pt_PT',
-  'ja',
-  'tr',
   'uk',
+  'ru',
+  'tr',
+  'id',
+  'ja',
+  'pt_PT',
 };

lib/main.dart

@@ -15,20 +15,43 @@ import 'package:spotiflac_android/services/notification_service.dart';
 import 'package:spotiflac_android/services/share_intent_service.dart';
 import 'package:spotiflac_android/services/cover_cache_manager.dart';
 import 'package:spotiflac_android/utils/local_library_scan_prefs.dart';
+import 'package:spotiflac_android/utils/logger.dart';
 
-void main() async {
-  WidgetsFlutterBinding.ensureInitialized();
-  final runtimeProfile = await _resolveRuntimeProfile();
-  _configureImageCache(runtimeProfile);
+final _log = AppLogger('Main');
 
-  runApp(
-    ProviderScope(
-      child: _EagerInitialization(
-        child: SpotiFLACApp(
-          disableOverscrollEffects: runtimeProfile.disableOverscrollEffects,
+void main() {
+  // Catch uncaught Dart errors so a failing async path is logged, not fatal.
+  // Native (Go) crashes still can't be caught here.
+  runZonedGuarded(
+    () async {
+      WidgetsFlutterBinding.ensureInitialized();
+
+      final previousOnError = FlutterError.onError;
+      FlutterError.onError = (details) {
+        previousOnError?.call(details);
+        _log.e('Uncaught Flutter error: ${details.exceptionAsString()}');
+      };
+      WidgetsBinding.instance.platformDispatcher.onError = (error, stack) {
+        _log.e('Uncaught platform error: $error');
+        return true;
+      };
+
+      final runtimeProfile = await _resolveRuntimeProfile();
+      _configureImageCache(runtimeProfile);
+
+      runApp(
+        ProviderScope(
+          child: _EagerInitialization(
+            child: SpotiFLACApp(
+              disableOverscrollEffects: runtimeProfile.disableOverscrollEffects,
+            ),
+          ),
         ),
-      ),
-    ),
+      );
+    },
+    (error, stack) {
+      _log.e('Uncaught zone error: $error');
+    },
   );
 }
 

lib/models/download_item.dart

@@ -12,7 +12,14 @@ enum DownloadStatus {
   skipped,
 }
 
-enum DownloadErrorType { unknown, notFound, rateLimit, network, permission }
+enum DownloadErrorType {
+  unknown,
+  notFound,
+  rateLimit,
+  network,
+  permission,
+  verificationRequired,
+}
 
 @JsonSerializable()
 class DownloadItem {
@@ -22,14 +29,15 @@ class DownloadItem {
   final DownloadStatus status;
   final double progress;
   final double speedMBps;
-  final int bytesReceived; // Bytes downloaded so far
+  final int bytesReceived;
   final int bytesTotal; // Total bytes when the server provides content length
   final String? filePath;
   final String? error;
   final DownloadErrorType? errorType;
   final DateTime createdAt;
-  final String? qualityOverride; // Override quality for this specific download
-  final String? playlistName; // Playlist context for folder organization
+  final String? qualityOverride;
+  final String? playlistName;
+  final int? playlistPosition; // 1-based position in the source playlist
 
   const DownloadItem({
     required this.id,
@@ -46,6 +54,7 @@ class DownloadItem {
     required this.createdAt,
     this.qualityOverride,
     this.playlistName,
+    this.playlistPosition,
   });
 
   DownloadItem copyWith({
@@ -63,6 +72,7 @@ class DownloadItem {
     DateTime? createdAt,
     String? qualityOverride,
     String? playlistName,
+    int? playlistPosition,
   }) {
     return DownloadItem(
       id: id ?? this.id,
@@ -79,6 +89,7 @@ class DownloadItem {
       createdAt: createdAt ?? this.createdAt,
       qualityOverride: qualityOverride ?? this.qualityOverride,
       playlistName: playlistName ?? this.playlistName,
+      playlistPosition: playlistPosition ?? this.playlistPosition,
     );
   }
 
@@ -94,6 +105,8 @@ class DownloadItem {
         return 'Connection failed, check your internet';
       case DownloadErrorType.permission:
         return 'Cannot write to folder, check storage permission';
+      case DownloadErrorType.verificationRequired:
+        return 'Verification required. Open the extension and complete the security check.';
       default:
         return error ?? 'An error occurred';
     }

lib/models/download_item.g.dart

@@ -23,6 +23,7 @@ DownloadItem _$DownloadItemFromJson(Map<String, dynamic> json) => DownloadItem(
   createdAt: DateTime.parse(json['createdAt'] as String),
   qualityOverride: json['qualityOverride'] as String?,
   playlistName: json['playlistName'] as String?,
+  playlistPosition: (json['playlistPosition'] as num?)?.toInt(),
 );
 
 Map<String, dynamic> _$DownloadItemToJson(DownloadItem instance) =>
@@ -41,6 +42,7 @@ Map<String, dynamic> _$DownloadItemToJson(DownloadItem instance) =>
       'createdAt': instance.createdAt.toIso8601String(),
       'qualityOverride': instance.qualityOverride,
       'playlistName': instance.playlistName,
+      'playlistPosition': instance.playlistPosition,
     };
 
 const _$DownloadStatusEnumMap = {
@@ -58,4 +60,5 @@ const _$DownloadErrorTypeEnumMap = {
   DownloadErrorType.rateLimit: 'rateLimit',
   DownloadErrorType.network: 'network',
   DownloadErrorType.permission: 'permission',
+  DownloadErrorType.verificationRequired: 'verificationRequired',
 };

lib/models/settings.dart

@@ -15,14 +15,13 @@ class AppSettings {
   final String storageMode; // 'app' or 'saf'
   final String downloadTreeUri; // SAF persistable tree URI
   final bool autoFallback;
-  final bool embedMetadata; // Master switch for metadata/cover/lyrics embedding
+  final bool embedMetadata;
   final String
   artistTagMode; // 'joined' or 'split_vorbis' for Vorbis-based formats
   final bool embedLyrics;
-  final bool embedReplayGain; // Calculate and embed ReplayGain tags
+  final bool embedReplayGain;
   final bool maxQualityCover;
   final bool isFirstLaunch;
-  final int concurrentDownloads;
   final bool checkForUpdates;
   final String updateChannel;
   final bool hasSearchedBefore;
@@ -44,37 +43,37 @@ class AppSettings {
   final String singleFilenameFormat;
   final String albumFolderStructure;
   final bool showExtensionStore;
+  final String
+  extensionVerificationBrowserMode; // 'external_first' or 'in_app_first'
   final String locale;
   final String lyricsMode;
   final String
-  tidalHighFormat; // Format for Tidal HIGH quality: 'mp3_320', 'aac_320', 'opus_256', or 'opus_128'
+  tidalHighFormat; // Legacy key for 320kbps lossy output format: 'mp3_320', 'aac_320', 'opus_256', or 'opus_128'
   final bool
   useAllFilesAccess; // Android 13+ only: enable MANAGE_EXTERNAL_STORAGE
-  final bool
-  autoExportFailedDownloads; // Auto export failed downloads to TXT file
+  final bool autoExportFailedDownloads;
   final String
   downloadNetworkMode; // 'any' = WiFi + Mobile, 'wifi_only' = WiFi only
   final bool
   networkCompatibilityMode; // Try HTTP + allow invalid TLS cert for API requests
+  final bool
+  allowLocalNetwork; // Allow requests to private/local network targets (local proxy / custom DNS)
   final String
   songLinkRegion; // SongLink userCountry region code used for platform lookup
   final bool
   nativeDownloadWorkerEnabled; // Experimental Android service-owned worker
 
-  final bool localLibraryEnabled; // Enable local library scanning
-  final String localLibraryPath; // Path to scan for audio files
+  final bool localLibraryEnabled;
+  final String localLibraryPath;
   final String
   localLibraryBookmark; // Base64-encoded iOS security-scoped bookmark
-  final bool
-  localLibraryShowDuplicates; // Show indicator when searching for existing tracks
+  final bool localLibraryShowDuplicates;
   final String
   localLibraryAutoScan; // Auto-scan mode: 'off', 'on_open', 'daily', 'weekly'
 
-  final bool
-  hasCompletedTutorial; // Track if user has completed the app tutorial
+  final bool hasCompletedTutorial;
 
-  final List<String>
-  lyricsProviders; // Ordered list of enabled lyrics provider IDs
+  final List<String> lyricsProviders;
   final bool
   lyricsIncludeTranslationNetease; // Append translated lyrics (Netease)
   final bool
@@ -89,9 +88,10 @@ class AppSettings {
   final String
   lastSeenVersion; // Last app version the user has acknowledged (e.g. '3.7.0')
 
-  final bool
-  deduplicateDownloads; // Skip downloading tracks already present in history
-  final bool saveDownloadHistory; // Record completed downloads in local history
+  final bool deduplicateDownloads;
+  final bool saveDownloadHistory;
+
+  final String playerMode;
 
   const AppSettings({
     this.defaultService = '',
@@ -108,7 +108,6 @@ class AppSettings {
     this.embedReplayGain = false,
     this.maxQualityCover = true,
     this.isFirstLaunch = true,
-    this.concurrentDownloads = 1,
     this.checkForUpdates = true,
     this.updateChannel = 'stable',
     this.hasSearchedBefore = false,
@@ -130,6 +129,7 @@ class AppSettings {
     this.singleFilenameFormat = '{title} - {artist}',
     this.albumFolderStructure = 'artist_album',
     this.showExtensionStore = true,
+    this.extensionVerificationBrowserMode = 'in_app_first',
     this.locale = 'system',
     this.lyricsMode = 'embed',
     this.tidalHighFormat = 'mp3_320',
@@ -137,6 +137,7 @@ class AppSettings {
     this.autoExportFailedDownloads = false,
     this.downloadNetworkMode = 'any',
     this.networkCompatibilityMode = false,
+    this.allowLocalNetwork = false,
     this.songLinkRegion = 'US',
     this.nativeDownloadWorkerEnabled = false,
     this.localLibraryEnabled = false,
@@ -154,6 +155,7 @@ class AppSettings {
     this.lastSeenVersion = '',
     this.deduplicateDownloads = true,
     this.saveDownloadHistory = true,
+    this.playerMode = 'external',
   });
 
   AppSettings copyWith({
@@ -171,7 +173,6 @@ class AppSettings {
     bool? embedReplayGain,
     bool? maxQualityCover,
     bool? isFirstLaunch,
-    int? concurrentDownloads,
     bool? checkForUpdates,
     String? updateChannel,
     bool? hasSearchedBefore,
@@ -196,6 +197,7 @@ class AppSettings {
     String? singleFilenameFormat,
     String? albumFolderStructure,
     bool? showExtensionStore,
+    String? extensionVerificationBrowserMode,
     String? locale,
     String? lyricsMode,
     String? tidalHighFormat,
@@ -203,6 +205,7 @@ class AppSettings {
     bool? autoExportFailedDownloads,
     String? downloadNetworkMode,
     bool? networkCompatibilityMode,
+    bool? allowLocalNetwork,
     String? songLinkRegion,
     bool? nativeDownloadWorkerEnabled,
     bool? localLibraryEnabled,
@@ -220,6 +223,7 @@ class AppSettings {
     String? lastSeenVersion,
     bool? deduplicateDownloads,
     bool? saveDownloadHistory,
+    String? playerMode,
   }) {
     return AppSettings(
       defaultService: defaultService ?? this.defaultService,
@@ -237,7 +241,6 @@ class AppSettings {
       embedReplayGain: embedReplayGain ?? this.embedReplayGain,
       maxQualityCover: maxQualityCover ?? this.maxQualityCover,
       isFirstLaunch: isFirstLaunch ?? this.isFirstLaunch,
-      concurrentDownloads: concurrentDownloads ?? this.concurrentDownloads,
       checkForUpdates: checkForUpdates ?? this.checkForUpdates,
       updateChannel: updateChannel ?? this.updateChannel,
       hasSearchedBefore: hasSearchedBefore ?? this.hasSearchedBefore,
@@ -270,6 +273,9 @@ class AppSettings {
       singleFilenameFormat: singleFilenameFormat ?? this.singleFilenameFormat,
       albumFolderStructure: albumFolderStructure ?? this.albumFolderStructure,
       showExtensionStore: showExtensionStore ?? this.showExtensionStore,
+      extensionVerificationBrowserMode:
+          extensionVerificationBrowserMode ??
+          this.extensionVerificationBrowserMode,
       locale: locale ?? this.locale,
       lyricsMode: lyricsMode ?? this.lyricsMode,
       tidalHighFormat: tidalHighFormat ?? this.tidalHighFormat,
@@ -279,6 +285,7 @@ class AppSettings {
       downloadNetworkMode: downloadNetworkMode ?? this.downloadNetworkMode,
       networkCompatibilityMode:
           networkCompatibilityMode ?? this.networkCompatibilityMode,
+      allowLocalNetwork: allowLocalNetwork ?? this.allowLocalNetwork,
       songLinkRegion: songLinkRegion ?? this.songLinkRegion,
       nativeDownloadWorkerEnabled:
           nativeDownloadWorkerEnabled ?? this.nativeDownloadWorkerEnabled,
@@ -304,6 +311,7 @@ class AppSettings {
       lastSeenVersion: lastSeenVersion ?? this.lastSeenVersion,
       deduplicateDownloads: deduplicateDownloads ?? this.deduplicateDownloads,
       saveDownloadHistory: saveDownloadHistory ?? this.saveDownloadHistory,
+      playerMode: playerMode ?? this.playerMode,
     );
   }
 

lib/models/settings.g.dart

@@ -21,7 +21,6 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
   embedReplayGain: json['embedReplayGain'] as bool? ?? false,
   maxQualityCover: json['maxQualityCover'] as bool? ?? true,
   isFirstLaunch: json['isFirstLaunch'] as bool? ?? true,
-  concurrentDownloads: (json['concurrentDownloads'] as num?)?.toInt() ?? 1,
   checkForUpdates: json['checkForUpdates'] as bool? ?? true,
   updateChannel: json['updateChannel'] as String? ?? 'stable',
   hasSearchedBefore: json['hasSearchedBefore'] as bool? ?? false,
@@ -49,6 +48,8 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
   albumFolderStructure:
       json['albumFolderStructure'] as String? ?? 'artist_album',
   showExtensionStore: json['showExtensionStore'] as bool? ?? true,
+  extensionVerificationBrowserMode:
+      json['extensionVerificationBrowserMode'] as String? ?? 'in_app_first',
   locale: json['locale'] as String? ?? 'system',
   lyricsMode: json['lyricsMode'] as String? ?? 'embed',
   tidalHighFormat: json['tidalHighFormat'] as String? ?? 'mp3_320',
@@ -57,6 +58,7 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
       json['autoExportFailedDownloads'] as bool? ?? false,
   downloadNetworkMode: json['downloadNetworkMode'] as String? ?? 'any',
   networkCompatibilityMode: json['networkCompatibilityMode'] as bool? ?? false,
+  allowLocalNetwork: json['allowLocalNetwork'] as bool? ?? false,
   songLinkRegion: json['songLinkRegion'] as String? ?? 'US',
   nativeDownloadWorkerEnabled:
       json['nativeDownloadWorkerEnabled'] as bool? ?? false,
@@ -83,6 +85,7 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
   lastSeenVersion: json['lastSeenVersion'] as String? ?? '',
   deduplicateDownloads: json['deduplicateDownloads'] as bool? ?? true,
   saveDownloadHistory: json['saveDownloadHistory'] as bool? ?? true,
+  playerMode: json['playerMode'] as String? ?? 'external',
 );
 
 Map<String, dynamic> _$AppSettingsToJson(
@@ -102,7 +105,6 @@ Map<String, dynamic> _$AppSettingsToJson(
   'embedReplayGain': instance.embedReplayGain,
   'maxQualityCover': instance.maxQualityCover,
   'isFirstLaunch': instance.isFirstLaunch,
-  'concurrentDownloads': instance.concurrentDownloads,
   'checkForUpdates': instance.checkForUpdates,
   'updateChannel': instance.updateChannel,
   'hasSearchedBefore': instance.hasSearchedBefore,
@@ -125,6 +127,7 @@ Map<String, dynamic> _$AppSettingsToJson(
   'singleFilenameFormat': instance.singleFilenameFormat,
   'albumFolderStructure': instance.albumFolderStructure,
   'showExtensionStore': instance.showExtensionStore,
+  'extensionVerificationBrowserMode': instance.extensionVerificationBrowserMode,
   'locale': instance.locale,
   'lyricsMode': instance.lyricsMode,
   'tidalHighFormat': instance.tidalHighFormat,
@@ -132,6 +135,7 @@ Map<String, dynamic> _$AppSettingsToJson(
   'autoExportFailedDownloads': instance.autoExportFailedDownloads,
   'downloadNetworkMode': instance.downloadNetworkMode,
   'networkCompatibilityMode': instance.networkCompatibilityMode,
+  'allowLocalNetwork': instance.allowLocalNetwork,
   'songLinkRegion': instance.songLinkRegion,
   'nativeDownloadWorkerEnabled': instance.nativeDownloadWorkerEnabled,
   'localLibraryEnabled': instance.localLibraryEnabled,
@@ -149,4 +153,5 @@ Map<String, dynamic> _$AppSettingsToJson(
   'lastSeenVersion': instance.lastSeenVersion,
   'deduplicateDownloads': instance.deduplicateDownloads,
   'saveDownloadHistory': instance.saveDownloadHistory,
+  'playerMode': instance.playerMode,
 };

lib/models/track.dart

@@ -13,6 +13,7 @@ class Track {
   final String? albumId;
   final String? coverUrl;
   final String? isrc;
+  final String? previewUrl;
   final int duration;
   final int? trackNumber;
   final int? discNumber;
@@ -38,6 +39,7 @@ class Track {
     this.albumId,
     this.coverUrl,
     this.isrc,
+    this.previewUrl,
     required this.duration,
     this.trackNumber,
     this.discNumber,
@@ -81,6 +83,8 @@ class Track {
       audioModes != null && audioModes!.contains('DOLBY_ATMOS');
 
   bool get hasAudioQuality => audioQuality != null && audioQuality!.isNotEmpty;
+
+  bool get hasPreview => previewUrl != null && previewUrl!.isNotEmpty;
 }
 
 @JsonSerializable()

lib/models/track.g.dart

@@ -16,6 +16,7 @@ Track _$TrackFromJson(Map<String, dynamic> json) => Track(
   albumId: json['albumId'] as String?,
   coverUrl: json['coverUrl'] as String?,
   isrc: json['isrc'] as String?,
+  previewUrl: json['previewUrl'] as String?,
   duration: (json['duration'] as num).toInt(),
   trackNumber: (json['trackNumber'] as num?)?.toInt(),
   discNumber: (json['discNumber'] as num?)?.toInt(),
@@ -46,6 +47,7 @@ Map<String, dynamic> _$TrackToJson(Track instance) => <String, dynamic>{
   'albumId': instance.albumId,
   'coverUrl': instance.coverUrl,
   'isrc': instance.isrc,
+  'previewUrl': instance.previewUrl,
   'duration': instance.duration,
   'trackNumber': instance.trackNumber,
   'discNumber': instance.discNumber,

lib/providers/extension_provider.dart

@@ -14,6 +14,22 @@ final _log = AppLogger('ExtensionProvider');
 const _metadataProviderPriorityKey = 'metadata_provider_priority';
 const _providerPriorityKey = 'provider_priority';
 const _spotifyWebExtensionId = 'spotify-web';
+const _storeRegistryUrlPrefKey = 'store_registry_url';
+
+/// Result of restoring extensions from a backup.
+class ExtensionRestoreResult {
+  final int installed;
+  final int alreadyPresent;
+  final int failed;
+  final List<String> failedIds;
+
+  const ExtensionRestoreResult({
+    this.installed = 0,
+    this.alreadyPresent = 0,
+    this.failed = 0,
+    this.failedIds = const [],
+  });
+}
 
 bool _stringListEquals(List<String> a, List<String> b) {
   if (identical(a, b)) return true;
@@ -792,12 +808,15 @@ class ExtensionInstallBatchResult {
 }
 
 class ExtensionNotifier extends Notifier<ExtensionState> {
-  static const _extensionHealthCacheTtl = Duration(seconds: 60);
+  static const _extensionHealthDefaultCacheTtl = Duration(minutes: 10);
+  static const _extensionHealthMinimumCacheTtl = Duration(minutes: 1);
+  static const _extensionHealthUnknownCacheTtl = Duration(minutes: 2);
   AppLifecycleListener? _appLifecycleListener;
   bool _cleanupInFlight = false;
   Completer<void>? _initializationCompleter;
   final Map<String, DateTime> _healthExpiresAt = {};
   final Map<String, Future<ExtensionHealthStatus?>> _healthInFlight = {};
+  final Map<String, int> _healthRequestSerial = {};
 
   @override
   ExtensionState build() {
@@ -809,6 +828,7 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
       _appLifecycleListener = null;
       _healthExpiresAt.clear();
       _healthInFlight.clear();
+      _healthRequestSerial.clear();
     });
     return const ExtensionState();
   }
@@ -938,15 +958,46 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
     }
   }
 
-  void _scheduleExtensionHealthRefresh(List<Extension> extensions) {
+  void _scheduleExtensionHealthRefresh(
+    List<Extension> extensions, {
+    bool force = false,
+  }) {
     for (final ext in extensions) {
       if (!ext.enabled || !ext.hasServiceHealth) continue;
-      unawaited(checkExtensionHealth(ext.id));
+      unawaited(checkExtensionHealth(ext.id, force: force));
     }
   }
 
-  void refreshEnabledExtensionHealth() {
-    _scheduleExtensionHealthRefresh(state.extensions);
+  void refreshEnabledExtensionHealth({bool force = false}) {
+    _scheduleExtensionHealthRefresh(state.extensions, force: force);
+  }
+
+  Duration _extensionHealthCacheTtlFor(Extension extension) {
+    var ttl = _extensionHealthDefaultCacheTtl;
+    for (final check in extension.serviceHealth) {
+      final seconds = check.cacheTtlSeconds;
+      if (seconds == null || seconds <= 0) continue;
+
+      var checkTtl = Duration(seconds: seconds);
+      if (checkTtl < _extensionHealthMinimumCacheTtl) {
+        checkTtl = _extensionHealthMinimumCacheTtl;
+      }
+      if (checkTtl < ttl) {
+        ttl = checkTtl;
+      }
+    }
+    return ttl;
+  }
+
+  Duration _extensionHealthCacheTtlForStatus(
+    Extension extension,
+    String status,
+  ) {
+    final ttl = _extensionHealthCacheTtlFor(extension);
+    if (status == 'unknown' && ttl > _extensionHealthUnknownCacheTtl) {
+      return _extensionHealthUnknownCacheTtl;
+    }
+    return ttl;
   }
 
   Future<ExtensionHealthStatus?> checkExtensionHealth(
@@ -974,17 +1025,22 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
       return inFlight;
     }
 
+    final requestSerial = (_healthRequestSerial[extensionId] ?? 0) + 1;
+    _healthRequestSerial[extensionId] = requestSerial;
+
     final future = () async {
       try {
         final result = await PlatformBridge.checkExtensionHealth(extensionId);
         final status = ExtensionHealthStatus.fromJson(result);
-        final updated = Map<String, ExtensionHealthStatus>.of(
-          state.healthStatuses,
-        )..[extensionId] = status;
-        _healthExpiresAt[extensionId] = DateTime.now().add(
-          _extensionHealthCacheTtl,
-        );
-        state = state.copyWith(healthStatuses: updated);
+        if (_healthRequestSerial[extensionId] == requestSerial) {
+          final updated = Map<String, ExtensionHealthStatus>.of(
+            state.healthStatuses,
+          )..[extensionId] = status;
+          _healthExpiresAt[extensionId] = DateTime.now().add(
+            _extensionHealthCacheTtlForStatus(ext, status.status),
+          );
+          state = state.copyWith(healthStatuses: updated);
+        }
         return status;
       } catch (e) {
         _log.w('Failed to check extension health for $extensionId: $e');
@@ -994,16 +1050,20 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
           checkedAt: DateTime.now(),
           checks: const [],
         );
-        final updated = Map<String, ExtensionHealthStatus>.of(
-          state.healthStatuses,
-        )..[extensionId] = status;
-        _healthExpiresAt[extensionId] = DateTime.now().add(
-          const Duration(seconds: 20),
-        );
-        state = state.copyWith(healthStatuses: updated);
+        if (_healthRequestSerial[extensionId] == requestSerial) {
+          final updated = Map<String, ExtensionHealthStatus>.of(
+            state.healthStatuses,
+          )..[extensionId] = status;
+          _healthExpiresAt[extensionId] = DateTime.now().add(
+            _extensionHealthUnknownCacheTtl,
+          );
+          state = state.copyWith(healthStatuses: updated);
+        }
         return status;
       } finally {
-        _healthInFlight.remove(extensionId);
+        if (_healthRequestSerial[extensionId] == requestSerial) {
+          _healthInFlight.remove(extensionId);
+        }
       }
     }();
 
@@ -1283,20 +1343,20 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
         .firstOrNull;
   }
 
-  bool downloadProviderMatchesBuiltIn(
+  bool downloadProviderReplacesLegacyProvider(
     String providerId,
-    String builtInProviderId,
+    String legacyProviderId,
   ) {
     final normalizedProvider = providerId.trim().toLowerCase();
-    final normalizedBuiltIn = builtInProviderId.trim().toLowerCase();
-    if (normalizedProvider.isEmpty || normalizedBuiltIn.isEmpty) return false;
-    if (normalizedProvider == normalizedBuiltIn) return true;
+    final normalizedLegacy = legacyProviderId.trim().toLowerCase();
+    if (normalizedProvider.isEmpty || normalizedLegacy.isEmpty) return false;
+    if (normalizedProvider == normalizedLegacy) return true;
 
     final extension = state.extensions
         .where((ext) => ext.enabled && ext.hasDownloadProvider)
         .where((ext) => ext.id.toLowerCase() == normalizedProvider)
         .firstOrNull;
-    return extension?.replacesBuiltInProviders.contains(normalizedBuiltIn) ??
+    return extension?.replacesBuiltInProviders.contains(normalizedLegacy) ??
         false;
   }
 
@@ -1640,7 +1700,7 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
     }
   }
 
-  List<Extension> get enabledExtensions {
+  List<Extension> enabledExtensions() {
     return state.extensions.where((ext) => ext.enabled).toList();
   }
 
@@ -1717,11 +1777,208 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
     return result;
   }
 
-  List<Extension> get searchProviders {
+  List<Extension> searchProviders() {
     return state.extensions
         .where((ext) => ext.enabled && ext.hasCustomSearch)
         .toList();
   }
+
+  /// Collects the keys flagged as `secret` in an extension's manifest schema
+  /// (top-level settings and quality-specific settings).
+  Set<String> _secretKeysFromManifest(Map<String, dynamic> raw) {
+    final keys = <String>{};
+
+    void scan(Object? settingsList) {
+      if (settingsList is! List) return;
+      for (final entry in settingsList) {
+        if (entry is Map && entry['secret'] == true && entry['key'] is String) {
+          keys.add(entry['key'] as String);
+        }
+      }
+    }
+
+    scan(raw['settings']);
+    final quality = raw['quality_options'];
+    if (quality is List) {
+      for (final option in quality) {
+        if (option is Map) {
+          scan(option['settings']);
+        }
+      }
+    }
+    return keys;
+  }
+
+  /// Builds the extensions section of a backup: the store registry URL plus the
+  /// installed extensions with their id, version, enabled flag and settings.
+  /// Secret-flagged settings (tokens, API keys) are only included when
+  /// [includeSecrets] is true.
+  Future<Map<String, dynamic>> exportBackup({
+    required bool includeSecrets,
+  }) async {
+    if (!PlatformBridge.supportsExtensionSystem) {
+      return {'registry_url': '', 'items': const <Map<String, dynamic>>[]};
+    }
+
+    String registryUrl = '';
+    try {
+      registryUrl = await PlatformBridge.getStoreRegistryUrl();
+    } catch (_) {}
+
+    List<Map<String, dynamic>> installed;
+    try {
+      installed = await PlatformBridge.getInstalledExtensions();
+    } catch (e) {
+      _log.w('Backup: failed to list extensions: $e');
+      installed = const [];
+    }
+
+    final items = <Map<String, dynamic>>[];
+    for (final raw in installed) {
+      final id = raw['id'] as String?;
+      if (id == null || id.isEmpty) continue;
+      final secretKeys = _secretKeysFromManifest(raw);
+
+      Map<String, dynamic> settings = {};
+      try {
+        settings = await PlatformBridge.getExtensionSettings(id);
+      } catch (_) {}
+
+      final filtered = <String, dynamic>{};
+      var omittedSecret = false;
+      settings.forEach((key, value) {
+        if (secretKeys.contains(key)) {
+          if (!includeSecrets) {
+            omittedSecret = true;
+            return;
+          }
+        }
+        filtered[key] = value;
+      });
+
+      items.add({
+        'id': id,
+        'version': raw['version']?.toString() ?? '',
+        'enabled': raw['enabled'] == true,
+        'settings': filtered,
+        if (omittedSecret) 'secrets_omitted': true,
+      });
+    }
+
+    return {'registry_url': registryUrl, 'items': items};
+  }
+
+  /// Restores extensions from a backup section produced by [exportBackup]:
+  /// re-applies the store registry URL, reinstalls each extension from the
+  /// store when missing, then merges settings and restores the enabled flag.
+  /// Missing settings (e.g. omitted secrets) are merged with the current values
+  /// so they are not wiped.
+  Future<ExtensionRestoreResult> restoreFromBackup(
+    Map<String, dynamic> data,
+  ) async {
+    if (!PlatformBridge.supportsExtensionSystem) {
+      return const ExtensionRestoreResult();
+    }
+
+    final registryUrl = (data['registry_url'] as String?)?.trim() ?? '';
+    final itemsRaw = data['items'];
+    final items = itemsRaw is List
+        ? itemsRaw
+              .whereType<Map<Object?, Object?>>()
+              .map((e) => Map<String, dynamic>.from(e))
+              .toList()
+        : <Map<String, dynamic>>[];
+
+    Directory? destDir;
+    try {
+      final tmp = await getTemporaryDirectory();
+      destDir = await Directory(
+        '${tmp.path}/spotiflac_restore_ext',
+      ).create(recursive: true);
+      await PlatformBridge.initExtensionStore(destDir.path);
+      if (registryUrl.isNotEmpty) {
+        await PlatformBridge.setStoreRegistryUrl(registryUrl);
+        final prefs = await SharedPreferences.getInstance();
+        await prefs.setString(_storeRegistryUrlPrefKey, registryUrl);
+      }
+    } catch (e) {
+      _log.w('Restore: failed to prepare extension store: $e');
+    }
+
+    await refreshExtensions();
+    final installedIds = state.extensions
+        .map((e) => e.id.toLowerCase())
+        .toSet();
+
+    var installedCount = 0;
+    var alreadyPresent = 0;
+    var failed = 0;
+    final failedIds = <String>[];
+
+    for (final item in items) {
+      final id = item['id'] as String?;
+      if (id == null || id.isEmpty) continue;
+      final enabled = item['enabled'] != false;
+      var present = installedIds.contains(id.toLowerCase());
+
+      if (!present) {
+        if (destDir == null) {
+          failed++;
+          failedIds.add(id);
+          continue;
+        }
+        try {
+          final path = await PlatformBridge.downloadStoreExtension(
+            id,
+            destDir.path,
+          );
+          final ok = await installExtension(path);
+          if (ok) {
+            installedCount++;
+            present = true;
+          } else {
+            failed++;
+            failedIds.add(id);
+          }
+        } catch (e) {
+          _log.w('Restore: failed to install extension $id: $e');
+          failed++;
+          failedIds.add(id);
+        }
+      } else {
+        alreadyPresent++;
+      }
+
+      if (!present) continue;
+
+      final settings = item['settings'];
+      if (settings is Map && settings.isNotEmpty) {
+        try {
+          final current = await PlatformBridge.getExtensionSettings(id);
+          final merged = <String, dynamic>{
+            ...current,
+            ...Map<String, dynamic>.from(settings),
+          };
+          await PlatformBridge.setExtensionSettings(id, merged);
+        } catch (e) {
+          _log.w('Restore: failed to apply settings for $id: $e');
+        }
+      }
+
+      try {
+        await setExtensionEnabled(id, enabled);
+      } catch (_) {}
+    }
+
+    await refreshExtensions();
+
+    return ExtensionRestoreResult(
+      installed: installedCount,
+      alreadyPresent: alreadyPresent,
+      failed: failed,
+      failedIds: failedIds,
+    );
+  }
 }
 
 final extensionProvider = NotifierProvider<ExtensionNotifier, ExtensionState>(

lib/providers/library_collections_provider.dart

@@ -953,6 +953,90 @@ class LibraryCollectionsNotifier extends Notifier<LibraryCollectionsState> {
     });
     _invalidatePlaylistPickerSummaries();
   }
+
+  /// Returns the full collections snapshot (wishlist, loved, playlists,
+  /// favorite artists) for a backup, ensuring data is loaded first.
+  Future<Map<String, dynamic>> exportCollections() async {
+    await _ensureLoaded();
+    return state.toJson();
+  }
+
+  /// Exports custom playlist cover images as base64, keyed by playlist id.
+  /// Each value contains the original file extension and the encoded bytes so a
+  /// restore on another device can recreate the cover files.
+  Future<Map<String, Map<String, String>>> exportPlaylistCovers() async {
+    await _ensureLoaded();
+    final covers = <String, Map<String, String>>{};
+    for (final playlist in state.playlists) {
+      final path = playlist.coverImagePath;
+      if (path == null || path.isEmpty) continue;
+      try {
+        final file = File(path);
+        if (!await file.exists()) continue;
+        final bytes = await file.readAsBytes();
+        if (bytes.isEmpty) continue;
+        covers[playlist.id] = {
+          'ext': p.extension(path).toLowerCase(),
+          'data': base64Encode(bytes),
+        };
+      } catch (_) {
+        // Skip unreadable cover; the rest of the backup still succeeds.
+      }
+    }
+    return covers;
+  }
+
+  /// Replaces all collections (wishlist, loved, playlists, favorite artists)
+  /// with the contents of a backup. [collectionsJson] uses the
+  /// [LibraryCollectionsState.toJson] shape; [coverImages] is the map produced
+  /// by [exportPlaylistCovers]. Cover images are rewritten into this device's
+  /// covers directory and their paths fixed up before persisting.
+  Future<void> restoreFromBackup(
+    Map<String, dynamic> collectionsJson, {
+    Map<String, dynamic>? coverImages,
+  }) async {
+    final normalized = Map<String, dynamic>.from(collectionsJson);
+    final coversDir = await _playlistCoversDir();
+
+    final playlistsRaw = normalized['playlists'];
+    if (playlistsRaw is List) {
+      final rewritten = <Map<String, dynamic>>[];
+      for (final entry in playlistsRaw.whereType<Map<Object?, Object?>>()) {
+        final playlist = Map<String, dynamic>.from(entry);
+        final id = playlist['id'] as String?;
+        String? newCoverPath;
+        final coverEntry = (id != null && coverImages != null)
+            ? coverImages[id]
+            : null;
+        if (id != null && coverEntry is Map) {
+          final data = coverEntry['data'] as String?;
+          final ext = (coverEntry['ext'] as String?) ?? '.jpg';
+          if (data != null && data.isNotEmpty) {
+            try {
+              final destPath = p.join(coversDir.path, '$id$ext');
+              await File(destPath).writeAsBytes(base64Decode(data));
+              newCoverPath = destPath;
+            } catch (_) {
+              newCoverPath = null;
+            }
+          }
+        }
+        // Always replace the backup's device-specific path: either with the
+        // freshly written local cover, or drop it so a stale path is not kept.
+        if (newCoverPath != null) {
+          playlist['coverImagePath'] = newCoverPath;
+        } else {
+          playlist.remove('coverImagePath');
+        }
+        rewritten.add(playlist);
+      }
+      normalized['playlists'] = rewritten;
+    }
+
+    await _db.replaceAllFromBackup(normalized);
+    await _load();
+    _invalidatePlaylistPickerSummaries();
+  }
 }
 
 final libraryCollectionsProvider =

lib/providers/music_player_provider.dart

@@ -0,0 +1,153 @@
+import 'package:audio_service/audio_service.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:spotiflac_android/providers/download_queue_provider.dart';
+import 'package:spotiflac_android/services/library_database.dart';
+import 'package:spotiflac_android/services/music_player_service.dart';
+
+final currentMediaItemProvider = StreamProvider<MediaItem?>((ref) {
+  return musicPlayerMediaItemEvents();
+});
+
+final playbackStateProvider = StreamProvider<PlaybackState>((ref) {
+  return musicPlayerPlaybackStateEvents();
+});
+
+final playQueueProvider = StreamProvider<List<MediaItem>>((ref) {
+  return musicPlayerQueueEvents();
+});
+
+class MusicPlayerController {
+  const MusicPlayerController();
+
+  MusicPlayerHandler? get _handler => musicPlayerHandler;
+
+  bool get isAvailable => _handler != null;
+
+  Future<MusicPlayerHandler?> ensureInitialized() async {
+    try {
+      return await initMusicPlayer();
+    } catch (_) {
+      return null;
+    }
+  }
+
+  Future<void> playAll(
+    List<PlayableMedia> items, {
+    int initialIndex = 0,
+  }) async {
+    final handler = await ensureInitialized();
+    await handler?.setQueueAndPlay(items, initialIndex: initialIndex);
+  }
+
+  Future<void> playSingle(PlayableMedia item) => playAll([item]);
+
+  Future<void> playHistory(
+    List<DownloadHistoryItem> items, {
+    int initialIndex = 0,
+  }) async {
+    final media = items
+        .where((i) => i.filePath.trim().isNotEmpty)
+        .map(playableFromHistory)
+        .toList();
+    if (media.isEmpty) return;
+    await playAll(media, initialIndex: initialIndex.clamp(0, media.length - 1));
+  }
+
+  Future<void> playLocal(
+    List<LocalLibraryItem> items, {
+    int initialIndex = 0,
+  }) async {
+    final media = items
+        .where((i) => i.filePath.trim().isNotEmpty)
+        .map(playableFromLocal)
+        .toList();
+    if (media.isEmpty) return;
+    await playAll(media, initialIndex: initialIndex.clamp(0, media.length - 1));
+  }
+
+  Future<void> play() async => _handler?.play();
+  Future<void> pause() async => _handler?.pause();
+  Future<void> stop() async => _handler?.stop();
+  Future<void> seek(Duration position) async => _handler?.seek(position);
+  Future<void> next() async => _handler?.skipToNext();
+  Future<void> previous() async => _handler?.skipToPrevious();
+
+  Future<void> togglePlayPause(bool isPlaying) async {
+    if (isPlaying) {
+      await pause();
+    } else {
+      await play();
+    }
+  }
+
+  Future<void> setShuffle(bool enabled) async {
+    await _handler?.setShuffleMode(
+      enabled ? AudioServiceShuffleMode.all : AudioServiceShuffleMode.none,
+    );
+  }
+
+  Future<void> playNext(PlayableMedia item) async =>
+      (await ensureInitialized())?.enqueue(item, playNext: true);
+
+  Future<void> addToQueue(PlayableMedia item) async =>
+      (await ensureInitialized())?.enqueue(item);
+
+  Future<void> playNextHistory(DownloadHistoryItem item) async =>
+      playNext(playableFromHistory(item));
+
+  Future<void> addToQueueHistory(DownloadHistoryItem item) async =>
+      addToQueue(playableFromHistory(item));
+
+  Future<void> playNextLocal(LocalLibraryItem item) async =>
+      playNext(playableFromLocal(item));
+
+  Future<void> addToQueueLocal(LocalLibraryItem item) async =>
+      addToQueue(playableFromLocal(item));
+
+  Future<void> jumpTo(int index) async => _handler?.skipToQueueItem(index);
+
+  void moveQueueItem(int oldIndex, int newIndex) {
+    _handler?.moveQueueItem(oldIndex, newIndex);
+  }
+}
+
+final musicPlayerControllerProvider = Provider<MusicPlayerController>(
+  (ref) => const MusicPlayerController(),
+);
+
+PlayableMedia playableFromHistory(DownloadHistoryItem item) {
+  return PlayableMedia(
+    id: item.id,
+    source: item.filePath,
+    title: item.trackName,
+    artist: item.artistName,
+    album: item.albumName,
+    artUri: (item.coverUrl != null && item.coverUrl!.trim().isNotEmpty)
+        ? item.coverUrl
+        : null,
+    duration: (item.duration != null && item.duration! > 0)
+        ? Duration(seconds: item.duration!)
+        : null,
+  );
+}
+
+PlayableMedia playableFromLocal(LocalLibraryItem item) {
+  String? art;
+  final cover = item.coverPath;
+  if (cover != null && cover.trim().isNotEmpty) {
+    art = cover.startsWith('http') || cover.startsWith('content://')
+        ? cover
+        : Uri.file(cover).toString();
+  }
+  return PlayableMedia(
+    id: item.id,
+    source: item.filePath,
+    title: item.trackName,
+    artist: item.artistName,
+    album: item.albumName,
+    artUri: art,
+    duration: (item.duration != null && item.duration! > 0)
+        ? Duration(seconds: item.duration!)
+        : null,
+  );
+}

lib/providers/playback_provider.dart

@@ -2,7 +2,10 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:spotiflac_android/models/track.dart';
 import 'package:spotiflac_android/providers/download_queue_provider.dart';
 import 'package:spotiflac_android/providers/local_library_provider.dart';
+import 'package:spotiflac_android/providers/music_player_provider.dart';
+import 'package:spotiflac_android/providers/settings_provider.dart';
 import 'package:spotiflac_android/services/library_database.dart';
+import 'package:spotiflac_android/services/music_player_service.dart';
 import 'package:spotiflac_android/utils/file_access.dart';
 import 'package:spotiflac_android/utils/logger.dart';
 
@@ -16,6 +19,24 @@ class PlaybackController extends Notifier<PlaybackState> {
   @override
   PlaybackState build() => const PlaybackState();
 
+  Future<bool> _useInternalPlayer() async {
+    final mode = ref.read(settingsProvider).playerMode;
+    if (mode != 'internal') return false;
+    return await ref.read(musicPlayerControllerProvider).ensureInitialized() !=
+        null;
+  }
+
+  String? _normalizeArtUri(String cover) {
+    final value = cover.trim();
+    if (value.isEmpty) return null;
+    if (value.startsWith('http') ||
+        value.startsWith('content://') ||
+        value.startsWith('file://')) {
+      return value;
+    }
+    return Uri.file(value).toString();
+  }
+
   Future<void> playLocalPath({
     required String path,
     required String title,
@@ -27,14 +48,143 @@ class PlaybackController extends Notifier<PlaybackState> {
     if (isCueVirtualPath(path)) {
       throw Exception(cueVirtualTrackRequiresSplitMessage);
     }
+
+    if (await _useInternalPlayer()) {
+      _log.d('Playing "$title" in the internal player: $path');
+      await ref
+          .read(musicPlayerControllerProvider)
+          .playSingle(
+            PlayableMedia(
+              id: path,
+              source: path,
+              title: title,
+              artist: artist,
+              album: album,
+              artUri: _normalizeArtUri(coverUrl),
+              duration: (track != null && track.duration > 0)
+                  ? Duration(seconds: track.duration)
+                  : null,
+            ),
+          );
+      return;
+    }
+
     _log.d('Opening external player for "$title" by $artist: $path');
     await openFile(path);
   }
 
+  /// Plays a local-library album/list starting at [startItem], queuing the rest
+  /// so playback continues to the next track automatically. Honors player mode.
+  Future<void> playLocalLibraryQueue(
+    List<LocalLibraryItem> items, {
+    required LocalLibraryItem startItem,
+  }) async {
+    final playable = items
+        .where(
+          (i) => i.filePath.trim().isNotEmpty && !isCueVirtualPath(i.filePath),
+        )
+        .toList();
+    if (playable.isEmpty) return;
+    var startIndex = playable.indexWhere((i) => i.id == startItem.id);
+    if (startIndex < 0) startIndex = 0;
+
+    if (await _useInternalPlayer()) {
+      await ref
+          .read(musicPlayerControllerProvider)
+          .playLocal(playable, initialIndex: startIndex);
+    } else {
+      await openFile(playable[startIndex].filePath);
+    }
+  }
+
+  /// Plays a downloaded-history album/list starting at [startItem], queuing the
+  /// rest. Honors player mode.
+  Future<void> playHistoryQueue(
+    List<DownloadHistoryItem> items, {
+    required DownloadHistoryItem startItem,
+  }) async {
+    final playable = items
+        .where(
+          (i) => i.filePath.trim().isNotEmpty && !isCueVirtualPath(i.filePath),
+        )
+        .toList();
+    if (playable.isEmpty) return;
+    var startIndex = playable.indexWhere((i) => i.id == startItem.id);
+    if (startIndex < 0) startIndex = 0;
+
+    if (await _useInternalPlayer()) {
+      await ref
+          .read(musicPlayerControllerProvider)
+          .playHistory(playable, initialIndex: startIndex);
+    } else {
+      await openFile(playable[startIndex].filePath);
+    }
+  }
+
+  /// Plays a prebuilt media queue starting at [startIndex]. Honors player mode
+  /// ([externalPath] is opened externally when the built-in player is off).
+  Future<void> playMediaQueue(
+    Iterable<PlayableMedia> queue, {
+    required int startIndex,
+    required String externalPath,
+  }) async {
+    if (await _useInternalPlayer()) {
+      final items = queue.toList(growable: false);
+      if (items.isEmpty) return;
+      final i = startIndex.clamp(0, items.length - 1);
+      await ref
+          .read(musicPlayerControllerProvider)
+          .playAll(items, initialIndex: i);
+    } else {
+      await openFile(externalPath);
+    }
+  }
+
   Future<void> playTrackList(List<Track> tracks, {int startIndex = 0}) async {
     if (tracks.isEmpty) return;
 
     final orderedTracks = _orderedTracksFromStartIndex(tracks, startIndex);
+
+    if (await _useInternalPlayer()) {
+      final queue = <PlayableMedia>[];
+      var skippedCueVirtualTrack = false;
+      final resolvedPaths = await _resolveTrackPaths(orderedTracks);
+      for (var index = 0; index < orderedTracks.length; index++) {
+        final track = orderedTracks[index];
+        final resolvedPath = resolvedPaths[index];
+        if (resolvedPath == null) continue;
+        if (isCueVirtualPath(resolvedPath)) {
+          skippedCueVirtualTrack = true;
+          continue;
+        }
+        queue.add(
+          PlayableMedia(
+            id: resolvedPath,
+            source: resolvedPath,
+            title: track.name,
+            artist: track.artistName,
+            album: track.albumName,
+            artUri: _normalizeArtUri(track.coverUrl ?? ''),
+            duration: track.duration > 0
+                ? Duration(seconds: track.duration)
+                : null,
+          ),
+        );
+      }
+
+      if (queue.isNotEmpty) {
+        _log.d('Playing ${queue.length} tracks in the internal player');
+        await ref.read(musicPlayerControllerProvider).playAll(queue);
+        return;
+      }
+      if (skippedCueVirtualTrack) {
+        throw Exception(cueVirtualTrackRequiresSplitMessage);
+      }
+      throw Exception(
+        'No local audio file is available to play. Download the track first.',
+      );
+    }
+
     var skippedCueVirtualTrack = false;
     for (final track in orderedTracks) {
       final resolvedPath = await _resolveTrackPath(track);
@@ -98,6 +248,23 @@ class PlaybackController extends Notifier<PlaybackState> {
     return null;
   }
 
+  Future<List<String?>> _resolveTrackPaths(List<Track> tracks) async {
+    if (tracks.isEmpty) return const [];
+    final results = List<String?>.filled(tracks.length, null);
+    var next = 0;
+    final workerCount = tracks.length < 4 ? tracks.length : 4;
+    Future<void> worker() async {
+      while (true) {
+        final index = next++;
+        if (index >= tracks.length) return;
+        results[index] = await _resolveTrackPath(tracks[index]);
+      }
+    }
+
+    await Future.wait(List.generate(workerCount, (_) => worker()));
+    return results;
+  }
+
   Future<LocalLibraryItem?> _findLocalLibraryItemForTrack(Track track) async {
     final isLocalSource = (track.source ?? '').toLowerCase() == 'local';
     if (isLocalSource) {