chore: bump app to v4.2.2

.github/workflows/release.yml

@@ -164,13 +164,18 @@ jobs:
           path: build/app/outputs/flutter-apk/SpotiFLAC-*.apk
 
   build-ios:
-    runs-on: macos-latest
+    runs-on: macos-15
     needs: get-version # Only depends on version, NOT android build!
 
     steps:
       - name: Checkout repository
         uses: actions/checkout@v6
 
+      - name: Select Xcode 26.1.1
+        run: |
+          sudo xcode-select -s /Applications/Xcode_26.1.1.app
+          xcodebuild -version
+
       - name: Setup Go
         uses: actions/setup-go@v6
         with:

android/app/build.gradle.kts

@@ -57,6 +57,18 @@ android {
     }
 
     buildTypes {
+        getByName("debug") {
+            ndk {
+                debugSymbolLevel = "FULL"
+            }
+        }
+
+        getByName("profile") {
+            ndk {
+                debugSymbolLevel = "FULL"
+            }
+        }
+
         release {
             // For local builds: use release signing if key.properties exists
             // For CI builds: APK is signed by GitHub Action after build
@@ -71,6 +83,9 @@ android {
                 getDefaultProguardFile("proguard-android-optimize.txt"),
                 "proguard-rules.pro"
             )
+            ndk {
+                debugSymbolLevel = "FULL"
+            }
         }
     }
     

android/app/src/main/AndroidManifest.xml

@@ -94,24 +94,6 @@
             android:exported="false"
             android:foregroundServiceType="dataSync" />
 
-        <!-- Audio playback service for media notification / background audio -->
-        <service
-            android:name="com.ryanheise.audioservice.AudioService"
-            android:exported="true"
-            android:foregroundServiceType="mediaPlayback">
-            <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">

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

@@ -944,16 +944,19 @@ class MainActivity: FlutterFragmentActivity() {
                 ) {
                     try {
                         val srcFile = java.io.File(goFilePath)
-                        if (srcFile.exists() && srcFile.length() > 0) {
-                            contentResolver.openOutputStream(document.uri, "wt")?.use { output ->
-                                srcFile.inputStream().use { input ->
-                                    input.copyTo(output)
-                                }
-                            }
-                            srcFile.delete()
+                        if (!srcFile.exists() || srcFile.length() <= 0) {
+                            throw IllegalStateException("extension output missing or empty: $goFilePath")
                         }
+                        contentResolver.openOutputStream(document.uri, "wt")?.use { output ->
+                            srcFile.inputStream().use { input ->
+                                input.copyTo(output)
+                            }
+                        } ?: throw IllegalStateException("failed to open SAF output stream")
+                        srcFile.delete()
                     } catch (e: Exception) {
+                        document.delete()
                         android.util.Log.w("SpotiFLAC", "Failed to copy extension output to SAF: ${e.message}")
+                        return errorJson("Failed to copy extension output to SAF: ${e.message}")
                     }
                 }
                 respObj.put("file_path", document.uri.toString())
@@ -2965,6 +2968,13 @@ class MainActivity: FlutterFragmentActivity() {
                             }
                             result.success(response)
                         }
+                        "setDownloadFallbackExtensionIds" -> {
+                            val extensionIdsJson = call.argument<String>("extension_ids") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setExtensionFallbackProviderIDsJSON(extensionIdsJson)
+                            }
+                            result.success(null)
+                        }
                         "setMetadataProviderPriority" -> {
                             val priorityJson = call.argument<String>("priority") ?: "[]"
                             withContext(Dispatchers.IO) {

go_backend/ape_tags.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"io"
 	"os"
-	"strconv"
 	"strings"
 )
 
@@ -367,12 +366,9 @@ func APETagToAudioMetadata(tag *APETag) *AudioMetadata {
 		case "DATE":
 			metadata.Date = value
 		case "TRACK", "TRACKNUMBER":
-			// APE track format can be "3" or "3/12"
-			trackNum, _ := strconv.Atoi(strings.Split(value, "/")[0])
-			metadata.TrackNumber = trackNum
+			metadata.TrackNumber, metadata.TotalTracks = parseIndexPair(value)
 		case "DISC", "DISCNUMBER":
-			discNum, _ := strconv.Atoi(strings.Split(value, "/")[0])
-			metadata.DiscNumber = discNum
+			metadata.DiscNumber, metadata.TotalDiscs = parseIndexPair(value)
 		case "ISRC":
 			metadata.ISRC = value
 		case "LYRICS", "UNSYNCEDLYRICS":
@@ -425,10 +421,10 @@ func AudioMetadataToAPEItems(metadata *AudioMetadata) []APETagItem {
 		addItem("Year", metadata.Year)
 	}
 	if metadata.TrackNumber > 0 {
-		addItem("Track", strconv.Itoa(metadata.TrackNumber))
+		addItem("Track", formatIndexValue(metadata.TrackNumber, metadata.TotalTracks))
 	}
 	if metadata.DiscNumber > 0 {
-		addItem("Disc", strconv.Itoa(metadata.DiscNumber))
+		addItem("Disc", formatIndexValue(metadata.DiscNumber, metadata.TotalDiscs))
 	}
 	addItem("ISRC", metadata.ISRC)
 	addItem("Lyrics", metadata.Lyrics)
@@ -453,7 +449,7 @@ func apeKeysFromFields(fields map[string]string) map[string]struct{} {
 		"artist":                "ARTIST",
 		"album":                 "ALBUM",
 		"album_artist":          "ALBUM ARTIST",
-		"date":                  "YEAR",
+		"date":                  "DATE",
 		"genre":                 "GENRE",
 		"track_number":          "TRACK",
 		"disc_number":           "DISC",
@@ -475,7 +471,7 @@ func apeKeysFromFields(fields map[string]string) map[string]struct{} {
 		}
 	}
 	// Some fields have reader aliases that must also be cleared when the
-	// canonical key is updated (e.g. "Year" writer ↔ DATE/YEAR reader,
+	// canonical key is updated (e.g. DATE writer ↔ DATE/YEAR reader,
 	// DISC ↔ DISCNUMBER, TRACK ↔ TRACKNUMBER, "ALBUM ARTIST" ↔ ALBUMARTIST,
 	// LABEL ↔ PUBLISHER, LYRICS ↔ UNSYNCEDLYRICS).
 	if _, present := fields["date"]; present {
@@ -484,9 +480,15 @@ func apeKeysFromFields(fields map[string]string) map[string]struct{} {
 	if _, present := fields["disc_number"]; present {
 		result["DISCNUMBER"] = struct{}{}
 	}
+	if _, present := fields["disc_total"]; present {
+		result["DISCNUMBER"] = struct{}{}
+	}
 	if _, present := fields["track_number"]; present {
 		result["TRACKNUMBER"] = struct{}{}
 	}
+	if _, present := fields["track_total"]; present {
+		result["TRACKNUMBER"] = struct{}{}
+	}
 	if _, present := fields["album_artist"]; present {
 		result["ALBUMARTIST"] = struct{}{}
 	}

go_backend/audio_metadata.go

@@ -21,7 +21,9 @@ type AudioMetadata struct {
 	Year        string
 	Date        string
 	TrackNumber int
+	TotalTracks int
 	DiscNumber  int
+	TotalDiscs  int
 	ISRC        string
 	Lyrics      string
 	Label       string
@@ -173,9 +175,9 @@ func parseID3v22Frames(data []byte, metadata *AudioMetadata, tagUnsync bool) {
 		case "TCO":
 			metadata.Genre = cleanGenre(value)
 		case "TRK":
-			metadata.TrackNumber = parseTrackNumber(value)
+			metadata.TrackNumber, metadata.TotalTracks = parseIndexPair(value)
 		case "TPA":
-			metadata.DiscNumber = parseTrackNumber(value)
+			metadata.DiscNumber, metadata.TotalDiscs = parseIndexPair(value)
 		case "TCM":
 			metadata.Composer = value
 		case "TPB":
@@ -292,9 +294,9 @@ func parseID3v23Frames(data []byte, metadata *AudioMetadata, version byte, tagUn
 		case "TCON":
 			metadata.Genre = cleanGenre(value)
 		case "TRCK":
-			metadata.TrackNumber = parseTrackNumber(value)
+			metadata.TrackNumber, metadata.TotalTracks = parseIndexPair(value)
 		case "TPOS":
-			metadata.DiscNumber = parseTrackNumber(value)
+			metadata.DiscNumber, metadata.TotalDiscs = parseIndexPair(value)
 		case "TSRC":
 			metadata.ISRC = value
 		case "TCOM":
@@ -580,14 +582,28 @@ func cleanGenre(genre string) string {
 }
 
 func parseTrackNumber(s string) int {
-	s = strings.TrimSpace(s)
-	if idx := strings.Index(s, "/"); idx > 0 {
-		s = s[:idx]
-	}
-	num, _ := strconv.Atoi(s)
+	num, _ := parseIndexPair(s)
 	return num
 }
 
+func parseIndexPair(s string) (int, int) {
+	s = strings.TrimSpace(s)
+	if s == "" {
+		return 0, 0
+	}
+
+	first := s
+	second := ""
+	if idx := strings.Index(s, "/"); idx > 0 {
+		first = s[:idx]
+		second = s[idx+1:]
+	}
+
+	num, _ := strconv.Atoi(strings.TrimSpace(first))
+	total, _ := strconv.Atoi(strings.TrimSpace(second))
+	return num, total
+}
+
 func removeUnsync(data []byte) []byte {
 	if len(data) == 0 {
 		return data
@@ -1037,9 +1053,9 @@ func parseVorbisComments(data []byte, metadata *AudioMetadata) {
 		case "GENRE":
 			metadata.Genre = value
 		case "TRACKNUMBER", "TRACK":
-			metadata.TrackNumber = parseTrackNumber(value)
+			metadata.TrackNumber, metadata.TotalTracks = parseIndexPair(value)
 		case "DISCNUMBER", "DISC":
-			metadata.DiscNumber = parseTrackNumber(value)
+			metadata.DiscNumber, metadata.TotalDiscs = parseIndexPair(value)
 		case "ISRC":
 			metadata.ISRC = value
 		case "COMPOSER":

go_backend/cue_parser.go

@@ -513,6 +513,11 @@ func scanCueSheetForLibrary(cuePath string, sheet *CueSheet, audioPath, virtualP
 			album = "Unknown Album"
 		}
 
+		composer := track.Composer
+		if composer == "" {
+			composer = sheet.Composer
+		}
+
 		var duration int
 		if i+1 < len(sheet.Tracks) {
 			nextStart := sheet.Tracks[i+1].StartTime
@@ -539,12 +544,15 @@ func scanCueSheetForLibrary(cuePath string, sheet *CueSheet, audioPath, virtualP
 			ScannedAt:   scanTime,
 			ISRC:        track.ISRC,
 			TrackNumber: track.Number,
+			TotalTracks: len(sheet.Tracks),
 			DiscNumber:  1,
+			TotalDiscs:  1,
 			Duration:    duration,
 			ReleaseDate: sheet.Date,
 			BitDepth:    bitDepth,
 			SampleRate:  sampleRate,
 			Genre:       sheet.Genre,
+			Composer:    composer,
 			Format:      "cue+" + strings.TrimPrefix(audioExt, "."),
 		}
 

go_backend/deezer.go

@@ -630,6 +630,12 @@ func (c *DeezerClient) GetAlbum(ctx context.Context, albumID string) (*AlbumResp
 	}
 
 	isrcMap := c.fetchISRCsParallel(ctx, allTracks)
+	totalDiscs := 0
+	for _, track := range allTracks {
+		if track.DiskNumber > totalDiscs {
+			totalDiscs = track.DiskNumber
+		}
+	}
 
 	tracks := make([]AlbumTrackMetadata, 0, len(allTracks))
 	albumType := album.RecordType
@@ -658,6 +664,7 @@ func (c *DeezerClient) GetAlbum(ctx context.Context, albumID string) (*AlbumResp
 			TrackNumber: trackNum,
 			TotalTracks: album.NbTracks,
 			DiscNumber:  track.DiskNumber,
+			TotalDiscs:  totalDiscs,
 			ExternalURL: track.Link,
 			ISRC:        isrc,
 			AlbumID:     fmt.Sprintf("deezer:%d", album.ID),

go_backend/deezer_download.go

@@ -1,444 +0,0 @@
-package gobackend
-
-import (
-	"bufio"
-	"bytes"
-	"context"
-	"encoding/json"
-	"errors"
-	"fmt"
-	"io"
-	"net/http"
-	"os"
-	"path/filepath"
-	"strings"
-)
-
-const deezerMusicDLURL = "https://api.zarz.moe/v1/dzr"
-
-type DeezerDownloadResult struct {
-	FilePath    string
-	BitDepth    int
-	SampleRate  int
-	Title       string
-	Artist      string
-	Album       string
-	ReleaseDate string
-	TrackNumber int
-	DiscNumber  int
-	ISRC        string
-	LyricsLRC   string
-}
-
-func isLikelySpotifyTrackID(value string) bool {
-	if len(value) != 22 {
-		return false
-	}
-	for _, r := range value {
-		switch {
-		case r >= 'A' && r <= 'Z':
-		case r >= 'a' && r <= 'z':
-		case r >= '0' && r <= '9':
-		default:
-			return false
-		}
-	}
-	return true
-}
-
-func resolveDeezerTrackURL(req DownloadRequest) (string, error) {
-	deezerID := strings.TrimSpace(req.DeezerID)
-	if deezerID == "" {
-		if prefixed, found := strings.CutPrefix(strings.TrimSpace(req.SpotifyID), "deezer:"); found {
-			deezerID = strings.TrimSpace(prefixed)
-		}
-	}
-	if deezerID != "" {
-		trackURL := fmt.Sprintf("https://www.deezer.com/track/%s", deezerID)
-		if err := verifyDeezerTrack(req, deezerID, false); err != nil {
-			GoLog("[Deezer] Direct ID %s verification failed: %v\n", deezerID, err)
-			// Don't reject direct IDs from request payload — they're presumably correct.
-		}
-		return trackURL, nil
-	}
-
-	spotifyID := strings.TrimSpace(req.SpotifyID)
-	if spotifyID != "" && isLikelySpotifyTrackID(spotifyID) {
-		songlink := NewSongLinkClient()
-		availability, err := songlink.CheckTrackAvailability(spotifyID, "")
-		if err == nil && availability.Deezer && availability.DeezerURL != "" {
-			resolvedID := extractDeezerIDFromURL(availability.DeezerURL)
-			if resolvedID != "" {
-				if verifyErr := verifyDeezerTrack(req, resolvedID, true); verifyErr != nil {
-					GoLog("[Deezer] SongLink ID %s rejected: %v\n", resolvedID, verifyErr)
-					// Fall through to ISRC search instead of using wrong track.
-				} else {
-					return availability.DeezerURL, nil
-				}
-			} else {
-				return availability.DeezerURL, nil
-			}
-		}
-	}
-
-	isrc := strings.TrimSpace(req.ISRC)
-	if isrc != "" {
-		ctx, cancel := context.WithTimeout(context.Background(), SongLinkTimeout)
-		defer cancel()
-		track, err := GetDeezerClient().SearchByISRC(ctx, isrc)
-		if err == nil && track != nil {
-			resolvedID := songLinkExtractDeezerTrackID(track)
-			if resolvedID != "" {
-				if verifyErr := verifyDeezerTrack(req, resolvedID, false); verifyErr != nil {
-					GoLog("[Deezer] ISRC-resolved ID %s rejected: %v\n", resolvedID, verifyErr)
-					return "", fmt.Errorf("deezer track resolved via ISRC does not match: %w", verifyErr)
-				}
-				return fmt.Sprintf("https://www.deezer.com/track/%s", resolvedID), nil
-			}
-		}
-	}
-
-	return "", fmt.Errorf("could not resolve Deezer track URL")
-}
-
-func verifyDeezerTrack(req DownloadRequest, deezerID string, skipNameVerification bool) error {
-	ctx, cancel := context.WithTimeout(context.Background(), SongLinkTimeout)
-	defer cancel()
-	trackResp, err := GetDeezerClient().GetTrack(ctx, deezerID)
-	if err != nil {
-		return nil // Can't verify — don't block the download.
-	}
-	resolved := resolvedTrackInfo{
-		Title:                trackResp.Track.Name,
-		ArtistName:           trackResp.Track.Artists,
-		ISRC:                 trackResp.Track.ISRC,
-		Duration:             trackResp.Track.DurationMS / 1000,
-		SkipNameVerification: skipNameVerification,
-	}
-	if !trackMatchesRequest(req, resolved, "Deezer") {
-		return fmt.Errorf("expected '%s - %s', got '%s - %s'",
-			req.ArtistName, req.TrackName, resolved.ArtistName, resolved.Title)
-	}
-	GoLog("[Deezer] Track %s verified: '%s - %s' ✓\n", deezerID, resolved.ArtistName, resolved.Title)
-	return nil
-}
-
-type deezerMusicDLRequest struct {
-	Platform string `json:"platform"`
-	URL      string `json:"url"`
-}
-
-func (c *DeezerClient) GetMusicDLDownloadURL(deezerTrackURL string) (string, error) {
-	payload := deezerMusicDLRequest{
-		Platform: "deezer",
-		URL:      deezerTrackURL,
-	}
-	jsonData, err := json.Marshal(payload)
-	if err != nil {
-		return "", fmt.Errorf("failed to encode MusicDL request: %w", err)
-	}
-
-	req, err := http.NewRequest(http.MethodPost, deezerMusicDLURL, bytes.NewReader(jsonData))
-	if err != nil {
-		return "", fmt.Errorf("failed to create MusicDL request: %w", err)
-	}
-	req.Header.Set("Content-Type", "application/json")
-	req.Header.Set("User-Agent", getRandomUserAgent())
-
-	resp, err := c.httpClient.Do(req)
-	if err != nil {
-		return "", fmt.Errorf("MusicDL request failed: %w", err)
-	}
-	defer resp.Body.Close()
-
-	body, err := io.ReadAll(io.LimitReader(resp.Body, 64*1024))
-	if err != nil {
-		return "", fmt.Errorf("failed to read MusicDL response: %w", err)
-	}
-
-	if resp.StatusCode != http.StatusOK {
-		return "", fmt.Errorf("MusicDL returned HTTP %d: %s", resp.StatusCode, strings.TrimSpace(string(body)))
-	}
-
-	var raw map[string]any
-	if err := json.Unmarshal(body, &raw); err != nil {
-		return "", fmt.Errorf("invalid MusicDL JSON: %w", err)
-	}
-
-	if errMsg, ok := raw["error"].(string); ok && strings.TrimSpace(errMsg) != "" {
-		return "", fmt.Errorf("MusicDL error: %s", errMsg)
-	}
-
-	for _, key := range []string{"download_url", "url", "link"} {
-		if urlVal, ok := raw[key].(string); ok && strings.TrimSpace(urlVal) != "" {
-			return strings.TrimSpace(urlVal), nil
-		}
-	}
-	if data, ok := raw["data"].(map[string]any); ok {
-		for _, key := range []string{"download_url", "url", "link"} {
-			if urlVal, ok := data[key].(string); ok && strings.TrimSpace(urlVal) != "" {
-				return strings.TrimSpace(urlVal), nil
-			}
-		}
-	}
-
-	return "", fmt.Errorf("no download URL found in MusicDL response")
-}
-
-func (c *DeezerClient) DownloadFromMusicDL(deezerTrackURL, outputPath string, outputFD int, itemID string) error {
-	GoLog("[Deezer] Resolving download URL via MusicDL for: %s\n", deezerTrackURL)
-
-	downloadURL, err := c.GetMusicDLDownloadURL(deezerTrackURL)
-	if err != nil {
-		return err
-	}
-	GoLog("[Deezer] MusicDL returned download URL, starting download...\n")
-
-	ctx := context.Background()
-	if itemID != "" {
-		StartItemProgress(itemID)
-		defer CompleteItemProgress(itemID)
-		ctx = initDownloadCancel(itemID)
-		defer clearDownloadCancel(itemID)
-	}
-
-	if isDownloadCancelled(itemID) {
-		return ErrDownloadCancelled
-	}
-
-	req, err := http.NewRequestWithContext(ctx, "GET", downloadURL, nil)
-	if err != nil {
-		return fmt.Errorf("failed to create download request: %w", err)
-	}
-	req.Header.Set("User-Agent", getRandomUserAgent())
-
-	resp, err := GetDownloadClient().Do(req)
-	if err != nil {
-		if isDownloadCancelled(itemID) {
-			return ErrDownloadCancelled
-		}
-		return fmt.Errorf("download request failed: %w", err)
-	}
-	defer resp.Body.Close()
-
-	if resp.StatusCode != http.StatusOK {
-		return fmt.Errorf("download returned HTTP %d", resp.StatusCode)
-	}
-
-	expectedSize := resp.ContentLength
-	if expectedSize > 0 && itemID != "" {
-		SetItemBytesTotal(itemID, expectedSize)
-	}
-
-	out, err := openOutputForWrite(outputPath, outputFD)
-	if err != nil {
-		return err
-	}
-
-	bufWriter := bufio.NewWriterSize(out, 256*1024)
-	var written int64
-	if itemID != "" {
-		pw := NewItemProgressWriter(bufWriter, itemID)
-		written, err = io.Copy(pw, resp.Body)
-	} else {
-		written, err = io.Copy(bufWriter, resp.Body)
-	}
-
-	flushErr := bufWriter.Flush()
-	closeErr := out.Close()
-
-	if err != nil {
-		cleanupOutputOnError(outputPath, outputFD)
-		if isDownloadCancelled(itemID) {
-			return ErrDownloadCancelled
-		}
-		return fmt.Errorf("download interrupted: %w", err)
-	}
-	if flushErr != nil {
-		cleanupOutputOnError(outputPath, outputFD)
-		return fmt.Errorf("failed to flush output: %w", flushErr)
-	}
-	if closeErr != nil {
-		cleanupOutputOnError(outputPath, outputFD)
-		return fmt.Errorf("failed to close output: %w", closeErr)
-	}
-
-	if expectedSize > 0 && written != expectedSize {
-		cleanupOutputOnError(outputPath, outputFD)
-		return fmt.Errorf("incomplete download: expected %d bytes, got %d bytes", expectedSize, written)
-	}
-
-	GoLog("[Deezer] Downloaded via MusicDL: %.2f MB\n", float64(written)/(1024*1024))
-	return nil
-}
-
-func downloadFromDeezer(req DownloadRequest) (DeezerDownloadResult, error) {
-	deezerClient := GetDeezerClient()
-	isSafOutput := isFDOutput(req.OutputFD) || strings.TrimSpace(req.OutputPath) != ""
-
-	if !isSafOutput {
-		if existingFile, exists := checkISRCExistsInternal(req.OutputDir, req.ISRC); exists {
-			return DeezerDownloadResult{FilePath: "EXISTS:" + existingFile}, nil
-		}
-	}
-
-	filename := buildFilenameFromTemplate(req.FilenameFormat, map[string]interface{}{
-		"title":  req.TrackName,
-		"artist": req.ArtistName,
-		"album":  req.AlbumName,
-		"track":  req.TrackNumber,
-		"year":   extractYear(req.ReleaseDate),
-		"date":   req.ReleaseDate,
-		"disc":   req.DiscNumber,
-	})
-
-	var outputPath string
-	if isSafOutput {
-		outputPath = strings.TrimSpace(req.OutputPath)
-		if outputPath == "" && isFDOutput(req.OutputFD) {
-			outputPath = fmt.Sprintf("/proc/self/fd/%d", req.OutputFD)
-		}
-	} else {
-		filename = sanitizeFilename(filename) + ".flac"
-		outputPath = filepath.Join(req.OutputDir, filename)
-		if fileInfo, statErr := os.Stat(outputPath); statErr == nil && fileInfo.Size() > 0 {
-			return DeezerDownloadResult{FilePath: "EXISTS:" + outputPath}, nil
-		}
-	}
-
-	var parallelResult *ParallelDownloadResult
-	parallelDone := make(chan struct{})
-	go func() {
-		defer close(parallelDone)
-		coverURL := req.CoverURL
-		embedLyrics := req.EmbedLyrics
-		if !req.EmbedMetadata {
-			coverURL = ""
-			embedLyrics = false
-		}
-		parallelResult = FetchCoverAndLyricsParallel(
-			coverURL,
-			req.EmbedMaxQualityCover,
-			req.SpotifyID,
-			req.TrackName,
-			req.ArtistName,
-			embedLyrics,
-			int64(req.DurationMS),
-		)
-	}()
-
-	deezerTrackURL, deezerURLErr := resolveDeezerTrackURL(req)
-	if deezerURLErr != nil {
-		return DeezerDownloadResult{}, fmt.Errorf(
-			"deezer download failed: could not resolve Deezer URL: %w",
-			deezerURLErr,
-		)
-	}
-
-	GoLog("[Deezer] Trying MusicDL for: %s\n", deezerTrackURL)
-	downloadErr := deezerClient.DownloadFromMusicDL(
-		deezerTrackURL,
-		outputPath,
-		req.OutputFD,
-		req.ItemID,
-	)
-	if downloadErr != nil {
-		if errors.Is(downloadErr, ErrDownloadCancelled) {
-			return DeezerDownloadResult{}, ErrDownloadCancelled
-		}
-		return DeezerDownloadResult{}, fmt.Errorf(
-			"deezer download failed via MusicDL: %w",
-			downloadErr,
-		)
-	}
-
-	<-parallelDone
-
-	if req.ItemID != "" {
-		SetItemProgress(req.ItemID, 1.0, 0, 0)
-		SetItemFinalizing(req.ItemID)
-	}
-
-	metadata := Metadata{
-		Title:         req.TrackName,
-		Artist:        req.ArtistName,
-		Album:         req.AlbumName,
-		AlbumArtist:   req.AlbumArtist,
-		ArtistTagMode: req.ArtistTagMode,
-		Date:          req.ReleaseDate,
-		TrackNumber:   req.TrackNumber,
-		TotalTracks:   req.TotalTracks,
-		DiscNumber:    req.DiscNumber,
-		ISRC:          req.ISRC,
-		Genre:         req.Genre,
-		Label:         req.Label,
-		Copyright:     req.Copyright,
-	}
-
-	var coverData []byte
-	if parallelResult != nil && parallelResult.CoverData != nil {
-		coverData = parallelResult.CoverData
-	}
-
-	if isSafOutput || !req.EmbedMetadata {
-		if !req.EmbedMetadata {
-			GoLog("[Deezer] Metadata embedding disabled by settings, skipping in-backend metadata/lyrics embedding\n")
-		} else {
-			GoLog("[Deezer] SAF output detected - skipping in-backend metadata/lyrics embedding (handled in Flutter)\n")
-		}
-	} else {
-		if err := EmbedMetadataWithCoverData(outputPath, metadata, coverData); err != nil {
-			GoLog("[Deezer] Warning: failed to embed metadata: %v\n", err)
-		}
-
-		if req.EmbedLyrics && parallelResult != nil && parallelResult.LyricsLRC != "" {
-			lyricsMode := req.LyricsMode
-			if lyricsMode == "" {
-				lyricsMode = "embed"
-			}
-
-			if lyricsMode == "external" || lyricsMode == "both" {
-				if lrcPath, lrcErr := SaveLRCFile(outputPath, parallelResult.LyricsLRC); lrcErr != nil {
-					GoLog("[Deezer] Warning: failed to save LRC file: %v\n", lrcErr)
-				} else {
-					GoLog("[Deezer] LRC file saved: %s\n", lrcPath)
-				}
-			}
-
-			if lyricsMode == "embed" || lyricsMode == "both" {
-				if embedErr := EmbedLyrics(outputPath, parallelResult.LyricsLRC); embedErr != nil {
-					GoLog("[Deezer] Warning: failed to embed lyrics: %v\n", embedErr)
-				}
-			}
-		}
-	}
-
-	if !isSafOutput {
-		AddToISRCIndex(req.OutputDir, req.ISRC, outputPath)
-	}
-
-	bitDepth, sampleRate := 0, 0
-	if quality, qErr := GetAudioQuality(outputPath); qErr == nil {
-		bitDepth = quality.BitDepth
-		sampleRate = quality.SampleRate
-	}
-
-	lyricsLRC := ""
-	if req.EmbedMetadata && req.EmbedLyrics && parallelResult != nil && parallelResult.LyricsLRC != "" {
-		lyricsLRC = parallelResult.LyricsLRC
-	}
-
-	return DeezerDownloadResult{
-		FilePath:    outputPath,
-		BitDepth:    bitDepth,
-		SampleRate:  sampleRate,
-		Title:       req.TrackName,
-		Artist:      req.ArtistName,
-		Album:       req.AlbumName,
-		ReleaseDate: req.ReleaseDate,
-		TrackNumber: req.TrackNumber,
-		DiscNumber:  req.DiscNumber,
-		ISRC:        req.ISRC,
-		LyricsLRC:   lyricsLRC,
-	}, nil
-}

go_backend/exports.go

@@ -55,6 +55,7 @@ type DownloadRequest struct {
 	TrackNumber          int    `json:"track_number"`
 	DiscNumber           int    `json:"disc_number"`
 	TotalTracks          int    `json:"total_tracks"`
+	TotalDiscs           int    `json:"total_discs,omitempty"`
 	ReleaseDate          string `json:"release_date"`
 	ItemID               string `json:"item_id"`
 	DurationMS           int    `json:"duration_ms"`
@@ -62,6 +63,7 @@ type DownloadRequest struct {
 	Genre                string `json:"genre,omitempty"`
 	Label                string `json:"label,omitempty"`
 	Copyright            string `json:"copyright,omitempty"`
+	Composer             string `json:"composer,omitempty"`
 	TidalID              string `json:"tidal_id,omitempty"`
 	QobuzID              string `json:"qobuz_id,omitempty"`
 	DeezerID             string `json:"deezer_id,omitempty"`
@@ -72,30 +74,34 @@ type DownloadRequest struct {
 }
 
 type DownloadResponse struct {
-	Success                bool   `json:"success"`
-	Message                string `json:"message"`
-	FilePath               string `json:"file_path,omitempty"`
-	Error                  string `json:"error,omitempty"`
-	ErrorType              string `json:"error_type,omitempty"`
-	AlreadyExists          bool   `json:"already_exists,omitempty"`
-	ActualBitDepth         int    `json:"actual_bit_depth,omitempty"`
-	ActualSampleRate       int    `json:"actual_sample_rate,omitempty"`
-	Service                string `json:"service,omitempty"`
-	Title                  string `json:"title,omitempty"`
-	Artist                 string `json:"artist,omitempty"`
-	Album                  string `json:"album,omitempty"`
-	AlbumArtist            string `json:"album_artist,omitempty"`
-	ReleaseDate            string `json:"release_date,omitempty"`
-	TrackNumber            int    `json:"track_number,omitempty"`
-	DiscNumber             int    `json:"disc_number,omitempty"`
-	ISRC                   string `json:"isrc,omitempty"`
-	CoverURL               string `json:"cover_url,omitempty"`
-	Genre                  string `json:"genre,omitempty"`
-	Label                  string `json:"label,omitempty"`
-	Copyright              string `json:"copyright,omitempty"`
-	SkipMetadataEnrichment bool   `json:"skip_metadata_enrichment,omitempty"`
-	LyricsLRC              string `json:"lyrics_lrc,omitempty"`
-	DecryptionKey          string `json:"decryption_key,omitempty"`
+	Success                bool                    `json:"success"`
+	Message                string                  `json:"message"`
+	FilePath               string                  `json:"file_path,omitempty"`
+	Error                  string                  `json:"error,omitempty"`
+	ErrorType              string                  `json:"error_type,omitempty"`
+	AlreadyExists          bool                    `json:"already_exists,omitempty"`
+	ActualBitDepth         int                     `json:"actual_bit_depth,omitempty"`
+	ActualSampleRate       int                     `json:"actual_sample_rate,omitempty"`
+	Service                string                  `json:"service,omitempty"`
+	Title                  string                  `json:"title,omitempty"`
+	Artist                 string                  `json:"artist,omitempty"`
+	Album                  string                  `json:"album,omitempty"`
+	AlbumArtist            string                  `json:"album_artist,omitempty"`
+	ReleaseDate            string                  `json:"release_date,omitempty"`
+	TrackNumber            int                     `json:"track_number,omitempty"`
+	DiscNumber             int                     `json:"disc_number,omitempty"`
+	TotalTracks            int                     `json:"total_tracks,omitempty"`
+	TotalDiscs             int                     `json:"total_discs,omitempty"`
+	ISRC                   string                  `json:"isrc,omitempty"`
+	CoverURL               string                  `json:"cover_url,omitempty"`
+	Genre                  string                  `json:"genre,omitempty"`
+	Label                  string                  `json:"label,omitempty"`
+	Copyright              string                  `json:"copyright,omitempty"`
+	Composer               string                  `json:"composer,omitempty"`
+	SkipMetadataEnrichment bool                    `json:"skip_metadata_enrichment,omitempty"`
+	LyricsLRC              string                  `json:"lyrics_lrc,omitempty"`
+	DecryptionKey          string                  `json:"decryption_key,omitempty"`
+	Decryption             *DownloadDecryptionInfo `json:"decryption,omitempty"`
 }
 
 type DownloadResult struct {
@@ -107,14 +113,18 @@ type DownloadResult struct {
 	Album         string
 	ReleaseDate   string
 	TrackNumber   int
+	TotalTracks   int
 	DiscNumber    int
+	TotalDiscs    int
 	ISRC          string
 	CoverURL      string
 	Genre         string
 	Label         string
 	Copyright     string
+	Composer      string
 	LyricsLRC     string
 	DecryptionKey string
+	Decryption    *DownloadDecryptionInfo
 }
 
 type reEnrichRequest struct {
@@ -130,11 +140,14 @@ type reEnrichRequest struct {
 	AlbumArtist   string   `json:"album_artist"`
 	TrackNumber   int      `json:"track_number"`
 	DiscNumber    int      `json:"disc_number"`
+	TotalTracks   int      `json:"total_tracks,omitempty"`
+	TotalDiscs    int      `json:"total_discs,omitempty"`
 	ReleaseDate   string   `json:"release_date"`
 	ISRC          string   `json:"isrc"`
 	Genre         string   `json:"genre"`
 	Label         string   `json:"label"`
 	Copyright     string   `json:"copyright"`
+	Composer      string   `json:"composer"`
 	DurationMs    int64    `json:"duration_ms"`
 	SearchOnline  bool     `json:"search_online"`
 	UpdateFields  []string `json:"update_fields,omitempty"`
@@ -172,6 +185,12 @@ func applyReEnrichTrackMetadata(req *reEnrichRequest, track ExtTrackMetadata) {
 	}
 
 	if req.shouldUpdateField("basic_tags") {
+		if track.Name != "" {
+			req.TrackName = track.Name
+		}
+		if track.Artists != "" {
+			req.ArtistName = track.Artists
+		}
 		if track.AlbumName != "" {
 			req.AlbumName = track.AlbumName
 		}
@@ -183,9 +202,15 @@ func applyReEnrichTrackMetadata(req *reEnrichRequest, track ExtTrackMetadata) {
 		if track.TrackNumber > 0 {
 			req.TrackNumber = track.TrackNumber
 		}
+		if track.TotalTracks > 0 {
+			req.TotalTracks = track.TotalTracks
+		}
 		if track.DiscNumber > 0 {
 			req.DiscNumber = track.DiscNumber
 		}
+		if track.TotalDiscs > 0 {
+			req.TotalDiscs = track.TotalDiscs
+		}
 	}
 	if req.shouldUpdateField("release_info") {
 		if track.ReleaseDate != "" {
@@ -213,9 +238,35 @@ func applyReEnrichTrackMetadata(req *reEnrichRequest, track ExtTrackMetadata) {
 		if track.Copyright != "" {
 			req.Copyright = track.Copyright
 		}
+		if track.Composer != "" {
+			req.Composer = track.Composer
+		}
 	}
 }
 
+func isPlaceholderReEnrichValue(value string) bool {
+	switch strings.ToLower(strings.TrimSpace(value)) {
+	case "", "unknown", "unknown artist", "unknown title", "unknown album":
+		return true
+	default:
+		return false
+	}
+}
+
+func buildReEnrichSearchQuery(req reEnrichRequest) string {
+	parts := make([]string, 0, 2)
+	if !isPlaceholderReEnrichValue(req.TrackName) {
+		parts = append(parts, strings.TrimSpace(req.TrackName))
+	}
+	if !isPlaceholderReEnrichValue(req.ArtistName) {
+		parts = append(parts, strings.TrimSpace(req.ArtistName))
+	}
+	if len(parts) == 0 && !isPlaceholderReEnrichValue(req.AlbumName) {
+		parts = append(parts, strings.TrimSpace(req.AlbumName))
+	}
+	return strings.TrimSpace(strings.Join(parts, " "))
+}
+
 func reEnrichDownloadRequest(req reEnrichRequest) DownloadRequest {
 	return DownloadRequest{
 		TrackName:     req.TrackName,
@@ -225,12 +276,23 @@ func reEnrichDownloadRequest(req reEnrichRequest) DownloadRequest {
 		ISRC:          req.ISRC,
 		DurationMS:    int(req.DurationMs),
 		ArtistTagMode: req.ArtistTagMode,
+		TrackNumber:   req.TrackNumber,
+		TotalTracks:   req.TotalTracks,
+		DiscNumber:    req.DiscNumber,
+		TotalDiscs:    req.TotalDiscs,
+		Composer:      req.Composer,
 	}
 }
 
 func buildReEnrichFFmpegMetadata(req *reEnrichRequest, lyricsLRC string) map[string]string {
 	metadata := map[string]string{}
 	if req.shouldUpdateField("basic_tags") {
+		if req.TrackName != "" {
+			metadata["TITLE"] = req.TrackName
+		}
+		if req.ArtistName != "" {
+			metadata["ARTIST"] = req.ArtistName
+		}
 		if req.AlbumName != "" {
 			metadata["ALBUM"] = req.AlbumName
 		}
@@ -256,13 +318,16 @@ func buildReEnrichFFmpegMetadata(req *reEnrichRequest, lyricsLRC string) map[str
 		if req.Copyright != "" {
 			metadata["COPYRIGHT"] = req.Copyright
 		}
+		if req.Composer != "" {
+			metadata["COMPOSER"] = req.Composer
+		}
 	}
 	if req.shouldUpdateField("track_info") {
 		if req.TrackNumber > 0 {
-			metadata["TRACKNUMBER"] = fmt.Sprintf("%d", req.TrackNumber)
+			metadata["TRACKNUMBER"] = formatIndexValue(req.TrackNumber, req.TotalTracks)
 		}
 		if req.DiscNumber > 0 {
-			metadata["DISCNUMBER"] = fmt.Sprintf("%d", req.DiscNumber)
+			metadata["DISCNUMBER"] = formatIndexValue(req.DiscNumber, req.TotalDiscs)
 		}
 	}
 	if req.shouldUpdateField("lyrics") {
@@ -367,11 +432,14 @@ func extTrackFromTrackMetadata(track *TrackMetadata, providerID string) *ExtTrac
 		Images:      track.Images,
 		ReleaseDate: track.ReleaseDate,
 		TrackNumber: track.TrackNumber,
+		TotalTracks: track.TotalTracks,
 		DiscNumber:  track.DiscNumber,
+		TotalDiscs:  track.TotalDiscs,
 		ISRC:        track.ISRC,
 		ProviderID:  providerID,
 		DeezerID:    deezerID,
 		SpotifyID:   track.SpotifyID,
+		Composer:    track.Composer,
 	}
 }
 
@@ -533,6 +601,11 @@ func buildDownloadSuccessResponse(
 		copyright = req.Copyright
 	}
 
+	composer := result.Composer
+	if composer == "" {
+		composer = req.Composer
+	}
+
 	coverURL := strings.TrimSpace(result.CoverURL)
 	if coverURL == "" {
 		coverURL = strings.TrimSpace(req.CoverURL)
@@ -552,14 +625,18 @@ func buildDownloadSuccessResponse(
 		AlbumArtist:      req.AlbumArtist,
 		ReleaseDate:      releaseDate,
 		TrackNumber:      trackNumber,
+		TotalTracks:      req.TotalTracks,
 		DiscNumber:       discNumber,
+		TotalDiscs:       req.TotalDiscs,
 		ISRC:             isrc,
 		CoverURL:         coverURL,
 		Genre:            genre,
 		Label:            label,
 		Copyright:        copyright,
+		Composer:         composer,
 		LyricsLRC:        result.LyricsLRC,
 		DecryptionKey:    result.DecryptionKey,
+		Decryption:       normalizeDownloadDecryptionInfo(result.Decryption, result.DecryptionKey),
 	}
 }
 
@@ -707,24 +784,6 @@ func DownloadTrack(requestJSON string) (string, error) {
 			}
 		}
 		err = qobuzErr
-	case "deezer":
-		deezerResult, deezerErr := downloadFromDeezer(req)
-		if deezerErr == nil {
-			result = DownloadResult{
-				FilePath:    deezerResult.FilePath,
-				BitDepth:    deezerResult.BitDepth,
-				SampleRate:  deezerResult.SampleRate,
-				Title:       deezerResult.Title,
-				Artist:      deezerResult.Artist,
-				Album:       deezerResult.Album,
-				ReleaseDate: deezerResult.ReleaseDate,
-				TrackNumber: deezerResult.TrackNumber,
-				DiscNumber:  deezerResult.DiscNumber,
-				ISRC:        deezerResult.ISRC,
-				LyricsLRC:   deezerResult.LyricsLRC,
-			}
-		}
-		err = deezerErr
 	default:
 		return errorResponse("Unknown service: " + req.Service)
 	}
@@ -775,7 +834,7 @@ func DownloadByStrategy(requestJSON string) (string, error) {
 	serviceNormalized := strings.ToLower(serviceRaw)
 
 	normalizedReq := req
-	if isBuiltInProvider(serviceNormalized) {
+	if isBuiltInDownloadProvider(serviceNormalized) {
 		normalizedReq.Service = serviceNormalized
 	}
 
@@ -788,7 +847,7 @@ func DownloadByStrategy(requestJSON string) (string, error) {
 	if req.UseExtensions {
 		// Respect strict mode when auto fallback is disabled:
 		// for built-in providers, route directly to selected service only.
-		if !req.UseFallback && isBuiltInProvider(serviceNormalized) {
+		if !req.UseFallback && isBuiltInDownloadProvider(serviceNormalized) {
 			return DownloadTrack(normalizedJSON)
 		}
 		resp, err := DownloadWithExtensionsJSON(normalizedJSON)
@@ -827,9 +886,9 @@ func DownloadWithFallback(requestJSON string) (string, error) {
 
 	enrichRequestExtendedMetadata(&req)
 
-	allServices := []string{"tidal", "qobuz", "deezer"}
+	allServices := []string{"tidal", "qobuz"}
 	preferredService := req.Service
-	if preferredService == "" {
+	if !isBuiltInDownloadProvider(preferredService) {
 		preferredService = "tidal"
 	}
 
@@ -895,26 +954,6 @@ func DownloadWithFallback(requestJSON string) (string, error) {
 				GoLog("[DownloadWithFallback] Qobuz error: %v\n", qobuzErr)
 			}
 			err = qobuzErr
-		case "deezer":
-			deezerResult, deezerErr := downloadFromDeezer(req)
-			if deezerErr == nil {
-				result = DownloadResult{
-					FilePath:    deezerResult.FilePath,
-					BitDepth:    deezerResult.BitDepth,
-					SampleRate:  deezerResult.SampleRate,
-					Title:       deezerResult.Title,
-					Artist:      deezerResult.Artist,
-					Album:       deezerResult.Album,
-					ReleaseDate: deezerResult.ReleaseDate,
-					TrackNumber: deezerResult.TrackNumber,
-					DiscNumber:  deezerResult.DiscNumber,
-					ISRC:        deezerResult.ISRC,
-					LyricsLRC:   deezerResult.LyricsLRC,
-				}
-			} else if !errors.Is(deezerErr, ErrDownloadCancelled) {
-				GoLog("[DownloadWithFallback] Deezer error: %v\n", deezerErr)
-			}
-			err = deezerErr
 		}
 
 		if err != nil && errors.Is(err, ErrDownloadCancelled) {
@@ -1005,7 +1044,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 		"album_artist": "",
 		"date":         "",
 		"track_number": 0,
+		"total_tracks": 0,
 		"disc_number":  0,
+		"total_discs":  0,
 		"isrc":         "",
 		"lyrics":       "",
 		"genre":        "",
@@ -1033,7 +1074,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 					result["date"] = oggMeta.Year
 				}
 				result["track_number"] = oggMeta.TrackNumber
+				result["total_tracks"] = oggMeta.TotalTracks
 				result["disc_number"] = oggMeta.DiscNumber
+				result["total_discs"] = oggMeta.TotalDiscs
 				result["isrc"] = oggMeta.ISRC
 				result["lyrics"] = oggMeta.Lyrics
 				result["genre"] = oggMeta.Genre
@@ -1054,7 +1097,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 			result["album_artist"] = metadata.AlbumArtist
 			result["date"] = metadata.Date
 			result["track_number"] = metadata.TrackNumber
+			result["total_tracks"] = metadata.TotalTracks
 			result["disc_number"] = metadata.DiscNumber
+			result["total_discs"] = metadata.TotalDiscs
 			result["isrc"] = metadata.ISRC
 			result["lyrics"] = metadata.Lyrics
 			result["genre"] = metadata.Genre
@@ -1088,7 +1133,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 				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
@@ -1118,7 +1165,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 				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
@@ -1149,7 +1198,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 				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
@@ -1182,7 +1233,9 @@ func ReadFileMetadata(filePath string) (string, error) {
 					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
@@ -1281,13 +1334,21 @@ func EditFileMetadata(filePath, metadataJSON string) (string, error) {
 	// APE/WV/MPC: write APEv2 tags natively
 	if isApeFile {
 		trackNum := 0
+		totalTracks := 0
 		discNum := 0
+		totalDiscs := 0
 		if v, ok := fields["track_number"]; ok && v != "" {
 			fmt.Sscanf(v, "%d", &trackNum)
 		}
+		if v, ok := fields["track_total"]; ok && v != "" {
+			fmt.Sscanf(v, "%d", &totalTracks)
+		}
 		if v, ok := fields["disc_number"]; ok && v != "" {
 			fmt.Sscanf(v, "%d", &discNum)
 		}
+		if v, ok := fields["disc_total"]; ok && v != "" {
+			fmt.Sscanf(v, "%d", &totalDiscs)
+		}
 
 		meta := &AudioMetadata{
 			Title:               fields["title"],
@@ -1296,7 +1357,9 @@ func EditFileMetadata(filePath, metadataJSON string) (string, error) {
 			AlbumArtist:         fields["album_artist"],
 			Date:                fields["date"],
 			TrackNumber:         trackNum,
+			TotalTracks:         totalTracks,
 			DiscNumber:          discNum,
+			TotalDiscs:          totalDiscs,
 			ISRC:                fields["isrc"],
 			Genre:               fields["genre"],
 			Label:               fields["label"],
@@ -1930,11 +1993,13 @@ func buildDeezerISRCSearchResult(track *TrackMetadata) map[string]interface{} {
 		"track_number":  track.TrackNumber,
 		"total_tracks":  track.TotalTracks,
 		"disc_number":   track.DiscNumber,
+		"total_discs":   track.TotalDiscs,
 		"external_urls": track.ExternalURL,
 		"isrc":          track.ISRC,
 		"album_id":      track.AlbumID,
 		"artist_id":     track.ArtistID,
 		"album_type":    track.AlbumType,
+		"composer":      track.Composer,
 	}
 
 	if deezerID := strings.TrimSpace(strings.TrimPrefix(track.SpotifyID, "deezer:")); deezerID != "" {
@@ -2230,14 +2295,12 @@ func ReEnrichFile(requestJSON string) (string, error) {
 
 	// When search_online is true, search for metadata from internet using the
 	// configured metadata-provider priority.
-	if req.SearchOnline && req.TrackName != "" && req.ArtistName != "" {
-		GoLog("[ReEnrich] Searching online metadata for: %s - %s\n", req.TrackName, req.ArtistName)
-		searchQuery := req.TrackName + " " + req.ArtistName
+	if req.SearchOnline {
 		found := false
 
 		deezerClient := GetDeezerClient()
 		GoLog("[ReEnrich] Trying metadata providers in configured priority...\n")
-		manager := GetExtensionManager()
+		manager := getExtensionManager()
 		if identifierTrack, err := resolveReEnrichTrackFromIdentifiers(req); err == nil && identifierTrack != nil {
 			GoLog("[ReEnrich] Identifier-first metadata match (%s): %s - %s (album: %s, date: %s)\n",
 				identifierTrack.ProviderID, identifierTrack.Name, identifierTrack.Artists, identifierTrack.AlbumName, identifierTrack.ReleaseDate)
@@ -2245,17 +2308,23 @@ func ReEnrichFile(requestJSON string) (string, error) {
 			found = true
 		}
 
-		tracks, searchErr := manager.SearchTracksWithMetadataProviders(searchQuery, 5, true)
-		if searchErr == nil && len(tracks) > 0 {
-			track := selectBestReEnrichTrack(req, tracks)
-			if track != nil {
-				GoLog("[ReEnrich] Metadata match (%s): %s - %s (album: %s, date: %s)\n",
-					track.ProviderID, track.Name, track.Artists, track.AlbumName, track.ReleaseDate)
-				applyReEnrichTrackMetadata(&req, *track)
-				found = true
+		searchQuery := buildReEnrichSearchQuery(req)
+		if searchQuery != "" {
+			GoLog("[ReEnrich] Searching online metadata for query: %s\n", searchQuery)
+			tracks, searchErr := manager.SearchTracksWithMetadataProviders(searchQuery, 5, true)
+			if searchErr == nil && len(tracks) > 0 {
+				track := selectBestReEnrichTrack(req, tracks)
+				if track != nil {
+					GoLog("[ReEnrich] Metadata match (%s): %s - %s (album: %s, date: %s)\n",
+						track.ProviderID, track.Name, track.Artists, track.AlbumName, track.ReleaseDate)
+					applyReEnrichTrackMetadata(&req, *track)
+					found = true
+				}
+			} else if searchErr != nil {
+				GoLog("[ReEnrich] Metadata provider search failed: %v\n", searchErr)
 			}
-		} else if searchErr != nil {
-			GoLog("[ReEnrich] Metadata provider search failed: %v\n", searchErr)
+		} else {
+			GoLog("[ReEnrich] Skipping provider search: no usable title/artist/album query\n")
 		}
 
 		// Try to get extended metadata from Deezer if not already set
@@ -2374,12 +2443,16 @@ func ReEnrichFile(requestJSON string) (string, error) {
 		"duration_ms": req.DurationMs,
 	}
 	if req.shouldUpdateField("basic_tags") {
+		enrichedMeta["track_name"] = req.TrackName
+		enrichedMeta["artist_name"] = req.ArtistName
 		enrichedMeta["album_name"] = req.AlbumName
 		enrichedMeta["album_artist"] = req.AlbumArtist
 	}
 	if req.shouldUpdateField("track_info") {
 		enrichedMeta["track_number"] = req.TrackNumber
+		enrichedMeta["total_tracks"] = req.TotalTracks
 		enrichedMeta["disc_number"] = req.DiscNumber
+		enrichedMeta["total_discs"] = req.TotalDiscs
 	}
 	if req.shouldUpdateField("release_info") {
 		enrichedMeta["release_date"] = req.ReleaseDate
@@ -2392,6 +2465,7 @@ func ReEnrichFile(requestJSON string) (string, error) {
 		enrichedMeta["genre"] = req.Genre
 		enrichedMeta["label"] = req.Label
 		enrichedMeta["copyright"] = req.Copyright
+		enrichedMeta["composer"] = req.Composer
 	}
 
 	if isFlac {
@@ -2403,12 +2477,16 @@ func ReEnrichFile(requestJSON string) (string, error) {
 			ArtistTagMode: req.ArtistTagMode,
 		}
 		if req.shouldUpdateField("basic_tags") {
+			metadata.Title = req.TrackName
+			metadata.Artist = req.ArtistName
 			metadata.Album = req.AlbumName
 			metadata.AlbumArtist = req.AlbumArtist
 		}
 		if req.shouldUpdateField("track_info") {
 			metadata.TrackNumber = req.TrackNumber
+			metadata.TotalTracks = req.TotalTracks
 			metadata.DiscNumber = req.DiscNumber
+			metadata.TotalDiscs = req.TotalDiscs
 		}
 		if req.shouldUpdateField("release_info") {
 			metadata.Date = req.ReleaseDate
@@ -2421,6 +2499,7 @@ func ReEnrichFile(requestJSON string) (string, error) {
 			metadata.Genre = req.Genre
 			metadata.Label = req.Label
 			metadata.Copyright = req.Copyright
+			metadata.Composer = req.Composer
 		}
 
 		if len(coverDataBytes) > 0 {
@@ -2471,7 +2550,7 @@ func ReEnrichFile(requestJSON string) (string, error) {
 }
 
 func InitExtensionSystem(extensionsDir, dataDir string) error {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	if err := manager.SetDirectories(extensionsDir, dataDir); err != nil {
 		return err
 	}
@@ -2485,7 +2564,7 @@ func InitExtensionSystem(extensionsDir, dataDir string) error {
 }
 
 func LoadExtensionsFromDir(dirPath string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	loaded, errors := manager.LoadExtensionsFromDirectory(dirPath)
 
 	result := map[string]interface{}{
@@ -2506,7 +2585,7 @@ func LoadExtensionsFromDir(dirPath string) (string, error) {
 }
 
 func LoadExtensionFromPath(filePath string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.LoadExtensionFromFile(filePath)
 	if err != nil {
 		return "", err
@@ -2529,17 +2608,17 @@ func LoadExtensionFromPath(filePath string) (string, error) {
 }
 
 func UnloadExtensionByID(extensionID string) error {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	return manager.UnloadExtension(extensionID)
 }
 
 func RemoveExtensionByID(extensionID string) error {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	return manager.RemoveExtension(extensionID)
 }
 
 func UpgradeExtensionFromPath(filePath string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.UpgradeExtension(filePath)
 	if err != nil {
 		return "", err
@@ -2561,17 +2640,17 @@ func UpgradeExtensionFromPath(filePath string) (string, error) {
 }
 
 func CheckExtensionUpgradeFromPath(filePath string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	return manager.CheckExtensionUpgradeJSON(filePath)
 }
 
 func GetInstalledExtensions() (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	return manager.GetInstalledExtensionsJSON()
 }
 
 func SetExtensionEnabledByID(extensionID string, enabled bool) error {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	return manager.SetExtensionEnabled(extensionID, enabled)
 }
 
@@ -2594,6 +2673,30 @@ func GetProviderPriorityJSON() (string, error) {
 	return string(jsonBytes), nil
 }
 
+func SetExtensionFallbackProviderIDsJSON(providerIDsJSON string) error {
+	if strings.TrimSpace(providerIDsJSON) == "" {
+		SetExtensionFallbackProviderIDs(nil)
+		return nil
+	}
+
+	var providerIDs []string
+	if err := json.Unmarshal([]byte(providerIDsJSON), &providerIDs); err != nil {
+		return err
+	}
+
+	SetExtensionFallbackProviderIDs(providerIDs)
+	return nil
+}
+
+func GetExtensionFallbackProviderIDsJSON() (string, error) {
+	providerIDs := GetExtensionFallbackProviderIDs()
+	jsonBytes, err := json.Marshal(providerIDs)
+	if err != nil {
+		return "", err
+	}
+	return string(jsonBytes), nil
+}
+
 func SetMetadataProviderPriorityJSON(priorityJSON string) error {
 	var priority []string
 	if err := json.Unmarshal([]byte(priorityJSON), &priority); err != nil {
@@ -2636,12 +2739,12 @@ func SetExtensionSettingsJSON(extensionID, settingsJSON string) error {
 		return err
 	}
 
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	return manager.InitializeExtension(extensionID, settings)
 }
 
 func SearchTracksWithExtensionsJSON(query string, limit int) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	tracks, err := manager.SearchTracksWithExtensions(query, limit)
 	if err != nil {
 		return "", err
@@ -2656,7 +2759,7 @@ func SearchTracksWithExtensionsJSON(query string, limit int) (string, error) {
 }
 
 func SearchTracksWithMetadataProvidersJSON(query string, limit int, includeExtensions bool) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	tracks, err := manager.SearchTracksWithMetadataProviders(query, limit, includeExtensions)
 	if err != nil {
 		return "", err
@@ -2703,12 +2806,12 @@ func DownloadWithExtensionsJSON(requestJSON string) (string, error) {
 }
 
 func CleanupExtensions() {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	manager.UnloadAllExtensions()
 }
 
 func InvokeExtensionActionJSON(extensionID, actionName string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	result, err := manager.InvokeAction(extensionID, actionName)
 	if err != nil {
 		return "", err
@@ -2845,7 +2948,7 @@ func GetAllPendingFFmpegCommandsJSON() (string, error) {
 }
 
 func EnrichTrackWithExtensionJSON(extensionID, trackJSON string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.GetExtension(extensionID)
 	if err != nil {
 		return trackJSON, nil
@@ -2860,7 +2963,7 @@ func EnrichTrackWithExtensionJSON(extensionID, trackJSON string) (string, error)
 		return trackJSON, fmt.Errorf("failed to parse track: %w", err)
 	}
 
-	provider := NewExtensionProviderWrapper(ext)
+	provider := newExtensionProviderWrapper(ext)
 	enrichedTrack, err := provider.EnrichTrack(&track)
 	if err != nil {
 		return trackJSON, nil
@@ -2875,7 +2978,7 @@ func EnrichTrackWithExtensionJSON(extensionID, trackJSON string) (string, error)
 }
 
 func CustomSearchWithExtensionJSON(extensionID, query string, optionsJSON string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.GetExtension(extensionID)
 	if err != nil {
 		return "", err
@@ -2892,7 +2995,7 @@ func CustomSearchWithExtensionJSON(extensionID, query string, optionsJSON string
 		}
 	}
 
-	provider := NewExtensionProviderWrapper(ext)
+	provider := newExtensionProviderWrapper(ext)
 	tracks, err := provider.CustomSearch(query, options)
 	if err != nil {
 		return "", err
@@ -2910,11 +3013,14 @@ func CustomSearchWithExtensionJSON(extensionID, query string, optionsJSON string
 			"images":       track.ResolvedCoverURL(),
 			"release_date": track.ReleaseDate,
 			"track_number": track.TrackNumber,
+			"total_tracks": track.TotalTracks,
 			"disc_number":  track.DiscNumber,
+			"total_discs":  track.TotalDiscs,
 			"isrc":         track.ISRC,
 			"provider_id":  track.ProviderID,
 			"item_type":    track.ItemType,
 			"album_type":   track.AlbumType,
+			"composer":     track.Composer,
 		}
 	}
 
@@ -2927,7 +3033,7 @@ func CustomSearchWithExtensionJSON(extensionID, query string, optionsJSON string
 }
 
 func GetSearchProvidersJSON() (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	providers := manager.GetSearchProviders()
 
 	result := make([]map[string]interface{}, 0, len(providers))
@@ -2950,7 +3056,7 @@ func GetSearchProvidersJSON() (string, error) {
 }
 
 func HandleURLWithExtensionJSON(url string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	resultWithID, err := manager.HandleURLWithExtension(url)
 	if err != nil {
 		return "", err
@@ -2981,9 +3087,12 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 			"images":       result.Track.ResolvedCoverURL(),
 			"release_date": result.Track.ReleaseDate,
 			"track_number": result.Track.TrackNumber,
+			"total_tracks": result.Track.TotalTracks,
 			"disc_number":  result.Track.DiscNumber,
+			"total_discs":  result.Track.TotalDiscs,
 			"isrc":         result.Track.ISRC,
 			"provider_id":  result.Track.ProviderID,
+			"composer":     result.Track.Composer,
 		}
 	}
 
@@ -3000,11 +3109,14 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 				"images":       track.ResolvedCoverURL(),
 				"release_date": track.ReleaseDate,
 				"track_number": track.TrackNumber,
+				"total_tracks": track.TotalTracks,
 				"disc_number":  track.DiscNumber,
+				"total_discs":  track.TotalDiscs,
 				"isrc":         track.ISRC,
 				"provider_id":  track.ProviderID,
 				"item_type":    track.ItemType,
 				"album_type":   track.AlbumType,
+				"composer":     track.Composer,
 			}
 		}
 		response["tracks"] = tracks
@@ -3090,10 +3202,13 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 					"images":       track.ResolvedCoverURL(),
 					"release_date": track.ReleaseDate,
 					"track_number": track.TrackNumber,
+					"total_tracks": track.TotalTracks,
 					"disc_number":  track.DiscNumber,
+					"total_discs":  track.TotalDiscs,
 					"isrc":         track.ISRC,
 					"provider_id":  track.ProviderID,
 					"spotify_id":   track.SpotifyID,
+					"composer":     track.Composer,
 				}
 			}
 			artistResponse["top_tracks"] = topTracks
@@ -3111,7 +3226,7 @@ func HandleURLWithExtensionJSON(url string) (string, error) {
 }
 
 func FindURLHandlerJSON(url string) string {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	handler := manager.FindURLHandler(url)
 	if handler == nil {
 		return ""
@@ -3120,7 +3235,7 @@ func FindURLHandlerJSON(url string) string {
 }
 
 func GetAlbumWithExtensionJSON(extensionID, albumID string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.GetExtension(extensionID)
 	if err != nil {
 		return "", err
@@ -3133,7 +3248,7 @@ func GetAlbumWithExtensionJSON(extensionID, albumID string) (string, error) {
 		return "", fmt.Errorf("extension '%s' is disabled", extensionID)
 	}
 
-	provider := NewExtensionProviderWrapper(ext)
+	provider := newExtensionProviderWrapper(ext)
 	album, err := provider.GetAlbum(albumID)
 	if err != nil {
 		return "", err
@@ -3163,11 +3278,14 @@ func GetAlbumWithExtensionJSON(extensionID, albumID string) (string, error) {
 			"cover_url":    trackCover,
 			"release_date": track.ReleaseDate,
 			"track_number": trackNum,
+			"total_tracks": track.TotalTracks,
 			"disc_number":  track.DiscNumber,
+			"total_discs":  track.TotalDiscs,
 			"isrc":         track.ISRC,
 			"provider_id":  track.ProviderID,
 			"item_type":    track.ItemType,
 			"album_type":   track.AlbumType,
+			"composer":     track.Composer,
 		}
 	}
 
@@ -3193,7 +3311,7 @@ func GetAlbumWithExtensionJSON(extensionID, albumID string) (string, error) {
 }
 
 func GetPlaylistWithExtensionJSON(extensionID, playlistID string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.GetExtension(extensionID)
 	if err != nil {
 		return "", err
@@ -3264,11 +3382,14 @@ func GetPlaylistWithExtensionJSON(extensionID, playlistID string) (string, error
 			"cover_url":    trackCover,
 			"release_date": track.ReleaseDate,
 			"track_number": track.TrackNumber,
+			"total_tracks": track.TotalTracks,
 			"disc_number":  track.DiscNumber,
+			"total_discs":  track.TotalDiscs,
 			"isrc":         track.ISRC,
 			"provider_id":  track.ProviderID,
 			"item_type":    track.ItemType,
 			"album_type":   track.AlbumType,
+			"composer":     track.Composer,
 		}
 	}
 
@@ -3291,7 +3412,7 @@ func GetPlaylistWithExtensionJSON(extensionID, playlistID string) (string, error
 }
 
 func GetArtistWithExtensionJSON(extensionID, artistID string) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.GetExtension(extensionID)
 	if err != nil {
 		return "", err
@@ -3301,7 +3422,7 @@ func GetArtistWithExtensionJSON(extensionID, artistID string) (string, error) {
 		return "", fmt.Errorf("extension '%s' is not a metadata provider", extensionID)
 	}
 
-	provider := NewExtensionProviderWrapper(ext)
+	provider := newExtensionProviderWrapper(ext)
 	artist, err := provider.GetArtist(artistID)
 	if err != nil {
 		return "", err
@@ -3375,10 +3496,13 @@ func GetArtistWithExtensionJSON(extensionID, artistID string) (string, error) {
 				"images":       track.ResolvedCoverURL(),
 				"release_date": track.ReleaseDate,
 				"track_number": track.TrackNumber,
+				"total_tracks": track.TotalTracks,
 				"disc_number":  track.DiscNumber,
+				"total_discs":  track.TotalDiscs,
 				"isrc":         track.ISRC,
 				"provider_id":  track.ProviderID,
 				"spotify_id":   track.SpotifyID,
+				"composer":     track.Composer,
 			}
 		}
 		response["top_tracks"] = topTracks
@@ -3393,7 +3517,7 @@ func GetArtistWithExtensionJSON(extensionID, artistID string) (string, error) {
 }
 
 func GetURLHandlersJSON() (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	handlers := manager.GetURLHandlers()
 
 	result := make([]map[string]interface{}, 0, len(handlers))
@@ -3421,7 +3545,7 @@ func RunPostProcessingJSON(filePath, metadataJSON string) (string, error) {
 		}
 	}
 
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	result, err := manager.RunPostProcessing(filePath, metadata)
 	if err != nil {
 		return "", err
@@ -3450,7 +3574,7 @@ func RunPostProcessingV2JSON(inputJSON, metadataJSON string) (string, error) {
 		}
 	}
 
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	result, err := manager.RunPostProcessingV2(input, metadata)
 	if err != nil {
 		return "", err
@@ -3465,7 +3589,7 @@ func RunPostProcessingV2JSON(inputJSON, metadataJSON string) (string, error) {
 }
 
 func GetPostProcessingProvidersJSON() (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	providers := manager.GetPostProcessingProviders()
 
 	result := make([]map[string]interface{}, 0, len(providers))
@@ -3631,7 +3755,7 @@ func ClearStoreCacheJSON() error {
 }
 
 func callExtensionFunctionJSON(extensionID, functionName string, timeout time.Duration) (string, error) {
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	ext, err := manager.GetExtension(extensionID)
 	if err != nil {
 		return "", err

go_backend/exports_test.go

@@ -2,6 +2,21 @@ package gobackend
 
 import "testing"
 
+func TestSetExtensionFallbackProviderIDsJSONEmptyStringResetsDefault(t *testing.T) {
+	original := GetExtensionFallbackProviderIDs()
+	defer SetExtensionFallbackProviderIDs(original)
+
+	SetExtensionFallbackProviderIDs([]string{"custom-ext"})
+
+	if err := SetExtensionFallbackProviderIDsJSON(""); err != nil {
+		t.Fatalf("SetExtensionFallbackProviderIDsJSON returned error: %v", err)
+	}
+
+	if got := GetExtensionFallbackProviderIDs(); got != nil {
+		t.Fatalf("expected nil fallback provider list after reset, got %v", got)
+	}
+}
+
 func TestBuildDownloadSuccessResponsePrefersRequestedAlbumMetadata(t *testing.T) {
 	req := DownloadRequest{
 		TrackName:   "Bonus Track",
@@ -114,6 +129,38 @@ func TestBuildDownloadSuccessResponsePrefersProviderCoverURL(t *testing.T) {
 	}
 }
 
+func TestBuildDownloadSuccessResponseNormalizesDecryptionDescriptor(t *testing.T) {
+	req := DownloadRequest{
+		TrackName:  "Track",
+		ArtistName: "Artist",
+	}
+
+	result := DownloadResult{
+		Title:         "Track",
+		Artist:        "Artist",
+		DecryptionKey: "00112233",
+	}
+
+	resp := buildDownloadSuccessResponse(
+		req,
+		result,
+		"amazon",
+		"ok",
+		"/tmp/test.m4a",
+		false,
+	)
+
+	if resp.Decryption == nil {
+		t.Fatal("expected decryption descriptor to be present")
+	}
+	if resp.Decryption.Strategy != genericFFmpegMOVDecryptionStrategy {
+		t.Fatalf("strategy = %q", resp.Decryption.Strategy)
+	}
+	if resp.Decryption.Key != result.DecryptionKey {
+		t.Fatalf("key = %q, want %q", resp.Decryption.Key, result.DecryptionKey)
+	}
+}
+
 func TestApplyReEnrichTrackMetadataPreservesExistingReleaseDateWhenCandidateMissing(t *testing.T) {
 	req := reEnrichRequest{
 		SpotifyID:   "spotify-track-id",
@@ -195,13 +242,11 @@ func TestBuildReEnrichFFmpegMetadataOmitsEmptyFields(t *testing.T) {
 
 	metadata := buildReEnrichFFmpegMetadata(&req, "")
 
-	// Title and Artist are never written by re-enrich (they are search keys
-	// preserved as-is from the file).
-	if _, exists := metadata["TITLE"]; exists {
-		t.Fatalf("TITLE should not be in metadata: %#v", metadata)
+	if metadata["TITLE"] != "Song" {
+		t.Fatalf("title = %q", metadata["TITLE"])
 	}
-	if _, exists := metadata["ARTIST"]; exists {
-		t.Fatalf("ARTIST should not be in metadata: %#v", metadata)
+	if metadata["ARTIST"] != "Artist" {
+		t.Fatalf("artist = %q", metadata["ARTIST"])
 	}
 	if metadata["ALBUM"] != "Album" {
 		t.Fatalf("album = %q", metadata["ALBUM"])
@@ -224,3 +269,75 @@ func TestBuildReEnrichFFmpegMetadataOmitsEmptyFields(t *testing.T) {
 		}
 	}
 }
+
+func TestBuildReEnrichSearchQuerySkipsPlaceholderArtist(t *testing.T) {
+	req := reEnrichRequest{
+		TrackName:  "Sign of the Times",
+		ArtistName: "Unknown Artist",
+		AlbumName:  "Harry Styles",
+	}
+
+	query := buildReEnrichSearchQuery(req)
+	if query != "Sign of the Times" {
+		t.Fatalf("query = %q", query)
+	}
+
+	req = reEnrichRequest{
+		TrackName:  "Unknown Title",
+		ArtistName: "Unknown Artist",
+		AlbumName:  "Harry Styles",
+	}
+	query = buildReEnrichSearchQuery(req)
+	if query != "Harry Styles" {
+		t.Fatalf("fallback album query = %q", query)
+	}
+}
+
+func TestApplyReEnrichTrackMetadataCopiesComposerAndTotals(t *testing.T) {
+	req := reEnrichRequest{}
+
+	applyReEnrichTrackMetadata(&req, ExtTrackMetadata{
+		Name:        "Resolved Song",
+		Artists:     "Resolved Artist",
+		TrackNumber: 7,
+		TotalTracks: 12,
+		DiscNumber:  2,
+		TotalDiscs:  3,
+		Composer:    "Composer",
+	})
+
+	if req.TrackNumber != 7 || req.TotalTracks != 12 {
+		t.Fatalf("track metadata = %d/%d", req.TrackNumber, req.TotalTracks)
+	}
+	if req.DiscNumber != 2 || req.TotalDiscs != 3 {
+		t.Fatalf("disc metadata = %d/%d", req.DiscNumber, req.TotalDiscs)
+	}
+	if req.TrackName != "Resolved Song" || req.ArtistName != "Resolved Artist" {
+		t.Fatalf("basic tags = %q / %q", req.TrackName, req.ArtistName)
+	}
+	if req.Composer != "Composer" {
+		t.Fatalf("composer = %q", req.Composer)
+	}
+}
+
+func TestBuildReEnrichFFmpegMetadataFormatsTotalsAndComposer(t *testing.T) {
+	req := reEnrichRequest{
+		TrackNumber: 7,
+		TotalTracks: 12,
+		DiscNumber:  2,
+		TotalDiscs:  3,
+		Composer:    "Composer",
+	}
+
+	metadata := buildReEnrichFFmpegMetadata(&req, "")
+
+	if metadata["TRACKNUMBER"] != "7/12" {
+		t.Fatalf("TRACKNUMBER = %q", metadata["TRACKNUMBER"])
+	}
+	if metadata["DISCNUMBER"] != "2/3" {
+		t.Fatalf("DISCNUMBER = %q", metadata["DISCNUMBER"])
+	}
+	if metadata["COMPOSER"] != "Composer" {
+		t.Fatalf("COMPOSER = %q", metadata["COMPOSER"])
+	}
+}

go_backend/extension_manager.go

@@ -43,12 +43,12 @@ func compareVersions(v1, v2 string) int {
 	return 0
 }
 
-type LoadedExtension struct {
+type loadedExtension struct {
 	ID          string             `json:"id"`
 	Manifest    *ExtensionManifest `json:"manifest"`
 	VM          *goja.Runtime      `json:"-"`
 	VMMu        sync.Mutex         `json:"-"`
-	runtime     *ExtensionRuntime
+	runtime     *extensionRuntime
 	initialized bool
 	Enabled     bool   `json:"enabled"`
 	Error       string `json:"error,omitempty"`
@@ -73,7 +73,7 @@ func getExtensionInitSettings(extensionID string) map[string]interface{} {
 	return filtered
 }
 
-func ensureRuntimeReadyLocked(ext *LoadedExtension, applyStoredSettings bool) error {
+func ensureRuntimeReadyLocked(ext *loadedExtension, applyStoredSettings bool) error {
 	if ext.VM == nil || ext.runtime == nil {
 		if err := initializeVMLocked(ext); err != nil {
 			ext.Error = err.Error()
@@ -100,14 +100,14 @@ func ensureRuntimeReadyLocked(ext *LoadedExtension, applyStoredSettings bool) er
 	return nil
 }
 
-func (ext *LoadedExtension) ensureRuntimeReady() error {
+func (ext *loadedExtension) ensureRuntimeReady() error {
 	ext.VMMu.Lock()
 	defer ext.VMMu.Unlock()
 
 	return ensureRuntimeReadyLocked(ext, true)
 }
 
-func (ext *LoadedExtension) lockReadyVM() (*goja.Runtime, error) {
+func (ext *loadedExtension) lockReadyVM() (*goja.Runtime, error) {
 	ext.VMMu.Lock()
 	if err := ensureRuntimeReadyLocked(ext, true); err != nil {
 		ext.VMMu.Unlock()
@@ -116,28 +116,28 @@ func (ext *LoadedExtension) lockReadyVM() (*goja.Runtime, error) {
 	return ext.VM, nil
 }
 
-type ExtensionManager struct {
+type extensionManager struct {
 	mu            sync.RWMutex
-	extensions    map[string]*LoadedExtension
+	extensions    map[string]*loadedExtension
 	extensionsDir string
 	dataDir       string
 }
 
 var (
-	globalExtManager     *ExtensionManager
+	globalExtManager     *extensionManager
 	globalExtManagerOnce sync.Once
 )
 
-func GetExtensionManager() *ExtensionManager {
+func getExtensionManager() *extensionManager {
 	globalExtManagerOnce.Do(func() {
-		globalExtManager = &ExtensionManager{
-			extensions: make(map[string]*LoadedExtension),
+		globalExtManager = &extensionManager{
+			extensions: make(map[string]*loadedExtension),
 		}
 	})
 	return globalExtManager
 }
 
-func (m *ExtensionManager) SetDirectories(extensionsDir, dataDir string) error {
+func (m *extensionManager) SetDirectories(extensionsDir, dataDir string) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -154,7 +154,7 @@ func (m *ExtensionManager) SetDirectories(extensionsDir, dataDir string) error {
 	return nil
 }
 
-func (m *ExtensionManager) LoadExtensionFromFile(filePath string) (*LoadedExtension, 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")
 	}
@@ -272,7 +272,7 @@ func (m *ExtensionManager) LoadExtensionFromFile(filePath string) (*LoadedExtens
 		return nil, fmt.Errorf("failed to create extension data directory: %w", err)
 	}
 
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID:        manifest.Name,
 		Manifest:  manifest,
 		Enabled:   false, // New extensions start disabled
@@ -292,7 +292,7 @@ func (m *ExtensionManager) LoadExtensionFromFile(filePath string) (*LoadedExtens
 	return ext, nil
 }
 
-func initializeVMLocked(ext *LoadedExtension) error {
+func initializeVMLocked(ext *loadedExtension) error {
 	ext.VM = nil
 	ext.runtime = nil
 	ext.initialized = false
@@ -305,7 +305,7 @@ func initializeVMLocked(ext *LoadedExtension) error {
 		return fmt.Errorf("failed to read index.js: %w", err)
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 	ext.runtime = runtime
 	runtime.RegisterAPIs(vm)
 	runtime.RegisterGoBackendAPIs(vm)
@@ -342,14 +342,14 @@ func initializeVMLocked(ext *LoadedExtension) error {
 	return nil
 }
 
-func (m *ExtensionManager) initializeVM(ext *LoadedExtension) error {
+func (m *extensionManager) initializeVM(ext *loadedExtension) error {
 	ext.VMMu.Lock()
 	defer ext.VMMu.Unlock()
 	return initializeVMLocked(ext)
 }
 
 func initializeExtensionWithSettingsLocked(
-	ext *LoadedExtension,
+	ext *loadedExtension,
 	settings map[string]interface{},
 ) error {
 	if ext.VM == nil {
@@ -405,7 +405,7 @@ func initializeExtensionWithSettingsLocked(
 	return nil
 }
 
-func runCleanupLocked(ext *LoadedExtension) error {
+func runCleanupLocked(ext *loadedExtension) error {
 	if ext.VM != nil {
 		script := `
 			(function() {
@@ -446,7 +446,7 @@ func runCleanupLocked(ext *LoadedExtension) error {
 	return nil
 }
 
-func teardownVMLocked(ext *LoadedExtension) {
+func teardownVMLocked(ext *loadedExtension) {
 	if err := runCleanupLocked(ext); err != nil {
 		GoLog("[Extension] Error calling cleanup for %s: %v\n", ext.ID, err)
 	}
@@ -461,7 +461,7 @@ func teardownVMLocked(ext *LoadedExtension) {
 	ext.initialized = false
 }
 
-func validateExtensionLoad(ext *LoadedExtension) error {
+func validateExtensionLoad(ext *loadedExtension) error {
 	ext.VMMu.Lock()
 	defer ext.VMMu.Unlock()
 
@@ -472,7 +472,7 @@ func validateExtensionLoad(ext *LoadedExtension) error {
 	return nil
 }
 
-func (m *ExtensionManager) UnloadExtension(extensionID string) error {
+func (m *extensionManager) UnloadExtension(extensionID string) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -491,7 +491,7 @@ func (m *ExtensionManager) UnloadExtension(extensionID string) error {
 	return nil
 }
 
-func (m *ExtensionManager) GetExtension(extensionID string) (*LoadedExtension, error) {
+func (m *extensionManager) GetExtension(extensionID string) (*loadedExtension, error) {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
@@ -502,18 +502,18 @@ func (m *ExtensionManager) GetExtension(extensionID string) (*LoadedExtension, e
 	return ext, nil
 }
 
-func (m *ExtensionManager) GetAllExtensions() []*LoadedExtension {
+func (m *extensionManager) GetAllExtensions() []*loadedExtension {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	result := make([]*LoadedExtension, 0, len(m.extensions))
+	result := make([]*loadedExtension, 0, len(m.extensions))
 	for _, ext := range m.extensions {
 		result = append(result, ext)
 	}
 	return result
 }
 
-func (m *ExtensionManager) SetExtensionEnabled(extensionID string, enabled bool) error {
+func (m *extensionManager) SetExtensionEnabled(extensionID string, enabled bool) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -547,7 +547,7 @@ func (m *ExtensionManager) SetExtensionEnabled(extensionID string, enabled bool)
 	return nil
 }
 
-func (m *ExtensionManager) LoadExtensionsFromDirectory(dirPath string) ([]string, []error) {
+func (m *extensionManager) LoadExtensionsFromDirectory(dirPath string) ([]string, []error) {
 	var loaded []string
 	var errors []error
 
@@ -585,7 +585,7 @@ func (m *ExtensionManager) LoadExtensionsFromDirectory(dirPath string) ([]string
 	return loaded, errors
 }
 
-func (m *ExtensionManager) loadExtensionFromDirectory(dirPath string) (*LoadedExtension, error) {
+func (m *extensionManager) loadExtensionFromDirectory(dirPath string) (*loadedExtension, error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -615,7 +615,7 @@ func (m *ExtensionManager) loadExtensionFromDirectory(dirPath string) (*LoadedEx
 		return nil, fmt.Errorf("failed to create extension data directory: %w", err)
 	}
 
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID:        manifest.Name,
 		Manifest:  manifest,
 		Enabled:   false, // Will be restored from settings store
@@ -643,7 +643,7 @@ func (m *ExtensionManager) loadExtensionFromDirectory(dirPath string) (*LoadedEx
 	return ext, nil
 }
 
-func (m *ExtensionManager) RemoveExtension(extensionID string) error {
+func (m *extensionManager) RemoveExtension(extensionID string) error {
 	ext, err := m.GetExtension(extensionID)
 	if err != nil {
 		return err
@@ -663,7 +663,7 @@ func (m *ExtensionManager) RemoveExtension(extensionID string) error {
 }
 
 // Only allows upgrades (new version > current version), not downgrades
-func (m *ExtensionManager) UpgradeExtension(filePath string) (*LoadedExtension, error) {
+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")
 	}
@@ -777,7 +777,7 @@ func (m *ExtensionManager) UpgradeExtension(filePath string) (*LoadedExtension,
 		}
 	}
 
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID:        newManifest.Name,
 		Manifest:  newManifest,
 		Enabled:   wasEnabled, // Preserve enabled state from before upgrade
@@ -812,7 +812,7 @@ type ExtensionUpgradeInfo struct {
 	IsInstalled    bool   `json:"is_installed"`
 }
 
-func (m *ExtensionManager) checkExtensionUpgradeInternal(filePath string) (*ExtensionUpgradeInfo, error) {
+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")
 	}
@@ -871,7 +871,7 @@ func (m *ExtensionManager) checkExtensionUpgradeInternal(filePath string) (*Exte
 	return info, nil
 }
 
-func (m *ExtensionManager) CheckExtensionUpgradeJSON(filePath string) (string, error) {
+func (m *extensionManager) CheckExtensionUpgradeJSON(filePath string) (string, error) {
 	info, err := m.checkExtensionUpgradeInternal(filePath)
 	if err != nil {
 		return "", err
@@ -885,7 +885,7 @@ func (m *ExtensionManager) CheckExtensionUpgradeJSON(filePath string) (string, e
 	return string(jsonBytes), nil
 }
 
-func (m *ExtensionManager) GetInstalledExtensionsJSON() (string, error) {
+func (m *extensionManager) GetInstalledExtensionsJSON() (string, error) {
 	extensions := m.GetAllExtensions()
 
 	type ExtensionInfo struct {
@@ -982,7 +982,7 @@ func (m *ExtensionManager) GetInstalledExtensionsJSON() (string, error) {
 	return string(jsonBytes), nil
 }
 
-func (m *ExtensionManager) InitializeExtension(extensionID string, settings map[string]interface{}) error {
+func (m *extensionManager) InitializeExtension(extensionID string, settings map[string]interface{}) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -1000,7 +1000,7 @@ func (m *ExtensionManager) InitializeExtension(extensionID string, settings map[
 	return initializeExtensionWithSettingsLocked(ext, settings)
 }
 
-func (m *ExtensionManager) CleanupExtension(extensionID string) error {
+func (m *extensionManager) CleanupExtension(extensionID string) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -1022,7 +1022,7 @@ func (m *ExtensionManager) CleanupExtension(extensionID string) error {
 	return nil
 }
 
-func (m *ExtensionManager) UnloadAllExtensions() {
+func (m *extensionManager) UnloadAllExtensions() {
 	m.mu.Lock()
 	extensionIDs := make([]string, 0, len(m.extensions))
 	for id := range m.extensions {
@@ -1037,7 +1037,7 @@ func (m *ExtensionManager) UnloadAllExtensions() {
 	GoLog("[Extension] All extensions unloaded\n")
 }
 
-func (m *ExtensionManager) InvokeAction(extensionID string, actionName string) (map[string]interface{}, error) {
+func (m *extensionManager) InvokeAction(extensionID string, actionName string) (map[string]interface{}, error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 

go_backend/extension_providers.go

@@ -26,7 +26,9 @@ type ExtTrackMetadata struct {
 	Images      string `json:"images,omitempty"`
 	ReleaseDate string `json:"release_date,omitempty"`
 	TrackNumber int    `json:"track_number,omitempty"`
+	TotalTracks int    `json:"total_tracks,omitempty"`
 	DiscNumber  int    `json:"disc_number,omitempty"`
+	TotalDiscs  int    `json:"total_discs,omitempty"`
 	ISRC        string `json:"isrc,omitempty"`
 	ProviderID  string `json:"provider_id"`
 	ItemType    string `json:"item_type,omitempty"`
@@ -41,6 +43,7 @@ type ExtTrackMetadata struct {
 	Label     string `json:"label,omitempty"`
 	Copyright string `json:"copyright,omitempty"`
 	Genre     string `json:"genre,omitempty"`
+	Composer  string `json:"composer,omitempty"`
 }
 
 func (t *ExtTrackMetadata) ResolvedCoverURL() string {
@@ -93,6 +96,15 @@ type ExtDownloadURLResult struct {
 	SampleRate int    `json:"sample_rate,omitempty"`
 }
 
+type DownloadDecryptionInfo struct {
+	Strategy        string                 `json:"strategy,omitempty"`
+	Key             string                 `json:"key,omitempty"`
+	IV              string                 `json:"iv,omitempty"`
+	InputFormat     string                 `json:"input_format,omitempty"`
+	OutputExtension string                 `json:"output_extension,omitempty"`
+	Options         map[string]interface{} `json:"options,omitempty"`
+}
+
 type ExtDownloadResult struct {
 	Success      bool   `json:"success"`
 	FilePath     string `json:"file_path,omitempty"`
@@ -101,31 +113,105 @@ type ExtDownloadResult struct {
 	ErrorMessage string `json:"error_message,omitempty"`
 	ErrorType    string `json:"error_type,omitempty"`
 
-	Title         string `json:"title,omitempty"`
-	Artist        string `json:"artist,omitempty"`
-	Album         string `json:"album,omitempty"`
-	AlbumArtist   string `json:"album_artist,omitempty"`
-	TrackNumber   int    `json:"track_number,omitempty"`
-	DiscNumber    int    `json:"disc_number,omitempty"`
-	ReleaseDate   string `json:"release_date,omitempty"`
-	CoverURL      string `json:"cover_url,omitempty"`
-	ISRC          string `json:"isrc,omitempty"`
-	DecryptionKey string `json:"decryption_key,omitempty"`
+	Title         string                  `json:"title,omitempty"`
+	Artist        string                  `json:"artist,omitempty"`
+	Album         string                  `json:"album,omitempty"`
+	AlbumArtist   string                  `json:"album_artist,omitempty"`
+	TrackNumber   int                     `json:"track_number,omitempty"`
+	DiscNumber    int                     `json:"disc_number,omitempty"`
+	ReleaseDate   string                  `json:"release_date,omitempty"`
+	CoverURL      string                  `json:"cover_url,omitempty"`
+	ISRC          string                  `json:"isrc,omitempty"`
+	DecryptionKey string                  `json:"decryption_key,omitempty"`
+	Decryption    *DownloadDecryptionInfo `json:"decryption,omitempty"`
 }
 
-type ExtensionProviderWrapper struct {
-	extension *LoadedExtension
+const genericFFmpegMOVDecryptionStrategy = "ffmpeg.mov_key"
+
+func cloneDownloadDecryptionInfo(info *DownloadDecryptionInfo) *DownloadDecryptionInfo {
+	if info == nil {
+		return nil
+	}
+
+	cloned := &DownloadDecryptionInfo{
+		Strategy:        strings.TrimSpace(info.Strategy),
+		Key:             strings.TrimSpace(info.Key),
+		IV:              strings.TrimSpace(info.IV),
+		InputFormat:     strings.TrimSpace(info.InputFormat),
+		OutputExtension: strings.TrimSpace(info.OutputExtension),
+	}
+	if len(info.Options) > 0 {
+		cloned.Options = make(map[string]interface{}, len(info.Options))
+		for key, value := range info.Options {
+			cloned.Options[key] = value
+		}
+	}
+	return cloned
+}
+
+func normalizeDownloadDecryptionStrategy(strategy string) string {
+	switch strings.ToLower(strings.TrimSpace(strategy)) {
+	case "", "ffmpeg.mov_key", "ffmpeg_mov_key", "mov_decryption_key", "mp4_decryption_key", "ffmpeg.mp4_decryption_key":
+		return genericFFmpegMOVDecryptionStrategy
+	default:
+		return strings.TrimSpace(strategy)
+	}
+}
+
+func normalizeDownloadDecryptionInfo(info *DownloadDecryptionInfo, legacyKey string) *DownloadDecryptionInfo {
+	normalized := cloneDownloadDecryptionInfo(info)
+	trimmedLegacyKey := strings.TrimSpace(legacyKey)
+
+	if normalized == nil {
+		if trimmedLegacyKey == "" {
+			return nil
+		}
+		return &DownloadDecryptionInfo{
+			Strategy:    genericFFmpegMOVDecryptionStrategy,
+			Key:         trimmedLegacyKey,
+			InputFormat: "mov",
+		}
+	}
+
+	normalized.Strategy = normalizeDownloadDecryptionStrategy(normalized.Strategy)
+	if normalized.Key == "" && trimmedLegacyKey != "" {
+		normalized.Key = trimmedLegacyKey
+	}
+	if normalized.Strategy == "" && normalized.Key != "" {
+		normalized.Strategy = genericFFmpegMOVDecryptionStrategy
+	}
+	if normalized.Strategy == genericFFmpegMOVDecryptionStrategy && normalized.InputFormat == "" {
+		normalized.InputFormat = "mov"
+	}
+	if normalized.Strategy == genericFFmpegMOVDecryptionStrategy && normalized.Key == "" {
+		return nil
+	}
+
+	return normalized
+}
+
+func normalizedDownloadDecryptionKey(info *DownloadDecryptionInfo, legacyKey string) string {
+	if normalized := normalizeDownloadDecryptionInfo(info, legacyKey); normalized != nil {
+		if normalized.Strategy == genericFFmpegMOVDecryptionStrategy {
+			return normalized.Key
+		}
+	}
+	return strings.TrimSpace(legacyKey)
+}
+
+type extensionProviderWrapper struct {
+	extension *loadedExtension
 	vm        *goja.Runtime
 }
 
-func NewExtensionProviderWrapper(ext *LoadedExtension) *ExtensionProviderWrapper {
-	return &ExtensionProviderWrapper{
+func newExtensionProviderWrapper(ext *loadedExtension) *extensionProviderWrapper {
+	return &extensionProviderWrapper{
 		extension: ext,
 		vm:        ext.VM,
 	}
 }
 
-func (p *ExtensionProviderWrapper) lockReadyVM() error {
+func (p *extensionProviderWrapper) lockReadyVM() error {
 	vm, err := p.extension.lockReadyVM()
 	if err != nil {
 		return err
@@ -134,7 +220,7 @@ func (p *ExtensionProviderWrapper) lockReadyVM() error {
 	return nil
 }
 
-func (p *ExtensionProviderWrapper) SearchTracks(query string, limit int) (*ExtSearchResult, error) {
+func (p *extensionProviderWrapper) SearchTracks(query string, limit int) (*ExtSearchResult, error) {
 	if !p.extension.Manifest.IsMetadataProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a metadata provider", p.extension.ID)
 	}
@@ -194,7 +280,7 @@ func (p *ExtensionProviderWrapper) SearchTracks(query string, limit int) (*ExtSe
 	return &searchResult, nil
 }
 
-func (p *ExtensionProviderWrapper) GetTrack(trackID string) (*ExtTrackMetadata, error) {
+func (p *extensionProviderWrapper) GetTrack(trackID string) (*ExtTrackMetadata, error) {
 	if !p.extension.Manifest.IsMetadataProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a metadata provider", p.extension.ID)
 	}
@@ -243,7 +329,7 @@ func (p *ExtensionProviderWrapper) GetTrack(trackID string) (*ExtTrackMetadata,
 	return &track, nil
 }
 
-func (p *ExtensionProviderWrapper) GetAlbum(albumID string) (*ExtAlbumMetadata, error) {
+func (p *extensionProviderWrapper) GetAlbum(albumID string) (*ExtAlbumMetadata, error) {
 	if !p.extension.Manifest.IsMetadataProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a metadata provider", p.extension.ID)
 	}
@@ -295,7 +381,7 @@ func (p *ExtensionProviderWrapper) GetAlbum(albumID string) (*ExtAlbumMetadata,
 	return &album, nil
 }
 
-func (p *ExtensionProviderWrapper) GetArtist(artistID string) (*ExtArtistMetadata, error) {
+func (p *extensionProviderWrapper) GetArtist(artistID string) (*ExtArtistMetadata, error) {
 	if !p.extension.Manifest.IsMetadataProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a metadata provider", p.extension.ID)
 	}
@@ -350,7 +436,7 @@ func (p *ExtensionProviderWrapper) GetArtist(artistID string) (*ExtArtistMetadat
 	return &artist, nil
 }
 
-func (p *ExtensionProviderWrapper) EnrichTrack(track *ExtTrackMetadata) (*ExtTrackMetadata, error) {
+func (p *extensionProviderWrapper) EnrichTrack(track *ExtTrackMetadata) (*ExtTrackMetadata, error) {
 	if !p.extension.Manifest.IsMetadataProvider() {
 		return track, nil
 	}
@@ -412,7 +498,7 @@ func (p *ExtensionProviderWrapper) EnrichTrack(track *ExtTrackMetadata) (*ExtTra
 	return &enrichedTrack, nil
 }
 
-func (p *ExtensionProviderWrapper) CheckAvailability(isrc, trackName, artistName, spotifyID, deezerID string) (*ExtAvailabilityResult, error) {
+func (p *extensionProviderWrapper) CheckAvailability(isrc, trackName, artistName, spotifyID, deezerID string) (*ExtAvailabilityResult, error) {
 	if !p.extension.Manifest.IsDownloadProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a download provider", p.extension.ID)
 	}
@@ -460,7 +546,7 @@ func (p *ExtensionProviderWrapper) CheckAvailability(isrc, trackName, artistName
 	return &availability, nil
 }
 
-func (p *ExtensionProviderWrapper) GetDownloadURL(trackID, quality string) (*ExtDownloadURLResult, error) {
+func (p *extensionProviderWrapper) GetDownloadURL(trackID, quality string) (*ExtDownloadURLResult, error) {
 	if !p.extension.Manifest.IsDownloadProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a download provider", p.extension.ID)
 	}
@@ -510,7 +596,7 @@ func (p *ExtensionProviderWrapper) GetDownloadURL(trackID, quality string) (*Ext
 
 const ExtDownloadTimeout = DownloadTimeout
 
-func (p *ExtensionProviderWrapper) Download(trackID, quality, outputPath, itemID string, onProgress func(percent int)) (*ExtDownloadResult, error) {
+func (p *extensionProviderWrapper) Download(trackID, quality, outputPath, itemID string, onProgress func(percent int)) (*ExtDownloadResult, error) {
 	if !p.extension.Manifest.IsDownloadProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a download provider", p.extension.ID)
 	}
@@ -597,44 +683,52 @@ func (p *ExtensionProviderWrapper) Download(trackID, quality, outputPath, itemID
 			ErrorType:    "internal_error",
 		}, nil
 	}
+	downloadResult.Decryption = normalizeDownloadDecryptionInfo(
+		downloadResult.Decryption,
+		downloadResult.DecryptionKey,
+	)
+	downloadResult.DecryptionKey = normalizedDownloadDecryptionKey(
+		downloadResult.Decryption,
+		downloadResult.DecryptionKey,
+	)
 
 	return &downloadResult, nil
 }
 
-func (m *ExtensionManager) GetMetadataProviders() []*ExtensionProviderWrapper {
+func (m *extensionManager) GetMetadataProviders() []*extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	var providers []*ExtensionProviderWrapper
+	var providers []*extensionProviderWrapper
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.IsMetadataProvider() && ext.Error == "" {
-			providers = append(providers, NewExtensionProviderWrapper(ext))
+			providers = append(providers, newExtensionProviderWrapper(ext))
 		}
 	}
 	return providers
 }
 
-func (m *ExtensionManager) GetDownloadProviders() []*ExtensionProviderWrapper {
+func (m *extensionManager) GetDownloadProviders() []*extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	var providers []*ExtensionProviderWrapper
+	var providers []*extensionProviderWrapper
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.IsDownloadProvider() && ext.Error == "" {
-			providers = append(providers, NewExtensionProviderWrapper(ext))
+			providers = append(providers, newExtensionProviderWrapper(ext))
 		}
 	}
 	return providers
 }
 
-func (m *ExtensionManager) SearchTracksWithExtensions(query string, limit int) ([]ExtTrackMetadata, error) {
+func (m *extensionManager) SearchTracksWithExtensions(query string, limit int) ([]ExtTrackMetadata, error) {
 	providers := m.GetMetadataProviders()
 	if len(providers) == 0 {
 		return nil, nil
 	}
 
-	providerByID := make(map[string]*ExtensionProviderWrapper, len(providers))
-	orderedProviders := make([]*ExtensionProviderWrapper, 0, len(providers))
+	providerByID := make(map[string]*extensionProviderWrapper, len(providers))
+	orderedProviders := make([]*extensionProviderWrapper, 0, len(providers))
 	for _, provider := range providers {
 		providerByID[provider.extension.ID] = provider
 	}
@@ -673,6 +767,9 @@ func (m *ExtensionManager) SearchTracksWithExtensions(query string, limit int) (
 var providerPriority []string
 var providerPriorityMu sync.RWMutex
 
+var extensionFallbackProviderIDs []string
+var extensionFallbackProviderIDsMu sync.RWMutex
+
 var metadataProviderPriority []string
 var metadataProviderPriorityMu sync.RWMutex
 
@@ -681,8 +778,8 @@ var searchBuiltInMetadataTracksFunc = searchBuiltInMetadataTracks
 func SetProviderPriority(providerIDs []string) {
 	providerPriorityMu.Lock()
 	defer providerPriorityMu.Unlock()
-	providerPriority = providerIDs
-	GoLog("[Extension] Download provider priority set: %v\n", providerIDs)
+	providerPriority = sanitizeDownloadProviderPriority(providerIDs)
+	GoLog("[Extension] Download provider priority set: %v\n", providerPriority)
 }
 
 func GetProviderPriority() []string {
@@ -690,7 +787,7 @@ func GetProviderPriority() []string {
 	defer providerPriorityMu.RUnlock()
 
 	if len(providerPriority) == 0 {
-		return []string{"tidal", "qobuz", "deezer"}
+		return []string{"tidal", "qobuz"}
 	}
 
 	result := make([]string, len(providerPriority))
@@ -698,6 +795,102 @@ func GetProviderPriority() []string {
 	return result
 }
 
+func sanitizeDownloadProviderPriority(providerIDs []string) []string {
+	sanitized := make([]string, 0, len(providerIDs)+2)
+	seen := map[string]struct{}{}
+
+	for _, providerID := range providerIDs {
+		providerID = strings.TrimSpace(providerID)
+		if providerID == "" {
+			continue
+		}
+
+		normalizedBuiltIn := strings.ToLower(providerID)
+		if normalizedBuiltIn == "deezer" {
+			continue
+		}
+		if isBuiltInDownloadProvider(normalizedBuiltIn) {
+			providerID = normalizedBuiltIn
+		}
+
+		seenKey := strings.ToLower(providerID)
+		if _, exists := seen[seenKey]; exists {
+			continue
+		}
+		seen[seenKey] = struct{}{}
+		sanitized = append(sanitized, providerID)
+	}
+
+	for _, providerID := range []string{"tidal", "qobuz"} {
+		if _, exists := seen[providerID]; exists {
+			continue
+		}
+		seen[providerID] = struct{}{}
+		sanitized = append(sanitized, providerID)
+	}
+
+	return sanitized
+}
+
+func SetExtensionFallbackProviderIDs(providerIDs []string) {
+	extensionFallbackProviderIDsMu.Lock()
+	defer extensionFallbackProviderIDsMu.Unlock()
+
+	if providerIDs == nil {
+		extensionFallbackProviderIDs = nil
+		GoLog("[Extension] Extension fallback providers reset to default (all enabled download extensions)\n")
+		return
+	}
+
+	sanitized := make([]string, 0, len(providerIDs))
+	seen := map[string]struct{}{}
+	for _, providerID := range providerIDs {
+		providerID = strings.TrimSpace(providerID)
+		if providerID == "" || isBuiltInDownloadProvider(strings.ToLower(providerID)) {
+			continue
+		}
+		if _, exists := seen[providerID]; exists {
+			continue
+		}
+		seen[providerID] = struct{}{}
+		sanitized = append(sanitized, providerID)
+	}
+
+	extensionFallbackProviderIDs = sanitized
+	GoLog("[Extension] Extension fallback providers set: %v\n", sanitized)
+}
+
+func GetExtensionFallbackProviderIDs() []string {
+	extensionFallbackProviderIDsMu.RLock()
+	defer extensionFallbackProviderIDsMu.RUnlock()
+
+	if extensionFallbackProviderIDs == nil {
+		return nil
+	}
+
+	result := make([]string, len(extensionFallbackProviderIDs))
+	copy(result, extensionFallbackProviderIDs)
+	return result
+}
+
+func isExtensionFallbackAllowed(providerID string) bool {
+	if isBuiltInDownloadProvider(strings.ToLower(providerID)) {
+		return true
+	}
+
+	allowed := GetExtensionFallbackProviderIDs()
+	if allowed == nil {
+		return true
+	}
+
+	for _, allowedProviderID := range allowed {
+		if allowedProviderID == providerID {
+			return true
+		}
+	}
+	return false
+}
+
 func SetMetadataProviderPriority(providerIDs []string) {
 	metadataProviderPriorityMu.Lock()
 	defer metadataProviderPriorityMu.Unlock()
@@ -749,6 +942,15 @@ func isBuiltInProvider(providerID string) bool {
 	}
 }
 
+func isBuiltInDownloadProvider(providerID string) bool {
+	switch providerID {
+	case "tidal", "qobuz":
+		return true
+	default:
+		return false
+	}
+}
+
 func normalizeBuiltInMetadataTrack(track TrackMetadata, providerID string) ExtTrackMetadata {
 	deezerID := ""
 	tidalID := ""
@@ -775,7 +977,9 @@ func normalizeBuiltInMetadataTrack(track TrackMetadata, providerID string) ExtTr
 		Images:      track.Images,
 		ReleaseDate: track.ReleaseDate,
 		TrackNumber: track.TrackNumber,
+		TotalTracks: track.TotalTracks,
 		DiscNumber:  track.DiscNumber,
+		TotalDiscs:  track.TotalDiscs,
 		ISRC:        track.ISRC,
 		ProviderID:  providerID,
 		SpotifyID:   prefixedID,
@@ -783,6 +987,7 @@ func normalizeBuiltInMetadataTrack(track TrackMetadata, providerID string) ExtTr
 		TidalID:     tidalID,
 		QobuzID:     qobuzID,
 		AlbumType:   track.AlbumType,
+		Composer:    track.Composer,
 	}
 }
 
@@ -824,13 +1029,13 @@ func searchBuiltInMetadataTracks(providerID, query string, limit int) ([]ExtTrac
 	}
 }
 
-func (m *ExtensionManager) SearchTracksWithMetadataProviders(query string, limit int, includeExtensions bool) ([]ExtTrackMetadata, error) {
+func (m *extensionManager) SearchTracksWithMetadataProviders(query string, limit int, includeExtensions bool) ([]ExtTrackMetadata, error) {
 	priority := GetMetadataProviderPriority()
 	if limit <= 0 {
 		limit = 20
 	}
 
-	extensionProviders := make(map[string]*ExtensionProviderWrapper)
+	extensionProviders := make(map[string]*extensionProviderWrapper)
 	if includeExtensions {
 		for _, provider := range m.GetMetadataProviders() {
 			extensionProviders[provider.extension.ID] = provider
@@ -910,7 +1115,7 @@ func (m *ExtensionManager) SearchTracksWithMetadataProviders(query string, limit
 
 func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, error) {
 	priority := GetProviderPriority()
-	extManager := GetExtensionManager()
+	extManager := getExtensionManager()
 	strictMode := !req.UseFallback
 	selectedProvider := strings.TrimSpace(req.Service)
 
@@ -924,7 +1129,7 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 		}
 	}
 
-	if !strictMode && req.Service != "" && isBuiltInProvider(strings.ToLower(req.Service)) {
+	if !strictMode && req.Service != "" && isBuiltInDownloadProvider(strings.ToLower(req.Service)) {
 		GoLog("[DownloadWithExtensionFallback] User selected service: %s, prioritizing it first\n", req.Service)
 		newPriority := []string{req.Service}
 		for _, p := range priority {
@@ -934,7 +1139,7 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 		}
 		priority = newPriority
 		GoLog("[DownloadWithExtensionFallback] New priority order: %v\n", priority)
-	} else if !strictMode && req.Service != "" && !isBuiltInProvider(strings.ToLower(req.Service)) {
+	} else if !strictMode && req.Service != "" && !isBuiltInDownloadProvider(strings.ToLower(req.Service)) {
 		found := false
 		for _, p := range priority {
 			if strings.EqualFold(p, req.Service) {
@@ -965,7 +1170,7 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 		if err == nil && ext.Enabled && ext.Error == "" && ext.Manifest.IsMetadataProvider() {
 			GoLog("[DownloadWithExtensionFallback] Enriching track from extension '%s'...\n", req.Source)
 
-			provider := NewExtensionProviderWrapper(ext)
+			provider := newExtensionProviderWrapper(ext)
 			trackMeta := &ExtTrackMetadata{
 				ID:          req.SpotifyID,
 				Name:        req.TrackName,
@@ -975,8 +1180,11 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 				ISRC:        req.ISRC,
 				ReleaseDate: req.ReleaseDate,
 				TrackNumber: req.TrackNumber,
+				TotalTracks: req.TotalTracks,
 				DiscNumber:  req.DiscNumber,
+				TotalDiscs:  req.TotalDiscs,
 				ProviderID:  req.Source,
+				Composer:    req.Composer,
 			}
 
 			enrichedTrack, err := provider.EnrichTrack(trackMeta)
@@ -1041,10 +1249,22 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 					GoLog("[DownloadWithExtensionFallback] TrackNumber from enrichment: %d\n", enrichedTrack.TrackNumber)
 					req.TrackNumber = enrichedTrack.TrackNumber
 				}
+				if enrichedTrack.TotalTracks > 0 && req.TotalTracks == 0 {
+					GoLog("[DownloadWithExtensionFallback] TotalTracks from enrichment: %d\n", enrichedTrack.TotalTracks)
+					req.TotalTracks = enrichedTrack.TotalTracks
+				}
 				if enrichedTrack.DiscNumber > 0 && req.DiscNumber == 0 {
 					GoLog("[DownloadWithExtensionFallback] DiscNumber from enrichment: %d\n", enrichedTrack.DiscNumber)
 					req.DiscNumber = enrichedTrack.DiscNumber
 				}
+				if enrichedTrack.TotalDiscs > 0 && req.TotalDiscs == 0 {
+					GoLog("[DownloadWithExtensionFallback] TotalDiscs from enrichment: %d\n", enrichedTrack.TotalDiscs)
+					req.TotalDiscs = enrichedTrack.TotalDiscs
+				}
+				if enrichedTrack.Composer != "" && req.Composer == "" {
+					GoLog("[DownloadWithExtensionFallback] Composer from enrichment: %s\n", enrichedTrack.Composer)
+					req.Composer = enrichedTrack.Composer
+				}
 			}
 		}
 	}
@@ -1077,9 +1297,18 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 			if track.TrackNumber > 0 && req.TrackNumber == 0 {
 				req.TrackNumber = track.TrackNumber
 			}
+			if track.TotalTracks > 0 && req.TotalTracks == 0 {
+				req.TotalTracks = track.TotalTracks
+			}
 			if track.DiscNumber > 0 && req.DiscNumber == 0 {
 				req.DiscNumber = track.DiscNumber
 			}
+			if track.TotalDiscs > 0 && req.TotalDiscs == 0 {
+				req.TotalDiscs = track.TotalDiscs
+			}
+			if track.Composer != "" && req.Composer == "" {
+				req.Composer = track.Composer
+			}
 			if track.CoverURL != "" && req.CoverURL == "" {
 				req.CoverURL = track.CoverURL
 			}
@@ -1125,7 +1354,7 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 		if err == nil && ext.Enabled && ext.Error == "" && ext.Manifest.IsDownloadProvider() {
 			skipBuiltIn = ext.Manifest.SkipBuiltInFallback
 
-			provider := NewExtensionProviderWrapper(ext)
+			provider := newExtensionProviderWrapper(ext)
 
 			trackID := req.SpotifyID
 
@@ -1168,14 +1397,17 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 					Label:            req.Label,
 					Copyright:        req.Copyright,
 					DecryptionKey:    result.DecryptionKey,
+					Decryption:       normalizeDownloadDecryptionInfo(result.Decryption, result.DecryptionKey),
 				}
 
-				if req.EmbedMetadata && (req.Genre != "" || req.Label != "") {
+				if req.EmbedMetadata && (req.Genre != "" || req.Label != "") && canEmbedGenreLabel(result.FilePath) {
 					if err := EmbedGenreLabel(result.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 req.EmbedMetadata && (req.Genre != "" || req.Label != "") {
+					GoLog("[DownloadWithExtensionFallback] Skipping genre/label embed for non-local output path: %q\n", result.FilePath)
 				}
 
 				if ext.Manifest.SkipMetadataEnrichment {
@@ -1273,14 +1505,19 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 			continue
 		}
 
-		if skipBuiltIn && isBuiltInProvider(providerIDNormalized) {
+		if skipBuiltIn && isBuiltInDownloadProvider(providerIDNormalized) {
 			GoLog("[DownloadWithExtensionFallback] Skipping built-in provider %s (skipBuiltInFallback)\n", providerID)
 			continue
 		}
 
+		if !isBuiltInDownloadProvider(providerIDNormalized) && !isExtensionFallbackAllowed(providerID) {
+			GoLog("[DownloadWithExtensionFallback] Skipping extension provider %s (not enabled for fallback)\n", providerID)
+			continue
+		}
+
 		GoLog("[DownloadWithExtensionFallback] Trying provider: %s\n", providerID)
 
-		if isBuiltInProvider(providerIDNormalized) {
+		if isBuiltInDownloadProvider(providerIDNormalized) {
 			if (req.Genre == "" || req.Label == "" || req.Copyright == "") &&
 				req.ISRC != "" {
 				GoLog("[DownloadWithExtensionFallback] Enriching extended metadata from Deezer for ISRC: %s\n", req.ISRC)
@@ -1346,7 +1583,7 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 				continue
 			}
 
-			provider := NewExtensionProviderWrapper(ext)
+			provider := newExtensionProviderWrapper(ext)
 
 			availability, err := provider.CheckAvailability(req.ISRC, req.TrackName, req.ArtistName, req.SpotifyID, req.DeezerID)
 			if err != nil || !availability.Available {
@@ -1394,14 +1631,17 @@ func DownloadWithExtensionFallback(req DownloadRequest) (*DownloadResponse, erro
 					Label:            req.Label,
 					Copyright:        req.Copyright,
 					DecryptionKey:    result.DecryptionKey,
+					Decryption:       normalizeDownloadDecryptionInfo(result.Decryption, result.DecryptionKey),
 				}
 
-				if req.EmbedMetadata && (req.Genre != "" || req.Label != "") {
+				if req.EmbedMetadata && (req.Genre != "" || req.Label != "") && canEmbedGenreLabel(result.FilePath) {
 					if err := EmbedGenreLabel(result.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 req.EmbedMetadata && (req.Genre != "" || req.Label != "") {
+					GoLog("[DownloadWithExtensionFallback] Skipping genre/label embed for non-local output path: %q\n", result.FilePath)
 				}
 
 				if ext.Manifest.SkipMetadataEnrichment {
@@ -1534,24 +1774,6 @@ func tryBuiltInProvider(providerID string, req DownloadRequest) (*DownloadRespon
 			}
 		}
 		err = qobuzErr
-	case "deezer":
-		deezerResult, deezerErr := downloadFromDeezer(req)
-		if deezerErr == nil {
-			result = DownloadResult{
-				FilePath:    deezerResult.FilePath,
-				BitDepth:    deezerResult.BitDepth,
-				SampleRate:  deezerResult.SampleRate,
-				Title:       deezerResult.Title,
-				Artist:      deezerResult.Artist,
-				Album:       deezerResult.Album,
-				ReleaseDate: deezerResult.ReleaseDate,
-				TrackNumber: deezerResult.TrackNumber,
-				DiscNumber:  deezerResult.DiscNumber,
-				ISRC:        deezerResult.ISRC,
-				LyricsLRC:   deezerResult.LyricsLRC,
-			}
-		}
-		err = deezerErr
 	default:
 		return nil, fmt.Errorf("unknown built-in provider: %s", providerID)
 	}
@@ -1579,6 +1801,7 @@ func tryBuiltInProvider(providerID string, req DownloadRequest) (*DownloadRespon
 		Copyright:        req.Copyright,
 		LyricsLRC:        result.LyricsLRC,
 		DecryptionKey:    result.DecryptionKey,
+		Decryption:       normalizeDownloadDecryptionInfo(result.Decryption, result.DecryptionKey),
 	}, nil
 }
 
@@ -1594,12 +1817,15 @@ func buildOutputPath(req DownloadRequest) string {
 		"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,
 	}
 
 	filename := buildFilenameFromTemplate(req.FilenameFormat, metadata)
@@ -1617,19 +1843,24 @@ func buildOutputPath(req DownloadRequest) string {
 	outputDir := req.OutputDir
 	if strings.TrimSpace(outputDir) == "" {
 		outputDir = filepath.Join(os.TempDir(), "spotiflac-downloads")
-		os.MkdirAll(outputDir, 0755)
-		AddAllowedDownloadDir(outputDir)
 	}
+	os.MkdirAll(outputDir, 0755)
+	AddAllowedDownloadDir(outputDir)
 
 	return filepath.Join(outputDir, filename+ext)
 }
 
-func buildOutputPathForExtension(req DownloadRequest, ext *LoadedExtension) string {
+func buildOutputPathForExtension(req DownloadRequest, ext *loadedExtension) string {
 	if strings.TrimSpace(req.OutputPath) != "" {
-		return strings.TrimSpace(req.OutputPath)
+		outputPath := strings.TrimSpace(req.OutputPath)
+		AddAllowedDownloadDir(filepath.Dir(outputPath))
+		return outputPath
 	}
 
-	if strings.TrimSpace(req.OutputDir) != "" {
+	// SAF downloads hand extensions a detached output FD owned by the host.
+	// Extensions still need a real local temp file so Android can copy it into
+	// the target document after provider-specific post-processing completes.
+	if !isFDOutput(req.OutputFD) && strings.TrimSpace(req.OutputDir) != "" {
 		return buildOutputPath(req)
 	}
 
@@ -1644,12 +1875,15 @@ func buildOutputPathForExtension(req DownloadRequest, ext *LoadedExtension) stri
 		"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,
 	}
 
 	filename := buildFilenameFromTemplate(req.FilenameFormat, metadata)
@@ -1667,7 +1901,19 @@ func buildOutputPathForExtension(req DownloadRequest, ext *LoadedExtension) stri
 	return filepath.Join(tempDir, filename+outputExt)
 }
 
-func (p *ExtensionProviderWrapper) CustomSearch(query string, options map[string]interface{}) ([]ExtTrackMetadata, error) {
+func canEmbedGenreLabel(filePath string) bool {
+	path := strings.TrimSpace(filePath)
+	if path == "" || strings.HasPrefix(path, "content://") || strings.HasPrefix(path, "/proc/self/fd/") {
+		return false
+	}
+	if !filepath.IsAbs(path) {
+		return false
+	}
+	info, err := os.Stat(path)
+	return err == nil && !info.IsDir() && info.Size() > 0
+}
+
+func (p *extensionProviderWrapper) CustomSearch(query string, options map[string]interface{}) ([]ExtTrackMetadata, error) {
 	if !p.extension.Manifest.HasCustomSearch() {
 		return nil, fmt.Errorf("extension '%s' does not support custom search", p.extension.ID)
 	}
@@ -1749,7 +1995,7 @@ type ExtURLHandleResult struct {
 	CoverURL string             `json:"cover_url,omitempty"`
 }
 
-func (p *ExtensionProviderWrapper) HandleURL(url string) (*ExtURLHandleResult, error) {
+func (p *extensionProviderWrapper) HandleURL(url string) (*ExtURLHandleResult, error) {
 	if !p.extension.Manifest.HasURLHandler() {
 		return nil, fmt.Errorf("extension '%s' does not support URL handling", p.extension.ID)
 	}
@@ -1835,7 +2081,7 @@ type MatchTrackResult struct {
 	Reason     string  `json:"reason,omitempty"`
 }
 
-func (p *ExtensionProviderWrapper) MatchTrack(sourceTrack map[string]interface{}, candidates []map[string]interface{}) (*MatchTrackResult, error) {
+func (p *extensionProviderWrapper) MatchTrack(sourceTrack map[string]interface{}, candidates []map[string]interface{}) (*MatchTrackResult, error) {
 	if !p.extension.Manifest.HasCustomMatching() {
 		return nil, fmt.Errorf("extension '%s' does not support custom matching", p.extension.ID)
 	}
@@ -1906,7 +2152,7 @@ type PostProcessInput struct {
 
 const PostProcessTimeout = 2 * time.Minute
 
-func (p *ExtensionProviderWrapper) PostProcess(filePath string, metadata map[string]interface{}, hookID string) (*PostProcessResult, error) {
+func (p *extensionProviderWrapper) PostProcess(filePath string, metadata map[string]interface{}, hookID string) (*PostProcessResult, error) {
 	if !p.extension.Manifest.HasPostProcessing() {
 		return nil, fmt.Errorf("extension '%s' does not support post-processing", p.extension.ID)
 	}
@@ -1969,7 +2215,7 @@ func (p *ExtensionProviderWrapper) PostProcess(filePath string, metadata map[str
 	return &postResult, nil
 }
 
-func (p *ExtensionProviderWrapper) PostProcessV2(input PostProcessInput, metadata map[string]interface{}, hookID string) (*PostProcessResult, error) {
+func (p *extensionProviderWrapper) PostProcessV2(input PostProcessInput, metadata map[string]interface{}, hookID string) (*PostProcessResult, error) {
 	if !p.extension.Manifest.HasPostProcessing() {
 		return nil, fmt.Errorf("extension '%s' does not support post-processing", p.extension.ID)
 	}
@@ -2039,39 +2285,39 @@ func (p *ExtensionProviderWrapper) PostProcessV2(input PostProcessInput, metadat
 	return &postResult, nil
 }
 
-func (m *ExtensionManager) GetSearchProviders() []*ExtensionProviderWrapper {
+func (m *extensionManager) GetSearchProviders() []*extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	var providers []*ExtensionProviderWrapper
+	var providers []*extensionProviderWrapper
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.HasCustomSearch() && ext.Error == "" {
-			providers = append(providers, NewExtensionProviderWrapper(ext))
+			providers = append(providers, newExtensionProviderWrapper(ext))
 		}
 	}
 	return providers
 }
 
-func (m *ExtensionManager) GetURLHandlers() []*ExtensionProviderWrapper {
+func (m *extensionManager) GetURLHandlers() []*extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	var providers []*ExtensionProviderWrapper
+	var providers []*extensionProviderWrapper
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.HasURLHandler() && ext.Error == "" {
-			providers = append(providers, NewExtensionProviderWrapper(ext))
+			providers = append(providers, newExtensionProviderWrapper(ext))
 		}
 	}
 	return providers
 }
 
-func (m *ExtensionManager) FindURLHandler(url string) *ExtensionProviderWrapper {
+func (m *extensionManager) FindURLHandler(url string) *extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.MatchesURL(url) && ext.Error == "" {
-			return NewExtensionProviderWrapper(ext)
+			return newExtensionProviderWrapper(ext)
 		}
 	}
 	return nil
@@ -2082,7 +2328,7 @@ type ExtURLHandleResultWithExtID struct {
 	ExtensionID string
 }
 
-func (m *ExtensionManager) HandleURLWithExtension(url string) (*ExtURLHandleResultWithExtID, error) {
+func (m *extensionManager) HandleURLWithExtension(url string) (*ExtURLHandleResultWithExtID, error) {
 	handler := m.FindURLHandler(url)
 	if handler == nil {
 		return nil, fmt.Errorf("no extension found to handle URL: %s", url)
@@ -2102,20 +2348,20 @@ func (m *ExtensionManager) HandleURLWithExtension(url string) (*ExtURLHandleResu
 	}, nil
 }
 
-func (m *ExtensionManager) GetPostProcessingProviders() []*ExtensionProviderWrapper {
+func (m *extensionManager) GetPostProcessingProviders() []*extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	var providers []*ExtensionProviderWrapper
+	var providers []*extensionProviderWrapper
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.HasPostProcessing() && ext.Error == "" {
-			providers = append(providers, NewExtensionProviderWrapper(ext))
+			providers = append(providers, newExtensionProviderWrapper(ext))
 		}
 	}
 	return providers
 }
 
-func (m *ExtensionManager) RunPostProcessing(filePath string, metadata map[string]interface{}) (*PostProcessResult, error) {
+func (m *extensionManager) RunPostProcessing(filePath string, metadata map[string]interface{}) (*PostProcessResult, error) {
 	providers := m.GetPostProcessingProviders()
 	if len(providers) == 0 {
 		return &PostProcessResult{Success: true, NewFilePath: filePath}, nil
@@ -2160,7 +2406,7 @@ func (m *ExtensionManager) RunPostProcessing(filePath string, metadata map[strin
 	return &PostProcessResult{Success: true, NewFilePath: currentPath}, nil
 }
 
-func (m *ExtensionManager) RunPostProcessingV2(input PostProcessInput, metadata map[string]interface{}) (*PostProcessResult, error) {
+func (m *extensionManager) RunPostProcessingV2(input PostProcessInput, metadata map[string]interface{}) (*PostProcessResult, error) {
 	providers := m.GetPostProcessingProviders()
 	if len(providers) == 0 {
 		return &PostProcessResult{Success: true, NewFilePath: input.Path, NewFileURI: input.URI}, nil
@@ -2228,7 +2474,7 @@ type ExtLyricsLine struct {
 	EndTimeMs   int64  `json:"endTimeMs"`
 }
 
-func (p *ExtensionProviderWrapper) FetchLyrics(trackName, artistName, albumName string, durationSec float64) (*LyricsResponse, error) {
+func (p *extensionProviderWrapper) FetchLyrics(trackName, artistName, albumName string, durationSec float64) (*LyricsResponse, error) {
 	if !p.extension.Manifest.IsLyricsProvider() {
 		return nil, fmt.Errorf("extension '%s' is not a lyrics provider", p.extension.ID)
 	}
@@ -2326,14 +2572,14 @@ func (p *ExtensionProviderWrapper) FetchLyrics(trackName, artistName, albumName
 	return response, nil
 }
 
-func (m *ExtensionManager) GetLyricsProviders() []*ExtensionProviderWrapper {
+func (m *extensionManager) GetLyricsProviders() []*extensionProviderWrapper {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
-	var providers []*ExtensionProviderWrapper
+	var providers []*extensionProviderWrapper
 	for _, ext := range m.extensions {
 		if ext.Enabled && ext.Manifest.IsLyricsProvider() && ext.Error == "" {
-			providers = append(providers, NewExtensionProviderWrapper(ext))
+			providers = append(providers, newExtensionProviderWrapper(ext))
 		}
 	}
 

go_backend/extension_providers_test.go

@@ -1,6 +1,10 @@
 package gobackend
 
-import "testing"
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
 
 func TestSetMetadataProviderPriorityAddsBuiltIns(t *testing.T) {
 	original := GetMetadataProviderPriority()
@@ -19,6 +23,183 @@ func TestSetMetadataProviderPriorityAddsBuiltIns(t *testing.T) {
 	}
 }
 
+func TestSetExtensionFallbackProviderIDsSkipsBuiltInsAndDuplicates(t *testing.T) {
+	original := GetExtensionFallbackProviderIDs()
+	defer SetExtensionFallbackProviderIDs(original)
+
+	SetExtensionFallbackProviderIDs([]string{"ext-a", "tidal", "ext-a", " ext-b "})
+
+	got := GetExtensionFallbackProviderIDs()
+	want := []string{"ext-a", "ext-b"}
+	if len(got) != len(want) {
+		t.Fatalf("unexpected fallback provider length: got %v want %v", got, want)
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Fatalf("unexpected fallback provider at %d: got %v want %v", i, got, want)
+		}
+	}
+}
+
+func TestIsExtensionFallbackAllowedDefaultsToAllExtensions(t *testing.T) {
+	original := GetExtensionFallbackProviderIDs()
+	defer SetExtensionFallbackProviderIDs(original)
+
+	SetExtensionFallbackProviderIDs(nil)
+
+	if !isExtensionFallbackAllowed("custom-ext") {
+		t.Fatal("expected custom extension to be allowed when no fallback allowlist is configured")
+	}
+	if !isExtensionFallbackAllowed("qobuz") {
+		t.Fatal("expected built-in provider to remain allowed")
+	}
+}
+
+func TestIsExtensionFallbackAllowedRespectsAllowlist(t *testing.T) {
+	original := GetExtensionFallbackProviderIDs()
+	defer SetExtensionFallbackProviderIDs(original)
+
+	SetExtensionFallbackProviderIDs([]string{"allowed-ext"})
+
+	if !isExtensionFallbackAllowed("allowed-ext") {
+		t.Fatal("expected explicitly allowed extension to be permitted")
+	}
+	if isExtensionFallbackAllowed("blocked-ext") {
+		t.Fatal("expected extension outside allowlist to be blocked")
+	}
+	if isExtensionFallbackAllowed("deezer") {
+		t.Fatal("expected retired Deezer downloader to respect extension fallback allowlist")
+	}
+}
+
+func TestSetProviderPriorityRemovesRetiredDeezerDownloader(t *testing.T) {
+	original := GetProviderPriority()
+	defer SetProviderPriority(original)
+
+	SetProviderPriority([]string{"deezer", "qobuz", "custom-ext"})
+
+	got := GetProviderPriority()
+	want := []string{"qobuz", "custom-ext", "tidal"}
+	if len(got) != len(want) {
+		t.Fatalf("unexpected priority length: got %v want %v", got, want)
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Fatalf("unexpected priority at %d: got %v want %v", i, got, want)
+		}
+	}
+}
+
+func TestNormalizeDownloadDecryptionInfoPromotesLegacyKey(t *testing.T) {
+	normalized := normalizeDownloadDecryptionInfo(nil, " 001122 ")
+	if normalized == nil {
+		t.Fatal("expected legacy decryption key to produce normalized descriptor")
+	}
+	if normalized.Strategy != genericFFmpegMOVDecryptionStrategy {
+		t.Fatalf("strategy = %q", normalized.Strategy)
+	}
+	if normalized.Key != "001122" {
+		t.Fatalf("key = %q", normalized.Key)
+	}
+	if normalized.InputFormat != "mov" {
+		t.Fatalf("input format = %q", normalized.InputFormat)
+	}
+}
+
+func TestNormalizeDownloadDecryptionInfoCanonicalizesMovAliases(t *testing.T) {
+	normalized := normalizeDownloadDecryptionInfo(&DownloadDecryptionInfo{
+		Strategy:    "mp4_decryption_key",
+		Key:         "abcd",
+		InputFormat: "",
+	}, "")
+	if normalized == nil {
+		t.Fatal("expected descriptor to remain available")
+	}
+	if normalized.Strategy != genericFFmpegMOVDecryptionStrategy {
+		t.Fatalf("strategy = %q", normalized.Strategy)
+	}
+	if normalized.InputFormat != "mov" {
+		t.Fatalf("input format = %q", normalized.InputFormat)
+	}
+}
+
+func TestBuildOutputPathAddsExplicitOutputDirToAllowedDirs(t *testing.T) {
+	SetAllowedDownloadDirs(nil)
+
+	outputDir := t.TempDir()
+	outputPath := buildOutputPath(DownloadRequest{
+		TrackName:      "Song",
+		ArtistName:     "Artist",
+		OutputDir:      outputDir,
+		OutputExt:      ".flac",
+		FilenameFormat: "",
+	})
+
+	if !isPathInAllowedDirs(outputPath) {
+		t.Fatalf("expected output path %q to be allowed", outputPath)
+	}
+}
+
+func TestBuildOutputPathForExtensionAddsExplicitOutputPathDirToAllowedDirs(t *testing.T) {
+	SetAllowedDownloadDirs(nil)
+
+	outputDir := t.TempDir()
+	outputPath := filepath.Join(outputDir, "custom.flac")
+	ext := &loadedExtension{DataDir: t.TempDir()}
+
+	resolved := buildOutputPathForExtension(DownloadRequest{
+		OutputPath: outputPath,
+	}, ext)
+
+	if resolved != outputPath {
+		t.Fatalf("resolved output path = %q", resolved)
+	}
+	if !isPathInAllowedDirs(outputPath) {
+		t.Fatalf("expected output path %q to be allowed", outputPath)
+	}
+}
+
+func TestBuildOutputPathForExtensionUsesTempDirForFDOutput(t *testing.T) {
+	SetAllowedDownloadDirs(nil)
+
+	ext := &loadedExtension{DataDir: t.TempDir()}
+	resolved := buildOutputPathForExtension(DownloadRequest{
+		TrackName:  "Song",
+		ArtistName: "Artist",
+		OutputDir:  filepath.Join("Artist", "Album"),
+		OutputFD:   123,
+		OutputExt:  ".flac",
+	}, ext)
+
+	expectedBase := filepath.Join(ext.DataDir, "downloads")
+	if !isPathWithinBase(expectedBase, resolved) {
+		t.Fatalf("expected SAF extension output under %q, got %q", expectedBase, resolved)
+	}
+	if !isPathInAllowedDirs(resolved) {
+		t.Fatalf("expected resolved output path %q to be allowed", resolved)
+	}
+}
+
+func TestCanEmbedGenreLabelRequiresExistingAbsoluteLocalFile(t *testing.T) {
+	tempFile := filepath.Join(t.TempDir(), "track.flac")
+	if err := os.WriteFile(tempFile, []byte("fLaC"), 0644); err != nil {
+		t.Fatalf("failed to create temp file: %v", err)
+	}
+
+	if canEmbedGenreLabel("relative.flac") {
+		t.Fatal("expected relative path to be rejected")
+	}
+	if canEmbedGenreLabel("content://example") {
+		t.Fatal("expected content URI to be rejected")
+	}
+	if canEmbedGenreLabel(filepath.Join(t.TempDir(), "missing.flac")) {
+		t.Fatal("expected missing file to be rejected")
+	}
+	if !canEmbedGenreLabel(tempFile) {
+		t.Fatalf("expected existing absolute file %q to be accepted", tempFile)
+	}
+}
+
 func TestSearchTracksWithMetadataProvidersUsesPriorityAndDedupes(t *testing.T) {
 	originalPriority := GetMetadataProviderPriority()
 	originalSearch := searchBuiltInMetadataTracksFunc
@@ -51,7 +232,7 @@ func TestSearchTracksWithMetadataProvidersUsesPriorityAndDedupes(t *testing.T) {
 		}
 	}
 
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	tracks, err := manager.SearchTracksWithMetadataProviders("query", 3, false)
 	if err != nil {
 		t.Fatalf("SearchTracksWithMetadataProviders returned error: %v", err)

go_backend/extension_runtime.go

@@ -80,7 +80,7 @@ func SetExtensionTokens(extensionID string, accessToken, refreshToken string, ex
 	state.IsAuthenticated = accessToken != ""
 }
 
-type ExtensionRuntime struct {
+type extensionRuntime struct {
 	extensionID    string
 	manifest       *ExtensionManifest
 	settings       map[string]interface{}
@@ -123,10 +123,10 @@ var (
 	privateIPCacheMu sync.RWMutex
 )
 
-func NewExtensionRuntime(ext *LoadedExtension) *ExtensionRuntime {
+func newExtensionRuntime(ext *loadedExtension) *extensionRuntime {
 	jar, _ := newSimpleCookieJar()
 
-	runtime := &ExtensionRuntime{
+	runtime := &extensionRuntime{
 		extensionID:       ext.ID,
 		manifest:          ext.Manifest,
 		settings:          make(map[string]interface{}),
@@ -142,25 +142,25 @@ func NewExtensionRuntime(ext *LoadedExtension) *ExtensionRuntime {
 	return runtime
 }
 
-func (r *ExtensionRuntime) setActiveDownloadItemID(itemID string) {
+func (r *extensionRuntime) setActiveDownloadItemID(itemID string) {
 	r.activeDownloadMu.Lock()
 	defer r.activeDownloadMu.Unlock()
 	r.activeDownloadItemID = strings.TrimSpace(itemID)
 }
 
-func (r *ExtensionRuntime) clearActiveDownloadItemID() {
+func (r *extensionRuntime) clearActiveDownloadItemID() {
 	r.activeDownloadMu.Lock()
 	defer r.activeDownloadMu.Unlock()
 	r.activeDownloadItemID = ""
 }
 
-func (r *ExtensionRuntime) getActiveDownloadItemID() string {
+func (r *extensionRuntime) getActiveDownloadItemID() string {
 	r.activeDownloadMu.RLock()
 	defer r.activeDownloadMu.RUnlock()
 	return r.activeDownloadItemID
 }
 
-func newExtensionHTTPClient(ext *LoadedExtension, jar http.CookieJar, timeout time.Duration) *http.Client {
+func newExtensionHTTPClient(ext *loadedExtension, jar http.CookieJar, timeout time.Duration) *http.Client {
 	// Extension sandbox enforces HTTPS-only domains. Do not apply global
 	// allow_http scheme downgrade here, because some extension APIs (e.g.
 	// spotify-web) will redirect http -> https and can end up in 301 loops.
@@ -329,11 +329,11 @@ func (j *simpleCookieJar) Cookies(u *url.URL) []*http.Cookie {
 	return j.cookies[u.Host]
 }
 
-func (r *ExtensionRuntime) SetSettings(settings map[string]interface{}) {
+func (r *extensionRuntime) SetSettings(settings map[string]interface{}) {
 	r.settings = settings
 }
 
-func (r *ExtensionRuntime) RegisterAPIs(vm *goja.Runtime) {
+func (r *extensionRuntime) RegisterAPIs(vm *goja.Runtime) {
 	r.vm = vm
 
 	httpObj := vm.NewObject()
@@ -377,7 +377,9 @@ func (r *ExtensionRuntime) RegisterAPIs(vm *goja.Runtime) {
 	fileObj.Set("exists", r.fileExists)
 	fileObj.Set("delete", r.fileDelete)
 	fileObj.Set("read", r.fileRead)
+	fileObj.Set("readBytes", r.fileReadBytes)
 	fileObj.Set("write", r.fileWrite)
+	fileObj.Set("writeBytes", r.fileWriteBytes)
 	fileObj.Set("copy", r.fileCopy)
 	fileObj.Set("move", r.fileMove)
 	fileObj.Set("getSize", r.fileGetSize)
@@ -407,6 +409,8 @@ func (r *ExtensionRuntime) RegisterAPIs(vm *goja.Runtime) {
 	utilsObj.Set("stringifyJSON", r.stringifyJSON)
 	utilsObj.Set("encrypt", r.cryptoEncrypt)
 	utilsObj.Set("decrypt", r.cryptoDecrypt)
+	utilsObj.Set("encryptBlockCipher", r.encryptBlockCipher)
+	utilsObj.Set("decryptBlockCipher", r.decryptBlockCipher)
 	utilsObj.Set("generateKey", r.cryptoGenerateKey)
 	utilsObj.Set("randomUserAgent", r.randomUserAgent)
 	vm.Set("utils", utilsObj)

go_backend/extension_runtime_auth.go

@@ -52,7 +52,7 @@ func summarizeURLForLog(urlStr string) string {
 	return fmt.Sprintf("%s://%s%s", parsed.Scheme, parsed.Host, parsed.Path)
 }
 
-func (r *ExtensionRuntime) authOpenUrl(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authOpenUrl(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -99,7 +99,7 @@ func (r *ExtensionRuntime) authOpenUrl(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) authGetCode(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authGetCode(call goja.FunctionCall) goja.Value {
 	extensionAuthStateMu.RLock()
 	defer extensionAuthStateMu.RUnlock()
 
@@ -111,7 +111,7 @@ func (r *ExtensionRuntime) authGetCode(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(state.AuthCode)
 }
 
-func (r *ExtensionRuntime) authSetCode(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authSetCode(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(false)
 	}
@@ -149,7 +149,7 @@ func (r *ExtensionRuntime) authSetCode(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(true)
 }
 
-func (r *ExtensionRuntime) authClear(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authClear(call goja.FunctionCall) goja.Value {
 	extensionAuthStateMu.Lock()
 	delete(extensionAuthState, r.extensionID)
 	extensionAuthStateMu.Unlock()
@@ -162,7 +162,7 @@ func (r *ExtensionRuntime) authClear(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(true)
 }
 
-func (r *ExtensionRuntime) authIsAuthenticated(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authIsAuthenticated(call goja.FunctionCall) goja.Value {
 	extensionAuthStateMu.RLock()
 	defer extensionAuthStateMu.RUnlock()
 
@@ -178,7 +178,7 @@ func (r *ExtensionRuntime) authIsAuthenticated(call goja.FunctionCall) goja.Valu
 	return r.vm.ToValue(state.IsAuthenticated)
 }
 
-func (r *ExtensionRuntime) authGetTokens(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authGetTokens(call goja.FunctionCall) goja.Value {
 	extensionAuthStateMu.RLock()
 	defer extensionAuthStateMu.RUnlock()
 
@@ -228,7 +228,7 @@ func generatePKCEChallenge(verifier string) string {
 	return base64.RawURLEncoding.EncodeToString(hash[:])
 }
 
-func (r *ExtensionRuntime) authGeneratePKCE(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authGeneratePKCE(call goja.FunctionCall) goja.Value {
 	length := 64
 	if len(call.Arguments) > 0 && !goja.IsUndefined(call.Arguments[0]) {
 		if l, ok := call.Arguments[0].Export().(float64); ok && l >= 43 && l <= 128 {
@@ -265,7 +265,7 @@ func (r *ExtensionRuntime) authGeneratePKCE(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) authGetPKCE(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authGetPKCE(call goja.FunctionCall) goja.Value {
 	extensionAuthStateMu.RLock()
 	defer extensionAuthStateMu.RUnlock()
 
@@ -281,7 +281,7 @@ func (r *ExtensionRuntime) authGetPKCE(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) authStartOAuthWithPKCE(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authStartOAuthWithPKCE(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -385,7 +385,7 @@ func (r *ExtensionRuntime) authStartOAuthWithPKCE(call goja.FunctionCall) goja.V
 	})
 }
 
-func (r *ExtensionRuntime) authExchangeCodeWithPKCE(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) authExchangeCodeWithPKCE(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,

go_backend/extension_runtime_binary.go

@@ -0,0 +1,359 @@
+package gobackend
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/base64"
+	"encoding/hex"
+	"fmt"
+	"strings"
+
+	"github.com/dop251/goja"
+	"golang.org/x/crypto/blowfish"
+)
+
+type runtimeBlockCipherOptions struct {
+	Algorithm      string
+	Mode           string
+	Key            []byte
+	IV             []byte
+	InputEncoding  string
+	OutputEncoding string
+	Padding        string
+}
+
+func parseRuntimeOptionsArgument(call goja.FunctionCall, index int) map[string]interface{} {
+	if len(call.Arguments) <= index {
+		return nil
+	}
+
+	value := call.Arguments[index]
+	if goja.IsUndefined(value) || goja.IsNull(value) {
+		return nil
+	}
+
+	exported := value.Export()
+	if options, ok := exported.(map[string]interface{}); ok {
+		return options
+	}
+	return nil
+}
+
+func runtimeOptionString(options map[string]interface{}, key, defaultValue string) string {
+	if options == nil {
+		return defaultValue
+	}
+	raw, ok := options[key]
+	if !ok || raw == nil {
+		return defaultValue
+	}
+	switch value := raw.(type) {
+	case string:
+		if trimmed := strings.TrimSpace(value); trimmed != "" {
+			return trimmed
+		}
+	case []byte:
+		if len(value) > 0 {
+			return string(value)
+		}
+	}
+	return defaultValue
+}
+
+func runtimeOptionBool(options map[string]interface{}, key string, defaultValue bool) bool {
+	if options == nil {
+		return defaultValue
+	}
+	raw, ok := options[key]
+	if !ok || raw == nil {
+		return defaultValue
+	}
+	switch value := raw.(type) {
+	case bool:
+		return value
+	case int:
+		return value != 0
+	case int64:
+		return value != 0
+	case float64:
+		return value != 0
+	case string:
+		switch strings.ToLower(strings.TrimSpace(value)) {
+		case "1", "true", "yes", "on":
+			return true
+		case "0", "false", "no", "off":
+			return false
+		}
+	}
+	return defaultValue
+}
+
+func runtimeOptionInt64(options map[string]interface{}, key string, defaultValue int64) int64 {
+	if options == nil {
+		return defaultValue
+	}
+	raw, ok := options[key]
+	if !ok || raw == nil {
+		return defaultValue
+	}
+	switch value := raw.(type) {
+	case int:
+		return int64(value)
+	case int32:
+		return int64(value)
+	case int64:
+		return value
+	case float32:
+		return int64(value)
+	case float64:
+		return int64(value)
+	case string:
+		value = strings.TrimSpace(value)
+		if value == "" {
+			return defaultValue
+		}
+		var parsed int64
+		if _, err := fmt.Sscanf(value, "%d", &parsed); err == nil {
+			return parsed
+		}
+	}
+	return defaultValue
+}
+
+func runtimeOptionHasKey(options map[string]interface{}, key string) bool {
+	if options == nil {
+		return false
+	}
+	_, exists := options[key]
+	return exists
+}
+
+func decodeRuntimeBytesString(input, encoding string) ([]byte, error) {
+	switch strings.ToLower(strings.TrimSpace(encoding)) {
+	case "", "utf8", "utf-8", "text":
+		return []byte(input), nil
+	case "base64":
+		decoded, err := base64.StdEncoding.DecodeString(strings.TrimSpace(input))
+		if err != nil {
+			return nil, fmt.Errorf("invalid base64 data: %w", err)
+		}
+		return decoded, nil
+	case "hex":
+		decoded, err := hex.DecodeString(strings.TrimSpace(input))
+		if err != nil {
+			return nil, fmt.Errorf("invalid hex data: %w", err)
+		}
+		return decoded, nil
+	default:
+		return nil, fmt.Errorf("unsupported byte encoding: %s", encoding)
+	}
+}
+
+func decodeRuntimeBytesValue(raw interface{}, encoding string) ([]byte, error) {
+	switch value := raw.(type) {
+	case string:
+		return decodeRuntimeBytesString(value, encoding)
+	case []byte:
+		cloned := make([]byte, len(value))
+		copy(cloned, value)
+		return cloned, nil
+	case []interface{}:
+		decoded := make([]byte, len(value))
+		for i, item := range value {
+			switch num := item.(type) {
+			case int:
+				decoded[i] = byte(num)
+			case int64:
+				decoded[i] = byte(num)
+			case float64:
+				decoded[i] = byte(int(num))
+			default:
+				return nil, fmt.Errorf("unsupported byte array item at index %d", i)
+			}
+		}
+		return decoded, nil
+	default:
+		return nil, fmt.Errorf("unsupported byte payload type")
+	}
+}
+
+func encodeRuntimeBytes(data []byte, encoding string) (string, error) {
+	switch strings.ToLower(strings.TrimSpace(encoding)) {
+	case "", "base64":
+		return base64.StdEncoding.EncodeToString(data), nil
+	case "hex":
+		return hex.EncodeToString(data), nil
+	case "utf8", "utf-8", "text":
+		return string(data), nil
+	default:
+		return "", fmt.Errorf("unsupported byte encoding: %s", encoding)
+	}
+}
+
+func parseRuntimeBlockCipherOptions(options map[string]interface{}) (*runtimeBlockCipherOptions, error) {
+	parsed := &runtimeBlockCipherOptions{
+		Algorithm:      strings.ToLower(runtimeOptionString(options, "algorithm", "")),
+		Mode:           strings.ToLower(runtimeOptionString(options, "mode", "cbc")),
+		InputEncoding:  strings.ToLower(runtimeOptionString(options, "inputEncoding", "base64")),
+		OutputEncoding: strings.ToLower(runtimeOptionString(options, "outputEncoding", "base64")),
+		Padding:        strings.ToLower(runtimeOptionString(options, "padding", "none")),
+	}
+	if parsed.Algorithm == "" {
+		return nil, fmt.Errorf("algorithm is required")
+	}
+	if parsed.Mode == "" {
+		return nil, fmt.Errorf("mode is required")
+	}
+
+	key, err := decodeRuntimeBytesString(runtimeOptionString(options, "key", ""), runtimeOptionString(options, "keyEncoding", "utf8"))
+	if err != nil {
+		return nil, fmt.Errorf("invalid key: %w", err)
+	}
+	if len(key) == 0 {
+		return nil, fmt.Errorf("key is required")
+	}
+	parsed.Key = key
+
+	iv, err := decodeRuntimeBytesString(runtimeOptionString(options, "iv", ""), runtimeOptionString(options, "ivEncoding", "utf8"))
+	if err != nil {
+		return nil, fmt.Errorf("invalid iv: %w", err)
+	}
+	parsed.IV = iv
+	return parsed, nil
+}
+
+func newRuntimeBlockCipher(options *runtimeBlockCipherOptions) (cipher.Block, error) {
+	switch options.Algorithm {
+	case "blowfish":
+		return blowfish.NewCipher(options.Key)
+	case "aes":
+		return aes.NewCipher(options.Key)
+	default:
+		return nil, fmt.Errorf("unsupported block cipher algorithm: %s", options.Algorithm)
+	}
+}
+
+func applyPKCS7Padding(data []byte, blockSize int) []byte {
+	padding := blockSize - (len(data) % blockSize)
+	if padding == 0 {
+		padding = blockSize
+	}
+	out := make([]byte, len(data)+padding)
+	copy(out, data)
+	for i := len(data); i < len(out); i++ {
+		out[i] = byte(padding)
+	}
+	return out
+}
+
+func removePKCS7Padding(data []byte, blockSize int) ([]byte, error) {
+	if len(data) == 0 || len(data)%blockSize != 0 {
+		return nil, fmt.Errorf("invalid padded payload length")
+	}
+	padding := int(data[len(data)-1])
+	if padding <= 0 || padding > blockSize || padding > len(data) {
+		return nil, fmt.Errorf("invalid PKCS7 padding")
+	}
+	for i := len(data) - padding; i < len(data); i++ {
+		if int(data[i]) != padding {
+			return nil, fmt.Errorf("invalid PKCS7 padding")
+		}
+	}
+	return data[:len(data)-padding], nil
+}
+
+func (r *extensionRuntime) transformBlockCipher(call goja.FunctionCall, decrypt bool) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "data and options are required",
+		})
+	}
+
+	options := parseRuntimeOptionsArgument(call, 1)
+	parsedOptions, err := parseRuntimeBlockCipherOptions(options)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+	if parsedOptions.Mode != "cbc" {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("unsupported block cipher mode: %s", parsedOptions.Mode),
+		})
+	}
+
+	inputData, err := decodeRuntimeBytesValue(call.Arguments[0].Export(), parsedOptions.InputEncoding)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	block, err := newRuntimeBlockCipher(parsedOptions)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	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(),
+				})
+			}
+		}
+	} else {
+		cipher.NewCBCEncrypter(block, parsedOptions.IV).CryptBlocks(output, data)
+	}
+
+	encoded, err := encodeRuntimeBytes(output, parsedOptions.OutputEncoding)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success":    true,
+		"data":       encoded,
+		"block_size": block.BlockSize(),
+	})
+}
+
+func (r *extensionRuntime) encryptBlockCipher(call goja.FunctionCall) goja.Value {
+	return r.transformBlockCipher(call, false)
+}
+
+func (r *extensionRuntime) decryptBlockCipher(call goja.FunctionCall) goja.Value {
+	return r.transformBlockCipher(call, true)
+}

go_backend/extension_runtime_binary_test.go

@@ -0,0 +1,185 @@
+package gobackend
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/dop251/goja"
+)
+
+func newBinaryTestRuntime(t *testing.T, withFilePermission bool) *goja.Runtime {
+	t.Helper()
+
+	ext := &loadedExtension{
+		ID: "binary-test-ext",
+		Manifest: &ExtensionManifest{
+			Name: "binary-test-ext",
+			Permissions: ExtensionPermissions{
+				File: withFilePermission,
+			},
+		},
+		DataDir: t.TempDir(),
+	}
+
+	runtime := newExtensionRuntime(ext)
+	vm := goja.New()
+	runtime.RegisterAPIs(vm)
+	return vm
+}
+
+func decodeJSONResult[T any](t *testing.T, value goja.Value) T {
+	t.Helper()
+
+	var decoded T
+	if err := json.Unmarshal([]byte(value.String()), &decoded); err != nil {
+		t.Fatalf("failed to decode JSON result: %v", err)
+	}
+	return decoded
+}
+
+func TestExtensionRuntime_FileByteAPIs(t *testing.T) {
+	vm := newBinaryTestRuntime(t, true)
+
+	result, err := vm.RunString(`
+		(function() {
+			var first = file.writeBytes("bytes.bin", "AAEC", {encoding: "base64", truncate: true});
+			if (!first.success) throw new Error(first.error);
+
+			var second = file.writeBytes("bytes.bin", "0304ff", {encoding: "hex", append: true});
+			if (!second.success) throw new Error(second.error);
+
+			var all = file.readBytes("bytes.bin", {encoding: "hex"});
+			if (!all.success) throw new Error(all.error);
+
+			var slice = file.readBytes("bytes.bin", {offset: 2, length: 2, encoding: "hex"});
+			if (!slice.success) throw new Error(slice.error);
+
+			var tail = file.readBytes("bytes.bin", {offset: 6, length: 4, encoding: "hex"});
+			if (!tail.success) throw new Error(tail.error);
+
+			return JSON.stringify({
+				all: all.data,
+				slice: slice.data,
+				size: all.size,
+				sliceBytes: slice.bytes_read,
+				sliceEof: slice.eof,
+				tailBytes: tail.bytes_read,
+				tailEof: tail.eof
+			});
+		})()
+	`)
+	if err != nil {
+		t.Fatalf("file byte APIs failed: %v", err)
+	}
+
+	decoded := decodeJSONResult[struct {
+		All        string `json:"all"`
+		Slice      string `json:"slice"`
+		Size       int64  `json:"size"`
+		SliceBytes int    `json:"sliceBytes"`
+		SliceEof   bool   `json:"sliceEof"`
+		TailBytes  int    `json:"tailBytes"`
+		TailEof    bool   `json:"tailEof"`
+	}](t, result)
+
+	if decoded.All != "0001020304ff" {
+		t.Fatalf("all = %q", decoded.All)
+	}
+	if decoded.Slice != "0203" {
+		t.Fatalf("slice = %q", decoded.Slice)
+	}
+	if decoded.Size != 6 {
+		t.Fatalf("size = %d", decoded.Size)
+	}
+	if decoded.SliceBytes != 2 {
+		t.Fatalf("slice bytes = %d", decoded.SliceBytes)
+	}
+	if decoded.SliceEof {
+		t.Fatal("slice should not be EOF")
+	}
+	if decoded.TailBytes != 0 || !decoded.TailEof {
+		t.Fatalf("tail read mismatch: bytes=%d eof=%v", decoded.TailBytes, decoded.TailEof)
+	}
+}
+
+func TestExtensionRuntime_BlockCipherCBCSupportsBlowfish(t *testing.T) {
+	vm := newBinaryTestRuntime(t, false)
+
+	result, err := vm.RunString(`
+		(function() {
+			var options = {
+				algorithm: "blowfish",
+				mode: "cbc",
+				key: "0123456789ABCDEFF0E1D2C3B4A59687",
+				keyEncoding: "hex",
+				iv: "0001020304050607",
+				ivEncoding: "hex",
+				inputEncoding: "hex",
+				outputEncoding: "hex",
+				padding: "none"
+			};
+			var enc = utils.encryptBlockCipher("00112233445566778899aabbccddeeff", options);
+			if (!enc.success) throw new Error(enc.error);
+			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("blowfish block cipher failed: %v", err)
+	}
+
+	decoded := decodeJSONResult[struct {
+		Enc string `json:"enc"`
+		Dec string `json:"dec"`
+	}](t, result)
+
+	if decoded.Dec != "00112233445566778899aabbccddeeff" {
+		t.Fatalf("dec = %q", decoded.Dec)
+	}
+	if decoded.Enc == decoded.Dec {
+		t.Fatal("expected ciphertext to differ from plaintext")
+	}
+}
+
+func TestExtensionRuntime_BlockCipherCBCSupportsAES(t *testing.T) {
+	vm := newBinaryTestRuntime(t, false)
+
+	result, err := vm.RunString(`
+		(function() {
+			var options = {
+				algorithm: "aes",
+				mode: "cbc",
+				key: "000102030405060708090a0b0c0d0e0f",
+				keyEncoding: "hex",
+				iv: "0f0e0d0c0b0a09080706050403020100",
+				ivEncoding: "hex",
+				inputEncoding: "utf8",
+				outputEncoding: "base64",
+				padding: "pkcs7"
+			};
+			var enc = utils.encryptBlockCipher("hello generic cbc", options);
+			if (!enc.success) throw new Error(enc.error);
+			var dec = utils.decryptBlockCipher(enc.data, {
+				algorithm: "aes",
+				mode: "cbc",
+				key: options.key,
+				keyEncoding: options.keyEncoding,
+				iv: options.iv,
+				ivEncoding: options.ivEncoding,
+				inputEncoding: "base64",
+				outputEncoding: "utf8",
+				padding: "pkcs7"
+			});
+			if (!dec.success) throw new Error(dec.error);
+			return dec.data;
+		})()
+	`)
+	if err != nil {
+		t.Fatalf("aes block cipher failed: %v", err)
+	}
+
+	if result.String() != "hello generic cbc" {
+		t.Fatalf("unexpected decrypted value: %q", result.String())
+	}
+}

go_backend/extension_runtime_ffmpeg.go

@@ -50,7 +50,7 @@ func ClearFFmpegCommand(commandID string) {
 	delete(ffmpegCommands, commandID)
 }
 
-func (r *ExtensionRuntime) ffmpegExecute(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) ffmpegExecute(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -107,7 +107,7 @@ func (r *ExtensionRuntime) ffmpegExecute(call goja.FunctionCall) goja.Value {
 	}
 }
 
-func (r *ExtensionRuntime) ffmpegGetInfo(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) ffmpegGetInfo(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -134,7 +134,7 @@ func (r *ExtensionRuntime) ffmpegGetInfo(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) ffmpegConvert(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) ffmpegConvert(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,

go_backend/extension_runtime_file.go

@@ -71,7 +71,7 @@ func isPathWithinBase(baseDir, targetPath string) bool {
 	return true
 }
 
-func (r *ExtensionRuntime) validatePath(path string) (string, error) {
+func (r *extensionRuntime) validatePath(path string) (string, error) {
 	if !r.manifest.Permissions.File {
 		return "", fmt.Errorf("file access denied: extension does not have 'file' permission")
 	}
@@ -106,7 +106,7 @@ func (r *ExtensionRuntime) validatePath(path string) (string, error) {
 	return absPath, nil
 }
 
-func (r *ExtensionRuntime) fileDownload(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileDownload(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -271,7 +271,7 @@ func (r *ExtensionRuntime) fileDownload(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) fileExists(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileExists(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(false)
 	}
@@ -286,7 +286,7 @@ func (r *ExtensionRuntime) fileExists(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(err == nil)
 }
 
-func (r *ExtensionRuntime) fileDelete(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileDelete(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -315,7 +315,7 @@ func (r *ExtensionRuntime) fileDelete(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) fileRead(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileRead(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -346,7 +346,105 @@ func (r *ExtensionRuntime) fileRead(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) fileWrite(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileReadBytes(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "path is required",
+		})
+	}
+
+	path := call.Arguments[0].String()
+	fullPath, err := r.validatePath(path)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	options := parseRuntimeOptionsArgument(call, 1)
+	offset := runtimeOptionInt64(options, "offset", 0)
+	length := runtimeOptionInt64(options, "length", -1)
+	encoding := runtimeOptionString(options, "encoding", "base64")
+	if offset < 0 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "offset must be >= 0",
+		})
+	}
+
+	file, err := os.Open(fullPath)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+	defer file.Close()
+
+	info, err := file.Stat()
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	size := info.Size()
+	if offset > size {
+		offset = size
+	}
+	if _, err := file.Seek(offset, io.SeekStart); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("failed to seek file: %v", err),
+		})
+	}
+
+	var data []byte
+	switch {
+	case length == 0:
+		data = []byte{}
+	case length > 0:
+		buf := make([]byte, int(length))
+		n, readErr := file.Read(buf)
+		if readErr != nil && readErr != io.EOF {
+			return r.vm.ToValue(map[string]interface{}{
+				"success": false,
+				"error":   fmt.Sprintf("failed to read file: %v", readErr),
+			})
+		}
+		data = buf[:n]
+	default:
+		data, err = io.ReadAll(file)
+		if err != nil {
+			return r.vm.ToValue(map[string]interface{}{
+				"success": false,
+				"error":   fmt.Sprintf("failed to read file: %v", err),
+			})
+		}
+	}
+
+	encoded, err := encodeRuntimeBytes(data, encoding)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success":    true,
+		"data":       encoded,
+		"bytes_read": len(data),
+		"offset":     offset,
+		"size":       size,
+		"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{}{
 			"success": false,
@@ -386,7 +484,108 @@ func (r *ExtensionRuntime) fileWrite(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) fileCopy(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileWriteBytes(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "path and data are required",
+		})
+	}
+
+	path := call.Arguments[0].String()
+	fullPath, err := r.validatePath(path)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	options := parseRuntimeOptionsArgument(call, 2)
+	appendMode := runtimeOptionBool(options, "append", false)
+	truncate := runtimeOptionBool(options, "truncate", false)
+	hasOffset := runtimeOptionHasKey(options, "offset")
+	offset := runtimeOptionInt64(options, "offset", 0)
+	encoding := runtimeOptionString(options, "encoding", "base64")
+
+	if appendMode && hasOffset {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "append and offset cannot be used together",
+		})
+	}
+	if offset < 0 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "offset must be >= 0",
+		})
+	}
+
+	data, err := decodeRuntimeBytesValue(call.Arguments[1].Export(), encoding)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	dir := filepath.Dir(fullPath)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("failed to create directory: %v", err),
+		})
+	}
+
+	flags := os.O_CREATE | os.O_WRONLY
+	if appendMode {
+		flags |= os.O_APPEND
+	}
+	if truncate {
+		flags |= os.O_TRUNC
+	}
+
+	file, err := os.OpenFile(fullPath, flags, 0644)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+	defer file.Close()
+
+	if hasOffset && !appendMode {
+		if _, err := file.Seek(offset, io.SeekStart); err != nil {
+			return r.vm.ToValue(map[string]interface{}{
+				"success": false,
+				"error":   fmt.Sprintf("failed to seek file: %v", err),
+			})
+		}
+	}
+
+	written, err := file.Write(data)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	info, statErr := file.Stat()
+	size := int64(0)
+	if statErr == nil {
+		size = info.Size()
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success":       true,
+		"path":          fullPath,
+		"bytes_written": written,
+		"size":          size,
+	})
+}
+
+func (r *extensionRuntime) fileCopy(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -459,7 +658,7 @@ func (r *ExtensionRuntime) fileCopy(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) fileMove(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileMove(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -507,7 +706,7 @@ func (r *ExtensionRuntime) fileMove(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) fileGetSize(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fileGetSize(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,

go_backend/extension_runtime_http.go

@@ -17,7 +17,7 @@ type HTTPResponse struct {
 	Headers    map[string]string `json:"headers"`
 }
 
-func (r *ExtensionRuntime) validateDomain(urlStr string) error {
+func (r *extensionRuntime) validateDomain(urlStr string) error {
 	parsed, err := url.Parse(urlStr)
 	if err != nil {
 		return fmt.Errorf("invalid URL: %w", err)
@@ -49,7 +49,7 @@ func (r *ExtensionRuntime) validateDomain(urlStr string) error {
 	return nil
 }
 
-func (r *ExtensionRuntime) httpGet(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpGet(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"error": "URL is required",
@@ -124,7 +124,7 @@ func (r *ExtensionRuntime) httpGet(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) httpPost(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpPost(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"error": "URL is required",
@@ -221,7 +221,7 @@ func (r *ExtensionRuntime) httpPost(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) httpRequest(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpRequest(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"error": "URL is required",
@@ -330,19 +330,19 @@ func (r *ExtensionRuntime) httpRequest(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) httpPut(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpPut(call goja.FunctionCall) goja.Value {
 	return r.httpMethodShortcut("PUT", call)
 }
 
-func (r *ExtensionRuntime) httpDelete(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpDelete(call goja.FunctionCall) goja.Value {
 	return r.httpMethodShortcut("DELETE", call)
 }
 
-func (r *ExtensionRuntime) httpPatch(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpPatch(call goja.FunctionCall) goja.Value {
 	return r.httpMethodShortcut("PATCH", call)
 }
 
-func (r *ExtensionRuntime) httpMethodShortcut(method string, call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpMethodShortcut(method string, call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(map[string]interface{}{
 			"error": "URL is required",
@@ -455,7 +455,7 @@ func (r *ExtensionRuntime) httpMethodShortcut(method string, call goja.FunctionC
 	})
 }
 
-func (r *ExtensionRuntime) httpClearCookies(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) httpClearCookies(call goja.FunctionCall) goja.Value {
 	if jar, ok := r.cookieJar.(*simpleCookieJar); ok {
 		jar.mu.Lock()
 		jar.cookies = make(map[string][]*http.Cookie)

go_backend/extension_runtime_matching.go

@@ -6,7 +6,7 @@ import (
 	"github.com/dop251/goja"
 )
 
-func (r *ExtensionRuntime) matchingCompareStrings(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) matchingCompareStrings(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(0.0)
 	}
@@ -22,7 +22,7 @@ func (r *ExtensionRuntime) matchingCompareStrings(call goja.FunctionCall) goja.V
 	return r.vm.ToValue(similarity)
 }
 
-func (r *ExtensionRuntime) matchingCompareDuration(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) matchingCompareDuration(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(false)
 	}
@@ -43,7 +43,7 @@ func (r *ExtensionRuntime) matchingCompareDuration(call goja.FunctionCall) goja.
 	return r.vm.ToValue(diff <= tolerance)
 }
 
-func (r *ExtensionRuntime) matchingNormalizeString(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) matchingNormalizeString(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}

go_backend/extension_runtime_polyfills.go

@@ -12,7 +12,7 @@ import (
 	"github.com/dop251/goja"
 )
 
-func (r *ExtensionRuntime) fetchPolyfill(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) fetchPolyfill(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.createFetchError("URL is required")
 	}
@@ -133,7 +133,7 @@ func (r *ExtensionRuntime) fetchPolyfill(call goja.FunctionCall) goja.Value {
 	return responseObj
 }
 
-func (r *ExtensionRuntime) createFetchError(message string) goja.Value {
+func (r *extensionRuntime) createFetchError(message string) goja.Value {
 	errorObj := r.vm.NewObject()
 	errorObj.Set("ok", false)
 	errorObj.Set("status", 0)
@@ -148,7 +148,7 @@ func (r *ExtensionRuntime) createFetchError(message string) goja.Value {
 	return errorObj
 }
 
-func (r *ExtensionRuntime) atobPolyfill(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) atobPolyfill(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -164,7 +164,7 @@ func (r *ExtensionRuntime) atobPolyfill(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(string(decoded))
 }
 
-func (r *ExtensionRuntime) btoaPolyfill(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) btoaPolyfill(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -172,7 +172,7 @@ func (r *ExtensionRuntime) btoaPolyfill(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(base64.StdEncoding.EncodeToString([]byte(input)))
 }
 
-func (r *ExtensionRuntime) registerTextEncoderDecoder(vm *goja.Runtime) {
+func (r *extensionRuntime) registerTextEncoderDecoder(vm *goja.Runtime) {
 	vm.Set("TextEncoder", func(call goja.ConstructorCall) *goja.Object {
 		encoder := call.This
 		encoder.Set("encoding", "utf-8")
@@ -252,7 +252,7 @@ func (r *ExtensionRuntime) registerTextEncoderDecoder(vm *goja.Runtime) {
 	})
 }
 
-func (r *ExtensionRuntime) registerURLClass(vm *goja.Runtime) {
+func (r *extensionRuntime) registerURLClass(vm *goja.Runtime) {
 	vm.Set("URL", func(call goja.ConstructorCall) *goja.Object {
 		urlObj := call.This
 
@@ -416,7 +416,7 @@ func (r *ExtensionRuntime) registerURLClass(vm *goja.Runtime) {
 	})
 }
 
-func (r *ExtensionRuntime) registerJSONGlobal(vm *goja.Runtime) {
+func (r *extensionRuntime) registerJSONGlobal(vm *goja.Runtime) {
 	jsonScript := `
 		if (typeof JSON === 'undefined') {
 			var JSON = {

go_backend/extension_runtime_storage.go

@@ -21,7 +21,7 @@ const (
 	storageFlushRetryDelay   = 2 * time.Second
 )
 
-func (r *ExtensionRuntime) getStoragePath() string {
+func (r *extensionRuntime) getStoragePath() string {
 	return filepath.Join(r.dataDir, "storage.json")
 }
 
@@ -36,7 +36,7 @@ func cloneInterfaceMap(src map[string]interface{}) map[string]interface{} {
 	return dst
 }
 
-func (r *ExtensionRuntime) ensureStorageLoaded() error {
+func (r *extensionRuntime) ensureStorageLoaded() error {
 	r.storageMu.RLock()
 	if r.storageLoaded {
 		r.storageMu.RUnlock()
@@ -74,7 +74,7 @@ func (r *ExtensionRuntime) ensureStorageLoaded() error {
 	return nil
 }
 
-func (r *ExtensionRuntime) loadStorage() (map[string]interface{}, error) {
+func (r *extensionRuntime) loadStorage() (map[string]interface{}, error) {
 	if err := r.ensureStorageLoaded(); err != nil {
 		return nil, err
 	}
@@ -84,7 +84,7 @@ func (r *ExtensionRuntime) loadStorage() (map[string]interface{}, error) {
 	return cloneInterfaceMap(r.storageCache), nil
 }
 
-func (r *ExtensionRuntime) queueStorageFlushLocked(delay time.Duration) {
+func (r *extensionRuntime) queueStorageFlushLocked(delay time.Duration) {
 	if r.storageClosed {
 		return
 	}
@@ -94,7 +94,7 @@ func (r *ExtensionRuntime) queueStorageFlushLocked(delay time.Duration) {
 	r.storageTimer = time.AfterFunc(delay, r.flushStorageDirtyAsync)
 }
 
-func (r *ExtensionRuntime) persistStorageSnapshot(storage map[string]interface{}) error {
+func (r *extensionRuntime) persistStorageSnapshot(storage map[string]interface{}) error {
 	data, err := json.Marshal(storage)
 	if err != nil {
 		return err
@@ -106,13 +106,13 @@ func (r *ExtensionRuntime) persistStorageSnapshot(storage map[string]interface{}
 	return os.WriteFile(r.getStoragePath(), data, 0600)
 }
 
-func (r *ExtensionRuntime) flushStorageDirtyAsync() {
+func (r *extensionRuntime) flushStorageDirtyAsync() {
 	if err := r.flushStorageDirty(); err != nil {
 		GoLog("[Extension:%s] Storage flush error: %v\n", r.extensionID, err)
 	}
 }
 
-func (r *ExtensionRuntime) flushStorageDirty() error {
+func (r *extensionRuntime) flushStorageDirty() error {
 	r.storageMu.Lock()
 	if r.storageClosed {
 		r.storageTimer = nil
@@ -140,7 +140,7 @@ func (r *ExtensionRuntime) flushStorageDirty() error {
 	return nil
 }
 
-func (r *ExtensionRuntime) flushStorageNow() error {
+func (r *extensionRuntime) flushStorageNow() error {
 	r.storageMu.Lock()
 	if r.storageTimer != nil {
 		r.storageTimer.Stop()
@@ -157,7 +157,7 @@ func (r *ExtensionRuntime) flushStorageNow() error {
 	return r.persistStorageSnapshot(snapshot)
 }
 
-func (r *ExtensionRuntime) closeStorageFlusher() {
+func (r *extensionRuntime) closeStorageFlusher() {
 	r.storageMu.Lock()
 	r.storageClosed = true
 	r.storageDirty = false
@@ -168,7 +168,7 @@ func (r *ExtensionRuntime) closeStorageFlusher() {
 	r.storageMu.Unlock()
 }
 
-func (r *ExtensionRuntime) storageGet(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) storageGet(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return goja.Undefined()
 	}
@@ -193,7 +193,7 @@ func (r *ExtensionRuntime) storageGet(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(value)
 }
 
-func (r *ExtensionRuntime) storageSet(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) storageSet(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(false)
 	}
@@ -225,7 +225,7 @@ func (r *ExtensionRuntime) storageSet(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(true)
 }
 
-func (r *ExtensionRuntime) storageRemove(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) storageRemove(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(false)
 	}
@@ -254,15 +254,15 @@ func (r *ExtensionRuntime) storageRemove(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(true)
 }
 
-func (r *ExtensionRuntime) getCredentialsPath() string {
+func (r *extensionRuntime) getCredentialsPath() string {
 	return filepath.Join(r.dataDir, ".credentials.enc")
 }
 
-func (r *ExtensionRuntime) getSaltPath() string {
+func (r *extensionRuntime) getSaltPath() string {
 	return filepath.Join(r.dataDir, ".cred_salt")
 }
 
-func (r *ExtensionRuntime) getOrCreateSalt() ([]byte, error) {
+func (r *extensionRuntime) getOrCreateSalt() ([]byte, error) {
 	saltPath := r.getSaltPath()
 
 	salt, err := os.ReadFile(saltPath)
@@ -282,7 +282,7 @@ func (r *ExtensionRuntime) getOrCreateSalt() ([]byte, error) {
 	return salt, nil
 }
 
-func (r *ExtensionRuntime) getEncryptionKey() ([]byte, error) {
+func (r *extensionRuntime) getEncryptionKey() ([]byte, error) {
 	salt, err := r.getOrCreateSalt()
 	if err != nil {
 		return nil, err
@@ -293,7 +293,7 @@ func (r *ExtensionRuntime) getEncryptionKey() ([]byte, error) {
 	return hash[:], nil
 }
 
-func (r *ExtensionRuntime) ensureCredentialsLoaded() error {
+func (r *extensionRuntime) ensureCredentialsLoaded() error {
 	r.credentialsMu.RLock()
 	if r.credentialsLoaded {
 		r.credentialsMu.RUnlock()
@@ -340,7 +340,7 @@ func (r *ExtensionRuntime) ensureCredentialsLoaded() error {
 	return nil
 }
 
-func (r *ExtensionRuntime) loadCredentials() (map[string]interface{}, error) {
+func (r *extensionRuntime) loadCredentials() (map[string]interface{}, error) {
 	if err := r.ensureCredentialsLoaded(); err != nil {
 		return nil, err
 	}
@@ -350,7 +350,7 @@ func (r *ExtensionRuntime) loadCredentials() (map[string]interface{}, error) {
 	return cloneInterfaceMap(r.credentialsCache), nil
 }
 
-func (r *ExtensionRuntime) saveCredentials(creds map[string]interface{}) error {
+func (r *extensionRuntime) saveCredentials(creds map[string]interface{}) error {
 	data, err := json.Marshal(creds)
 	if err != nil {
 		return err
@@ -377,7 +377,7 @@ func (r *ExtensionRuntime) saveCredentials(creds map[string]interface{}) error {
 	return nil
 }
 
-func (r *ExtensionRuntime) credentialsStore(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) credentialsStore(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -414,7 +414,7 @@ func (r *ExtensionRuntime) credentialsStore(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) credentialsGet(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) credentialsGet(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return goja.Undefined()
 	}
@@ -439,7 +439,7 @@ func (r *ExtensionRuntime) credentialsGet(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(value)
 }
 
-func (r *ExtensionRuntime) credentialsRemove(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) credentialsRemove(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(false)
 	}
@@ -464,7 +464,7 @@ func (r *ExtensionRuntime) credentialsRemove(call goja.FunctionCall) goja.Value
 	return r.vm.ToValue(true)
 }
 
-func (r *ExtensionRuntime) credentialsHas(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) credentialsHas(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue(false)
 	}

go_backend/extension_runtime_storage_test.go

@@ -11,7 +11,7 @@ import (
 	"github.com/dop251/goja"
 )
 
-func setStorageValue(t *testing.T, runtime *ExtensionRuntime, key string, value interface{}) {
+func setStorageValue(t *testing.T, runtime *extensionRuntime, key string, value interface{}) {
 	t.Helper()
 	result := runtime.storageSet(goja.FunctionCall{
 		Arguments: []goja.Value{
@@ -39,7 +39,7 @@ func readStorageMap(t *testing.T, storagePath string) map[string]interface{} {
 }
 
 func TestExtensionRuntimeStorage_DebouncedWriteCompactJSON(t *testing.T) {
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID: "storage-test",
 		Manifest: &ExtensionManifest{
 			Name: "storage-test",
@@ -47,7 +47,7 @@ func TestExtensionRuntimeStorage_DebouncedWriteCompactJSON(t *testing.T) {
 		DataDir: t.TempDir(),
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 	runtime.storageFlushDelay = 25 * time.Millisecond
 	runtime.RegisterAPIs(goja.New())
 
@@ -86,7 +86,7 @@ func TestExtensionRuntimeStorage_DebouncedWriteCompactJSON(t *testing.T) {
 }
 
 func TestUnloadExtension_FlushesPendingStorage(t *testing.T) {
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID: "unload-storage-test",
 		Manifest: &ExtensionManifest{
 			Name: "unload-storage-test",
@@ -95,13 +95,13 @@ func TestUnloadExtension_FlushesPendingStorage(t *testing.T) {
 		VM:      goja.New(),
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 	runtime.storageFlushDelay = time.Hour
 	runtime.RegisterAPIs(ext.VM)
 	ext.runtime = runtime
 
-	manager := &ExtensionManager{
-		extensions: map[string]*LoadedExtension{
+	manager := &extensionManager{
+		extensions: map[string]*loadedExtension{
 			ext.ID: ext,
 		},
 	}

go_backend/extension_runtime_utils.go

@@ -16,7 +16,7 @@ import (
 	"github.com/dop251/goja"
 )
 
-func (r *ExtensionRuntime) base64Encode(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) base64Encode(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -24,7 +24,7 @@ func (r *ExtensionRuntime) base64Encode(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(base64.StdEncoding.EncodeToString([]byte(input)))
 }
 
-func (r *ExtensionRuntime) base64Decode(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) base64Decode(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -36,7 +36,7 @@ func (r *ExtensionRuntime) base64Decode(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(string(decoded))
 }
 
-func (r *ExtensionRuntime) md5Hash(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) md5Hash(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -45,7 +45,7 @@ func (r *ExtensionRuntime) md5Hash(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(hex.EncodeToString(hash[:]))
 }
 
-func (r *ExtensionRuntime) sha256Hash(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) sha256Hash(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -54,7 +54,7 @@ func (r *ExtensionRuntime) sha256Hash(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(hex.EncodeToString(hash[:]))
 }
 
-func (r *ExtensionRuntime) hmacSHA256(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) hmacSHA256(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue("")
 	}
@@ -66,7 +66,7 @@ func (r *ExtensionRuntime) hmacSHA256(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(hex.EncodeToString(mac.Sum(nil)))
 }
 
-func (r *ExtensionRuntime) hmacSHA256Base64(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) hmacSHA256Base64(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue("")
 	}
@@ -78,7 +78,7 @@ func (r *ExtensionRuntime) hmacSHA256Base64(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(base64.StdEncoding.EncodeToString(mac.Sum(nil)))
 }
 
-func (r *ExtensionRuntime) hmacSHA1(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) hmacSHA1(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue([]byte{})
 	}
@@ -130,7 +130,7 @@ func (r *ExtensionRuntime) hmacSHA1(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(jsArray)
 }
 
-func (r *ExtensionRuntime) parseJSON(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) parseJSON(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return goja.Undefined()
 	}
@@ -145,7 +145,7 @@ func (r *ExtensionRuntime) parseJSON(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(result)
 }
 
-func (r *ExtensionRuntime) stringifyJSON(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) stringifyJSON(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -160,7 +160,7 @@ func (r *ExtensionRuntime) stringifyJSON(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(string(data))
 }
 
-func (r *ExtensionRuntime) cryptoEncrypt(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) cryptoEncrypt(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -187,7 +187,7 @@ func (r *ExtensionRuntime) cryptoEncrypt(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) cryptoDecrypt(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) cryptoDecrypt(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 2 {
 		return r.vm.ToValue(map[string]interface{}{
 			"success": false,
@@ -222,7 +222,7 @@ func (r *ExtensionRuntime) cryptoDecrypt(call goja.FunctionCall) goja.Value {
 	})
 }
 
-func (r *ExtensionRuntime) cryptoGenerateKey(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) cryptoGenerateKey(call goja.FunctionCall) goja.Value {
 	length := 32
 	if len(call.Arguments) > 0 && !goja.IsUndefined(call.Arguments[0]) {
 		if l, ok := call.Arguments[0].Export().(float64); ok {
@@ -245,35 +245,35 @@ func (r *ExtensionRuntime) cryptoGenerateKey(call goja.FunctionCall) goja.Value
 	})
 }
 
-func (r *ExtensionRuntime) randomUserAgent(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) randomUserAgent(call goja.FunctionCall) goja.Value {
 	return r.vm.ToValue(getRandomUserAgent())
 }
 
-func (r *ExtensionRuntime) logDebug(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) logDebug(call goja.FunctionCall) goja.Value {
 	msg := r.formatLogArgs(call.Arguments)
 	GoLog("[Extension:%s:DEBUG] %s\n", r.extensionID, msg)
 	return goja.Undefined()
 }
 
-func (r *ExtensionRuntime) logInfo(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) logInfo(call goja.FunctionCall) goja.Value {
 	msg := r.formatLogArgs(call.Arguments)
 	GoLog("[Extension:%s:INFO] %s\n", r.extensionID, msg)
 	return goja.Undefined()
 }
 
-func (r *ExtensionRuntime) logWarn(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) logWarn(call goja.FunctionCall) goja.Value {
 	msg := r.formatLogArgs(call.Arguments)
 	GoLog("[Extension:%s:WARN] %s\n", r.extensionID, msg)
 	return goja.Undefined()
 }
 
-func (r *ExtensionRuntime) logError(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) logError(call goja.FunctionCall) goja.Value {
 	msg := r.formatLogArgs(call.Arguments)
 	GoLog("[Extension:%s:ERROR] %s\n", r.extensionID, msg)
 	return goja.Undefined()
 }
 
-func (r *ExtensionRuntime) formatLogArgs(args []goja.Value) string {
+func (r *extensionRuntime) formatLogArgs(args []goja.Value) string {
 	parts := make([]string, len(args))
 	for i, arg := range args {
 		parts[i] = fmt.Sprintf("%v", arg.Export())
@@ -281,7 +281,7 @@ func (r *ExtensionRuntime) formatLogArgs(args []goja.Value) string {
 	return strings.Join(parts, " ")
 }
 
-func (r *ExtensionRuntime) sanitizeFilenameWrapper(call goja.FunctionCall) goja.Value {
+func (r *extensionRuntime) sanitizeFilenameWrapper(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) < 1 {
 		return r.vm.ToValue("")
 	}
@@ -289,7 +289,7 @@ func (r *ExtensionRuntime) sanitizeFilenameWrapper(call goja.FunctionCall) goja.
 	return r.vm.ToValue(sanitizeFilename(input))
 }
 
-func (r *ExtensionRuntime) RegisterGoBackendAPIs(vm *goja.Runtime) {
+func (r *extensionRuntime) RegisterGoBackendAPIs(vm *goja.Runtime) {
 	gobackendObj := vm.Get("gobackend")
 	if gobackendObj == nil || goja.IsUndefined(gobackendObj) {
 		gobackendObj = vm.NewObject()

go_backend/extension_store.go

@@ -295,7 +295,7 @@ func (s *extensionStore) getExtensionsWithStatus(forceRefresh bool) ([]storeExte
 		return nil, err
 	}
 
-	manager := GetExtensionManager()
+	manager := getExtensionManager()
 	installed := make(map[string]string) // id -> version
 
 	if manager != nil {

go_backend/extension_test.go

@@ -99,7 +99,7 @@ func TestIsDomainAllowed(t *testing.T) {
 
 func TestExtensionRuntime_NetworkSandbox(t *testing.T) {
 	// Create a mock extension with limited network permissions
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID: "test-ext",
 		Manifest: &ExtensionManifest{
 			Name: "test-ext",
@@ -110,7 +110,7 @@ func TestExtensionRuntime_NetworkSandbox(t *testing.T) {
 		DataDir: t.TempDir(),
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 
 	if err := runtime.validateDomain("https://api.allowed.com/path"); err != nil {
 		t.Errorf("Expected api.allowed.com to be allowed, got error: %v", err)
@@ -132,7 +132,7 @@ func TestExtensionRuntime_NetworkSandbox(t *testing.T) {
 func TestExtensionRuntime_FileSandbox(t *testing.T) {
 	tempDir := t.TempDir()
 
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID: "test-ext",
 		Manifest: &ExtensionManifest{
 			Name: "test-ext",
@@ -143,7 +143,7 @@ func TestExtensionRuntime_FileSandbox(t *testing.T) {
 		DataDir: tempDir,
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 
 	validPath, err := runtime.validatePath("test.txt")
 	if err != nil {
@@ -177,7 +177,7 @@ func TestExtensionRuntime_FileSandbox(t *testing.T) {
 		t.Error("Expected absolute path to be blocked")
 	}
 
-	extNoFile := &LoadedExtension{
+	extNoFile := &loadedExtension{
 		ID: "test-ext-no-file",
 		Manifest: &ExtensionManifest{
 			Name: "test-ext-no-file",
@@ -187,7 +187,7 @@ func TestExtensionRuntime_FileSandbox(t *testing.T) {
 		},
 		DataDir: tempDir,
 	}
-	runtimeNoFile := NewExtensionRuntime(extNoFile)
+	runtimeNoFile := newExtensionRuntime(extNoFile)
 	_, err = runtimeNoFile.validatePath("test.txt")
 	if err == nil {
 		t.Error("Expected file access to be denied without file permission")
@@ -195,7 +195,7 @@ func TestExtensionRuntime_FileSandbox(t *testing.T) {
 }
 
 func TestExtensionRuntime_UtilityFunctions(t *testing.T) {
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID: "test-ext",
 		Manifest: &ExtensionManifest{
 			Name: "test-ext",
@@ -203,7 +203,7 @@ func TestExtensionRuntime_UtilityFunctions(t *testing.T) {
 		DataDir: t.TempDir(),
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 	vm := goja.New()
 	runtime.RegisterAPIs(vm)
 
@@ -243,7 +243,7 @@ func TestExtensionRuntime_UtilityFunctions(t *testing.T) {
 
 func TestExtensionRuntime_SSRFProtection(t *testing.T) {
 	// Create extension with limited network permissions
-	ext := &LoadedExtension{
+	ext := &loadedExtension{
 		ID: "test-ext",
 		Manifest: &ExtensionManifest{
 			Name: "test-ext",
@@ -254,7 +254,7 @@ func TestExtensionRuntime_SSRFProtection(t *testing.T) {
 		DataDir: t.TempDir(),
 	}
 
-	runtime := NewExtensionRuntime(ext)
+	runtime := newExtensionRuntime(ext)
 
 	privateIPs := []string{
 		"http://localhost/admin",

go_backend/extension_timeout.go

@@ -53,7 +53,7 @@ func RunWithTimeout(vm *goja.Runtime, script string, timeout time.Duration) (goj
 						IsTimeout: true,
 					}}
 				} else {
-					GoLog("[ExtensionRuntime] panic during JS execution: %v\n%s\n", r, string(debug.Stack()))
+					GoLog("[extensionRuntime] panic during JS execution: %v\n%s\n", r, string(debug.Stack()))
 					resultCh <- result{nil, fmt.Errorf("panic during execution: %v", r)}
 				}
 			}
@@ -90,7 +90,7 @@ func RunWithTimeout(vm *goja.Runtime, script string, timeout time.Duration) (goj
 		case <-time.After(60 * time.Second):
 			// Goroutine is truly stuck (e.g. HTTP read with no timeout).
 			// Log a warning — the VM should NOT be reused after this.
-			GoLog("[ExtensionRuntime] WARNING: JS goroutine did not exit within 60s after interrupt, VM may be unsafe\n")
+			GoLog("[extensionRuntime] WARNING: JS goroutine did not exit within 60s after interrupt, VM may be unsafe\n")
 			return nil, &JSExecutionError{
 				Message:   "execution timeout exceeded (force)",
 				IsTimeout: true,

go_backend/library_scan.go

@@ -24,13 +24,18 @@ type LibraryScanResult struct {
 	FileModTime          int64  `json:"fileModTime,omitempty"` // Unix timestamp in milliseconds
 	ISRC                 string `json:"isrc,omitempty"`
 	TrackNumber          int    `json:"trackNumber,omitempty"`
+	TotalTracks          int    `json:"totalTracks,omitempty"`
 	DiscNumber           int    `json:"discNumber,omitempty"`
+	TotalDiscs           int    `json:"totalDiscs,omitempty"`
 	Duration             int    `json:"duration,omitempty"`
 	ReleaseDate          string `json:"releaseDate,omitempty"`
 	BitDepth             int    `json:"bitDepth,omitempty"`
 	SampleRate           int    `json:"sampleRate,omitempty"`
 	Bitrate              int    `json:"bitrate,omitempty"` // kbps, for lossy formats (MP3, Opus, Vorbis)
 	Genre                string `json:"genre,omitempty"`
+	Composer             string `json:"composer,omitempty"`
+	Label                string `json:"label,omitempty"`
+	Copyright            string `json:"copyright,omitempty"`
 	Format               string `json:"format,omitempty"`
 	MetadataFromFilename bool   `json:"metadataFromFilename,omitempty"`
 }
@@ -365,9 +370,14 @@ func scanFLACFile(filePath string, result *LibraryScanResult, displayNameHint st
 	result.AlbumArtist = metadata.AlbumArtist
 	result.ISRC = metadata.ISRC
 	result.TrackNumber = metadata.TrackNumber
+	result.TotalTracks = metadata.TotalTracks
 	result.DiscNumber = metadata.DiscNumber
+	result.TotalDiscs = metadata.TotalDiscs
 	result.ReleaseDate = metadata.Date
 	result.Genre = metadata.Genre
+	result.Composer = metadata.Composer
+	result.Label = metadata.Label
+	result.Copyright = metadata.Copyright
 
 	quality, err := GetAudioQuality(filePath)
 	if err == nil {
@@ -397,12 +407,17 @@ func scanM4AFile(filePath string, result *LibraryScanResult, displayNameHint str
 		result.AlbumArtist = metadata.AlbumArtist
 		result.ISRC = metadata.ISRC
 		result.TrackNumber = metadata.TrackNumber
+		result.TotalTracks = metadata.TotalTracks
 		result.DiscNumber = metadata.DiscNumber
+		result.TotalDiscs = metadata.TotalDiscs
 		result.ReleaseDate = metadata.Date
 		if result.ReleaseDate == "" {
 			result.ReleaseDate = metadata.Year
 		}
 		result.Genre = metadata.Genre
+		result.Composer = metadata.Composer
+		result.Label = metadata.Label
+		result.Copyright = metadata.Copyright
 	}
 
 	quality, err := GetM4AQuality(filePath)
@@ -427,7 +442,9 @@ func scanMP3File(filePath string, result *LibraryScanResult, displayNameHint str
 	result.AlbumName = metadata.Album
 	result.AlbumArtist = metadata.AlbumArtist
 	result.TrackNumber = metadata.TrackNumber
+	result.TotalTracks = metadata.TotalTracks
 	result.DiscNumber = metadata.DiscNumber
+	result.TotalDiscs = metadata.TotalDiscs
 	result.Genre = metadata.Genre
 	if metadata.Date != "" {
 		result.ReleaseDate = metadata.Date
@@ -435,6 +452,9 @@ func scanMP3File(filePath string, result *LibraryScanResult, displayNameHint str
 		result.ReleaseDate = metadata.Year
 	}
 	result.ISRC = metadata.ISRC
+	result.Composer = metadata.Composer
+	result.Label = metadata.Label
+	result.Copyright = metadata.Copyright
 
 	quality, err := GetMP3Quality(filePath)
 	if err == nil {
@@ -464,9 +484,14 @@ func scanOggFile(filePath string, result *LibraryScanResult, displayNameHint str
 	result.AlbumArtist = metadata.AlbumArtist
 	result.ISRC = metadata.ISRC
 	result.TrackNumber = metadata.TrackNumber
+	result.TotalTracks = metadata.TotalTracks
 	result.DiscNumber = metadata.DiscNumber
+	result.TotalDiscs = metadata.TotalDiscs
 	result.Genre = metadata.Genre
 	result.ReleaseDate = metadata.Date
+	result.Composer = metadata.Composer
+	result.Label = metadata.Label
+	result.Copyright = metadata.Copyright
 
 	quality, err := GetOggQuality(filePath)
 	if err == nil {
@@ -501,13 +526,18 @@ func scanAPEFile(filePath string, result *LibraryScanResult, displayNameHint str
 	result.AlbumArtist = metadata.AlbumArtist
 	result.ISRC = metadata.ISRC
 	result.TrackNumber = metadata.TrackNumber
+	result.TotalTracks = metadata.TotalTracks
 	result.DiscNumber = metadata.DiscNumber
+	result.TotalDiscs = metadata.TotalDiscs
 	result.Genre = metadata.Genre
 	if metadata.Date != "" {
 		result.ReleaseDate = metadata.Date
 	} else {
 		result.ReleaseDate = metadata.Year
 	}
+	result.Composer = metadata.Composer
+	result.Label = metadata.Label
+	result.Copyright = metadata.Copyright
 
 	applyDefaultLibraryMetadata(filePath, displayNameHint, result)
 

go_backend/lyrics.go

@@ -385,8 +385,8 @@ func (c *LyricsClient) FetchLyricsAllSources(spotifyID, trackName, artistName st
 	primaryArtist := normalizeArtistName(artistName)
 	fetchOptions := GetLyricsFetchOptions()
 
-	extManager := GetExtensionManager()
-	var extensionProviders []*ExtensionProviderWrapper
+	extManager := getExtensionManager()
+	var extensionProviders []*extensionProviderWrapper
 	if extManager != nil {
 		extensionProviders = extManager.GetLyricsProviders()
 	}

go_backend/metadata.go

@@ -110,6 +110,7 @@ type Metadata struct {
 	TrackNumber   int
 	TotalTracks   int
 	DiscNumber    int
+	TotalDiscs    int
 	ISRC          string
 	Description   string
 	Lyrics        string
@@ -273,23 +274,23 @@ func ReadMetadata(filePath string) (*Metadata, error) {
 
 			trackNum := getComment(cmt, "TRACKNUMBER")
 			if trackNum != "" {
-				fmt.Sscanf(trackNum, "%d", &metadata.TrackNumber)
+				metadata.TrackNumber, metadata.TotalTracks = parseIndexPair(trackNum)
 			}
 			if metadata.TrackNumber == 0 {
 				trackNum = getComment(cmt, "TRACK")
 				if trackNum != "" {
-					fmt.Sscanf(trackNum, "%d", &metadata.TrackNumber)
+					metadata.TrackNumber, metadata.TotalTracks = parseIndexPair(trackNum)
 				}
 			}
 
 			discNum := getComment(cmt, "DISCNUMBER")
 			if discNum != "" {
-				fmt.Sscanf(discNum, "%d", &metadata.DiscNumber)
+				metadata.DiscNumber, metadata.TotalDiscs = parseIndexPair(discNum)
 			}
 			if metadata.DiscNumber == 0 {
 				discNum = getComment(cmt, "DISC")
 				if discNum != "" {
-					fmt.Sscanf(discNum, "%d", &metadata.DiscNumber)
+					metadata.DiscNumber, metadata.TotalDiscs = parseIndexPair(discNum)
 				}
 			}
 
@@ -403,26 +404,39 @@ func EditFlacFields(filePath string, fields map[string]string) error {
 		removeCommentKey(cmt, "ALBUM_ARTIST")
 	}
 
-	// Track/disc numbers: present + empty → clear; present + "0" → clear.
-	if v, ok := fields["track_number"]; ok {
-		trackNum := 0
-		if v != "" {
-			fmt.Sscanf(v, "%d", &trackNum)
+	// Track/disc numbers: present + empty → clear; when only totals are edited,
+	// preserve the current index number and rewrite the combined value.
+	if _, ok := fields["track_number"]; ok || fields["track_total"] != "" || hasMapKey(fields, "track_total") {
+		currentTrackNum, currentTotalTracks := parseIndexPair(getComment(cmt, "TRACKNUMBER"))
+		if currentTrackNum == 0 && currentTotalTracks == 0 {
+			currentTrackNum, currentTotalTracks = parseIndexPair(getComment(cmt, "TRACK"))
 		}
-		if trackNum > 0 {
-			setOrClearComment(cmt, "TRACKNUMBER", strconv.Itoa(trackNum))
+		if v, ok := fields["track_number"]; ok {
+			currentTrackNum = parsePositiveInt(v)
+		}
+		if v, ok := fields["track_total"]; ok {
+			currentTotalTracks = parsePositiveInt(v)
+		}
+		if currentTrackNum > 0 {
+			setOrClearComment(cmt, "TRACKNUMBER", formatIndexValue(currentTrackNum, currentTotalTracks))
 		} else {
 			removeCommentKey(cmt, "TRACKNUMBER")
 		}
 		removeCommentKey(cmt, "TRACK") // alias
 	}
-	if v, ok := fields["disc_number"]; ok {
-		discNum := 0
-		if v != "" {
-			fmt.Sscanf(v, "%d", &discNum)
+	if _, ok := fields["disc_number"]; ok || fields["disc_total"] != "" || hasMapKey(fields, "disc_total") {
+		currentDiscNum, currentTotalDiscs := parseIndexPair(getComment(cmt, "DISCNUMBER"))
+		if currentDiscNum == 0 && currentTotalDiscs == 0 {
+			currentDiscNum, currentTotalDiscs = parseIndexPair(getComment(cmt, "DISC"))
 		}
-		if discNum > 0 {
-			setOrClearComment(cmt, "DISCNUMBER", strconv.Itoa(discNum))
+		if v, ok := fields["disc_number"]; ok {
+			currentDiscNum = parsePositiveInt(v)
+		}
+		if v, ok := fields["disc_total"]; ok {
+			currentTotalDiscs = parsePositiveInt(v)
+		}
+		if currentDiscNum > 0 {
+			setOrClearComment(cmt, "DISCNUMBER", formatIndexValue(currentDiscNum, currentTotalDiscs))
 		} else {
 			removeCommentKey(cmt, "DISCNUMBER")
 		}
@@ -478,15 +492,11 @@ func writeVorbisMetadata(cmt *flacvorbis.MetaDataBlockVorbisComment, metadata Me
 	setComment(cmt, "DATE", metadata.Date)
 
 	if metadata.TrackNumber > 0 {
-		if metadata.TotalTracks > 0 {
-			setComment(cmt, "TRACKNUMBER", fmt.Sprintf("%d/%d", metadata.TrackNumber, metadata.TotalTracks))
-		} else {
-			setComment(cmt, "TRACKNUMBER", strconv.Itoa(metadata.TrackNumber))
-		}
+		setComment(cmt, "TRACKNUMBER", formatIndexValue(metadata.TrackNumber, metadata.TotalTracks))
 	}
 
 	if metadata.DiscNumber > 0 {
-		setComment(cmt, "DISCNUMBER", strconv.Itoa(metadata.DiscNumber))
+		setComment(cmt, "DISCNUMBER", formatIndexValue(metadata.DiscNumber, metadata.TotalDiscs))
 	}
 
 	if metadata.ISRC != "" {
@@ -953,9 +963,9 @@ func ReadM4ATags(filePath string) (*AudioMetadata, error) {
 		case "\xa9lyr":
 			metadata.Lyrics, _ = readM4ATextValue(f, header, fi.Size())
 		case "trkn":
-			metadata.TrackNumber, _ = readM4AIndexValue(f, header, fi.Size())
+			metadata.TrackNumber, metadata.TotalTracks, _ = readM4AIndexPair(f, header, fi.Size())
 		case "disk":
-			metadata.DiscNumber, _ = readM4AIndexValue(f, header, fi.Size())
+			metadata.DiscNumber, metadata.TotalDiscs, _ = readM4AIndexPair(f, header, fi.Size())
 		case "----":
 			name, value, freeformErr := readM4AFreeformValue(f, header, fi.Size())
 			if freeformErr == nil {
@@ -1150,6 +1160,41 @@ func readM4AIndexValue(f *os.File, parent atomHeader, fileSize int64) (int, erro
 	return int(binary.BigEndian.Uint16(payload[2:4])), nil
 }
 
+func readM4AIndexPair(f *os.File, parent atomHeader, fileSize int64) (int, int, error) {
+	payload, err := readM4ADataPayload(f, parent, fileSize)
+	if err != nil {
+		return 0, 0, err
+	}
+	if len(payload) < 6 {
+		return 0, 0, fmt.Errorf("index payload too short in %s", parent.typ)
+	}
+	return int(binary.BigEndian.Uint16(payload[2:4])), int(binary.BigEndian.Uint16(payload[4:6])), nil
+}
+
+func parsePositiveInt(value string) int {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return 0
+	}
+	n, _ := strconv.Atoi(value)
+	return n
+}
+
+func formatIndexValue(number, total int) string {
+	if number <= 0 {
+		return ""
+	}
+	if total > 0 {
+		return fmt.Sprintf("%d/%d", number, total)
+	}
+	return strconv.Itoa(number)
+}
+
+func hasMapKey(fields map[string]string, key string) bool {
+	_, ok := fields[key]
+	return ok
+}
+
 func readM4AFreeformValue(f *os.File, parent atomHeader, fileSize int64) (string, string, error) {
 	start := parent.offset + parent.headerSize
 	end := parent.offset + parent.size

go_backend/metadata_types.go

@@ -23,11 +23,13 @@ type TrackMetadata struct {
 	TrackNumber int    `json:"track_number"`
 	TotalTracks int    `json:"total_tracks,omitempty"`
 	DiscNumber  int    `json:"disc_number,omitempty"`
+	TotalDiscs  int    `json:"total_discs,omitempty"`
 	ExternalURL string `json:"external_urls"`
 	ISRC        string `json:"isrc"`
 	AlbumID     string `json:"album_id,omitempty"`
 	ArtistID    string `json:"artist_id,omitempty"`
 	AlbumType   string `json:"album_type,omitempty"`
+	Composer    string `json:"composer,omitempty"`
 }
 
 type AlbumTrackMetadata struct {
@@ -42,11 +44,13 @@ type AlbumTrackMetadata struct {
 	TrackNumber int    `json:"track_number"`
 	TotalTracks int    `json:"total_tracks,omitempty"`
 	DiscNumber  int    `json:"disc_number,omitempty"`
+	TotalDiscs  int    `json:"total_discs,omitempty"`
 	ExternalURL string `json:"external_urls"`
 	ISRC        string `json:"isrc"`
 	AlbumID     string `json:"album_id,omitempty"`
 	AlbumURL    string `json:"album_url,omitempty"`
 	AlbumType   string `json:"album_type,omitempty"`
+	Composer    string `json:"composer,omitempty"`
 }
 
 type AlbumInfoMetadata struct {

go_backend/qobuz.go

@@ -55,6 +55,7 @@ const (
 	qobuzTrackPlayBaseURL   = "https://play.qobuz.com/track/"
 	qobuzStoreBaseURL       = "https://www.qobuz.com/us-en"
 	qobuzDownloadAPIURL     = "https://dl.musicdl.me/qobuz/download"
+	qobuzZarzDownloadAPIURL = "https://api.zarz.moe/dl/qbz"
 	qobuzDabMusicAPIURL     = "https://dabmusic.xyz/api/stream?trackId="
 	qobuzDeebAPIURL         = "https://dab.yeet.su/api/stream?trackId="
 	qobuzAfkarAPIURL        = "https://qbz.afkarxyz.qzz.io/api/track/"
@@ -105,6 +106,10 @@ type QobuzTrack struct {
 		ID   int64  `json:"id"`
 		Name string `json:"name"`
 	} `json:"performer"`
+	Composer struct {
+		ID   int64  `json:"id"`
+		Name string `json:"name"`
+	} `json:"composer"`
 }
 
 type qobuzImageSet struct {
@@ -349,6 +354,7 @@ func qobuzTrackToTrackMetadata(track *QobuzTrack) TrackMetadata {
 		AlbumID:     qobuzPrefixedID(track.Album.ID),
 		ArtistID:    qobuzTrackArtistID(track),
 		AlbumType:   qobuzTrackAlbumType(track),
+		Composer:    strings.TrimSpace(track.Composer.Name),
 	}
 }
 
@@ -373,6 +379,7 @@ func qobuzTrackToAlbumTrackMetadata(track *QobuzTrack) AlbumTrackMetadata {
 		AlbumID:     qobuzPrefixedID(track.Album.ID),
 		AlbumURL:    fmt.Sprintf("https://play.qobuz.com/album/%s", strings.TrimSpace(track.Album.ID)),
 		AlbumType:   qobuzTrackAlbumType(track),
+		Composer:    strings.TrimSpace(track.Composer.Name),
 	}
 }
 
@@ -1030,6 +1037,7 @@ func (q *QobuzDownloader) GetAlbumMetadata(resourceID string) (*AlbumResponsePay
 	}
 
 	tracks := make([]AlbumTrackMetadata, 0, len(album.Tracks.Items))
+	totalDiscs := 0
 	for i := range album.Tracks.Items {
 		track := &album.Tracks.Items[i]
 		track.Album.ID = album.ID
@@ -1041,8 +1049,14 @@ func (q *QobuzDownloader) GetAlbumMetadata(resourceID string) (*AlbumResponsePay
 			Large:     album.Image.Large,
 		}
 		track.Album.TracksCount = album.TracksCount
+		if track.MediaNumber > totalDiscs {
+			totalDiscs = track.MediaNumber
+		}
 		tracks = append(tracks, qobuzTrackToAlbumTrackMetadata(track))
 	}
+	for i := range tracks {
+		tracks[i].TotalDiscs = totalDiscs
+	}
 
 	return &AlbumResponsePayload{
 		AlbumInfo: qobuzAlbumToAlbumInfo(album),
@@ -1126,6 +1140,7 @@ func (q *QobuzDownloader) GetArtistMetadata(resourceID string) (*ArtistResponseP
 func (q *QobuzDownloader) GetAvailableAPIs() []string {
 	return []string{
 		qobuzDownloadAPIURL,
+		qobuzZarzDownloadAPIURL,
 		qobuzDabMusicAPIURL,
 		qobuzDeebAPIURL,
 		qobuzAfkarAPIURL,
@@ -1147,6 +1162,7 @@ const (
 func (q *QobuzDownloader) GetAvailableProviders() []qobuzAPIProvider {
 	return []qobuzAPIProvider{
 		{Name: "musicdl", URL: qobuzDownloadAPIURL, Kind: qobuzAPIKindMusicDL},
+		{Name: "zarz", URL: qobuzZarzDownloadAPIURL, Kind: qobuzAPIKindMusicDL},
 		{Name: "dabmusic", URL: qobuzDabMusicAPIURL, Kind: qobuzAPIKindStandard},
 		{Name: "deeb", URL: qobuzDeebAPIURL, Kind: qobuzAPIKindStandard},
 		{Name: "qbz", URL: qobuzAfkarAPIURL, Kind: qobuzAPIKindStandard},
@@ -2793,10 +2809,12 @@ func downloadFromQobuz(req DownloadRequest) (QobuzDownloadResult, error) {
 		TrackNumber:   actualTrackNumber,
 		TotalTracks:   req.TotalTracks,
 		DiscNumber:    req.DiscNumber,
+		TotalDiscs:    req.TotalDiscs,
 		ISRC:          track.ISRC,
 		Genre:         req.Genre,
 		Label:         req.Label,
 		Copyright:     req.Copyright,
+		Composer:      req.Composer,
 	}
 
 	var coverData []byte

go_backend/qobuz_test.go

@@ -241,12 +241,13 @@ func TestExtractQobuzAlbumIDsFromArtistHTML(t *testing.T) {
 
 func TestQobuzAvailableProviders(t *testing.T) {
 	providers := NewQobuzDownloader().GetAvailableProviders()
-	if len(providers) != 5 {
-		t.Fatalf("expected 5 Qobuz providers, got %d", len(providers))
+	if len(providers) != 6 {
+		t.Fatalf("expected 6 Qobuz providers, got %d", len(providers))
 	}
 
 	want := map[string]string{
 		"musicdl":  qobuzAPIKindMusicDL,
+		"zarz":     qobuzAPIKindMusicDL,
 		"dabmusic": qobuzAPIKindStandard,
 		"deeb":     qobuzAPIKindStandard,
 		"qbz":      qobuzAPIKindStandard,
@@ -518,3 +519,37 @@ func TestQobuzTrackMatchesRequest_SongLinkBypassesArtistAndTitle(t *testing.T) {
 		t.Fatal("expected SongLink Qobuz source to bypass artist/title verification")
 	}
 }
+
+func TestQobuzTrackMetadataIncludesComposer(t *testing.T) {
+	track := &QobuzTrack{
+		ID:          40681594,
+		Title:       "Sign of the Times",
+		ISRC:        "USSM11703595",
+		Duration:    340,
+		TrackNumber: 1,
+		MediaNumber: 1,
+	}
+	track.Performer.ID = 729886
+	track.Performer.Name = "Harry Styles"
+	track.Composer.ID = 729886
+	track.Composer.Name = "Harry Styles"
+	track.Album.ID = "0886446451985"
+	track.Album.Title = "Harry Styles"
+	track.Album.ReleaseDate = "2017-05-12"
+	track.Album.TracksCount = 10
+	track.Album.ReleaseType = "album"
+	track.Album.ProductType = "album"
+	track.Album.Artist.ID = 729886
+	track.Album.Artist.Name = "Harry Styles"
+	track.Album.Artists = []qobuzArtistRef{{ID: 729886, Name: "Harry Styles"}}
+
+	trackMeta := qobuzTrackToTrackMetadata(track)
+	if trackMeta.Composer != "Harry Styles" {
+		t.Fatalf("track composer = %q", trackMeta.Composer)
+	}
+
+	albumTrackMeta := qobuzTrackToAlbumTrackMetadata(track)
+	if albumTrackMeta.Composer != "Harry Styles" {
+		t.Fatalf("album track composer = %q", albumTrackMeta.Composer)
+	}
+}

go_backend/tidal.go

@@ -1012,6 +1012,7 @@ func (t *TidalDownloader) GetAlbumMetadata(resourceID string) (*AlbumResponsePay
 	}
 
 	tracks := make([]AlbumTrackMetadata, 0, len(itemsModule.PagedList.Items))
+	totalDiscs := 0
 	for _, item := range itemsModule.PagedList.Items {
 		track := item.Item
 		track.Album.ID = headerModule.Album.ID
@@ -1019,8 +1020,14 @@ func (t *TidalDownloader) GetAlbumMetadata(resourceID string) (*AlbumResponsePay
 		track.Album.Cover = headerModule.Album.Cover
 		track.Album.ReleaseDate = headerModule.Album.ReleaseDate
 		track.Album.URL = headerModule.Album.URL
+		if track.VolumeNumber > totalDiscs {
+			totalDiscs = track.VolumeNumber
+		}
 		tracks = append(tracks, tidalTrackToAlbumTrackMetadata(&track))
 	}
+	for i := range tracks {
+		tracks[i].TotalDiscs = totalDiscs
+	}
 
 	return &AlbumResponsePayload{
 		AlbumInfo: tidalAlbumToAlbumInfo(&headerModule.Album),
@@ -2360,10 +2367,12 @@ func downloadFromTidal(req DownloadRequest) (TidalDownloadResult, error) {
 		TrackNumber:   actualTrackNumber,
 		TotalTracks:   req.TotalTracks,
 		DiscNumber:    actualDiscNumber,
+		TotalDiscs:    req.TotalDiscs,
 		ISRC:          track.ISRC,
 		Genre:         req.Genre,
 		Label:         req.Label,
 		Copyright:     req.Copyright,
+		Composer:      req.Composer,
 	}
 
 	var coverData []byte

ios/Runner/AppDelegate.swift

@@ -607,6 +607,13 @@ import Gobackend  // Import Go framework
             let response = GobackendGetProviderPriorityJSON(&error)
             if let error = error { throw error }
             return response
+
+        case "setDownloadFallbackExtensionIds":
+            let args = call.arguments as! [String: Any]
+            let extensionIdsJson = args["extension_ids"] as? String ?? ""
+            GobackendSetExtensionFallbackProviderIDsJSON(extensionIdsJson, &error)
+            if let error = error { throw error }
+            return nil
             
         case "setMetadataProviderPriority":
             let args = call.arguments as! [String: Any]

lib/constants/app_info.dart

@@ -3,8 +3,8 @@ import 'package:flutter/foundation.dart';
 /// App version and info constants
 /// Update version here only - all other files will reference this
 class AppInfo {
-  static const String version = '4.2.0';
-  static const String buildNumber = '121';
+  static const String version = '4.2.2';
+  static const String buildNumber = '123';
   static const String fullVersion = '$version+$buildNumber';
 
   /// Shows "Internal" in debug builds, actual version in release.

lib/l10n/app_localizations.dart

@@ -1738,6 +1738,24 @@ abstract class AppLocalizations {
   /// **'If a track is not available on the first provider, the app will automatically try the next one.'**
   String get providerPriorityInfo;
 
+  /// Section title for choosing which download extensions can be used as fallback providers
+  ///
+  /// In en, this message translates to:
+  /// **'Extension Fallback'**
+  String get providerPriorityFallbackExtensionsTitle;
+
+  /// Section description for extension fallback selection
+  ///
+  /// In en, this message translates to:
+  /// **'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.'**
+  String get providerPriorityFallbackExtensionsDescription;
+
+  /// Hint below the extension fallback selection list
+  ///
+  /// In en, this message translates to:
+  /// **'Only enabled extensions with download-provider capability are listed here.'**
+  String get providerPriorityFallbackExtensionsHint;
+
   /// Label for built-in providers (Tidal/Qobuz)
   ///
   /// In en, this message translates to:
@@ -2644,6 +2662,18 @@ abstract class AppLocalizations {
   /// **'Set download service order'**
   String get extensionsDownloadPrioritySubtitle;
 
+  /// Setting and page title for choosing which download extensions can be used during fallback
+  ///
+  /// In en, this message translates to:
+  /// **'Fallback Extensions'**
+  String get extensionsFallbackTitle;
+
+  /// Subtitle for download fallback extensions menu
+  ///
+  /// In en, this message translates to:
+  /// **'Choose which installed download extensions can be used as fallback'**
+  String get extensionsFallbackSubtitle;
+
   /// Empty state - no download providers
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_de.dart

@@ -940,6 +940,17 @@ class AppLocalizationsDe extends AppLocalizations {
   String get providerPriorityInfo =>
       'Wenn kein Titel bei dem ersten Anbieter nicht verfügbar ist, wird die App automatisch den nächsten versuchen.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Extension Fallback';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Only enabled extensions with download-provider capability are listed here.';
+
   @override
   String get providerBuiltIn => 'Integriert';
 
@@ -1438,6 +1449,13 @@ class AppLocalizationsDe extends AppLocalizations {
   String get extensionsDownloadPrioritySubtitle =>
       'Download-Service-Reihenfolge festlegen';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Choose which installed download extensions can be used as fallback';
+
   @override
   String get extensionsNoDownloadProvider =>
       'Keine Erweiterungen mit Download-Provider';

lib/l10n/app_localizations_en.dart

@@ -926,6 +926,17 @@ class AppLocalizationsEn extends AppLocalizations {
   String get providerPriorityInfo =>
       'If a track is not available on the first provider, the app will automatically try the next one.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Extension Fallback';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Only enabled extensions with download-provider capability are listed here.';
+
   @override
   String get providerBuiltIn => 'Built-in';
 
@@ -1415,6 +1426,13 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get extensionsDownloadPrioritySubtitle => 'Set download service order';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Choose which installed download extensions can be used as fallback';
+
   @override
   String get extensionsNoDownloadProvider =>
       'No extensions with download provider';

lib/l10n/app_localizations_es.dart

@@ -926,6 +926,17 @@ class AppLocalizationsEs extends AppLocalizations {
   String get providerPriorityInfo =>
       'If a track is not available on the first provider, the app will automatically try the next one.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Extension Fallback';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Only enabled extensions with download-provider capability are listed here.';
+
   @override
   String get providerBuiltIn => 'Built-in';
 
@@ -1415,6 +1426,13 @@ class AppLocalizationsEs extends AppLocalizations {
   @override
   String get extensionsDownloadPrioritySubtitle => 'Set download service order';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Choose which installed download extensions can be used as fallback';
+
   @override
   String get extensionsNoDownloadProvider =>
       'No extensions with download provider';

lib/l10n/app_localizations_fr.dart

@@ -928,6 +928,17 @@ class AppLocalizationsFr extends AppLocalizations {
   String get providerPriorityInfo =>
       'If a track is not available on the first provider, the app will automatically try the next one.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Extension Fallback';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Only enabled extensions with download-provider capability are listed here.';
+
   @override
   String get providerBuiltIn => 'Built-in';
 
@@ -1417,6 +1428,13 @@ class AppLocalizationsFr extends AppLocalizations {
   @override
   String get extensionsDownloadPrioritySubtitle => 'Set download service order';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Choose which installed download extensions can be used as fallback';
+
   @override
   String get extensionsNoDownloadProvider =>
       'No extensions with download provider';

lib/l10n/app_localizations_hi.dart

@@ -926,6 +926,17 @@ class AppLocalizationsHi extends AppLocalizations {
   String get providerPriorityInfo =>
       'If a track is not available on the first provider, the app will automatically try the next one.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Extension Fallback';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Only enabled extensions with download-provider capability are listed here.';
+
   @override
   String get providerBuiltIn => 'Built-in';
 
@@ -1415,6 +1426,13 @@ class AppLocalizationsHi extends AppLocalizations {
   @override
   String get extensionsDownloadPrioritySubtitle => 'Set download service order';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Choose which installed download extensions can be used as fallback';
+
   @override
   String get extensionsNoDownloadProvider =>
       'No extensions with download provider';

lib/l10n/app_localizations_id.dart

@@ -930,6 +930,17 @@ class AppLocalizationsId extends AppLocalizations {
   String get providerPriorityInfo =>
       'Jika lagu tidak tersedia di provider pertama, aplikasi akan otomatis mencoba yang berikutnya.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Fallback Ekstensi';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Pilih ekstensi unduhan terpasang mana yang boleh dipakai saat fallback otomatis. Provider bawaan tetap mengikuti urutan prioritas di atas.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Hanya ekstensi aktif dengan kemampuan download provider yang ditampilkan di sini.';
+
   @override
   String get providerBuiltIn => 'Bawaan';
 
@@ -1423,6 +1434,13 @@ class AppLocalizationsId extends AppLocalizations {
   String get extensionsDownloadPrioritySubtitle =>
       'Atur urutan layanan unduhan';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Pilih ekstensi unduhan terpasang yang boleh dipakai saat fallback';
+
   @override
   String get extensionsNoDownloadProvider =>
       'Tidak ada ekstensi dengan provider unduhan';

lib/l10n/app_localizations_ja.dart

@@ -920,6 +920,17 @@ class AppLocalizationsJa extends AppLocalizations {
   String get providerPriorityInfo =>
       'If a track is not available on the first provider, the app will automatically try the next one.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Extension Fallback';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Only enabled extensions with download-provider capability are listed here.';
+
   @override
   String get providerBuiltIn => '内蔵';
 
@@ -1409,6 +1420,13 @@ class AppLocalizationsJa extends AppLocalizations {
   @override
   String get extensionsDownloadPrioritySubtitle => 'ダウンロードサービスの順序を設定';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Choose which installed download extensions can be used as fallback';
+
   @override
   String get extensionsNoDownloadProvider => 'ダウンロードプロバイダーの拡張はありません';
 

lib/l10n/app_localizations_ko.dart

@@ -908,6 +908,17 @@ class AppLocalizationsKo extends AppLocalizations {
   String get providerPriorityInfo =>
       'If a track is not available on the first provider, the app will automatically try the next one.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Extension Fallback';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Only enabled extensions with download-provider capability are listed here.';
+
   @override
   String get providerBuiltIn => 'Built-in';
 
@@ -1395,6 +1406,13 @@ class AppLocalizationsKo extends AppLocalizations {
   @override
   String get extensionsDownloadPrioritySubtitle => 'Set download service order';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Choose which installed download extensions can be used as fallback';
+
   @override
   String get extensionsNoDownloadProvider =>
       'No extensions with download provider';

lib/l10n/app_localizations_nl.dart

@@ -926,6 +926,17 @@ class AppLocalizationsNl extends AppLocalizations {
   String get providerPriorityInfo =>
       'If a track is not available on the first provider, the app will automatically try the next one.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Extension Fallback';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Only enabled extensions with download-provider capability are listed here.';
+
   @override
   String get providerBuiltIn => 'Built-in';
 
@@ -1415,6 +1426,13 @@ class AppLocalizationsNl extends AppLocalizations {
   @override
   String get extensionsDownloadPrioritySubtitle => 'Set download service order';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Choose which installed download extensions can be used as fallback';
+
   @override
   String get extensionsNoDownloadProvider =>
       'No extensions with download provider';

lib/l10n/app_localizations_pt.dart

@@ -926,6 +926,17 @@ class AppLocalizationsPt extends AppLocalizations {
   String get providerPriorityInfo =>
       'If a track is not available on the first provider, the app will automatically try the next one.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Extension Fallback';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Only enabled extensions with download-provider capability are listed here.';
+
   @override
   String get providerBuiltIn => 'Built-in';
 
@@ -1415,6 +1426,13 @@ class AppLocalizationsPt extends AppLocalizations {
   @override
   String get extensionsDownloadPrioritySubtitle => 'Set download service order';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Choose which installed download extensions can be used as fallback';
+
   @override
   String get extensionsNoDownloadProvider =>
       'No extensions with download provider';

lib/l10n/app_localizations_ru.dart

@@ -940,6 +940,17 @@ class AppLocalizationsRu extends AppLocalizations {
   String get providerPriorityInfo =>
       'Если трек не доступен у первого провайдера, приложение автоматически попробует следующий.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Extension Fallback';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Only enabled extensions with download-provider capability are listed here.';
+
   @override
   String get providerBuiltIn => 'Встроенные';
 
@@ -1439,6 +1450,13 @@ class AppLocalizationsRu extends AppLocalizations {
   String get extensionsDownloadPrioritySubtitle =>
       'Установка порядок сервисов скачивания';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Choose which installed download extensions can be used as fallback';
+
   @override
   String get extensionsNoDownloadProvider =>
       'Нет расширений с провайдером загрузки';

lib/l10n/app_localizations_tr.dart

@@ -931,6 +931,17 @@ class AppLocalizationsTr extends AppLocalizations {
   String get providerPriorityInfo =>
       'Eğer bir şarkı ilk hizmette mevcut değilse uygulama otomatik olarak bir sonrakini deneyecektir.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Extension Fallback';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Only enabled extensions with download-provider capability are listed here.';
+
   @override
   String get providerBuiltIn => 'Dahili';
 
@@ -1421,6 +1432,13 @@ class AppLocalizationsTr extends AppLocalizations {
   @override
   String get extensionsDownloadPrioritySubtitle => 'Set download service order';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Choose which installed download extensions can be used as fallback';
+
   @override
   String get extensionsNoDownloadProvider =>
       'No extensions with download provider';

lib/l10n/app_localizations_zh.dart

@@ -926,6 +926,17 @@ class AppLocalizationsZh extends AppLocalizations {
   String get providerPriorityInfo =>
       'If a track is not available on the first provider, the app will automatically try the next one.';
 
+  @override
+  String get providerPriorityFallbackExtensionsTitle => 'Extension Fallback';
+
+  @override
+  String get providerPriorityFallbackExtensionsDescription =>
+      'Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.';
+
+  @override
+  String get providerPriorityFallbackExtensionsHint =>
+      'Only enabled extensions with download-provider capability are listed here.';
+
   @override
   String get providerBuiltIn => 'Built-in';
 
@@ -1415,6 +1426,13 @@ class AppLocalizationsZh extends AppLocalizations {
   @override
   String get extensionsDownloadPrioritySubtitle => 'Set download service order';
 
+  @override
+  String get extensionsFallbackTitle => 'Fallback Extensions';
+
+  @override
+  String get extensionsFallbackSubtitle =>
+      'Choose which installed download extensions can be used as fallback';
+
   @override
   String get extensionsNoDownloadProvider =>
       'No extensions with download provider';

lib/l10n/arb/app_en.arb

@@ -1203,6 +1203,18 @@
   "@providerPriorityInfo": {
     "description": "Info tip about fallback behavior"
   },
+  "providerPriorityFallbackExtensionsTitle": "Extension Fallback",
+  "@providerPriorityFallbackExtensionsTitle": {
+    "description": "Section title for choosing which download extensions can be used as fallback providers"
+  },
+  "providerPriorityFallbackExtensionsDescription": "Choose which installed download extensions can be used during automatic fallback. Built-in providers still follow the priority order above.",
+  "@providerPriorityFallbackExtensionsDescription": {
+    "description": "Section description for extension fallback selection"
+  },
+  "providerPriorityFallbackExtensionsHint": "Only enabled extensions with download-provider capability are listed here.",
+  "@providerPriorityFallbackExtensionsHint": {
+    "description": "Hint below the extension fallback selection list"
+  },
   "providerBuiltIn": "Built-in",
   "@providerBuiltIn": {
     "description": "Label for built-in providers (Tidal/Qobuz)"
@@ -1857,6 +1869,14 @@
   "@extensionsDownloadPrioritySubtitle": {
     "description": "Subtitle for download priority"
   },
+  "extensionsFallbackTitle": "Fallback Extensions",
+  "@extensionsFallbackTitle": {
+    "description": "Setting and page title for choosing which download extensions can be used during fallback"
+  },
+  "extensionsFallbackSubtitle": "Choose which installed download extensions can be used as fallback",
+  "@extensionsFallbackSubtitle": {
+    "description": "Subtitle for download fallback extensions menu"
+  },
   "extensionsNoDownloadProvider": "No extensions with download provider",
   "@extensionsNoDownloadProvider": {
     "description": "Empty state - no download providers"

lib/l10n/arb/app_id.arb

@@ -1119,6 +1119,18 @@
   "@providerPriorityInfo": {
     "description": "Info tip about fallback behavior"
   },
+  "providerPriorityFallbackExtensionsTitle": "Fallback Ekstensi",
+  "@providerPriorityFallbackExtensionsTitle": {
+    "description": "Section title for choosing which download extensions can be used as fallback providers"
+  },
+  "providerPriorityFallbackExtensionsDescription": "Pilih ekstensi unduhan terpasang mana yang boleh dipakai saat fallback otomatis. Provider bawaan tetap mengikuti urutan prioritas di atas.",
+  "@providerPriorityFallbackExtensionsDescription": {
+    "description": "Section description for extension fallback selection"
+  },
+  "providerPriorityFallbackExtensionsHint": "Hanya ekstensi aktif dengan kemampuan download provider yang ditampilkan di sini.",
+  "@providerPriorityFallbackExtensionsHint": {
+    "description": "Hint below the extension fallback selection list"
+  },
   "providerBuiltIn": "Bawaan",
   "@providerBuiltIn": {
     "description": "Label for built-in providers (Tidal/Qobuz)"
@@ -1713,6 +1725,14 @@
   "@extensionsDownloadPrioritySubtitle": {
     "description": "Subtitle for download priority"
   },
+  "extensionsFallbackTitle": "Fallback Extensions",
+  "@extensionsFallbackTitle": {
+    "description": "Setting and page title for choosing which download extensions can be used during fallback"
+  },
+  "extensionsFallbackSubtitle": "Pilih ekstensi unduhan terpasang yang boleh dipakai saat fallback",
+  "@extensionsFallbackSubtitle": {
+    "description": "Subtitle for download fallback extensions menu"
+  },
   "extensionsNoDownloadProvider": "Tidak ada ekstensi dengan provider unduhan",
   "@extensionsNoDownloadProvider": {
     "description": "Empty state - no download providers"

lib/models/settings.dart

@@ -33,6 +33,7 @@ class AppSettings {
   final bool askQualityBeforeDownload;
   final bool enableLogging;
   final bool useExtensionProviders;
+  final List<String>? downloadFallbackExtensionIds;
   final String? searchProvider;
   final String? homeFeedProvider;
   final bool separateSingles;
@@ -108,6 +109,7 @@ class AppSettings {
     this.askQualityBeforeDownload = true,
     this.enableLogging = false,
     this.useExtensionProviders = true,
+    this.downloadFallbackExtensionIds,
     this.searchProvider,
     this.homeFeedProvider,
     this.separateSingles = false,
@@ -170,6 +172,8 @@ class AppSettings {
     bool? askQualityBeforeDownload,
     bool? enableLogging,
     bool? useExtensionProviders,
+    List<String>? downloadFallbackExtensionIds,
+    bool clearDownloadFallbackExtensionIds = false,
     String? searchProvider,
     bool clearSearchProvider = false,
     String? homeFeedProvider,
@@ -232,6 +236,9 @@ class AppSettings {
       enableLogging: enableLogging ?? this.enableLogging,
       useExtensionProviders:
           useExtensionProviders ?? this.useExtensionProviders,
+      downloadFallbackExtensionIds: clearDownloadFallbackExtensionIds
+          ? null
+          : (downloadFallbackExtensionIds ?? this.downloadFallbackExtensionIds),
       searchProvider: clearSearchProvider
           ? null
           : (searchProvider ?? this.searchProvider),

lib/models/settings.g.dart

@@ -35,6 +35,10 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
   askQualityBeforeDownload: json['askQualityBeforeDownload'] as bool? ?? true,
   enableLogging: json['enableLogging'] as bool? ?? false,
   useExtensionProviders: json['useExtensionProviders'] as bool? ?? true,
+  downloadFallbackExtensionIds:
+      (json['downloadFallbackExtensionIds'] as List<dynamic>?)
+          ?.map((e) => e as String)
+          .toList(),
   searchProvider: json['searchProvider'] as String?,
   homeFeedProvider: json['homeFeedProvider'] as String?,
   separateSingles: json['separateSingles'] as bool? ?? false,
@@ -105,6 +109,7 @@ Map<String, dynamic> _$AppSettingsToJson(
   'askQualityBeforeDownload': instance.askQualityBeforeDownload,
   'enableLogging': instance.enableLogging,
   'useExtensionProviders': instance.useExtensionProviders,
+  'downloadFallbackExtensionIds': instance.downloadFallbackExtensionIds,
   'searchProvider': instance.searchProvider,
   'homeFeedProvider': instance.homeFeedProvider,
   'separateSingles': instance.separateSingles,

lib/models/track.dart

@@ -16,12 +16,14 @@ class Track {
   final int duration;
   final int? trackNumber;
   final int? discNumber;
+  final int? totalDiscs;
   final String? releaseDate;
   final String? deezerId;
   final ServiceAvailability? availability;
   final String? source;
   final String? albumType;
   final int? totalTracks;
+  final String? composer;
   final String? itemType;
 
   const Track({
@@ -37,12 +39,14 @@ class Track {
     required this.duration,
     this.trackNumber,
     this.discNumber,
+    this.totalDiscs,
     this.releaseDate,
     this.deezerId,
     this.availability,
     this.source,
     this.albumType,
     this.totalTracks,
+    this.composer,
     this.itemType,
   });
 

lib/models/track.g.dart

@@ -19,6 +19,7 @@ Track _$TrackFromJson(Map<String, dynamic> json) => Track(
   duration: (json['duration'] as num).toInt(),
   trackNumber: (json['trackNumber'] as num?)?.toInt(),
   discNumber: (json['discNumber'] as num?)?.toInt(),
+  totalDiscs: (json['totalDiscs'] as num?)?.toInt(),
   releaseDate: json['releaseDate'] as String?,
   deezerId: json['deezerId'] as String?,
   availability: json['availability'] == null
@@ -29,6 +30,7 @@ Track _$TrackFromJson(Map<String, dynamic> json) => Track(
   source: json['source'] as String?,
   albumType: json['albumType'] as String?,
   totalTracks: (json['totalTracks'] as num?)?.toInt(),
+  composer: json['composer'] as String?,
   itemType: json['itemType'] as String?,
 );
 
@@ -45,12 +47,14 @@ Map<String, dynamic> _$TrackToJson(Track instance) => <String, dynamic>{
   'duration': instance.duration,
   'trackNumber': instance.trackNumber,
   'discNumber': instance.discNumber,
+  'totalDiscs': instance.totalDiscs,
   'releaseDate': instance.releaseDate,
   'deezerId': instance.deezerId,
   'availability': instance.availability,
   'source': instance.source,
   'albumType': instance.albumType,
   'totalTracks': instance.totalTracks,
+  'composer': instance.composer,
   'itemType': instance.itemType,
 };
 

lib/providers/extension_provider.dart

@@ -820,7 +820,7 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
       }
     }
 
-    for (final provider in const ['tidal', 'qobuz', 'deezer']) {
+    for (final provider in const ['tidal', 'qobuz']) {
       if (!result.contains(provider)) {
         result.add(provider);
       }
@@ -896,7 +896,7 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
   }
 
   List<String> getAllDownloadProviders() {
-    final providers = ['tidal', 'qobuz', 'deezer'];
+    final providers = ['tidal', 'qobuz'];
     for (final ext in state.extensions) {
       if (ext.enabled && ext.hasDownloadProvider) {
         providers.add(ext.id);

lib/providers/settings_provider.dart

@@ -12,7 +12,7 @@ import 'package:spotiflac_android/utils/logger.dart';
 
 const _settingsKey = 'app_settings';
 const _migrationVersionKey = 'settings_migration_version';
-const _currentMigrationVersion = 9;
+const _currentMigrationVersion = 10;
 const _spotifyClientSecretKey = 'spotify_client_secret';
 final _log = AppLogger('SettingsProvider');
 
@@ -35,9 +35,19 @@ class SettingsNotifier extends Notifier<AppSettings> {
     final prefs = await _prefs;
     final json = prefs.getString(_settingsKey);
     if (json != null) {
-      state = AppSettings.fromJson(
+      final loaded = AppSettings.fromJson(
         Map<String, dynamic>.from(jsonDecode(json) as Map),
       );
+      final sanitizedDownloadFallbackExtensionIds =
+          _sanitizeDownloadFallbackExtensionIds(
+            loaded.downloadFallbackExtensionIds,
+          );
+      state = loaded.copyWith(
+        downloadFallbackExtensionIds: sanitizedDownloadFallbackExtensionIds,
+        clearDownloadFallbackExtensionIds:
+            loaded.downloadFallbackExtensionIds != null &&
+            sanitizedDownloadFallbackExtensionIds == null,
+      );
 
       await _runMigrations(prefs);
       await _normalizeIosDownloadDirectoryIfNeeded();
@@ -50,6 +60,7 @@ class SettingsNotifier extends Notifier<AppSettings> {
 
     _syncLyricsSettingsToBackend();
     _syncNetworkCompatibilitySettingsToBackend();
+    _syncExtensionFallbackSettingsToBackend();
   }
 
   void _syncLyricsSettingsToBackend() {
@@ -83,6 +94,16 @@ class SettingsNotifier extends Notifier<AppSettings> {
     });
   }
 
+  void _syncExtensionFallbackSettingsToBackend() {
+    if (!PlatformBridge.supportsCoreBackend) return;
+
+    PlatformBridge.setDownloadFallbackExtensionIds(
+      state.downloadFallbackExtensionIds,
+    ).catchError((Object e) {
+      _log.w('Failed to sync extension fallback settings to backend: $e');
+    });
+  }
+
   Future<void> _runMigrations(SharedPreferences prefs) async {
     final lastMigration = prefs.getInt(_migrationVersionKey) ?? 0;
 
@@ -111,8 +132,9 @@ class SettingsNotifier extends Notifier<AppSettings> {
         );
       }
       state = state.copyWith(lastSeenVersion: AppInfo.version);
-      // Migration 7: YouTube is no longer a built-in service — reset to Tidal
-      if (state.defaultService == 'youtube') {
+      // Migration 7/10: retired built-in services reset back to Tidal
+      if (state.defaultService == 'youtube' ||
+          state.defaultService == 'deezer') {
         state = state.copyWith(defaultService: 'tidal');
       }
       await prefs.setInt(_migrationVersionKey, _currentMigrationVersion);
@@ -172,6 +194,22 @@ class SettingsNotifier extends Notifier<AppSettings> {
     await _saveSettings();
   }
 
+  List<String>? _sanitizeDownloadFallbackExtensionIds(List<String>? ids) {
+    if (ids == null) {
+      return null;
+    }
+
+    final result = <String>[];
+    for (final id in ids) {
+      final normalized = id.trim();
+      if (normalized.isEmpty || result.contains(normalized)) {
+        continue;
+      }
+      result.add(normalized);
+    }
+    return result;
+  }
+
   Future<void> _cleanupRetiredSpotifySettings() async {
     final storedSecret = await _secureStorage.read(
       key: _spotifyClientSecretKey,
@@ -390,6 +428,17 @@ class SettingsNotifier extends Notifier<AppSettings> {
     _saveSettings();
   }
 
+  void setDownloadFallbackExtensionIds(List<String>? extensionIds) {
+    final sanitized = _sanitizeDownloadFallbackExtensionIds(extensionIds);
+    state = state.copyWith(
+      downloadFallbackExtensionIds: sanitized,
+      clearDownloadFallbackExtensionIds:
+          extensionIds == null && state.downloadFallbackExtensionIds != null,
+    );
+    _saveSettings();
+    _syncExtensionFallbackSettingsToBackend();
+  }
+
   void setSeparateSingles(bool enabled) {
     state = state.copyWith(separateSingles: enabled);
     _saveSettings();

lib/providers/track_provider.dart

@@ -906,9 +906,11 @@ class TrackNotifier extends Notifier<TrackState> {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date'] as String?,
-      albumType: data['album_type'] as String?,
+      albumType: normalizeOptionalString(data['album_type']?.toString()),
       totalTracks: data['total_tracks'] as int?,
+      composer: data['composer']?.toString(),
     );
   }
 
@@ -939,10 +941,12 @@ class TrackNotifier extends Notifier<TrackState> {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
       totalTracks: data['total_tracks'] as int?,
       source: effectiveSource,
-      albumType: data['album_type']?.toString(),
+      albumType: normalizeOptionalString(data['album_type']?.toString()),
+      composer: data['composer']?.toString(),
       itemType: itemType,
     );
   }

lib/screens/album_screen.dart

@@ -75,6 +75,8 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
   String? _error;
   bool _showTitleInAppBar = false;
   String? _artistId;
+  String? _albumType;
+  int? _albumTotalTracks;
   final ScrollController _scrollController = ScrollController();
 
   @override
@@ -112,6 +114,8 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
       _tracks = _AlbumCache.get(widget.albumId);
     }
     _artistId = widget.artistId;
+    _albumType = _tracks?.firstOrNull?.albumType;
+    _albumTotalTracks = _tracks?.firstOrNull?.totalTracks;
 
     if (_tracks == null || _tracks!.isEmpty) {
       _fetchTracks();
@@ -179,13 +183,22 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
           deezerAlbumId,
         );
         final trackList = metadata['track_list'] as List<dynamic>;
-        final tracks = trackList
-            .map((t) => _parseTrack(t as Map<String, dynamic>))
-            .toList();
-
         final albumInfo = metadata['album_info'] as Map<String, dynamic>?;
         final artistId = (albumInfo?['artist_id'] ?? albumInfo?['artistId'])
             ?.toString();
+        final albumType = normalizeOptionalString(
+          albumInfo?['album_type']?.toString(),
+        );
+        final totalTracks = albumInfo?['total_tracks'] as int?;
+        final tracks = trackList
+            .map(
+              (t) => _parseTrack(
+                t as Map<String, dynamic>,
+                albumTypeFallback: albumType,
+                totalTracksFallback: totalTracks,
+              ),
+            )
+            .toList();
 
         _AlbumCache.set(widget.albumId, tracks);
 
@@ -193,6 +206,8 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
           setState(() {
             _tracks = tracks;
             _artistId = artistId;
+            _albumType = albumType;
+            _albumTotalTracks = totalTracks;
             _isLoading = false;
           });
         }
@@ -204,13 +219,22 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
           qobuzAlbumId,
         );
         final trackList = metadata['track_list'] as List<dynamic>;
-        final tracks = trackList
-            .map((t) => _parseTrack(t as Map<String, dynamic>))
-            .toList();
-
         final albumInfo = metadata['album_info'] as Map<String, dynamic>?;
         final artistId = (albumInfo?['artist_id'] ?? albumInfo?['artistId'])
             ?.toString();
+        final albumType = normalizeOptionalString(
+          albumInfo?['album_type']?.toString(),
+        );
+        final totalTracks = albumInfo?['total_tracks'] as int?;
+        final tracks = trackList
+            .map(
+              (t) => _parseTrack(
+                t as Map<String, dynamic>,
+                albumTypeFallback: albumType,
+                totalTracksFallback: totalTracks,
+              ),
+            )
+            .toList();
 
         _AlbumCache.set(widget.albumId, tracks);
 
@@ -218,6 +242,8 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
           setState(() {
             _tracks = tracks;
             _artistId = artistId;
+            _albumType = albumType;
+            _albumTotalTracks = totalTracks;
             _isLoading = false;
           });
         }
@@ -229,13 +255,22 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
           tidalAlbumId,
         );
         final trackList = metadata['track_list'] as List<dynamic>;
-        final tracks = trackList
-            .map((t) => _parseTrack(t as Map<String, dynamic>))
-            .toList();
-
         final albumInfo = metadata['album_info'] as Map<String, dynamic>?;
         final artistId = (albumInfo?['artist_id'] ?? albumInfo?['artistId'])
             ?.toString();
+        final albumType = normalizeOptionalString(
+          albumInfo?['album_type']?.toString(),
+        );
+        final totalTracks = albumInfo?['total_tracks'] as int?;
+        final tracks = trackList
+            .map(
+              (t) => _parseTrack(
+                t as Map<String, dynamic>,
+                albumTypeFallback: albumType,
+                totalTracksFallback: totalTracks,
+              ),
+            )
+            .toList();
 
         _AlbumCache.set(widget.albumId, tracks);
 
@@ -243,6 +278,8 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
           setState(() {
             _tracks = tracks;
             _artistId = artistId;
+            _albumType = albumType;
+            _albumTotalTracks = totalTracks;
             _isLoading = false;
           });
         }
@@ -255,13 +292,22 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
         }
 
         final trackList = result['tracks'] as List<dynamic>;
-        final tracks = trackList
-            .map((t) => _parseTrack(t as Map<String, dynamic>))
-            .toList();
-
         final albumInfo = result['album'] as Map<String, dynamic>?;
         final artistId = (albumInfo?['artist_id'] ?? albumInfo?['artistId'])
             ?.toString();
+        final albumType = normalizeOptionalString(
+          albumInfo?['album_type']?.toString(),
+        );
+        final totalTracks = albumInfo?['total_tracks'] as int?;
+        final tracks = trackList
+            .map(
+              (t) => _parseTrack(
+                t as Map<String, dynamic>,
+                albumTypeFallback: albumType,
+                totalTracksFallback: totalTracks,
+              ),
+            )
+            .toList();
 
         _AlbumCache.set(widget.albumId, tracks);
 
@@ -269,6 +315,8 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
           setState(() {
             _tracks = tracks;
             _artistId = artistId;
+            _albumType = albumType;
+            _albumTotalTracks = totalTracks;
             _isLoading = false;
           });
         }
@@ -284,7 +332,11 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
     }
   }
 
-  Track _parseTrack(Map<String, dynamic> data) {
+  Track _parseTrack(
+    Map<String, dynamic> data, {
+    String? albumTypeFallback,
+    int? totalTracksFallback,
+  }) {
     return Track(
       id: data['spotify_id'] as String? ?? '',
       name: data['name'] as String? ?? '',
@@ -299,9 +351,17 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
       duration: ((data['duration_ms'] as int? ?? 0) / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date'] as String?,
-      albumType: data['album_type'] as String?,
-      totalTracks: data['total_tracks'] as int?,
+      albumType:
+          normalizeOptionalString(data['album_type']?.toString()) ??
+          albumTypeFallback ??
+          _albumType,
+      totalTracks:
+          data['total_tracks'] as int? ??
+          totalTracksFallback ??
+          _albumTotalTracks,
+      composer: data['composer']?.toString(),
     );
   }
 
@@ -311,7 +371,6 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
     }
     if (widget.albumId.startsWith('tidal:')) return 'tidal';
     if (widget.albumId.startsWith('qobuz:')) return 'qobuz';
-    if (widget.albumId.startsWith('deezer:')) return 'deezer';
     return null;
   }
 

lib/screens/artist_screen.dart

@@ -159,7 +159,6 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
     }
     if (widget.artistId.startsWith('tidal:')) return 'tidal';
     if (widget.artistId.startsWith('qobuz:')) return 'qobuz';
-    if (widget.artistId.startsWith('deezer:')) return 'deezer';
     return null;
   }
 
@@ -410,9 +409,13 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
-      albumType: data['album_type']?.toString() ?? album?.albumType,
+      albumType:
+          normalizeOptionalString(data['album_type']?.toString()) ??
+          album?.albumType,
       totalTracks: data['total_tracks'] as int? ?? album?.totalTracks,
+      composer: data['composer']?.toString(),
       source: data['provider_id']?.toString() ?? widget.extensionId,
     );
   }
@@ -1055,9 +1058,10 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
       );
       if (result != null && result['tracks'] != null) {
         final tracksList = result['tracks'] as List<dynamic>;
-        return tracksList
+        final parsedTracks = tracksList
             .map((t) => _parseTrack(t as Map<String, dynamic>, album: album))
             .toList();
+        return parsedTracks;
       }
     } else if (album.id.startsWith('deezer:')) {
       final deezerId = album.id.replaceFirst('deezer:', '');
@@ -1129,9 +1133,11 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
       trackNumber:
           data['track_position'] as int? ?? data['track_number'] as int?,
       discNumber: data['disk_number'] as int? ?? data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: album.releaseDate,
       albumType: album.albumType,
       totalTracks: album.totalTracks,
+      composer: data['composer']?.toString(),
     );
   }
 
@@ -1930,6 +1936,8 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
             albumId: album.id,
             albumName: album.name,
             coverUrl: album.coverUrl,
+            initialAlbumType: album.albumType,
+            initialTotalTracks: album.totalTracks,
           ),
         ),
       );

lib/screens/downloaded_album_screen.dart

@@ -299,7 +299,11 @@ class _DownloadedAlbumScreenState extends ConsumerState<DownloadedAlbumScreen> {
     });
   }
 
-  Future<void> _navigateToMetadataScreen(DownloadHistoryItem item) async {
+  Future<void> _navigateToMetadataScreen(
+    DownloadHistoryItem item, {
+    required List<DownloadHistoryItem> navigationItems,
+    required int navigationIndex,
+  }) async {
     final navigator = Navigator.of(context);
     _precacheCover(item.coverUrl);
     final beforeModTime =
@@ -309,7 +313,13 @@ class _DownloadedAlbumScreenState extends ConsumerState<DownloadedAlbumScreen> {
     if (!mounted) return;
 
     final result = await navigator.push(
-      slidePageRoute<bool>(page: TrackMetadataScreen(item: item)),
+      slidePageRoute<bool>(
+        page: TrackMetadataScreen(
+          item: item,
+          historyNavigationItems: navigationItems,
+          navigationIndex: navigationIndex,
+        ),
+      ),
     );
     await DownloadedEmbeddedCoverResolver.scheduleRefreshForPath(
       item.filePath,
@@ -691,7 +701,13 @@ class _DownloadedAlbumScreenState extends ConsumerState<DownloadedAlbumScreen> {
             key: ValueKey(track.id),
             child: StaggeredListItem(
               index: index,
-              child: _buildTrackItem(context, colorScheme, track),
+              child: _buildTrackItem(
+                context,
+                colorScheme,
+                track,
+                tracks,
+                index,
+              ),
             ),
           );
         }, childCount: tracks.length),
@@ -709,12 +725,19 @@ class _DownloadedAlbumScreenState extends ConsumerState<DownloadedAlbumScreen> {
       children.add(_buildDiscSeparator(context, colorScheme, discNumber));
 
       for (final track in discTracks) {
+        final navigationIndex = tracks.indexOf(track);
         children.add(
           KeyedSubtree(
             key: ValueKey(track.id),
             child: StaggeredListItem(
               index: revealIndex++,
-              child: _buildTrackItem(context, colorScheme, track),
+              child: _buildTrackItem(
+                context,
+                colorScheme,
+                track,
+                tracks,
+                navigationIndex,
+              ),
             ),
           ),
         );
@@ -774,6 +797,8 @@ class _DownloadedAlbumScreenState extends ConsumerState<DownloadedAlbumScreen> {
     BuildContext context,
     ColorScheme colorScheme,
     DownloadHistoryItem track,
+    List<DownloadHistoryItem> navigationItems,
+    int navigationIndex,
   ) {
     final isSelected = _selectedIds.contains(track.id);
 
@@ -791,7 +816,11 @@ class _DownloadedAlbumScreenState extends ConsumerState<DownloadedAlbumScreen> {
           ),
           onTap: _isSelectionMode
               ? () => _toggleSelection(track.id)
-              : () => _navigateToMetadataScreen(track),
+              : () => _navigateToMetadataScreen(
+                  track,
+                  navigationItems: navigationItems,
+                  navigationIndex: navigationIndex,
+                ),
           onLongPress: _isSelectionMode
               ? null
               : () => _enterSelectionMode(track.id),

lib/screens/home_tab.dart

@@ -1443,7 +1443,13 @@ class _HomeTabState extends ConsumerState<HomeTab>
                   button: true,
                   label: 'Open track ${item.trackName} by ${item.artistName}',
                   child: GestureDetector(
-                    onTap: () => _navigateToMetadataScreen(item),
+                    onTap: () => _navigateToMetadataScreen(
+                      item,
+                      navigationItems: items
+                          .take(itemCount)
+                          .toList(growable: false),
+                      navigationIndex: index,
+                    ),
                     child: Container(
                       width: coverSize,
                       margin: const EdgeInsets.only(right: 12),
@@ -1840,6 +1846,7 @@ class _HomeTabState extends ConsumerState<HomeTab>
       duration: item.durationMs ~/ 1000,
       trackNumber: null,
       discNumber: null,
+      totalDiscs: null,
       isrc: null,
       releaseDate: item.releaseDate,
       coverUrl: item.coverUrl,
@@ -2216,7 +2223,11 @@ class _HomeTabState extends ConsumerState<HomeTab>
     }
   }
 
-  Future<void> _navigateToMetadataScreen(DownloadHistoryItem item) async {
+  Future<void> _navigateToMetadataScreen(
+    DownloadHistoryItem item, {
+    List<DownloadHistoryItem>? navigationItems,
+    int? navigationIndex,
+  }) async {
     final navigator = Navigator.of(context);
     _precacheCover(item.coverUrl);
     final beforeModTime =
@@ -2225,7 +2236,13 @@ class _HomeTabState extends ConsumerState<HomeTab>
         );
     if (!mounted) return;
     final result = await navigator.push(
-      slidePageRoute<bool>(page: TrackMetadataScreen(item: item)),
+      slidePageRoute<bool>(
+        page: TrackMetadataScreen(
+          item: item,
+          historyNavigationItems: navigationItems,
+          navigationIndex: navigationIndex,
+        ),
+      ),
     );
     await DownloadedEmbeddedCoverResolver.scheduleRefreshForPath(
       item.filePath,
@@ -3014,6 +3031,8 @@ class _HomeTabState extends ConsumerState<HomeTab>
           albumId: albumItem.id,
           albumName: albumItem.name,
           coverUrl: albumItem.coverUrl,
+          initialAlbumType: albumItem.albumType,
+          initialTotalTracks: albumItem.totalTracks,
         ),
       ),
     );
@@ -4298,6 +4317,8 @@ class ExtensionAlbumScreen extends ConsumerStatefulWidget {
   final String albumId;
   final String albumName;
   final String? coverUrl;
+  final String? initialAlbumType;
+  final int? initialTotalTracks;
 
   const ExtensionAlbumScreen({
     super.key,
@@ -4305,6 +4326,8 @@ class ExtensionAlbumScreen extends ConsumerStatefulWidget {
     required this.albumId,
     required this.albumName,
     this.coverUrl,
+    this.initialAlbumType,
+    this.initialTotalTracks,
   });
 
   @override
@@ -4318,10 +4341,14 @@ class _ExtensionAlbumScreenState extends ConsumerState<ExtensionAlbumScreen> {
   String? _error;
   String? _artistId;
   String? _artistName;
+  String? _albumType;
+  int? _albumTotalTracks;
 
   @override
   void initState() {
     super.initState();
+    _albumType = normalizeOptionalString(widget.initialAlbumType);
+    _albumTotalTracks = widget.initialTotalTracks;
     _fetchTracks();
   }
 
@@ -4355,17 +4382,28 @@ class _ExtensionAlbumScreenState extends ConsumerState<ExtensionAlbumScreen> {
         return;
       }
 
-      final tracks = trackList
-          .map((t) => _parseTrack(t as Map<String, dynamic>))
-          .toList();
-
       final artistId = (result['artist_id'] ?? result['artistId'])?.toString();
       final artistName = result['artists'] as String?;
+      final albumType =
+          normalizeOptionalString(result['album_type']?.toString()) ??
+          _albumType;
+      final totalTracks = result['total_tracks'] as int? ?? _albumTotalTracks;
+      final tracks = trackList
+          .map(
+            (t) => _parseTrack(
+              t as Map<String, dynamic>,
+              albumTypeFallback: albumType,
+              totalTracksFallback: totalTracks,
+            ),
+          )
+          .toList();
 
       setState(() {
         _tracks = tracks;
         _artistId = artistId;
         _artistName = artistName;
+        _albumType = albumType;
+        _albumTotalTracks = totalTracks;
         _isLoading = false;
       });
     } catch (e) {
@@ -4377,7 +4415,11 @@ class _ExtensionAlbumScreenState extends ConsumerState<ExtensionAlbumScreen> {
     }
   }
 
-  Track _parseTrack(Map<String, dynamic> data) {
+  Track _parseTrack(
+    Map<String, dynamic> data, {
+    String? albumTypeFallback,
+    int? totalTracksFallback,
+  }) {
     int durationMs = 0;
     final durationValue = data['duration_ms'];
     if (durationValue is int) {
@@ -4403,7 +4445,17 @@ class _ExtensionAlbumScreenState extends ConsumerState<ExtensionAlbumScreen> {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
+      albumType:
+          normalizeOptionalString(data['album_type']?.toString()) ??
+          albumTypeFallback ??
+          _albumType,
+      totalTracks:
+          data['total_tracks'] as int? ??
+          totalTracksFallback ??
+          _albumTotalTracks,
+      composer: data['composer']?.toString(),
       source: widget.extensionId,
     );
   }
@@ -4562,7 +4614,10 @@ class _ExtensionPlaylistScreenState
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
+      totalTracks: data['total_tracks'] as int?,
+      composer: data['composer']?.toString(),
       source: widget.extensionId,
     );
   }
@@ -4739,7 +4794,10 @@ class _ExtensionArtistScreenState extends ConsumerState<ExtensionArtistScreen> {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
+      totalTracks: data['total_tracks'] as int?,
+      composer: data['composer']?.toString(),
       source: (data['provider_id'] ?? widget.extensionId).toString(),
     );
   }

lib/screens/local_album_screen.dart

@@ -1631,7 +1631,12 @@ class _LocalAlbumScreenState extends ConsumerState<LocalAlbumScreen> {
             try {
               await PlatformBridge.safDelete(item.filePath);
             } catch (_) {}
-            await localDb.deleteByPath(item.filePath);
+            await localDb.replaceWithConvertedItem(
+              item: item,
+              newFilePath: safUri,
+              targetFormat: targetFormat,
+              bitrate: bitrate,
+            );
           }
 
           try {
@@ -1643,8 +1648,12 @@ class _LocalAlbumScreenState extends ConsumerState<LocalAlbumScreen> {
             } catch (_) {}
           }
         } else {
-          // Regular file: just remove old entry, rescan will find the new one
-          await localDb.deleteByPath(item.filePath);
+          await localDb.replaceWithConvertedItem(
+            item: item,
+            newFilePath: newPath,
+            targetFormat: targetFormat,
+            bitrate: bitrate,
+          );
         }
 
         successCount++;

lib/screens/playlist_screen.dart

@@ -61,7 +61,6 @@ class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
     if (playlistId != null) {
       if (playlistId.startsWith('tidal:')) return 'tidal';
       if (playlistId.startsWith('qobuz:')) return 'qobuz';
-      if (playlistId.startsWith('deezer:')) return 'deezer';
     }
 
     final source = _tracks.firstOrNull?.source;
@@ -72,7 +71,6 @@ class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
     final trackId = _tracks.firstOrNull?.id ?? '';
     if (trackId.startsWith('tidal:')) return 'tidal';
     if (trackId.startsWith('qobuz:')) return 'qobuz';
-    if (trackId.startsWith('deezer:')) return 'deezer';
     return null;
   }
 
@@ -164,7 +162,10 @@ class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
+      totalTracks: data['total_tracks'] as int?,
+      composer: data['composer']?.toString(),
     );
   }
 

lib/screens/queue_tab.dart

@@ -2963,15 +2963,23 @@ class _QueueTabState extends ConsumerState<QueueTab> {
   }
 
   Future<void> _navigateToHistoryMetadataScreen(
-    DownloadHistoryItem item,
-  ) async {
+    DownloadHistoryItem item, {
+    List<DownloadHistoryItem>? navigationItems,
+    int? navigationIndex,
+  }) async {
     final navigator = Navigator.of(context);
     _precacheCover(item.coverUrl);
     _searchFocusNode.unfocus();
     final beforeModTime = await _readFileModTimeMillis(item.filePath);
     if (!mounted) return;
     final result = await navigator.push(
-      slidePageRoute<bool>(page: TrackMetadataScreen(item: item)),
+      slidePageRoute<bool>(
+        page: TrackMetadataScreen(
+          item: item,
+          historyNavigationItems: navigationItems,
+          navigationIndex: navigationIndex,
+        ),
+      ),
     );
     _searchFocusNode.unfocus();
     if (result == true) {
@@ -2988,11 +2996,21 @@ class _QueueTabState extends ConsumerState<QueueTab> {
     );
   }
 
-  void _navigateToLocalMetadataScreen(LocalLibraryItem item) {
+  void _navigateToLocalMetadataScreen(
+    LocalLibraryItem item, {
+    List<LocalLibraryItem>? navigationItems,
+    int? navigationIndex,
+  }) {
     _searchFocusNode.unfocus();
     Navigator.push(
       context,
-      slidePageRoute<void>(page: TrackMetadataScreen(localItem: item)),
+      slidePageRoute<void>(
+        page: TrackMetadataScreen(
+          localItem: item,
+          localNavigationItems: navigationItems,
+          navigationIndex: navigationIndex,
+        ),
+      ),
     ).then((_) => _searchFocusNode.unfocus());
   }
 
@@ -4227,6 +4245,25 @@ class _QueueTabState extends ConsumerState<QueueTab> {
     final filteredUnifiedItems = filterData.filteredUnifiedItems;
     final totalTrackCount = filterData.totalTrackCount;
     final totalAlbumCount = filterData.totalAlbumCount;
+    final downloadedNavigationItems = <DownloadHistoryItem>[];
+    final downloadedNavigationIndexByUnifiedId = <String, int>{};
+    final localNavigationItems = <LocalLibraryItem>[];
+    final localNavigationIndexByUnifiedId = <String, int>{};
+
+    for (final item in filteredUnifiedItems) {
+      final historyItem = item.historyItem;
+      if (historyItem != null) {
+        downloadedNavigationIndexByUnifiedId[item.id] =
+            downloadedNavigationItems.length;
+        downloadedNavigationItems.add(historyItem);
+      }
+
+      final localItem = item.localItem;
+      if (localItem != null) {
+        localNavigationIndexByUnifiedId[item.id] = localNavigationItems.length;
+        localNavigationItems.add(localItem);
+      }
+    }
 
     return CustomScrollView(
       slivers: [
@@ -4419,12 +4456,26 @@ class _QueueTabState extends ConsumerState<QueueTab> {
                               context,
                               item,
                               colorScheme,
+                              downloadedNavigationItems:
+                                  downloadedNavigationItems,
+                              downloadedNavigationIndex:
+                                  downloadedNavigationIndexByUnifiedId[item.id],
+                              localNavigationItems: localNavigationItems,
+                              localNavigationIndex:
+                                  localNavigationIndexByUnifiedId[item.id],
                             ),
                           ),
                           child: _buildUnifiedGridItem(
                             context,
                             item,
                             colorScheme,
+                            downloadedNavigationItems:
+                                downloadedNavigationItems,
+                            downloadedNavigationIndex:
+                                downloadedNavigationIndexByUnifiedId[item.id],
+                            localNavigationItems: localNavigationItems,
+                            localNavigationIndex:
+                                localNavigationIndexByUnifiedId[item.id],
                           ),
                         ),
                       );
@@ -4472,12 +4523,25 @@ class _QueueTabState extends ConsumerState<QueueTab> {
                             context,
                             item,
                             colorScheme,
+                            downloadedNavigationItems:
+                                downloadedNavigationItems,
+                            downloadedNavigationIndex:
+                                downloadedNavigationIndexByUnifiedId[item.id],
+                            localNavigationItems: localNavigationItems,
+                            localNavigationIndex:
+                                localNavigationIndexByUnifiedId[item.id],
                           ),
                         ),
                         child: _buildUnifiedLibraryItem(
                           context,
                           item,
                           colorScheme,
+                          downloadedNavigationItems: downloadedNavigationItems,
+                          downloadedNavigationIndex:
+                              downloadedNavigationIndexByUnifiedId[item.id],
+                          localNavigationItems: localNavigationItems,
+                          localNavigationIndex:
+                              localNavigationIndexByUnifiedId[item.id],
                         ),
                       ),
                     );
@@ -4540,6 +4604,12 @@ class _QueueTabState extends ConsumerState<QueueTab> {
                           context,
                           item,
                           colorScheme,
+                          downloadedNavigationItems: downloadedNavigationItems,
+                          downloadedNavigationIndex:
+                              downloadedNavigationIndexByUnifiedId[item.id],
+                          localNavigationItems: localNavigationItems,
+                          localNavigationIndex:
+                              localNavigationIndexByUnifiedId[item.id],
                         ),
                       );
                     }, childCount: filteredUnifiedItems.length),
@@ -4554,6 +4624,12 @@ class _QueueTabState extends ConsumerState<QueueTab> {
                         context,
                         item,
                         colorScheme,
+                        downloadedNavigationItems: downloadedNavigationItems,
+                        downloadedNavigationIndex:
+                            downloadedNavigationIndexByUnifiedId[item.id],
+                        localNavigationItems: localNavigationItems,
+                        localNavigationIndex:
+                            localNavigationIndexByUnifiedId[item.id],
                       ),
                     );
                   }, childCount: filteredUnifiedItems.length),
@@ -5853,13 +5929,27 @@ class _QueueTabState extends ConsumerState<QueueTab> {
             final baseName = dotIdx > 0
                 ? oldFileName.substring(0, dotIdx)
                 : oldFileName;
-            final newExt = targetFormat.toLowerCase() == 'opus'
-                ? '.opus'
-                : '.mp3';
+            String newExt;
+            String mimeType;
+            switch (targetFormat.toLowerCase()) {
+              case 'opus':
+                newExt = '.opus';
+                mimeType = 'audio/opus';
+                break;
+              case 'alac':
+                newExt = '.m4a';
+                mimeType = 'audio/mp4';
+                break;
+              case 'flac':
+                newExt = '.flac';
+                mimeType = 'audio/flac';
+                break;
+              default:
+                newExt = '.mp3';
+                mimeType = 'audio/mpeg';
+                break;
+            }
             final newFileName = '$baseName$newExt';
-            final mimeType = targetFormat.toLowerCase() == 'opus'
-                ? 'audio/opus'
-                : 'audio/mpeg';
 
             final safUri = await PlatformBridge.createSafFileFromPath(
               treeUri: treeUri,
@@ -5884,7 +5974,12 @@ class _QueueTabState extends ConsumerState<QueueTab> {
             try {
               await PlatformBridge.safDelete(item.filePath);
             } catch (_) {}
-            await LibraryDatabase.instance.deleteByPath(item.filePath);
+            await LibraryDatabase.instance.replaceWithConvertedItem(
+              item: item.localItem!,
+              newFilePath: safUri,
+              targetFormat: targetFormat,
+              bitrate: bitrate,
+            );
           }
 
           try {
@@ -5903,7 +5998,12 @@ class _QueueTabState extends ConsumerState<QueueTab> {
             clearAudioSpecs: true,
           );
         } else if (item.localItem != null) {
-          await LibraryDatabase.instance.deleteByPath(item.filePath);
+          await LibraryDatabase.instance.replaceWithConvertedItem(
+            item: item.localItem!,
+            newFilePath: newPath,
+            targetFormat: targetFormat,
+            bitrate: bitrate,
+          );
         }
 
         successCount++;
@@ -6585,8 +6685,12 @@ class _QueueTabState extends ConsumerState<QueueTab> {
   Widget _buildUnifiedLibraryItem(
     BuildContext context,
     UnifiedLibraryItem item,
-    ColorScheme colorScheme,
-  ) {
+    ColorScheme colorScheme, {
+    required List<DownloadHistoryItem> downloadedNavigationItems,
+    required int? downloadedNavigationIndex,
+    required List<LocalLibraryItem> localNavigationItems,
+    required int? localNavigationIndex,
+  }) {
     final fileExistsListenable = _fileExistsListenable(item.filePath);
     final isSelected = _selectedIds.contains(item.id);
     final date = item.addedAt;
@@ -6616,9 +6720,17 @@ class _QueueTabState extends ConsumerState<QueueTab> {
           onTap: _isSelectionMode
               ? () => _toggleSelection(item.id)
               : isDownloaded
-              ? () => _navigateToHistoryMetadataScreen(item.historyItem!)
+              ? () => _navigateToHistoryMetadataScreen(
+                  item.historyItem!,
+                  navigationItems: downloadedNavigationItems,
+                  navigationIndex: downloadedNavigationIndex,
+                )
               : item.localItem != null
-              ? () => _navigateToLocalMetadataScreen(item.localItem!)
+              ? () => _navigateToLocalMetadataScreen(
+                  item.localItem!,
+                  navigationItems: localNavigationItems,
+                  navigationIndex: localNavigationIndex,
+                )
               : () => _openFile(
                   item.filePath,
                   title: item.trackName,
@@ -6792,8 +6904,12 @@ class _QueueTabState extends ConsumerState<QueueTab> {
   Widget _buildUnifiedGridItem(
     BuildContext context,
     UnifiedLibraryItem item,
-    ColorScheme colorScheme,
-  ) {
+    ColorScheme colorScheme, {
+    required List<DownloadHistoryItem> downloadedNavigationItems,
+    required int? downloadedNavigationIndex,
+    required List<LocalLibraryItem> localNavigationItems,
+    required int? localNavigationIndex,
+  }) {
     final fileExistsListenable = _fileExistsListenable(item.filePath);
     final isSelected = _selectedIds.contains(item.id);
     final isDownloaded = item.source == LibraryItemSource.downloaded;
@@ -6802,9 +6918,17 @@ class _QueueTabState extends ConsumerState<QueueTab> {
       onTap: _isSelectionMode
           ? () => _toggleSelection(item.id)
           : isDownloaded
-          ? () => _navigateToHistoryMetadataScreen(item.historyItem!)
+          ? () => _navigateToHistoryMetadataScreen(
+              item.historyItem!,
+              navigationItems: downloadedNavigationItems,
+              navigationIndex: downloadedNavigationIndex,
+            )
           : item.localItem != null
-          ? () => _navigateToLocalMetadataScreen(item.localItem!)
+          ? () => _navigateToLocalMetadataScreen(
+              item.localItem!,
+              navigationItems: localNavigationItems,
+              navigationIndex: localNavigationIndex,
+            )
           : () => _openFile(
               item.filePath,
               title: item.trackName,

lib/screens/settings/download_fallback_extensions_page.dart

@@ -0,0 +1,250 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:spotiflac_android/l10n/l10n.dart';
+import 'package:spotiflac_android/providers/extension_provider.dart';
+import 'package:spotiflac_android/providers/settings_provider.dart';
+import 'package:spotiflac_android/utils/app_bar_layout.dart';
+import 'package:spotiflac_android/widgets/settings_group.dart';
+
+class DownloadFallbackExtensionsPage extends ConsumerStatefulWidget {
+  const DownloadFallbackExtensionsPage({super.key});
+
+  @override
+  ConsumerState<DownloadFallbackExtensionsPage> createState() =>
+      _DownloadFallbackExtensionsPageState();
+}
+
+class _DownloadFallbackExtensionsPageState
+    extends ConsumerState<DownloadFallbackExtensionsPage> {
+  late List<Extension> _extensions;
+  late Set<String> _selectedExtensionIds;
+  bool _hasChanges = false;
+
+  @override
+  void initState() {
+    super.initState();
+    _loadExtensions();
+  }
+
+  void _loadExtensions() {
+    final extState = ref.read(extensionProvider);
+    final settings = ref.read(settingsProvider);
+
+    _extensions = extState.extensions
+        .where(
+          (extension) => extension.enabled && extension.hasDownloadProvider,
+        )
+        .toList();
+
+    final savedIds = settings.downloadFallbackExtensionIds;
+    if (savedIds == null) {
+      _selectedExtensionIds = _extensions
+          .map((extension) => extension.id)
+          .toSet();
+    } else {
+      final allowedIds = _extensions.map((extension) => extension.id).toSet();
+      _selectedExtensionIds = savedIds
+          .where((extensionId) => allowedIds.contains(extensionId))
+          .toSet();
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final colorScheme = Theme.of(context).colorScheme;
+    final topPadding = normalizedHeaderTopPadding(context);
+
+    return PopScope(
+      canPop: !_hasChanges,
+      onPopInvokedWithResult: (didPop, result) async {
+        if (didPop) return;
+        final shouldPop = await _confirmDiscard(context);
+        if (shouldPop && context.mounted) {
+          Navigator.pop(context);
+        }
+      },
+      child: Scaffold(
+        body: CustomScrollView(
+          slivers: [
+            SliverAppBar(
+              expandedHeight: 120 + topPadding,
+              collapsedHeight: kToolbarHeight,
+              floating: false,
+              pinned: true,
+              backgroundColor: colorScheme.surface,
+              surfaceTintColor: Colors.transparent,
+              leading: IconButton(
+                tooltip: MaterialLocalizations.of(context).backButtonTooltip,
+                icon: const Icon(Icons.arrow_back),
+                onPressed: () async {
+                  if (_hasChanges) {
+                    final shouldPop = await _confirmDiscard(context);
+                    if (shouldPop && context.mounted) {
+                      Navigator.pop(context);
+                    }
+                  } else {
+                    Navigator.pop(context);
+                  }
+                },
+              ),
+              actions: [
+                if (_hasChanges)
+                  TextButton(
+                    onPressed: _saveChanges,
+                    child: Text(context.l10n.dialogSave),
+                  ),
+              ],
+              flexibleSpace: LayoutBuilder(
+                builder: (context, constraints) {
+                  final maxHeight = 120 + topPadding;
+                  final minHeight = kToolbarHeight + topPadding;
+                  final expandRatio =
+                      ((constraints.maxHeight - minHeight) /
+                              (maxHeight - minHeight))
+                          .clamp(0.0, 1.0);
+                  final leftPadding = 56 - (32 * expandRatio);
+                  return FlexibleSpaceBar(
+                    expandedTitleScale: 1.0,
+                    titlePadding: EdgeInsets.only(
+                      left: leftPadding,
+                      bottom: 16,
+                    ),
+                    title: Text(
+                      context.l10n.extensionsFallbackTitle,
+                      style: TextStyle(
+                        fontSize: 20 + (8 * expandRatio),
+                        fontWeight: FontWeight.bold,
+                        color: colorScheme.onSurface,
+                      ),
+                    ),
+                  );
+                },
+              ),
+            ),
+            SliverToBoxAdapter(
+              child: Padding(
+                padding: const EdgeInsets.all(16),
+                child: Text(
+                  context.l10n.providerPriorityFallbackExtensionsDescription,
+                  style: Theme.of(context).textTheme.bodyMedium?.copyWith(
+                    color: colorScheme.onSurfaceVariant,
+                  ),
+                ),
+              ),
+            ),
+            if (_extensions.isEmpty)
+              SliverToBoxAdapter(
+                child: Padding(
+                  padding: const EdgeInsets.symmetric(horizontal: 16),
+                  child: Container(
+                    padding: const EdgeInsets.all(20),
+                    decoration: BoxDecoration(
+                      color: colorScheme.surfaceContainerHighest.withValues(
+                        alpha: 0.4,
+                      ),
+                      borderRadius: BorderRadius.circular(16),
+                    ),
+                    child: Text(
+                      context.l10n.extensionsNoDownloadProvider,
+                      style: Theme.of(context).textTheme.bodyMedium?.copyWith(
+                        color: colorScheme.onSurfaceVariant,
+                      ),
+                    ),
+                  ),
+                ),
+              ),
+            if (_extensions.isNotEmpty)
+              SliverPadding(
+                padding: const EdgeInsets.symmetric(horizontal: 16),
+                sliver: SliverToBoxAdapter(
+                  child: SettingsGroup(
+                    margin: EdgeInsets.zero,
+                    children: List.generate(_extensions.length, (index) {
+                      final extension = _extensions[index];
+                      final isSelected = _selectedExtensionIds.contains(
+                        extension.id,
+                      );
+                      return SettingsSwitchItem(
+                        icon: Icons.extension_rounded,
+                        title: extension.displayName,
+                        subtitle: extension.id,
+                        value: isSelected,
+                        showDivider: index != _extensions.length - 1,
+                        onChanged: (value) {
+                          setState(() {
+                            if (value) {
+                              _selectedExtensionIds.add(extension.id);
+                            } else {
+                              _selectedExtensionIds.remove(extension.id);
+                            }
+                            _hasChanges = true;
+                          });
+                        },
+                      );
+                    }),
+                  ),
+                ),
+              ),
+            if (_extensions.isNotEmpty)
+              SliverToBoxAdapter(
+                child: Padding(
+                  padding: const EdgeInsets.fromLTRB(16, 8, 16, 0),
+                  child: Text(
+                    context.l10n.providerPriorityFallbackExtensionsHint,
+                    style: Theme.of(context).textTheme.bodySmall?.copyWith(
+                      color: colorScheme.onSurfaceVariant,
+                    ),
+                  ),
+                ),
+              ),
+            const SliverToBoxAdapter(child: SizedBox(height: 32)),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Future<bool> _confirmDiscard(BuildContext context) async {
+    final result = await showDialog<bool>(
+      context: context,
+      builder: (context) => AlertDialog(
+        title: Text(context.l10n.dialogDiscardChanges),
+        content: Text(context.l10n.dialogUnsavedChanges),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.pop(context, false),
+            child: Text(context.l10n.dialogCancel),
+          ),
+          FilledButton(
+            onPressed: () => Navigator.pop(context, true),
+            child: Text(context.l10n.dialogDiscard),
+          ),
+        ],
+      ),
+    );
+    return result ?? false;
+  }
+
+  void _saveChanges() {
+    final allExtensionIds = _extensions
+        .map((extension) => extension.id)
+        .toList();
+    final selectedExtensionIds = allExtensionIds
+        .where(_selectedExtensionIds.contains)
+        .toList();
+    final fallbackExtensionIds =
+        selectedExtensionIds.length == allExtensionIds.length
+        ? null
+        : selectedExtensionIds;
+
+    ref
+        .read(settingsProvider.notifier)
+        .setDownloadFallbackExtensionIds(fallbackExtensionIds);
+    setState(() {
+      _hasChanges = false;
+    });
+    ScaffoldMessenger.of(context).showSnackBar(
+      SnackBar(content: Text(context.l10n.snackbarProviderPrioritySaved)),
+    );
+  }
+}

lib/screens/settings/download_settings_page.dart

@@ -24,7 +24,7 @@ class DownloadSettingsPage extends ConsumerStatefulWidget {
 }
 
 class _DownloadSettingsPageState extends ConsumerState<DownloadSettingsPage> {
-  static const _builtInServices = ['tidal', 'qobuz', 'deezer'];
+  static const _builtInServices = ['tidal', 'qobuz'];
   static const _songLinkRegions = [
     'AD',
     'AE',
@@ -2053,7 +2053,7 @@ class _ServiceSelector extends ConsumerWidget {
   @override
   Widget build(BuildContext context, WidgetRef ref) {
     final extState = ref.watch(extensionProvider);
-    final builtInServiceIds = ['tidal', 'qobuz', 'deezer'];
+    final builtInServiceIds = ['tidal', 'qobuz'];
 
     final extensionProviders = extState.extensions
         .where((e) => e.enabled && e.hasDownloadProvider)

lib/screens/settings/extensions_page.dart

@@ -8,9 +8,10 @@ import 'package:spotiflac_android/models/settings.dart';
 import 'package:spotiflac_android/providers/extension_provider.dart';
 import 'package:spotiflac_android/providers/explore_provider.dart';
 import 'package:spotiflac_android/providers/settings_provider.dart';
+import 'package:spotiflac_android/screens/settings/download_fallback_extensions_page.dart';
 import 'package:spotiflac_android/screens/settings/extension_detail_page.dart';
-import 'package:spotiflac_android/screens/settings/provider_priority_page.dart';
 import 'package:spotiflac_android/screens/settings/metadata_provider_priority_page.dart';
+import 'package:spotiflac_android/screens/settings/provider_priority_page.dart';
 import 'package:spotiflac_android/utils/app_bar_layout.dart';
 import 'package:spotiflac_android/widgets/settings_group.dart';
 
@@ -151,6 +152,7 @@ class _ExtensionsPageState extends ConsumerState<ExtensionsPage> {
               child: SettingsGroup(
                 children: [
                   _DownloadPriorityItem(),
+                  _DownloadFallbackItem(),
                   _MetadataPriorityItem(),
                   _SearchProviderSelector(),
                   _HomeFeedProviderSelector(),
@@ -588,6 +590,73 @@ class _MetadataPriorityItem extends ConsumerWidget {
   }
 }
 
+class _DownloadFallbackItem extends ConsumerWidget {
+  const _DownloadFallbackItem();
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final extState = ref.watch(extensionProvider);
+    final colorScheme = Theme.of(context).colorScheme;
+
+    final hasDownloadExtensions = extState.extensions.any(
+      (e) => e.enabled && e.hasDownloadProvider,
+    );
+
+    return InkWell(
+      onTap: hasDownloadExtensions
+          ? () => Navigator.push(
+              context,
+              MaterialPageRoute<void>(
+                builder: (_) => const DownloadFallbackExtensionsPage(),
+              ),
+            )
+          : null,
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
+        child: Row(
+          children: [
+            Icon(
+              Icons.alt_route,
+              color: hasDownloadExtensions
+                  ? colorScheme.onSurfaceVariant
+                  : colorScheme.outline,
+            ),
+            const SizedBox(width: 16),
+            Expanded(
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Text(
+                    context.l10n.extensionsFallbackTitle,
+                    style: Theme.of(context).textTheme.bodyLarge?.copyWith(
+                      color: hasDownloadExtensions ? null : colorScheme.outline,
+                    ),
+                  ),
+                  const SizedBox(height: 2),
+                  Text(
+                    hasDownloadExtensions
+                        ? context.l10n.extensionsFallbackSubtitle
+                        : context.l10n.extensionsNoDownloadProvider,
+                    style: Theme.of(context).textTheme.bodySmall?.copyWith(
+                      color: colorScheme.onSurfaceVariant,
+                    ),
+                  ),
+                ],
+              ),
+            ),
+            Icon(
+              Icons.chevron_right,
+              color: hasDownloadExtensions
+                  ? colorScheme.onSurfaceVariant
+                  : colorScheme.outline,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
 class _SearchProviderSelector extends ConsumerWidget {
   const _SearchProviderSelector();
 

lib/screens/track_metadata_screen.dart

@@ -24,6 +24,7 @@ import 'package:spotiflac_android/utils/lyrics_metadata_helper.dart';
 import 'package:spotiflac_android/utils/mime_utils.dart';
 import 'package:spotiflac_android/utils/image_cache_utils.dart';
 import 'package:spotiflac_android/utils/string_utils.dart';
+import 'package:spotiflac_android/widgets/animation_utils.dart';
 import 'package:spotiflac_android/widgets/audio_analysis_widget.dart';
 
 final _log = AppLogger('TrackMetadata');
@@ -41,12 +42,35 @@ class _EmbeddedCoverPreviewCacheEntry {
 class TrackMetadataScreen extends ConsumerStatefulWidget {
   final DownloadHistoryItem? item;
   final LocalLibraryItem? localItem;
+  final List<DownloadHistoryItem>? historyNavigationItems;
+  final List<LocalLibraryItem>? localNavigationItems;
+  final int? navigationIndex;
 
-  const TrackMetadataScreen({super.key, this.item, this.localItem})
-    : assert(
-        item != null || localItem != null,
-        'Either item or localItem must be provided',
-      );
+  const TrackMetadataScreen({
+    super.key,
+    this.item,
+    this.localItem,
+    this.historyNavigationItems,
+    this.localNavigationItems,
+    this.navigationIndex,
+  }) : assert(
+         item != null || localItem != null,
+         'Either item or localItem must be provided',
+       ),
+       assert(
+         historyNavigationItems == null || localNavigationItems == null,
+         'Provide only one navigation list type',
+       ),
+       assert(
+         navigationIndex == null ||
+             ((historyNavigationItems != null &&
+                     navigationIndex >= 0 &&
+                     navigationIndex < historyNavigationItems.length) ||
+                 (localNavigationItems != null &&
+                     navigationIndex >= 0 &&
+                     navigationIndex < localNavigationItems.length)),
+         'navigationIndex must be within the provided navigation list',
+       );
 
   @override
   ConsumerState<TrackMetadataScreen> createState() =>
@@ -74,6 +98,7 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
   bool _isConverting = false;
   bool _hasMetadataChanges = false;
   bool _hasLoadedResolvedAudioMetadata = false;
+  bool _isTrackSwipeNavigationInFlight = false;
   Map<String, dynamic>? _editedMetadata;
   String? _embeddedCoverPreviewPath;
   final ScrollController _scrollController = ScrollController();
@@ -252,7 +277,7 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
     }
     if (mounted &&
         exists &&
-        !_isLocalItem &&
+        !_isCueVirtualTrack &&
         !_hasLoadedResolvedAudioMetadata) {
       unawaited(_refreshResolvedAudioMetadataFromFile());
     }
@@ -291,8 +316,9 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
   }
 
   Future<void> _refreshResolvedAudioMetadataFromFile() async {
-    if (_isLocalItem ||
-        _downloadItem == null ||
+    if ((_isLocalItem && _localLibraryItem == null) ||
+        (!_isLocalItem && _downloadItem == null) ||
+        _isCueVirtualTrack ||
         _hasLoadedResolvedAudioMetadata) {
       return;
     }
@@ -326,8 +352,33 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
 
       // Resolve label/copyright from file when the model doesn't carry them
       // (e.g. local library items, or download history items without these fields).
+      final resolvedTrackNumber = _readPositiveInt(metadata['track_number']);
+      final resolvedTotalTracks = _readPositiveInt(metadata['total_tracks']);
+      final resolvedDiscNumber = _readPositiveInt(metadata['disc_number']);
+      final resolvedTotalDiscs = _readPositiveInt(metadata['total_discs']);
+      final resolvedComposer = metadata['composer']?.toString();
       final resolvedLabel = metadata['label']?.toString();
       final resolvedCopyright = metadata['copyright']?.toString();
+      final needsTrackNumber =
+          resolvedTrackNumber != null &&
+          resolvedTrackNumber > 0 &&
+          trackNumber == null;
+      final needsTotalTracks =
+          resolvedTotalTracks != null &&
+          resolvedTotalTracks > 0 &&
+          totalTracks == null;
+      final needsDiscNumber =
+          resolvedDiscNumber != null &&
+          resolvedDiscNumber > 0 &&
+          discNumber == null;
+      final needsTotalDiscs =
+          resolvedTotalDiscs != null &&
+          resolvedTotalDiscs > 0 &&
+          totalDiscs == null;
+      final needsComposer =
+          resolvedComposer != null &&
+          resolvedComposer.isNotEmpty &&
+          (composer == null || composer!.isEmpty);
       final needsLabel =
           resolvedLabel != null &&
           resolvedLabel.isNotEmpty &&
@@ -338,14 +389,25 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
           (copyright == null || copyright!.isEmpty);
 
       final shouldPersistResolvedAudioMetadata =
-          resolvedBitDepth != null ||
-          resolvedSampleRate != null ||
-          (isPlaceholderQualityLabel(_quality) && resolvedQuality != null);
+          !_isLocalItem &&
+          (resolvedBitDepth != null ||
+              resolvedSampleRate != null ||
+              needsTrackNumber ||
+              needsTotalTracks ||
+              needsDiscNumber ||
+              needsTotalDiscs ||
+              needsComposer ||
+              (isPlaceholderQualityLabel(_quality) && resolvedQuality != null));
 
       if ((resolvedBitDepth != null ||
               resolvedSampleRate != null ||
               needsAlbum ||
               needsDuration ||
+              needsTrackNumber ||
+              needsTotalTracks ||
+              needsDiscNumber ||
+              needsTotalDiscs ||
+              needsComposer ||
               needsLabel ||
               needsCopyright ||
               isPlaceholderQualityLabel(_quality)) &&
@@ -359,6 +421,11 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
             if (resolvedSampleRate != null) 'sample_rate': resolvedSampleRate,
             if (needsAlbum) 'album': resolvedAlbum,
             if (needsDuration) 'duration': resolvedDuration,
+            if (needsTrackNumber) 'track_number': resolvedTrackNumber,
+            if (needsTotalTracks) 'total_tracks': resolvedTotalTracks,
+            if (needsDiscNumber) 'disc_number': resolvedDiscNumber,
+            if (needsTotalDiscs) 'total_discs': resolvedTotalDiscs,
+            if (needsComposer) 'composer': resolvedComposer,
             if (needsLabel) 'label': resolvedLabel,
             if (needsCopyright) 'copyright': resolvedCopyright,
           };
@@ -373,6 +440,11 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
               quality: resolvedQuality,
               bitDepth: resolvedBitDepth,
               sampleRate: resolvedSampleRate,
+              trackNumber: needsTrackNumber ? resolvedTrackNumber : null,
+              totalTracks: needsTotalTracks ? resolvedTotalTracks : null,
+              discNumber: needsDiscNumber ? resolvedDiscNumber : null,
+              totalDiscs: needsTotalDiscs ? resolvedTotalDiscs : null,
+              composer: needsComposer ? resolvedComposer : null,
             );
       }
     } catch (e) {
@@ -445,6 +517,17 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
   bool get _isLocalItem => widget.localItem != null;
   DownloadHistoryItem? get _downloadItem => widget.item;
   LocalLibraryItem? get _localLibraryItem => widget.localItem;
+  bool get _hasHistoryNavigation =>
+      widget.historyNavigationItems != null && widget.navigationIndex != null;
+  bool get _hasLocalNavigation =>
+      widget.localNavigationItems != null && widget.navigationIndex != null;
+  bool get _hasTrackSwipeNavigation =>
+      _hasHistoryNavigation || _hasLocalNavigation;
+  int? get _navigationIndex => widget.navigationIndex;
+  int get _navigationLength =>
+      widget.historyNavigationItems?.length ??
+      widget.localNavigationItems?.length ??
+      0;
 
   String get _itemId =>
       _isLocalItem ? _localLibraryItem!.id : _downloadItem!.id;
@@ -480,6 +563,12 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
         : _downloadItem!.trackNumber;
   }
 
+  int? get totalTracks =>
+      _readPositiveInt(_editedMetadata?['total_tracks']) ??
+      (_isLocalItem
+          ? _localLibraryItem!.totalTracks
+          : _downloadItem!.totalTracks);
+
   int? get discNumber {
     final edited = _editedMetadata?['disc_number'];
     if (edited != null) {
@@ -491,6 +580,12 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
         : _downloadItem!.discNumber;
   }
 
+  int? get totalDiscs =>
+      _readPositiveInt(_editedMetadata?['total_discs']) ??
+      (_isLocalItem
+          ? _localLibraryItem!.totalDiscs
+          : _downloadItem!.totalDiscs);
+
   String? get releaseDate =>
       _editedMetadata?['date']?.toString() ??
       (_isLocalItem
@@ -517,10 +612,13 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
       (_isLocalItem ? _localLibraryItem!.genre : _downloadItem!.genre);
   String? get label =>
       _editedMetadata?['label']?.toString() ??
-      (_isLocalItem ? null : _downloadItem!.label);
+      (_isLocalItem ? _localLibraryItem!.label : _downloadItem!.label);
   String? get copyright =>
       _editedMetadata?['copyright']?.toString() ??
-      (_isLocalItem ? null : _downloadItem!.copyright);
+      (_isLocalItem ? _localLibraryItem!.copyright : _downloadItem!.copyright);
+  String? get composer =>
+      _editedMetadata?['composer']?.toString() ??
+      (_isLocalItem ? _localLibraryItem!.composer : null);
   int? get duration =>
       _readPositiveInt(_editedMetadata?['duration']) ??
       (_isLocalItem ? _localLibraryItem!.duration : _downloadItem!.duration);
@@ -743,118 +841,165 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
     Navigator.pop(context, _hasMetadataChanges ? true : null);
   }
 
+  void _handleHorizontalDragEnd(DragEndDetails details) {
+    final velocity = details.primaryVelocity;
+    if (velocity == null || velocity.abs() < 350) return;
+    if (velocity < 0) {
+      unawaited(_navigateToAdjacentTrack(1));
+    } else {
+      unawaited(_navigateToAdjacentTrack(-1));
+    }
+  }
+
+  Future<void> _navigateToAdjacentTrack(int offset) async {
+    if (_isTrackSwipeNavigationInFlight || !_hasTrackSwipeNavigation) return;
+    final currentIndex = _navigationIndex;
+    if (currentIndex == null) return;
+    final targetIndex = currentIndex + offset;
+    if (targetIndex < 0 || targetIndex >= _navigationLength) return;
+
+    _isTrackSwipeNavigationInFlight = true;
+    final result = await Navigator.of(context).push<bool>(
+      adjacentHorizontalPageRoute<bool>(
+        page: _buildSiblingTrackScreen(targetIndex),
+        fromRight: offset > 0,
+      ),
+    );
+    if (!mounted) return;
+    Navigator.pop(context, result == true || _hasMetadataChanges ? true : null);
+  }
+
+  TrackMetadataScreen _buildSiblingTrackScreen(int targetIndex) {
+    if (_hasHistoryNavigation) {
+      return TrackMetadataScreen(
+        item: widget.historyNavigationItems![targetIndex],
+        historyNavigationItems: widget.historyNavigationItems,
+        navigationIndex: targetIndex,
+      );
+    }
+    return TrackMetadataScreen(
+      localItem: widget.localNavigationItems![targetIndex],
+      localNavigationItems: widget.localNavigationItems,
+      navigationIndex: targetIndex,
+    );
+  }
+
   @override
   Widget build(BuildContext context) {
     final colorScheme = Theme.of(context).colorScheme;
     final expandedHeight = _calculateExpandedHeight(context);
 
-    return Scaffold(
-      body: CustomScrollView(
-        controller: _scrollController,
-        slivers: [
-          SliverAppBar(
-            expandedHeight: expandedHeight,
-            pinned: true,
-            stretch: true,
-            backgroundColor: colorScheme.surface,
-            surfaceTintColor: Colors.transparent,
-            title: AnimatedOpacity(
-              duration: const Duration(milliseconds: 200),
-              opacity: _showTitleInAppBar ? 1.0 : 0.0,
-              child: Text(
-                trackName,
-                style: TextStyle(
-                  color: colorScheme.onSurface,
-                  fontWeight: FontWeight.w600,
-                  fontSize: 16,
-                ),
-                maxLines: 1,
-                overflow: TextOverflow.ellipsis,
-              ),
-            ),
-            flexibleSpace: LayoutBuilder(
-              builder: (context, constraints) {
-                final collapseRatio =
-                    (constraints.maxHeight - kToolbarHeight) /
-                    (expandedHeight - kToolbarHeight);
-                final showContent = collapseRatio > 0.3;
-
-                return FlexibleSpaceBar(
-                  collapseMode: CollapseMode.pin,
-                  background: _buildHeaderBackground(
-                    context,
-                    colorScheme,
-                    expandedHeight,
-                    showContent,
+    return GestureDetector(
+      behavior: HitTestBehavior.translucent,
+      onHorizontalDragEnd: _handleHorizontalDragEnd,
+      child: Scaffold(
+        body: CustomScrollView(
+          controller: _scrollController,
+          slivers: [
+            SliverAppBar(
+              expandedHeight: expandedHeight,
+              pinned: true,
+              stretch: true,
+              backgroundColor: colorScheme.surface,
+              surfaceTintColor: Colors.transparent,
+              title: AnimatedOpacity(
+                duration: const Duration(milliseconds: 200),
+                opacity: _showTitleInAppBar ? 1.0 : 0.0,
+                child: Text(
+                  trackName,
+                  style: TextStyle(
+                    color: colorScheme.onSurface,
+                    fontWeight: FontWeight.w600,
+                    fontSize: 16,
                   ),
-                  stretchModes: const [StretchMode.zoomBackground],
-                );
-              },
-            ),
-            leading: IconButton(
-              tooltip: MaterialLocalizations.of(context).backButtonTooltip,
-              icon: Container(
-                padding: const EdgeInsets.all(8),
-                decoration: BoxDecoration(
-                  color: Colors.black.withValues(alpha: 0.4),
-                  shape: BoxShape.circle,
+                  maxLines: 1,
+                  overflow: TextOverflow.ellipsis,
                 ),
-                child: const Icon(Icons.arrow_back, color: Colors.white),
               ),
-              onPressed: _popWithMetadataResult,
-            ),
-            actions: [
-              IconButton(
-                tooltip: MaterialLocalizations.of(context).showMenuTooltip,
+              flexibleSpace: LayoutBuilder(
+                builder: (context, constraints) {
+                  final collapseRatio =
+                      (constraints.maxHeight - kToolbarHeight) /
+                      (expandedHeight - kToolbarHeight);
+                  final showContent = collapseRatio > 0.3;
+
+                  return FlexibleSpaceBar(
+                    collapseMode: CollapseMode.pin,
+                    background: _buildHeaderBackground(
+                      context,
+                      colorScheme,
+                      expandedHeight,
+                      showContent,
+                    ),
+                    stretchModes: const [StretchMode.zoomBackground],
+                  );
+                },
+              ),
+              leading: IconButton(
+                tooltip: MaterialLocalizations.of(context).backButtonTooltip,
                 icon: Container(
                   padding: const EdgeInsets.all(8),
                   decoration: BoxDecoration(
                     color: Colors.black.withValues(alpha: 0.4),
                     shape: BoxShape.circle,
                   ),
-                  child: const Icon(Icons.more_vert, color: Colors.white),
+                  child: const Icon(Icons.arrow_back, color: Colors.white),
                 ),
-                onPressed: () => _showOptionsMenu(context, ref, colorScheme),
+                onPressed: _popWithMetadataResult,
               ),
-            ],
-          ),
-
-          SliverToBoxAdapter(
-            child: Padding(
-              padding: const EdgeInsets.all(16),
-              child: Column(
-                crossAxisAlignment: CrossAxisAlignment.start,
-                children: [
-                  _buildMetadataCard(context, colorScheme, _fileSize),
-
-                  const SizedBox(height: 16),
-
-                  _buildFileInfoCard(
-                    context,
-                    colorScheme,
-                    _fileExists,
-                    _fileSize,
+              actions: [
+                IconButton(
+                  tooltip: MaterialLocalizations.of(context).showMenuTooltip,
+                  icon: Container(
+                    padding: const EdgeInsets.all(8),
+                    decoration: BoxDecoration(
+                      color: Colors.black.withValues(alpha: 0.4),
+                      shape: BoxShape.circle,
+                    ),
+                    child: const Icon(Icons.more_vert, color: Colors.white),
                   ),
+                  onPressed: () => _showOptionsMenu(context, ref, colorScheme),
+                ),
+              ],
+            ),
 
-                  const SizedBox(height: 16),
+            SliverToBoxAdapter(
+              child: Padding(
+                padding: const EdgeInsets.all(16),
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    _buildMetadataCard(context, colorScheme, _fileSize),
 
-                  _buildLyricsCard(context, colorScheme),
-
-                  if (_fileExists) ...[
                     const SizedBox(height: 16),
-                    AudioAnalysisCard(filePath: _filePath),
+
+                    _buildFileInfoCard(
+                      context,
+                      colorScheme,
+                      _fileExists,
+                      _fileSize,
+                    ),
+
+                    const SizedBox(height: 16),
+
+                    _buildLyricsCard(context, colorScheme),
+
+                    if (_fileExists) ...[
+                      const SizedBox(height: 16),
+                      AudioAnalysisCard(filePath: _filePath),
+                    ],
+
+                    const SizedBox(height: 24),
+
+                    _buildActionButtons(context, ref, colorScheme, _fileExists),
+
+                    const SizedBox(height: 32),
                   ],
-
-                  const SizedBox(height: 24),
-
-                  _buildActionButtons(context, ref, colorScheme, _fileExists),
-
-                  const SizedBox(height: 32),
-                ],
+                ),
               ),
             ),
-          ),
-        ],
+          ],
+        ),
       ),
     );
   }
@@ -1255,8 +1400,12 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
       _MetadataItem(context.l10n.trackAlbum, albumName),
       if (trackNumber != null && trackNumber! > 0)
         _MetadataItem(context.l10n.trackTrackNumber, trackNumber.toString()),
+      if (totalTracks != null && totalTracks! > 0)
+        _MetadataItem('Track Total', totalTracks.toString()),
       if (discNumber != null && discNumber! > 0)
         _MetadataItem(context.l10n.trackDiscNumber, discNumber.toString()),
+      if (totalDiscs != null && totalDiscs! > 0)
+        _MetadataItem('Disc Total', totalDiscs.toString()),
       if (duration != null)
         _MetadataItem(context.l10n.trackDuration, _formatDuration(duration!)),
       if (audioQualityStr != null)
@@ -1269,6 +1418,8 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
         _MetadataItem(context.l10n.trackLabel, label!),
       if (copyright != null && copyright!.isNotEmpty)
         _MetadataItem(context.l10n.trackCopyright, copyright!),
+      if (composer != null && composer!.isNotEmpty)
+        _MetadataItem('Composer', composer!),
       if (isrc != null && isrc!.isNotEmpty) _MetadataItem('ISRC', isrc!),
     ];
 
@@ -2525,12 +2676,15 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
         'album_name': albumName,
         'album_artist': albumArtist ?? artistName,
         'track_number': trackNumber ?? 0,
+        'total_tracks': totalTracks ?? 0,
         'disc_number': discNumber ?? 0,
+        'total_discs': totalDiscs ?? 0,
         'release_date': releaseDate ?? '',
         'isrc': isrc ?? '',
         'genre': genre ?? '',
         'label': label ?? '',
         'copyright': copyright ?? '',
+        'composer': composer ?? '',
         'duration_ms': durationMs,
         'search_online': true,
       };
@@ -2548,11 +2702,14 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
             'album_artist': enriched['album_artist'] ?? albumArtist,
             'date': enriched['release_date'] ?? releaseDate,
             'track_number': enriched['track_number'] ?? trackNumber,
+            'total_tracks': enriched['total_tracks'] ?? totalTracks,
             'disc_number': enriched['disc_number'] ?? discNumber,
+            'total_discs': enriched['total_discs'] ?? totalDiscs,
             'isrc': enriched['isrc'] ?? isrc,
             'genre': enriched['genre'] ?? genre,
             'label': enriched['label'] ?? label,
             'copyright': enriched['copyright'] ?? copyright,
+            'composer': enriched['composer'] ?? composer,
           };
         });
       }
@@ -2721,9 +2878,12 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
             albumArtist: normalizedOrNull(albumArtist),
             isrc: normalizedOrNull(isrc),
             trackNumber: trackNumber,
+            totalTracks: totalTracks,
             discNumber: discNumber,
+            totalDiscs: totalDiscs,
             releaseDate: normalizedOrNull(releaseDate),
             genre: normalizedOrNull(genre),
+            composer: normalizedOrNull(composer),
             label: normalizedOrNull(label),
             copyright: normalizedOrNull(copyright),
           );
@@ -2989,19 +3149,29 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
   }
 
   Map<String, String> _buildFallbackMetadata() {
+    String formatIndexTag(int number, int? total) {
+      if (total != null && total > 0) {
+        return '$number/$total';
+      }
+      return number.toString();
+    }
+
     return {
       'TITLE': trackName,
       'ARTIST': artistName,
       'ALBUM': albumName,
       if (albumArtist != null && albumArtist!.isNotEmpty)
         'ALBUMARTIST': albumArtist!,
-      if (trackNumber != null) 'TRACKNUMBER': trackNumber.toString(),
-      if (discNumber != null) 'DISCNUMBER': discNumber.toString(),
+      if (trackNumber != null)
+        'TRACKNUMBER': formatIndexTag(trackNumber!, totalTracks),
+      if (discNumber != null)
+        'DISCNUMBER': formatIndexTag(discNumber!, totalDiscs),
       if (releaseDate != null && releaseDate!.isNotEmpty) 'DATE': releaseDate!,
       if (isrc != null && isrc!.isNotEmpty) 'ISRC': isrc!,
       if (genre != null && genre!.isNotEmpty) 'GENRE': genre!,
       if (label != null && label!.isNotEmpty) 'LABEL': label!,
       if (copyright != null && copyright!.isNotEmpty) 'COPYRIGHT': copyright!,
+      if (composer != null && composer!.isNotEmpty) 'COMPOSER': composer!,
     };
   }
 
@@ -3029,12 +3199,26 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
     put('UNSYNCEDLYRICS', source['lyrics']);
 
     final trackNumber = source['track_number'];
+    final totalTracks = source['total_tracks'];
     if (trackNumber != null && trackNumber.toString() != '0') {
-      put('TRACKNUMBER', trackNumber);
+      final trackTag =
+          totalTracks != null &&
+              totalTracks.toString().isNotEmpty &&
+              totalTracks.toString() != '0'
+          ? '${trackNumber.toString()}/${totalTracks.toString()}'
+          : trackNumber;
+      put('TRACKNUMBER', trackTag);
     }
     final discNumber = source['disc_number'];
+    final totalDiscs = source['total_discs'];
     if (discNumber != null && discNumber.toString() != '0') {
-      put('DISCNUMBER', discNumber);
+      final discTag =
+          totalDiscs != null &&
+              totalDiscs.toString().isNotEmpty &&
+              totalDiscs.toString() != '0'
+          ? '${discNumber.toString()}/${totalDiscs.toString()}'
+          : discNumber;
+      put('DISCNUMBER', discTag);
     }
 
     return mapped;
@@ -3859,8 +4043,50 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
       final newQuality = _buildConvertedQualityLabel(targetFormat, bitrate);
 
       if (isSaf) {
-        final treeUri = _downloadItem?.downloadTreeUri;
-        final relativeDir = _downloadItem?.safRelativeDir ?? '';
+        String? treeUri;
+        String relativeDir = '';
+        String oldFileName = '';
+        if (_isLocalItem) {
+          final uri = Uri.parse(cleanFilePath);
+          final pathSegments = uri.pathSegments;
+          final treeIdx = pathSegments.indexOf('tree');
+          final docIdx = pathSegments.indexOf('document');
+          if (treeIdx >= 0 && treeIdx + 1 < pathSegments.length) {
+            final treeId = pathSegments[treeIdx + 1];
+            treeUri =
+                'content://${uri.authority}/tree/${Uri.encodeComponent(treeId)}';
+          }
+          if (docIdx >= 0 && docIdx + 1 < pathSegments.length) {
+            final docPath = Uri.decodeFull(pathSegments[docIdx + 1]);
+            final slashIdx = docPath.lastIndexOf('/');
+            if (slashIdx >= 0) {
+              oldFileName = docPath.substring(slashIdx + 1);
+              final treeId = treeIdx >= 0 && treeIdx + 1 < pathSegments.length
+                  ? Uri.decodeFull(pathSegments[treeIdx + 1])
+                  : '';
+              if (treeId.isNotEmpty && docPath.startsWith(treeId)) {
+                final afterTree = docPath.substring(treeId.length);
+                final trimmed = afterTree.startsWith('/')
+                    ? afterTree.substring(1)
+                    : afterTree;
+                final lastSlash = trimmed.lastIndexOf('/');
+                relativeDir = lastSlash >= 0
+                    ? trimmed.substring(0, lastSlash)
+                    : '';
+              }
+            } else {
+              oldFileName = docPath;
+            }
+          }
+        } else {
+          treeUri = _downloadItem?.downloadTreeUri;
+          relativeDir = _downloadItem?.safRelativeDir ?? '';
+          oldFileName =
+              (_downloadItem?.safFileName != null &&
+                  _downloadItem!.safFileName!.isNotEmpty)
+              ? _downloadItem!.safFileName!
+              : _extractFileNameFromPathOrUri(cleanFilePath);
+        }
         if (treeUri == null || treeUri.isEmpty) {
           try {
             await File(newPath).delete();
@@ -3879,11 +4105,6 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
           return;
         }
 
-        final oldFileName =
-            (_downloadItem?.safFileName != null &&
-                _downloadItem!.safFileName!.isNotEmpty)
-            ? _downloadItem!.safFileName!
-            : _extractFileNameFromPathOrUri(cleanFilePath);
         final dotIdx = oldFileName.lastIndexOf('.');
         final baseName = dotIdx > 0
             ? oldFileName.substring(0, dotIdx)
@@ -3952,6 +4173,14 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
             clearAudioSpecs: true,
           );
           await ref.read(downloadHistoryProvider.notifier).reloadFromStorage();
+        } else {
+          await LibraryDatabase.instance.replaceWithConvertedItem(
+            item: _localLibraryItem!,
+            newFilePath: safUri,
+            targetFormat: targetFormat,
+            bitrate: bitrate,
+          );
+          await ref.read(localLibraryProvider.notifier).reloadFromStorage();
         }
 
         try {
@@ -3971,6 +4200,14 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
             clearAudioSpecs: true,
           );
           await ref.read(downloadHistoryProvider.notifier).reloadFromStorage();
+        } else {
+          await LibraryDatabase.instance.replaceWithConvertedItem(
+            item: _localLibraryItem!,
+            newFilePath: newPath,
+            targetFormat: targetFormat,
+            bitrate: bitrate,
+          );
+          await ref.read(localLibraryProvider.notifier).reloadFromStorage();
         }
       }
 
@@ -4021,13 +4258,17 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
       'date': val('date', releaseDate),
       'track_number': (fileMetadata?['track_number'] ?? trackNumber ?? '')
           .toString(),
+      'total_tracks': (fileMetadata?['total_tracks'] ?? totalTracks ?? '')
+          .toString(),
       'disc_number': (fileMetadata?['disc_number'] ?? discNumber ?? '')
           .toString(),
+      'total_discs': (fileMetadata?['total_discs'] ?? totalDiscs ?? '')
+          .toString(),
       'genre': val('genre', genre),
       'isrc': val('isrc', isrc),
       'label': val('label', label),
       'copyright': val('copyright', copyright),
-      'composer': fileMetadata?['composer']?.toString() ?? '',
+      'composer': val('composer', composer),
       'comment': fileMetadata?['comment']?.toString() ?? '',
     };
 
@@ -4314,11 +4555,14 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
     'album_artist': 'album_artist',
     'date': 'date',
     'track_number': 'track_number',
+    'total_tracks': 'total_tracks',
     'disc_number': 'disc_number',
+    'total_discs': 'total_discs',
     'genre': 'genre',
     'isrc': 'isrc',
     'label': 'label',
     'copyright': 'copyright',
+    'composer': 'composer',
     'cover': 'cover',
   };
 
@@ -4328,7 +4572,9 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
   late final TextEditingController _albumArtistCtrl;
   late final TextEditingController _dateCtrl;
   late final TextEditingController _trackNumCtrl;
+  late final TextEditingController _trackTotalCtrl;
   late final TextEditingController _discNumCtrl;
+  late final TextEditingController _discTotalCtrl;
   late final TextEditingController _genreCtrl;
   late final TextEditingController _isrcCtrl;
   late final TextEditingController _labelCtrl;
@@ -4516,8 +4762,12 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
         return l10n.editMetadataFieldDate;
       case 'track_number':
         return l10n.editMetadataFieldTrackNum;
+      case 'total_tracks':
+        return 'Track Total';
       case 'disc_number':
         return l10n.editMetadataFieldDiscNum;
+      case 'total_discs':
+        return 'Disc Total';
       case 'genre':
         return l10n.editMetadataFieldGenre;
       case 'isrc':
@@ -4526,6 +4776,8 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
         return l10n.editMetadataFieldLabel;
       case 'copyright':
         return l10n.editMetadataFieldCopyright;
+      case 'composer':
+        return 'Composer';
       case 'cover':
         return l10n.editMetadataFieldCover;
       default:
@@ -4547,8 +4799,12 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
         return _dateCtrl;
       case 'track_number':
         return _trackNumCtrl;
+      case 'total_tracks':
+        return _trackTotalCtrl;
       case 'disc_number':
         return _discNumCtrl;
+      case 'total_discs':
+        return _discTotalCtrl;
       case 'genre':
         return _genreCtrl;
       case 'isrc':
@@ -4557,6 +4813,8 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
         return _labelCtrl;
       case 'copyright':
         return _copyrightCtrl;
+      case 'composer':
+        return _composerCtrl;
       default:
         return null;
     }
@@ -4722,11 +4980,14 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
     put('album_artist', track['album_artist']);
     put('date', track['release_date']);
     put('track_number', track['track_number']);
+    put('total_tracks', track['total_tracks']);
     put('disc_number', track['disc_number']);
+    put('total_discs', track['total_discs']);
     put('isrc', track['isrc']);
     put('genre', track['genre']);
     put('label', track['label']);
     put('copyright', track['copyright']);
+    put('composer', track['composer']);
   }
 
   Future<_ResolvedAutoFillTrack?> _resolveAutoFillTrackFromIdentifiers(
@@ -4927,8 +5188,11 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
         'album_artist': (selectedBest['album_artist'] ?? '').toString(),
         'date': (selectedBest['release_date'] ?? '').toString(),
         'track_number': (selectedBest['track_number'] ?? '').toString(),
+        'total_tracks': (selectedBest['total_tracks'] ?? '').toString(),
         'disc_number': (selectedBest['disc_number'] ?? '').toString(),
+        'total_discs': (selectedBest['total_discs'] ?? '').toString(),
         'isrc': (selectedBest['isrc'] ?? '').toString(),
+        'composer': (selectedBest['composer'] ?? '').toString(),
       };
       _mergeOnlineTrackData(enriched, selectedBest);
 
@@ -4937,7 +5201,8 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
       final needsExtended =
           _autoFillFields.contains('genre') ||
           _autoFillFields.contains('label') ||
-          _autoFillFields.contains('copyright');
+          _autoFillFields.contains('copyright') ||
+          _autoFillFields.contains('composer');
 
       final rawSpotifyId = _extractRawSpotifyTrackId(selectedBest);
 
@@ -5099,7 +5364,9 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
     _albumArtistCtrl = TextEditingController(text: v['album_artist'] ?? '');
     _dateCtrl = TextEditingController(text: v['date'] ?? '');
     _trackNumCtrl = TextEditingController(text: v['track_number'] ?? '');
+    _trackTotalCtrl = TextEditingController(text: v['total_tracks'] ?? '');
     _discNumCtrl = TextEditingController(text: v['disc_number'] ?? '');
+    _discTotalCtrl = TextEditingController(text: v['total_discs'] ?? '');
     _genreCtrl = TextEditingController(text: v['genre'] ?? '');
     _isrcCtrl = TextEditingController(text: v['isrc'] ?? '');
     _labelCtrl = TextEditingController(text: v['label'] ?? '');
@@ -5119,7 +5386,9 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
     _albumArtistCtrl.dispose();
     _dateCtrl.dispose();
     _trackNumCtrl.dispose();
+    _trackTotalCtrl.dispose();
     _discNumCtrl.dispose();
+    _discTotalCtrl.dispose();
     _genreCtrl.dispose();
     _isrcCtrl.dispose();
     _labelCtrl.dispose();
@@ -5139,7 +5408,9 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
       'album_artist': _albumArtistCtrl.text,
       'date': _dateCtrl.text,
       'track_number': _trackNumCtrl.text,
+      'track_total': _trackTotalCtrl.text,
       'disc_number': _discNumCtrl.text,
+      'disc_total': _discTotalCtrl.text,
       'genre': _genreCtrl.text,
       'isrc': _isrcCtrl.text,
       'label': _labelCtrl.text,
@@ -5191,12 +5462,18 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
           'TRACKNUMBER':
               (metadata['track_number']?.isNotEmpty == true &&
                   metadata['track_number'] != '0')
-              ? metadata['track_number']!
+              ? (metadata['track_total']?.isNotEmpty == true &&
+                        metadata['track_total'] != '0'
+                    ? '${metadata['track_number']}/${metadata['track_total']}'
+                    : metadata['track_number']!)
               : '',
           'DISCNUMBER':
               (metadata['disc_number']?.isNotEmpty == true &&
                   metadata['disc_number'] != '0')
-              ? metadata['disc_number']!
+              ? (metadata['disc_total']?.isNotEmpty == true &&
+                        metadata['disc_total'] != '0'
+                    ? '${metadata['disc_number']}/${metadata['disc_total']}'
+                    : metadata['disc_number']!)
               : '',
           'GENRE': metadata['genre'] ?? '',
           'ISRC': metadata['isrc'] ?? '',
@@ -5409,6 +5686,18 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
                         ),
                       ),
                       const SizedBox(width: 12),
+                      Expanded(
+                        child: _field(
+                          'Track Total',
+                          _trackTotalCtrl,
+                          keyboard: TextInputType.number,
+                        ),
+                      ),
+                    ],
+                  ),
+                  const SizedBox(height: 12),
+                  Row(
+                    children: [
                       Expanded(
                         child: _field(
                           'Disc #',
@@ -5416,6 +5705,14 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
                           keyboard: TextInputType.number,
                         ),
                       ),
+                      const SizedBox(width: 12),
+                      Expanded(
+                        child: _field(
+                          'Disc Total',
+                          _discTotalCtrl,
+                          keyboard: TextInputType.number,
+                        ),
+                      ),
                     ],
                   ),
                   _field('Genre', _genreCtrl),

lib/services/download_request_payload.dart

@@ -17,6 +17,7 @@ class DownloadRequestPayload {
   final int trackNumber;
   final int discNumber;
   final int totalTracks;
+  final int totalDiscs;
   final String releaseDate;
   final String itemId;
   final int durationMs;
@@ -24,6 +25,7 @@ class DownloadRequestPayload {
   final String genre;
   final String label;
   final String copyright;
+  final String composer;
   final String tidalId;
   final String qobuzId;
   final String deezerId;
@@ -56,6 +58,7 @@ class DownloadRequestPayload {
     this.trackNumber = 0,
     this.discNumber = 0,
     this.totalTracks = 1,
+    this.totalDiscs = 0,
     this.releaseDate = '',
     this.itemId = '',
     this.durationMs = 0,
@@ -63,6 +66,7 @@ class DownloadRequestPayload {
     this.genre = '',
     this.label = '',
     this.copyright = '',
+    this.composer = '',
     this.tidalId = '',
     this.qobuzId = '',
     this.deezerId = '',
@@ -97,6 +101,7 @@ class DownloadRequestPayload {
       'track_number': trackNumber,
       'disc_number': discNumber,
       'total_tracks': totalTracks,
+      'total_discs': totalDiscs,
       'release_date': releaseDate,
       'item_id': itemId,
       'duration_ms': durationMs,
@@ -104,6 +109,7 @@ class DownloadRequestPayload {
       'genre': genre,
       'label': label,
       'copyright': copyright,
+      'composer': composer,
       'tidal_id': tidalId,
       'qobuz_id': qobuzId,
       'deezer_id': deezerId,
@@ -142,6 +148,7 @@ class DownloadRequestPayload {
       trackNumber: trackNumber,
       discNumber: discNumber,
       totalTracks: totalTracks,
+      totalDiscs: totalDiscs,
       releaseDate: releaseDate,
       itemId: itemId,
       durationMs: durationMs,
@@ -149,6 +156,7 @@ class DownloadRequestPayload {
       genre: genre,
       label: label,
       copyright: copyright,
+      composer: composer,
       tidalId: tidalId,
       qobuzId: qobuzId,
       deezerId: deezerId,

lib/services/ffmpeg_service.dart

@@ -13,6 +13,95 @@ import 'package:spotiflac_android/utils/logger.dart';
 
 final _log = AppLogger('FFmpeg');
 
+class DownloadDecryptionDescriptor {
+  final String strategy;
+  final String key;
+  final String? iv;
+  final String? inputFormat;
+  final String? outputExtension;
+  final Map<String, dynamic> options;
+
+  const DownloadDecryptionDescriptor({
+    required this.strategy,
+    required this.key,
+    this.iv,
+    this.inputFormat,
+    this.outputExtension,
+    this.options = const {},
+  });
+
+  factory DownloadDecryptionDescriptor.fromJson(Map<String, dynamic> json) {
+    final rawOptions = json['options'];
+    return DownloadDecryptionDescriptor(
+      strategy: (json['strategy'] as String? ?? '').trim(),
+      key: (json['key'] as String? ?? '').trim(),
+      iv: (json['iv'] as String?)?.trim(),
+      inputFormat: (json['input_format'] as String?)?.trim(),
+      outputExtension: (json['output_extension'] as String?)?.trim(),
+      options: rawOptions is Map
+          ? Map<String, dynamic>.from(rawOptions)
+          : const {},
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    final json = <String, dynamic>{'strategy': strategy, 'key': key};
+    if (iv != null && iv!.isNotEmpty) {
+      json['iv'] = iv;
+    }
+    if (inputFormat != null && inputFormat!.isNotEmpty) {
+      json['input_format'] = inputFormat;
+    }
+    if (outputExtension != null && outputExtension!.isNotEmpty) {
+      json['output_extension'] = outputExtension;
+    }
+    if (options.isNotEmpty) {
+      json['options'] = options;
+    }
+    return json;
+  }
+
+  static DownloadDecryptionDescriptor? fromDownloadResult(
+    Map<String, dynamic> result,
+  ) {
+    final rawDecryption = result['decryption'];
+    if (rawDecryption is Map) {
+      final descriptor = DownloadDecryptionDescriptor.fromJson(
+        Map<String, dynamic>.from(rawDecryption),
+      );
+      if (descriptor.normalizedStrategy == 'ffmpeg.mov_key' &&
+          descriptor.key.isNotEmpty) {
+        return descriptor;
+      }
+    }
+
+    final legacyKey = (result['decryption_key'] as String?)?.trim() ?? '';
+    if (legacyKey.isEmpty) {
+      return null;
+    }
+
+    return DownloadDecryptionDescriptor(
+      strategy: 'ffmpeg.mov_key',
+      key: legacyKey,
+      inputFormat: 'mov',
+    );
+  }
+
+  String get normalizedStrategy {
+    switch (strategy.trim().toLowerCase()) {
+      case '':
+      case 'ffmpeg.mov_key':
+      case 'ffmpeg_mov_key':
+      case 'mov_decryption_key':
+      case 'mp4_decryption_key':
+      case 'ffmpeg.mp4_decryption_key':
+        return 'ffmpeg.mov_key';
+      default:
+        return strategy.trim();
+    }
+  }
+}
+
 class FFmpegService {
   static const int _commandLogPreviewLength = 300;
   static const Duration _liveTunnelStartupTimeout = Duration(seconds: 8);
@@ -22,6 +111,7 @@ class FFmpegService {
   static const Duration _liveTunnelStabilizationDelay = Duration(
     milliseconds: 900,
   );
+  static const String _genericMovKeyDecryptionStrategy = 'ffmpeg.mov_key';
   static int _tempEmbedCounter = 0;
   static FFmpegSession? _activeLiveDecryptSession;
   static String? _activeLiveDecryptUrl;
@@ -216,12 +306,56 @@ class FFmpegService {
     required String decryptionKey,
     bool deleteOriginal = true,
   }) async {
-    final trimmedKey = decryptionKey.trim();
-    if (trimmedKey.isEmpty) return inputPath;
+    return decryptWithDescriptor(
+      inputPath: inputPath,
+      descriptor: DownloadDecryptionDescriptor(
+        strategy: _genericMovKeyDecryptionStrategy,
+        key: decryptionKey,
+        inputFormat: 'mov',
+      ),
+      deleteOriginal: deleteOriginal,
+    );
+  }
 
-    // Encrypted streams are commonly MP4 container with FLAC audio.
-    // Prefer FLAC output to avoid MP4 muxing errors during decrypt copy.
-    final preferredExt = inputPath.toLowerCase().endsWith('.m4a')
+  static Future<String?> decryptWithDescriptor({
+    required String inputPath,
+    required DownloadDecryptionDescriptor descriptor,
+    bool deleteOriginal = true,
+  }) async {
+    final key = descriptor.key.trim();
+
+    switch (descriptor.normalizedStrategy) {
+      case _genericMovKeyDecryptionStrategy:
+        if (key.isEmpty) {
+          return inputPath;
+        }
+        return _decryptMovKeyFile(
+          inputPath: inputPath,
+          decryptionKey: key,
+          inputFormat: descriptor.inputFormat,
+          outputExtension: descriptor.outputExtension,
+          deleteOriginal: deleteOriginal,
+        );
+      default:
+        _log.e(
+          'Unsupported download decryption strategy: ${descriptor.strategy}',
+        );
+        return null;
+    }
+  }
+
+  static String _resolvePreferredDecryptionExtension(
+    String inputPath,
+    String? requestedExtension,
+  ) {
+    final trimmedRequested = (requestedExtension ?? '').trim();
+    if (trimmedRequested.isNotEmpty) {
+      return trimmedRequested.startsWith('.')
+          ? trimmedRequested
+          : '.$trimmedRequested';
+    }
+
+    return inputPath.toLowerCase().endsWith('.m4a')
         ? '.flac'
         : inputPath.toLowerCase().endsWith('.flac')
         ? '.flac'
@@ -230,7 +364,23 @@ class FFmpegService {
         : inputPath.toLowerCase().endsWith('.opus')
         ? '.opus'
         : '.flac';
+  }
+
+  static Future<String?> _decryptMovKeyFile({
+    required String inputPath,
+    required String decryptionKey,
+    String? inputFormat,
+    String? outputExtension,
+    bool deleteOriginal = true,
+  }) async {
+    final preferredExt = _resolvePreferredDecryptionExtension(
+      inputPath,
+      outputExtension,
+    );
     var tempOutput = _buildOutputPath(inputPath, preferredExt);
+    final demuxerFormat = (inputFormat ?? '').trim().isNotEmpty
+        ? inputFormat!.trim()
+        : 'mov';
 
     String buildDecryptCommand(
       String outputPath, {
@@ -241,10 +391,10 @@ class FFmpegService {
       // Force MOV demuxer: -decryption_key is only supported by the MOV/MP4
       // demuxer. The input may carry a .flac extension (SAF mode) while actually
       // containing an encrypted M4A stream, so we must override auto-detection.
-      return '-v error -decryption_key "$key" -f mov -i "$inputPath" $audioMap-c copy "$outputPath" -y';
+      return '-v error -decryption_key "$key" -f $demuxerFormat -i "$inputPath" $audioMap-c copy "$outputPath" -y';
     }
 
-    final keyCandidates = _buildDecryptionKeyCandidates(trimmedKey);
+    final keyCandidates = _buildDecryptionKeyCandidates(decryptionKey);
     if (keyCandidates.isEmpty) {
       _log.e('No usable decryption key candidates');
       return null;
@@ -1311,28 +1461,38 @@ class FFmpegService {
     cmdBuffer.write('-v error -hide_banner ');
     cmdBuffer.write('-i "$m4aPath" ');
 
-    final hasCover = coverPath != null && await File(coverPath).exists();
+    final normalizedCoverPath = coverPath?.trim();
+    final hasCover =
+        normalizedCoverPath != null &&
+        normalizedCoverPath.isNotEmpty &&
+        await File(normalizedCoverPath).exists();
     if (hasCover) {
-      cmdBuffer.write('-i "$coverPath" ');
+      cmdBuffer.write('-i "$normalizedCoverPath" ');
     }
 
-    cmdBuffer.write('-map 0:a ');
+    final preserveExistingStreams = preserveMetadata && !hasCover;
+    if (preserveExistingStreams) {
+      // When no replacement cover is provided, preserve all input streams so
+      // the existing attached artwork is not dropped during the metadata rewrite.
+      cmdBuffer.write('-map 0 -c copy ');
+    } else {
+      cmdBuffer.write('-map 0:a -c:a copy ');
+    }
     cmdBuffer.write(
       preserveMetadata ? '-map_metadata 0 ' : '-map_metadata -1 ',
     );
 
-    // For M4A/MP4, cover art is mapped as a video stream and stored in the
-    // 'covr' atom automatically by FFmpeg. The '-disposition attached_pic'
-    // flag is only valid for Matroska/WebM containers and must NOT be used here.
-    // Force the mp4 muxer when cover art is present because the default ipod
-    // muxer (auto-selected for .m4a) does not register a codec tag for mjpeg,
-    // causing "codec not currently supported in container" on FFmpeg 8.0+.
+    // For M4A cover replacements, mark the image as an attached picture so the
+    // mp4 muxer writes a proper covr atom instead of a generic MJPEG video track.
+    // Force the mp4 muxer because the default ipod muxer (auto-selected for .m4a)
+    // does not register a codec tag for mjpeg on FFmpeg 8.0+.
     if (hasCover) {
-      cmdBuffer.write('-map 1:v -c:v copy -f mp4 ');
+      cmdBuffer.write('-map 1:v -c:v copy -disposition:v:0 attached_pic ');
+      cmdBuffer.write('-metadata:s:v title="Album cover" ');
+      cmdBuffer.write('-metadata:s:v comment="Cover (front)" ');
+      cmdBuffer.write('-f mp4 ');
     }
 
-    cmdBuffer.write('-c:a copy ');
-
     if (metadata != null) {
       final m4aMetadata = _convertToM4aTags(metadata);
       for (final entry in m4aMetadata.entries) {
@@ -1760,9 +1920,13 @@ class FFmpegService {
           if (value != '0') vorbis['DISCNUMBER'] = value;
           break;
         case 'DATE':
-        case 'YEAR':
           vorbis['DATE'] = value;
           break;
+        case 'YEAR':
+          if (!vorbis.containsKey('DATE') || vorbis['DATE']!.isEmpty) {
+            vorbis['DATE'] = value;
+          }
+          break;
         case 'GENRE':
           vorbis['GENRE'] = value;
           break;
@@ -1921,9 +2085,13 @@ class FFmpegService {
           m4aMap['disc'] = value;
           break;
         case 'DATE':
-        case 'YEAR':
           m4aMap['date'] = value;
           break;
+        case 'YEAR':
+          if (!m4aMap.containsKey('date') || m4aMap['date']!.isEmpty) {
+            m4aMap['date'] = value;
+          }
+          break;
         case 'GENRE':
           m4aMap['genre'] = value;
           break;
@@ -2004,9 +2172,13 @@ class FFmpegService {
           }
           break;
         case 'DATE':
-        case 'YEAR':
           id3Map['date'] = value;
           break;
+        case 'YEAR':
+          if (!id3Map.containsKey('date') || id3Map['date']!.isEmpty) {
+            id3Map['date'] = value;
+          }
+          break;
         case 'ISRC':
           id3Map['TSRC'] = value;
           break;

lib/services/history_database.dart

@@ -31,7 +31,7 @@ class HistoryDatabase {
 
     return await openDatabase(
       path,
-      version: 3,
+      version: 5,
       onConfigure: (db) async {
         await db.rawQuery('PRAGMA journal_mode = WAL');
         await db.execute('PRAGMA synchronous = NORMAL');
@@ -63,13 +63,16 @@ class HistoryDatabase {
         isrc TEXT,
         spotify_id TEXT,
         track_number INTEGER,
+        total_tracks INTEGER,
         disc_number INTEGER,
+        total_discs INTEGER,
         duration INTEGER,
         release_date TEXT,
         quality TEXT,
         bit_depth INTEGER,
         sample_rate INTEGER,
         genre TEXT,
+        composer TEXT,
         label TEXT,
         copyright TEXT
       )
@@ -98,6 +101,31 @@ class HistoryDatabase {
     if (oldVersion < 3) {
       await db.execute('ALTER TABLE history ADD COLUMN saf_repaired INTEGER');
     }
+    if (oldVersion < 4) {
+      final columns = await db.rawQuery('PRAGMA table_info(history)');
+      final hasComposer = columns.any(
+        (row) => (row['name']?.toString().toLowerCase() ?? '') == 'composer',
+      );
+      if (!hasComposer) {
+        await db.execute('ALTER TABLE history ADD COLUMN composer TEXT');
+      }
+    }
+    if (oldVersion < 5) {
+      final columns = await db.rawQuery('PRAGMA table_info(history)');
+      final hasTotalTracks = columns.any(
+        (row) =>
+            (row['name']?.toString().toLowerCase() ?? '') == 'total_tracks',
+      );
+      final hasTotalDiscs = columns.any(
+        (row) => (row['name']?.toString().toLowerCase() ?? '') == 'total_discs',
+      );
+      if (!hasTotalTracks) {
+        await db.execute('ALTER TABLE history ADD COLUMN total_tracks INTEGER');
+      }
+      if (!hasTotalDiscs) {
+        await db.execute('ALTER TABLE history ADD COLUMN total_discs INTEGER');
+      }
+    }
   }
 
   static final _iosContainerPattern = RegExp(
@@ -258,13 +286,16 @@ class HistoryDatabase {
       'isrc': json['isrc'],
       'spotify_id': json['spotifyId'],
       'track_number': json['trackNumber'],
+      'total_tracks': json['totalTracks'],
       'disc_number': json['discNumber'],
+      'total_discs': json['totalDiscs'],
       'duration': json['duration'],
       'release_date': json['releaseDate'],
       'quality': json['quality'],
       'bit_depth': json['bitDepth'],
       'sample_rate': json['sampleRate'],
       'genre': json['genre'],
+      'composer': json['composer'],
       'label': json['label'],
       'copyright': json['copyright'],
     };
@@ -289,13 +320,16 @@ class HistoryDatabase {
       'isrc': row['isrc'],
       'spotifyId': row['spotify_id'],
       'trackNumber': row['track_number'],
+      'totalTracks': row['total_tracks'],
       'discNumber': row['disc_number'],
+      'totalDiscs': row['total_discs'],
       'duration': row['duration'],
       'releaseDate': row['release_date'],
       'quality': row['quality'],
       'bitDepth': row['bit_depth'],
       'sampleRate': row['sample_rate'],
       'genre': row['genre'],
+      'composer': row['composer'],
       'label': row['label'],
       'copyright': row['copyright'],
     };

lib/services/library_database.dart

@@ -20,13 +20,18 @@ class LocalLibraryItem {
   final int? fileModTime;
   final String? isrc;
   final int? trackNumber;
+  final int? totalTracks;
   final int? discNumber;
+  final int? totalDiscs;
   final int? duration;
   final String? releaseDate;
   final int? bitDepth;
   final int? sampleRate;
   final int? bitrate; // kbps, for lossy formats (mp3, opus, ogg)
   final String? genre;
+  final String? composer;
+  final String? label;
+  final String? copyright;
   final String? format; // flac, mp3, opus, m4a
 
   const LocalLibraryItem({
@@ -41,13 +46,18 @@ class LocalLibraryItem {
     this.fileModTime,
     this.isrc,
     this.trackNumber,
+    this.totalTracks,
     this.discNumber,
+    this.totalDiscs,
     this.duration,
     this.releaseDate,
     this.bitDepth,
     this.sampleRate,
     this.bitrate,
     this.genre,
+    this.composer,
+    this.label,
+    this.copyright,
     this.format,
   });
 
@@ -63,13 +73,18 @@ class LocalLibraryItem {
     'fileModTime': fileModTime,
     'isrc': isrc,
     'trackNumber': trackNumber,
+    'totalTracks': totalTracks,
     'discNumber': discNumber,
+    'totalDiscs': totalDiscs,
     'duration': duration,
     'releaseDate': releaseDate,
     'bitDepth': bitDepth,
     'sampleRate': sampleRate,
     'bitrate': bitrate,
     'genre': genre,
+    'composer': composer,
+    'label': label,
+    'copyright': copyright,
     'format': format,
   };
 
@@ -85,14 +100,19 @@ class LocalLibraryItem {
         scannedAt: DateTime.parse(json['scannedAt'] as String),
         fileModTime: (json['fileModTime'] as num?)?.toInt(),
         isrc: json['isrc'] as String?,
-        trackNumber: json['trackNumber'] as int?,
-        discNumber: json['discNumber'] as int?,
-        duration: json['duration'] as int?,
+        trackNumber: (json['trackNumber'] as num?)?.toInt(),
+        totalTracks: (json['totalTracks'] as num?)?.toInt(),
+        discNumber: (json['discNumber'] as num?)?.toInt(),
+        totalDiscs: (json['totalDiscs'] as num?)?.toInt(),
+        duration: (json['duration'] as num?)?.toInt(),
         releaseDate: json['releaseDate'] as String?,
-        bitDepth: json['bitDepth'] as int?,
-        sampleRate: json['sampleRate'] as int?,
+        bitDepth: (json['bitDepth'] as num?)?.toInt(),
+        sampleRate: (json['sampleRate'] as num?)?.toInt(),
         bitrate: (json['bitrate'] as num?)?.toInt(),
         genre: json['genre'] as String?,
+        composer: json['composer'] as String?,
+        label: json['label'] as String?,
+        copyright: json['copyright'] as String?,
         format: json['format'] as String?,
       );
 
@@ -122,7 +142,7 @@ class LibraryDatabase {
 
     return await openDatabase(
       path,
-      version: 4,
+      version: 6,
       onConfigure: (db) async {
         await db.rawQuery('PRAGMA journal_mode = WAL');
         await db.execute('PRAGMA synchronous = NORMAL');
@@ -148,13 +168,18 @@ class LibraryDatabase {
         file_mod_time INTEGER,
         isrc TEXT,
         track_number INTEGER,
+        total_tracks INTEGER,
         disc_number INTEGER,
+        total_discs INTEGER,
         duration INTEGER,
         release_date TEXT,
         bit_depth INTEGER,
         sample_rate INTEGER,
         bitrate INTEGER,
         genre TEXT,
+        composer TEXT,
+        label TEXT,
+        copyright TEXT,
         format TEXT
       )
     ''');
@@ -190,6 +215,19 @@ class LibraryDatabase {
       await db.execute('ALTER TABLE library ADD COLUMN bitrate INTEGER');
       _log.i('Added bitrate column for lossy format quality');
     }
+
+    if (oldVersion < 5) {
+      await db.execute('ALTER TABLE library ADD COLUMN label TEXT');
+      await db.execute('ALTER TABLE library ADD COLUMN copyright TEXT');
+      _log.i('Added label/copyright columns');
+    }
+
+    if (oldVersion < 6) {
+      await db.execute('ALTER TABLE library ADD COLUMN total_tracks INTEGER');
+      await db.execute('ALTER TABLE library ADD COLUMN total_discs INTEGER');
+      await db.execute('ALTER TABLE library ADD COLUMN composer TEXT');
+      _log.i('Added total_tracks/total_discs/composer columns');
+    }
   }
 
   Map<String, dynamic> _jsonToDbRow(Map<String, dynamic> json) {
@@ -205,13 +243,18 @@ class LibraryDatabase {
       'file_mod_time': json['fileModTime'],
       'isrc': json['isrc'],
       'track_number': json['trackNumber'],
+      'total_tracks': json['totalTracks'],
       'disc_number': json['discNumber'],
+      'total_discs': json['totalDiscs'],
       'duration': json['duration'],
       'release_date': json['releaseDate'],
       'bit_depth': json['bitDepth'],
       'sample_rate': json['sampleRate'],
       'bitrate': json['bitrate'],
       'genre': json['genre'],
+      'composer': json['composer'],
+      'label': json['label'],
+      'copyright': json['copyright'],
       'format': json['format'],
     };
   }
@@ -229,13 +272,18 @@ class LibraryDatabase {
       'fileModTime': row['file_mod_time'],
       'isrc': row['isrc'],
       'trackNumber': row['track_number'],
+      'totalTracks': row['total_tracks'],
       'discNumber': row['disc_number'],
+      'totalDiscs': row['total_discs'],
       'duration': row['duration'],
       'releaseDate': row['release_date'],
       'bitDepth': row['bit_depth'],
       'sampleRate': row['sample_rate'],
       'bitrate': row['bitrate'],
       'genre': row['genre'],
+      'composer': row['composer'],
+      'label': row['label'],
+      'copyright': row['copyright'],
       'format': row['format'],
     };
   }
@@ -383,6 +431,45 @@ class LibraryDatabase {
     await db.delete('library', where: 'file_path = ?', whereArgs: [filePath]);
   }
 
+  Future<void> replaceWithConvertedItem({
+    required LocalLibraryItem item,
+    required String newFilePath,
+    required String targetFormat,
+    required String bitrate,
+  }) async {
+    final db = await database;
+    final stat = await fileStat(newFilePath);
+    final now = DateTime.now();
+    final normalizedFormat = _normalizeConvertedFormat(targetFormat);
+    final updated = item.toJson()
+      ..['id'] = _generateLibraryId(newFilePath)
+      ..['filePath'] = newFilePath
+      ..['scannedAt'] = now.toIso8601String()
+      ..['fileModTime'] = stat?.modified?.millisecondsSinceEpoch
+      ..['format'] = normalizedFormat
+      ..['bitrate'] = _convertedBitrate(
+        targetFormat: targetFormat,
+        bitrate: bitrate,
+      );
+
+    if (normalizedFormat == 'mp3' || normalizedFormat == 'opus') {
+      updated['bitDepth'] = null;
+    }
+
+    await db.transaction((txn) async {
+      await txn.delete(
+        'library',
+        where: 'id = ? OR file_path = ?',
+        whereArgs: [item.id, item.filePath],
+      );
+      await txn.insert(
+        'library',
+        _jsonToDbRow(updated),
+        conflictAlgorithm: ConflictAlgorithm.replace,
+      );
+    });
+  }
+
   Future<void> delete(String id) async {
     final db = await database;
     await db.delete('library', where: 'id = ?', whereArgs: [id]);
@@ -554,4 +641,43 @@ class LibraryDatabase {
     }
     return totalDeleted;
   }
+
+  String _normalizeConvertedFormat(String targetFormat) {
+    switch (targetFormat.trim().toLowerCase()) {
+      case 'alac':
+        return 'm4a';
+      case 'flac':
+        return 'flac';
+      case 'opus':
+        return 'opus';
+      default:
+        return 'mp3';
+    }
+  }
+
+  int? _convertedBitrate({
+    required String targetFormat,
+    required String bitrate,
+  }) {
+    switch (targetFormat.trim().toLowerCase()) {
+      case 'mp3':
+      case 'opus':
+        final match = RegExp(r'(\d+)').firstMatch(bitrate);
+        return match != null ? int.tryParse(match.group(1)!) : null;
+      default:
+        return null;
+    }
+  }
+
+  String _generateLibraryId(String filePath) {
+    return 'lib_${_hashString(filePath).toRadixString(16)}';
+  }
+
+  int _hashString(String input) {
+    var hash = 5381;
+    for (final codeUnit in input.codeUnits) {
+      hash = (((hash << 5) + hash) + codeUnit) & 0xffffffff;
+    }
+    return hash;
+  }
 }

lib/services/local_track_redownload_service.dart

@@ -142,8 +142,10 @@ class LocalTrackRedownloadService {
       duration: (durationMs / 1000).round(),
       trackNumber: data['track_number'] as int?,
       discNumber: data['disc_number'] as int?,
+      totalDiscs: data['total_discs'] as int?,
       releaseDate: data['release_date']?.toString(),
       totalTracks: data['total_tracks'] as int?,
+      composer: data['composer']?.toString(),
       source: data['source']?.toString() ?? data['provider_id']?.toString(),
       albumType: data['album_type']?.toString(),
       itemType: itemType,

lib/services/platform_bridge.dart

@@ -781,6 +781,15 @@ class PlatformBridge {
     return list.map((e) => e as String).toList();
   }
 
+  static Future<void> setDownloadFallbackExtensionIds(
+    List<String>? extensionIds,
+  ) async {
+    _log.d('setDownloadFallbackExtensionIds: $extensionIds');
+    await _channel.invokeMethod('setDownloadFallbackExtensionIds', {
+      'extension_ids': extensionIds == null ? '' : jsonEncode(extensionIds),
+    });
+  }
+
   static Future<void> setMetadataProviderPriority(
     List<String> providerIds,
   ) async {

lib/utils/lyrics_metadata_helper.dart

@@ -100,12 +100,28 @@ void mergePlatformMetadataForTagEmbed({
   put('UNSYNCEDLYRICS', source['lyrics']);
 
   final trackNumber = source['track_number'];
+  final totalTracks = source['total_tracks'];
   if (trackNumber != null && trackNumber.toString() != '0') {
-    put('TRACKNUMBER', trackNumber);
+    put(
+      'TRACKNUMBER',
+      totalTracks != null &&
+              totalTracks.toString().isNotEmpty &&
+              totalTracks.toString() != '0'
+          ? '${trackNumber.toString()}/${totalTracks.toString()}'
+          : trackNumber,
+    );
   }
 
   final discNumber = source['disc_number'];
+  final totalDiscs = source['total_discs'];
   if (discNumber != null && discNumber.toString() != '0') {
-    put('DISCNUMBER', discNumber);
+    put(
+      'DISCNUMBER',
+      totalDiscs != null &&
+              totalDiscs.toString().isNotEmpty &&
+              totalDiscs.toString() != '0'
+          ? '${discNumber.toString()}/${totalDiscs.toString()}'
+          : discNumber,
+    );
   }
 }

lib/widgets/animation_utils.dart

@@ -93,6 +93,35 @@ Route<T> slidePageRoute<T>({required Widget page}) {
   return MaterialPageRoute<T>(builder: (context) => page);
 }
 
+/// A directional horizontal transition for adjacent content, such as moving
+/// between next/previous items within the same detail context.
+Route<T> adjacentHorizontalPageRoute<T>({
+  required Widget page,
+  required bool fromRight,
+}) {
+  final begin = Offset(fromRight ? 0.22 : -0.22, 0);
+  return PageRouteBuilder<T>(
+    pageBuilder: (context, animation, secondaryAnimation) => page,
+    transitionDuration: const Duration(milliseconds: 240),
+    reverseTransitionDuration: const Duration(milliseconds: 220),
+    transitionsBuilder: (context, animation, secondaryAnimation, child) {
+      final curved = CurvedAnimation(
+        parent: animation,
+        curve: Curves.easeOutCubic,
+        reverseCurve: Curves.easeInCubic,
+      );
+
+      return SlideTransition(
+        position: Tween<Offset>(begin: begin, end: Offset.zero).animate(curved),
+        child: FadeTransition(
+          opacity: Tween<double>(begin: 0.92, end: 1.0).animate(curved),
+          child: child,
+        ),
+      );
+    },
+  );
+}
+
 /// A shimmer effect widget that can wrap skeleton placeholders.
 class ShimmerLoading extends StatefulWidget {
   final Widget child;

lib/widgets/download_service_picker.dart

@@ -64,17 +64,6 @@ const _builtInServices = [
       ),
     ],
   ),
-  BuiltInService(
-    id: 'deezer',
-    label: 'Deezer',
-    qualityOptions: [
-      QualityOption(
-        id: 'FLAC',
-        label: 'FLAC Best Quality',
-        description: 'Up to 24-bit / 48kHz+',
-      ),
-    ],
-  ),
 ];
 
 class DownloadServicePicker extends ConsumerStatefulWidget {
@@ -138,6 +127,18 @@ class _DownloadServicePickerState extends ConsumerState<DownloadServicePicker> {
     } else {
       _selectedService = ref.read(settingsProvider).defaultService;
     }
+    if (!_builtInServices.any((service) => service.id == _selectedService)) {
+      final extensionState = ref.read(extensionProvider);
+      final hasMatchingExtension = extensionState.extensions.any(
+        (ext) =>
+            ext.enabled &&
+            ext.hasDownloadProvider &&
+            ext.id == _selectedService,
+      );
+      if (!hasMatchingExtension) {
+        _selectedService = 'tidal';
+      }
+    }
   }
 
   List<QualityOption> _getQualityOptions() {

pubspec.yaml

@@ -1,7 +1,7 @@
 name: spotiflac_android
 description: Download Spotify tracks in FLAC from Tidal, Qobuz & Deezer
 publish_to: "none"
-version: 4.2.0+121
+version: 4.2.2+123
 
 environment:
   sdk: ^3.10.0