feat(extension): Enhanced HTTP API for YouTube Music support

- Add http.put(), http.delete(), http.patch() shortcut methods
- Add persistent cookie jar per extension
- Add http.clearCookies() to clear session
- Fix User-Agent header respect (no longer overwritten)
- Return multi-value headers as arrays (Set-Cookie support)
- Auto-stringify objects in POST/PUT/PATCH body
- Add response.ok and response.status properties
- Update documentation with YouTube Music example

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,123 @@
+name: Bug Report
+description: Report a bug or unexpected behavior
+title: "[Bug]: "
+labels: ["bug"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for taking the time to report a bug! Please fill out the form below.
+
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Checklist
+      description: Please confirm the following before submitting
+      options:
+        - label: I have searched existing issues and this bug hasn't been reported yet
+          required: true
+        - label: I am using the latest version of SpotiFLAC (Stable Version)
+          required: true
+
+  - type: textarea
+    id: description
+    attributes:
+      label: Bug Description
+      description: A clear and concise description of what the bug is
+      placeholder: Describe the bug...
+    validations:
+      required: true
+
+  - type: textarea
+    id: steps
+    attributes:
+      label: Steps to Reproduce
+      description: Steps to reproduce the behavior
+      placeholder: |
+        1. Go to '...'
+        2. Click on '...'
+        3. See error
+    validations:
+      required: true
+
+  - type: textarea
+    id: expected
+    attributes:
+      label: Expected Behavior
+      description: What did you expect to happen?
+      placeholder: Describe what you expected...
+    validations:
+      required: true
+
+  - type: textarea
+    id: actual
+    attributes:
+      label: Actual Behavior
+      description: What actually happened?
+      placeholder: Describe what actually happened...
+    validations:
+      required: true
+
+  - type: input
+    id: version
+    attributes:
+      label: App Version
+      description: Which version of SpotiFLAC are you using? (Check in Settings > About)
+      placeholder: "e.g., v2.2.0"
+    validations:
+      required: true
+
+  - type: dropdown
+    id: platform
+    attributes:
+      label: Platform
+      description: Which platform are you using?
+      options:
+        - Android
+        - iOS
+    validations:
+      required: true
+
+  - type: input
+    id: device
+    attributes:
+      label: Device & OS Version
+      description: What device and OS version are you using?
+      placeholder: "e.g., Samsung Galaxy S24, Android 14"
+    validations:
+      required: true
+
+  - type: dropdown
+    id: download-service
+    attributes:
+      label: Download Service
+      description: Which download service were you using when the bug occurred?
+      options:
+        - Tidal
+        - Qobuz
+        - Amazon Music
+        - Deezer (search only)
+        - Not applicable
+    validations:
+      required: true
+
+  - type: textarea
+    id: logs
+    attributes:
+      label: Logs / Screenshots
+      description: |
+        If applicable, add logs or screenshots to help explain your problem.
+        
+        **To get logs:**
+        1. Go to Settings > Options > Detailed Logging (turn ON)
+        2. Reproduce the bug
+        3. Go to Settings > Logs
+        4. Tap Share button to export logs
+      placeholder: Paste logs or drag & drop screenshots here...
+
+  - type: textarea
+    id: additional
+    attributes:
+      label: Additional Context
+      description: Any other context about the problem
+      placeholder: Add any other context...

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,8 @@
+blank_issues_enabled: false
+contact_links:
+  - name: README
+    url: https://github.com/zarzet/SpotiFLAC-Mobile#readme
+    about: Check the README for setup instructions and FAQ
+  - name: Extension Development Guide
+    url: https://zarz.moe/docs
+    about: Documentation for building SpotiFLAC extensions

.github/ISSUE_TEMPLATE/download_issue.yml

@@ -0,0 +1,111 @@
+name: Download Issue
+description: Report issues with downloading specific tracks or albums
+title: "[Download]: "
+labels: ["download-issue"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Having trouble downloading a specific track or album? Please provide details below.
+
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Checklist
+      description: Please confirm the following before submitting
+      options:
+        - label: I have tried downloading with a different service (Tidal/Qobuz/Amazon)
+          required: true
+        - label: I am using the latest version of SpotiFLAC (Stable Version)
+          required: true
+
+  - type: dropdown
+    id: issue-type
+    attributes:
+      label: Issue Type
+      description: What kind of download issue are you experiencing?
+      options:
+        - Track not found on service
+        - Wrong track downloaded
+        - Download fails/errors
+        - Metadata incorrect
+        - Audio quality issue
+        - Other
+    validations:
+      required: true
+
+  - type: input
+    id: spotify-url
+    attributes:
+      label: Spotify URL
+      description: The Spotify URL of the track/album you're trying to download
+      placeholder: "https://open.spotify.com/track/..."
+    validations:
+      required: true
+
+  - type: input
+    id: track-info
+    attributes:
+      label: Track Info
+      description: Artist name and track title
+      placeholder: "Artist - Track Title"
+    validations:
+      required: true
+
+  - type: dropdown
+    id: download-service
+    attributes:
+      label: Download Service
+      description: Which service did you try to download from?
+      options:
+        - Tidal
+        - Qobuz
+        - Amazon Music
+        - All services
+    validations:
+      required: true
+
+  - type: dropdown
+    id: search-service
+    attributes:
+      label: Search Service
+      description: Which search service are you using?
+      options:
+        - Spotify
+        - Deezer
+    validations:
+      required: true
+
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      description: Describe the issue in detail
+      placeholder: |
+        What happened? What did you expect?
+        If wrong track was downloaded, what track was downloaded instead?
+    validations:
+      required: true
+
+  - type: input
+    id: version
+    attributes:
+      label: App Version
+      description: Which version of SpotiFLAC are you using?
+      placeholder: "e.g., v2.2.0"
+    validations:
+      required: true
+
+  - type: textarea
+    id: screenshots
+    attributes:
+      label: Screenshots / Logs
+      description: |
+        If applicable, add screenshots or logs.
+        
+        **To get logs:**
+        1. Go to Settings > Options > Detailed Logging (turn ON)
+        2. Try downloading the track again
+        3. Go to Settings > Logs
+        4. Tap Share button to export logs
+      placeholder: Drag & drop screenshots or paste logs here...

.github/ISSUE_TEMPLATE/extension_feature_request.yml

@@ -0,0 +1,117 @@
+name: Extension API Feature Request
+description: Request new API features or capabilities for extension development
+title: "[Extension API]: "
+labels: ["enhancement", "extension-api"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for helping improve the SpotiFLAC Extension API! 
+        This form is for extension developers who need new features or capabilities that don't exist yet.
+
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Checklist
+      description: Please confirm the following before submitting
+      options:
+        - label: I have read the [Extension Development Guide](https://github.com/zarzet/SpotiFLAC-Mobile/blob/main/docs/EXTENSION_DEVELOPMENT.md)
+          required: true
+        - label: I have searched existing issues and this API feature hasn't been requested yet
+          required: true
+
+  - type: textarea
+    id: extension_goal
+    attributes:
+      label: What are you trying to build?
+      description: Describe the extension or feature you're developing
+      placeholder: "I'm building an extension that downloads from [service name] / provides metadata from [source]..."
+    validations:
+      required: true
+
+  - type: textarea
+    id: current_limitation
+    attributes:
+      label: Current API Limitation
+      description: What's missing or limiting in the current extension API?
+      placeholder: |
+        The current API doesn't support:
+        - [missing feature 1]
+        - [missing feature 2]
+        
+        This prevents me from...
+    validations:
+      required: true
+
+  - type: textarea
+    id: proposed_api
+    attributes:
+      label: Proposed API / Feature
+      description: Describe the API or feature you'd like to see added
+      placeholder: |
+        I would like to have:
+        - A new function `api.newFeature()` that does X
+        - A new manifest field `newOption` that enables Y
+        - Access to Z capability...
+    validations:
+      required: true
+
+  - type: textarea
+    id: use_case
+    attributes:
+      label: Use Case Example
+      description: Provide a code example of how you would use this feature
+      placeholder: |
+        ```javascript
+        // Example usage in extension code
+        function download(request, progressCallback) {
+          const result = api.proposedFeature(params);
+          // ...
+        }
+        ```
+    validations:
+      required: false
+
+  - type: dropdown
+    id: api_category
+    attributes:
+      label: API Category
+      description: What category does this feature fall under?
+      options:
+        - HTTP/Network API
+        - File System API
+        - Storage API
+        - FFmpeg/Audio Processing
+        - Manifest Options
+        - Runtime Functions
+        - UI Integration
+        - Authentication
+        - Other
+    validations:
+      required: true
+
+  - type: dropdown
+    id: priority
+    attributes:
+      label: How critical is this for your extension?
+      options:
+        - Blocker - Cannot build my extension without this
+        - High - Major functionality depends on this
+        - Medium - Would significantly improve my extension
+        - Low - Nice to have
+    validations:
+      required: true
+
+  - type: textarea
+    id: workaround
+    attributes:
+      label: Current Workaround
+      description: Are you using any workaround currently? If so, describe it.
+      placeholder: "Currently I'm working around this by..."
+
+  - type: textarea
+    id: additional
+    attributes:
+      label: Additional Context
+      description: Add any other context, links to similar APIs, or examples from other platforms
+      placeholder: "Similar feature in other platforms: ..."

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,66 @@
+name: Feature Request
+description: Suggest a new feature or improvement
+title: "[Feature]: "
+labels: ["enhancement"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for suggesting a feature! Please fill out the form below.
+
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Checklist
+      description: Please confirm the following before submitting
+      options:
+        - label: I have searched existing issues and this feature hasn't been requested yet
+          required: true
+
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem / Motivation
+      description: Is your feature request related to a problem? Please describe.
+      placeholder: "A clear description of what the problem is. Ex: I'm always frustrated when..."
+    validations:
+      required: true
+
+  - type: textarea
+    id: solution
+    attributes:
+      label: Proposed Solution
+      description: Describe the solution you'd like
+      placeholder: A clear description of what you want to happen...
+    validations:
+      required: true
+
+  - type: textarea
+    id: alternatives
+    attributes:
+      label: Alternatives Considered
+      description: Describe any alternative solutions or features you've considered
+      placeholder: Other approaches you've thought about...
+
+  - type: dropdown
+    id: category
+    attributes:
+      label: Category
+      description: What category does this feature fall under?
+      options:
+        - UI/UX Improvement
+        - Download Feature
+        - New Service Integration
+        - Metadata/Tagging
+        - Performance
+        - Settings/Configuration
+        - Other
+    validations:
+      required: true
+
+  - type: textarea
+    id: additional
+    attributes:
+      label: Additional Context
+      description: Add any other context, mockups, or screenshots about the feature request
+      placeholder: Add any other context or screenshots...

.github/workflows/release.yml

@@ -3,13 +3,13 @@ name: Release
 on:
   push:
     tags:
-      - 'v*'
+      - "v*"
   workflow_dispatch:
     inputs:
       version:
-        description: 'Version tag (e.g., v1.0.0)'
+        description: "Version tag (e.g., v1.0.0)"
         required: true
-        default: 'v1.0.0'
+        default: "v1.0.0"
 
 jobs:
   # Get version first (quick job)
@@ -17,35 +17,61 @@ jobs:
     runs-on: ubuntu-latest
     outputs:
       version: ${{ steps.version.outputs.version }}
+      is_prerelease: ${{ steps.version.outputs.is_prerelease }}
     steps:
       - name: Get version
         id: version
         run: |
           if [ "${{ github.event_name }}" = "workflow_dispatch" ]; then
-            echo "version=${{ github.event.inputs.version }}" >> $GITHUB_OUTPUT
+            VERSION="${{ github.event.inputs.version }}"
           else
-            echo "version=${GITHUB_REF#refs/tags/}" >> $GITHUB_OUTPUT
+            VERSION="${GITHUB_REF#refs/tags/}"
+          fi
+          echo "version=$VERSION" >> $GITHUB_OUTPUT
+
+          # Check if version contains -preview, -beta, -rc, or -alpha (NOT -hotfix)
+          VERSION_LOWER=$(echo "$VERSION" | tr '[:upper:]' '[:lower:]')
+          if [[ "$VERSION_LOWER" == *"-preview"* ]] || [[ "$VERSION_LOWER" == *"-beta"* ]] || [[ "$VERSION_LOWER" == *"-rc"* ]] || [[ "$VERSION_LOWER" == *"-alpha"* ]]; then
+            echo "is_prerelease=true" >> $GITHUB_OUTPUT
+            echo "Detected pre-release version: $VERSION"
+          else
+            echo "is_prerelease=false" >> $GITHUB_OUTPUT
+            echo "Detected stable version: $VERSION"
           fi
 
   # Android and iOS build in PARALLEL
   build-android:
     runs-on: ubuntu-latest
     needs: get-version
-    
+
     steps:
+      - name: Free disk space
+        run: |
+          # Remove large unused tools (~15GB total)
+          sudo rm -rf /usr/share/dotnet
+          sudo rm -rf /opt/ghc
+          sudo rm -rf /opt/hostedtoolcache/CodeQL
+          sudo rm -rf /usr/local/share/boost
+          sudo rm -rf /usr/share/swift
+          sudo rm -rf /usr/local/.ghcup
+          # Clean docker images
+          sudo docker image prune --all --force
+          # Show available space
+          df -h
+
       - name: Checkout repository
         uses: actions/checkout@v4
 
       - name: Setup Java
         uses: actions/setup-java@v4
         with:
-          distribution: 'temurin'
-          java-version: '17'
+          distribution: "temurin"
+          java-version: "17"
 
       - name: Setup Go
         uses: actions/setup-go@v5
         with:
-          go-version: '1.21'
+          go-version: "1.21"
           cache-dependency-path: go_backend/go.sum
 
       # Cache Gradle for faster builds
@@ -59,7 +85,20 @@ jobs:
           restore-keys: gradle-${{ runner.os }}-
 
       - name: Install Android SDK & NDK
-        uses: android-actions/setup-android@v3
+        run: |
+          # Use pre-installed Android SDK on GitHub runners
+          echo "ANDROID_HOME=$ANDROID_HOME"
+          echo "ANDROID_SDK_ROOT=$ANDROID_SDK_ROOT"
+
+          # Accept licenses
+          yes | $ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager --licenses || true
+
+          # Install NDK r27d LTS (required for 16KB page size support on Android 15+)
+          # Platform android-36 and build-tools 36.0.0 for targetSdk 36 (Android 16)
+          $ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager "ndk;27.3.13750724" "platforms;android-36" "build-tools;36.0.0"
+
+          # Set NDK path
+          echo "ANDROID_NDK_HOME=$ANDROID_HOME/ndk/27.3.13750724" >> $GITHUB_ENV
 
       - name: Install gomobile
         run: |
@@ -77,7 +116,7 @@ jobs:
       - name: Setup Flutter
         uses: subosito/flutter-action@v2
         with:
-          channel: 'stable'
+          channel: "stable"
           cache: true
 
       - name: Get Flutter dependencies
@@ -87,7 +126,14 @@ jobs:
         run: dart run flutter_launcher_icons
 
       - name: Build APK (Release - unsigned)
-        run: flutter build apk --release --split-per-abi
+        run: |
+          flutter build apk --release --split-per-abi || true
+          # Verify APKs were created
+          ls -la build/app/outputs/flutter-apk/
+          if [ ! -f "build/app/outputs/flutter-apk/app-arm64-v8a-release.apk" ]; then
+            echo "ERROR: APK not found!"
+            exit 1
+          fi
 
       - name: Sign APKs
         uses: r0adkll/sign-android-release@v1
@@ -99,7 +145,7 @@ jobs:
           keyStorePassword: ${{ secrets.KEYSTORE_PASSWORD }}
           keyPassword: ${{ secrets.KEY_PASSWORD }}
         env:
-          BUILD_TOOLS_VERSION: "34.0.0"
+          BUILD_TOOLS_VERSION: "36.0.0"
 
       - name: Rename APKs
         run: |
@@ -119,8 +165,8 @@ jobs:
 
   build-ios:
     runs-on: macos-latest
-    needs: get-version  # Only depends on version, NOT android build!
-    
+    needs: get-version # Only depends on version, NOT android build!
+
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
@@ -128,7 +174,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@v5
         with:
-          go-version: '1.21'
+          go-version: "1.21"
           cache-dependency-path: go_backend/go.sum
 
       # Cache CocoaPods
@@ -156,53 +202,70 @@ jobs:
         run: |
           ls -la ios/Frameworks/
           ls -la ios/Frameworks/Gobackend.xcframework/ || (echo "ERROR: XCFramework not found!" && exit 1)
-          
+
       - name: Add XCFramework to Xcode project
         run: |
           # Install xcodeproj gem for modifying Xcode project
           sudo gem install xcodeproj
-          
+
           # Create Ruby script to add framework
           cat > add_framework.rb << 'EOF'
           require 'xcodeproj'
-          
+
           project_path = 'ios/Runner.xcodeproj'
           project = Xcodeproj::Project.open(project_path)
-          
+
           # Get the main target
           target = project.targets.find { |t| t.name == 'Runner' }
-          
+
           # Get or create Frameworks group
           frameworks_group = project.main_group.find_subpath('Frameworks', true)
           frameworks_group ||= project.main_group.new_group('Frameworks')
-          
+
           # Add XCFramework reference
           framework_path = 'Frameworks/Gobackend.xcframework'
           framework_ref = frameworks_group.new_file(framework_path, :project)
-          
+
           # Add to frameworks build phase
           frameworks_build_phase = target.frameworks_build_phase
           frameworks_build_phase.add_file_reference(framework_ref)
-          
+
           # Add to embed frameworks build phase
           embed_phase = target.build_phases.find { |p| p.is_a?(Xcodeproj::Project::Object::PBXCopyFilesBuildPhase) && p.name == 'Embed Frameworks' }
           if embed_phase
             build_file = embed_phase.add_file_reference(framework_ref)
             build_file.settings = { 'ATTRIBUTES' => ['CodeSignOnCopy', 'RemoveHeadersOnCopy'] }
           end
-          
+
           project.save
           puts "Successfully added Gobackend.xcframework to Xcode project"
           EOF
-          
+
           ruby add_framework.rb
 
       - name: Setup Flutter
         uses: subosito/flutter-action@v2
         with:
-          channel: 'stable'
+          channel: "stable"
           cache: true
 
+      # Swap pubspec for iOS build (includes ffmpeg_kit_flutter)
+      - name: Use iOS pubspec with FFmpeg plugin
+        run: |
+          cp pubspec.yaml pubspec_android_backup.yaml
+          cp pubspec_ios.yaml pubspec.yaml
+          echo "Swapped to iOS pubspec with ffmpeg_kit_flutter"
+
+      # Swap FFmpeg service for iOS
+      - name: Use iOS FFmpeg service
+        run: |
+          cp lib/services/ffmpeg_service.dart lib/services/ffmpeg_service_android.dart
+          cp build_assets/ffmpeg_service_ios.dart lib/services/ffmpeg_service.dart
+          # Update class name in the swapped file
+          sed -i '' 's/FFmpegServiceIOS/FFmpegService/g' lib/services/ffmpeg_service.dart
+          sed -i '' 's/FFmpegResultIOS/FFmpegResult/g' lib/services/ffmpeg_service.dart
+          echo "Swapped to iOS FFmpeg service"
+
       - name: Get Flutter dependencies
         run: flutter pub get
 
@@ -210,18 +273,44 @@ jobs:
         run: dart run flutter_launcher_icons
 
       - name: Build iOS (unsigned)
-        run: flutter build ios --release --no-codesign
+        run: |
+          # Build Flutter iOS without codesigning
+          flutter build ios --release --no-codesign --config-only
+
+          # Use xcodebuild with code signing disabled
+          cd ios
+          xcodebuild -workspace Runner.xcworkspace \
+            -scheme Runner \
+            -configuration Release \
+            -sdk iphoneos \
+            -destination 'generic/platform=iOS' \
+            -archivePath build/Runner.xcarchive \
+            archive \
+            CODE_SIGNING_ALLOWED=NO \
+            CODE_SIGNING_REQUIRED=NO \
+            CODE_SIGN_IDENTITY="" \
+            DEVELOPMENT_TEAM=""
 
       - name: Create IPA
         run: |
           VERSION=${{ needs.get-version.outputs.version }}
           mkdir -p build/ios/ipa
-          cd build/ios/iphoneos
+          cd ios/build/Runner.xcarchive/Products/Applications
           mkdir Payload
           cp -r Runner.app Payload/
-          zip -r ../ipa/SpotiFLAC-${VERSION}-ios-unsigned.ipa Payload
+          # Use absolute path to avoid relative path issues
+          zip -r $GITHUB_WORKSPACE/build/ios/ipa/SpotiFLAC-${VERSION}-ios-unsigned.ipa Payload
           rm -rf Payload
 
+      - name: Verify IPA created
+        run: |
+          ls -la build/ios/ipa/
+          VERSION=${{ needs.get-version.outputs.version }}
+          if [ ! -f "build/ios/ipa/SpotiFLAC-${VERSION}-ios-unsigned.ipa" ]; then
+            echo "ERROR: IPA not created!"
+            exit 1
+          fi
+
       - name: Upload IPA artifact
         uses: actions/upload-artifact@v4
         with:
@@ -233,7 +322,7 @@ jobs:
     needs: [get-version, build-android, build-ios]
     permissions:
       contents: write
-    
+
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
@@ -243,13 +332,13 @@ jobs:
         run: |
           VERSION=${{ needs.get-version.outputs.version }}
           VERSION_NUM=${VERSION#v}  # Remove 'v' prefix
-          
+
           echo "Looking for version: $VERSION_NUM"
-          
+
           # Extract changelog section for this version using sed
           # Find the line with version, then print until next version header or end
           CHANGELOG=$(sed -n "/^## \[$VERSION_NUM\]/,/^## \[/{ /^## \[$VERSION_NUM\]/d; /^## \[/d; p; }" CHANGELOG.md)
-          
+
           # If no changelog found, use default message
           if [ -z "$CHANGELOG" ]; then
             echo "No changelog found for version $VERSION_NUM"
@@ -257,7 +346,7 @@ jobs:
           else
             echo "Found changelog content"
           fi
-          
+
           # Save to file for multiline support
           echo "$CHANGELOG" > /tmp/changelog.txt
           echo "Extracted changelog:"
@@ -279,32 +368,34 @@ jobs:
         run: |
           VERSION=${{ needs.get-version.outputs.version }}
           cat > /tmp/release_body.txt << 'HEADER'
-          ## SpotiFLAC $VERSION
-          
-          Download Spotify tracks in FLAC quality from Tidal, Qobuz & Amazon Music.
-          
           ### What's New
           HEADER
-          
-          # Replace $VERSION in header
-          sed -i "s/\$VERSION/$VERSION/g" /tmp/release_body.txt
-          
+
           cat /tmp/changelog.txt >> /tmp/release_body.txt
+
+          REPO_OWNER="${{ github.repository_owner }}"
+          REPO_NAME="${{ github.event.repository.name }}"
           
           cat >> /tmp/release_body.txt << FOOTER
-          
+
           ---
-          
+
           ### Downloads
-          - **Android (arm64)**: \`SpotiFLAC-${VERSION}-arm64.apk\` (recommended)
-          - **Android (arm32)**: \`SpotiFLAC-${VERSION}-arm32.apk\` (older devices)
+
+          #### Android
+          - **arm64**: \`SpotiFLAC-${VERSION}-arm64.apk\` (recommended for modern devices)
+          - **arm32**: \`SpotiFLAC-${VERSION}-arm32.apk\` (older devices)
+
+          #### iOS
           - **iOS**: \`SpotiFLAC-${VERSION}-ios-unsigned.ipa\` (sideload required)
-          
+
           ### Installation
           **Android**: Enable "Install from unknown sources" and install the APK
           **iOS**: Use AltStore, Sideloadly, or similar tools to sideload the IPA
+
+          ![arm64](https://img.shields.io/github/downloads/${REPO_OWNER}/${REPO_NAME}/${VERSION}/SpotiFLAC-${VERSION}-arm64.apk?style=flat-square&logo=android&label=arm64&color=3DDC84) ![arm32](https://img.shields.io/github/downloads/${REPO_OWNER}/${REPO_NAME}/${VERSION}/SpotiFLAC-${VERSION}-arm32.apk?style=flat-square&logo=android&label=arm32&color=3DDC84) ![iOS](https://img.shields.io/github/downloads/${REPO_OWNER}/${REPO_NAME}/${VERSION}/SpotiFLAC-${VERSION}-ios-unsigned.ipa?style=flat-square&logo=apple&label=iOS&color=0078D6)
           FOOTER
-          
+
           echo "Release body:"
           cat /tmp/release_body.txt
 
@@ -316,6 +407,6 @@ jobs:
           body_path: /tmp/release_body.txt
           files: ./release/*
           draft: false
-          prerelease: false
+          prerelease: ${{ needs.get-version.outputs.is_prerelease == 'true' }}
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -13,8 +13,8 @@ Thumbs.db
 # Reference folder (development only)
 referensi/
 
-# Development notes
-COMPARISON_PC_vs_ANDROID.md
+# Documentation (development only, published separately)
+docs/
 
 # Old spotiflac_android folder (moved to root)
 spotiflac_android/
@@ -38,7 +38,7 @@ go_backend/*.xcframework/
 
 # Android
 android/.gradle/
-android/app/libs/
+android/app/libs/gobackend.aar
 android/local.properties
 android/*.iml
 android/key.properties
@@ -52,3 +52,4 @@ ios/Pods/
 ios/.symlinks/
 ios/Flutter/Flutter.framework/
 ios/Flutter/Flutter.podspec
+android/app/libs/gobackend-sources.jar

README.md

@@ -1,4 +1,5 @@
 [![GitHub All Releases](https://img.shields.io/github/downloads/zarzet/SpotiFLAC-Mobile/total?style=for-the-badge)](https://github.com/zarzet/SpotiFLAC-Mobile/releases)
+[![VirusTotal](https://img.shields.io/badge/VirusTotal-Safe-brightgreen?style=for-the-badge&logo=virustotal)](https://www.virustotal.com/gui/file/09c6260e9ebaf2ff0d15f30deda939642f41887f11aad602ac697cb37fa0308c/)
 
 <div align="center">
 
@@ -13,33 +14,67 @@ Get Spotify tracks in true FLAC from Tidal, Qobuz & Amazon Music — no account
 
 ### [Download](https://github.com/zarzet/SpotiFLAC-Mobile/releases)
 
-## Features
-
-- Download tracks, albums, and playlists from Spotify links
-- True lossless FLAC quality from Tidal, Qobuz & Amazon Music
-- Material Expressive 3 design with dynamic colors
-- High performance rendering with Impeller (Vulkan)
-- Concurrent downloads up to 3 simultaneous
-- Real-time download progress tracking
-- Download notifications
-
 ## Screenshots
 
 <p align="center">
-  <img src="assets/images/1.jpg" width="200" />
-  <img src="assets/images/2.jpg" width="200" />
-  <img src="assets/images/3.jpg" width="200" />
-  <img src="assets/images/4.jpg" width="200" />
+  <img src="assets/images/1.jpg?v=2" width="200" />
+  <img src="assets/images/2.jpg?v=2" width="200" />
+  <img src="assets/images/3.jpg?v=2" width="200" />
+  <img src="assets/images/4.jpg?v=2" width="200" />
 </p>
 
+## Metadata Source
+
+SpotiFLAC supports two metadata sources for searching tracks:
+
+| Source | Pros | Cons |
+|--------|------|------|
+| **Deezer** (Default) | No developer account needed, rate limit per user IP | Slightly less comprehensive catalog |
+| **Spotify** | More comprehensive catalog, better search results | Requires developer API credentials to avoid rate limiting |
+
+### Using Spotify
+To use Spotify as your search source without hitting rate limits:
+1. Create a Spotify Developer account at [developer.spotify.com](https://developer.spotify.com)
+2. Create an app to get your Client ID and Client Secret
+3. Go to **Settings > Options > Spotify API > Change from Deezer to Spotify > Input Custom Credentials**
+4. Enter your Client ID and Secret
+5. Change **Search Source** to Spotify
+
+## Extensions (Alpha)
+
+> **Alpha Feature**: Extensions are now available in alpha. Some features may be unstable or change in future releases.
+
+SpotiFLAC supports extensions to add custom metadata and download providers. Extensions are written in JavaScript and run in a secure sandbox.
+
+### Features
+- **Metadata Providers**: Add new sources for track/album/artist search
+- **Download Providers**: Add new sources for audio downloads
+- **Custom Settings**: Extensions can have user-configurable settings
+- **Provider Priority**: Set the order in which providers are tried
+
+### Installing Extensions
+1. Download a `.spotiflac-ext` file
+2. Go to **Settings > Extensions**
+3. Tap **Install Extension** and select the file
+4. Configure extension settings if needed
+5. Set provider priority in **Settings > Extensions > Provider Priority**
+
+### Developing Extensions
+Want to create your own extension? Check out the [Extension Development Guide](docs/EXTENSION_DEVELOPMENT.md) for complete documentation.
+
+### Example Extensions
+Sample extensions are available in the [docs/extensions_example](docs/extensions_example) folder:
+
 ## Other project
 
 ### [SpotiFLAC (Desktop)](https://github.com/afkarxyz/SpotiFLAC)
 Get Spotify tracks in true FLAC from Tidal, Qobuz & Amazon Music for Windows, macOS & Linux
 
+[![Ko-fi](https://img.shields.io/badge/Ko--fi-Support%20Me-FF5E5B?style=for-the-badge&logo=ko-fi&logoColor=white)](https://ko-fi.com/zarzet)
+
 ## Disclaimer
 
-> **📱 iOS Support**: This app is primarily tested on Android. iOS support is experimental and may have bugs — the developer is too poor to afford an iPhone for proper testing. If you encounter issues on iOS, please report them!
+> **iOS Support**: This app is primarily tested on Android. iOS support is experimental and may have bugs — the developer is too poor to afford an iPhone for proper testing. If you encounter issues on iOS, please report them!
 
 This project is for **educational and private use only**. The developer does not condone or encourage copyright infringement.
 

android/app/build.gradle.kts

@@ -1,3 +1,6 @@
+import java.util.Properties
+import java.io.FileInputStream
+
 plugins {
     id("com.android.application")
     id("kotlin-android")
@@ -7,9 +10,9 @@ plugins {
 
 // Load keystore properties for local builds
 val keystorePropertiesFile = rootProject.file("key.properties")
-val keystoreProperties = java.util.Properties()
+val keystoreProperties = Properties()
 if (keystorePropertiesFile.exists()) {
-    keystoreProperties.load(java.io.FileInputStream(keystorePropertiesFile))
+    keystoreProperties.load(FileInputStream(keystorePropertiesFile))
 }
 
 android {
@@ -32,10 +35,10 @@ android {
     signingConfigs {
         if (keystorePropertiesFile.exists()) {
             create("release") {
-                keyAlias = keystoreProperties["keyAlias"] as String
-                keyPassword = keystoreProperties["keyPassword"] as String
-                storeFile = file(keystoreProperties["storeFile"] as String)
-                storePassword = keystoreProperties["storePassword"] as String
+                keyAlias = keystoreProperties.getProperty("keyAlias")
+                keyPassword = keystoreProperties.getProperty("keyPassword")
+                storeFile = file(keystoreProperties.getProperty("storeFile"))
+                storePassword = keystoreProperties.getProperty("storePassword")
             }
         }
     }
@@ -43,7 +46,7 @@ android {
     defaultConfig {
         applicationId = "com.zarz.spotiflac"
         minSdk = flutter.minSdkVersion
-        targetSdk = 34
+        targetSdk = 36
         versionCode = flutter.versionCode
         versionName = flutter.versionName
         multiDexEnabled = true
@@ -94,7 +97,10 @@ repositories {
 
 dependencies {
     coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.1.4")
-    implementation(files("libs/gobackend.aar"))
+    
+    // Include all AAR and JAR files from libs folder
+    implementation(fileTree(mapOf("dir" to "libs", "include" to listOf("*.jar", "*.aar"))))
+    
     implementation("org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3")
     implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.7.0")
 }

android/app/proguard-rules.pro

@@ -6,6 +6,14 @@
 -keep class io.flutter.** { *; }
 -keep class io.flutter.plugins.** { *; }
 
+# Ignore missing Play Core classes (not used, but referenced by Flutter)
+-dontwarn com.google.android.play.core.splitcompat.**
+-dontwarn com.google.android.play.core.splitinstall.**
+-dontwarn com.google.android.play.core.tasks.**
+
+# Ignore missing javax.xml.stream (not used on Android)
+-dontwarn javax.xml.stream.**
+
 # Go backend (gobackend.aar)
 -keep class gobackend.** { *; }
 -keep class go.** { *; }
@@ -14,6 +22,9 @@
 -keep class com.arthenica.ffmpegkit.** { *; }
 -keep class com.arthenica.smartexception.** { *; }
 
+# Apache Tika (if used by FFmpeg)
+-dontwarn org.apache.tika.**
+
 # Keep native methods
 -keepclasseswithmembernames class * {
     native <methods>;

android/app/src/main/AndroidManifest.xml

@@ -4,27 +4,30 @@
     <!-- Permissions -->
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" 
-        android:maxSdkVersion="28" />
+        android:maxSdkVersion="29" />
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" 
         android:maxSdkVersion="32" />
+    <!-- For Android 11+ (API 30-32) - full storage access -->
+    <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" />
     <uses-permission android:name="android.permission.READ_MEDIA_AUDIO" />
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC" />
     <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
     <uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" />
+    <uses-permission android:name="android.permission.WAKE_LOCK" />
 
     <application
         android:label="SpotiFLAC"
         android:name="${applicationName}"
         android:icon="@mipmap/ic_launcher"
         android:requestLegacyExternalStorage="true"
-        android:usesCleartextTraffic="true">
+        android:usesCleartextTraffic="true"
+        android:enableOnBackInvokedCallback="true">
 
         <activity
             android:name=".MainActivity"
             android:exported="true"
-            android:launchMode="singleTop"
-            android:taskAffinity=""
+            android:launchMode="singleTask"
             android:theme="@style/LaunchTheme"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
             android:hardwareAccelerated="true"

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

@@ -5,83 +5,227 @@ import android.app.NotificationChannel
 import android.app.NotificationManager
 import android.app.PendingIntent
 import android.app.Service
+import android.content.Context
 import android.content.Intent
 import android.os.Build
 import android.os.IBinder
+import android.os.PowerManager
 import androidx.core.app.NotificationCompat
 
+/**
+ * Foreground service to keep downloads running when app is in background.
+ * This prevents Android from killing the download process or throttling network.
+ * 
+ * Note: Android 15+ (API 35+) has a 6-hour timeout for dataSync foreground services.
+ * The service will be stopped automatically after 6 hours of cumulative runtime in 24 hours.
+ */
 class DownloadService : Service() {
+    
     companion object {
-        const val CHANNEL_ID = "spotiflac_download_channel"
-        const val NOTIFICATION_ID = 1
-        const val ACTION_START = "com.zarz.spotiflac.START_DOWNLOAD"
-        const val ACTION_STOP = "com.zarz.spotiflac.STOP_DOWNLOAD"
+        private const val CHANNEL_ID = "download_channel"
+        private const val NOTIFICATION_ID = 1001
+        private const val WAKELOCK_TAG = "SpotiFLAC:DownloadWakeLock"
+        
+        const val ACTION_START = "com.zarz.spotiflac.action.START_DOWNLOAD"
+        const val ACTION_STOP = "com.zarz.spotiflac.action.STOP_DOWNLOAD"
+        const val ACTION_UPDATE_PROGRESS = "com.zarz.spotiflac.action.UPDATE_PROGRESS"
+        
+        const val EXTRA_TRACK_NAME = "track_name"
+        const val EXTRA_ARTIST_NAME = "artist_name"
+        const val EXTRA_PROGRESS = "progress"
+        const val EXTRA_TOTAL = "total"
+        const val EXTRA_QUEUE_COUNT = "queue_count"
+        
+        private var isRunning = false
+        
+        fun isServiceRunning(): Boolean = isRunning
+        
+        fun start(context: Context, trackName: String = "", artistName: String = "", queueCount: Int = 0) {
+            val intent = Intent(context, DownloadService::class.java).apply {
+                action = ACTION_START
+                putExtra(EXTRA_TRACK_NAME, trackName)
+                putExtra(EXTRA_ARTIST_NAME, artistName)
+                putExtra(EXTRA_QUEUE_COUNT, queueCount)
+            }
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+        
+        fun stop(context: Context) {
+            val intent = Intent(context, DownloadService::class.java).apply {
+                action = ACTION_STOP
+            }
+            context.startService(intent)
+        }
+        
+        fun updateProgress(context: Context, trackName: String, artistName: String, progress: Long, total: Long, queueCount: Int) {
+            val intent = Intent(context, DownloadService::class.java).apply {
+                action = ACTION_UPDATE_PROGRESS
+                putExtra(EXTRA_TRACK_NAME, trackName)
+                putExtra(EXTRA_ARTIST_NAME, artistName)
+                putExtra(EXTRA_PROGRESS, progress)
+                putExtra(EXTRA_TOTAL, total)
+                putExtra(EXTRA_QUEUE_COUNT, queueCount)
+            }
+            context.startService(intent)
+        }
     }
-
+    
+    private var wakeLock: PowerManager.WakeLock? = null
+    private var currentTrackName = ""
+    private var currentArtistName = ""
+    private var queueCount = 0
+    
     override fun onCreate() {
         super.onCreate()
         createNotificationChannel()
     }
-
+    
     override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
         when (intent?.action) {
-            ACTION_START -> startForegroundService()
-            ACTION_STOP -> stopSelf()
+            ACTION_START -> {
+                currentTrackName = intent.getStringExtra(EXTRA_TRACK_NAME) ?: ""
+                currentArtistName = intent.getStringExtra(EXTRA_ARTIST_NAME) ?: ""
+                queueCount = intent.getIntExtra(EXTRA_QUEUE_COUNT, 0)
+                startForegroundService()
+            }
+            ACTION_STOP -> {
+                stopForegroundService()
+            }
+            ACTION_UPDATE_PROGRESS -> {
+                currentTrackName = intent.getStringExtra(EXTRA_TRACK_NAME) ?: currentTrackName
+                currentArtistName = intent.getStringExtra(EXTRA_ARTIST_NAME) ?: currentArtistName
+                val progress = intent.getLongExtra(EXTRA_PROGRESS, 0)
+                val total = intent.getLongExtra(EXTRA_TOTAL, 0)
+                queueCount = intent.getIntExtra(EXTRA_QUEUE_COUNT, queueCount)
+                updateNotification(progress, total)
+            }
         }
-        return START_NOT_STICKY
+        return START_STICKY
     }
-
+    
     override fun onBind(intent: Intent?): IBinder? = null
-
+    
+    /**
+     * Called when the foreground service timeout is reached (Android 15+, API 35+).
+     * dataSync services have a 6-hour limit in a 24-hour period.
+     * We must call stopSelf() within a few seconds to avoid a crash.
+     */
+    override fun onTimeout(startId: Int, fgsType: Int) {
+        // Log the timeout for debugging
+        android.util.Log.w("DownloadService", "Foreground service timeout reached (6 hours limit). Stopping service.")
+        
+        // Gracefully stop the service
+        stopForegroundService()
+    }
+    
     private fun createNotificationChannel() {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
             val channel = NotificationChannel(
                 CHANNEL_ID,
-                "Download Progress",
+                "Download Service",
                 NotificationManager.IMPORTANCE_LOW
             ).apply {
-                description = "Shows download progress for SpotiFLAC"
+                description = "Shows download progress"
                 setShowBadge(false)
             }
             val manager = getSystemService(NotificationManager::class.java)
             manager.createNotificationChannel(channel)
         }
     }
-
+    
     private fun startForegroundService() {
-        val notification = createNotification("Downloading...", 0)
+        isRunning = true
+        
+        // Acquire wake lock to prevent CPU sleep
+        val powerManager = getSystemService(Context.POWER_SERVICE) as PowerManager
+        wakeLock = powerManager.newWakeLock(
+            PowerManager.PARTIAL_WAKE_LOCK,
+            WAKELOCK_TAG
+        ).apply {
+            acquire(60 * 60 * 1000L) // 1 hour max
+        }
+        
+        val notification = buildNotification(0, 0)
         startForeground(NOTIFICATION_ID, notification)
     }
-
-    fun updateProgress(trackName: String, progress: Int) {
-        val notification = createNotification(trackName, progress)
+    
+    private fun stopForegroundService() {
+        isRunning = false
+        wakeLock?.let {
+            if (it.isHeld) {
+                it.release()
+            }
+        }
+        wakeLock = null
+        stopForeground(STOP_FOREGROUND_REMOVE)
+        stopSelf()
+    }
+    
+    private fun updateNotification(progress: Long, total: Long) {
+        if (!isRunning) return
+        
+        val notification = buildNotification(progress, total)
         val manager = getSystemService(NotificationManager::class.java)
         manager.notify(NOTIFICATION_ID, notification)
     }
-
-    private fun createNotification(title: String, progress: Int): Notification {
-        val intent = Intent(this, MainActivity::class.java)
+    
+    private fun buildNotification(progress: Long, total: Long): Notification {
         val pendingIntent = PendingIntent.getActivity(
-            this, 0, intent,
+            this,
+            0,
+            Intent(this, MainActivity::class.java),
             PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
         )
-
-        val stopIntent = Intent(this, DownloadService::class.java).apply {
-            action = ACTION_STOP
+        
+        val title = if (queueCount > 1) {
+            "Downloading $queueCount tracks"
+        } else if (currentTrackName.isNotEmpty()) {
+            currentTrackName
+        } else {
+            "Downloading..."
         }
-        val stopPendingIntent = PendingIntent.getService(
-            this, 0, stopIntent,
-            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
-        )
-
-        return NotificationCompat.Builder(this, CHANNEL_ID)
-            .setContentTitle("SpotiFLAC")
-            .setContentText(title)
+        
+        val text = if (currentArtistName.isNotEmpty() && queueCount <= 1) {
+            currentArtistName
+        } else if (total > 0) {
+            val progressPercent = (progress * 100 / total).toInt()
+            val progressMB = progress / (1024.0 * 1024.0)
+            val totalMB = total / (1024.0 * 1024.0)
+            String.format("%.1f / %.1f MB (%d%%)", progressMB, totalMB, progressPercent)
+        } else {
+            "Preparing download..."
+        }
+        
+        val builder = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(title)
+            .setContentText(text)
             .setSmallIcon(android.R.drawable.stat_sys_download)
-            .setProgress(100, progress, progress == 0)
-            .setOngoing(true)
             .setContentIntent(pendingIntent)
-            .addAction(android.R.drawable.ic_menu_close_clear_cancel, "Cancel", stopPendingIntent)
-            .build()
+            .setOngoing(true)
+            .setOnlyAlertOnce(true)
+            .setPriority(NotificationCompat.PRIORITY_LOW)
+            .setCategory(NotificationCompat.CATEGORY_PROGRESS)
+        
+        if (total > 0) {
+            builder.setProgress(100, (progress * 100 / total).toInt(), false)
+        } else {
+            builder.setProgress(0, 0, true)
+        }
+        
+        return builder.build()
+    }
+    
+    override fun onDestroy() {
+        isRunning = false
+        wakeLock?.let {
+            if (it.isHeld) {
+                it.release()
+            }
+        }
+        super.onDestroy()
     }
 }

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

@@ -1,9 +1,12 @@
 package com.zarz.spotiflac
 
+import android.content.Intent
 import io.flutter.embedding.android.FlutterActivity
 import io.flutter.embedding.engine.FlutterEngine
 import io.flutter.plugin.common.MethodChannel
 import gobackend.Gobackend
+import com.arthenica.ffmpegkit.FFmpegKit
+import com.arthenica.ffmpegkit.ReturnCode
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.SupervisorJob
@@ -12,8 +15,15 @@ import kotlinx.coroutines.withContext
 
 class MainActivity: FlutterActivity() {
     private val CHANNEL = "com.zarz.spotiflac/backend"
+    private val FFMPEG_CHANNEL = "com.zarz.spotiflac/ffmpeg"
     private val scope = CoroutineScope(SupervisorJob() + Dispatchers.Main)
 
+    override fun onNewIntent(intent: Intent) {
+        super.onNewIntent(intent)
+        // Update the intent so receive_sharing_intent can access the new data
+        setIntent(intent)
+    }
+
     override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
         super.configureFlutterEngine(flutterEngine)
         
@@ -43,6 +53,15 @@ class MainActivity: FlutterActivity() {
                             }
                             result.success(response)
                         }
+                        "searchSpotifyAll" -> {
+                            val query = call.argument<String>("query") ?: ""
+                            val trackLimit = call.argument<Int>("track_limit") ?: 15
+                            val artistLimit = call.argument<Int>("artist_limit") ?: 3
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.searchSpotifyAll(query, trackLimit.toLong(), artistLimit.toLong())
+                            }
+                            result.success(response)
+                        }
                         "checkAvailability" -> {
                             val spotifyId = call.argument<String>("spotify_id") ?: ""
                             val isrc = call.argument<String>("isrc") ?: ""
@@ -141,8 +160,9 @@ class MainActivity: FlutterActivity() {
                             val spotifyId = call.argument<String>("spotify_id") ?: ""
                             val trackName = call.argument<String>("track_name") ?: ""
                             val artistName = call.argument<String>("artist_name") ?: ""
+                            val filePath = call.argument<String>("file_path") ?: ""
                             val response = withContext(Dispatchers.IO) {
-                                Gobackend.getLyricsLRC(spotifyId, trackName, artistName)
+                                Gobackend.getLyricsLRC(spotifyId, trackName, artistName, filePath)
                             }
                             result.success(response)
                         }
@@ -160,6 +180,392 @@ class MainActivity: FlutterActivity() {
                             }
                             result.success(null)
                         }
+                        "readFileMetadata" -> {
+                            val filePath = call.argument<String>("file_path") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.readFileMetadata(filePath)
+                            }
+                            result.success(response)
+                        }
+                        "startDownloadService" -> {
+                            val trackName = call.argument<String>("track_name") ?: ""
+                            val artistName = call.argument<String>("artist_name") ?: ""
+                            val queueCount = call.argument<Int>("queue_count") ?: 0
+                            DownloadService.start(this@MainActivity, trackName, artistName, queueCount)
+                            result.success(null)
+                        }
+                        "stopDownloadService" -> {
+                            DownloadService.stop(this@MainActivity)
+                            result.success(null)
+                        }
+                        "updateDownloadServiceProgress" -> {
+                            val trackName = call.argument<String>("track_name") ?: ""
+                            val artistName = call.argument<String>("artist_name") ?: ""
+                            val progress = call.argument<Long>("progress") ?: 0L
+                            val total = call.argument<Long>("total") ?: 0L
+                            val queueCount = call.argument<Int>("queue_count") ?: 0
+                            DownloadService.updateProgress(this@MainActivity, trackName, artistName, progress, total, queueCount)
+                            result.success(null)
+                        }
+                        "isDownloadServiceRunning" -> {
+                            result.success(DownloadService.isServiceRunning())
+                        }
+                        "setSpotifyCredentials" -> {
+                            val clientId = call.argument<String>("client_id") ?: ""
+                            val clientSecret = call.argument<String>("client_secret") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setSpotifyAPICredentials(clientId, clientSecret)
+                            }
+                            result.success(null)
+                        }
+                        "hasSpotifyCredentials" -> {
+                            val hasCredentials = withContext(Dispatchers.IO) {
+                                Gobackend.checkSpotifyCredentials()
+                            }
+                            result.success(hasCredentials)
+                        }
+                        "preWarmTrackCache" -> {
+                            val tracksJson = call.argument<String>("tracks") ?: "[]"
+                            withContext(Dispatchers.IO) {
+                                Gobackend.preWarmTrackCacheJSON(tracksJson)
+                            }
+                            result.success(null)
+                        }
+                        "getTrackCacheSize" -> {
+                            val size = withContext(Dispatchers.IO) {
+                                Gobackend.getTrackCacheSize()
+                            }
+                            result.success(size.toInt())
+                        }
+                        "clearTrackCache" -> {
+                            withContext(Dispatchers.IO) {
+                                Gobackend.clearTrackIDCache()
+                            }
+                            result.success(null)
+                        }
+                        // Deezer API methods
+                        "searchDeezerAll" -> {
+                            val query = call.argument<String>("query") ?: ""
+                            val trackLimit = call.argument<Int>("track_limit") ?: 15
+                            val artistLimit = call.argument<Int>("artist_limit") ?: 3
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.searchDeezerAll(query, trackLimit.toLong(), artistLimit.toLong())
+                            }
+                            result.success(response)
+                        }
+                        "getDeezerMetadata" -> {
+                            val resourceType = call.argument<String>("resource_type") ?: ""
+                            val resourceId = call.argument<String>("resource_id") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getDeezerMetadata(resourceType, resourceId)
+                            }
+                            result.success(response)
+                        }
+                        "parseDeezerUrl" -> {
+                            val url = call.argument<String>("url") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.parseDeezerURLExport(url)
+                            }
+                            result.success(response)
+                        }
+                        "searchDeezerByISRC" -> {
+                            val isrc = call.argument<String>("isrc") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.searchDeezerByISRC(isrc)
+                            }
+                            result.success(response)
+                        }
+                        "convertSpotifyToDeezer" -> {
+                            val resourceType = call.argument<String>("resource_type") ?: ""
+                            val spotifyId = call.argument<String>("spotify_id") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.convertSpotifyToDeezer(resourceType, spotifyId)
+                            }
+                            result.success(response)
+                        }
+                        "getSpotifyMetadataWithFallback" -> {
+                            val url = call.argument<String>("url") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getSpotifyMetadataWithDeezerFallback(url)
+                            }
+                            result.success(response)
+                        }
+                        // Log methods
+                        "getLogs" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getLogs()
+                            }
+                            result.success(response)
+                        }
+                        "getLogsSince" -> {
+                            val index = call.argument<Int>("index") ?: 0
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getLogsSince(index.toLong())
+                            }
+                            result.success(response)
+                        }
+                        "clearLogs" -> {
+                            withContext(Dispatchers.IO) {
+                                Gobackend.clearLogs()
+                            }
+                            result.success(null)
+                        }
+                        "getLogCount" -> {
+                            val count = withContext(Dispatchers.IO) {
+                                Gobackend.getLogCount()
+                            }
+                            result.success(count.toInt())
+                        }
+                        "setLoggingEnabled" -> {
+                            val enabled = call.argument<Boolean>("enabled") ?: false
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setLoggingEnabled(enabled)
+                            }
+                            result.success(null)
+                        }
+                        // Extension System methods
+                        "initExtensionSystem" -> {
+                            val extensionsDir = call.argument<String>("extensions_dir") ?: ""
+                            val dataDir = call.argument<String>("data_dir") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.initExtensionSystem(extensionsDir, dataDir)
+                            }
+                            result.success(null)
+                        }
+                        "loadExtensionsFromDir" -> {
+                            val dirPath = call.argument<String>("dir_path") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.loadExtensionsFromDir(dirPath)
+                            }
+                            result.success(response)
+                        }
+                        "loadExtensionFromPath" -> {
+                            val filePath = call.argument<String>("file_path") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.loadExtensionFromPath(filePath)
+                            }
+                            result.success(response)
+                        }
+                        "unloadExtension" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.unloadExtensionByID(extensionId)
+                            }
+                            result.success(null)
+                        }
+                        "removeExtension" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.removeExtensionByID(extensionId)
+                            }
+                            result.success(null)
+                        }
+                        "upgradeExtension" -> {
+                            val filePath = call.argument<String>("file_path") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.upgradeExtensionFromPath(filePath)
+                            }
+                            result.success(response)
+                        }
+                        "checkExtensionUpgrade" -> {
+                            val filePath = call.argument<String>("file_path") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.checkExtensionUpgradeFromPath(filePath)
+                            }
+                            result.success(response)
+                        }
+                        "getInstalledExtensions" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getInstalledExtensions()
+                            }
+                            result.success(response)
+                        }
+                        "setExtensionEnabled" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val enabled = call.argument<Boolean>("enabled") ?: false
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setExtensionEnabledByID(extensionId, enabled)
+                            }
+                            result.success(null)
+                        }
+                        "setProviderPriority" -> {
+                            val priorityJson = call.argument<String>("priority") ?: "[]"
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setProviderPriorityJSON(priorityJson)
+                            }
+                            result.success(null)
+                        }
+                        "getProviderPriority" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getProviderPriorityJSON()
+                            }
+                            result.success(response)
+                        }
+                        "setMetadataProviderPriority" -> {
+                            val priorityJson = call.argument<String>("priority") ?: "[]"
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setMetadataProviderPriorityJSON(priorityJson)
+                            }
+                            result.success(null)
+                        }
+                        "getMetadataProviderPriority" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getMetadataProviderPriorityJSON()
+                            }
+                            result.success(response)
+                        }
+                        "getExtensionSettings" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getExtensionSettingsJSON(extensionId)
+                            }
+                            result.success(response)
+                        }
+                        "setExtensionSettings" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val settingsJson = call.argument<String>("settings") ?: "{}"
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setExtensionSettingsJSON(extensionId, settingsJson)
+                            }
+                            result.success(null)
+                        }
+                        "searchTracksWithExtensions" -> {
+                            val query = call.argument<String>("query") ?: ""
+                            val limit = call.argument<Int>("limit") ?: 20
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.searchTracksWithExtensionsJSON(query, limit.toLong())
+                            }
+                            result.success(response)
+                        }
+                        "downloadWithExtensions" -> {
+                            val requestJson = call.arguments as String
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.downloadWithExtensionsJSON(requestJson)
+                            }
+                            result.success(response)
+                        }
+                        "removeExtension" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.removeExtensionByID(extensionId)
+                            }
+                            result.success(null)
+                        }
+                        "cleanupExtensions" -> {
+                            withContext(Dispatchers.IO) {
+                                Gobackend.cleanupExtensions()
+                            }
+                            result.success(null)
+                        }
+                        // Extension Auth API methods
+                        "getExtensionPendingAuth" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getExtensionPendingAuthJSON(extensionId)
+                            }
+                            if (response.isNullOrEmpty()) {
+                                result.success(null)
+                            } else {
+                                result.success(response)
+                            }
+                        }
+                        "setExtensionAuthCode" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val authCode = call.argument<String>("auth_code") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setExtensionAuthCodeByID(extensionId, authCode)
+                            }
+                            result.success(null)
+                        }
+                        "setExtensionTokens" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val accessToken = call.argument<String>("access_token") ?: ""
+                            val refreshToken = call.argument<String>("refresh_token") ?: ""
+                            val expiresIn = call.argument<Int>("expires_in") ?: 0
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setExtensionTokensByID(extensionId, accessToken, refreshToken, expiresIn.toLong())
+                            }
+                            result.success(null)
+                        }
+                        "clearExtensionPendingAuth" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.clearExtensionPendingAuthByID(extensionId)
+                            }
+                            result.success(null)
+                        }
+                        "isExtensionAuthenticated" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val isAuth = withContext(Dispatchers.IO) {
+                                Gobackend.isExtensionAuthenticatedByID(extensionId)
+                            }
+                            result.success(isAuth)
+                        }
+                        "getAllPendingAuthRequests" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getAllPendingAuthRequestsJSON()
+                            }
+                            result.success(response)
+                        }
+                        // Extension FFmpeg API
+                        "getPendingFFmpegCommand" -> {
+                            val commandId = call.argument<String>("command_id") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getPendingFFmpegCommandJSON(commandId)
+                            }
+                            if (response.isNullOrEmpty()) {
+                                result.success(null)
+                            } else {
+                                result.success(response)
+                            }
+                        }
+                        "setFFmpegCommandResult" -> {
+                            val commandId = call.argument<String>("command_id") ?: ""
+                            val success = call.argument<Boolean>("success") ?: false
+                            val output = call.argument<String>("output") ?: ""
+                            val error = call.argument<String>("error") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setFFmpegCommandResultByID(commandId, success, output, error)
+                            }
+                            result.success(null)
+                        }
+                        "getAllPendingFFmpegCommands" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getAllPendingFFmpegCommandsJSON()
+                            }
+                            result.success(response)
+                        }
+                        // Extension Custom Search API
+                        "customSearchWithExtension" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val query = call.argument<String>("query") ?: ""
+                            val optionsJson = call.argument<String>("options") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.customSearchWithExtensionJSON(extensionId, query, optionsJson)
+                            }
+                            result.success(response)
+                        }
+                        "getSearchProviders" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getSearchProvidersJSON()
+                            }
+                            result.success(response)
+                        }
+                        // Extension Post-Processing API
+                        "runPostProcessing" -> {
+                            val filePath = call.argument<String>("file_path") ?: ""
+                            val metadataJson = call.argument<String>("metadata") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.runPostProcessingJSON(filePath, metadataJson)
+                            }
+                            result.success(response)
+                        }
+                        "getPostProcessingProviders" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getPostProcessingProvidersJSON()
+                            }
+                            result.success(response)
+                        }
                         else -> result.notImplemented()
                     }
                 } catch (e: Exception) {
@@ -167,5 +573,37 @@ class MainActivity: FlutterActivity() {
                 }
             }
         }
+        
+        // FFmpeg method channel
+        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, FFMPEG_CHANNEL).setMethodCallHandler { call, result ->
+            scope.launch {
+                try {
+                    when (call.method) {
+                        "execute" -> {
+                            val command = call.argument<String>("command") ?: ""
+                            val session = withContext(Dispatchers.IO) {
+                                FFmpegKit.execute(command)
+                            }
+                            val returnCode = session.returnCode
+                            val output = session.output ?: ""
+                            result.success(mapOf(
+                                "success" to ReturnCode.isSuccess(returnCode),
+                                "returnCode" to (returnCode?.value ?: -1),
+                                "output" to output
+                            ))
+                        }
+                        "getVersion" -> {
+                            val session = withContext(Dispatchers.IO) {
+                                FFmpegKit.execute("-version")
+                            }
+                            result.success(session.output ?: "unknown")
+                        }
+                        else -> result.notImplemented()
+                    }
+                } catch (e: Exception) {
+                    result.error("FFMPEG_ERROR", e.message, null)
+                }
+            }
+        }
     }
 }

android/settings.gradle.kts

@@ -20,7 +20,7 @@ pluginManagement {
 plugins {
     id("dev.flutter.flutter-plugin-loader") version "1.0.0"
     id("com.android.application") version "8.11.1" apply false
-    id("org.jetbrains.kotlin.android") version "2.2.20" apply false
+    id("org.jetbrains.kotlin.android") version "2.3.0" apply false
 }
 
 include(":app")

build_assets/ffmpeg_service_ios.dart

@@ -0,0 +1,208 @@
+import 'dart:io';
+import 'package:ffmpeg_kit_flutter_new_audio/ffmpeg_kit.dart';
+import 'package:ffmpeg_kit_flutter_new_audio/return_code.dart';
+import 'package:spotiflac_android/utils/logger.dart';
+
+final _log = AppLogger('FFmpeg');
+
+/// FFmpeg service for iOS using ffmpeg_kit_flutter plugin
+class FFmpegServiceIOS {
+  /// Execute FFmpeg command and return result
+  static Future<FFmpegResultIOS> _execute(String command) async {
+    try {
+      final session = await FFmpegKit.execute(command);
+      final returnCode = await session.getReturnCode();
+      final output = await session.getOutput() ?? '';
+      return FFmpegResultIOS(
+        success: ReturnCode.isSuccess(returnCode),
+        returnCode: returnCode?.getValue() ?? -1,
+        output: output,
+      );
+    } catch (e) {
+      _log.e('FFmpeg execute error: $e');
+      return FFmpegResultIOS(success: false, returnCode: -1, output: e.toString());
+    }
+  }
+
+  /// Convert M4A (DASH segments) to FLAC
+  static Future<String?> convertM4aToFlac(String inputPath) async {
+    final outputPath = inputPath.replaceAll('.m4a', '.flac');
+    final command = '-i "$inputPath" -c:a flac -compression_level 8 "$outputPath" -y';
+    final result = await _execute(command);
+
+    if (result.success) {
+      try {
+        await File(inputPath).delete();
+      } catch (_) {}
+      return outputPath;
+    }
+
+    _log.e('M4A to FLAC conversion failed: ${result.output}');
+    return null;
+  }
+
+  /// Convert FLAC to MP3
+  static Future<String?> convertFlacToMp3(String inputPath, {String bitrate = '320k'}) async {
+    final dir = File(inputPath).parent.path;
+    final baseName = inputPath.split(Platform.pathSeparator).last.replaceAll('.flac', '');
+    final outputDir = '$dir${Platform.pathSeparator}MP3';
+    await Directory(outputDir).create(recursive: true);
+    final outputPath = '$outputDir${Platform.pathSeparator}$baseName.mp3';
+
+    final command = '-i "$inputPath" -codec:a libmp3lame -b:a $bitrate -map 0:a -map_metadata 0 -id3v2_version 3 "$outputPath" -y';
+    final result = await _execute(command);
+
+    if (result.success) return outputPath;
+    _log.e('FLAC to MP3 conversion failed: ${result.output}');
+    return null;
+  }
+
+  /// Convert FLAC to M4A
+  static Future<String?> convertFlacToM4a(String inputPath, {String codec = 'aac', String bitrate = '256k'}) async {
+    final dir = File(inputPath).parent.path;
+    final baseName = inputPath.split(Platform.pathSeparator).last.replaceAll('.flac', '');
+    final outputDir = '$dir${Platform.pathSeparator}M4A';
+    await Directory(outputDir).create(recursive: true);
+    final outputPath = '$outputDir${Platform.pathSeparator}$baseName.m4a';
+
+    String command;
+    if (codec == 'alac') {
+      command = '-i "$inputPath" -codec:a alac -map 0:a -map_metadata 0 "$outputPath" -y';
+    } else {
+      command = '-i "$inputPath" -codec:a aac -b:a $bitrate -map 0:a -map_metadata 0 "$outputPath" -y';
+    }
+
+    final result = await _execute(command);
+    if (result.success) return outputPath;
+    _log.e('FLAC to M4A conversion failed: ${result.output}');
+    return null;
+  }
+
+  /// Embed cover art to FLAC file
+  static Future<String?> embedCover(String flacPath, String coverPath) async {
+    final tempOutput = '$flacPath.tmp';
+    final command = '-i "$flacPath" -i "$coverPath" -map 0:a -map 1:0 -c copy -metadata:s:v title="Album cover" -metadata:s:v comment="Cover (front)" -disposition:v attached_pic "$tempOutput" -y';
+
+    final result = await _execute(command);
+
+    if (result.success) {
+      try {
+        await File(flacPath).delete();
+        await File(tempOutput).rename(flacPath);
+        return flacPath;
+      } catch (e) {
+        _log.e('Failed to replace file after cover embed: $e');
+        return null;
+      }
+    }
+
+    try {
+      final tempFile = File(tempOutput);
+      if (await tempFile.exists()) await tempFile.delete();
+    } catch (_) {}
+
+    _log.e('Cover embed failed: ${result.output}');
+    return null;
+  }
+
+  /// Embed metadata and cover art to FLAC file
+  /// Returns the file path on success, null on failure
+  static Future<String?> embedMetadata({
+    required String flacPath,
+    String? coverPath,
+    Map<String, String>? metadata,
+  }) async {
+    final tempOutput = '$flacPath.tmp';
+    
+    // Construct command
+    final StringBuffer cmdBuffer = StringBuffer();
+    cmdBuffer.write('-i "$flacPath" ');
+    
+    // Add cover input if available
+    if (coverPath != null) {
+      cmdBuffer.write('-i "$coverPath" ');
+    }
+    
+    // Map audio stream
+    cmdBuffer.write('-map 0:a ');
+    
+    // Map cover stream if available
+    if (coverPath != null) {
+      cmdBuffer.write('-map 1:0 ');
+      cmdBuffer.write('-c:v copy ');
+      cmdBuffer.write('-disposition:v attached_pic ');
+      cmdBuffer.write('-metadata:s:v title="Album cover" ');
+      cmdBuffer.write('-metadata:s:v comment="Cover (front)" ');
+    }
+    
+    // Copy audio codec (don't re-encode)
+    cmdBuffer.write('-c:a copy ');
+    
+    // Add text metadata
+    if (metadata != null) {
+      metadata.forEach((key, value) {
+        // Sanitize value: escape double quotes
+        final sanitizedValue = value.replaceAll('"', '\\"');
+        cmdBuffer.write('-metadata $key="$sanitizedValue" ');
+      });
+    }
+    
+    cmdBuffer.write('"$tempOutput" -y');
+    
+    final command = cmdBuffer.toString();
+    _log.d('Executing FFmpeg command: $command');
+
+    final result = await _execute(command);
+
+    if (result.success) {
+      try {
+        await File(flacPath).delete();
+        await File(tempOutput).rename(flacPath);
+        return flacPath;
+      } catch (e) {
+        _log.e('Failed to replace file after metadata embed: $e');
+        return null;
+      }
+    }
+
+    // Clean up temp file if exists
+    try {
+      final tempFile = File(tempOutput);
+      if (await tempFile.exists()) {
+        await tempFile.delete();
+      }
+    } catch (_) {}
+
+    _log.e('Metadata/Cover embed failed: ${result.output}');
+    return null;
+  }
+
+  /// Check if FFmpeg is available
+  static Future<bool> isAvailable() async {
+    try {
+      final session = await FFmpegKit.execute('-version');
+      final returnCode = await session.getReturnCode();
+      return ReturnCode.isSuccess(returnCode);
+    } catch (e) {
+      return false;
+    }
+  }
+
+  /// Get FFmpeg version info
+  static Future<String?> getVersion() async {
+    try {
+      final session = await FFmpegKit.execute('-version');
+      return await session.getOutput();
+    } catch (e) {
+      return null;
+    }
+  }
+}
+
+class FFmpegResultIOS {
+  final bool success;
+  final int returnCode;
+  final String output;
+
+  FFmpegResultIOS({required this.success, required this.returnCode, required this.output});
+}

devtools_options.yaml

@@ -0,0 +1,3 @@
+description: This file stores settings for Dart & Flutter DevTools.
+documentation: https://docs.flutter.dev/tools/devtools/extensions#configure-extension-enablement-states
+extensions:

go_backend/amazon.go

@@ -1,6 +1,7 @@
 package gobackend
 
 import (
+	"bufio"
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
@@ -10,15 +11,26 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"time"
 )
 
 // AmazonDownloader handles Amazon Music downloads using DoubleDouble service (same as PC)
 type AmazonDownloader struct {
-	client  *http.Client
-	regions []string // us, eu regions for DoubleDouble service
+	client           *http.Client
+	regions          []string  // us, eu regions for DoubleDouble service
+	lastAPICallTime  time.Time // Rate limiting: track last API call
+	apiCallCount     int       // Rate limiting: counter per minute
+	apiCallResetTime time.Time // Rate limiting: reset time
 }
 
+var (
+	// Global Amazon downloader instance for connection reuse
+	globalAmazonDownloader *AmazonDownloader
+	amazonDownloaderOnce   sync.Once
+	amazonRateLimitMu      sync.Mutex // Mutex for rate limiting
+)
+
 // DoubleDoubleSubmitResponse is the response from DoubleDouble submit endpoint
 type DoubleDoubleSubmitResponse struct {
 	Success bool   `json:"success"`
@@ -36,12 +48,114 @@ type DoubleDoubleStatusResponse struct {
 	} `json:"current"`
 }
 
-// NewAmazonDownloader creates a new Amazon downloader using DoubleDouble service
-func NewAmazonDownloader() *AmazonDownloader {
-	return &AmazonDownloader{
-		client:  NewHTTPClientWithTimeout(120 * time.Second), // 120s timeout like PC
-		regions: []string{"us", "eu"},                        // Same regions as PC
+// amazonArtistsMatch checks if the artist names are similar enough
+func amazonArtistsMatch(expectedArtist, foundArtist string) bool {
+	normExpected := strings.ToLower(strings.TrimSpace(expectedArtist))
+	normFound := strings.ToLower(strings.TrimSpace(foundArtist))
+
+	// Exact match
+	if normExpected == normFound {
+		return true
 	}
+
+	// Check if one contains the other
+	if strings.Contains(normExpected, normFound) || strings.Contains(normFound, normExpected) {
+		return true
+	}
+
+	// Check first artist (before comma or feat)
+	expectedFirst := strings.Split(normExpected, ",")[0]
+	expectedFirst = strings.Split(expectedFirst, " feat")[0]
+	expectedFirst = strings.Split(expectedFirst, " ft.")[0]
+	expectedFirst = strings.TrimSpace(expectedFirst)
+
+	foundFirst := strings.Split(normFound, ",")[0]
+	foundFirst = strings.Split(foundFirst, " feat")[0]
+	foundFirst = strings.Split(foundFirst, " ft.")[0]
+	foundFirst = strings.TrimSpace(foundFirst)
+
+	if expectedFirst == foundFirst {
+		return true
+	}
+
+	// Check if first artist is contained in the other
+	if strings.Contains(expectedFirst, foundFirst) || strings.Contains(foundFirst, expectedFirst) {
+		return true
+	}
+
+	// If scripts are different (one is ASCII, one is non-ASCII like Japanese/Chinese/Korean),
+	// assume they're the same artist with different transliteration
+	expectedASCII := amazonIsASCIIString(expectedArtist)
+	foundASCII := amazonIsASCIIString(foundArtist)
+	if expectedASCII != foundASCII {
+		GoLog("[Amazon] Artist names in different scripts, assuming match: '%s' vs '%s'\n", expectedArtist, foundArtist)
+		return true
+	}
+
+	return false
+}
+
+// amazonIsASCIIString checks if a string contains only ASCII characters
+func amazonIsASCIIString(s string) bool {
+	for _, r := range s {
+		if r > 127 {
+			return false
+		}
+	}
+	return true
+}
+
+// NewAmazonDownloader creates a new Amazon downloader (returns singleton for connection reuse)
+func NewAmazonDownloader() *AmazonDownloader {
+	amazonDownloaderOnce.Do(func() {
+		globalAmazonDownloader = &AmazonDownloader{
+			client:           NewHTTPClientWithTimeout(120 * time.Second), // 120s timeout like PC
+			regions:          []string{"us", "eu"},                        // Same regions as PC
+			apiCallResetTime: time.Now(),
+		}
+	})
+	return globalAmazonDownloader
+}
+
+// waitForRateLimit implements rate limiting similar to PC version
+// Max 9 requests per minute with 7 second delay between requests
+func (a *AmazonDownloader) waitForRateLimit() {
+	amazonRateLimitMu.Lock()
+	defer amazonRateLimitMu.Unlock()
+
+	now := time.Now()
+
+	// Reset counter every minute
+	if now.Sub(a.apiCallResetTime) >= time.Minute {
+		a.apiCallCount = 0
+		a.apiCallResetTime = now
+	}
+
+	// If we've hit the limit (9 requests per minute), wait until next minute
+	if a.apiCallCount >= 9 {
+		waitTime := time.Minute - now.Sub(a.apiCallResetTime)
+		if waitTime > 0 {
+			GoLog("[Amazon] Rate limit reached, waiting %v...\n", waitTime.Round(time.Second))
+			time.Sleep(waitTime)
+			a.apiCallCount = 0
+			a.apiCallResetTime = time.Now()
+		}
+	}
+
+	// Add delay between requests (7 seconds like PC version)
+	if !a.lastAPICallTime.IsZero() {
+		timeSinceLastCall := now.Sub(a.lastAPICallTime)
+		minDelay := 7 * time.Second
+		if timeSinceLastCall < minDelay {
+			waitTime := minDelay - timeSinceLastCall
+			GoLog("[Amazon] Rate limiting: waiting %v...\n", waitTime.Round(time.Second))
+			time.Sleep(waitTime)
+		}
+	}
+
+	// Update tracking
+	a.lastAPICallTime = time.Now()
+	a.apiCallCount++
 }
 
 // GetAvailableAPIs returns list of available DoubleDouble regions
@@ -56,26 +170,28 @@ func (a *AmazonDownloader) GetAvailableAPIs() []string {
 	return apis
 }
 
-
 // downloadFromDoubleDoubleService downloads a track using DoubleDouble service (same as PC)
 // This uses submit → poll → download mechanism
 // Internal function - not exported to gomobile
-func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, outputDir string) (string, string, string, error) {
+func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, _ string) (string, string, string, error) {
 	var lastError error
 
 	for _, region := range a.regions {
-		fmt.Printf("[Amazon] Trying region: %s...\n", region)
+		GoLog("[Amazon] Trying region: %s...\n", region)
 
 		// Build base URL for DoubleDouble service
 		// Decode base64 service URL (same as PC)
-		serviceBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly8=")         // https://
+		serviceBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly8=")               // https://
 		serviceDomain, _ := base64.StdEncoding.DecodeString("LmRvdWJsZWRvdWJsZS50b3A=") // .doubledouble.top
 		baseURL := fmt.Sprintf("%s%s%s", string(serviceBase), region, string(serviceDomain))
 
-		// Step 1: Submit download request
+		// Step 1: Submit download request with rate limiting
 		encodedURL := url.QueryEscape(amazonURL)
 		submitURL := fmt.Sprintf("%s/dl?url=%s", baseURL, encodedURL)
 
+		// Apply rate limiting before request (like PC version)
+		a.waitForRateLimit()
+
 		req, err := http.NewRequest("GET", submitURL, nil)
 		if err != nil {
 			lastError = fmt.Errorf("failed to create request: %w", err)
@@ -85,15 +201,43 @@ func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, outputDir
 		req.Header.Set("User-Agent", getRandomUserAgent())
 
 		fmt.Println("[Amazon] Submitting download request...")
-		resp, err := a.client.Do(req)
-		if err != nil {
-			lastError = fmt.Errorf("failed to submit request: %w", err)
-			continue
+
+		// Retry logic for 429 errors (like PC version: 3 retries with 15s wait)
+		var resp *http.Response
+		maxRetries := 3
+		for retry := 0; retry < maxRetries; retry++ {
+			resp, err = a.client.Do(req)
+			if err != nil {
+				lastError = fmt.Errorf("failed to submit request: %w", err)
+				break
+			}
+
+			if resp.StatusCode == 429 { // Too Many Requests
+				resp.Body.Close()
+				if retry < maxRetries-1 {
+					waitTime := 15 * time.Second
+					GoLog("[Amazon] Rate limited (429), waiting %v before retry %d/%d...\n", waitTime, retry+2, maxRetries)
+					time.Sleep(waitTime)
+					continue
+				}
+				lastError = fmt.Errorf("API rate limit exceeded after %d retries", maxRetries)
+				break
+			}
+
+			if resp.StatusCode != 200 {
+				resp.Body.Close()
+				lastError = fmt.Errorf("submit failed with status %d", resp.StatusCode)
+				break
+			}
+
+			// Success - break retry loop
+			break
 		}
 
-		if resp.StatusCode != 200 {
-			resp.Body.Close()
-			lastError = fmt.Errorf("submit failed with status %d", resp.StatusCode)
+		if err != nil || lastError != nil {
+			if resp != nil {
+				resp.Body.Close()
+			}
 			continue
 		}
 
@@ -111,7 +255,7 @@ func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, outputDir
 		}
 
 		downloadID := submitResp.ID
-		fmt.Printf("[Amazon] Download ID: %s\n", downloadID)
+		GoLog("[Amazon] Download ID: %s\n", downloadID)
 
 		// Step 2: Poll for completion
 		statusURL := fmt.Sprintf("%s/dl/%s", baseURL, downloadID)
@@ -166,7 +310,7 @@ func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, outputDir
 				trackName := status.Current.Name
 				artist := status.Current.Artist
 
-				fmt.Printf("[Amazon] Downloading: %s - %s\n", artist, trackName)
+				GoLog("[Amazon] Downloading: %s - %s\n", artist, trackName)
 				return fileURL, trackName, artist, nil
 
 			} else if status.Status == "error" {
@@ -200,15 +344,9 @@ func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, outputDir
 	return "", "", "", fmt.Errorf("all regions failed. Last error: %v", lastError)
 }
 
-
 // DownloadFile downloads a file from URL with User-Agent and progress tracking
 func (a *AmazonDownloader) DownloadFile(downloadURL, outputPath, itemID string) error {
-	// Set current file being downloaded (legacy)
-	SetCurrentFile(filepath.Base(outputPath))
-	SetDownloading(true)
-	defer SetDownloading(false)
-
-	// Initialize item progress if itemID provided
+	// Initialize item progress (required for all downloads)
 	if itemID != "" {
 		StartItemProgress(itemID)
 		defer CompleteItemProgress(itemID)
@@ -231,71 +369,130 @@ func (a *AmazonDownloader) DownloadFile(downloadURL, outputPath, itemID string)
 		return fmt.Errorf("download failed: HTTP %d", resp.StatusCode)
 	}
 
+	expectedSize := resp.ContentLength
 	// Set total bytes if available
-	if resp.ContentLength > 0 {
-		SetBytesTotal(resp.ContentLength)
-		if itemID != "" {
-			SetItemBytesTotal(itemID, resp.ContentLength)
-		}
+	if expectedSize > 0 && itemID != "" {
+		SetItemBytesTotal(itemID, expectedSize)
 	}
 
 	out, err := os.Create(outputPath)
 	if err != nil {
 		return err
 	}
-	defer out.Close()
 
-	// Use appropriate progress writer
-	var bytesWritten int64
+	// Use buffered writer for better performance (256KB buffer)
+	bufWriter := bufio.NewWriterSize(out, 256*1024)
+
+	// Use item progress writer with buffered output
+	var written int64
 	if itemID != "" {
-		pw := NewItemProgressWriter(out, itemID)
-		bytesWritten, err = io.Copy(pw, resp.Body)
+		pw := NewItemProgressWriter(bufWriter, itemID)
+		written, err = io.Copy(pw, resp.Body)
 	} else {
-		pw := NewProgressWriter(out)
-		bytesWritten, err = io.Copy(pw, resp.Body)
-	}
-	if err != nil {
-		return fmt.Errorf("failed to write file: %w", err)
+		// Fallback: direct copy without progress tracking
+		written, err = io.Copy(bufWriter, resp.Body)
 	}
 
-	fmt.Printf("\r[Amazon] Downloaded: %.2f MB (Complete)\n", float64(bytesWritten)/(1024*1024))
+	// Flush buffer before checking for errors
+	flushErr := bufWriter.Flush()
+	closeErr := out.Close()
+
+	// Check for any errors
+	if err != nil {
+		os.Remove(outputPath)
+		return fmt.Errorf("download interrupted: %w", err)
+	}
+	if flushErr != nil {
+		os.Remove(outputPath)
+		return fmt.Errorf("failed to flush buffer: %w", flushErr)
+	}
+	if closeErr != nil {
+		os.Remove(outputPath)
+		return fmt.Errorf("failed to close file: %w", closeErr)
+	}
+
+	// Verify file size if Content-Length was provided
+	if expectedSize > 0 && written != expectedSize {
+		os.Remove(outputPath)
+		return fmt.Errorf("incomplete download: expected %d bytes, got %d bytes", expectedSize, written)
+	}
+
+	fmt.Printf("\r[Amazon] Downloaded: %.2f MB (Complete)\n", float64(written)/(1024*1024))
 	return nil
 }
 
+// AmazonDownloadResult contains download result with quality info
+type AmazonDownloadResult struct {
+	FilePath    string
+	BitDepth    int
+	SampleRate  int
+	Title       string
+	Artist      string
+	Album       string
+	ReleaseDate string
+	TrackNumber int
+	DiscNumber  int
+	ISRC        string
+}
+
 // downloadFromAmazon downloads a track using the request parameters
 // Uses DoubleDouble service (same as PC version)
-func downloadFromAmazon(req DownloadRequest) (string, error) {
+func downloadFromAmazon(req DownloadRequest) (AmazonDownloadResult, error) {
 	downloader := NewAmazonDownloader()
 
 	// Check for existing file first
 	if existingFile, exists := checkISRCExistsInternal(req.OutputDir, req.ISRC); exists {
-		return "EXISTS:" + existingFile, nil
+		return AmazonDownloadResult{FilePath: "EXISTS:" + existingFile}, nil
 	}
 
 	// Get Amazon URL from SongLink
 	songlink := NewSongLinkClient()
-	availability, err := songlink.CheckTrackAvailability(req.SpotifyID, req.ISRC)
+	var availability *TrackAvailability
+	var err error
+
+	// Check if SpotifyID is actually a Deezer ID (format: "deezer:xxxxx")
+	if strings.HasPrefix(req.SpotifyID, "deezer:") {
+		// Extract Deezer ID and use Deezer-based lookup
+		deezerID := strings.TrimPrefix(req.SpotifyID, "deezer:")
+		GoLog("[Amazon] Using Deezer ID for SongLink lookup: %s\n", deezerID)
+		availability, err = songlink.CheckAvailabilityFromDeezer(deezerID)
+	} else if req.SpotifyID != "" {
+		// Use Spotify ID
+		availability, err = songlink.CheckTrackAvailability(req.SpotifyID, req.ISRC)
+	} else {
+		return AmazonDownloadResult{}, fmt.Errorf("no valid Spotify or Deezer ID provided for Amazon lookup")
+	}
+
 	if err != nil {
-		return "", fmt.Errorf("failed to check Amazon availability via SongLink: %w", err)
+		return AmazonDownloadResult{}, fmt.Errorf("failed to check Amazon availability via SongLink: %w", err)
 	}
 
 	if !availability.Amazon || availability.AmazonURL == "" {
-		return "", fmt.Errorf("track not available on Amazon Music (SongLink returned no Amazon URL)")
+		return AmazonDownloadResult{}, fmt.Errorf("track not available on Amazon Music (SongLink returned no Amazon URL)")
 	}
 
 	// Create output directory if needed
 	if req.OutputDir != "." {
 		if err := os.MkdirAll(req.OutputDir, 0755); err != nil {
-			return "", fmt.Errorf("failed to create output directory: %w", err)
+			return AmazonDownloadResult{}, fmt.Errorf("failed to create output directory: %w", err)
 		}
 	}
 
 	// Download using DoubleDouble service (same as PC)
 	downloadURL, trackName, artistName, err := downloader.downloadFromDoubleDoubleService(availability.AmazonURL, req.OutputDir)
 	if err != nil {
-		return "", fmt.Errorf("failed to get download URL: %w", err)
+		return AmazonDownloadResult{}, fmt.Errorf("failed to get download URL: %w", err)
 	}
 
+	// Verify artist matches
+	if artistName != "" && !amazonArtistsMatch(req.ArtistName, artistName) {
+		GoLog("[Amazon] Artist mismatch: expected '%s', got '%s'. Rejecting.\n", req.ArtistName, artistName)
+		return AmazonDownloadResult{}, fmt.Errorf("artist mismatch: expected '%s', got '%s'", req.ArtistName, artistName)
+	}
+
+	// Log match found
+	GoLog("[Amazon] Match found: '%s' by '%s'\n", trackName, artistName)
+
 	// Build filename using Spotify metadata (more accurate)
 	filename := buildFilenameFromTemplate(req.FilenameFormat, map[string]interface{}{
 		"title":  req.TrackName,
@@ -310,80 +507,144 @@ func downloadFromAmazon(req DownloadRequest) (string, error) {
 
 	// Check if file already exists
 	if fileInfo, statErr := os.Stat(outputPath); statErr == nil && fileInfo.Size() > 0 {
-		return "EXISTS:" + outputPath, nil
+		return AmazonDownloadResult{FilePath: "EXISTS:" + outputPath}, nil
 	}
 
-	// Download file with item ID for progress tracking
+	// START PARALLEL: Fetch cover and lyrics while downloading audio
+	var parallelResult *ParallelDownloadResult
+	parallelDone := make(chan struct{})
+	go func() {
+		defer close(parallelDone)
+		parallelResult = FetchCoverAndLyricsParallel(
+			req.CoverURL,
+			req.EmbedMaxQualityCover,
+			req.SpotifyID,
+			req.TrackName,
+			req.ArtistName,
+			req.EmbedLyrics,
+		)
+	}()
+
+	// Download audio file with item ID for progress tracking
 	if err := downloader.DownloadFile(downloadURL, outputPath, req.ItemID); err != nil {
-		return "", fmt.Errorf("download failed: %w", err)
+		return AmazonDownloadResult{}, fmt.Errorf("download failed: %w", err)
+	}
+
+	// Wait for parallel operations to complete
+	<-parallelDone
+
+	// Set progress to 100% and status to finalizing (before embedding)
+	// This makes the UI show "Finalizing..." while embedding happens
+	if req.ItemID != "" {
+		SetItemProgress(req.ItemID, 1.0, 0, 0)
+		SetItemFinalizing(req.ItemID)
 	}
 
 	// Log track info from DoubleDouble (for debugging)
 	if trackName != "" && artistName != "" {
-		fmt.Printf("[Amazon] DoubleDouble returned: %s - %s\n", artistName, trackName)
+		GoLog("[Amazon] DoubleDouble returned: %s - %s\n", artistName, trackName)
+	}
+
+	// Read existing metadata from downloaded file BEFORE embedding
+	// Amazon/DoubleDouble files often have correct track/disc numbers that we should preserve
+	existingMeta, metaErr := ReadMetadata(outputPath)
+	actualTrackNum := req.TrackNumber
+	actualDiscNum := req.DiscNumber
+
+	if metaErr == nil && existingMeta != nil {
+		// Use file metadata if it has valid track/disc numbers and request doesn't have them
+		if existingMeta.TrackNumber > 0 && (req.TrackNumber == 0 || req.TrackNumber == 1) {
+			actualTrackNum = existingMeta.TrackNumber
+			GoLog("[Amazon] Using track number from file: %d (request had: %d)\n", actualTrackNum, req.TrackNumber)
+		}
+		if existingMeta.DiscNumber > 0 && (req.DiscNumber == 0 || req.DiscNumber == 1) {
+			actualDiscNum = existingMeta.DiscNumber
+			GoLog("[Amazon] Using disc number from file: %d (request had: %d)\n", actualDiscNum, req.DiscNumber)
+		}
 	}
 
 	// Embed metadata using Spotify data (more accurate than DoubleDouble)
+	// But preserve track/disc numbers from file if they were better
 	metadata := Metadata{
 		Title:       req.TrackName,
 		Artist:      req.ArtistName,
 		Album:       req.AlbumName,
 		AlbumArtist: req.AlbumArtist,
 		Date:        req.ReleaseDate,
-		TrackNumber: req.TrackNumber,
+		TrackNumber: actualTrackNum,
 		TotalTracks: req.TotalTracks,
-		DiscNumber:  req.DiscNumber,
+		DiscNumber:  actualDiscNum,
 		ISRC:        req.ISRC,
 	}
 
-	// Download cover to memory (avoids file permission issues on Android)
+	// Use cover data from parallel fetch
 	var coverData []byte
-	if req.CoverURL != "" {
-		fmt.Println("[Amazon] Downloading cover to memory...")
-		data, err := downloadCoverToMemory(req.CoverURL, req.EmbedMaxQualityCover)
-		if err == nil {
-			coverData = data
-			fmt.Printf("[Amazon] Cover downloaded successfully (%d bytes)\n", len(coverData))
-		} else {
-			fmt.Printf("[Amazon] Warning: failed to download cover: %v\n", err)
-		}
+	if parallelResult != nil && parallelResult.CoverData != nil {
+		coverData = parallelResult.CoverData
+		GoLog("[Amazon] Using parallel-fetched cover (%d bytes)\n", len(coverData))
 	}
 
 	if err := EmbedMetadataWithCoverData(outputPath, metadata, coverData); err != nil {
 		fmt.Printf("Warning: failed to embed metadata: %v\n", err)
 	}
 
-	// Embed lyrics if enabled
-	if req.EmbedLyrics {
-		fmt.Println("[Amazon] Fetching lyrics...")
-		lyricsClient := NewLyricsClient()
-		lyrics, lyricsErr := lyricsClient.FetchLyricsAllSources(req.SpotifyID, req.TrackName, req.ArtistName)
-		if lyricsErr != nil {
-			fmt.Printf("[Amazon] Warning: lyrics fetch error: %v\n", lyricsErr)
-		} else if lyrics == nil || len(lyrics.Lines) == 0 {
-			fmt.Println("[Amazon] No lyrics found for this track")
+	// Embed lyrics from parallel fetch
+	if req.EmbedLyrics && parallelResult != nil && parallelResult.LyricsLRC != "" {
+		GoLog("[Amazon] Embedding parallel-fetched lyrics (%d lines)...\n", len(parallelResult.LyricsData.Lines))
+		if embedErr := EmbedLyrics(outputPath, parallelResult.LyricsLRC); embedErr != nil {
+			GoLog("[Amazon] Warning: failed to embed lyrics: %v\n", embedErr)
 		} else {
-			fmt.Printf("[Amazon] Lyrics found (%d lines), embedding...\n", len(lyrics.Lines))
-			
-			// Convert Japanese lyrics to romaji if enabled
-			if req.ConvertLyricsToRomaji {
-				for i := range lyrics.Lines {
-					if ContainsKana(lyrics.Lines[i].Words) {
-						lyrics.Lines[i].Words = ToRomaji(lyrics.Lines[i].Words)
-					}
-				}
-				fmt.Println("[Amazon] Converted Japanese lyrics to romaji")
-			}
-			
-			lrcContent := convertToLRC(lyrics)
-			if embedErr := EmbedLyrics(outputPath, lrcContent); embedErr != nil {
-				fmt.Printf("[Amazon] Warning: failed to embed lyrics: %v\n", embedErr)
-			} else {
-				fmt.Println("[Amazon] Lyrics embedded successfully")
-			}
+			fmt.Println("[Amazon] Lyrics embedded successfully")
 		}
+	} else if req.EmbedLyrics {
+		fmt.Println("[Amazon] No lyrics available from parallel fetch")
 	}
 
 	fmt.Println("[Amazon] ✓ Downloaded successfully from Amazon Music")
-	return outputPath, nil
+
+	// Read actual quality from the downloaded FLAC file
+	// Amazon API doesn't provide quality info, but we can read it from the file itself
+	quality, err := GetAudioQuality(outputPath)
+	if err != nil {
+		GoLog("[Amazon] Warning: couldn't read quality from file: %v\n", err)
+	} else {
+		GoLog("[Amazon] Actual quality: %d-bit/%dHz\n", quality.BitDepth, quality.SampleRate)
+	}
+
+	// Read metadata from file AFTER embedding to get accurate values
+	// This ensures we return what's actually in the file
+	finalMeta, metaReadErr := ReadMetadata(outputPath)
+	if metaReadErr == nil && finalMeta != nil {
+		GoLog("[Amazon] Final metadata from file - Track: %d, Disc: %d, Date: %s\n",
+			finalMeta.TrackNumber, finalMeta.DiscNumber, finalMeta.Date)
+		actualTrackNum = finalMeta.TrackNumber
+		actualDiscNum = finalMeta.DiscNumber
+		if finalMeta.Date != "" {
+			// Use date from file if available
+			req.ReleaseDate = finalMeta.Date
+		}
+	}
+
+	// Add to ISRC index for fast duplicate checking
+	AddToISRCIndex(req.OutputDir, req.ISRC, outputPath)
+
+	bitDepth := 0
+	sampleRate := 0
+	if err == nil {
+		bitDepth = quality.BitDepth
+		sampleRate = quality.SampleRate
+	}
+
+	return AmazonDownloadResult{
+		FilePath:    outputPath,
+		BitDepth:    bitDepth,
+		SampleRate:  sampleRate,
+		Title:       req.TrackName,
+		Artist:      req.ArtistName,
+		Album:       req.AlbumName,
+		ReleaseDate: req.ReleaseDate,
+		TrackNumber: actualTrackNum,
+		DiscNumber:  actualDiscNum,
+		ISRC:        req.ISRC,
+	}, nil
 }

go_backend/deezer.go

@@ -0,0 +1,742 @@
+package gobackend
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"sync"
+	"time"
+)
+
+const (
+	deezerBaseURL     = "https://api.deezer.com/2.0"
+	deezerSearchURL   = deezerBaseURL + "/search"
+	deezerTrackURL    = deezerBaseURL + "/track/%s"
+	deezerAlbumURL    = deezerBaseURL + "/album/%s"
+	deezerArtistURL   = deezerBaseURL + "/artist/%s"
+	deezerPlaylistURL = deezerBaseURL + "/playlist/%s"
+
+	deezerCacheTTL = 10 * time.Minute
+
+	// Parallel ISRC fetching settings
+	deezerMaxParallelISRC = 10 // Max concurrent ISRC fetches
+)
+
+// DeezerClient handles Deezer API interactions (no auth required)
+type DeezerClient struct {
+	httpClient  *http.Client
+	searchCache map[string]*cacheEntry
+	albumCache  map[string]*cacheEntry
+	artistCache map[string]*cacheEntry
+	isrcCache   map[string]string // trackID -> ISRC cache
+	cacheMu     sync.RWMutex
+}
+
+// Singleton instance
+var (
+	deezerClient     *DeezerClient
+	deezerClientOnce sync.Once
+)
+
+// GetDeezerClient returns singleton Deezer client
+func GetDeezerClient() *DeezerClient {
+	deezerClientOnce.Do(func() {
+		deezerClient = &DeezerClient{
+			httpClient:  NewHTTPClientWithTimeout(15 * time.Second),
+			searchCache: make(map[string]*cacheEntry),
+			albumCache:  make(map[string]*cacheEntry),
+			artistCache: make(map[string]*cacheEntry),
+			isrcCache:   make(map[string]string),
+		}
+	})
+	return deezerClient
+}
+
+// Deezer API response types
+type deezerTrack struct {
+	ID            int64             `json:"id"`
+	Title         string            `json:"title"`
+	Duration      int               `json:"duration"` // in seconds
+	TrackPosition int               `json:"track_position"`
+	DiskNumber    int               `json:"disk_number"`
+	ISRC          string            `json:"isrc"`
+	Link          string            `json:"link"`
+	ReleaseDate   string            `json:"release_date"` // Sometimes at track level
+	Artist        deezerArtist      `json:"artist"`
+	Album         deezerAlbumSimple `json:"album"`
+	Contributors  []deezerArtist    `json:"contributors"`
+}
+
+type deezerArtist struct {
+	ID            int64  `json:"id"`
+	Name          string `json:"name"`
+	Picture       string `json:"picture"`
+	PictureMedium string `json:"picture_medium"`
+	PictureBig    string `json:"picture_big"`
+	PictureXL     string `json:"picture_xl"`
+	NbFan         int    `json:"nb_fan"`
+}
+
+type deezerAlbumSimple struct {
+	ID          int64  `json:"id"`
+	Title       string `json:"title"`
+	Cover       string `json:"cover"`
+	CoverMedium string `json:"cover_medium"`
+	CoverBig    string `json:"cover_big"`
+	CoverXL     string `json:"cover_xl"`
+	ReleaseDate string `json:"release_date"` // Sometimes at album level
+}
+
+// ... (skip other structs as they are fine/unchanged) ...
+
+// ... (in convertTrack) ...
+func (c *DeezerClient) convertTrack(track deezerTrack) TrackMetadata {
+	artistName := track.Artist.Name
+	if len(track.Contributors) > 0 {
+		names := make([]string, len(track.Contributors))
+		for i, a := range track.Contributors {
+			names[i] = a.Name
+		}
+		artistName = strings.Join(names, ", ")
+	}
+
+	albumImage := track.Album.CoverXL
+	if albumImage == "" {
+		albumImage = track.Album.CoverBig
+	}
+	if albumImage == "" {
+		albumImage = track.Album.CoverMedium
+	}
+	if albumImage == "" {
+		albumImage = track.Album.Cover
+	}
+
+	// Try to find release date
+	releaseDate := track.ReleaseDate
+	if releaseDate == "" {
+		releaseDate = track.Album.ReleaseDate
+	}
+
+	return TrackMetadata{
+		SpotifyID:   fmt.Sprintf("deezer:%d", track.ID),
+		Artists:     artistName,
+		Name:        track.Title,
+		AlbumName:   track.Album.Title,
+		AlbumArtist: track.Artist.Name,
+		DurationMS:  track.Duration * 1000,
+		Images:      albumImage,
+		ReleaseDate: releaseDate, // Added this
+		TrackNumber: track.TrackPosition,
+		DiscNumber:  track.DiskNumber,
+		ExternalURL: track.Link,
+		ISRC:        track.ISRC,
+	}
+}
+
+type deezerAlbumFull struct {
+	ID           int64          `json:"id"`
+	Title        string         `json:"title"`
+	Cover        string         `json:"cover"`
+	CoverMedium  string         `json:"cover_medium"`
+	CoverBig     string         `json:"cover_big"`
+	CoverXL      string         `json:"cover_xl"`
+	ReleaseDate  string         `json:"release_date"`
+	NbTracks     int            `json:"nb_tracks"`
+	Artist       deezerArtist   `json:"artist"`
+	Contributors []deezerArtist `json:"contributors"`
+	Tracks       struct {
+		Data []deezerTrack `json:"data"`
+	} `json:"tracks"`
+}
+
+type deezerArtistFull struct {
+	ID            int64  `json:"id"`
+	Name          string `json:"name"`
+	Picture       string `json:"picture"`
+	PictureMedium string `json:"picture_medium"`
+	PictureBig    string `json:"picture_big"`
+	PictureXL     string `json:"picture_xl"`
+	NbFan         int    `json:"nb_fan"`
+	NbAlbum       int    `json:"nb_album"`
+}
+
+type deezerPlaylistFull struct {
+	ID            int64  `json:"id"`
+	Title         string `json:"title"`
+	Picture       string `json:"picture"`
+	PictureMedium string `json:"picture_medium"`
+	PictureBig    string `json:"picture_big"`
+	PictureXL     string `json:"picture_xl"`
+	NbTracks      int    `json:"nb_tracks"`
+	Creator       struct {
+		Name string `json:"name"`
+	} `json:"creator"`
+	Tracks struct {
+		Data []deezerTrack `json:"data"`
+	} `json:"tracks"`
+}
+
+// SearchAll searches for tracks and artists on Deezer
+// NOTE: ISRC is NOT fetched during search for performance - use GetTrackISRC when needed for download
+func (c *DeezerClient) SearchAll(ctx context.Context, query string, trackLimit, artistLimit int) (*SearchAllResult, error) {
+	GoLog("[Deezer] SearchAll: query=%q, trackLimit=%d, artistLimit=%d\n", query, trackLimit, artistLimit)
+
+	cacheKey := fmt.Sprintf("deezer:all:%s:%d:%d", query, trackLimit, artistLimit)
+
+	c.cacheMu.RLock()
+	if entry, ok := c.searchCache[cacheKey]; ok && !entry.isExpired() {
+		c.cacheMu.RUnlock()
+		GoLog("[Deezer] SearchAll: returning cached result\n")
+		return entry.data.(*SearchAllResult), nil
+	}
+	c.cacheMu.RUnlock()
+
+	result := &SearchAllResult{
+		Tracks:  make([]TrackMetadata, 0),
+		Artists: make([]SearchArtistResult, 0),
+	}
+
+	// Search tracks - NO ISRC fetch for performance
+	trackURL := fmt.Sprintf("%s/track?q=%s&limit=%d", deezerSearchURL, url.QueryEscape(query), trackLimit)
+	GoLog("[Deezer] Fetching tracks from: %s\n", trackURL)
+
+	var trackResp struct {
+		Data  []deezerTrack `json:"data"`
+		Error *struct {
+			Type    string `json:"type"`
+			Message string `json:"message"`
+			Code    int    `json:"code"`
+		} `json:"error"`
+	}
+	if err := c.getJSON(ctx, trackURL, &trackResp); err != nil {
+		GoLog("[Deezer] Track search failed: %v\n", err)
+		return nil, fmt.Errorf("deezer track search failed: %w", err)
+	}
+
+	if trackResp.Error != nil {
+		GoLog("[Deezer] API error: type=%s, code=%d, message=%s\n", trackResp.Error.Type, trackResp.Error.Code, trackResp.Error.Message)
+		return nil, fmt.Errorf("deezer API error: %s (code %d)", trackResp.Error.Message, trackResp.Error.Code)
+	}
+
+	GoLog("[Deezer] Got %d tracks from API\n", len(trackResp.Data))
+
+	for _, track := range trackResp.Data {
+		// Convert directly without fetching ISRC - much faster
+		result.Tracks = append(result.Tracks, c.convertTrack(track))
+	}
+
+	// Search artists
+	artistURL := fmt.Sprintf("%s/artist?q=%s&limit=%d", deezerSearchURL, url.QueryEscape(query), artistLimit)
+	GoLog("[Deezer] Fetching artists from: %s\n", artistURL)
+
+	var artistResp struct {
+		Data  []deezerArtist `json:"data"`
+		Error *struct {
+			Type    string `json:"type"`
+			Message string `json:"message"`
+			Code    int    `json:"code"`
+		} `json:"error"`
+	}
+	if err := c.getJSON(ctx, artistURL, &artistResp); err == nil {
+		if artistResp.Error != nil {
+			GoLog("[Deezer] Artist API error: type=%s, code=%d, message=%s\n", artistResp.Error.Type, artistResp.Error.Code, artistResp.Error.Message)
+		} else {
+			GoLog("[Deezer] Got %d artists from API\n", len(artistResp.Data))
+			for _, artist := range artistResp.Data {
+				result.Artists = append(result.Artists, SearchArtistResult{
+					ID:         fmt.Sprintf("deezer:%d", artist.ID),
+					Name:       artist.Name,
+					Images:     c.getBestArtistImage(artist),
+					Followers:  artist.NbFan,
+					Popularity: 0,
+				})
+			}
+		}
+	} else {
+		GoLog("[Deezer] Artist search failed: %v\n", err)
+	}
+
+	GoLog("[Deezer] SearchAll complete: %d tracks, %d artists\n", len(result.Tracks), len(result.Artists))
+
+	// Cache result
+	c.cacheMu.Lock()
+	c.searchCache[cacheKey] = &cacheEntry{
+		data:      result,
+		expiresAt: time.Now().Add(deezerCacheTTL),
+	}
+	c.cacheMu.Unlock()
+
+	return result, nil
+}
+
+// GetTrack fetches a single track by Deezer ID
+func (c *DeezerClient) GetTrack(ctx context.Context, trackID string) (*TrackResponse, error) {
+	trackURL := fmt.Sprintf(deezerTrackURL, trackID)
+
+	var track deezerTrack
+	if err := c.getJSON(ctx, trackURL, &track); err != nil {
+		return nil, err
+	}
+
+	return &TrackResponse{
+		Track: c.convertTrack(track),
+	}, nil
+}
+
+// GetAlbum fetches album with tracks
+// ISRC is fetched in parallel for better performance
+func (c *DeezerClient) GetAlbum(ctx context.Context, albumID string) (*AlbumResponsePayload, error) {
+	c.cacheMu.RLock()
+	if entry, ok := c.albumCache[albumID]; ok && !entry.isExpired() {
+		c.cacheMu.RUnlock()
+		return entry.data.(*AlbumResponsePayload), nil
+	}
+	c.cacheMu.RUnlock()
+
+	albumURL := fmt.Sprintf(deezerAlbumURL, albumID)
+
+	var album deezerAlbumFull
+	if err := c.getJSON(ctx, albumURL, &album); err != nil {
+		return nil, err
+	}
+
+	albumImage := c.getBestAlbumImage(album)
+	artistName := album.Artist.Name
+	if len(album.Contributors) > 0 {
+		names := make([]string, len(album.Contributors))
+		for i, a := range album.Contributors {
+			names[i] = a.Name
+		}
+		artistName = strings.Join(names, ", ")
+	}
+
+	info := AlbumInfoMetadata{
+		TotalTracks: album.NbTracks,
+		Name:        album.Title,
+		ReleaseDate: album.ReleaseDate,
+		Artists:     artistName,
+		Images:      albumImage,
+	}
+
+	// Fetch ISRCs in parallel
+	isrcMap := c.fetchISRCsParallel(ctx, album.Tracks.Data)
+
+	tracks := make([]AlbumTrackMetadata, 0, len(album.Tracks.Data))
+	for _, track := range album.Tracks.Data {
+		trackIDStr := fmt.Sprintf("%d", track.ID)
+		isrc := isrcMap[trackIDStr]
+
+		tracks = append(tracks, AlbumTrackMetadata{
+			SpotifyID:   fmt.Sprintf("deezer:%d", track.ID),
+			Artists:     track.Artist.Name,
+			Name:        track.Title,
+			AlbumName:   album.Title,
+			AlbumArtist: artistName,
+			DurationMS:  track.Duration * 1000,
+			Images:      albumImage,
+			ReleaseDate: album.ReleaseDate,
+			TrackNumber: track.TrackPosition,
+			TotalTracks: album.NbTracks,
+			DiscNumber:  track.DiskNumber,
+			ExternalURL: track.Link,
+			ISRC:        isrc,
+			AlbumID:     fmt.Sprintf("deezer:%d", album.ID),
+		})
+	}
+
+	result := &AlbumResponsePayload{
+		AlbumInfo: info,
+		TrackList: tracks,
+	}
+
+	c.cacheMu.Lock()
+	c.albumCache[albumID] = &cacheEntry{
+		data:      result,
+		expiresAt: time.Now().Add(deezerCacheTTL),
+	}
+	c.cacheMu.Unlock()
+
+	return result, nil
+}
+
+// GetArtist fetches artist with albums
+func (c *DeezerClient) GetArtist(ctx context.Context, artistID string) (*ArtistResponsePayload, error) {
+	c.cacheMu.RLock()
+	if entry, ok := c.artistCache[artistID]; ok && !entry.isExpired() {
+		c.cacheMu.RUnlock()
+		return entry.data.(*ArtistResponsePayload), nil
+	}
+	c.cacheMu.RUnlock()
+
+	// Fetch artist info
+	artistURL := fmt.Sprintf(deezerArtistURL, artistID)
+	var artist deezerArtistFull
+	if err := c.getJSON(ctx, artistURL, &artist); err != nil {
+		return nil, err
+	}
+
+	artistInfo := ArtistInfoMetadata{
+		ID:         fmt.Sprintf("deezer:%d", artist.ID),
+		Name:       artist.Name,
+		Images:     c.getBestArtistImageFull(artist),
+		Followers:  artist.NbFan,
+		Popularity: 0,
+	}
+
+	// Fetch artist albums
+	albumsURL := fmt.Sprintf("%s/albums?limit=100", fmt.Sprintf(deezerArtistURL, artistID))
+	var albumsResp struct {
+		Data []struct {
+			ID          int64  `json:"id"`
+			Title       string `json:"title"`
+			ReleaseDate string `json:"release_date"`
+			NbTracks    int    `json:"nb_tracks"`
+			Cover       string `json:"cover"`
+			CoverMedium string `json:"cover_medium"`
+			CoverBig    string `json:"cover_big"`
+			CoverXL     string `json:"cover_xl"`
+			RecordType  string `json:"record_type"` // album, single, ep, compile
+		} `json:"data"`
+	}
+
+	albums := make([]ArtistAlbumMetadata, 0)
+	if err := c.getJSON(ctx, albumsURL, &albumsResp); err == nil {
+		for _, album := range albumsResp.Data {
+			albumType := album.RecordType
+			if albumType == "compile" {
+				albumType = "compilation"
+			}
+
+			coverURL := album.CoverXL
+			if coverURL == "" {
+				coverURL = album.CoverBig
+			}
+			if coverURL == "" {
+				coverURL = album.CoverMedium
+			}
+			if coverURL == "" {
+				coverURL = album.Cover
+			}
+
+			albums = append(albums, ArtistAlbumMetadata{
+				ID:          fmt.Sprintf("deezer:%d", album.ID),
+				Name:        album.Title,
+				ReleaseDate: album.ReleaseDate,
+				TotalTracks: album.NbTracks,
+				Images:      coverURL,
+				AlbumType:   albumType,
+				Artists:     artist.Name,
+			})
+		}
+	}
+
+	result := &ArtistResponsePayload{
+		ArtistInfo: artistInfo,
+		Albums:     albums,
+	}
+
+	c.cacheMu.Lock()
+	c.artistCache[artistID] = &cacheEntry{
+		data:      result,
+		expiresAt: time.Now().Add(deezerCacheTTL),
+	}
+	c.cacheMu.Unlock()
+
+	return result, nil
+}
+
+// GetPlaylist fetches playlist with tracks
+// ISRC is fetched in parallel for better performance
+func (c *DeezerClient) GetPlaylist(ctx context.Context, playlistID string) (*PlaylistResponsePayload, error) {
+	playlistURL := fmt.Sprintf(deezerPlaylistURL, playlistID)
+
+	var playlist deezerPlaylistFull
+	if err := c.getJSON(ctx, playlistURL, &playlist); err != nil {
+		return nil, err
+	}
+
+	playlistImage := playlist.PictureXL
+	if playlistImage == "" {
+		playlistImage = playlist.PictureBig
+	}
+	if playlistImage == "" {
+		playlistImage = playlist.PictureMedium
+	}
+
+	var info PlaylistInfoMetadata
+	info.Tracks.Total = playlist.NbTracks
+	info.Owner.DisplayName = playlist.Creator.Name
+	info.Owner.Name = playlist.Title
+	info.Owner.Images = playlistImage
+
+	// Fetch ISRCs in parallel
+	isrcMap := c.fetchISRCsParallel(ctx, playlist.Tracks.Data)
+
+	tracks := make([]AlbumTrackMetadata, 0, len(playlist.Tracks.Data))
+	for _, track := range playlist.Tracks.Data {
+		albumImage := track.Album.CoverXL
+		if albumImage == "" {
+			albumImage = track.Album.CoverBig
+		}
+		if albumImage == "" {
+			albumImage = track.Album.CoverMedium
+		}
+
+		trackIDStr := fmt.Sprintf("%d", track.ID)
+		isrc := isrcMap[trackIDStr]
+
+		tracks = append(tracks, AlbumTrackMetadata{
+			SpotifyID:   fmt.Sprintf("deezer:%d", track.ID),
+			Artists:     track.Artist.Name,
+			Name:        track.Title,
+			AlbumName:   track.Album.Title,
+			AlbumArtist: track.Artist.Name,
+			DurationMS:  track.Duration * 1000,
+			Images:      albumImage,
+			ReleaseDate: "",
+			TrackNumber: track.TrackPosition,
+			DiscNumber:  track.DiskNumber,
+			ExternalURL: track.Link,
+			ISRC:        isrc,
+			AlbumID:     fmt.Sprintf("deezer:%d", track.Album.ID),
+		})
+	}
+
+	return &PlaylistResponsePayload{
+		PlaylistInfo: info,
+		TrackList:    tracks,
+	}, nil
+}
+
+// SearchByISRC searches for a track by ISRC using direct endpoint
+func (c *DeezerClient) SearchByISRC(ctx context.Context, isrc string) (*TrackMetadata, error) {
+	// Use direct ISRC endpoint (API 2.0)
+	// https://api.deezer.com/2.0/track/isrc:{ISRC}
+	directURL := fmt.Sprintf("%s/track/isrc:%s", deezerBaseURL, isrc)
+
+	var track deezerTrack
+	if err := c.getJSON(ctx, directURL, &track); err != nil {
+		// Fallback to search if direct endpoint fails
+		searchURL := fmt.Sprintf("%s/track?q=isrc:%s&limit=1", deezerSearchURL, isrc)
+		var resp struct {
+			Data []deezerTrack `json:"data"`
+		}
+		if err := c.getJSON(ctx, searchURL, &resp); err != nil {
+			return nil, err
+		}
+		if len(resp.Data) == 0 {
+			return nil, fmt.Errorf("no track found for ISRC: %s", isrc)
+		}
+		result := c.convertTrack(resp.Data[0])
+		return &result, nil
+	}
+
+	// Check if we got a valid response (ID > 0)
+	if track.ID == 0 {
+		return nil, fmt.Errorf("no track found for ISRC: %s", isrc)
+	}
+
+	result := c.convertTrack(track)
+	return &result, nil
+}
+
+func (c *DeezerClient) fetchFullTrack(ctx context.Context, trackID string) (*deezerTrack, error) {
+	trackURL := fmt.Sprintf(deezerTrackURL, trackID)
+	var track deezerTrack
+	if err := c.getJSON(ctx, trackURL, &track); err != nil {
+		return nil, err
+	}
+	return &track, nil
+}
+
+// fetchISRCsParallel fetches ISRCs for multiple tracks in parallel with caching
+func (c *DeezerClient) fetchISRCsParallel(ctx context.Context, tracks []deezerTrack) map[string]string {
+	result := make(map[string]string)
+	var resultMu sync.Mutex
+
+	// First, check cache for existing ISRCs
+	var tracksToFetch []deezerTrack
+	c.cacheMu.RLock()
+	for _, track := range tracks {
+		trackIDStr := fmt.Sprintf("%d", track.ID)
+		if isrc, ok := c.isrcCache[trackIDStr]; ok {
+			result[trackIDStr] = isrc
+		} else {
+			tracksToFetch = append(tracksToFetch, track)
+		}
+	}
+	c.cacheMu.RUnlock()
+
+	if len(tracksToFetch) == 0 {
+		return result
+	}
+
+	// Use semaphore to limit concurrent requests
+	sem := make(chan struct{}, deezerMaxParallelISRC)
+	var wg sync.WaitGroup
+
+	for _, track := range tracksToFetch {
+		wg.Add(1)
+		go func(t deezerTrack) {
+			defer wg.Done()
+
+			// Acquire semaphore
+			select {
+			case sem <- struct{}{}:
+				defer func() { <-sem }()
+			case <-ctx.Done():
+				return
+			}
+
+			trackIDStr := fmt.Sprintf("%d", t.ID)
+			fullTrack, err := c.fetchFullTrack(ctx, trackIDStr)
+			if err != nil || fullTrack == nil {
+				return
+			}
+
+			// Store in result and cache
+			resultMu.Lock()
+			result[trackIDStr] = fullTrack.ISRC
+			resultMu.Unlock()
+
+			c.cacheMu.Lock()
+			c.isrcCache[trackIDStr] = fullTrack.ISRC
+			c.cacheMu.Unlock()
+		}(track)
+	}
+
+	wg.Wait()
+	return result
+}
+
+// GetTrackISRC fetches ISRC for a single track (with caching)
+// Use this when you need ISRC for download
+func (c *DeezerClient) GetTrackISRC(ctx context.Context, trackID string) (string, error) {
+	// Check cache first
+	c.cacheMu.RLock()
+	if isrc, ok := c.isrcCache[trackID]; ok {
+		c.cacheMu.RUnlock()
+		return isrc, nil
+	}
+	c.cacheMu.RUnlock()
+
+	// Fetch from API
+	fullTrack, err := c.fetchFullTrack(ctx, trackID)
+	if err != nil {
+		return "", err
+	}
+
+	// Cache the result
+	c.cacheMu.Lock()
+	c.isrcCache[trackID] = fullTrack.ISRC
+	c.cacheMu.Unlock()
+
+	return fullTrack.ISRC, nil
+}
+
+func (c *DeezerClient) getBestArtistImage(artist deezerArtist) string {
+	if artist.PictureXL != "" {
+		return artist.PictureXL
+	}
+	if artist.PictureBig != "" {
+		return artist.PictureBig
+	}
+	if artist.PictureMedium != "" {
+		return artist.PictureMedium
+	}
+	return artist.Picture
+}
+
+func (c *DeezerClient) getBestArtistImageFull(artist deezerArtistFull) string {
+	if artist.PictureXL != "" {
+		return artist.PictureXL
+	}
+	if artist.PictureBig != "" {
+		return artist.PictureBig
+	}
+	if artist.PictureMedium != "" {
+		return artist.PictureMedium
+	}
+	return artist.Picture
+}
+
+func (c *DeezerClient) getBestAlbumImage(album deezerAlbumFull) string {
+	if album.CoverXL != "" {
+		return album.CoverXL
+	}
+	if album.CoverBig != "" {
+		return album.CoverBig
+	}
+	if album.CoverMedium != "" {
+		return album.CoverMedium
+	}
+	return album.Cover
+}
+
+func (c *DeezerClient) getJSON(ctx context.Context, endpoint string, dst interface{}) error {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
+	if err != nil {
+		return err
+	}
+
+	req.Header.Set("Accept", "application/json")
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("deezer API returned status %d: %s", resp.StatusCode, string(body))
+	}
+
+	return json.Unmarshal(body, dst)
+}
+
+// parseDeezerURL is internal function, returns type and ID
+func parseDeezerURL(input string) (string, string, error) {
+	trimmed := strings.TrimSpace(input)
+	if trimmed == "" {
+		return "", "", fmt.Errorf("empty URL")
+	}
+
+	parsed, err := url.Parse(trimmed)
+	if err != nil {
+		return "", "", err
+	}
+
+	if parsed.Host != "www.deezer.com" && parsed.Host != "deezer.com" && parsed.Host != "deezer.page.link" {
+		return "", "", fmt.Errorf("not a Deezer URL")
+	}
+
+	parts := strings.Split(strings.Trim(parsed.Path, "/"), "/")
+
+	// Skip language prefix if present (e.g., /en/, /fr/)
+	if len(parts) > 0 && len(parts[0]) == 2 {
+		parts = parts[1:]
+	}
+
+	if len(parts) < 2 {
+		return "", "", fmt.Errorf("invalid Deezer URL format")
+	}
+
+	resourceType := parts[0]
+	resourceID := parts[1]
+
+	switch resourceType {
+	case "track", "album", "artist", "playlist":
+		return resourceType, resourceID, nil
+	default:
+		return "", "", fmt.Errorf("unsupported Deezer resource type: %s", resourceType)
+	}
+}

go_backend/duplicate.go

@@ -1,49 +1,144 @@
 package gobackend
 
 import (
+	"encoding/json"
+	"fmt"
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
+	"time"
 )
 
+// ISRCIndex holds a cached map of ISRC -> file path for fast duplicate checking
+type ISRCIndex struct {
+	index     map[string]string // ISRC (uppercase) -> file path
+	outputDir string
+	buildTime time.Time
+	mu        sync.RWMutex
+}
+
+// Global ISRC index cache (per output directory)
+var (
+	isrcIndexCache   = make(map[string]*ISRCIndex)
+	isrcIndexCacheMu sync.RWMutex
+	isrcIndexTTL     = 5 * time.Minute // Cache TTL - rebuild after 5 minutes
+)
+
+// GetISRCIndex returns or builds an ISRC index for the given directory
+func GetISRCIndex(outputDir string) *ISRCIndex {
+	isrcIndexCacheMu.RLock()
+	idx, exists := isrcIndexCache[outputDir]
+	isrcIndexCacheMu.RUnlock()
+
+	// Return cached index if still valid
+	if exists && time.Since(idx.buildTime) < isrcIndexTTL {
+		return idx
+	}
+
+	// Build new index
+	return buildISRCIndex(outputDir)
+}
+
+// buildISRCIndex scans a directory and builds a map of ISRC -> file path
+// Same implementation as PC version for consistency
+func buildISRCIndex(outputDir string) *ISRCIndex {
+	idx := &ISRCIndex{
+		index:     make(map[string]string),
+		outputDir: outputDir,
+		buildTime: time.Now(),
+	}
+
+	if outputDir == "" {
+		return idx
+	}
+
+	startTime := time.Now()
+	fileCount := 0
+
+	// Walk directory - only check .flac files
+	filepath.Walk(outputDir, func(path string, info os.FileInfo, err error) error {
+		if err != nil || info.IsDir() {
+			return nil
+		}
+
+		ext := strings.ToLower(filepath.Ext(path))
+		if ext != ".flac" {
+			return nil
+		}
+
+		// Read ISRC from file
+		metadata, err := ReadMetadata(path)
+		if err != nil || metadata.ISRC == "" {
+			return nil
+		}
+
+		// Store in index (uppercase for case-insensitive matching)
+		idx.index[strings.ToUpper(metadata.ISRC)] = path
+		fileCount++
+		return nil
+	})
+
+	fmt.Printf("[ISRCIndex] Built index for %s: %d files in %v\n", 
+		outputDir, fileCount, time.Since(startTime).Round(time.Millisecond))
+
+	// Cache the index
+	isrcIndexCacheMu.Lock()
+	isrcIndexCache[outputDir] = idx
+	isrcIndexCacheMu.Unlock()
+
+	return idx
+}
+
+// lookup checks if an ISRC exists in the index (internal, returns bool)
+func (idx *ISRCIndex) lookup(isrc string) (string, bool) {
+	if isrc == "" {
+		return "", false
+	}
+
+	idx.mu.RLock()
+	defer idx.mu.RUnlock()
+
+	path, exists := idx.index[strings.ToUpper(isrc)]
+	return path, exists
+}
+
+// Lookup checks if an ISRC exists in the index (gomobile compatible)
+// Returns filepath if found, empty string if not found
+func (idx *ISRCIndex) Lookup(isrc string) (string, error) {
+	path, _ := idx.lookup(isrc)
+	return path, nil
+}
+
+// Add adds a new ISRC to the index (call after successful download)
+func (idx *ISRCIndex) Add(isrc, filePath string) {
+	if isrc == "" || filePath == "" {
+		return
+	}
+
+	idx.mu.Lock()
+	defer idx.mu.Unlock()
+
+	idx.index[strings.ToUpper(isrc)] = filePath
+}
+
+// InvalidateCache clears the ISRC index cache for a directory
+func InvalidateISRCCache(outputDir string) {
+	isrcIndexCacheMu.Lock()
+	delete(isrcIndexCache, outputDir)
+	isrcIndexCacheMu.Unlock()
+}
+
 // checkISRCExistsInternal checks if a file with the given ISRC exists (internal use)
+// Uses ISRC index for fast lookup
 func checkISRCExistsInternal(outputDir, isrc string) (string, bool) {
 	if isrc == "" || outputDir == "" {
 		return "", false
 	}
 
-	// Walk through directory looking for FLAC files
-	var foundFile string
-	filepath.Walk(outputDir, func(path string, info os.FileInfo, err error) error {
-		if err != nil {
-			return nil
-		}
-
-		// Only check FLAC files
-		if info.IsDir() || !strings.HasSuffix(strings.ToLower(path), ".flac") {
-			return nil
-		}
-
-		// Read metadata from file
-		metadata, err := ReadMetadata(path)
-		if err != nil {
-			return nil
-		}
-
-		// Check if ISRC matches
-		if metadata.ISRC == isrc {
-			foundFile = path
-			return filepath.SkipAll // Stop walking
-		}
-
-		return nil
-	})
-
-	if foundFile != "" {
-		return foundFile, true
-	}
-
-	return "", false
+	// Use index for fast lookup
+	idx := GetISRCIndex(outputDir)
+	return idx.lookup(isrc)
 }
 
 // CheckISRCExists is the exported version for gomobile (returns string, error)
@@ -61,3 +156,98 @@ func CheckFileExists(filePath string) bool {
 	}
 	return !info.IsDir() && info.Size() > 0
 }
+
+// FileExistenceResult represents the result of checking if a file exists
+type FileExistenceResult struct {
+	ISRC       string `json:"isrc"`
+	Exists     bool   `json:"exists"`
+	FilePath   string `json:"file_path,omitempty"`
+	TrackName  string `json:"track_name,omitempty"`
+	ArtistName string `json:"artist_name,omitempty"`
+}
+
+// CheckFilesExistParallel checks if multiple files exist in parallel
+// It builds an ISRC index from the output directory once, then checks all tracks against it
+// Same implementation as PC version for consistency
+func CheckFilesExistParallel(outputDir string, tracksJSON string) (string, error) {
+	// Parse input JSON
+	var tracks []struct {
+		ISRC       string `json:"isrc"`
+		TrackName  string `json:"track_name"`
+		ArtistName string `json:"artist_name"`
+	}
+	if err := json.Unmarshal([]byte(tracksJSON), &tracks); err != nil {
+		return "", fmt.Errorf("failed to parse tracks JSON: %w", err)
+	}
+
+	results := make([]FileExistenceResult, len(tracks))
+
+	// Build ISRC index from output directory (scan once)
+	isrcIdx := GetISRCIndex(outputDir)
+
+	// Check each track against the index (parallel)
+	var wg sync.WaitGroup
+	for i, track := range tracks {
+		wg.Add(1)
+		go func(resultIdx int, t struct {
+			ISRC       string `json:"isrc"`
+			TrackName  string `json:"track_name"`
+			ArtistName string `json:"artist_name"`
+		}) {
+			defer wg.Done()
+
+			result := FileExistenceResult{
+				ISRC:       t.ISRC,
+				TrackName:  t.TrackName,
+				ArtistName: t.ArtistName,
+				Exists:     false,
+			}
+
+			if t.ISRC != "" {
+				if filePath, exists := isrcIdx.lookup(t.ISRC); exists {
+					result.Exists = true
+					result.FilePath = filePath
+				}
+			}
+
+			results[resultIdx] = result
+		}(i, track)
+	}
+
+	wg.Wait()
+
+	// Return results as JSON
+	resultJSON, err := json.Marshal(results)
+	if err != nil {
+		return "", fmt.Errorf("failed to marshal results: %w", err)
+	}
+
+	return string(resultJSON), nil
+}
+
+// PreBuildISRCIndex pre-builds the ISRC index for a directory
+// Call this when app starts or when entering album/playlist screen
+func PreBuildISRCIndex(outputDir string) error {
+	if outputDir == "" {
+		return fmt.Errorf("output directory is required")
+	}
+
+	buildISRCIndex(outputDir)
+	return nil
+}
+
+// AddToISRCIndex adds a new file to the ISRC index after successful download
+// This avoids rebuilding the entire index
+func AddToISRCIndex(outputDir, isrc, filePath string) {
+	if outputDir == "" || isrc == "" || filePath == "" {
+		return
+	}
+
+	isrcIndexCacheMu.RLock()
+	idx, exists := isrcIndexCache[outputDir]
+	isrcIndexCacheMu.RUnlock()
+
+	if exists {
+		idx.Add(isrc, filePath)
+	}
+}

go_backend/extension_manager.go

@@ -0,0 +1,986 @@
+// Package gobackend provides extension management functionality
+package gobackend
+
+import (
+	"archive/zip"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+
+	"github.com/dop251/goja"
+)
+
+// compareVersions compares two semantic version strings
+// Returns: -1 if v1 < v2, 0 if v1 == v2, 1 if v1 > v2
+func compareVersions(v1, v2 string) int {
+	// Parse version parts
+	parts1 := strings.Split(strings.TrimPrefix(v1, "v"), ".")
+	parts2 := strings.Split(strings.TrimPrefix(v2, "v"), ".")
+
+	// Pad shorter version with zeros
+	maxLen := len(parts1)
+	if len(parts2) > maxLen {
+		maxLen = len(parts2)
+	}
+
+	for i := 0; i < maxLen; i++ {
+		var n1, n2 int
+		if i < len(parts1) {
+			n1, _ = strconv.Atoi(parts1[i])
+		}
+		if i < len(parts2) {
+			n2, _ = strconv.Atoi(parts2[i])
+		}
+
+		if n1 < n2 {
+			return -1
+		}
+		if n1 > n2 {
+			return 1
+		}
+	}
+
+	return 0
+}
+
+// LoadedExtension represents an extension that has been loaded into memory
+type LoadedExtension struct {
+	ID        string             `json:"id"`
+	Manifest  *ExtensionManifest `json:"manifest"`
+	VM        *goja.Runtime      `json:"-"` // Goja VM instance (not serialized)
+	Enabled   bool               `json:"enabled"`
+	Error     string             `json:"error,omitempty"`
+	DataDir   string             `json:"data_dir"`   // Extension's data directory
+	SourceDir string             `json:"source_dir"` // Where extension files are extracted
+	IconPath  string             `json:"icon_path"`  // Full path to icon file (if exists)
+}
+
+// ExtensionManager manages all loaded extensions
+type ExtensionManager struct {
+	mu            sync.RWMutex
+	extensions    map[string]*LoadedExtension
+	extensionsDir string // Base directory for extensions
+	dataDir       string // Base directory for extension data
+}
+
+// Global extension manager instance
+var (
+	globalExtManager     *ExtensionManager
+	globalExtManagerOnce sync.Once
+)
+
+// GetExtensionManager returns the global extension manager instance
+func GetExtensionManager() *ExtensionManager {
+	globalExtManagerOnce.Do(func() {
+		globalExtManager = &ExtensionManager{
+			extensions: make(map[string]*LoadedExtension),
+		}
+	})
+	return globalExtManager
+}
+
+// SetDirectories sets the extensions and data directories
+func (m *ExtensionManager) SetDirectories(extensionsDir, dataDir string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	m.extensionsDir = extensionsDir
+	m.dataDir = dataDir
+
+	// Create directories if they don't exist
+	if err := os.MkdirAll(extensionsDir, 0755); err != nil {
+		return fmt.Errorf("failed to create extensions directory: %w", err)
+	}
+	if err := os.MkdirAll(dataDir, 0755); err != nil {
+		return fmt.Errorf("failed to create data directory: %w", err)
+	}
+
+	return nil
+}
+
+// LoadExtensionFromFile loads an extension from a .spotiflac-ext file
+func (m *ExtensionManager) LoadExtensionFromFile(filePath string) (*LoadedExtension, error) {
+	// Validate file extension
+	if !strings.HasSuffix(strings.ToLower(filePath), ".spotiflac-ext") {
+		return nil, fmt.Errorf("Invalid file format. Please select a .spotiflac-ext file")
+	}
+
+	// Open the zip file
+	zipReader, err := zip.OpenReader(filePath)
+	if err != nil {
+		return nil, fmt.Errorf("Cannot open extension file. The file may be corrupted or not a valid extension package")
+	}
+	defer zipReader.Close()
+
+	// Find and read manifest.json
+	var manifestData []byte
+	var hasIndexJS bool
+	for _, file := range zipReader.File {
+		name := filepath.Base(file.Name)
+		if name == "manifest.json" {
+			rc, err := file.Open()
+			if err != nil {
+				return nil, fmt.Errorf("failed to open manifest.json: %w", err)
+			}
+			manifestData, err = io.ReadAll(rc)
+			rc.Close()
+			if err != nil {
+				return nil, fmt.Errorf("failed to read manifest.json: %w", err)
+			}
+		}
+		if name == "index.js" {
+			hasIndexJS = true
+		}
+	}
+
+	if manifestData == nil {
+		return nil, fmt.Errorf("Invalid extension package: manifest.json not found")
+	}
+
+	if !hasIndexJS {
+		return nil, fmt.Errorf("Invalid extension package: index.js not found")
+	}
+
+	// Parse and validate manifest
+	manifest, err := ParseManifest(manifestData)
+	if err != nil {
+		return nil, fmt.Errorf("Invalid extension manifest: %w", err)
+	}
+
+	// Check if extension already loaded - if so, try upgrade (check without holding lock for long)
+	m.mu.RLock()
+	existing, exists := m.extensions[manifest.Name]
+	var existingVersion string
+	var existingDisplayName string
+	if exists {
+		existingVersion = existing.Manifest.Version
+		existingDisplayName = existing.Manifest.DisplayName
+	}
+	m.mu.RUnlock()
+
+	if exists {
+		// Check if this is an upgrade
+		versionCompare := compareVersions(manifest.Version, existingVersion)
+		if versionCompare > 0 {
+			// This is an upgrade - call UpgradeExtension
+			return m.UpgradeExtension(filePath)
+		} else if versionCompare == 0 {
+			return nil, fmt.Errorf("Extension '%s' v%s is already installed", existingDisplayName, existingVersion)
+		} else {
+			return nil, fmt.Errorf("Cannot downgrade '%s' from v%s to v%s", existingDisplayName, existingVersion, manifest.Version)
+		}
+	}
+
+	// Now acquire write lock for the rest of the operation
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	// Double-check extension wasn't added while we were waiting for lock
+	if _, exists := m.extensions[manifest.Name]; exists {
+		return nil, fmt.Errorf("Extension '%s' was installed by another process", manifest.DisplayName)
+	}
+
+	// Create extension directory
+	extDir := filepath.Join(m.extensionsDir, manifest.Name)
+	if err := os.MkdirAll(extDir, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create extension directory: %w", err)
+	}
+
+	// Extract all files
+	for _, file := range zipReader.File {
+		if file.FileInfo().IsDir() {
+			continue
+		}
+
+		// Get relative path within the zip
+		destPath := filepath.Join(extDir, filepath.Base(file.Name))
+
+		// Create destination file
+		destFile, err := os.Create(destPath)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create file %s: %w", destPath, err)
+		}
+
+		// Copy content
+		srcFile, err := file.Open()
+		if err != nil {
+			destFile.Close()
+			return nil, fmt.Errorf("failed to open file in archive: %w", err)
+		}
+
+		_, err = io.Copy(destFile, srcFile)
+		srcFile.Close()
+		destFile.Close()
+		if err != nil {
+			return nil, fmt.Errorf("failed to extract file: %w", err)
+		}
+	}
+
+	// Create data directory for extension
+	extDataDir := filepath.Join(m.dataDir, manifest.Name)
+	if err := os.MkdirAll(extDataDir, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create extension data directory: %w", err)
+	}
+
+	// Create loaded extension
+	ext := &LoadedExtension{
+		ID:        manifest.Name,
+		Manifest:  manifest,
+		Enabled:   true,
+		DataDir:   extDataDir,
+		SourceDir: extDir,
+	}
+
+	// Initialize Goja VM
+	if err := m.initializeVM(ext); err != nil {
+		ext.Error = err.Error()
+		ext.Enabled = false
+		GoLog("[Extension] Failed to initialize VM for %s: %v\n", manifest.Name, err)
+	}
+
+	m.extensions[manifest.Name] = ext
+	GoLog("[Extension] Loaded extension: %s v%s\n", manifest.DisplayName, manifest.Version)
+
+	return ext, nil
+}
+
+// initializeVM creates and initializes the Goja VM for an extension
+func (m *ExtensionManager) initializeVM(ext *LoadedExtension) error {
+	// Create new Goja runtime
+	vm := goja.New()
+	ext.VM = vm
+
+	// Read index.js
+	indexPath := filepath.Join(ext.SourceDir, "index.js")
+	jsCode, err := os.ReadFile(indexPath)
+	if err != nil {
+		return fmt.Errorf("failed to read index.js: %w", err)
+	}
+
+	// Create extension runtime and register sandboxed APIs
+	runtime := NewExtensionRuntime(ext)
+	runtime.RegisterAPIs(vm)
+	runtime.RegisterGoBackendAPIs(vm)
+
+	// Set up console.log for debugging
+	console := vm.NewObject()
+	console.Set("log", func(call goja.FunctionCall) goja.Value {
+		args := make([]interface{}, len(call.Arguments))
+		for i, arg := range call.Arguments {
+			args[i] = arg.Export()
+		}
+		GoLog("[Extension:%s] %v\n", ext.ID, args)
+		return goja.Undefined()
+	})
+	vm.Set("console", console)
+
+	// Set up registerExtension function
+	var registeredExtension goja.Value
+	vm.Set("registerExtension", func(call goja.FunctionCall) goja.Value {
+		if len(call.Arguments) > 0 {
+			registeredExtension = call.Arguments[0]
+			// Also set it as global 'extension' variable for later access
+			vm.Set("extension", call.Arguments[0])
+		}
+		return goja.Undefined()
+	})
+
+	// Run the extension code
+	_, err = vm.RunString(string(jsCode))
+	if err != nil {
+		return fmt.Errorf("failed to execute extension code: %w", err)
+	}
+
+	// Verify extension was registered
+	if registeredExtension == nil || goja.IsUndefined(registeredExtension) {
+		return fmt.Errorf("extension did not call registerExtension()")
+	}
+
+	return nil
+}
+
+// UnloadExtension unloads an extension by ID
+func (m *ExtensionManager) UnloadExtension(extensionID string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	ext, exists := m.extensions[extensionID]
+	if !exists {
+		return fmt.Errorf("Extension not found")
+	}
+
+	// Call cleanup if VM is initialized
+	if ext.VM != nil {
+		// Try to call cleanup function
+		cleanup, err := ext.VM.RunString("typeof extension !== 'undefined' && typeof extension.cleanup === 'function' ? extension.cleanup() : null")
+		if err != nil {
+			GoLog("[Extension] Error calling cleanup for %s: %v\n", extensionID, err)
+		} else if cleanup != nil && !goja.IsUndefined(cleanup) && !goja.IsNull(cleanup) {
+			GoLog("[Extension] Cleanup called for %s\n", extensionID)
+		}
+	}
+
+	// Remove from registry
+	delete(m.extensions, extensionID)
+	GoLog("[Extension] Unloaded extension: %s\n", extensionID)
+
+	return nil
+}
+
+// GetExtension returns a loaded extension by ID
+// Returns error if extension not found (gomobile compatible)
+func (m *ExtensionManager) GetExtension(extensionID string) (*LoadedExtension, error) {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	ext, exists := m.extensions[extensionID]
+	if !exists {
+		return nil, fmt.Errorf("Extension not found")
+	}
+	return ext, nil
+}
+
+// GetAllExtensions returns all loaded extensions
+func (m *ExtensionManager) GetAllExtensions() []*LoadedExtension {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	result := make([]*LoadedExtension, 0, len(m.extensions))
+	for _, ext := range m.extensions {
+		result = append(result, ext)
+	}
+	return result
+}
+
+// SetExtensionEnabled enables or disables an extension
+func (m *ExtensionManager) SetExtensionEnabled(extensionID string, enabled bool) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	ext, exists := m.extensions[extensionID]
+	if !exists {
+		return fmt.Errorf("Extension not found")
+	}
+
+	ext.Enabled = enabled
+	GoLog("[Extension] %s %s\n", extensionID, map[bool]string{true: "enabled", false: "disabled"}[enabled])
+
+	// Persist enabled state to settings store
+	store := GetExtensionSettingsStore()
+	if err := store.Set(extensionID, "_enabled", enabled); err != nil {
+		GoLog("[Extension] Failed to persist enabled state for %s: %v\n", extensionID, err)
+	}
+
+	return nil
+}
+
+// LoadExtensionsFromDirectory scans a directory and loads all valid extensions
+func (m *ExtensionManager) LoadExtensionsFromDirectory(dirPath string) ([]string, []error) {
+	var loaded []string
+	var errors []error
+
+	entries, err := os.ReadDir(dirPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return loaded, errors
+		}
+		return nil, []error{fmt.Errorf("failed to read extensions directory: %w", err)}
+	}
+
+	for _, entry := range entries {
+		if entry.IsDir() {
+			// Check if it's an extracted extension directory
+			manifestPath := filepath.Join(dirPath, entry.Name(), "manifest.json")
+			if _, err := os.Stat(manifestPath); err == nil {
+				ext, err := m.loadExtensionFromDirectory(filepath.Join(dirPath, entry.Name()))
+				if err != nil {
+					GoLog("[Extension] Failed to load %s: %v\n", entry.Name(), err)
+					errors = append(errors, fmt.Errorf("%s: %w", entry.Name(), err))
+				} else {
+					loaded = append(loaded, ext.ID)
+				}
+			}
+		} else if strings.HasSuffix(strings.ToLower(entry.Name()), ".spotiflac-ext") {
+			// Load from package file
+			ext, err := m.LoadExtensionFromFile(filepath.Join(dirPath, entry.Name()))
+			if err != nil {
+				GoLog("[Extension] Failed to load %s: %v\n", entry.Name(), err)
+				errors = append(errors, fmt.Errorf("%s: %w", entry.Name(), err))
+			} else {
+				loaded = append(loaded, ext.ID)
+			}
+		}
+	}
+
+	return loaded, errors
+}
+
+// loadExtensionFromDirectory loads an extension from an already extracted directory
+func (m *ExtensionManager) loadExtensionFromDirectory(dirPath string) (*LoadedExtension, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	// Read manifest
+	manifestPath := filepath.Join(dirPath, "manifest.json")
+	manifestData, err := os.ReadFile(manifestPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read manifest.json: %w", err)
+	}
+
+	// Parse and validate manifest
+	manifest, err := ParseManifest(manifestData)
+	if err != nil {
+		return nil, fmt.Errorf("Invalid extension manifest: %w", err)
+	}
+
+	// Check if index.js exists
+	indexPath := filepath.Join(dirPath, "index.js")
+	if _, err := os.Stat(indexPath); os.IsNotExist(err) {
+		return nil, fmt.Errorf("Extension is missing index.js file")
+	}
+
+	// Check if extension already loaded - skip if already exists (for directory loading on startup)
+	if _, exists := m.extensions[manifest.Name]; exists {
+		return nil, fmt.Errorf("Extension '%s' is already loaded", manifest.DisplayName)
+	}
+
+	// Create data directory for extension
+	extDataDir := filepath.Join(m.dataDir, manifest.Name)
+	if err := os.MkdirAll(extDataDir, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create extension data directory: %w", err)
+	}
+
+	// Create loaded extension
+	ext := &LoadedExtension{
+		ID:        manifest.Name,
+		Manifest:  manifest,
+		Enabled:   true,
+		DataDir:   extDataDir,
+		SourceDir: dirPath,
+	}
+
+	// Restore enabled state from settings store
+	store := GetExtensionSettingsStore()
+	if enabledVal, err := store.Get(manifest.Name, "_enabled"); err == nil {
+		if enabled, ok := enabledVal.(bool); ok {
+			ext.Enabled = enabled
+			GoLog("[Extension] Restored enabled state for %s: %v\n", manifest.Name, enabled)
+		}
+	}
+
+	// Initialize Goja VM
+	if err := m.initializeVM(ext); err != nil {
+		ext.Error = err.Error()
+		ext.Enabled = false
+		GoLog("[Extension] Failed to initialize VM for %s: %v\n", manifest.Name, err)
+	}
+
+	m.extensions[manifest.Name] = ext
+	GoLog("[Extension] Loaded extension: %s v%s\n", manifest.DisplayName, manifest.Version)
+
+	return ext, nil
+}
+
+// RemoveExtension completely removes an extension (unload + delete files)
+func (m *ExtensionManager) RemoveExtension(extensionID string) error {
+	ext, err := m.GetExtension(extensionID)
+	if err != nil {
+		return err
+	}
+
+	// Unload first
+	if err := m.UnloadExtension(extensionID); err != nil {
+		return err
+	}
+
+	// Remove source directory
+	if ext.SourceDir != "" {
+		if err := os.RemoveAll(ext.SourceDir); err != nil {
+			GoLog("[Extension] Warning: failed to remove source dir: %v\n", err)
+		}
+	}
+
+	// Optionally remove data directory (keep for now to preserve settings)
+	// if ext.DataDir != "" {
+	//     os.RemoveAll(ext.DataDir)
+	// }
+
+	return nil
+}
+
+// UpgradeExtension upgrades an existing extension from a new package file
+// Only allows upgrades (new version > current version), not downgrades
+func (m *ExtensionManager) UpgradeExtension(filePath string) (*LoadedExtension, error) {
+	// Validate file extension
+	if !strings.HasSuffix(strings.ToLower(filePath), ".spotiflac-ext") {
+		return nil, fmt.Errorf("Invalid file format. Please select a .spotiflac-ext file")
+	}
+
+	// Open the zip file
+	zipReader, err := zip.OpenReader(filePath)
+	if err != nil {
+		return nil, fmt.Errorf("Cannot open extension file. The file may be corrupted or not a valid extension package")
+	}
+	defer zipReader.Close()
+
+	// Find and read manifest.json
+	var manifestData []byte
+	var hasIndexJS bool
+	for _, file := range zipReader.File {
+		name := filepath.Base(file.Name)
+		if name == "manifest.json" {
+			rc, err := file.Open()
+			if err != nil {
+				return nil, fmt.Errorf("failed to open manifest.json: %w", err)
+			}
+			manifestData, err = io.ReadAll(rc)
+			rc.Close()
+			if err != nil {
+				return nil, fmt.Errorf("failed to read manifest.json: %w", err)
+			}
+		}
+		if name == "index.js" {
+			hasIndexJS = true
+		}
+	}
+
+	if manifestData == nil {
+		return nil, fmt.Errorf("Invalid extension package: manifest.json not found")
+	}
+
+	if !hasIndexJS {
+		return nil, fmt.Errorf("Invalid extension package: index.js not found")
+	}
+
+	// Parse and validate manifest
+	newManifest, err := ParseManifest(manifestData)
+	if err != nil {
+		return nil, fmt.Errorf("Invalid extension manifest: %w", err)
+	}
+
+	// Check if extension exists
+	m.mu.RLock()
+	existing, exists := m.extensions[newManifest.Name]
+	m.mu.RUnlock()
+
+	if !exists {
+		return nil, fmt.Errorf("Extension '%s' is not installed. Use install instead of upgrade.", newManifest.DisplayName)
+	}
+
+	// Compare versions - only allow upgrade, not downgrade
+	versionCompare := compareVersions(newManifest.Version, existing.Manifest.Version)
+	if versionCompare < 0 {
+		return nil, fmt.Errorf("Cannot downgrade extension. Current version: %s, New version: %s", existing.Manifest.Version, newManifest.Version)
+	}
+	if versionCompare == 0 {
+		return nil, fmt.Errorf("Extension is already at version %s", existing.Manifest.Version)
+	}
+
+	GoLog("[Extension] Upgrading %s from v%s to v%s\n", newManifest.DisplayName, existing.Manifest.Version, newManifest.Version)
+
+	// Save data directory path (we want to preserve it)
+	extDataDir := existing.DataDir
+	extDir := existing.SourceDir
+
+	// Cleanup and unload existing extension
+	m.CleanupExtension(existing.ID)
+	m.UnloadExtension(existing.ID)
+
+	// Remove old source files but keep data directory
+	if extDir != "" {
+		if err := os.RemoveAll(extDir); err != nil {
+			GoLog("[Extension] Warning: failed to remove old source dir: %v\n", err)
+		}
+	}
+
+	// Recreate extension directory
+	if err := os.MkdirAll(extDir, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create extension directory: %w", err)
+	}
+
+	// Extract all files from new package
+	for _, file := range zipReader.File {
+		if file.FileInfo().IsDir() {
+			continue
+		}
+
+		// Get relative path within the zip
+		destPath := filepath.Join(extDir, filepath.Base(file.Name))
+
+		// Create destination file
+		destFile, err := os.Create(destPath)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create file %s: %w", destPath, err)
+		}
+
+		// Copy content
+		srcFile, err := file.Open()
+		if err != nil {
+			destFile.Close()
+			return nil, fmt.Errorf("failed to open file in archive: %w", err)
+		}
+
+		_, err = io.Copy(destFile, srcFile)
+		srcFile.Close()
+		destFile.Close()
+		if err != nil {
+			return nil, fmt.Errorf("failed to extract file: %w", err)
+		}
+	}
+
+	// Create new loaded extension (reusing data directory)
+	ext := &LoadedExtension{
+		ID:        newManifest.Name,
+		Manifest:  newManifest,
+		Enabled:   true,
+		DataDir:   extDataDir,
+		SourceDir: extDir,
+	}
+
+	// Initialize Goja VM
+	if err := m.initializeVM(ext); err != nil {
+		ext.Error = err.Error()
+		ext.Enabled = false
+		GoLog("[Extension] Failed to initialize VM for %s: %v\n", newManifest.Name, err)
+	}
+
+	m.mu.Lock()
+	m.extensions[newManifest.Name] = ext
+	m.mu.Unlock()
+
+	GoLog("[Extension] Upgraded extension: %s to v%s\n", newManifest.DisplayName, newManifest.Version)
+
+	return ext, nil
+}
+
+// ExtensionUpgradeInfo holds information about extension upgrade check
+type ExtensionUpgradeInfo struct {
+	ExtensionID    string `json:"extension_id"`
+	CurrentVersion string `json:"current_version"`
+	NewVersion     string `json:"new_version"`
+	CanUpgrade     bool   `json:"can_upgrade"`
+	IsInstalled    bool   `json:"is_installed"`
+}
+
+// checkExtensionUpgradeInternal checks if a package file is an upgrade for an existing extension
+// Internal function that returns struct
+func (m *ExtensionManager) checkExtensionUpgradeInternal(filePath string) (*ExtensionUpgradeInfo, error) {
+	// Validate file extension
+	if !strings.HasSuffix(strings.ToLower(filePath), ".spotiflac-ext") {
+		return nil, fmt.Errorf("Invalid file format")
+	}
+
+	// Open the zip file
+	zipReader, err := zip.OpenReader(filePath)
+	if err != nil {
+		return nil, fmt.Errorf("Cannot open extension file")
+	}
+	defer zipReader.Close()
+
+	// Find and read manifest.json
+	var manifestData []byte
+	for _, file := range zipReader.File {
+		name := filepath.Base(file.Name)
+		if name == "manifest.json" {
+			rc, err := file.Open()
+			if err != nil {
+				return nil, fmt.Errorf("failed to open manifest.json")
+			}
+			manifestData, err = io.ReadAll(rc)
+			rc.Close()
+			if err != nil {
+				return nil, fmt.Errorf("failed to read manifest.json")
+			}
+			break
+		}
+	}
+
+	if manifestData == nil {
+		return nil, fmt.Errorf("manifest.json not found")
+	}
+
+	// Parse manifest
+	newManifest, err := ParseManifest(manifestData)
+	if err != nil {
+		return nil, fmt.Errorf("Invalid manifest: %w", err)
+	}
+
+	// Check if extension exists
+	m.mu.RLock()
+	existing, exists := m.extensions[newManifest.Name]
+	m.mu.RUnlock()
+
+	info := &ExtensionUpgradeInfo{
+		ExtensionID: newManifest.Name,
+		NewVersion:  newManifest.Version,
+		IsInstalled: exists,
+	}
+
+	if !exists {
+		// Not installed - this is a new install, not upgrade
+		info.CurrentVersion = ""
+		info.CanUpgrade = false
+	} else {
+		// Compare versions
+		info.CurrentVersion = existing.Manifest.Version
+		info.CanUpgrade = compareVersions(newManifest.Version, existing.Manifest.Version) > 0
+	}
+
+	return info, nil
+}
+
+// CheckExtensionUpgradeJSON checks if a package file is an upgrade and returns JSON
+func (m *ExtensionManager) CheckExtensionUpgradeJSON(filePath string) (string, error) {
+	info, err := m.checkExtensionUpgradeInternal(filePath)
+	if err != nil {
+		return "", err
+	}
+
+	jsonBytes, err := json.Marshal(info)
+	if err != nil {
+		return "", err
+	}
+
+	return string(jsonBytes), nil
+}
+
+// GetInstalledExtensionsJSON returns all extensions as JSON for Flutter
+func (m *ExtensionManager) GetInstalledExtensionsJSON() (string, error) {
+	extensions := m.GetAllExtensions()
+
+	type ExtensionInfo struct {
+		ID                     string                `json:"id"`
+		Name                   string                `json:"name"`
+		DisplayName            string                `json:"display_name"`
+		Version                string                `json:"version"`
+		Author                 string                `json:"author"`
+		Description            string                `json:"description"`
+		Homepage               string                `json:"homepage,omitempty"`
+		IconPath               string                `json:"icon_path,omitempty"`
+		Types                  []ExtensionType       `json:"types"`
+		Enabled                bool                  `json:"enabled"`
+		Status                 string                `json:"status"`
+		Error                  string                `json:"error_message,omitempty"`
+		Settings               []ExtensionSetting    `json:"settings,omitempty"`
+		QualityOptions         []QualityOption       `json:"quality_options,omitempty"`
+		Permissions            []string              `json:"permissions"`
+		HasMetadataProvider    bool                  `json:"has_metadata_provider"`
+		HasDownloadProvider    bool                  `json:"has_download_provider"`
+		SkipMetadataEnrichment bool                  `json:"skip_metadata_enrichment"`
+		SearchBehavior         *SearchBehaviorConfig `json:"search_behavior,omitempty"`
+		TrackMatching          *TrackMatchingConfig  `json:"track_matching,omitempty"`
+		PostProcessing         *PostProcessingConfig `json:"post_processing,omitempty"`
+	}
+
+	infos := make([]ExtensionInfo, len(extensions))
+	for i, ext := range extensions {
+		// Build permissions list
+		permissions := []string{}
+		for _, domain := range ext.Manifest.Permissions.Network {
+			permissions = append(permissions, "network:"+domain)
+		}
+		if ext.Manifest.Permissions.Storage {
+			permissions = append(permissions, "storage:enabled")
+		}
+
+		// Determine status
+		status := "loaded"
+		if ext.Error != "" {
+			status = "error"
+		} else if !ext.Enabled {
+			status = "disabled"
+		}
+
+		// Check for icon file
+		iconPath := ""
+		if ext.Manifest.Icon != "" && ext.SourceDir != "" {
+			possibleIcon := filepath.Join(ext.SourceDir, ext.Manifest.Icon)
+			if _, err := os.Stat(possibleIcon); err == nil {
+				iconPath = possibleIcon
+			}
+		}
+		// Fallback: check for icon.png if not specified in manifest
+		if iconPath == "" && ext.SourceDir != "" {
+			possibleIcon := filepath.Join(ext.SourceDir, "icon.png")
+			if _, err := os.Stat(possibleIcon); err == nil {
+				iconPath = possibleIcon
+			}
+		}
+
+		infos[i] = ExtensionInfo{
+			ID:                     ext.ID,
+			Name:                   ext.Manifest.Name,
+			DisplayName:            ext.Manifest.DisplayName,
+			Version:                ext.Manifest.Version,
+			Author:                 ext.Manifest.Author,
+			Description:            ext.Manifest.Description,
+			Homepage:               ext.Manifest.Homepage,
+			IconPath:               iconPath,
+			Types:                  ext.Manifest.Types,
+			Enabled:                ext.Enabled,
+			Status:                 status,
+			Error:                  ext.Error,
+			Settings:               ext.Manifest.Settings,
+			QualityOptions:         ext.Manifest.QualityOptions,
+			Permissions:            permissions,
+			HasMetadataProvider:    ext.Manifest.IsMetadataProvider(),
+			HasDownloadProvider:    ext.Manifest.IsDownloadProvider(),
+			SkipMetadataEnrichment: ext.Manifest.SkipMetadataEnrichment,
+			SearchBehavior:         ext.Manifest.SearchBehavior,
+			TrackMatching:          ext.Manifest.TrackMatching,
+			PostProcessing:         ext.Manifest.PostProcessing,
+		}
+	}
+
+	jsonBytes, err := json.Marshal(infos)
+	if err != nil {
+		return "", err
+	}
+
+	return string(jsonBytes), nil
+}
+
+// ==================== Extension Lifecycle ====================
+
+// InitializeExtension calls the extension's initialize method with settings
+func (m *ExtensionManager) InitializeExtension(extensionID string, settings map[string]interface{}) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	ext, exists := m.extensions[extensionID]
+	if !exists {
+		return fmt.Errorf("Extension not found")
+	}
+
+	if ext.VM == nil {
+		return fmt.Errorf("Extension failed to load. Please reinstall the extension")
+	}
+
+	// Convert settings to JSON for passing to JS
+	settingsJSON, err := json.Marshal(settings)
+	if err != nil {
+		return fmt.Errorf("Failed to save settings")
+	}
+
+	// Call initialize function
+	script := fmt.Sprintf(`
+		(function() {
+			var settings = %s;
+			if (typeof extension !== 'undefined' && typeof extension.initialize === 'function') {
+				try {
+					extension.initialize(settings);
+					return { success: true };
+				} catch (e) {
+					return { success: false, error: e.toString() };
+				}
+			}
+			return { success: true, message: 'no initialize function' };
+		})()
+	`, string(settingsJSON))
+
+	result, err := ext.VM.RunString(script)
+	if err != nil {
+		ext.Error = fmt.Sprintf("initialize failed: %v", err)
+		ext.Enabled = false
+		GoLog("[Extension] Initialize error for %s: %v\n", extensionID, err)
+		return err
+	}
+
+	// Check result
+	if result != nil && !goja.IsUndefined(result) {
+		exported := result.Export()
+		if resultMap, ok := exported.(map[string]interface{}); ok {
+			if success, ok := resultMap["success"].(bool); ok && !success {
+				errMsg := "unknown error"
+				if e, ok := resultMap["error"].(string); ok {
+					errMsg = e
+				}
+				ext.Error = errMsg
+				ext.Enabled = false
+				GoLog("[Extension] Initialize failed for %s: %s\n", extensionID, errMsg)
+				return fmt.Errorf("initialize failed: %s", errMsg)
+			}
+		}
+	}
+
+	GoLog("[Extension] Initialized %s\n", extensionID)
+	return nil
+}
+
+// CleanupExtension calls the extension's cleanup method
+func (m *ExtensionManager) CleanupExtension(extensionID string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	ext, exists := m.extensions[extensionID]
+	if !exists {
+		return fmt.Errorf("Extension not found")
+	}
+
+	if ext.VM == nil {
+		return nil // No VM, nothing to cleanup
+	}
+
+	// Call cleanup function
+	script := `
+		(function() {
+			if (typeof extension !== 'undefined' && typeof extension.cleanup === 'function') {
+				try {
+					extension.cleanup();
+					return { success: true };
+				} catch (e) {
+					return { success: false, error: e.toString() };
+				}
+			}
+			return { success: true, message: 'no cleanup function' };
+		})()
+	`
+
+	result, err := ext.VM.RunString(script)
+	if err != nil {
+		GoLog("[Extension] Cleanup error for %s: %v\n", extensionID, err)
+		return err
+	}
+
+	// Check result
+	if result != nil && !goja.IsUndefined(result) {
+		exported := result.Export()
+		if resultMap, ok := exported.(map[string]interface{}); ok {
+			if success, ok := resultMap["success"].(bool); ok && !success {
+				errMsg := "unknown error"
+				if e, ok := resultMap["error"].(string); ok {
+					errMsg = e
+				}
+				GoLog("[Extension] Cleanup failed for %s: %s\n", extensionID, errMsg)
+				return fmt.Errorf("cleanup failed: %s", errMsg)
+			}
+		}
+	}
+
+	GoLog("[Extension] Cleaned up %s\n", extensionID)
+	return nil
+}
+
+// UnloadAllExtensions unloads all extensions gracefully
+func (m *ExtensionManager) UnloadAllExtensions() {
+	m.mu.Lock()
+	extensionIDs := make([]string, 0, len(m.extensions))
+	for id := range m.extensions {
+		extensionIDs = append(extensionIDs, id)
+	}
+	m.mu.Unlock()
+
+	for _, id := range extensionIDs {
+		// Call cleanup first
+		m.CleanupExtension(id)
+		// Then unload
+		m.UnloadExtension(id)
+	}
+
+	GoLog("[Extension] All extensions unloaded\n")
+}

go_backend/extension_manifest.go

@@ -0,0 +1,284 @@
+// Package gobackend provides extension manifest parsing and validation
+package gobackend
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+// ExtensionType represents the type of extension
+type ExtensionType string
+
+const (
+	ExtensionTypeMetadataProvider ExtensionType = "metadata_provider"
+	ExtensionTypeDownloadProvider ExtensionType = "download_provider"
+)
+
+// SettingType represents the type of a setting field
+type SettingType string
+
+const (
+	SettingTypeString SettingType = "string"
+	SettingTypeNumber SettingType = "number"
+	SettingTypeBool   SettingType = "boolean"
+	SettingTypeSelect SettingType = "select"
+)
+
+// ExtensionPermissions defines what resources an extension can access
+type ExtensionPermissions struct {
+	Network []string `json:"network"` // List of allowed domains
+	Storage bool     `json:"storage"` // Whether extension can use storage API
+}
+
+// ExtensionSetting defines a configurable setting for an extension
+type ExtensionSetting struct {
+	Key         string      `json:"key"`
+	Type        SettingType `json:"type"`
+	Label       string      `json:"label"`
+	Description string      `json:"description,omitempty"`
+	Required    bool        `json:"required,omitempty"`
+	Secret      bool        `json:"secret,omitempty"`
+	Default     interface{} `json:"default,omitempty"`
+	Options     []string    `json:"options,omitempty"` // For select type
+}
+
+// QualityOption represents a quality option for download providers
+type QualityOption struct {
+	ID          string                   `json:"id"`                 // Unique identifier (e.g., "mp3_320", "opus_128")
+	Label       string                   `json:"label"`              // Display name (e.g., "MP3 320kbps")
+	Description string                   `json:"description"`        // Optional description (e.g., "Best quality MP3")
+	Settings    []QualitySpecificSetting `json:"settings,omitempty"` // Quality-specific settings
+}
+
+// QualitySpecificSetting represents a setting that's specific to a quality option
+type QualitySpecificSetting struct {
+	Key         string      `json:"key"`
+	Type        SettingType `json:"type"`
+	Label       string      `json:"label"`
+	Description string      `json:"description,omitempty"`
+	Required    bool        `json:"required,omitempty"`
+	Secret      bool        `json:"secret,omitempty"`
+	Default     interface{} `json:"default,omitempty"`
+	Options     []string    `json:"options,omitempty"` // For select type
+}
+
+// SearchBehaviorConfig defines custom search behavior for an extension
+type SearchBehaviorConfig struct {
+	Enabled         bool   `json:"enabled"`                   // Whether extension provides custom search
+	Placeholder     string `json:"placeholder,omitempty"`     // Placeholder text for search box
+	Primary         bool   `json:"primary,omitempty"`         // If true, show as primary search tab
+	Icon            string `json:"icon,omitempty"`            // Icon for search tab
+	ThumbnailRatio  string `json:"thumbnailRatio,omitempty"`  // Thumbnail aspect ratio: "square" (1:1), "wide" (16:9), "portrait" (2:3)
+	ThumbnailWidth  int    `json:"thumbnailWidth,omitempty"`  // Custom thumbnail width in pixels
+	ThumbnailHeight int    `json:"thumbnailHeight,omitempty"` // Custom thumbnail height in pixels
+}
+
+// TrackMatchingConfig defines custom track matching behavior
+type TrackMatchingConfig struct {
+	CustomMatching    bool   `json:"customMatching"`              // Whether extension handles matching
+	Strategy          string `json:"strategy,omitempty"`          // "isrc", "name", "duration", "custom"
+	DurationTolerance int    `json:"durationTolerance,omitempty"` // Tolerance in seconds for duration matching
+}
+
+// PostProcessingHook defines a post-processing hook
+type PostProcessingHook struct {
+	ID               string   `json:"id"`                         // Unique identifier
+	Name             string   `json:"name"`                       // Display name
+	Description      string   `json:"description,omitempty"`      // Description
+	DefaultEnabled   bool     `json:"defaultEnabled,omitempty"`   // Whether enabled by default
+	SupportedFormats []string `json:"supportedFormats,omitempty"` // Supported file formats (e.g., ["flac", "mp3"])
+}
+
+// PostProcessingConfig defines post-processing capabilities
+type PostProcessingConfig struct {
+	Enabled bool                 `json:"enabled"`         // Whether extension provides post-processing
+	Hooks   []PostProcessingHook `json:"hooks,omitempty"` // Available hooks
+}
+
+// ExtensionManifest represents the manifest.json of an extension
+type ExtensionManifest struct {
+	Name                   string                `json:"name"`
+	DisplayName            string                `json:"displayName"`
+	Version                string                `json:"version"`
+	Author                 string                `json:"author"`
+	Description            string                `json:"description"`
+	Homepage               string                `json:"homepage,omitempty"`
+	Icon                   string                `json:"icon,omitempty"` // Icon filename (e.g., "icon.png")
+	Types                  []ExtensionType       `json:"type"`
+	Permissions            ExtensionPermissions  `json:"permissions"`
+	Settings               []ExtensionSetting    `json:"settings,omitempty"`
+	QualityOptions         []QualityOption       `json:"qualityOptions,omitempty"` // Custom quality options for download providers
+	MinAppVersion          string                `json:"minAppVersion,omitempty"`
+	SkipMetadataEnrichment bool                  `json:"skipMetadataEnrichment,omitempty"` // If true, don't enrich metadata from Deezer/Spotify
+	SkipBuiltInFallback    bool                  `json:"skipBuiltInFallback,omitempty"`    // If true, don't fallback to built-in providers (tidal/qobuz/amazon)
+	SearchBehavior         *SearchBehaviorConfig `json:"searchBehavior,omitempty"`         // Custom search behavior
+	TrackMatching          *TrackMatchingConfig  `json:"trackMatching,omitempty"`          // Custom track matching
+	PostProcessing         *PostProcessingConfig `json:"postProcessing,omitempty"`         // Post-processing hooks
+}
+
+// ManifestValidationError represents a validation error in the manifest
+type ManifestValidationError struct {
+	Field   string
+	Message string
+}
+
+func (e *ManifestValidationError) Error() string {
+	return fmt.Sprintf("manifest validation error: %s - %s", e.Field, e.Message)
+}
+
+// ParseManifest parses and validates a manifest from JSON bytes
+func ParseManifest(data []byte) (*ExtensionManifest, error) {
+	var manifest ExtensionManifest
+	if err := json.Unmarshal(data, &manifest); err != nil {
+		return nil, fmt.Errorf("failed to parse manifest JSON: %w", err)
+	}
+
+	if err := manifest.Validate(); err != nil {
+		return nil, err
+	}
+
+	return &manifest, nil
+}
+
+// Validate checks if the manifest has all required fields and valid values
+func (m *ExtensionManifest) Validate() error {
+	// Check required fields
+	if strings.TrimSpace(m.Name) == "" {
+		return &ManifestValidationError{Field: "name", Message: "name is required"}
+	}
+
+	if strings.TrimSpace(m.Version) == "" {
+		return &ManifestValidationError{Field: "version", Message: "version is required"}
+	}
+
+	if strings.TrimSpace(m.Author) == "" {
+		return &ManifestValidationError{Field: "author", Message: "author is required"}
+	}
+
+	if strings.TrimSpace(m.Description) == "" {
+		return &ManifestValidationError{Field: "description", Message: "description is required"}
+	}
+
+	if len(m.Types) == 0 {
+		return &ManifestValidationError{Field: "type", Message: "at least one type is required"}
+	}
+
+	// Validate extension types
+	for _, t := range m.Types {
+		if t != ExtensionTypeMetadataProvider && t != ExtensionTypeDownloadProvider {
+			return &ManifestValidationError{
+				Field:   "type",
+				Message: fmt.Sprintf("invalid extension type: %s (must be 'metadata_provider' or 'download_provider')", t),
+			}
+		}
+	}
+
+	// Validate settings if present
+	for i, setting := range m.Settings {
+		if strings.TrimSpace(setting.Key) == "" {
+			return &ManifestValidationError{
+				Field:   fmt.Sprintf("settings[%d].key", i),
+				Message: "setting key is required",
+			}
+		}
+
+		if setting.Type == "" {
+			return &ManifestValidationError{
+				Field:   fmt.Sprintf("settings[%d].type", i),
+				Message: "setting type is required",
+			}
+		}
+
+		// Validate setting type
+		validTypes := map[SettingType]bool{
+			SettingTypeString: true,
+			SettingTypeNumber: true,
+			SettingTypeBool:   true,
+			SettingTypeSelect: true,
+		}
+		if !validTypes[setting.Type] {
+			return &ManifestValidationError{
+				Field:   fmt.Sprintf("settings[%d].type", i),
+				Message: fmt.Sprintf("invalid setting type: %s", setting.Type),
+			}
+		}
+
+		// Select type requires options
+		if setting.Type == SettingTypeSelect && len(setting.Options) == 0 {
+			return &ManifestValidationError{
+				Field:   fmt.Sprintf("settings[%d].options", i),
+				Message: "select type requires options",
+			}
+		}
+	}
+
+	return nil
+}
+
+// HasType checks if the extension has a specific type
+func (m *ExtensionManifest) HasType(t ExtensionType) bool {
+	for _, et := range m.Types {
+		if et == t {
+			return true
+		}
+	}
+	return false
+}
+
+// IsMetadataProvider returns true if extension provides metadata
+func (m *ExtensionManifest) IsMetadataProvider() bool {
+	return m.HasType(ExtensionTypeMetadataProvider)
+}
+
+// IsDownloadProvider returns true if extension provides downloads
+func (m *ExtensionManifest) IsDownloadProvider() bool {
+	return m.HasType(ExtensionTypeDownloadProvider)
+}
+
+// IsDomainAllowed checks if a domain is in the allowed network permissions
+func (m *ExtensionManifest) IsDomainAllowed(domain string) bool {
+	domain = strings.ToLower(strings.TrimSpace(domain))
+	for _, allowed := range m.Permissions.Network {
+		allowed = strings.ToLower(strings.TrimSpace(allowed))
+		if allowed == domain {
+			return true
+		}
+		// Support wildcard subdomains (e.g., *.example.com)
+		if strings.HasPrefix(allowed, "*.") {
+			suffix := allowed[1:] // Remove the *
+			if strings.HasSuffix(domain, suffix) {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+// HasCustomSearch returns true if extension provides custom search
+func (m *ExtensionManifest) HasCustomSearch() bool {
+	return m.SearchBehavior != nil && m.SearchBehavior.Enabled
+}
+
+// HasCustomMatching returns true if extension provides custom track matching
+func (m *ExtensionManifest) HasCustomMatching() bool {
+	return m.TrackMatching != nil && m.TrackMatching.CustomMatching
+}
+
+// HasPostProcessing returns true if extension provides post-processing
+func (m *ExtensionManifest) HasPostProcessing() bool {
+	return m.PostProcessing != nil && m.PostProcessing.Enabled
+}
+
+// GetPostProcessingHooks returns all post-processing hooks
+func (m *ExtensionManifest) GetPostProcessingHooks() []PostProcessingHook {
+	if m.PostProcessing == nil {
+		return nil
+	}
+	return m.PostProcessing.Hooks
+}
+
+// ToJSON serializes the manifest to JSON
+func (m *ExtensionManifest) ToJSON() ([]byte, error) {
+	return json.Marshal(m)
+}

go_backend/extension_settings.go

@@ -0,0 +1,221 @@
+// Package gobackend provides extension settings storage
+package gobackend
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+)
+
+// ExtensionSettingsStore manages settings for all extensions
+type ExtensionSettingsStore struct {
+	mu       sync.RWMutex
+	dataDir  string
+	settings map[string]map[string]interface{} // extensionID -> settings
+}
+
+// Global settings store
+var (
+	globalSettingsStore     *ExtensionSettingsStore
+	globalSettingsStoreOnce sync.Once
+)
+
+// GetExtensionSettingsStore returns the global settings store
+func GetExtensionSettingsStore() *ExtensionSettingsStore {
+	globalSettingsStoreOnce.Do(func() {
+		globalSettingsStore = &ExtensionSettingsStore{
+			settings: make(map[string]map[string]interface{}),
+		}
+	})
+	return globalSettingsStore
+}
+
+// SetDataDir sets the data directory for settings storage
+func (s *ExtensionSettingsStore) SetDataDir(dataDir string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.dataDir = dataDir
+	if err := os.MkdirAll(dataDir, 0755); err != nil {
+		return fmt.Errorf("failed to create settings directory: %w", err)
+	}
+
+	// Load all existing settings
+	return s.loadAllSettings()
+}
+
+// getSettingsPath returns the path to an extension's settings file
+func (s *ExtensionSettingsStore) getSettingsPath(extensionID string) string {
+	return filepath.Join(s.dataDir, extensionID, "settings.json")
+}
+
+// loadAllSettings loads settings for all extensions from disk
+func (s *ExtensionSettingsStore) loadAllSettings() error {
+	entries, err := os.ReadDir(s.dataDir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+
+	for _, entry := range entries {
+		if entry.IsDir() {
+			extensionID := entry.Name()
+			settings, err := s.loadSettings(extensionID)
+			if err != nil {
+				GoLog("[ExtensionSettings] Failed to load settings for %s: %v\n", extensionID, err)
+				continue
+			}
+			s.settings[extensionID] = settings
+		}
+	}
+
+	return nil
+}
+
+// loadSettings loads settings for a specific extension
+func (s *ExtensionSettingsStore) loadSettings(extensionID string) (map[string]interface{}, error) {
+	settingsPath := s.getSettingsPath(extensionID)
+	data, err := os.ReadFile(settingsPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return make(map[string]interface{}), nil
+		}
+		return nil, err
+	}
+
+	var settings map[string]interface{}
+	if err := json.Unmarshal(data, &settings); err != nil {
+		return nil, err
+	}
+
+	return settings, nil
+}
+
+// saveSettings saves settings for a specific extension
+func (s *ExtensionSettingsStore) saveSettings(extensionID string, settings map[string]interface{}) error {
+	settingsPath := s.getSettingsPath(extensionID)
+
+	// Create directory if needed
+	dir := filepath.Dir(settingsPath)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return err
+	}
+
+	data, err := json.MarshalIndent(settings, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	return os.WriteFile(settingsPath, data, 0644)
+}
+
+// Get retrieves a setting value for an extension
+// Returns error if extension or key not found (gomobile compatible)
+func (s *ExtensionSettingsStore) Get(extensionID, key string) (interface{}, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	extSettings, exists := s.settings[extensionID]
+	if !exists {
+		return nil, fmt.Errorf("extension '%s' settings not found", extensionID)
+	}
+
+	value, exists := extSettings[key]
+	if !exists {
+		return nil, fmt.Errorf("setting '%s' not found for extension '%s'", key, extensionID)
+	}
+	return value, nil
+}
+
+// GetAll retrieves all settings for an extension
+func (s *ExtensionSettingsStore) GetAll(extensionID string) map[string]interface{} {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	extSettings, exists := s.settings[extensionID]
+	if !exists {
+		return make(map[string]interface{})
+	}
+
+	// Return a copy
+	result := make(map[string]interface{})
+	for k, v := range extSettings {
+		result[k] = v
+	}
+	return result
+}
+
+// Set stores a setting value for an extension
+func (s *ExtensionSettingsStore) Set(extensionID, key string, value interface{}) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if _, exists := s.settings[extensionID]; !exists {
+		s.settings[extensionID] = make(map[string]interface{})
+	}
+
+	s.settings[extensionID][key] = value
+
+	// Persist to disk
+	return s.saveSettings(extensionID, s.settings[extensionID])
+}
+
+// SetAll stores all settings for an extension
+func (s *ExtensionSettingsStore) SetAll(extensionID string, settings map[string]interface{}) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.settings[extensionID] = settings
+
+	// Persist to disk
+	return s.saveSettings(extensionID, settings)
+}
+
+// Remove removes a setting for an extension
+func (s *ExtensionSettingsStore) Remove(extensionID, key string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	extSettings, exists := s.settings[extensionID]
+	if !exists {
+		return nil
+	}
+
+	delete(extSettings, key)
+
+	// Persist to disk
+	return s.saveSettings(extensionID, extSettings)
+}
+
+// RemoveAll removes all settings for an extension
+func (s *ExtensionSettingsStore) RemoveAll(extensionID string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	delete(s.settings, extensionID)
+
+	// Remove settings file
+	settingsPath := s.getSettingsPath(extensionID)
+	if err := os.Remove(settingsPath); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+
+	return nil
+}
+
+// GetAllExtensionSettings returns settings for all extensions as JSON
+func (s *ExtensionSettingsStore) GetAllExtensionSettingsJSON() (string, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	data, err := json.Marshal(s.settings)
+	if err != nil {
+		return "", err
+	}
+
+	return string(data), nil
+}

go_backend/extension_test.go

@@ -0,0 +1,219 @@
+package gobackend
+
+import (
+	"testing"
+
+	"github.com/dop251/goja"
+)
+
+func TestParseManifest_Valid(t *testing.T) {
+	validManifest := `{
+		"name": "test-provider",
+		"displayName": "Test Provider",
+		"version": "1.0.0",
+		"author": "Test Author",
+		"description": "A test extension",
+		"type": ["metadata_provider"],
+		"permissions": {
+			"network": ["api.test.com"],
+			"storage": true
+		}
+	}`
+
+	manifest, err := ParseManifest([]byte(validManifest))
+	if err != nil {
+		t.Fatalf("Expected valid manifest to parse, got error: %v", err)
+	}
+
+	if manifest.Name != "test-provider" {
+		t.Errorf("Expected name 'test-provider', got '%s'", manifest.Name)
+	}
+
+	if manifest.Version != "1.0.0" {
+		t.Errorf("Expected version '1.0.0', got '%s'", manifest.Version)
+	}
+
+	if !manifest.IsMetadataProvider() {
+		t.Error("Expected IsMetadataProvider() to return true")
+	}
+
+	if manifest.IsDownloadProvider() {
+		t.Error("Expected IsDownloadProvider() to return false")
+	}
+}
+
+func TestParseManifest_MissingName(t *testing.T) {
+	invalidManifest := `{
+		"version": "1.0.0",
+		"author": "Test Author",
+		"description": "A test extension",
+		"type": ["metadata_provider"]
+	}`
+
+	_, err := ParseManifest([]byte(invalidManifest))
+	if err == nil {
+		t.Fatal("Expected error for missing name")
+	}
+}
+
+func TestParseManifest_MissingType(t *testing.T) {
+	invalidManifest := `{
+		"name": "test-provider",
+		"version": "1.0.0",
+		"author": "Test Author",
+		"description": "A test extension"
+	}`
+
+	_, err := ParseManifest([]byte(invalidManifest))
+	if err == nil {
+		t.Fatal("Expected error for missing type")
+	}
+}
+
+func TestIsDomainAllowed(t *testing.T) {
+	manifest := &ExtensionManifest{
+		Permissions: ExtensionPermissions{
+			Network: []string{"api.test.com", "*.example.com"},
+		},
+	}
+
+	tests := []struct {
+		domain   string
+		expected bool
+	}{
+		{"api.test.com", true},
+		{"api.example.com", true},
+		{"sub.example.com", true},
+		{"notallowed.com", false},
+		{"test.com", false},
+	}
+
+	for _, tt := range tests {
+		result := manifest.IsDomainAllowed(tt.domain)
+		if result != tt.expected {
+			t.Errorf("IsDomainAllowed(%s) = %v, expected %v", tt.domain, result, tt.expected)
+		}
+	}
+}
+
+func TestExtensionRuntime_NetworkSandbox(t *testing.T) {
+	// Create a mock extension with limited network permissions
+	ext := &LoadedExtension{
+		ID: "test-ext",
+		Manifest: &ExtensionManifest{
+			Name: "test-ext",
+			Permissions: ExtensionPermissions{
+				Network: []string{"api.allowed.com", "*.wildcard.com"},
+			},
+		},
+		DataDir: t.TempDir(),
+	}
+
+	runtime := NewExtensionRuntime(ext)
+
+	// Test allowed domains
+	if err := runtime.validateDomain("https://api.allowed.com/path"); err != nil {
+		t.Errorf("Expected api.allowed.com to be allowed, got error: %v", err)
+	}
+
+	if err := runtime.validateDomain("https://sub.wildcard.com/path"); err != nil {
+		t.Errorf("Expected sub.wildcard.com to be allowed (wildcard), got error: %v", err)
+	}
+
+	// Test blocked domains
+	if err := runtime.validateDomain("https://blocked.com/path"); err == nil {
+		t.Error("Expected blocked.com to be denied")
+	}
+
+	if err := runtime.validateDomain("https://notallowed.com/path"); err == nil {
+		t.Error("Expected notallowed.com to be denied")
+	}
+}
+
+func TestExtensionRuntime_FileSandbox(t *testing.T) {
+	tempDir := t.TempDir()
+
+	ext := &LoadedExtension{
+		ID: "test-ext",
+		Manifest: &ExtensionManifest{
+			Name: "test-ext",
+		},
+		DataDir: tempDir,
+	}
+
+	runtime := NewExtensionRuntime(ext)
+
+	// Test valid path within sandbox
+	validPath, err := runtime.validatePath("test.txt")
+	if err != nil {
+		t.Errorf("Expected relative path to be valid, got error: %v", err)
+	}
+	if validPath == "" {
+		t.Error("Expected non-empty path")
+	}
+
+	// Test path traversal attack
+	_, err = runtime.validatePath("../../../etc/passwd")
+	if err == nil {
+		t.Error("Expected path traversal to be blocked")
+	}
+
+	// Test nested path within sandbox (should be allowed)
+	nestedPath, err := runtime.validatePath("subdir/file.txt")
+	if err != nil {
+		t.Errorf("Expected nested path to be valid, got error: %v", err)
+	}
+	if nestedPath == "" {
+		t.Error("Expected non-empty nested path")
+	}
+}
+
+func TestExtensionRuntime_UtilityFunctions(t *testing.T) {
+	ext := &LoadedExtension{
+		ID: "test-ext",
+		Manifest: &ExtensionManifest{
+			Name: "test-ext",
+		},
+		DataDir: t.TempDir(),
+	}
+
+	runtime := NewExtensionRuntime(ext)
+	vm := goja.New()
+	runtime.RegisterAPIs(vm)
+
+	// Test base64 encode/decode
+	result, err := vm.RunString(`utils.base64Encode("hello")`)
+	if err != nil {
+		t.Fatalf("base64Encode failed: %v", err)
+	}
+	if result.String() != "aGVsbG8=" {
+		t.Errorf("Expected 'aGVsbG8=', got '%s'", result.String())
+	}
+
+	result, err = vm.RunString(`utils.base64Decode("aGVsbG8=")`)
+	if err != nil {
+		t.Fatalf("base64Decode failed: %v", err)
+	}
+	if result.String() != "hello" {
+		t.Errorf("Expected 'hello', got '%s'", result.String())
+	}
+
+	// Test MD5
+	result, err = vm.RunString(`utils.md5("hello")`)
+	if err != nil {
+		t.Fatalf("md5 failed: %v", err)
+	}
+	if result.String() != "5d41402abc4b2a76b9719d911017c592" {
+		t.Errorf("Expected '5d41402abc4b2a76b9719d911017c592', got '%s'", result.String())
+	}
+
+	// Test JSON parse/stringify
+	result, err = vm.RunString(`utils.stringifyJSON({name: "test", value: 123})`)
+	if err != nil {
+		t.Fatalf("stringifyJSON failed: %v", err)
+	}
+	// JSON output may vary in order, just check it's valid
+	if result.String() == "" {
+		t.Error("Expected non-empty JSON string")
+	}
+}

go_backend/go.mod

@@ -5,14 +5,19 @@ go 1.24.0
 toolchain go1.24.5
 
 require (
+	github.com/dop251/goja v0.0.0-20260106131823-651366fbe6e3
 	github.com/go-flac/flacpicture v0.3.0
 	github.com/go-flac/flacvorbis v0.2.0
 	github.com/go-flac/go-flac v1.0.0
 )
 
 require (
+	github.com/dlclark/regexp2 v1.11.4 // indirect
+	github.com/go-sourcemap/sourcemap v2.1.3+incompatible // indirect
+	github.com/google/pprof v0.0.0-20230207041349-798e818bf904 // indirect
 	golang.org/x/mobile v0.0.0-20251209145715-2553ed8ce294 // indirect
 	golang.org/x/mod v0.31.0 // indirect
 	golang.org/x/sync v0.19.0 // indirect
+	golang.org/x/text v0.3.8 // indirect
 	golang.org/x/tools v0.40.0 // indirect
 )

go_backend/go.sum

@@ -1,14 +1,28 @@
+github.com/Masterminds/semver/v3 v3.2.1 h1:RN9w6+7QoMeJVGyfmbcgs28Br8cvmnucEXnY0rYXWg0=
+github.com/Masterminds/semver/v3 v3.2.1/go.mod h1:qvl/7zhW3nngYb5+80sSMF+FG2BjYrf8m9wsX0PNOMQ=
+github.com/dlclark/regexp2 v1.11.4 h1:rPYF9/LECdNymJufQKmri9gV604RvvABwgOA8un7yAo=
+github.com/dlclark/regexp2 v1.11.4/go.mod h1:DHkYz0B9wPfa6wondMfaivmHpzrQ3v9q8cnmRbL6yW8=
+github.com/dop251/goja v0.0.0-20260106131823-651366fbe6e3 h1:bVp3yUzvSAJzu9GqID+Z96P+eu5TKnIMJSV4QaZMauM=
+github.com/dop251/goja v0.0.0-20260106131823-651366fbe6e3/go.mod h1:MxLav0peU43GgvwVgNbLAj1s/bSGboKkhuULvq/7hx4=
 github.com/go-flac/flacpicture v0.3.0 h1:LkmTxzFLIynwfhHiZsX0s8xcr3/u33MzvV89u+zOT8I=
 github.com/go-flac/flacpicture v0.3.0/go.mod h1:DPbrzVYQ3fJcvSgLFp9HXIrEQEdfdk/+m0nQCzwodZI=
 github.com/go-flac/flacvorbis v0.2.0 h1:KH0xjpkNTXFER4cszH4zeJxYcrHbUobz/RticWGOESs=
 github.com/go-flac/flacvorbis v0.2.0/go.mod h1:uIysHOtuU7OLGoCRG92bvnkg7QEqHx19qKRV6K1pBrI=
 github.com/go-flac/go-flac v1.0.0 h1:6qI9XOVLcO50xpzm3nXvO31BgDgHhnr/p/rER/K/doY=
 github.com/go-flac/go-flac v1.0.0/go.mod h1:WnZhcpmq4u1UdZMNn9LYSoASpWOCMOoxXxcWEHSzkW8=
+github.com/go-sourcemap/sourcemap v2.1.3+incompatible h1:W1iEw64niKVGogNgBN3ePyLFfuisuzeidWPMPWmECqU=
+github.com/go-sourcemap/sourcemap v2.1.3+incompatible/go.mod h1:F8jJfvm2KbVjc5NqelyYJmf/v5J0dwNLS2mL4sNA1Jg=
+github.com/google/pprof v0.0.0-20230207041349-798e818bf904 h1:4/hN5RUoecvl+RmJRE2YxKWtnnQls6rQjjW5oV7qg2U=
+github.com/google/pprof v0.0.0-20230207041349-798e818bf904/go.mod h1:uglQLonpP8qtYCYyzA+8c/9qtqgA3qsXGYqCPKARAFg=
 golang.org/x/mobile v0.0.0-20251209145715-2553ed8ce294 h1:Cr6kbEvA6nqvdHynE4CtVKlqpZB9dS1Jva/6IsHA19g=
 golang.org/x/mobile v0.0.0-20251209145715-2553ed8ce294/go.mod h1:RdZ+3sb4CVgpCFnzv+I4haEpwqFfsfzlLHs3L7ok+e0=
 golang.org/x/mod v0.31.0 h1:HaW9xtz0+kOcWKwli0ZXy79Ix+UW/vOfmWI5QVd2tgI=
 golang.org/x/mod v0.31.0/go.mod h1:43JraMp9cGx1Rx3AqioxrbrhNsLl2l/iNAvuBkrezpg=
 golang.org/x/sync v0.19.0 h1:vV+1eWNmZ5geRlYjzm2adRgW2/mcpevXNg50YZtPCE4=
 golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
+golang.org/x/text v0.3.8 h1:nAL+RVCQ9uMn3vJZbV+MRnydTJFPf8qqY42YiA6MrqY=
+golang.org/x/text v0.3.8/go.mod h1:E6s5w1FMmriuDzIBO73fBruAKo1PCIq6d2Q6DHfQ8WQ=
 golang.org/x/tools v0.40.0 h1:yLkxfA+Qnul4cs9QA3KnlFu0lVmd8JJfoq+E41uSutA=
 golang.org/x/tools v0.40.0/go.mod h1:Ik/tzLRlbscWpqqMRjyWYDisX8bG13FrdXp3o4Sr9lc=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=

go_backend/httputil.go

@@ -1,48 +1,90 @@
 package gobackend
 
 import (
+	"crypto/tls"
+	"errors"
 	"fmt"
 	"io"
 	"math/rand"
 	"net"
 	"net/http"
+	"net/url"
 	"strconv"
+	"strings"
+	"syscall"
 	"time"
 )
 
 // HTTP utility functions for consistent request handling across all downloaders
 
-// User-Agent pool for Android Chrome browsers
-var userAgentTemplates = []string{
-	"Mozilla/5.0 (Linux; Android %d; SM-G%d) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/%d.0.%d.%d Mobile Safari/537.36",
-	"Mozilla/5.0 (Linux; Android %d; Pixel %d) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/%d.0.%d.%d Mobile Safari/537.36",
-	"Mozilla/5.0 (Linux; Android %d; SM-A%d) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/%d.0.%d.%d Mobile Safari/537.36",
-	"Mozilla/5.0 (Linux; Android %d; Redmi Note %d) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/%d.0.%d.%d Mobile Safari/537.36",
-}
-
-// getRandomUserAgent generates a random browser-like User-Agent string (Android Chrome format)
+// getRandomUserAgent generates a random Windows Chrome User-Agent string
+// Uses same format as PC version (referensi/backend/spotify_metadata.go) for better API compatibility
 func getRandomUserAgent() string {
-	template := userAgentTemplates[rand.Intn(len(userAgentTemplates))]
+	// Windows 10/11 Chrome format - same as PC version for maximum compatibility
+	// Some APIs may block mobile User-Agents, so we use desktop format
+	winMajor := rand.Intn(2) + 10 // Windows 10 or 11
 
-	androidVersion := rand.Intn(5) + 10 // Android 10-14
-	deviceModel := rand.Intn(900) + 100 // Random model number
-	chromeVersion := rand.Intn(25) + 100 // Chrome 100-124
-	chromeBuild := rand.Intn(5000) + 5000
-	chromePatch := rand.Intn(200) + 100
+	chromeVersion := rand.Intn(25) + 100  // Chrome 100-124
+	chromeBuild := rand.Intn(1500) + 3000 // Build 3000-4500
+	chromePatch := rand.Intn(65) + 60     // Patch 60-125
 
-	return fmt.Sprintf(template, androidVersion, deviceModel, chromeVersion, chromeBuild, chromePatch)
+	return fmt.Sprintf(
+		"Mozilla/5.0 (Windows NT %d.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/%d.0.%d.%d Safari/537.36",
+		winMajor,
+		chromeVersion,
+		chromeBuild,
+		chromePatch,
+	)
 }
 
+// getRandomMacUserAgent generates a random Mac Chrome User-Agent string
+// Alternative format matching referensi/backend/spotify_metadata.go exactly
+// Kept for potential future use
+// func getRandomMacUserAgent() string {
+// 	macMajor := rand.Intn(4) + 11 // macOS 11-14
+// 	macMinor := rand.Intn(5) + 4  // Minor 4-8
+// 	webkitMajor := rand.Intn(7) + 530
+// 	webkitMinor := rand.Intn(7) + 30
+// 	chromeMajor := rand.Intn(25) + 80
+// 	chromeBuild := rand.Intn(1500) + 3000
+// 	chromePatch := rand.Intn(65) + 60
+// 	safariMajor := rand.Intn(7) + 530
+// 	safariMinor := rand.Intn(6) + 30
+//
+// 	return fmt.Sprintf(
+// 		"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_%d_%d) AppleWebKit/%d.%d (KHTML, like Gecko) Chrome/%d.0.%d.%d Safari/%d.%d",
+// 		macMajor,
+// 		macMinor,
+// 		webkitMajor,
+// 		webkitMinor,
+// 		chromeMajor,
+// 		chromeBuild,
+// 		chromePatch,
+// 		safariMajor,
+// 		safariMinor,
+// 	)
+// }
+
+// getRandomDesktopUserAgent randomly picks between Windows and Mac User-Agent
+// Kept for potential future use
+// func getRandomDesktopUserAgent() string {
+// 	if rand.Intn(2) == 0 {
+// 		return getRandomUserAgent() // Windows
+// 	}
+// 	return getRandomMacUserAgent() // Mac
+// }
+
 // Default timeout values
 const (
-	DefaultTimeout     = 60 * time.Second  // Default HTTP timeout
-	DownloadTimeout    = 120 * time.Second // Timeout for file downloads
-	SongLinkTimeout    = 30 * time.Second  // Timeout for SongLink API
-	DefaultMaxRetries  = 3                 // Default retry count
-	DefaultRetryDelay  = 1 * time.Second   // Initial retry delay
+	DefaultTimeout    = 60 * time.Second  // Default HTTP timeout
+	DownloadTimeout   = 120 * time.Second // Timeout for file downloads
+	SongLinkTimeout   = 30 * time.Second  // Timeout for SongLink API
+	DefaultMaxRetries = 3                 // Default retry count
+	DefaultRetryDelay = 1 * time.Second   // Initial retry delay
 )
 
 // Shared transport with connection pooling to prevent TCP exhaustion
+// Optimized for large file downloads (FLAC ~30-50MB)
 var sharedTransport = &http.Transport{
 	DialContext: (&net.Dialer{
 		Timeout:   30 * time.Second,
@@ -56,6 +98,9 @@ var sharedTransport = &http.Transport{
 	ExpectContinueTimeout: 1 * time.Second,
 	DisableKeepAlives:     false, // Enable keep-alives for connection reuse
 	ForceAttemptHTTP2:     true,
+	WriteBufferSize:       64 * 1024, // 64KB write buffer
+	ReadBufferSize:        64 * 1024, // 64KB read buffer
+	DisableCompression:    true,      // FLAC is already compressed
 }
 
 // Shared HTTP client for general requests (reuses connections)
@@ -96,9 +141,15 @@ func CloseIdleConnections() {
 }
 
 // DoRequestWithUserAgent executes an HTTP request with a random User-Agent header
+// Also checks for ISP blocking on errors
 func DoRequestWithUserAgent(client *http.Client, req *http.Request) (*http.Response, error) {
 	req.Header.Set("User-Agent", getRandomUserAgent())
-	return client.Do(req)
+	resp, err := client.Do(req)
+	if err != nil {
+		// Check for ISP blocking
+		CheckAndLogISPBlocking(err, req.URL.String(), "HTTP")
+	}
+	return resp, err
 }
 
 // RetryConfig holds configuration for retry logic
@@ -121,9 +172,11 @@ func DefaultRetryConfig() RetryConfig {
 
 // DoRequestWithRetry executes an HTTP request with retry logic and exponential backoff
 // Handles 429 (Too Many Requests) responses with Retry-After header
+// Also detects and logs ISP blocking
 func DoRequestWithRetry(client *http.Client, req *http.Request, config RetryConfig) (*http.Response, error) {
 	var lastErr error
 	delay := config.InitialDelay
+	requestURL := req.URL.String()
 
 	for attempt := 0; attempt <= config.MaxRetries; attempt++ {
 		// Clone request for retry (body needs to be re-readable)
@@ -133,7 +186,16 @@ func DoRequestWithRetry(client *http.Client, req *http.Request, config RetryConf
 		resp, err := client.Do(reqCopy)
 		if err != nil {
 			lastErr = err
+
+			// Check for ISP blocking on network errors
+			if CheckAndLogISPBlocking(err, requestURL, "HTTP") {
+				// Don't retry if ISP blocking is detected - it won't help
+				return nil, WrapErrorWithISPCheck(err, requestURL, "HTTP")
+			}
+
 			if attempt < config.MaxRetries {
+				GoLog("[HTTP] Request failed (attempt %d/%d): %v, retrying in %v...\n",
+					attempt+1, config.MaxRetries+1, err, delay)
 				time.Sleep(delay)
 				delay = calculateNextDelay(delay, config)
 			}
@@ -154,17 +216,43 @@ func DoRequestWithRetry(client *http.Client, req *http.Request, config RetryConf
 			}
 			lastErr = fmt.Errorf("rate limited (429)")
 			if attempt < config.MaxRetries {
+				GoLog("[HTTP] Rate limited, waiting %v before retry...\n", delay)
 				time.Sleep(delay)
 				delay = calculateNextDelay(delay, config)
 			}
 			continue
 		}
 
+		// Check for ISP blocking via HTTP status codes
+		// Some ISPs return 403 or 451 when blocking content
+		if resp.StatusCode == 403 || resp.StatusCode == 451 {
+			body, _ := io.ReadAll(resp.Body)
+			resp.Body.Close()
+			bodyStr := strings.ToLower(string(body))
+
+			// Check if response looks like ISP blocking page
+			ispBlockingIndicators := []string{
+				"blocked", "forbidden", "access denied", "not available in your",
+				"restricted", "censored", "unavailable for legal", "blocked by",
+			}
+
+			for _, indicator := range ispBlockingIndicators {
+				if strings.Contains(bodyStr, indicator) {
+					LogError("HTTP", "ISP BLOCKING DETECTED via HTTP %d response", resp.StatusCode)
+					LogError("HTTP", "Domain: %s", req.URL.Host)
+					LogError("HTTP", "Response contains: %s", indicator)
+					LogError("HTTP", "Suggestion: Try using a VPN or changing your DNS to 1.1.1.1 or 8.8.8.8")
+					return nil, fmt.Errorf("ISP blocking detected for %s (HTTP %d) - try using VPN or change DNS", req.URL.Host, resp.StatusCode)
+				}
+			}
+		}
+
 		// Server errors (5xx) - retry
 		if resp.StatusCode >= 500 {
 			resp.Body.Close()
 			lastErr = fmt.Errorf("server error: HTTP %d", resp.StatusCode)
 			if attempt < config.MaxRetries {
+				GoLog("[HTTP] Server error %d, retrying in %v...\n", resp.StatusCode, delay)
 				time.Sleep(delay)
 				delay = calculateNextDelay(delay, config)
 			}
@@ -181,10 +269,7 @@ func DoRequestWithRetry(client *http.Client, req *http.Request, config RetryConf
 // calculateNextDelay calculates the next delay with exponential backoff
 func calculateNextDelay(currentDelay time.Duration, config RetryConfig) time.Duration {
 	nextDelay := time.Duration(float64(currentDelay) * config.BackoffFactor)
-	if nextDelay > config.MaxDelay {
-		nextDelay = config.MaxDelay
-	}
-	return nextDelay
+	return min(nextDelay, config.MaxDelay)
 }
 
 // getRetryAfterDuration parses Retry-After header and returns duration
@@ -258,3 +343,172 @@ func BuildErrorMessage(apiURL string, statusCode int, responsePreview string) st
 	}
 	return msg
 }
+
+// ISPBlockingError represents an error caused by ISP blocking
+type ISPBlockingError struct {
+	Domain      string
+	Reason      string
+	OriginalErr error
+}
+
+func (e *ISPBlockingError) Error() string {
+	return fmt.Sprintf("ISP blocking detected for %s: %s", e.Domain, e.Reason)
+}
+
+// IsISPBlocking checks if an error is likely caused by ISP blocking
+// Returns the ISPBlockingError if detected, nil otherwise
+func IsISPBlocking(err error, requestURL string) *ISPBlockingError {
+	if err == nil {
+		return nil
+	}
+
+	// Extract domain from URL
+	domain := extractDomain(requestURL)
+	errStr := strings.ToLower(err.Error())
+
+	// Check for DNS resolution failure (common ISP blocking method)
+	var dnsErr *net.DNSError
+	if errors.As(err, &dnsErr) {
+		if dnsErr.IsNotFound || dnsErr.IsTemporary {
+			return &ISPBlockingError{
+				Domain:      domain,
+				Reason:      "DNS resolution failed - domain may be blocked by ISP",
+				OriginalErr: err,
+			}
+		}
+	}
+
+	// Check for connection refused (ISP firewall blocking)
+	var opErr *net.OpError
+	if errors.As(err, &opErr) {
+		if opErr.Op == "dial" {
+			// Check for specific syscall errors
+			var syscallErr syscall.Errno
+			if errors.As(opErr.Err, &syscallErr) {
+				switch syscallErr {
+				case syscall.ECONNREFUSED:
+					return &ISPBlockingError{
+						Domain:      domain,
+						Reason:      "Connection refused - port may be blocked by ISP/firewall",
+						OriginalErr: err,
+					}
+				case syscall.ECONNRESET:
+					return &ISPBlockingError{
+						Domain:      domain,
+						Reason:      "Connection reset - ISP may be intercepting traffic",
+						OriginalErr: err,
+					}
+				case syscall.ETIMEDOUT:
+					return &ISPBlockingError{
+						Domain:      domain,
+						Reason:      "Connection timed out - ISP may be blocking access",
+						OriginalErr: err,
+					}
+				case syscall.ENETUNREACH:
+					return &ISPBlockingError{
+						Domain:      domain,
+						Reason:      "Network unreachable - ISP may be blocking route",
+						OriginalErr: err,
+					}
+				case syscall.EHOSTUNREACH:
+					return &ISPBlockingError{
+						Domain:      domain,
+						Reason:      "Host unreachable - ISP may be blocking destination",
+						OriginalErr: err,
+					}
+				}
+			}
+		}
+	}
+
+	// Check for TLS handshake failure (ISP MITM or blocking HTTPS)
+	var tlsErr *tls.RecordHeaderError
+	if errors.As(err, &tlsErr) {
+		return &ISPBlockingError{
+			Domain:      domain,
+			Reason:      "TLS handshake failed - ISP may be intercepting HTTPS traffic",
+			OriginalErr: err,
+		}
+	}
+
+	// Check error message patterns for common ISP blocking indicators
+	blockingPatterns := []struct {
+		pattern string
+		reason  string
+	}{
+		{"connection reset by peer", "Connection reset - ISP may be intercepting traffic"},
+		{"connection refused", "Connection refused - port may be blocked"},
+		{"no such host", "DNS lookup failed - domain may be blocked by ISP"},
+		{"i/o timeout", "Connection timed out - ISP may be blocking access"},
+		{"network is unreachable", "Network unreachable - ISP may be blocking route"},
+		{"tls: ", "TLS error - ISP may be intercepting HTTPS traffic"},
+		{"certificate", "Certificate error - ISP may be using MITM proxy"},
+		{"eof", "Connection closed unexpectedly - ISP may be blocking"},
+		{"context deadline exceeded", "Request timed out - ISP may be throttling"},
+	}
+
+	for _, bp := range blockingPatterns {
+		if strings.Contains(errStr, bp.pattern) {
+			return &ISPBlockingError{
+				Domain:      domain,
+				Reason:      bp.reason,
+				OriginalErr: err,
+			}
+		}
+	}
+
+	return nil
+}
+
+// CheckAndLogISPBlocking checks for ISP blocking and logs if detected
+// Returns true if ISP blocking was detected
+func CheckAndLogISPBlocking(err error, requestURL string, tag string) bool {
+	ispErr := IsISPBlocking(err, requestURL)
+	if ispErr != nil {
+		LogError(tag, "ISP BLOCKING DETECTED: %s", ispErr.Error())
+		LogError(tag, "Domain: %s", ispErr.Domain)
+		LogError(tag, "Reason: %s", ispErr.Reason)
+		LogError(tag, "Original error: %v", ispErr.OriginalErr)
+		LogError(tag, "Suggestion: Try using a VPN or changing your DNS to 1.1.1.1 or 8.8.8.8")
+		return true
+	}
+	return false
+}
+
+// extractDomain extracts the domain from a URL string
+func extractDomain(rawURL string) string {
+	if rawURL == "" {
+		return "unknown"
+	}
+
+	parsed, err := url.Parse(rawURL)
+	if err != nil {
+		// Try to extract domain manually
+		rawURL = strings.TrimPrefix(rawURL, "https://")
+		rawURL = strings.TrimPrefix(rawURL, "http://")
+		if idx := strings.Index(rawURL, "/"); idx > 0 {
+			return rawURL[:idx]
+		}
+		return rawURL
+	}
+
+	if parsed.Host != "" {
+		return parsed.Host
+	}
+	return "unknown"
+}
+
+// WrapErrorWithISPCheck wraps an error with ISP blocking detection
+// If ISP blocking is detected, returns a more descriptive error
+func WrapErrorWithISPCheck(err error, requestURL string, tag string) error {
+	if err == nil {
+		return nil
+	}
+
+	if CheckAndLogISPBlocking(err, requestURL, tag) {
+		domain := extractDomain(requestURL)
+		return fmt.Errorf("ISP blocking detected for %s - try using VPN or change DNS to 1.1.1.1/8.8.8.8: %w", domain, err)
+	}
+
+	return err
+}

go_backend/logbuffer.go

@@ -0,0 +1,203 @@
+package gobackend
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+	"sync"
+	"time"
+)
+
+// LogEntry represents a single log entry
+type LogEntry struct {
+	Timestamp string `json:"timestamp"`
+	Level     string `json:"level"`
+	Tag       string `json:"tag"`
+	Message   string `json:"message"`
+}
+
+// LogBuffer stores logs in a circular buffer for retrieval by Flutter
+type LogBuffer struct {
+	entries        []LogEntry
+	maxSize        int
+	mu             sync.RWMutex
+	loggingEnabled bool // Whether logging is enabled (controlled by Flutter)
+}
+
+var (
+	globalLogBuffer *LogBuffer
+	logBufferOnce   sync.Once
+)
+
+// GetLogBuffer returns the singleton log buffer instance
+func GetLogBuffer() *LogBuffer {
+	logBufferOnce.Do(func() {
+		globalLogBuffer = &LogBuffer{
+			entries:        make([]LogEntry, 0, 500),
+			maxSize:        500,
+			loggingEnabled: false, // Default: disabled for performance (user can enable in settings)
+		}
+	})
+	return globalLogBuffer
+}
+
+// SetLoggingEnabled enables or disables logging
+func (lb *LogBuffer) SetLoggingEnabled(enabled bool) {
+	lb.mu.Lock()
+	defer lb.mu.Unlock()
+	lb.loggingEnabled = enabled
+}
+
+// IsLoggingEnabled returns whether logging is enabled
+func (lb *LogBuffer) IsLoggingEnabled() bool {
+	lb.mu.RLock()
+	defer lb.mu.RUnlock()
+	return lb.loggingEnabled
+}
+
+// Add adds a log entry to the buffer
+func (lb *LogBuffer) Add(level, tag, message string) {
+	lb.mu.Lock()
+	defer lb.mu.Unlock()
+
+	// Skip if logging is disabled (except for errors which are always logged)
+	if !lb.loggingEnabled && level != "ERROR" && level != "FATAL" {
+		return
+	}
+
+	entry := LogEntry{
+		Timestamp: time.Now().Format("15:04:05.000"),
+		Level:     level,
+		Tag:       tag,
+		Message:   message,
+	}
+
+	if len(lb.entries) >= lb.maxSize {
+		// Remove oldest entry
+		lb.entries = lb.entries[1:]
+	}
+	lb.entries = append(lb.entries, entry)
+
+	// Also print to logcat for debugging
+	fmt.Printf("[%s] %s\n", tag, message)
+}
+
+// GetAll returns all log entries as JSON
+func (lb *LogBuffer) GetAll() string {
+	lb.mu.RLock()
+	defer lb.mu.RUnlock()
+
+	jsonBytes, _ := json.Marshal(lb.entries)
+	return string(jsonBytes)
+}
+
+// getSince returns log entries since the given index (internal use)
+func (lb *LogBuffer) getSince(index int) ([]LogEntry, int) {
+	lb.mu.RLock()
+	defer lb.mu.RUnlock()
+
+	if index < 0 {
+		index = 0
+	}
+	if index >= len(lb.entries) {
+		return []LogEntry{}, len(lb.entries)
+	}
+
+	entries := lb.entries[index:]
+	return entries, len(lb.entries)
+}
+
+// Clear clears all log entries
+func (lb *LogBuffer) Clear() {
+	lb.mu.Lock()
+	defer lb.mu.Unlock()
+	lb.entries = lb.entries[:0]
+}
+
+// Count returns the number of log entries
+func (lb *LogBuffer) Count() int {
+	lb.mu.RLock()
+	defer lb.mu.RUnlock()
+	return len(lb.entries)
+}
+
+// Helper functions for logging with different levels
+func LogDebug(tag, format string, args ...interface{}) {
+	GetLogBuffer().Add("DEBUG", tag, fmt.Sprintf(format, args...))
+}
+
+func LogInfo(tag, format string, args ...interface{}) {
+	GetLogBuffer().Add("INFO", tag, fmt.Sprintf(format, args...))
+}
+
+func LogWarn(tag, format string, args ...interface{}) {
+	GetLogBuffer().Add("WARN", tag, fmt.Sprintf(format, args...))
+}
+
+func LogError(tag, format string, args ...interface{}) {
+	GetLogBuffer().Add("ERROR", tag, fmt.Sprintf(format, args...))
+}
+
+// GoLog is a drop-in replacement for fmt.Printf that also logs to buffer
+// It parses the tag from the format string if it starts with [Tag]
+func GoLog(format string, args ...interface{}) {
+	message := fmt.Sprintf(format, args...)
+	message = strings.TrimSuffix(message, "\n")
+
+	// Extract tag from message if present (e.g., "[Tidal] message")
+	tag := "Go"
+	level := "INFO"
+
+	if strings.HasPrefix(message, "[") {
+		endBracket := strings.Index(message, "]")
+		if endBracket > 1 {
+			tag = message[1:endBracket]
+			message = strings.TrimSpace(message[endBracket+1:])
+		}
+	}
+
+	// Determine level from message content
+	msgLower := strings.ToLower(message)
+	if strings.Contains(msgLower, "error") || strings.Contains(msgLower, "failed") || strings.HasPrefix(message, "✗") {
+		level = "ERROR"
+	} else if strings.Contains(msgLower, "warning") || strings.Contains(msgLower, "warn") {
+		level = "WARN"
+	} else if strings.HasPrefix(message, "✓") || strings.Contains(msgLower, "success") || strings.Contains(msgLower, "match found") {
+		level = "INFO"
+	} else if strings.Contains(msgLower, "searching") || strings.Contains(msgLower, "trying") || strings.Contains(msgLower, "found") {
+		level = "DEBUG"
+	}
+
+	GetLogBuffer().Add(level, tag, message)
+}
+
+// Exported functions for Flutter
+
+// GetLogs returns all logs as JSON array
+func GetLogs() string {
+	return GetLogBuffer().GetAll()
+}
+
+// GetLogsSince returns logs since the given index
+// Returns JSON: {"logs": [...], "next_index": N}
+func GetLogsSince(index int) string {
+	entries, nextIndex := GetLogBuffer().getSince(index)
+	logsJson, _ := json.Marshal(entries)
+	result := fmt.Sprintf(`{"logs":%s,"next_index":%d}`, string(logsJson), nextIndex)
+	return result
+}
+
+// ClearLogs clears all logs
+func ClearLogs() {
+	GetLogBuffer().Clear()
+}
+
+// GetLogCount returns the number of log entries
+func GetLogCount() int {
+	return GetLogBuffer().Count()
+}
+
+// SetLoggingEnabled enables or disables logging from Flutter
+func SetLoggingEnabled(enabled bool) {
+	GetLogBuffer().SetLoggingEnabled(enabled)
+}

go_backend/lyrics.go

@@ -248,15 +248,54 @@ func msToLRCTimestamp(ms int64) string {
 	return fmt.Sprintf("[%02d:%02d.%02d]", minutes, seconds, centiseconds)
 }
 
-func convertToLRC(lyrics *LyricsResponse) string {
+// convertToLRC converts lyrics to LRC format string (without metadata headers)
+// Use convertToLRCWithMetadata for full LRC with headers
+// Kept for potential future use
+// func convertToLRC(lyrics *LyricsResponse) string {
+// 	if lyrics == nil || len(lyrics.Lines) == 0 {
+// 		return ""
+// 	}
+//
+// 	var builder strings.Builder
+//
+// 	if lyrics.SyncType == "LINE_SYNCED" {
+// 		for _, line := range lyrics.Lines {
+// 			timestamp := msToLRCTimestamp(line.StartTimeMs)
+// 			builder.WriteString(timestamp)
+// 			builder.WriteString(line.Words)
+// 			builder.WriteString("\n")
+// 		}
+// 	} else {
+// 		for _, line := range lyrics.Lines {
+// 			builder.WriteString(line.Words)
+// 			builder.WriteString("\n")
+// 		}
+// 	}
+//
+// 	return builder.String()
+// }
+
+// convertToLRCWithMetadata converts lyrics to LRC format with metadata headers
+// Includes [ti:], [ar:], [by:] headers
+func convertToLRCWithMetadata(lyrics *LyricsResponse, trackName, artistName string) string {
 	if lyrics == nil || len(lyrics.Lines) == 0 {
 		return ""
 	}
 
 	var builder strings.Builder
 
+	// Add metadata headers
+	builder.WriteString(fmt.Sprintf("[ti:%s]\n", trackName))
+	builder.WriteString(fmt.Sprintf("[ar:%s]\n", artistName))
+	builder.WriteString("[by:SpotiFLAC-Mobile]\n")
+	builder.WriteString("\n")
+
+	// Add lyrics lines
 	if lyrics.SyncType == "LINE_SYNCED" {
 		for _, line := range lyrics.Lines {
+			if line.Words == "" {
+				continue
+			}
 			timestamp := msToLRCTimestamp(line.StartTimeMs)
 			builder.WriteString(timestamp)
 			builder.WriteString(line.Words)
@@ -264,6 +303,9 @@ func convertToLRC(lyrics *LyricsResponse) string {
 		}
 	} else {
 		for _, line := range lyrics.Lines {
+			if line.Words == "" {
+				continue
+			}
 			builder.WriteString(line.Words)
 			builder.WriteString("\n")
 		}

go_backend/metadata.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"strconv"
+	"strings"
 
 	"github.com/go-flac/flacpicture"
 	"github.com/go-flac/flacvorbis"
@@ -57,7 +58,7 @@ func EmbedMetadata(filePath string, metadata Metadata, coverPath string) error {
 	setComment(cmt, "ALBUM", metadata.Album)
 	setComment(cmt, "ALBUMARTIST", metadata.AlbumArtist)
 	setComment(cmt, "DATE", metadata.Date)
-	
+
 	if metadata.TrackNumber > 0 {
 		if metadata.TotalTracks > 0 {
 			setComment(cmt, "TRACKNUMBER", fmt.Sprintf("%d/%d", metadata.TrackNumber, metadata.TotalTracks))
@@ -65,15 +66,15 @@ func EmbedMetadata(filePath string, metadata Metadata, coverPath string) error {
 			setComment(cmt, "TRACKNUMBER", strconv.Itoa(metadata.TrackNumber))
 		}
 	}
-	
+
 	if metadata.DiscNumber > 0 {
 		setComment(cmt, "DISCNUMBER", strconv.Itoa(metadata.DiscNumber))
 	}
-	
+
 	if metadata.ISRC != "" {
 		setComment(cmt, "ISRC", metadata.ISRC)
 	}
-	
+
 	if metadata.Description != "" {
 		setComment(cmt, "DESCRIPTION", metadata.Description)
 	}
@@ -104,7 +105,7 @@ func EmbedMetadata(filePath string, metadata Metadata, coverPath string) error {
 						f.Meta = append(f.Meta[:i], f.Meta[i+1:]...)
 					}
 				}
-				
+
 				picture, err := flacpicture.NewFromImageData(
 					flacpicture.PictureTypeFrontCover,
 					"Front Cover",
@@ -161,7 +162,7 @@ func EmbedMetadataWithCoverData(filePath string, metadata Metadata, coverData []
 	setComment(cmt, "ALBUM", metadata.Album)
 	setComment(cmt, "ALBUMARTIST", metadata.AlbumArtist)
 	setComment(cmt, "DATE", metadata.Date)
-	
+
 	if metadata.TrackNumber > 0 {
 		if metadata.TotalTracks > 0 {
 			setComment(cmt, "TRACKNUMBER", fmt.Sprintf("%d/%d", metadata.TrackNumber, metadata.TotalTracks))
@@ -169,15 +170,15 @@ func EmbedMetadataWithCoverData(filePath string, metadata Metadata, coverData []
 			setComment(cmt, "TRACKNUMBER", strconv.Itoa(metadata.TrackNumber))
 		}
 	}
-	
+
 	if metadata.DiscNumber > 0 {
 		setComment(cmt, "DISCNUMBER", strconv.Itoa(metadata.DiscNumber))
 	}
-	
+
 	if metadata.ISRC != "" {
 		setComment(cmt, "ISRC", metadata.ISRC)
 	}
-	
+
 	if metadata.Description != "" {
 		setComment(cmt, "DESCRIPTION", metadata.Description)
 	}
@@ -203,7 +204,7 @@ func EmbedMetadataWithCoverData(filePath string, metadata Metadata, coverData []
 				f.Meta = append(f.Meta[:i], f.Meta[i+1:]...)
 			}
 		}
-		
+
 		picture, err := flacpicture.NewFromImageData(
 			flacpicture.PictureTypeFrontCover,
 			"Front Cover",
@@ -256,11 +257,30 @@ func ReadMetadata(filePath string) (*Metadata, error) {
 			if trackNum != "" {
 				fmt.Sscanf(trackNum, "%d", &metadata.TrackNumber)
 			}
+			// Also try lowercase variant (some encoders use lowercase)
+			if metadata.TrackNumber == 0 {
+				trackNum = getComment(cmt, "TRACK")
+				if trackNum != "" {
+					fmt.Sscanf(trackNum, "%d", &metadata.TrackNumber)
+				}
+			}
 
 			discNum := getComment(cmt, "DISCNUMBER")
 			if discNum != "" {
 				fmt.Sscanf(discNum, "%d", &metadata.DiscNumber)
 			}
+			// Also try DISC variant
+			if metadata.DiscNumber == 0 {
+				discNum = getComment(cmt, "DISC")
+				if discNum != "" {
+					fmt.Sscanf(discNum, "%d", &metadata.DiscNumber)
+				}
+			}
+
+			// Try DATE variants
+			if metadata.Date == "" {
+				metadata.Date = getComment(cmt, "YEAR")
+			}
 
 			break
 		}
@@ -273,10 +293,16 @@ func setComment(cmt *flacvorbis.MetaDataBlockVorbisComment, key, value string) {
 	if value == "" {
 		return
 	}
-	// Remove existing
+	// Remove existing (case-insensitive comparison for Vorbis comments)
+	keyUpper := strings.ToUpper(key)
 	for i := len(cmt.Comments) - 1; i >= 0; i-- {
-		if len(cmt.Comments[i]) > len(key)+1 && cmt.Comments[i][:len(key)+1] == key+"=" {
-			cmt.Comments = append(cmt.Comments[:i], cmt.Comments[i+1:]...)
+		comment := cmt.Comments[i]
+		eqIdx := strings.Index(comment, "=")
+		if eqIdx > 0 {
+			existingKey := strings.ToUpper(comment[:eqIdx])
+			if existingKey == keyUpper {
+				cmt.Comments = append(cmt.Comments[:i], cmt.Comments[i+1:]...)
+			}
 		}
 	}
 	// Add new
@@ -284,9 +310,14 @@ func setComment(cmt *flacvorbis.MetaDataBlockVorbisComment, key, value string) {
 }
 
 func getComment(cmt *flacvorbis.MetaDataBlockVorbisComment, key string) string {
+	keyUpper := strings.ToUpper(key) + "="
 	for _, comment := range cmt.Comments {
-		if len(comment) > len(key)+1 && comment[:len(key)+1] == key+"=" {
-			return comment[len(key)+1:]
+		if len(comment) > len(key) {
+			// Case-insensitive comparison for Vorbis comments
+			commentUpper := strings.ToUpper(comment[:len(key)+1])
+			if commentUpper == keyUpper {
+				return comment[len(key)+1:]
+			}
 		}
 	}
 	return ""
@@ -335,3 +366,457 @@ func EmbedLyrics(filePath string, lyrics string) error {
 
 	return f.Save(filePath)
 }
+
+// ExtractLyrics extracts embedded lyrics from a FLAC file
+func ExtractLyrics(filePath string) (string, error) {
+	f, err := flac.ParseFile(filePath)
+	if err != nil {
+		return "", fmt.Errorf("failed to parse FLAC file: %w", err)
+	}
+
+	for _, meta := range f.Meta {
+		if meta.Type == flac.VorbisComment {
+			cmt, err := flacvorbis.ParseFromMetaDataBlock(*meta)
+			if err != nil {
+				continue
+			}
+
+			// Try LYRICS tag first
+			lyrics, err := cmt.Get("LYRICS")
+			if err == nil && len(lyrics) > 0 && lyrics[0] != "" {
+				return lyrics[0], nil
+			}
+
+			// Fallback to UNSYNCEDLYRICS
+			lyrics, err = cmt.Get("UNSYNCEDLYRICS")
+			if err == nil && len(lyrics) > 0 && lyrics[0] != "" {
+				return lyrics[0], nil
+			}
+		}
+	}
+
+	return "", fmt.Errorf("no lyrics found in file")
+}
+
+// AudioQuality represents audio quality info from a FLAC file
+type AudioQuality struct {
+	BitDepth     int   `json:"bit_depth"`
+	SampleRate   int   `json:"sample_rate"`
+	TotalSamples int64 `json:"total_samples"`
+}
+
+// GetAudioQuality reads bit depth and sample rate from a FLAC file's StreamInfo block
+// FLAC StreamInfo is always the first metadata block after the 4-byte "fLaC" marker
+// For M4A files, it delegates to GetM4AQuality
+func GetAudioQuality(filePath string) (AudioQuality, error) {
+	file, err := os.Open(filePath)
+	if err != nil {
+		return AudioQuality{}, fmt.Errorf("failed to open file: %w", err)
+	}
+	defer file.Close()
+
+	// Read first 4 bytes to detect file type
+	marker := make([]byte, 4)
+	if _, err := file.Read(marker); err != nil {
+		return AudioQuality{}, fmt.Errorf("failed to read marker: %w", err)
+	}
+
+	// Check if it's a FLAC file
+	if string(marker) == "fLaC" {
+		// Continue reading FLAC metadata
+		// Read metadata block header (4 bytes)
+		header := make([]byte, 4)
+		if _, err := file.Read(header); err != nil {
+			return AudioQuality{}, fmt.Errorf("failed to read header: %w", err)
+		}
+
+		blockType := header[0] & 0x7F
+		if blockType != 0 {
+			return AudioQuality{}, fmt.Errorf("first block is not STREAMINFO")
+		}
+
+		// Read STREAMINFO block (34 bytes minimum)
+		streamInfo := make([]byte, 34)
+		if _, err := file.Read(streamInfo); err != nil {
+			return AudioQuality{}, fmt.Errorf("failed to read STREAMINFO: %w", err)
+		}
+
+		// Parse sample rate (20 bits starting at byte 10)
+		sampleRate := (int(streamInfo[10]) << 12) | (int(streamInfo[11]) << 4) | (int(streamInfo[12]) >> 4)
+
+		// Parse bits per sample (5 bits)
+		bitsPerSample := ((int(streamInfo[12]) & 0x01) << 4) | (int(streamInfo[13]) >> 4) + 1
+
+		// Parse total samples (36 bits: 4 bits from byte 13, all of bytes 14-17)
+		totalSamples := int64(streamInfo[13]&0x0F)<<32 |
+			int64(streamInfo[14])<<24 |
+			int64(streamInfo[15])<<16 |
+			int64(streamInfo[16])<<8 |
+			int64(streamInfo[17])
+
+		return AudioQuality{
+			BitDepth:     bitsPerSample,
+			SampleRate:   sampleRate,
+			TotalSamples: totalSamples,
+		}, nil
+	}
+
+	// Check if it's an M4A/MP4 file (starts with size + "ftyp")
+	// First 4 bytes are size, next 4 should be "ftyp"
+	file.Seek(0, 0) // Reset to beginning
+	header8 := make([]byte, 8)
+	if _, err := file.Read(header8); err != nil {
+		return AudioQuality{}, fmt.Errorf("failed to read header: %w", err)
+	}
+
+	if string(header8[4:8]) == "ftyp" {
+		// It's an M4A/MP4 file, use M4A quality reader
+		file.Close() // Close before calling GetM4AQuality which opens the file again
+		return GetM4AQuality(filePath)
+	}
+
+	return AudioQuality{}, fmt.Errorf("unsupported file format (not FLAC or M4A)")
+}
+
+// ========================================
+// M4A (MP4/AAC) Metadata Embedding
+// ========================================
+
+// EmbedM4AMetadata embeds metadata into an M4A file using iTunes-style atoms
+// This is a simplified implementation that writes metadata to the file
+func EmbedM4AMetadata(filePath string, metadata Metadata, coverData []byte) error {
+	// Read the entire file
+	data, err := os.ReadFile(filePath)
+	if err != nil {
+		return fmt.Errorf("failed to read M4A file: %w", err)
+	}
+
+	// Find moov atom position
+	moovPos := findAtom(data, "moov", 0)
+	if moovPos < 0 {
+		return fmt.Errorf("moov atom not found in M4A file")
+	}
+
+	// Find udta atom inside moov, or create one
+	moovSize := int(data[moovPos]<<24 | data[moovPos+1]<<16 | data[moovPos+2]<<8 | data[moovPos+3])
+	udtaPos := findAtom(data, "udta", moovPos+8)
+
+	// Build new metadata atoms
+	metaAtom := buildMetaAtom(metadata, coverData)
+
+	var newData []byte
+	if udtaPos >= 0 && udtaPos < moovPos+moovSize {
+		// udta exists, find meta inside it or replace
+		udtaSize := int(data[udtaPos]<<24 | data[udtaPos+1]<<16 | data[udtaPos+2]<<8 | data[udtaPos+3])
+		metaPos := findAtom(data, "meta", udtaPos+8)
+
+		if metaPos >= 0 && metaPos < udtaPos+udtaSize {
+			// Replace existing meta atom
+			metaSize := int(data[metaPos]<<24 | data[metaPos+1]<<16 | data[metaPos+2]<<8 | data[metaPos+3])
+			newData = append(newData, data[:metaPos]...)
+			newData = append(newData, metaAtom...)
+			newData = append(newData, data[metaPos+metaSize:]...)
+		} else {
+			// Add meta atom to udta
+			newUdtaContent := append(data[udtaPos+8:udtaPos+udtaSize], metaAtom...)
+			newUdtaSize := 8 + len(newUdtaContent)
+			newUdta := make([]byte, 4)
+			newUdta[0] = byte(newUdtaSize >> 24)
+			newUdta[1] = byte(newUdtaSize >> 16)
+			newUdta[2] = byte(newUdtaSize >> 8)
+			newUdta[3] = byte(newUdtaSize)
+			newUdta = append(newUdta, []byte("udta")...)
+			newUdta = append(newUdta, newUdtaContent...)
+
+			newData = append(newData, data[:udtaPos]...)
+			newData = append(newData, newUdta...)
+			newData = append(newData, data[udtaPos+udtaSize:]...)
+		}
+	} else {
+		// Create new udta with meta
+		udtaContent := metaAtom
+		udtaSize := 8 + len(udtaContent)
+		newUdta := make([]byte, 4)
+		newUdta[0] = byte(udtaSize >> 24)
+		newUdta[1] = byte(udtaSize >> 16)
+		newUdta[2] = byte(udtaSize >> 8)
+		newUdta[3] = byte(udtaSize)
+		newUdta = append(newUdta, []byte("udta")...)
+		newUdta = append(newUdta, udtaContent...)
+
+		// Insert udta at end of moov
+		insertPos := moovPos + moovSize
+		newData = append(newData, data[:insertPos]...)
+		newData = append(newData, newUdta...)
+		newData = append(newData, data[insertPos:]...)
+	}
+
+	// Update moov size
+	newMoovSize := moovSize + len(newData) - len(data)
+	newData[moovPos] = byte(newMoovSize >> 24)
+	newData[moovPos+1] = byte(newMoovSize >> 16)
+	newData[moovPos+2] = byte(newMoovSize >> 8)
+	newData[moovPos+3] = byte(newMoovSize)
+
+	// Write back to file
+	if err := os.WriteFile(filePath, newData, 0644); err != nil {
+		return fmt.Errorf("failed to write M4A file: %w", err)
+	}
+
+	fmt.Printf("[M4A] Metadata embedded successfully\n")
+	return nil
+}
+
+// findAtom finds an atom by name starting from offset
+func findAtom(data []byte, name string, offset int) int {
+	for i := offset; i < len(data)-8; {
+		size := int(data[i]<<24 | data[i+1]<<16 | data[i+2]<<8 | data[i+3])
+		if size < 8 {
+			break
+		}
+		atomName := string(data[i+4 : i+8])
+		if atomName == name {
+			return i
+		}
+		i += size
+	}
+	return -1
+}
+
+// buildMetaAtom builds a complete meta atom with ilst containing metadata
+func buildMetaAtom(metadata Metadata, coverData []byte) []byte {
+	// Build ilst content
+	var ilst []byte
+
+	// ©nam - Title
+	if metadata.Title != "" {
+		ilst = append(ilst, buildTextAtom("©nam", metadata.Title)...)
+	}
+
+	// ©ART - Artist
+	if metadata.Artist != "" {
+		ilst = append(ilst, buildTextAtom("©ART", metadata.Artist)...)
+	}
+
+	// ©alb - Album
+	if metadata.Album != "" {
+		ilst = append(ilst, buildTextAtom("©alb", metadata.Album)...)
+	}
+
+	// aART - Album Artist
+	if metadata.AlbumArtist != "" {
+		ilst = append(ilst, buildTextAtom("aART", metadata.AlbumArtist)...)
+	}
+
+	// ©day - Year/Date
+	if metadata.Date != "" {
+		ilst = append(ilst, buildTextAtom("©day", metadata.Date)...)
+	}
+
+	// trkn - Track Number
+	if metadata.TrackNumber > 0 {
+		ilst = append(ilst, buildTrackNumberAtom(metadata.TrackNumber, metadata.TotalTracks)...)
+	}
+
+	// disk - Disc Number
+	if metadata.DiscNumber > 0 {
+		ilst = append(ilst, buildDiscNumberAtom(metadata.DiscNumber, 0)...)
+	}
+
+	// ©lyr - Lyrics
+	if metadata.Lyrics != "" {
+		ilst = append(ilst, buildTextAtom("©lyr", metadata.Lyrics)...)
+	}
+
+	// covr - Cover Art
+	if len(coverData) > 0 {
+		ilst = append(ilst, buildCoverAtom(coverData)...)
+	}
+
+	// Build ilst atom
+	ilstSize := 8 + len(ilst)
+	ilstAtom := make([]byte, 4)
+	ilstAtom[0] = byte(ilstSize >> 24)
+	ilstAtom[1] = byte(ilstSize >> 16)
+	ilstAtom[2] = byte(ilstSize >> 8)
+	ilstAtom[3] = byte(ilstSize)
+	ilstAtom = append(ilstAtom, []byte("ilst")...)
+	ilstAtom = append(ilstAtom, ilst...)
+
+	// Build hdlr atom (required for meta)
+	hdlr := []byte{
+		0, 0, 0, 33, // size = 33
+		'h', 'd', 'l', 'r',
+		0, 0, 0, 0, // version + flags
+		0, 0, 0, 0, // predefined
+		'm', 'd', 'i', 'r', // handler type
+		'a', 'p', 'p', 'l', // manufacturer
+		0, 0, 0, 0, // component flags
+		0, 0, 0, 0, // component flags mask
+		0, // null terminator
+	}
+
+	// Build meta atom
+	metaContent := append([]byte{0, 0, 0, 0}, hdlr...) // version + flags + hdlr
+	metaContent = append(metaContent, ilstAtom...)
+
+	metaSize := 8 + len(metaContent)
+	metaAtom := make([]byte, 4)
+	metaAtom[0] = byte(metaSize >> 24)
+	metaAtom[1] = byte(metaSize >> 16)
+	metaAtom[2] = byte(metaSize >> 8)
+	metaAtom[3] = byte(metaSize)
+	metaAtom = append(metaAtom, []byte("meta")...)
+	metaAtom = append(metaAtom, metaContent...)
+
+	return metaAtom
+}
+
+// buildTextAtom builds a text metadata atom (©nam, ©ART, etc.)
+func buildTextAtom(name, value string) []byte {
+	valueBytes := []byte(value)
+
+	// data atom
+	dataSize := 16 + len(valueBytes)
+	dataAtom := make([]byte, 4)
+	dataAtom[0] = byte(dataSize >> 24)
+	dataAtom[1] = byte(dataSize >> 16)
+	dataAtom[2] = byte(dataSize >> 8)
+	dataAtom[3] = byte(dataSize)
+	dataAtom = append(dataAtom, []byte("data")...)
+	dataAtom = append(dataAtom, 0, 0, 0, 1) // type = UTF-8
+	dataAtom = append(dataAtom, 0, 0, 0, 0) // locale
+	dataAtom = append(dataAtom, valueBytes...)
+
+	// container atom
+	atomSize := 8 + len(dataAtom)
+	atom := make([]byte, 4)
+	atom[0] = byte(atomSize >> 24)
+	atom[1] = byte(atomSize >> 16)
+	atom[2] = byte(atomSize >> 8)
+	atom[3] = byte(atomSize)
+	atom = append(atom, []byte(name)...)
+	atom = append(atom, dataAtom...)
+
+	return atom
+}
+
+// buildTrackNumberAtom builds trkn atom
+func buildTrackNumberAtom(track, total int) []byte {
+	// data atom with track number
+	dataAtom := []byte{
+		0, 0, 0, 24, // size
+		'd', 'a', 't', 'a',
+		0, 0, 0, 0, // type = implicit
+		0, 0, 0, 0, // locale
+		0, 0, // padding
+		byte(track >> 8), byte(track), // track number
+		byte(total >> 8), byte(total), // total tracks
+		0, 0, // padding
+	}
+
+	// trkn atom
+	atomSize := 8 + len(dataAtom)
+	atom := make([]byte, 4)
+	atom[0] = byte(atomSize >> 24)
+	atom[1] = byte(atomSize >> 16)
+	atom[2] = byte(atomSize >> 8)
+	atom[3] = byte(atomSize)
+	atom = append(atom, []byte("trkn")...)
+	atom = append(atom, dataAtom...)
+
+	return atom
+}
+
+// buildDiscNumberAtom builds disk atom
+func buildDiscNumberAtom(disc, total int) []byte {
+	// data atom with disc number
+	dataAtom := []byte{
+		0, 0, 0, 22, // size
+		'd', 'a', 't', 'a',
+		0, 0, 0, 0, // type = implicit
+		0, 0, 0, 0, // locale
+		0, 0, // padding
+		byte(disc >> 8), byte(disc), // disc number
+		byte(total >> 8), byte(total), // total discs
+	}
+
+	// disk atom
+	atomSize := 8 + len(dataAtom)
+	atom := make([]byte, 4)
+	atom[0] = byte(atomSize >> 24)
+	atom[1] = byte(atomSize >> 16)
+	atom[2] = byte(atomSize >> 8)
+	atom[3] = byte(atomSize)
+	atom = append(atom, []byte("disk")...)
+	atom = append(atom, dataAtom...)
+
+	return atom
+}
+
+// buildCoverAtom builds covr atom with image data
+func buildCoverAtom(coverData []byte) []byte {
+	// Detect image type (JPEG = 13, PNG = 14)
+	imageType := byte(13) // default JPEG
+	if len(coverData) > 8 && coverData[0] == 0x89 && coverData[1] == 'P' && coverData[2] == 'N' && coverData[3] == 'G' {
+		imageType = 14 // PNG
+	}
+
+	// data atom
+	dataSize := 16 + len(coverData)
+	dataAtom := make([]byte, 4)
+	dataAtom[0] = byte(dataSize >> 24)
+	dataAtom[1] = byte(dataSize >> 16)
+	dataAtom[2] = byte(dataSize >> 8)
+	dataAtom[3] = byte(dataSize)
+	dataAtom = append(dataAtom, []byte("data")...)
+	dataAtom = append(dataAtom, 0, 0, 0, imageType) // type = JPEG or PNG
+	dataAtom = append(dataAtom, 0, 0, 0, 0)         // locale
+	dataAtom = append(dataAtom, coverData...)
+
+	// covr atom
+	atomSize := 8 + len(dataAtom)
+	atom := make([]byte, 4)
+	atom[0] = byte(atomSize >> 24)
+	atom[1] = byte(atomSize >> 16)
+	atom[2] = byte(atomSize >> 8)
+	atom[3] = byte(atomSize)
+	atom = append(atom, []byte("covr")...)
+	atom = append(atom, dataAtom...)
+
+	return atom
+}
+
+// GetM4AQuality reads audio quality from M4A file
+func GetM4AQuality(filePath string) (AudioQuality, error) {
+	data, err := os.ReadFile(filePath)
+	if err != nil {
+		return AudioQuality{}, fmt.Errorf("failed to read M4A file: %w", err)
+	}
+
+	// Find moov -> trak -> mdia -> minf -> stbl -> stsd
+	moovPos := findAtom(data, "moov", 0)
+	if moovPos < 0 {
+		return AudioQuality{}, fmt.Errorf("moov atom not found")
+	}
+
+	// Search for mp4a or alac atom which contains audio info
+	// This is a simplified search - real implementation would traverse the atom tree
+	for i := moovPos; i < len(data)-20; i++ {
+		if string(data[i:i+4]) == "mp4a" || string(data[i:i+4]) == "alac" {
+			// Sample rate is at offset 22-23 from atom start (16-bit big-endian)
+			if i+24 < len(data) {
+				sampleRate := int(data[i+22])<<8 | int(data[i+23])
+				// For AAC, bit depth is typically 16
+				bitDepth := 16
+				if string(data[i:i+4]) == "alac" {
+					// ALAC can have higher bit depth, check esds or alac specific data
+					bitDepth = 24 // Assume 24-bit for ALAC
+				}
+				return AudioQuality{BitDepth: bitDepth, SampleRate: sampleRate}, nil
+			}
+		}
+	}
+
+	return AudioQuality{}, fmt.Errorf("audio info not found in M4A file")
+}

go_backend/parallel.go

@@ -0,0 +1,289 @@
+package gobackend
+
+import (
+	"fmt"
+	"sync"
+	"time"
+)
+
+// ========================================
+// ISRC to Track ID Cache
+// ========================================
+
+// TrackIDCacheEntry holds cached track ID with metadata
+type TrackIDCacheEntry struct {
+	TidalTrackID  int64
+	QobuzTrackID  int64
+	AmazonTrackID string
+	ExpiresAt     time.Time
+}
+
+// TrackIDCache caches ISRC to track ID mappings
+type TrackIDCache struct {
+	cache map[string]*TrackIDCacheEntry
+	mu    sync.RWMutex
+	ttl   time.Duration
+}
+
+var (
+	globalTrackIDCache *TrackIDCache
+	trackIDCacheOnce   sync.Once
+)
+
+// GetTrackIDCache returns the global track ID cache
+func GetTrackIDCache() *TrackIDCache {
+	trackIDCacheOnce.Do(func() {
+		globalTrackIDCache = &TrackIDCache{
+			cache: make(map[string]*TrackIDCacheEntry),
+			ttl:   30 * time.Minute, // Cache for 30 minutes
+		}
+	})
+	return globalTrackIDCache
+}
+
+// Get retrieves a cached entry by ISRC
+func (c *TrackIDCache) Get(isrc string) *TrackIDCacheEntry {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
+	entry, exists := c.cache[isrc]
+	if !exists || time.Now().After(entry.ExpiresAt) {
+		return nil
+	}
+	return entry
+}
+
+// SetTidal caches Tidal track ID for an ISRC
+func (c *TrackIDCache) SetTidal(isrc string, trackID int64) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	entry, exists := c.cache[isrc]
+	if !exists {
+		entry = &TrackIDCacheEntry{}
+		c.cache[isrc] = entry
+	}
+	entry.TidalTrackID = trackID
+	entry.ExpiresAt = time.Now().Add(c.ttl)
+}
+
+// SetQobuz caches Qobuz track ID for an ISRC
+func (c *TrackIDCache) SetQobuz(isrc string, trackID int64) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	entry, exists := c.cache[isrc]
+	if !exists {
+		entry = &TrackIDCacheEntry{}
+		c.cache[isrc] = entry
+	}
+	entry.QobuzTrackID = trackID
+	entry.ExpiresAt = time.Now().Add(c.ttl)
+}
+
+// SetAmazon caches Amazon track ID for an ISRC
+func (c *TrackIDCache) SetAmazon(isrc string, trackID string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	entry, exists := c.cache[isrc]
+	if !exists {
+		entry = &TrackIDCacheEntry{}
+		c.cache[isrc] = entry
+	}
+	entry.AmazonTrackID = trackID
+	entry.ExpiresAt = time.Now().Add(c.ttl)
+}
+
+// Clear removes all cached entries
+func (c *TrackIDCache) Clear() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.cache = make(map[string]*TrackIDCacheEntry)
+}
+
+// Size returns the number of cached entries
+func (c *TrackIDCache) Size() int {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	return len(c.cache)
+}
+
+// ========================================
+// Parallel Download Helper
+// ========================================
+
+// ParallelDownloadResult holds results from parallel operations
+type ParallelDownloadResult struct {
+	CoverData  []byte
+	LyricsData *LyricsResponse
+	LyricsLRC  string
+	CoverErr   error
+	LyricsErr  error
+}
+
+// FetchCoverAndLyricsParallel downloads cover and fetches lyrics in parallel
+// This runs while the main audio download is happening
+func FetchCoverAndLyricsParallel(
+	coverURL string,
+	maxQualityCover bool,
+	spotifyID string,
+	trackName string,
+	artistName string,
+	embedLyrics bool,
+) *ParallelDownloadResult {
+	result := &ParallelDownloadResult{}
+	var wg sync.WaitGroup
+
+	// Download cover in parallel
+	if coverURL != "" {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			fmt.Println("[Parallel] Starting cover download...")
+			data, err := downloadCoverToMemory(coverURL, maxQualityCover)
+			if err != nil {
+				result.CoverErr = err
+				fmt.Printf("[Parallel] Cover download failed: %v\n", err)
+			} else {
+				result.CoverData = data
+				fmt.Printf("[Parallel] Cover downloaded: %d bytes\n", len(data))
+			}
+		}()
+	}
+
+	// Fetch lyrics in parallel
+	if embedLyrics {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			fmt.Println("[Parallel] Starting lyrics fetch...")
+			client := NewLyricsClient()
+			lyrics, err := client.FetchLyricsAllSources(spotifyID, trackName, artistName)
+			if err != nil {
+				result.LyricsErr = err
+				fmt.Printf("[Parallel] Lyrics fetch failed: %v\n", err)
+			} else if lyrics != nil && len(lyrics.Lines) > 0 {
+				result.LyricsData = lyrics
+				// Use LRC with metadata headers (like PC version)
+				result.LyricsLRC = convertToLRCWithMetadata(lyrics, trackName, artistName)
+				fmt.Printf("[Parallel] Lyrics fetched: %d lines\n", len(lyrics.Lines))
+			} else {
+				result.LyricsErr = fmt.Errorf("no lyrics found")
+				fmt.Println("[Parallel] No lyrics found")
+			}
+		}()
+	}
+
+	wg.Wait()
+	return result
+}
+
+// ========================================
+// Pre-warm Cache for Album/Playlist
+// ========================================
+
+// PreWarmCacheRequest represents a track to pre-warm cache for
+type PreWarmCacheRequest struct {
+	ISRC       string
+	TrackName  string
+	ArtistName string
+	SpotifyID  string // Needed for Amazon (SongLink lookup)
+	Service    string // "tidal", "qobuz", "amazon"
+}
+
+// PreWarmTrackCache pre-fetches track IDs for multiple tracks (for album/playlist)
+// This runs in background while user is viewing the track list
+func PreWarmTrackCache(requests []PreWarmCacheRequest) {
+	if len(requests) == 0 {
+		return
+	}
+
+	fmt.Printf("[Cache] Pre-warming cache for %d tracks...\n", len(requests))
+	cache := GetTrackIDCache()
+
+	// Limit concurrent pre-warm requests
+	semaphore := make(chan struct{}, 3) // Max 3 concurrent
+	var wg sync.WaitGroup
+
+	for _, req := range requests {
+		// Skip if already cached
+		if cached := cache.Get(req.ISRC); cached != nil {
+			continue
+		}
+
+		wg.Add(1)
+		go func(r PreWarmCacheRequest) {
+			defer wg.Done()
+			semaphore <- struct{}{}        // Acquire
+			defer func() { <-semaphore }() // Release
+
+			switch r.Service {
+			case "tidal":
+				preWarmTidalCache(r.ISRC, r.TrackName, r.ArtistName)
+			case "qobuz":
+				preWarmQobuzCache(r.ISRC)
+			case "amazon":
+				preWarmAmazonCache(r.ISRC, r.SpotifyID)
+			}
+		}(req)
+	}
+
+	wg.Wait()
+	fmt.Printf("[Cache] Pre-warm complete. Cache size: %d\n", cache.Size())
+}
+
+func preWarmTidalCache(isrc, _, _ string) {
+	downloader := NewTidalDownloader()
+	track, err := downloader.SearchTrackByISRC(isrc)
+	if err == nil && track != nil {
+		GetTrackIDCache().SetTidal(isrc, track.ID)
+		fmt.Printf("[Cache] Cached Tidal ID for ISRC %s: %d\n", isrc, track.ID)
+	}
+}
+
+func preWarmQobuzCache(isrc string) {
+	downloader := NewQobuzDownloader()
+	track, err := downloader.SearchTrackByISRC(isrc)
+	if err == nil && track != nil {
+		GetTrackIDCache().SetQobuz(isrc, track.ID)
+		fmt.Printf("[Cache] Cached Qobuz ID for ISRC %s: %d\n", isrc, track.ID)
+	}
+}
+
+func preWarmAmazonCache(isrc, spotifyID string) {
+	// Amazon uses SongLink to get URL, so we pre-warm by checking availability
+	client := NewSongLinkClient()
+	availability, err := client.CheckTrackAvailability(spotifyID, isrc)
+	if err == nil && availability != nil && availability.Amazon {
+		// Store Amazon URL in cache (using ISRC as key)
+		GetTrackIDCache().SetAmazon(isrc, availability.AmazonURL)
+		fmt.Printf("[Cache] Cached Amazon URL for ISRC %s\n", isrc)
+	}
+}
+
+// ========================================
+// Exported Functions for Flutter
+// ========================================
+
+// PreWarmCache is called from Flutter to pre-warm cache for album/playlist tracks
+// tracksJSON is a JSON array of {isrc, track_name, artist_name, service}
+func PreWarmCache(tracksJSON string) error {
+	var requests []PreWarmCacheRequest
+	// Parse JSON (simplified - in production use proper JSON parsing)
+	// For now, this is called from exports.go with proper parsing
+
+	go PreWarmTrackCache(requests) // Run in background
+	return nil
+}
+
+// ClearTrackCache clears the track ID cache
+func ClearTrackCache() {
+	GetTrackIDCache().Clear()
+	fmt.Println("[Cache] Track ID cache cleared")
+}
+
+// GetCacheSize returns the current cache size
+func GetCacheSize() int {
+	return GetTrackIDCache().Size()
+}

go_backend/progress.go

@@ -3,9 +3,11 @@ package gobackend
 import (
 	"encoding/json"
 	"sync"
+	"time"
 )
 
-// DownloadProgress represents current download progress (legacy single download)
+// DownloadProgress represents current download progress
+// Now unified - returns data from multi-progress system
 type DownloadProgress struct {
 	CurrentFile   string  `json:"current_file"`
 	Progress      float64 `json:"progress"`
@@ -13,6 +15,7 @@ type DownloadProgress struct {
 	BytesTotal    int64   `json:"bytes_total"`
 	BytesReceived int64   `json:"bytes_received"`
 	IsDownloading bool    `json:"is_downloading"`
+	Status        string  `json:"status"` // "downloading", "finalizing", "completed"
 }
 
 // ItemProgress represents progress for a single download item
@@ -20,8 +23,10 @@ type ItemProgress struct {
 	ItemID        string  `json:"item_id"`
 	BytesTotal    int64   `json:"bytes_total"`
 	BytesReceived int64   `json:"bytes_received"`
-	Progress      float64 `json:"progress"` // 0.0 to 1.0
+	Progress      float64 `json:"progress"`   // 0.0 to 1.0
+	SpeedMBps     float64 `json:"speed_mbps"` // Download speed in MB/s
 	IsDownloading bool    `json:"is_downloading"`
+	Status        string  `json:"status"` // "downloading", "finalizing", "completed"
 }
 
 // MultiProgress holds progress for multiple concurrent downloads
@@ -30,28 +35,40 @@ type MultiProgress struct {
 }
 
 var (
-	currentProgress DownloadProgress
-	progressMu      sync.RWMutex
-	downloadDir     string
-	downloadDirMu   sync.RWMutex
-	
-	// Multi-download progress tracking
+	downloadDir   string
+	downloadDirMu sync.RWMutex
+
+	// Multi-download progress tracking (unified system)
 	multiProgress = MultiProgress{Items: make(map[string]*ItemProgress)}
 	multiMu       sync.RWMutex
 )
 
-// getProgress returns current download progress (legacy)
+// getProgress returns current download progress from multi-progress system
+// Returns first active item's progress for backward compatibility
 func getProgress() DownloadProgress {
-	progressMu.RLock()
-	defer progressMu.RUnlock()
-	return currentProgress
+	multiMu.RLock()
+	defer multiMu.RUnlock()
+
+	// Find first active item
+	for _, item := range multiProgress.Items {
+		return DownloadProgress{
+			CurrentFile:   item.ItemID,
+			Progress:      item.Progress * 100, // Convert to percentage
+			BytesTotal:    item.BytesTotal,
+			BytesReceived: item.BytesReceived,
+			IsDownloading: item.IsDownloading,
+			Status:        item.Status,
+		}
+	}
+
+	return DownloadProgress{}
 }
 
 // GetMultiProgress returns progress for all active downloads as JSON
 func GetMultiProgress() string {
 	multiMu.RLock()
 	defer multiMu.RUnlock()
-	
+
 	jsonBytes, err := json.Marshal(multiProgress)
 	if err != nil {
 		return "{\"items\":{}}"
@@ -63,7 +80,7 @@ func GetMultiProgress() string {
 func GetItemProgress(itemID string) string {
 	multiMu.RLock()
 	defer multiMu.RUnlock()
-	
+
 	if item, ok := multiProgress.Items[itemID]; ok {
 		jsonBytes, _ := json.Marshal(item)
 		return string(jsonBytes)
@@ -75,13 +92,14 @@ func GetItemProgress(itemID string) string {
 func StartItemProgress(itemID string) {
 	multiMu.Lock()
 	defer multiMu.Unlock()
-	
+
 	multiProgress.Items[itemID] = &ItemProgress{
 		ItemID:        itemID,
 		BytesTotal:    0,
 		BytesReceived: 0,
 		Progress:      0,
 		IsDownloading: true,
+		Status:        "downloading",
 	}
 }
 
@@ -89,7 +107,7 @@ func StartItemProgress(itemID string) {
 func SetItemBytesTotal(itemID string, total int64) {
 	multiMu.Lock()
 	defer multiMu.Unlock()
-	
+
 	if item, ok := multiProgress.Items[itemID]; ok {
 		item.BytesTotal = total
 	}
@@ -99,7 +117,7 @@ func SetItemBytesTotal(itemID string, total int64) {
 func SetItemBytesReceived(itemID string, received int64) {
 	multiMu.Lock()
 	defer multiMu.Unlock()
-	
+
 	if item, ok := multiProgress.Items[itemID]; ok {
 		item.BytesReceived = received
 		if item.BytesTotal > 0 {
@@ -108,14 +126,56 @@ func SetItemBytesReceived(itemID string, received int64) {
 	}
 }
 
+// SetItemBytesReceivedWithSpeed sets bytes received and speed for an item
+func SetItemBytesReceivedWithSpeed(itemID string, received int64, speedMBps float64) {
+	multiMu.Lock()
+	defer multiMu.Unlock()
+
+	if item, ok := multiProgress.Items[itemID]; ok {
+		item.BytesReceived = received
+		item.SpeedMBps = speedMBps
+		if item.BytesTotal > 0 {
+			item.Progress = float64(received) / float64(item.BytesTotal)
+		}
+	}
+}
+
 // CompleteItemProgress marks an item as complete
 func CompleteItemProgress(itemID string) {
 	multiMu.Lock()
 	defer multiMu.Unlock()
-	
+
 	if item, ok := multiProgress.Items[itemID]; ok {
 		item.Progress = 1.0
 		item.IsDownloading = false
+		item.Status = "completed"
+	}
+}
+
+// SetItemProgress sets progress for an item directly
+func SetItemProgress(itemID string, progress float64, bytesReceived, bytesTotal int64) {
+	multiMu.Lock()
+	defer multiMu.Unlock()
+
+	if item, ok := multiProgress.Items[itemID]; ok {
+		item.Progress = progress
+		if bytesReceived > 0 {
+			item.BytesReceived = bytesReceived
+		}
+		if bytesTotal > 0 {
+			item.BytesTotal = bytesTotal
+		}
+	}
+}
+
+// SetItemFinalizing marks an item as finalizing (embedding metadata)
+func SetItemFinalizing(itemID string) {
+	multiMu.Lock()
+	defer multiMu.Unlock()
+
+	if item, ok := multiProgress.Items[itemID]; ok {
+		item.Progress = 1.0
+		item.Status = "finalizing"
 	}
 }
 
@@ -123,7 +183,7 @@ func CompleteItemProgress(itemID string) {
 func RemoveItemProgress(itemID string) {
 	multiMu.Lock()
 	defer multiMu.Unlock()
-	
+
 	delete(multiProgress.Items, itemID)
 }
 
@@ -131,45 +191,10 @@ func RemoveItemProgress(itemID string) {
 func ClearAllItemProgress() {
 	multiMu.Lock()
 	defer multiMu.Unlock()
-	
+
 	multiProgress.Items = make(map[string]*ItemProgress)
 }
 
-// Legacy functions for backward compatibility
-
-// SetDownloadProgress sets the current download progress (MB downloaded)
-func SetDownloadProgress(mbDownloaded float64) {
-	progressMu.Lock()
-	defer progressMu.Unlock()
-	currentProgress.Progress = mbDownloaded
-	currentProgress.IsDownloading = true
-}
-
-// SetDownloadSpeed sets the current download speed
-func SetDownloadSpeed(speedMBps float64) {
-	progressMu.Lock()
-	defer progressMu.Unlock()
-	currentProgress.Speed = speedMBps
-}
-
-// SetCurrentFile sets the current file being downloaded and resets progress
-func SetCurrentFile(filename string) {
-	progressMu.Lock()
-	defer progressMu.Unlock()
-	currentProgress.BytesReceived = 0
-	currentProgress.BytesTotal = 0
-	currentProgress.Progress = 0
-	currentProgress.CurrentFile = filename
-	currentProgress.IsDownloading = true
-}
-
-// ResetProgress resets the download progress
-func ResetProgress() {
-	progressMu.Lock()
-	defer progressMu.Unlock()
-	currentProgress = DownloadProgress{}
-}
-
 // setDownloadDir sets the default download directory
 func setDownloadDir(path string) error {
 	downloadDirMu.Lock()
@@ -179,95 +204,64 @@ func setDownloadDir(path string) error {
 }
 
 // getDownloadDir returns the default download directory
-func getDownloadDir() string {
-	downloadDirMu.RLock()
-	defer downloadDirMu.RUnlock()
-	return downloadDir
-}
-
-// SetDownloading sets the download status
-func SetDownloading(status bool) {
-	progressMu.Lock()
-	defer progressMu.Unlock()
-	currentProgress.IsDownloading = status
-}
-
-// SetBytesTotal sets total bytes to download
-func SetBytesTotal(total int64) {
-	progressMu.Lock()
-	defer progressMu.Unlock()
-	currentProgress.BytesTotal = total
-}
-
-// SetBytesReceived sets bytes received so far
-func SetBytesReceived(received int64) {
-	progressMu.Lock()
-	defer progressMu.Unlock()
-	currentProgress.BytesReceived = received
-	if currentProgress.BytesTotal > 0 {
-		currentProgress.Progress = float64(received) / float64(currentProgress.BytesTotal) * 100
-	}
-}
-
-// ProgressWriter wraps io.Writer to track download progress (legacy single)
-type ProgressWriter struct {
-	writer  interface{ Write([]byte) (int, error) }
-	total   int64
-	current int64
-}
-
-// NewProgressWriter creates a new progress writer wrapping an io.Writer
-func NewProgressWriter(w interface{ Write([]byte) (int, error) }) *ProgressWriter {
-	SetBytesReceived(0)
-	return &ProgressWriter{
-		writer:  w,
-		current: 0,
-		total:   0,
-	}
-}
-
-// Write implements io.Writer
-func (pw *ProgressWriter) Write(p []byte) (int, error) {
-	n, err := pw.writer.Write(p)
-	if err != nil {
-		return n, err
-	}
-	pw.current += int64(n)
-	pw.total += int64(n)
-	SetBytesReceived(pw.current)
-	return n, nil
-}
-
-// GetTotal returns total bytes written
-func (pw *ProgressWriter) GetTotal() int64 {
-	return pw.total
-}
+// Kept for potential future use
+// func getDownloadDir() string {
+// 	downloadDirMu.RLock()
+// 	defer downloadDirMu.RUnlock()
+// 	return downloadDir
+// }
 
 // ItemProgressWriter wraps io.Writer to track download progress for a specific item
 type ItemProgressWriter struct {
-	writer  interface{ Write([]byte) (int, error) }
-	itemID  string
-	current int64
+	writer       interface{ Write([]byte) (int, error) }
+	itemID       string
+	current      int64
+	lastReported int64     // Track last reported bytes for threshold-based updates
+	startTime    time.Time // Track start time for speed calculation
+	lastTime     time.Time // Track last update time for speed calculation
+	lastBytes    int64     // Track bytes at last speed calculation
 }
 
+const progressUpdateThreshold = 64 * 1024 // Update progress every 64KB
+
 // NewItemProgressWriter creates a new progress writer for a specific item
 func NewItemProgressWriter(w interface{ Write([]byte) (int, error) }, itemID string) *ItemProgressWriter {
+	now := time.Now()
 	return &ItemProgressWriter{
-		writer:  w,
-		itemID:  itemID,
-		current: 0,
+		writer:       w,
+		itemID:       itemID,
+		current:      0,
+		lastReported: 0,
+		startTime:    now,
+		lastTime:     now,
+		lastBytes:    0,
 	}
 }
 
-// Write implements io.Writer
+// Write implements io.Writer with threshold-based progress updates and speed tracking
 func (pw *ItemProgressWriter) Write(p []byte) (int, error) {
 	n, err := pw.writer.Write(p)
 	if err != nil {
 		return n, err
 	}
 	pw.current += int64(n)
-	SetItemBytesReceived(pw.itemID, pw.current)
-	// Also update legacy progress for backward compatibility
-	SetBytesReceived(pw.current)
+
+	// Update progress when we've received at least 64KB since last update
+	// Also update on first write to show download has started
+	if pw.lastReported == 0 || pw.current-pw.lastReported >= progressUpdateThreshold {
+		// Calculate speed (MB/s) based on bytes received since last update
+		now := time.Now()
+		elapsed := now.Sub(pw.lastTime).Seconds()
+		var speedMBps float64
+		if elapsed > 0 {
+			bytesInInterval := pw.current - pw.lastBytes
+			speedMBps = float64(bytesInInterval) / (1024 * 1024) / elapsed
+		}
+
+		SetItemBytesReceivedWithSpeed(pw.itemID, pw.current, speedMBps)
+		pw.lastReported = pw.current
+		pw.lastTime = now
+		pw.lastBytes = pw.current
+	}
 	return n, nil
 }

go_backend/qobuz.go

@@ -1,6 +1,7 @@
 package gobackend
 
 import (
+	"bufio"
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
@@ -9,6 +10,8 @@ import (
 	"net/url"
 	"os"
 	"path/filepath"
+	"strings"
+	"sync"
 )
 
 // QobuzDownloader handles Qobuz downloads
@@ -18,6 +21,12 @@ type QobuzDownloader struct {
 	apiURL string
 }
 
+var (
+	// Global Qobuz downloader instance for connection reuse
+	globalQobuzDownloader *QobuzDownloader
+	qobuzDownloaderOnce   sync.Once
+)
+
 // QobuzTrack represents a Qobuz track
 type QobuzTrack struct {
 	ID                  int64   `json:"id"`
@@ -39,12 +48,258 @@ type QobuzTrack struct {
 	} `json:"performer"`
 }
 
-// NewQobuzDownloader creates a new Qobuz downloader
-func NewQobuzDownloader() *QobuzDownloader {
-	return &QobuzDownloader{
-		client: NewHTTPClientWithTimeout(DefaultTimeout), // 60s timeout
-		appID:  "798273057",
+// qobuzArtistsMatch checks if the artist names are similar enough
+func qobuzArtistsMatch(expectedArtist, foundArtist string) bool {
+	normExpected := strings.ToLower(strings.TrimSpace(expectedArtist))
+	normFound := strings.ToLower(strings.TrimSpace(foundArtist))
+
+	// Exact match
+	if normExpected == normFound {
+		return true
 	}
+
+	// Check if one contains the other
+	if strings.Contains(normExpected, normFound) || strings.Contains(normFound, normExpected) {
+		return true
+	}
+
+	// Check first artist (before comma or feat)
+	expectedFirst := strings.Split(normExpected, ",")[0]
+	expectedFirst = strings.Split(expectedFirst, " feat")[0]
+	expectedFirst = strings.Split(expectedFirst, " ft.")[0]
+	expectedFirst = strings.TrimSpace(expectedFirst)
+
+	foundFirst := strings.Split(normFound, ",")[0]
+	foundFirst = strings.Split(foundFirst, " feat")[0]
+	foundFirst = strings.Split(foundFirst, " ft.")[0]
+	foundFirst = strings.TrimSpace(foundFirst)
+
+	if expectedFirst == foundFirst {
+		return true
+	}
+
+	// Check if first artist is contained in the other
+	if strings.Contains(expectedFirst, foundFirst) || strings.Contains(foundFirst, expectedFirst) {
+		return true
+	}
+
+	// If scripts are TRULY different (Latin vs CJK/Arabic/Cyrillic), assume match (transliteration)
+	// Don't treat Latin Extended (Polish, French, etc.) as different script
+	expectedLatin := qobuzIsLatinScript(expectedArtist)
+	foundLatin := qobuzIsLatinScript(foundArtist)
+	if expectedLatin != foundLatin {
+		GoLog("[Qobuz] Artist names in different scripts, assuming match: '%s' vs '%s'\n", expectedArtist, foundArtist)
+		return true
+	}
+
+	return false
+}
+
+// qobuzTitlesMatch checks if track titles are similar enough
+func qobuzTitlesMatch(expectedTitle, foundTitle string) bool {
+	normExpected := strings.ToLower(strings.TrimSpace(expectedTitle))
+	normFound := strings.ToLower(strings.TrimSpace(foundTitle))
+
+	// Exact match
+	if normExpected == normFound {
+		return true
+	}
+
+	// Check if one contains the other
+	if strings.Contains(normExpected, normFound) || strings.Contains(normFound, normExpected) {
+		return true
+	}
+
+	// Clean BOTH titles and compare (removes suffixes like remaster, remix, etc)
+	cleanExpected := qobuzCleanTitle(normExpected)
+	cleanFound := qobuzCleanTitle(normFound)
+
+	if cleanExpected == cleanFound {
+		return true
+	}
+
+	// Check if cleaned versions contain each other
+	if cleanExpected != "" && cleanFound != "" {
+		if strings.Contains(cleanExpected, cleanFound) || strings.Contains(cleanFound, cleanExpected) {
+			return true
+		}
+	}
+
+	// Extract core title (before any parentheses/brackets)
+	coreExpected := qobuzExtractCoreTitle(normExpected)
+	coreFound := qobuzExtractCoreTitle(normFound)
+
+	if coreExpected != "" && coreFound != "" && coreExpected == coreFound {
+		return true
+	}
+
+	// If scripts are TRULY different (Latin vs CJK/Arabic/Cyrillic), assume match (transliteration)
+	// Don't treat Latin Extended (Polish, French, etc.) as different script
+	expectedLatin := qobuzIsLatinScript(expectedTitle)
+	foundLatin := qobuzIsLatinScript(foundTitle)
+	if expectedLatin != foundLatin {
+		GoLog("[Qobuz] Titles in different scripts, assuming match: '%s' vs '%s'\n", expectedTitle, foundTitle)
+		return true
+	}
+
+	return false
+}
+
+// qobuzExtractCoreTitle extracts the main title before any parentheses or brackets
+func qobuzExtractCoreTitle(title string) string {
+	// Find first occurrence of ( or [
+	parenIdx := strings.Index(title, "(")
+	bracketIdx := strings.Index(title, "[")
+	dashIdx := strings.Index(title, " - ")
+
+	cutIdx := len(title)
+	if parenIdx > 0 && parenIdx < cutIdx {
+		cutIdx = parenIdx
+	}
+	if bracketIdx > 0 && bracketIdx < cutIdx {
+		cutIdx = bracketIdx
+	}
+	if dashIdx > 0 && dashIdx < cutIdx {
+		cutIdx = dashIdx
+	}
+
+	return strings.TrimSpace(title[:cutIdx])
+}
+
+// qobuzCleanTitle removes common suffixes from track titles for comparison
+func qobuzCleanTitle(title string) string {
+	cleaned := title
+
+	// Remove content in parentheses/brackets that are version indicators
+	// This helps match "Song (Remastered)" with "Song" or "Song (2024 Remaster)"
+	versionPatterns := []string{
+		"remaster", "remastered", "deluxe", "bonus", "single",
+		"album version", "radio edit", "original mix", "extended",
+		"club mix", "remix", "live", "acoustic", "demo",
+	}
+
+	// Remove parenthetical content if it contains version indicators
+	for {
+		startParen := strings.LastIndex(cleaned, "(")
+		endParen := strings.LastIndex(cleaned, ")")
+		if startParen >= 0 && endParen > startParen {
+			content := strings.ToLower(cleaned[startParen+1 : endParen])
+			isVersionIndicator := false
+			for _, pattern := range versionPatterns {
+				if strings.Contains(content, pattern) {
+					isVersionIndicator = true
+					break
+				}
+			}
+			if isVersionIndicator {
+				cleaned = strings.TrimSpace(cleaned[:startParen]) + cleaned[endParen+1:]
+				continue
+			}
+		}
+		break
+	}
+
+	// Same for brackets
+	for {
+		startBracket := strings.LastIndex(cleaned, "[")
+		endBracket := strings.LastIndex(cleaned, "]")
+		if startBracket >= 0 && endBracket > startBracket {
+			content := strings.ToLower(cleaned[startBracket+1 : endBracket])
+			isVersionIndicator := false
+			for _, pattern := range versionPatterns {
+				if strings.Contains(content, pattern) {
+					isVersionIndicator = true
+					break
+				}
+			}
+			if isVersionIndicator {
+				cleaned = strings.TrimSpace(cleaned[:startBracket]) + cleaned[endBracket+1:]
+				continue
+			}
+		}
+		break
+	}
+
+	// Remove trailing " - version" patterns
+	dashPatterns := []string{
+		" - remaster", " - remastered", " - single version", " - radio edit",
+		" - live", " - acoustic", " - demo", " - remix",
+	}
+	for _, pattern := range dashPatterns {
+		if strings.HasSuffix(strings.ToLower(cleaned), pattern) {
+			cleaned = cleaned[:len(cleaned)-len(pattern)]
+		}
+	}
+
+	// Remove multiple spaces
+	for strings.Contains(cleaned, "  ") {
+		cleaned = strings.ReplaceAll(cleaned, "  ", " ")
+	}
+
+	return strings.TrimSpace(cleaned)
+}
+
+// qobuzIsLatinScript checks if a string is primarily Latin script
+// Returns true for ASCII and Latin Extended characters (European languages)
+// Returns false for CJK, Arabic, Cyrillic, etc.
+func qobuzIsLatinScript(s string) bool {
+	for _, r := range s {
+		// Skip common punctuation and numbers
+		if r < 128 {
+			continue
+		}
+		// Latin Extended-A: U+0100 to U+017F (Polish, Czech, etc.)
+		// Latin Extended-B: U+0180 to U+024F
+		// Latin Extended Additional: U+1E00 to U+1EFF
+		// Latin Extended-C/D/E: various ranges
+		if (r >= 0x0100 && r <= 0x024F) || // Latin Extended A & B
+			(r >= 0x1E00 && r <= 0x1EFF) || // Latin Extended Additional
+			(r >= 0x00C0 && r <= 0x00FF) { // Latin-1 Supplement (accented chars)
+			continue
+		}
+		// CJK ranges - definitely different script
+		if (r >= 0x4E00 && r <= 0x9FFF) || // CJK Unified Ideographs
+			(r >= 0x3040 && r <= 0x309F) || // Hiragana
+			(r >= 0x30A0 && r <= 0x30FF) || // Katakana
+			(r >= 0xAC00 && r <= 0xD7AF) || // Hangul (Korean)
+			(r >= 0x0600 && r <= 0x06FF) || // Arabic
+			(r >= 0x0400 && r <= 0x04FF) { // Cyrillic
+			return false
+		}
+	}
+	return true
+}
+
+// qobuzIsASCIIString checks if a string contains only ASCII characters
+// Kept for potential future use
+// func qobuzIsASCIIString(s string) bool {
+// 	for _, r := range s {
+// 		if r > 127 {
+// 			return false
+// 		}
+// 	}
+// 	return true
+// }
+
+// containsQueryQobuz checks if a query already exists in the list
+func containsQueryQobuz(queries []string, query string) bool {
+	for _, q := range queries {
+		if q == query {
+			return true
+		}
+	}
+	return false
+}
+
+// NewQobuzDownloader creates a new Qobuz downloader (returns singleton for connection reuse)
+func NewQobuzDownloader() *QobuzDownloader {
+	qobuzDownloaderOnce.Do(func() {
+		globalQobuzDownloader = &QobuzDownloader{
+			client: NewHTTPClientWithTimeout(DefaultTimeout), // 60s timeout
+			appID:  "798273057",
+		}
+	})
+	return globalQobuzDownloader
 }
 
 // GetAvailableAPIs returns list of available Qobuz APIs
@@ -53,8 +308,8 @@ func (q *QobuzDownloader) GetAvailableAPIs() []string {
 	// Same APIs as PC version (referensi/backend/qobuz.go)
 	// Primary: dab.yeet.su, Fallback: dabmusic.xyz
 	encodedAPIs := []string{
-		"ZGFiLnllZXQuc3UvYXBpL3N0cmVhbT90cmFja0lkPQ==",     // dab.yeet.su/api/stream?trackId= (PRIMARY - same as PC)
-		"ZGFibXVzaWMueHl6L2FwaS9zdHJlYW0/dHJhY2tJZD0=",     // dabmusic.xyz/api/stream?trackId= (FALLBACK - same as PC)
+		"ZGFiLnllZXQuc3UvYXBpL3N0cmVhbT90cmFja0lkPQ==", // dab.yeet.su/api/stream?trackId= (PRIMARY - same as PC)
+		"ZGFibXVzaWMueHl6L2FwaS9zdHJlYW0/dHJhY2tJZD0=", // dabmusic.xyz/api/stream?trackId= (FALLBACK - same as PC)
 	}
 
 	var apis []string
@@ -112,11 +367,107 @@ func (q *QobuzDownloader) SearchTrackByISRC(isrc string) (*QobuzTrack, error) {
 	return nil, fmt.Errorf("no exact ISRC match found for: %s", isrc)
 }
 
+// SearchTrackByISRCWithTitle searches for a track by ISRC with duration verification
+// expectedDurationSec is the expected duration in seconds (0 to skip verification)
+func (q *QobuzDownloader) SearchTrackByISRCWithDuration(isrc string, expectedDurationSec int) (*QobuzTrack, error) {
+	GoLog("[Qobuz] Searching by ISRC: %s\n", isrc)
+
+	apiBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly93d3cucW9idXouY29tL2FwaS5qc29uLzAuMi90cmFjay9zZWFyY2g/cXVlcnk9")
+	searchURL := fmt.Sprintf("%s%s&limit=50&app_id=%s", string(apiBase), url.QueryEscape(isrc), q.appID)
+
+	req, err := http.NewRequest("GET", searchURL, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := DoRequestWithUserAgent(q.client, req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("search failed: HTTP %d", resp.StatusCode)
+	}
+
+	var result struct {
+		Tracks struct {
+			Items []QobuzTrack `json:"items"`
+		} `json:"tracks"`
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
+		return nil, err
+	}
+
+	GoLog("[Qobuz] ISRC search returned %d results\n", len(result.Tracks.Items))
+
+	// Find ISRC matches
+	var isrcMatches []*QobuzTrack
+	for i := range result.Tracks.Items {
+		if result.Tracks.Items[i].ISRC == isrc {
+			isrcMatches = append(isrcMatches, &result.Tracks.Items[i])
+		}
+	}
+
+	GoLog("[Qobuz] Found %d exact ISRC matches\n", len(isrcMatches))
+
+	if len(isrcMatches) > 0 {
+		// Verify duration if provided
+		if expectedDurationSec > 0 {
+			var durationVerifiedMatches []*QobuzTrack
+			for _, track := range isrcMatches {
+				durationDiff := track.Duration - expectedDurationSec
+				if durationDiff < 0 {
+					durationDiff = -durationDiff
+				}
+				// Allow 10 seconds tolerance
+				if durationDiff <= 10 {
+					durationVerifiedMatches = append(durationVerifiedMatches, track)
+				}
+			}
+
+			if len(durationVerifiedMatches) > 0 {
+				GoLog("[Qobuz] ISRC match with duration verification: '%s' (expected %ds, found %ds)\n",
+					durationVerifiedMatches[0].Title, expectedDurationSec, durationVerifiedMatches[0].Duration)
+				return durationVerifiedMatches[0], nil
+			}
+
+			// ISRC matches but duration doesn't
+			GoLog("[Qobuz] WARNING: ISRC %s found but duration mismatch. Expected=%ds, Found=%ds. Rejecting.\n",
+				isrc, expectedDurationSec, isrcMatches[0].Duration)
+			return nil, fmt.Errorf("ISRC found but duration mismatch: expected %ds, found %ds (likely different version)",
+				expectedDurationSec, isrcMatches[0].Duration)
+		}
+
+		// No duration to verify, return first match
+		GoLog("[Qobuz] ISRC match (no duration verification): '%s'\n", isrcMatches[0].Title)
+		return isrcMatches[0], nil
+	}
+
+	if len(result.Tracks.Items) == 0 {
+		return nil, fmt.Errorf("no tracks found for ISRC: %s", isrc)
+	}
+
+	return nil, fmt.Errorf("no exact ISRC match found for: %s", isrc)
+}
+
+// SearchTrackByISRCWithTitle is deprecated, use SearchTrackByISRCWithDuration instead
+func (q *QobuzDownloader) SearchTrackByISRCWithTitle(isrc, expectedTitle string) (*QobuzTrack, error) {
+	return q.SearchTrackByISRCWithDuration(isrc, 0)
+}
+
 // SearchTrackByMetadata searches for a track using artist name and track name
 func (q *QobuzDownloader) SearchTrackByMetadata(trackName, artistName string) (*QobuzTrack, error) {
+	return q.SearchTrackByMetadataWithDuration(trackName, artistName, 0)
+}
+
+// SearchTrackByMetadataWithDuration searches for a track with duration verification
+// Now includes romaji conversion for Japanese text (same as Tidal)
+// Also includes title verification to prevent wrong song downloads
+func (q *QobuzDownloader) SearchTrackByMetadataWithDuration(trackName, artistName string, expectedDurationSec int) (*QobuzTrack, error) {
 	apiBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly93d3cucW9idXouY29tL2FwaS5qc29uLzAuMi90cmFjay9zZWFyY2g/cXVlcnk9")
 
-	// Try multiple search strategies
+	// Try multiple search strategies (same as Tidal/PC version)
 	queries := []string{}
 
 	// Strategy 1: Artist + Track name
@@ -129,8 +480,54 @@ func (q *QobuzDownloader) SearchTrackByMetadata(trackName, artistName string) (*
 		queries = append(queries, trackName)
 	}
 
+	// Strategy 3: Romaji versions if Japanese detected
+	if ContainsJapanese(trackName) || ContainsJapanese(artistName) {
+		// Convert to romaji (hiragana/katakana only, kanji stays)
+		romajiTrack := JapaneseToRomaji(trackName)
+		romajiArtist := JapaneseToRomaji(artistName)
+
+		// Clean and remove ALL non-ASCII characters (including kanji)
+		cleanRomajiTrack := CleanToASCII(romajiTrack)
+		cleanRomajiArtist := CleanToASCII(romajiArtist)
+
+		// Artist + Track romaji (cleaned to ASCII only)
+		if cleanRomajiArtist != "" && cleanRomajiTrack != "" {
+			romajiQuery := cleanRomajiArtist + " " + cleanRomajiTrack
+			if !containsQueryQobuz(queries, romajiQuery) {
+				queries = append(queries, romajiQuery)
+				GoLog("[Qobuz] Japanese detected, adding romaji query: %s\n", romajiQuery)
+			}
+		}
+
+		// Track romaji only (cleaned)
+		if cleanRomajiTrack != "" && cleanRomajiTrack != trackName {
+			if !containsQueryQobuz(queries, cleanRomajiTrack) {
+				queries = append(queries, cleanRomajiTrack)
+			}
+		}
+	}
+
+	// Strategy 4: Artist only as last resort
+	if artistName != "" {
+		artistOnly := CleanToASCII(JapaneseToRomaji(artistName))
+		if artistOnly != "" && !containsQueryQobuz(queries, artistOnly) {
+			queries = append(queries, artistOnly)
+		}
+	}
+
+	var allTracks []QobuzTrack
+	searchedQueries := make(map[string]bool)
+
 	for _, query := range queries {
-		searchURL := fmt.Sprintf("%s%s&limit=50&app_id=%s", string(apiBase), url.QueryEscape(query), q.appID)
+		cleanQuery := strings.TrimSpace(query)
+		if cleanQuery == "" || searchedQueries[cleanQuery] {
+			continue
+		}
+		searchedQueries[cleanQuery] = true
+
+		GoLog("[Qobuz] Searching for: %s\n", cleanQuery)
+
+		searchURL := fmt.Sprintf("%s%s&limit=50&app_id=%s", string(apiBase), url.QueryEscape(cleanQuery), q.appID)
 
 		req, err := http.NewRequest("GET", searchURL, nil)
 		if err != nil {
@@ -139,6 +536,7 @@ func (q *QobuzDownloader) SearchTrackByMetadata(trackName, artistName string) (*
 
 		resp, err := DoRequestWithUserAgent(q.client, req)
 		if err != nil {
+			GoLog("[Qobuz] Search error for '%s': %v\n", cleanQuery, err)
 			continue
 		}
 
@@ -159,19 +557,82 @@ func (q *QobuzDownloader) SearchTrackByMetadata(trackName, artistName string) (*
 		resp.Body.Close()
 
 		if len(result.Tracks.Items) > 0 {
-			// Return first result with best quality
-			for i := range result.Tracks.Items {
-				track := &result.Tracks.Items[i]
-				if track.MaximumBitDepth >= 24 {
-					return track, nil
-				}
-			}
-			// Return first result if no hi-res found
-			return &result.Tracks.Items[0], nil
+			GoLog("[Qobuz] Found %d results for '%s'\n", len(result.Tracks.Items), cleanQuery)
+			allTracks = append(allTracks, result.Tracks.Items...)
 		}
 	}
 
-	return nil, fmt.Errorf("no tracks found for: %s - %s", artistName, trackName)
+	if len(allTracks) == 0 {
+		return nil, fmt.Errorf("no tracks found for: %s - %s", artistName, trackName)
+	}
+
+	// Filter by title match first (NEW - like Tidal)
+	var titleMatches []*QobuzTrack
+	for i := range allTracks {
+		track := &allTracks[i]
+		if qobuzTitlesMatch(trackName, track.Title) {
+			titleMatches = append(titleMatches, track)
+		}
+	}
+
+	GoLog("[Qobuz] Title matches: %d out of %d results\n", len(titleMatches), len(allTracks))
+
+	// If no title matches, log warning but continue with all tracks
+	tracksToCheck := titleMatches
+	if len(titleMatches) == 0 {
+		GoLog("[Qobuz] WARNING: No title matches for '%s', checking all %d results\n", trackName, len(allTracks))
+		for i := range allTracks {
+			tracksToCheck = append(tracksToCheck, &allTracks[i])
+		}
+	}
+
+	// If duration verification is requested
+	if expectedDurationSec > 0 {
+		var durationMatches []*QobuzTrack
+		for _, track := range tracksToCheck {
+			durationDiff := track.Duration - expectedDurationSec
+			if durationDiff < 0 {
+				durationDiff = -durationDiff
+			}
+			if durationDiff <= 10 {
+				durationMatches = append(durationMatches, track)
+			}
+		}
+
+		if len(durationMatches) > 0 {
+			// Return best quality among duration matches
+			for _, track := range durationMatches {
+				if track.MaximumBitDepth >= 24 {
+					GoLog("[Qobuz] ✓ Match found: '%s' by '%s' (title+duration verified, hi-res)\n",
+						track.Title, track.Performer.Name)
+					return track, nil
+				}
+			}
+			GoLog("[Qobuz] ✓ Match found: '%s' by '%s' (title+duration verified)\n",
+				durationMatches[0].Title, durationMatches[0].Performer.Name)
+			return durationMatches[0], nil
+		}
+
+		// No duration match found
+		return nil, fmt.Errorf("no tracks found with matching title and duration (expected '%s', %ds)", trackName, expectedDurationSec)
+	}
+
+	// No duration verification, return best quality from title matches
+	for _, track := range tracksToCheck {
+		if track.MaximumBitDepth >= 24 {
+			GoLog("[Qobuz] ✓ Match found: '%s' by '%s' (title verified, hi-res)\n",
+				track.Title, track.Performer.Name)
+			return track, nil
+		}
+	}
+
+	if len(tracksToCheck) > 0 {
+		GoLog("[Qobuz] ✓ Match found: '%s' by '%s' (title verified)\n",
+			tracksToCheck[0].Title, tracksToCheck[0].Performer.Name)
+		return tracksToCheck[0], nil
+	}
+
+	return nil, fmt.Errorf("no matching track found for: %s - %s", artistName, trackName)
 }
 
 // getQobuzDownloadURLSequential requests download URL from APIs sequentially
@@ -190,7 +651,7 @@ func getQobuzDownloadURLSequential(apis []string, trackID int64, quality string)
 		// The apiURL already includes the path, just append trackID and quality
 		reqURL := fmt.Sprintf("%s%d&quality=%s", apiURL, trackID, quality)
 
-		fmt.Printf("[Qobuz] Trying: %s\n", reqURL)
+		GoLog("[Qobuz] Trying: %s\n", reqURL)
 
 		req, err := http.NewRequest("GET", reqURL, nil)
 		if err != nil {
@@ -235,7 +696,7 @@ func getQobuzDownloadURLSequential(apis []string, trackID int64, quality string)
 		}
 
 		if result.URL != "" {
-			fmt.Printf("[Qobuz] Got download URL from: %s\n", apiURL)
+			GoLog("[Qobuz] Got download URL from: %s\n", apiURL)
 			return apiURL, result.URL, nil
 		}
 
@@ -262,12 +723,7 @@ func (q *QobuzDownloader) GetDownloadURL(trackID int64, quality string) (string,
 
 // DownloadFile downloads a file from URL with User-Agent and progress tracking
 func (q *QobuzDownloader) DownloadFile(downloadURL, outputPath, itemID string) error {
-	// Set current file being downloaded (legacy)
-	SetCurrentFile(filepath.Base(outputPath))
-	SetDownloading(true)
-	defer SetDownloading(false)
-
-	// Initialize item progress if itemID provided
+	// Initialize item progress (required for all downloads)
 	if itemID != "" {
 		StartItemProgress(itemID)
 		defer CompleteItemProgress(itemID)
@@ -288,59 +744,140 @@ func (q *QobuzDownloader) DownloadFile(downloadURL, outputPath, itemID string) e
 		return fmt.Errorf("download failed: HTTP %d", resp.StatusCode)
 	}
 
+	expectedSize := resp.ContentLength
 	// Set total bytes if available
-	if resp.ContentLength > 0 {
-		SetBytesTotal(resp.ContentLength)
-		if itemID != "" {
-			SetItemBytesTotal(itemID, resp.ContentLength)
-		}
+	if expectedSize > 0 && itemID != "" {
+		SetItemBytesTotal(itemID, expectedSize)
 	}
 
 	out, err := os.Create(outputPath)
 	if err != nil {
 		return err
 	}
-	defer out.Close()
 
-	// Use appropriate progress writer
+	// Use buffered writer for better performance (256KB buffer)
+	bufWriter := bufio.NewWriterSize(out, 256*1024)
+
+	// Use item progress writer with buffered output
+	var written int64
 	if itemID != "" {
-		progressWriter := NewItemProgressWriter(out, itemID)
-		_, err = io.Copy(progressWriter, resp.Body)
+		progressWriter := NewItemProgressWriter(bufWriter, itemID)
+		written, err = io.Copy(progressWriter, resp.Body)
 	} else {
-		progressWriter := NewProgressWriter(out)
-		_, err = io.Copy(progressWriter, resp.Body)
+		// Fallback: direct copy without progress tracking
+		written, err = io.Copy(bufWriter, resp.Body)
 	}
-	return err
+
+	// Flush buffer before checking for errors
+	flushErr := bufWriter.Flush()
+	closeErr := out.Close()
+
+	// Check for any errors
+	if err != nil {
+		os.Remove(outputPath)
+		return fmt.Errorf("download interrupted: %w", err)
+	}
+	if flushErr != nil {
+		os.Remove(outputPath)
+		return fmt.Errorf("failed to flush buffer: %w", flushErr)
+	}
+	if closeErr != nil {
+		os.Remove(outputPath)
+		return fmt.Errorf("failed to close file: %w", closeErr)
+	}
+
+	// Verify file size if Content-Length was provided
+	if expectedSize > 0 && written != expectedSize {
+		os.Remove(outputPath)
+		return fmt.Errorf("incomplete download: expected %d bytes, got %d bytes", expectedSize, written)
+	}
+
+	return nil
+}
+
+// QobuzDownloadResult contains download result with quality info
+type QobuzDownloadResult struct {
+	FilePath    string
+	BitDepth    int
+	SampleRate  int
+	Title       string
+	Artist      string
+	Album       string
+	ReleaseDate string
+	TrackNumber int
+	DiscNumber  int
+	ISRC        string
 }
 
 // downloadFromQobuz downloads a track using the request parameters
-func downloadFromQobuz(req DownloadRequest) (string, error) {
+func downloadFromQobuz(req DownloadRequest) (QobuzDownloadResult, error) {
 	downloader := NewQobuzDownloader()
 
 	// Check for existing file first
 	if existingFile, exists := checkISRCExistsInternal(req.OutputDir, req.ISRC); exists {
-		return "EXISTS:" + existingFile, nil
+		return QobuzDownloadResult{FilePath: "EXISTS:" + existingFile}, nil
 	}
 
+	// Convert expected duration from ms to seconds
+	expectedDurationSec := req.DurationMS / 1000
+
 	var track *QobuzTrack
 	var err error
 
-	// Strategy 1: Search by ISRC
+	// OPTIMIZATION: Check cache first for track ID
 	if req.ISRC != "" {
-		track, err = downloader.SearchTrackByISRC(req.ISRC)
+		if cached := GetTrackIDCache().Get(req.ISRC); cached != nil && cached.QobuzTrackID > 0 {
+			GoLog("[Qobuz] Cache hit! Using cached track ID: %d\n", cached.QobuzTrackID)
+			// For Qobuz we need to search again to get full track info, but we can use the ID
+			track, err = downloader.SearchTrackByISRC(req.ISRC)
+			if err != nil {
+				GoLog("[Qobuz] Cache hit but search failed: %v\n", err)
+				track = nil
+			}
+		}
 	}
 
-	// Strategy 2: Search by metadata
+	// Strategy 1: Search by ISRC with duration verification
+	if track == nil && req.ISRC != "" {
+		GoLog("[Qobuz] Trying ISRC search: %s\n", req.ISRC)
+		track, err = downloader.SearchTrackByISRCWithDuration(req.ISRC, expectedDurationSec)
+		// Verify artist AND title
+		if track != nil {
+			if !qobuzArtistsMatch(req.ArtistName, track.Performer.Name) {
+				GoLog("[Qobuz] Artist mismatch from ISRC search: expected '%s', got '%s'. Rejecting.\n",
+					req.ArtistName, track.Performer.Name)
+				track = nil
+			} else if !qobuzTitlesMatch(req.TrackName, track.Title) {
+				GoLog("[Qobuz] Title mismatch from ISRC search: expected '%s', got '%s'. Rejecting.\n",
+					req.TrackName, track.Title)
+				track = nil
+			}
+		}
+	}
+
+	// Strategy 2: Search by metadata with duration verification (includes title verification)
 	if track == nil {
-		track, err = downloader.SearchTrackByMetadata(req.TrackName, req.ArtistName)
+		track, err = downloader.SearchTrackByMetadataWithDuration(req.TrackName, req.ArtistName, expectedDurationSec)
+		// Verify artist (title already verified in SearchTrackByMetadataWithDuration)
+		if track != nil && !qobuzArtistsMatch(req.ArtistName, track.Performer.Name) {
+			GoLog("[Qobuz] Artist mismatch from metadata search: expected '%s', got '%s'. Rejecting.\n",
+				req.ArtistName, track.Performer.Name)
+			track = nil
+		}
 	}
 
 	if track == nil {
-		errMsg := "could not find track on Qobuz"
+		errMsg := "could not find matching track on Qobuz (artist/duration mismatch)"
 		if err != nil {
 			errMsg = err.Error()
 		}
-		return "", fmt.Errorf("qobuz search failed: %s", errMsg)
+		return QobuzDownloadResult{}, fmt.Errorf("qobuz search failed: %s", errMsg)
+	}
+
+	// Log match found and cache the track ID
+	GoLog("[Qobuz] Match found: '%s' by '%s' (duration: %ds)\n", track.Title, track.Performer.Name, track.Duration)
+	if req.ISRC != "" {
+		GetTrackIDCache().SetQobuz(req.ISRC, track.ID)
 	}
 
 	// Build filename
@@ -357,7 +894,7 @@ func downloadFromQobuz(req DownloadRequest) (string, error) {
 
 	// Check if file already exists
 	if fileInfo, statErr := os.Stat(outputPath); statErr == nil && fileInfo.Size() > 0 {
-		return "EXISTS:" + outputPath, nil
+		return QobuzDownloadResult{FilePath: "EXISTS:" + outputPath}, nil
 	}
 
 	// Map quality from Tidal format to Qobuz format
@@ -372,79 +909,105 @@ func downloadFromQobuz(req DownloadRequest) (string, error) {
 	case "HI_RES_LOSSLESS":
 		qobuzQuality = "27" // 24-bit 192kHz
 	}
-	fmt.Printf("[Qobuz] Using quality: %s (mapped from %s)\n", qobuzQuality, req.Quality)
+	GoLog("[Qobuz] Using quality: %s (mapped from %s)\n", qobuzQuality, req.Quality)
+
+	// Get actual quality from track metadata
+	actualBitDepth := track.MaximumBitDepth
+	actualSampleRate := int(track.MaximumSamplingRate * 1000) // Convert kHz to Hz
+	GoLog("[Qobuz] Actual quality: %d-bit/%.1fkHz\n", actualBitDepth, track.MaximumSamplingRate)
 
 	// Get download URL using parallel API requests
 	downloadURL, err := downloader.GetDownloadURL(track.ID, qobuzQuality)
 	if err != nil {
-		return "", fmt.Errorf("failed to get download URL: %w", err)
+		return QobuzDownloadResult{}, fmt.Errorf("failed to get download URL: %w", err)
 	}
 
-	// Download file with item ID for progress tracking
+	// START PARALLEL: Fetch cover and lyrics while downloading audio
+	var parallelResult *ParallelDownloadResult
+	parallelDone := make(chan struct{})
+	go func() {
+		defer close(parallelDone)
+		parallelResult = FetchCoverAndLyricsParallel(
+			req.CoverURL,
+			req.EmbedMaxQualityCover,
+			req.SpotifyID,
+			req.TrackName,
+			req.ArtistName,
+			req.EmbedLyrics,
+		)
+	}()
+
+	// Download audio file with item ID for progress tracking
 	if err := downloader.DownloadFile(downloadURL, outputPath, req.ItemID); err != nil {
-		return "", fmt.Errorf("download failed: %w", err)
+		return QobuzDownloadResult{}, fmt.Errorf("download failed: %w", err)
+	}
+
+	// Wait for parallel operations to complete
+	<-parallelDone
+
+	// Set progress to 100% and status to finalizing (before embedding)
+	// This makes the UI show "Finalizing..." while embedding happens
+	if req.ItemID != "" {
+		SetItemProgress(req.ItemID, 1.0, 0, 0)
+		SetItemFinalizing(req.ItemID)
+	}
+
+	// Embed metadata using parallel-fetched cover data
+	// Use metadata from the actual Qobuz track found (more accurate than request) but prefer
+	// requested Album Name to avoid ISRC version mismatches (e.g. Compilations vs Original)
+	albumName := track.Album.Title
+	if req.AlbumName != "" {
+		albumName = req.AlbumName
 	}
 
-	// Embed metadata
 	metadata := Metadata{
-		Title:       req.TrackName,
-		Artist:      req.ArtistName,
-		Album:       req.AlbumName,
-		AlbumArtist: req.AlbumArtist,
-		Date:        req.ReleaseDate,
-		TrackNumber: req.TrackNumber,
+		Title:       track.Title,
+		Artist:      track.Performer.Name,
+		Album:       albumName,
+		AlbumArtist: req.AlbumArtist, // Qobuz track struct might not have this handy, keep req or check album struct
+		Date:        track.Album.ReleaseDate,
+		TrackNumber: track.TrackNumber,
 		TotalTracks: req.TotalTracks,
-		DiscNumber:  req.DiscNumber,
-		ISRC:        req.ISRC,
+		DiscNumber:  req.DiscNumber, // QobuzTrack struct usually doesn't have disc info in simple search result
+		ISRC:        track.ISRC,
 	}
 
-	// Download cover to memory (avoids file permission issues on Android)
+	// Use cover data from parallel fetch
 	var coverData []byte
-	if req.CoverURL != "" {
-		fmt.Println("[Qobuz] Downloading cover to memory...")
-		data, err := downloadCoverToMemory(req.CoverURL, req.EmbedMaxQualityCover)
-		if err == nil {
-			coverData = data
-			fmt.Printf("[Qobuz] Cover downloaded successfully (%d bytes)\n", len(coverData))
-		} else {
-			fmt.Printf("[Qobuz] Warning: failed to download cover: %v\n", err)
-		}
+	if parallelResult != nil && parallelResult.CoverData != nil {
+		coverData = parallelResult.CoverData
+		GoLog("[Qobuz] Using parallel-fetched cover (%d bytes)\n", len(coverData))
 	}
 
 	if err := EmbedMetadataWithCoverData(outputPath, metadata, coverData); err != nil {
 		fmt.Printf("Warning: failed to embed metadata: %v\n", err)
 	}
 
-	// Embed lyrics if enabled
-	if req.EmbedLyrics {
-		fmt.Println("[Qobuz] Fetching lyrics...")
-		lyricsClient := NewLyricsClient()
-		lyrics, lyricsErr := lyricsClient.FetchLyricsAllSources(req.SpotifyID, req.TrackName, req.ArtistName)
-		if lyricsErr != nil {
-			fmt.Printf("[Qobuz] Warning: lyrics fetch error: %v\n", lyricsErr)
-		} else if lyrics == nil || len(lyrics.Lines) == 0 {
-			fmt.Println("[Qobuz] No lyrics found for this track")
+	// Embed lyrics from parallel fetch
+	if req.EmbedLyrics && parallelResult != nil && parallelResult.LyricsLRC != "" {
+		GoLog("[Qobuz] Embedding parallel-fetched lyrics (%d lines)...\n", len(parallelResult.LyricsData.Lines))
+		if embedErr := EmbedLyrics(outputPath, parallelResult.LyricsLRC); embedErr != nil {
+			GoLog("[Qobuz] Warning: failed to embed lyrics: %v\n", embedErr)
 		} else {
-			fmt.Printf("[Qobuz] Lyrics found (%d lines), embedding...\n", len(lyrics.Lines))
-			
-			// Convert Japanese lyrics to romaji if enabled
-			if req.ConvertLyricsToRomaji {
-				for i := range lyrics.Lines {
-					if ContainsKana(lyrics.Lines[i].Words) {
-						lyrics.Lines[i].Words = ToRomaji(lyrics.Lines[i].Words)
-					}
-				}
-				fmt.Println("[Qobuz] Converted Japanese lyrics to romaji")
-			}
-			
-			lrcContent := convertToLRC(lyrics)
-			if embedErr := EmbedLyrics(outputPath, lrcContent); embedErr != nil {
-				fmt.Printf("[Qobuz] Warning: failed to embed lyrics: %v\n", embedErr)
-			} else {
-				fmt.Println("[Qobuz] Lyrics embedded successfully")
-			}
+			fmt.Println("[Qobuz] Lyrics embedded successfully")
 		}
+	} else if req.EmbedLyrics {
+		fmt.Println("[Qobuz] No lyrics available from parallel fetch")
 	}
 
-	return outputPath, nil
+	// Add to ISRC index for fast duplicate checking
+	AddToISRCIndex(req.OutputDir, req.ISRC, outputPath)
+
+	return QobuzDownloadResult{
+		FilePath:    outputPath,
+		BitDepth:    actualBitDepth,
+		SampleRate:  actualSampleRate,
+		Title:       track.Title,
+		Artist:      track.Performer.Name,
+		Album:       track.Album.Title,
+		ReleaseDate: track.Album.ReleaseDate,
+		TrackNumber: track.TrackNumber,
+		DiscNumber:  req.DiscNumber, // Qobuz track struct limitations
+		ISRC:        track.ISRC,
+	}, nil
 }

go_backend/romaji.go

@@ -5,109 +5,61 @@ import (
 	"unicode"
 )
 
-// Japanese character ranges
-const (
-	hiraganaStart = 0x3040
-	hiraganaEnd   = 0x309F
-	katakanaStart = 0x30A0
-	katakanaEnd   = 0x30FF
-	kanjiStart    = 0x4E00
-	kanjiEnd      = 0x9FFF
-)
-
-// hiraganaToRomaji maps hiragana characters to romaji
+// Hiragana to Romaji mapping
 var hiraganaToRomaji = map[rune]string{
-	// Basic vowels
 	'あ': "a", 'い': "i", 'う': "u", 'え': "e", 'お': "o",
-	// K-row
 	'か': "ka", 'き': "ki", 'く': "ku", 'け': "ke", 'こ': "ko",
-	// S-row
 	'さ': "sa", 'し': "shi", 'す': "su", 'せ': "se", 'そ': "so",
-	// T-row
 	'た': "ta", 'ち': "chi", 'つ': "tsu", 'て': "te", 'と': "to",
-	// N-row
 	'な': "na", 'に': "ni", 'ぬ': "nu", 'ね': "ne", 'の': "no",
-	// H-row
 	'は': "ha", 'ひ': "hi", 'ふ': "fu", 'へ': "he", 'ほ': "ho",
-	// M-row
 	'ま': "ma", 'み': "mi", 'む': "mu", 'め': "me", 'も': "mo",
-	// Y-row
 	'や': "ya", 'ゆ': "yu", 'よ': "yo",
-	// R-row
 	'ら': "ra", 'り': "ri", 'る': "ru", 'れ': "re", 'ろ': "ro",
-	// W-row
-	'わ': "wa", 'を': "wo",
-	// N
-	'ん': "n",
-	// Voiced (dakuten) - G-row
+	'わ': "wa", 'を': "wo", 'ん': "n",
+	// Dakuten (voiced)
 	'が': "ga", 'ぎ': "gi", 'ぐ': "gu", 'げ': "ge", 'ご': "go",
-	// Z-row
 	'ざ': "za", 'じ': "ji", 'ず': "zu", 'ぜ': "ze", 'ぞ': "zo",
-	// D-row
 	'だ': "da", 'ぢ': "ji", 'づ': "zu", 'で': "de", 'ど': "do",
-	// B-row
 	'ば': "ba", 'び': "bi", 'ぶ': "bu", 'べ': "be", 'ぼ': "bo",
-	// P-row (handakuten)
+	// Handakuten (semi-voiced)
 	'ぱ': "pa", 'ぴ': "pi", 'ぷ': "pu", 'ぺ': "pe", 'ぽ': "po",
 	// Small characters
 	'ゃ': "ya", 'ゅ': "yu", 'ょ': "yo",
+	'っ': "", // Double consonant marker
 	'ぁ': "a", 'ぃ': "i", 'ぅ': "u", 'ぇ': "e", 'ぉ': "o",
-	'っ': "", // Small tsu - handled specially
-	// Long vowel mark
-	'ー': "",
 }
 
-// katakanaToRomaji maps katakana characters to romaji
+// Katakana to Romaji mapping
 var katakanaToRomaji = map[rune]string{
-	// Basic vowels
 	'ア': "a", 'イ': "i", 'ウ': "u", 'エ': "e", 'オ': "o",
-	// K-row
 	'カ': "ka", 'キ': "ki", 'ク': "ku", 'ケ': "ke", 'コ': "ko",
-	// S-row
 	'サ': "sa", 'シ': "shi", 'ス': "su", 'セ': "se", 'ソ': "so",
-	// T-row
 	'タ': "ta", 'チ': "chi", 'ツ': "tsu", 'テ': "te", 'ト': "to",
-	// N-row
 	'ナ': "na", 'ニ': "ni", 'ヌ': "nu", 'ネ': "ne", 'ノ': "no",
-	// H-row
 	'ハ': "ha", 'ヒ': "hi", 'フ': "fu", 'ヘ': "he", 'ホ': "ho",
-	// M-row
 	'マ': "ma", 'ミ': "mi", 'ム': "mu", 'メ': "me", 'モ': "mo",
-	// Y-row
 	'ヤ': "ya", 'ユ': "yu", 'ヨ': "yo",
-	// R-row
 	'ラ': "ra", 'リ': "ri", 'ル': "ru", 'レ': "re", 'ロ': "ro",
-	// W-row
-	'ワ': "wa", 'ヲ': "wo",
-	// N
-	'ン': "n",
-	// Voiced (dakuten) - G-row
+	'ワ': "wa", 'ヲ': "wo", 'ン': "n",
+	// Dakuten (voiced)
 	'ガ': "ga", 'ギ': "gi", 'グ': "gu", 'ゲ': "ge", 'ゴ': "go",
-	// Z-row
 	'ザ': "za", 'ジ': "ji", 'ズ': "zu", 'ゼ': "ze", 'ゾ': "zo",
-	// D-row
 	'ダ': "da", 'ヂ': "ji", 'ヅ': "zu", 'デ': "de", 'ド': "do",
-	// B-row
 	'バ': "ba", 'ビ': "bi", 'ブ': "bu", 'ベ': "be", 'ボ': "bo",
-	// P-row (handakuten)
+	// Handakuten (semi-voiced)
 	'パ': "pa", 'ピ': "pi", 'プ': "pu", 'ペ': "pe", 'ポ': "po",
 	// Small characters
 	'ャ': "ya", 'ュ': "yu", 'ョ': "yo",
+	'ッ': "", // Double consonant marker
 	'ァ': "a", 'ィ': "i", 'ゥ': "u", 'ェ': "e", 'ォ': "o",
-	'ッ': "", // Small tsu - handled specially
 	// Extended katakana
+	'ー': "", // Long vowel mark
 	'ヴ': "vu",
-	// Long vowel mark
-	'ー': "",
 }
 
-// Extended katakana combinations (multi-character)
-var katakanaExtended = map[string]string{
-	"ファ": "fa", "フィ": "fi", "フェ": "fe", "フォ": "fo",
-}
-
-// Combination mappings for small ya/yu/yo
-var hiraganaCombo = map[string]string{
+// Combination mappings for きゃ, しゃ, etc.
+var combinationHiragana = map[string]string{
 	"きゃ": "kya", "きゅ": "kyu", "きょ": "kyo",
 	"しゃ": "sha", "しゅ": "shu", "しょ": "sho",
 	"ちゃ": "cha", "ちゅ": "chu", "ちょ": "cho",
@@ -121,7 +73,7 @@ var hiraganaCombo = map[string]string{
 	"ぴゃ": "pya", "ぴゅ": "pyu", "ぴょ": "pyo",
 }
 
-var katakanaCombo = map[string]string{
+var combinationKatakana = map[string]string{
 	"キャ": "kya", "キュ": "kyu", "キョ": "kyo",
 	"シャ": "sha", "シュ": "shu", "ショ": "sho",
 	"チャ": "cha", "チュ": "chu", "チョ": "cho",
@@ -133,15 +85,13 @@ var katakanaCombo = map[string]string{
 	"ジャ": "ja", "ジュ": "ju", "ジョ": "jo",
 	"ビャ": "bya", "ビュ": "byu", "ビョ": "byo",
 	"ピャ": "pya", "ピュ": "pyu", "ピョ": "pyo",
-	// Extended katakana combinations
-	"ティ": "ti", "ディ": "di",
-	"トゥ": "tu", "ドゥ": "du",
+	// Extended combinations
+	"ティ": "ti", "ディ": "di", "トゥ": "tu", "ドゥ": "du",
 	"ファ": "fa", "フィ": "fi", "フェ": "fe", "フォ": "fo",
 	"ウィ": "wi", "ウェ": "we", "ウォ": "wo",
-	"ヴァ": "va", "ヴィ": "vi", "ヴェ": "ve", "ヴォ": "vo",
 }
 
-// ContainsJapanese checks if a string contains Japanese characters (Hiragana, Katakana, or Kanji)
+// ContainsJapanese checks if a string contains Japanese characters
 func ContainsJapanese(s string) bool {
 	for _, r := range s {
 		if isHiragana(r) || isKatakana(r) || isKanji(r) {
@@ -151,107 +101,72 @@ func ContainsJapanese(s string) bool {
 	return false
 }
 
-// ContainsKana checks if a string contains Hiragana or Katakana (convertible to romaji)
-func ContainsKana(s string) bool {
-	for _, r := range s {
-		if isHiragana(r) || isKatakana(r) {
-			return true
-		}
-	}
-	return false
-}
-
 func isHiragana(r rune) bool {
-	return r >= hiraganaStart && r <= hiraganaEnd
+	return r >= 0x3040 && r <= 0x309F
 }
 
 func isKatakana(r rune) bool {
-	return r >= katakanaStart && r <= katakanaEnd
+	return r >= 0x30A0 && r <= 0x30FF
 }
 
 func isKanji(r rune) bool {
-	return r >= kanjiStart && r <= kanjiEnd
+	return (r >= 0x4E00 && r <= 0x9FFF) || // CJK Unified Ideographs
+		(r >= 0x3400 && r <= 0x4DBF) // CJK Unified Ideographs Extension A
 }
 
-// ToRomaji converts Japanese kana (Hiragana/Katakana) to romaji
-// Kanji characters are preserved as-is since they require dictionary lookup
-func ToRomaji(s string) string {
-	if !ContainsKana(s) {
-		return s
+// JapaneseToRomaji converts Japanese text (hiragana/katakana) to romaji
+// Note: Kanji cannot be converted without a dictionary, so they are kept as-is
+func JapaneseToRomaji(text string) string {
+	if !ContainsJapanese(text) {
+		return text
 	}
 
-	runes := []rune(s)
 	var result strings.Builder
-	result.Grow(len(s) * 2) // Romaji is typically longer
-
+	runes := []rune(text)
 	i := 0
+
 	for i < len(runes) {
-		r := runes[i]
+		// Check for っ/ッ (double consonant)
+		if i < len(runes)-1 && (runes[i] == 'っ' || runes[i] == 'ッ') {
+			nextRomaji := ""
+			if romaji, ok := hiraganaToRomaji[runes[i+1]]; ok {
+				nextRomaji = romaji
+			} else if romaji, ok := katakanaToRomaji[runes[i+1]]; ok {
+				nextRomaji = romaji
+			}
+			if len(nextRomaji) > 0 {
+				result.WriteByte(nextRomaji[0]) // Double the first consonant
+			}
+			i++
+			continue
+		}
 
-		// Check for two-character combinations first
-		if i+1 < len(runes) {
+		// Check for two-character combinations
+		if i < len(runes)-1 {
 			combo := string(runes[i : i+2])
-			if romaji, ok := hiraganaCombo[combo]; ok {
+			if romaji, ok := combinationHiragana[combo]; ok {
 				result.WriteString(romaji)
 				i += 2
 				continue
 			}
-			if romaji, ok := katakanaCombo[combo]; ok {
+			if romaji, ok := combinationKatakana[combo]; ok {
 				result.WriteString(romaji)
 				i += 2
 				continue
 			}
 		}
 
-		// Handle small tsu (っ/ッ) - doubles the next consonant
-		if r == 'っ' || r == 'ッ' {
-			if i+1 < len(runes) {
-				nextRune := runes[i+1]
-				var nextRomaji string
-				if romaji, ok := hiraganaToRomaji[nextRune]; ok {
-					nextRomaji = romaji
-				} else if romaji, ok := katakanaToRomaji[nextRune]; ok {
-					nextRomaji = romaji
-				}
-				if len(nextRomaji) > 0 {
-					result.WriteByte(nextRomaji[0]) // Double the consonant
-				}
-			}
-			i++
-			continue
-		}
-
-		// Handle long vowel mark (ー)
-		if r == 'ー' {
-			// Extend the previous vowel
-			resultStr := result.String()
-			if len(resultStr) > 0 {
-				lastChar := resultStr[len(resultStr)-1]
-				if lastChar == 'a' || lastChar == 'i' || lastChar == 'u' || lastChar == 'e' || lastChar == 'o' {
-					result.WriteByte(lastChar)
-				}
-			}
-			i++
-			continue
-		}
-
 		// Single character conversion
+		r := runes[i]
 		if romaji, ok := hiraganaToRomaji[r]; ok {
 			result.WriteString(romaji)
-			i++
-			continue
-		}
-
-		if romaji, ok := katakanaToRomaji[r]; ok {
+		} else if romaji, ok := katakanaToRomaji[r]; ok {
 			result.WriteString(romaji)
-			i++
-			continue
-		}
-
-		// Keep non-Japanese characters as-is
-		if unicode.IsSpace(r) {
-			result.WriteRune(' ')
+		} else if isKanji(r) {
+			// Keep kanji as-is (would need dictionary for proper conversion)
+			result.WriteRune(r)
 		} else {
+			// Keep other characters (punctuation, spaces, etc.)
 			result.WriteRune(r)
 		}
 		i++
@@ -260,17 +175,48 @@ func ToRomaji(s string) string {
 	return result.String()
 }
 
-// GetRomajiVariants returns search variants for Japanese text
-// Returns the original string plus romaji version if applicable
-func GetRomajiVariants(s string) []string {
-	variants := []string{s}
+// BuildSearchQuery creates a search query from track name and artist
+// Converts Japanese to romaji if present
+func BuildSearchQuery(trackName, artistName string) string {
+	// Convert Japanese to romaji
+	trackRomaji := JapaneseToRomaji(trackName)
+	artistRomaji := JapaneseToRomaji(artistName)
 
-	if ContainsKana(s) {
-		romaji := ToRomaji(s)
-		if romaji != s && strings.TrimSpace(romaji) != "" {
-			variants = append(variants, romaji)
+	// Clean up the query - remove special characters that might interfere with search
+	trackClean := cleanSearchQuery(trackRomaji)
+	artistClean := cleanSearchQuery(artistRomaji)
+
+	return strings.TrimSpace(artistClean + " " + trackClean)
+}
+
+// cleanSearchQuery removes special characters that might interfere with search
+func cleanSearchQuery(s string) string {
+	var result strings.Builder
+	for _, r := range s {
+		if unicode.IsLetter(r) || unicode.IsNumber(r) || unicode.IsSpace(r) {
+			result.WriteRune(r)
+		} else if r == '-' || r == '\'' {
+			result.WriteRune(r)
 		}
 	}
-
-	return variants
+	return strings.TrimSpace(result.String())
+}
+
+// CleanToASCII removes all non-ASCII characters and keeps only letters, numbers, spaces
+// This is useful for creating search queries that work better with Tidal's search
+func CleanToASCII(s string) string {
+	var result strings.Builder
+	for _, r := range s {
+		// Keep only ASCII letters, numbers, spaces, and basic punctuation
+		if (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') ||
+			(r >= '0' && r <= '9') || r == ' ' || r == '-' || r == '\'' {
+			result.WriteRune(r)
+		} else if r == ',' || r == '.' {
+			// Convert punctuation to space
+			result.WriteRune(' ')
+		}
+	}
+	// Clean up multiple spaces
+	cleaned := strings.Join(strings.Fields(result.String()), " ")
+	return strings.TrimSpace(cleaned)
 }

go_backend/songlink.go

@@ -6,6 +6,8 @@ import (
 	"fmt"
 	"net/http"
 	"net/url"
+	"strings"
+	"sync"
 	"time"
 )
 
@@ -20,20 +22,37 @@ type TrackAvailability struct {
 	Tidal     bool   `json:"tidal"`
 	Amazon    bool   `json:"amazon"`
 	Qobuz     bool   `json:"qobuz"`
+	Deezer    bool   `json:"deezer"`
 	TidalURL  string `json:"tidal_url,omitempty"`
 	AmazonURL string `json:"amazon_url,omitempty"`
 	QobuzURL  string `json:"qobuz_url,omitempty"`
+	DeezerURL string `json:"deezer_url,omitempty"`
+	DeezerID  string `json:"deezer_id,omitempty"`
 }
 
-// NewSongLinkClient creates a new SongLink client
+var (
+	// Global SongLink client instance for connection reuse
+	globalSongLinkClient *SongLinkClient
+	songLinkClientOnce   sync.Once
+)
+
+// NewSongLinkClient creates a new SongLink client (returns singleton for connection reuse)
 func NewSongLinkClient() *SongLinkClient {
-	return &SongLinkClient{
-		client: NewHTTPClientWithTimeout(SongLinkTimeout), // 30s timeout
-	}
+	songLinkClientOnce.Do(func() {
+		globalSongLinkClient = &SongLinkClient{
+			client: NewHTTPClientWithTimeout(SongLinkTimeout), // 30s timeout
+		}
+	})
+	return globalSongLinkClient
 }
 
 // CheckTrackAvailability checks track availability on streaming platforms
 func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc string) (*TrackAvailability, error) {
+	// Validate Spotify ID format (should be 22 characters alphanumeric)
+	if spotifyTrackID == "" {
+		return nil, fmt.Errorf("spotify track ID is empty")
+	}
+	
 	// Use global rate limiter - blocks until request is allowed
 	songLinkRateLimiter.WaitForSlot()
 
@@ -57,8 +76,18 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 	}
 	defer resp.Body.Close()
 
+	// Handle specific error codes
+	if resp.StatusCode == 400 {
+		return nil, fmt.Errorf("track not found on SongLink (invalid Spotify ID or track unavailable)")
+	}
+	if resp.StatusCode == 404 {
+		return nil, fmt.Errorf("track not found on any streaming platform")
+	}
+	if resp.StatusCode == 429 {
+		return nil, fmt.Errorf("SongLink rate limit exceeded")
+	}
 	if resp.StatusCode != 200 {
-		return nil, fmt.Errorf("API returned status %d", resp.StatusCode)
+		return nil, fmt.Errorf("SongLink API returned status %d", resp.StatusCode)
 	}
 
 	body, err := ReadResponseBody(resp)
@@ -92,7 +121,15 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 		availability.AmazonURL = amazonLink.URL
 	}
 
-	// Check Qobuz using ISRC
+	// Check Deezer
+	if deezerLink, ok := songLinkResp.LinksByPlatform["deezer"]; ok && deezerLink.URL != "" {
+		availability.Deezer = true
+		availability.DeezerURL = deezerLink.URL
+		// Extract Deezer ID from URL (e.g., https://www.deezer.com/track/123456)
+		availability.DeezerID = extractDeezerIDFromURL(deezerLink.URL)
+	}
+
+	// Check Qobuz using ISRC (SongLink doesn't support Qobuz directly)
 	if isrc != "" {
 		availability.Qobuz = checkQobuzAvailability(isrc)
 	}
@@ -151,3 +188,357 @@ func checkQobuzAvailability(isrc string) bool {
 
 	return searchResp.Tracks.Total > 0
 }
+
+// extractDeezerIDFromURL extracts Deezer track/album/artist ID from URL
+func extractDeezerIDFromURL(deezerURL string) string {
+	// URL format: https://www.deezer.com/track/123456 or https://www.deezer.com/en/track/123456
+	parts := strings.Split(deezerURL, "/")
+	if len(parts) > 0 {
+		// Get the last part which should be the ID
+		lastPart := parts[len(parts)-1]
+		// Remove any query parameters
+		if idx := strings.Index(lastPart, "?"); idx > 0 {
+			lastPart = lastPart[:idx]
+		}
+		return lastPart
+	}
+	return ""
+}
+
+// GetDeezerIDFromSpotify converts a Spotify track ID to Deezer track ID using SongLink
+func (s *SongLinkClient) GetDeezerIDFromSpotify(spotifyTrackID string) (string, error) {
+	availability, err := s.CheckTrackAvailability(spotifyTrackID, "")
+	if err != nil {
+		return "", err
+	}
+	
+	if !availability.Deezer || availability.DeezerID == "" {
+		return "", fmt.Errorf("track not found on Deezer")
+	}
+	
+	return availability.DeezerID, nil
+}
+
+// AlbumAvailability represents album availability on different platforms
+type AlbumAvailability struct {
+	SpotifyID string `json:"spotify_id"`
+	Deezer    bool   `json:"deezer"`
+	DeezerURL string `json:"deezer_url,omitempty"`
+	DeezerID  string `json:"deezer_id,omitempty"`
+}
+
+// CheckAlbumAvailability checks album availability on streaming platforms using SongLink
+func (s *SongLinkClient) CheckAlbumAvailability(spotifyAlbumID string) (*AlbumAvailability, error) {
+	// Use global rate limiter
+	songLinkRateLimiter.WaitForSlot()
+
+	// Build API URL for album
+	spotifyBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9vcGVuLnNwb3RpZnkuY29tL2FsYnVtLw==")
+	spotifyURL := fmt.Sprintf("%s%s", string(spotifyBase), spotifyAlbumID)
+
+	apiBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9hcGkuc29uZy5saW5rL3YxLWFscGhhLjEvbGlua3M/dXJsPQ==")
+	apiURL := fmt.Sprintf("%s%s", string(apiBase), url.QueryEscape(spotifyURL))
+
+	req, err := http.NewRequest("GET", apiURL, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	retryConfig := DefaultRetryConfig()
+	resp, err := DoRequestWithRetry(s.client, req, retryConfig)
+	if err != nil {
+		return nil, fmt.Errorf("failed to check album availability: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("API returned status %d", resp.StatusCode)
+	}
+
+	body, err := ReadResponseBody(resp)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response: %w", err)
+	}
+
+	var songLinkResp struct {
+		LinksByPlatform map[string]struct {
+			URL string `json:"url"`
+		} `json:"linksByPlatform"`
+	}
+
+	if err := json.Unmarshal(body, &songLinkResp); err != nil {
+		return nil, fmt.Errorf("failed to decode response: %w", err)
+	}
+
+	availability := &AlbumAvailability{
+		SpotifyID: spotifyAlbumID,
+	}
+
+	// Check Deezer
+	if deezerLink, ok := songLinkResp.LinksByPlatform["deezer"]; ok && deezerLink.URL != "" {
+		availability.Deezer = true
+		availability.DeezerURL = deezerLink.URL
+		availability.DeezerID = extractDeezerIDFromURL(deezerLink.URL)
+	}
+
+	return availability, nil
+}
+
+// GetDeezerAlbumIDFromSpotify converts a Spotify album ID to Deezer album ID using SongLink
+func (s *SongLinkClient) GetDeezerAlbumIDFromSpotify(spotifyAlbumID string) (string, error) {
+	availability, err := s.CheckAlbumAvailability(spotifyAlbumID)
+	if err != nil {
+		return "", err
+	}
+	
+	if !availability.Deezer || availability.DeezerID == "" {
+		return "", fmt.Errorf("album not found on Deezer")
+	}
+	
+	return availability.DeezerID, nil
+}
+
+// ========================================
+// Deezer ID Support - Query SongLink using Deezer as source
+// ========================================
+
+// CheckAvailabilityFromDeezer checks track availability using Deezer track ID as source
+// This is useful when we have Deezer metadata and want to find the track on other platforms
+func (s *SongLinkClient) CheckAvailabilityFromDeezer(deezerTrackID string) (*TrackAvailability, error) {
+	if deezerTrackID == "" {
+		return nil, fmt.Errorf("deezer track ID is empty")
+	}
+	
+	// Use global rate limiter
+	songLinkRateLimiter.WaitForSlot()
+
+	// Build Deezer URL
+	deezerURL := fmt.Sprintf("https://www.deezer.com/track/%s", deezerTrackID)
+
+	// Build API URL using Deezer URL as source
+	apiBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9hcGkuc29uZy5saW5rL3YxLWFscGhhLjEvbGlua3M/dXJsPQ==")
+	apiURL := fmt.Sprintf("%s%s&userCountry=US", string(apiBase), url.QueryEscape(deezerURL))
+
+	req, err := http.NewRequest("GET", apiURL, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	retryConfig := DefaultRetryConfig()
+	resp, err := DoRequestWithRetry(s.client, req, retryConfig)
+	if err != nil {
+		return nil, fmt.Errorf("failed to check availability: %w", err)
+	}
+	defer resp.Body.Close()
+
+	// Handle specific error codes
+	if resp.StatusCode == 400 {
+		return nil, fmt.Errorf("track not found on SongLink (invalid Deezer ID)")
+	}
+	if resp.StatusCode == 404 {
+		return nil, fmt.Errorf("track not found on any streaming platform")
+	}
+	if resp.StatusCode == 429 {
+		return nil, fmt.Errorf("SongLink rate limit exceeded")
+	}
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("SongLink API returned status %d", resp.StatusCode)
+	}
+
+	body, err := ReadResponseBody(resp)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response: %w", err)
+	}
+
+	var songLinkResp struct {
+		LinksByPlatform map[string]struct {
+			URL string `json:"url"`
+		} `json:"linksByPlatform"`
+		EntitiesByUniqueId map[string]struct {
+			ID         string `json:"id"`
+			Type       string `json:"type"`
+			Title      string `json:"title"`
+			ArtistName string `json:"artistName"`
+		} `json:"entitiesByUniqueId"`
+	}
+
+	if err := json.Unmarshal(body, &songLinkResp); err != nil {
+		return nil, fmt.Errorf("failed to decode response: %w", err)
+	}
+
+	availability := &TrackAvailability{
+		Deezer:   true,
+		DeezerID: deezerTrackID,
+	}
+
+	// Check Spotify
+	if spotifyLink, ok := songLinkResp.LinksByPlatform["spotify"]; ok && spotifyLink.URL != "" {
+		// Extract Spotify ID from URL
+		availability.SpotifyID = extractSpotifyIDFromURL(spotifyLink.URL)
+	}
+
+	// Check Tidal
+	if tidalLink, ok := songLinkResp.LinksByPlatform["tidal"]; ok && tidalLink.URL != "" {
+		availability.Tidal = true
+		availability.TidalURL = tidalLink.URL
+	}
+
+	// Check Amazon
+	if amazonLink, ok := songLinkResp.LinksByPlatform["amazonMusic"]; ok && amazonLink.URL != "" {
+		availability.Amazon = true
+		availability.AmazonURL = amazonLink.URL
+	}
+
+	// Check Deezer URL
+	if deezerLink, ok := songLinkResp.LinksByPlatform["deezer"]; ok && deezerLink.URL != "" {
+		availability.DeezerURL = deezerLink.URL
+	}
+
+	return availability, nil
+}
+
+// CheckAvailabilityByPlatform checks track availability using any supported platform
+// platform: "spotify", "deezer", "tidal", "amazonMusic", "appleMusic", "youtube", etc.
+// entityType: "song" or "album"
+// entityID: the ID on that platform
+func (s *SongLinkClient) CheckAvailabilityByPlatform(platform, entityType, entityID string) (*TrackAvailability, error) {
+	if entityID == "" {
+		return nil, fmt.Errorf("%s ID is empty", platform)
+	}
+	
+	// Use global rate limiter
+	songLinkRateLimiter.WaitForSlot()
+
+	// Build API URL using platform, type, and id parameters (as per API docs)
+	// https://api.song.link/v1-alpha.1/links?platform=deezer&type=song&id=123456
+	apiURL := fmt.Sprintf("https://api.song.link/v1-alpha.1/links?platform=%s&type=%s&id=%s&userCountry=US",
+		url.QueryEscape(platform),
+		url.QueryEscape(entityType),
+		url.QueryEscape(entityID))
+
+	req, err := http.NewRequest("GET", apiURL, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	retryConfig := DefaultRetryConfig()
+	resp, err := DoRequestWithRetry(s.client, req, retryConfig)
+	if err != nil {
+		return nil, fmt.Errorf("failed to check availability: %w", err)
+	}
+	defer resp.Body.Close()
+
+	// Handle specific error codes
+	if resp.StatusCode == 400 {
+		return nil, fmt.Errorf("track not found on SongLink (invalid %s ID)", platform)
+	}
+	if resp.StatusCode == 404 {
+		return nil, fmt.Errorf("track not found on any streaming platform")
+	}
+	if resp.StatusCode == 429 {
+		return nil, fmt.Errorf("SongLink rate limit exceeded")
+	}
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("SongLink API returned status %d", resp.StatusCode)
+	}
+
+	body, err := ReadResponseBody(resp)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response: %w", err)
+	}
+
+	var songLinkResp struct {
+		LinksByPlatform map[string]struct {
+			URL string `json:"url"`
+		} `json:"linksByPlatform"`
+	}
+
+	if err := json.Unmarshal(body, &songLinkResp); err != nil {
+		return nil, fmt.Errorf("failed to decode response: %w", err)
+	}
+
+	availability := &TrackAvailability{}
+
+	// Check Spotify
+	if spotifyLink, ok := songLinkResp.LinksByPlatform["spotify"]; ok && spotifyLink.URL != "" {
+		availability.SpotifyID = extractSpotifyIDFromURL(spotifyLink.URL)
+	}
+
+	// Check Tidal
+	if tidalLink, ok := songLinkResp.LinksByPlatform["tidal"]; ok && tidalLink.URL != "" {
+		availability.Tidal = true
+		availability.TidalURL = tidalLink.URL
+	}
+
+	// Check Amazon
+	if amazonLink, ok := songLinkResp.LinksByPlatform["amazonMusic"]; ok && amazonLink.URL != "" {
+		availability.Amazon = true
+		availability.AmazonURL = amazonLink.URL
+	}
+
+	// Check Deezer
+	if deezerLink, ok := songLinkResp.LinksByPlatform["deezer"]; ok && deezerLink.URL != "" {
+		availability.Deezer = true
+		availability.DeezerURL = deezerLink.URL
+		availability.DeezerID = extractDeezerIDFromURL(deezerLink.URL)
+	}
+
+	return availability, nil
+}
+
+// extractSpotifyIDFromURL extracts Spotify track ID from URL
+func extractSpotifyIDFromURL(spotifyURL string) string {
+	// URL format: https://open.spotify.com/track/0Jcij1eWd5bDMU5iPbxe2i
+	parts := strings.Split(spotifyURL, "/track/")
+	if len(parts) > 1 {
+		// Get the ID part and remove any query parameters
+		idPart := parts[1]
+		if idx := strings.Index(idPart, "?"); idx > 0 {
+			idPart = idPart[:idx]
+		}
+		return idPart
+	}
+	return ""
+}
+
+// GetSpotifyIDFromDeezer converts a Deezer track ID to Spotify track ID using SongLink
+func (s *SongLinkClient) GetSpotifyIDFromDeezer(deezerTrackID string) (string, error) {
+	availability, err := s.CheckAvailabilityFromDeezer(deezerTrackID)
+	if err != nil {
+		return "", err
+	}
+	
+	if availability.SpotifyID == "" {
+		return "", fmt.Errorf("track not found on Spotify")
+	}
+	
+	return availability.SpotifyID, nil
+}
+
+// GetTidalURLFromDeezer converts a Deezer track ID to Tidal URL using SongLink
+func (s *SongLinkClient) GetTidalURLFromDeezer(deezerTrackID string) (string, error) {
+	availability, err := s.CheckAvailabilityFromDeezer(deezerTrackID)
+	if err != nil {
+		return "", err
+	}
+	
+	if !availability.Tidal || availability.TidalURL == "" {
+		return "", fmt.Errorf("track not found on Tidal")
+	}
+	
+	return availability.TidalURL, nil
+}
+
+// GetAmazonURLFromDeezer converts a Deezer track ID to Amazon Music URL using SongLink
+func (s *SongLinkClient) GetAmazonURLFromDeezer(deezerTrackID string) (string, error) {
+	availability, err := s.CheckAvailabilityFromDeezer(deezerTrackID)
+	if err != nil {
+		return "", err
+	}
+	
+	if !availability.Amazon || availability.AmazonURL == "" {
+		return "", fmt.Errorf("track not found on Amazon Music")
+	}
+	
+	return availability.AmazonURL, nil
+}

go_backend/spotify.go

@@ -2,7 +2,6 @@ package gobackend
 
 import (
 	"context"
-	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -10,23 +9,39 @@ import (
 	"math/rand"
 	"net/http"
 	"net/url"
+	"os"
 	"strings"
 	"sync"
 	"time"
 )
 
 const (
-	spotifyTokenURL     = "https://accounts.spotify.com/api/token"
-	playlistBaseURL     = "https://api.spotify.com/v1/playlists/%s"
-	albumBaseURL        = "https://api.spotify.com/v1/albums/%s"
-	trackBaseURL        = "https://api.spotify.com/v1/tracks/%s"
-	artistBaseURL       = "https://api.spotify.com/v1/artists/%s"
-	artistAlbumsURL     = "https://api.spotify.com/v1/artists/%s/albums"
-	searchBaseURL       = "https://api.spotify.com/v1/search"
+	spotifyTokenURL = "https://accounts.spotify.com/api/token"
+	playlistBaseURL = "https://api.spotify.com/v1/playlists/%s"
+	albumBaseURL    = "https://api.spotify.com/v1/albums/%s"
+	trackBaseURL    = "https://api.spotify.com/v1/tracks/%s"
+	artistBaseURL   = "https://api.spotify.com/v1/artists/%s"
+	artistAlbumsURL = "https://api.spotify.com/v1/artists/%s/albums"
+	searchBaseURL   = "https://api.spotify.com/v1/search"
+
+	// Cache TTL settings
+	artistCacheTTL = 10 * time.Minute
+	searchCacheTTL = 5 * time.Minute
+	albumCacheTTL  = 10 * time.Minute
 )
 
 var errInvalidSpotifyURL = errors.New("invalid or unsupported Spotify URL")
 
+// cacheEntry holds cached data with expiration
+type cacheEntry struct {
+	data      interface{}
+	expiresAt time.Time
+}
+
+func (e *cacheEntry) isExpired() bool {
+	return time.Now().After(e.expiresAt)
+}
+
 // SpotifyMetadataClient handles Spotify API interactions
 type SpotifyMetadataClient struct {
 	httpClient     *http.Client
@@ -34,34 +49,98 @@ type SpotifyMetadataClient struct {
 	clientSecret   string
 	cachedToken    string
 	tokenExpiresAt time.Time
+	tokenMu        sync.Mutex // Protects token cache for concurrent access
 	rng            *rand.Rand
 	rngMu          sync.Mutex
 	userAgent      string
+
+	// Caches to reduce API calls
+	artistCache map[string]*cacheEntry // key: artistID
+	searchCache map[string]*cacheEntry // key: query+type
+	albumCache  map[string]*cacheEntry // key: albumID
+	cacheMu     sync.RWMutex
+}
+
+// Custom credentials storage (set from Flutter)
+var (
+	customClientID     string
+	customClientSecret string
+	credentialsMu      sync.RWMutex
+)
+
+// ErrNoSpotifyCredentials is returned when Spotify credentials are not configured
+var ErrNoSpotifyCredentials = errors.New("Spotify credentials not configured. Please set your own Client ID and Secret in Settings, or use Deezer as metadata source (free, no credentials required)")
+
+// SetSpotifyCredentials sets custom Spotify API credentials
+func SetSpotifyCredentials(clientID, clientSecret string) {
+	credentialsMu.Lock()
+	defer credentialsMu.Unlock()
+	customClientID = clientID
+	customClientSecret = clientSecret
+}
+
+// HasSpotifyCredentials checks if Spotify credentials are configured
+func HasSpotifyCredentials() bool {
+	credentialsMu.RLock()
+	defer credentialsMu.RUnlock()
+
+	// Check custom credentials first
+	if customClientID != "" && customClientSecret != "" {
+		return true
+	}
+
+	// Check environment variables
+	if os.Getenv("SPOTIFY_CLIENT_ID") != "" && os.Getenv("SPOTIFY_CLIENT_SECRET") != "" {
+		return true
+	}
+
+	return false
+}
+
+// getCredentials returns the current credentials or error if not configured
+func getCredentials() (string, string, error) {
+	credentialsMu.RLock()
+	defer credentialsMu.RUnlock()
+
+	// Check custom credentials first
+	if customClientID != "" && customClientSecret != "" {
+		return customClientID, customClientSecret, nil
+	}
+
+	// Check environment variables
+	clientID := os.Getenv("SPOTIFY_CLIENT_ID")
+	clientSecret := os.Getenv("SPOTIFY_CLIENT_SECRET")
+
+	if clientID != "" && clientSecret != "" {
+		return clientID, clientSecret, nil
+	}
+
+	// No credentials available
+	return "", "", ErrNoSpotifyCredentials
 }
 
 // NewSpotifyMetadataClient creates a new Spotify client
-func NewSpotifyMetadataClient() *SpotifyMetadataClient {
+// Returns error if credentials are not configured
+func NewSpotifyMetadataClient() (*SpotifyMetadataClient, error) {
+	// Get credentials - will error if not configured
+	clientID, clientSecret, err := getCredentials()
+	if err != nil {
+		return nil, err
+	}
+
 	src := rand.NewSource(time.Now().UnixNano())
 
-	// Decode credentials from base64
-	clientID := ""
-	if decoded, err := base64.StdEncoding.DecodeString("NWY1NzNjOTYyMDQ5NGJhZTg3ODkwYzBmMDhhNjAyOTM="); err == nil {
-		clientID = string(decoded)
-	}
-
-	clientSecret := ""
-	if decoded, err := base64.StdEncoding.DecodeString("MjEyNDc2ZDliMGYzNDcyZWFhNzYyZDkwYjE5YjBiYTg="); err == nil {
-		clientSecret = string(decoded)
-	}
-
 	c := &SpotifyMetadataClient{
-		httpClient:   &http.Client{Timeout: 15 * time.Second},
+		httpClient:   NewHTTPClientWithTimeout(15 * time.Second), // Use shared transport for connection pooling
 		clientID:     clientID,
 		clientSecret: clientSecret,
 		rng:          rand.New(src),
+		artistCache:  make(map[string]*cacheEntry),
+		searchCache:  make(map[string]*cacheEntry),
+		albumCache:   make(map[string]*cacheEntry),
 	}
 	c.userAgent = c.randomUserAgent()
-	return c
+	return c, nil
 }
 
 // TrackMetadata represents track information
@@ -170,6 +249,21 @@ type SearchResult struct {
 	Total  int             `json:"total"`
 }
 
+// SearchArtistResult represents an artist in search results
+type SearchArtistResult struct {
+	ID         string `json:"id"`
+	Name       string `json:"name"`
+	Images     string `json:"images"`
+	Followers  int    `json:"followers"`
+	Popularity int    `json:"popularity"`
+}
+
+// SearchAllResult represents combined search results for tracks and artists
+type SearchAllResult struct {
+	Tracks  []TrackMetadata      `json:"tracks"`
+	Artists []SearchArtistResult `json:"artists"`
+}
+
 type spotifyURI struct {
 	Type string
 	ID   string
@@ -255,14 +349,14 @@ func (c *SpotifyMetadataClient) SearchTracks(ctx context.Context, query string,
 	}
 
 	searchURL := fmt.Sprintf("%s?q=%s&type=track&limit=%d", searchBaseURL, url.QueryEscape(query), limit)
-	
+
 	var response struct {
 		Tracks struct {
 			Items []trackFull `json:"items"`
 			Total int         `json:"total"`
 		} `json:"tracks"`
 	}
-	
+
 	if err := c.getJSON(ctx, searchURL, token, &response); err != nil {
 		return nil, err
 	}
@@ -293,6 +387,98 @@ func (c *SpotifyMetadataClient) SearchTracks(ctx context.Context, query string,
 	return result, nil
 }
 
+// SearchAll searches for tracks and artists on Spotify
+func (c *SpotifyMetadataClient) SearchAll(ctx context.Context, query string, trackLimit, artistLimit int) (*SearchAllResult, error) {
+	// Create cache key
+	cacheKey := fmt.Sprintf("all:%s:%d:%d", query, trackLimit, artistLimit)
+
+	// Check cache first
+	c.cacheMu.RLock()
+	if entry, ok := c.searchCache[cacheKey]; ok && !entry.isExpired() {
+		c.cacheMu.RUnlock()
+		return entry.data.(*SearchAllResult), nil
+	}
+	c.cacheMu.RUnlock()
+
+	token, err := c.getAccessToken(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	searchURL := fmt.Sprintf("%s?q=%s&type=track,artist&limit=%d", searchBaseURL, url.QueryEscape(query), trackLimit)
+
+	var response struct {
+		Tracks struct {
+			Items []trackFull `json:"items"`
+		} `json:"tracks"`
+		Artists struct {
+			Items []struct {
+				ID        string  `json:"id"`
+				Name      string  `json:"name"`
+				Images    []image `json:"images"`
+				Followers struct {
+					Total int `json:"total"`
+				} `json:"followers"`
+				Popularity int `json:"popularity"`
+			} `json:"items"`
+		} `json:"artists"`
+	}
+
+	if err := c.getJSON(ctx, searchURL, token, &response); err != nil {
+		return nil, err
+	}
+
+	result := &SearchAllResult{
+		Tracks:  make([]TrackMetadata, 0, len(response.Tracks.Items)),
+		Artists: make([]SearchArtistResult, 0, len(response.Artists.Items)),
+	}
+
+	for _, track := range response.Tracks.Items {
+		result.Tracks = append(result.Tracks, TrackMetadata{
+			SpotifyID:   track.ID,
+			Artists:     joinArtists(track.Artists),
+			Name:        track.Name,
+			AlbumName:   track.Album.Name,
+			AlbumArtist: joinArtists(track.Album.Artists),
+			DurationMS:  track.DurationMS,
+			Images:      firstImageURL(track.Album.Images),
+			ReleaseDate: track.Album.ReleaseDate,
+			TrackNumber: track.TrackNumber,
+			TotalTracks: track.Album.TotalTracks,
+			DiscNumber:  track.DiscNumber,
+			ExternalURL: track.ExternalURL.Spotify,
+			ISRC:        track.ExternalID.ISRC,
+		})
+	}
+
+	// Limit artists to artistLimit
+	artistCount := len(response.Artists.Items)
+	if artistCount > artistLimit {
+		artistCount = artistLimit
+	}
+
+	for i := 0; i < artistCount; i++ {
+		artist := response.Artists.Items[i]
+		result.Artists = append(result.Artists, SearchArtistResult{
+			ID:         artist.ID,
+			Name:       artist.Name,
+			Images:     firstImageURL(artist.Images),
+			Followers:  artist.Followers.Total,
+			Popularity: artist.Popularity,
+		})
+	}
+
+	// Store in cache
+	c.cacheMu.Lock()
+	c.searchCache[cacheKey] = &cacheEntry{
+		data:      result,
+		expiresAt: time.Now().Add(searchCacheTTL),
+	}
+	c.cacheMu.Unlock()
+
+	return result, nil
+}
+
 func (c *SpotifyMetadataClient) fetchTrack(ctx context.Context, trackID, token string) (*TrackResponse, error) {
 	var data trackFull
 	if err := c.getJSON(ctx, fmt.Sprintf(trackBaseURL, trackID), token, &data); err != nil {
@@ -319,6 +505,25 @@ func (c *SpotifyMetadataClient) fetchTrack(ctx context.Context, trackID, token s
 }
 
 func (c *SpotifyMetadataClient) fetchAlbum(ctx context.Context, albumID, token string) (*AlbumResponsePayload, error) {
+	// Check cache first
+	c.cacheMu.RLock()
+	if entry, ok := c.albumCache[albumID]; ok && !entry.isExpired() {
+		c.cacheMu.RUnlock()
+		return entry.data.(*AlbumResponsePayload), nil
+	}
+	c.cacheMu.RUnlock()
+
+	// Track item structure for pagination
+	type trackItem struct {
+		ID          string      `json:"id"`
+		Name        string      `json:"name"`
+		DurationMS  int         `json:"duration_ms"`
+		TrackNumber int         `json:"track_number"`
+		DiscNumber  int         `json:"disc_number"`
+		ExternalURL externalURL `json:"external_urls"`
+		Artists     []artist    `json:"artists"`
+	}
+
 	var data struct {
 		Name        string   `json:"name"`
 		ReleaseDate string   `json:"release_date"`
@@ -326,15 +531,8 @@ func (c *SpotifyMetadataClient) fetchAlbum(ctx context.Context, albumID, token s
 		Images      []image  `json:"images"`
 		Artists     []artist `json:"artists"`
 		Tracks      struct {
-			Items []struct {
-				ID          string      `json:"id"`
-				Name        string      `json:"name"`
-				DurationMS  int         `json:"duration_ms"`
-				TrackNumber int         `json:"track_number"`
-				DiscNumber  int         `json:"disc_number"`
-				ExternalURL externalURL `json:"external_urls"`
-				Artists     []artist    `json:"artists"`
-			} `json:"items"`
+			Items []trackItem `json:"items"`
+			Next  string      `json:"next"`
 		} `json:"tracks"`
 	}
 
@@ -351,11 +549,39 @@ func (c *SpotifyMetadataClient) fetchAlbum(ctx context.Context, albumID, token s
 		Images:      albumImage,
 	}
 
-	tracks := make([]AlbumTrackMetadata, 0, len(data.Tracks.Items))
-	for _, item := range data.Tracks.Items {
-		// Fetch ISRC for each track
-		isrc := c.fetchTrackISRC(ctx, item.ID, token)
-		
+	// Collect all tracks (including paginated)
+	allTrackItems := data.Tracks.Items
+	nextURL := data.Tracks.Next
+
+	// Fetch remaining tracks using pagination (no limit)
+	for nextURL != "" {
+		var pageData struct {
+			Items []trackItem `json:"items"`
+			Next  string      `json:"next"`
+		}
+		if err := c.getJSON(ctx, nextURL, token, &pageData); err != nil {
+			fmt.Printf("[Spotify] Warning: failed to fetch album tracks page: %v\n", err)
+			break
+		}
+		allTrackItems = append(allTrackItems, pageData.Items...)
+		nextURL = pageData.Next
+	}
+
+	fmt.Printf("[Spotify] Album has %d tracks (total: %d)\n", len(allTrackItems), data.TotalTracks)
+
+	// Collect track IDs for parallel ISRC fetching
+	trackIDs := make([]string, len(allTrackItems))
+	for i, item := range allTrackItems {
+		trackIDs[i] = item.ID
+	}
+
+	// Fetch ISRCs in parallel for ALL tracks (like Deezer implementation)
+	isrcMap := c.fetchISRCsParallel(ctx, trackIDs, token)
+
+	tracks := make([]AlbumTrackMetadata, 0, len(allTrackItems))
+	for _, item := range allTrackItems {
+		isrc := isrcMap[item.ID]
+
 		tracks = append(tracks, AlbumTrackMetadata{
 			SpotifyID:   item.ID,
 			Artists:     joinArtists(item.Artists),
@@ -374,13 +600,65 @@ func (c *SpotifyMetadataClient) fetchAlbum(ctx context.Context, albumID, token s
 		})
 	}
 
-	return &AlbumResponsePayload{
+	result := &AlbumResponsePayload{
 		AlbumInfo: info,
 		TrackList: tracks,
-	}, nil
+	}
+
+	// Store in cache
+	c.cacheMu.Lock()
+	c.albumCache[albumID] = &cacheEntry{
+		data:      result,
+		expiresAt: time.Now().Add(albumCacheTTL),
+	}
+	c.cacheMu.Unlock()
+
+	return result, nil
+}
+
+// fetchISRCsParallel fetches ISRCs for multiple tracks in parallel
+// Similar to Deezer implementation for consistency
+func (c *SpotifyMetadataClient) fetchISRCsParallel(ctx context.Context, trackIDs []string, token string) map[string]string {
+	const maxParallelISRC = 10 // Max concurrent ISRC fetches
+
+	result := make(map[string]string)
+	var resultMu sync.Mutex
+
+	if len(trackIDs) == 0 {
+		return result
+	}
+
+	// Use semaphore to limit concurrent requests
+	sem := make(chan struct{}, maxParallelISRC)
+	var wg sync.WaitGroup
+
+	for _, trackID := range trackIDs {
+		wg.Add(1)
+		go func(id string) {
+			defer wg.Done()
+
+			// Acquire semaphore
+			select {
+			case sem <- struct{}{}:
+				defer func() { <-sem }()
+			case <-ctx.Done():
+				return
+			}
+
+			isrc := c.fetchTrackISRC(ctx, id, token)
+
+			resultMu.Lock()
+			result[id] = isrc
+			resultMu.Unlock()
+		}(trackID)
+	}
+
+	wg.Wait()
+	return result
 }
 
 func (c *SpotifyMetadataClient) fetchPlaylist(ctx context.Context, playlistID, token string) (*PlaylistResponsePayload, error) {
+	// First request to get playlist info and first batch of tracks
 	var data struct {
 		Name   string  `json:"name"`
 		Images []image `json:"images"`
@@ -391,7 +669,8 @@ func (c *SpotifyMetadataClient) fetchPlaylist(ctx context.Context, playlistID, t
 			Items []struct {
 				Track *trackFull `json:"track"`
 			} `json:"items"`
-			Total int `json:"total"`
+			Total int    `json:"total"`
+			Next  string `json:"next"`
 		} `json:"tracks"`
 	}
 
@@ -405,7 +684,10 @@ func (c *SpotifyMetadataClient) fetchPlaylist(ctx context.Context, playlistID, t
 	info.Owner.Name = data.Name
 	info.Owner.Images = firstImageURL(data.Images)
 
-	tracks := make([]AlbumTrackMetadata, 0, len(data.Tracks.Items))
+	// Pre-allocate with expected capacity
+	tracks := make([]AlbumTrackMetadata, 0, data.Tracks.Total)
+
+	// Add first batch of tracks
 	for _, item := range data.Tracks.Items {
 		if item.Track == nil {
 			continue
@@ -429,6 +711,51 @@ func (c *SpotifyMetadataClient) fetchPlaylist(ctx context.Context, playlistID, t
 		})
 	}
 
+	// Fetch remaining tracks using pagination (NO LIMIT - fetch all tracks)
+	nextURL := data.Tracks.Next
+
+	for nextURL != "" {
+		var pageData struct {
+			Items []struct {
+				Track *trackFull `json:"track"`
+			} `json:"items"`
+			Next string `json:"next"`
+		}
+
+		if err := c.getJSON(ctx, nextURL, token, &pageData); err != nil {
+			// Log error but return what we have so far
+			fmt.Printf("[Spotify] Warning: failed to fetch page, returning %d tracks: %v\n", len(tracks), err)
+			break
+		}
+
+		for _, item := range pageData.Items {
+			if item.Track == nil {
+				continue
+			}
+			tracks = append(tracks, AlbumTrackMetadata{
+				SpotifyID:   item.Track.ID,
+				Artists:     joinArtists(item.Track.Artists),
+				Name:        item.Track.Name,
+				AlbumName:   item.Track.Album.Name,
+				AlbumArtist: joinArtists(item.Track.Album.Artists),
+				DurationMS:  item.Track.DurationMS,
+				Images:      firstImageURL(item.Track.Album.Images),
+				ReleaseDate: item.Track.Album.ReleaseDate,
+				TrackNumber: item.Track.TrackNumber,
+				TotalTracks: item.Track.Album.TotalTracks,
+				DiscNumber:  item.Track.DiscNumber,
+				ExternalURL: item.Track.ExternalURL.Spotify,
+				ISRC:        item.Track.ExternalID.ISRC,
+				AlbumID:     item.Track.Album.ID,
+				AlbumURL:    item.Track.Album.ExternalURL.Spotify,
+			})
+		}
+
+		nextURL = pageData.Next
+	}
+
+	fmt.Printf("[Spotify] Fetched %d tracks from playlist (total: %d)\n", len(tracks), data.Tracks.Total)
+
 	return &PlaylistResponsePayload{
 		PlaylistInfo: info,
 		TrackList:    tracks,
@@ -436,12 +763,20 @@ func (c *SpotifyMetadataClient) fetchPlaylist(ctx context.Context, playlistID, t
 }
 
 func (c *SpotifyMetadataClient) fetchArtist(ctx context.Context, artistID, token string) (*ArtistResponsePayload, error) {
+	// Check cache first
+	c.cacheMu.RLock()
+	if entry, ok := c.artistCache[artistID]; ok && !entry.isExpired() {
+		c.cacheMu.RUnlock()
+		return entry.data.(*ArtistResponsePayload), nil
+	}
+	c.cacheMu.RUnlock()
+
 	// Fetch artist info
 	var artistData struct {
-		ID         string  `json:"id"`
-		Name       string  `json:"name"`
-		Images     []image `json:"images"`
-		Followers  struct {
+		ID        string  `json:"id"`
+		Name      string  `json:"name"`
+		Images    []image `json:"images"`
+		Followers struct {
 			Total int `json:"total"`
 		} `json:"followers"`
 		Popularity int `json:"popularity"`
@@ -511,10 +846,20 @@ func (c *SpotifyMetadataClient) fetchArtist(ctx context.Context, artistID, token
 		}
 	}
 
-	return &ArtistResponsePayload{
+	result := &ArtistResponsePayload{
 		ArtistInfo: artistInfo,
 		Albums:     albums,
-	}, nil
+	}
+
+	// Store in cache
+	c.cacheMu.Lock()
+	c.artistCache[artistID] = &cacheEntry{
+		data:      result,
+		expiresAt: time.Now().Add(artistCacheTTL),
+	}
+	c.cacheMu.Unlock()
+
+	return result, nil
 }
 
 func (c *SpotifyMetadataClient) fetchTrackISRC(ctx context.Context, trackID, token string) string {
@@ -577,8 +922,16 @@ func (c *SpotifyMetadataClient) getJSON(ctx context.Context, endpoint, token str
 		return err
 	}
 
+	// Set headers (same as PC version baseHeaders)
 	req.Header.Set("User-Agent", c.userAgent)
 	req.Header.Set("Accept", "application/json")
+	req.Header.Set("Accept-Language", "en-US,en;q=0.9")
+	req.Header.Set("sec-ch-ua-platform", "\"Windows\"")
+	req.Header.Set("sec-fetch-dest", "empty")
+	req.Header.Set("sec-fetch-mode", "cors")
+	req.Header.Set("sec-fetch-site", "same-origin")
+	req.Header.Set("Referer", "https://open.spotify.com/")
+	req.Header.Set("Origin", "https://open.spotify.com")
 	if token != "" {
 		req.Header.Set("Authorization", "Bearer "+token)
 	}
@@ -605,13 +958,23 @@ func (c *SpotifyMetadataClient) randomUserAgent() string {
 	c.rngMu.Lock()
 	defer c.rngMu.Unlock()
 
-	chromeMajor := 80 + c.rng.Intn(25)
-	chromeBuild := 3000 + c.rng.Intn(1500)
-	chromePatch := 60 + c.rng.Intn(65)
+	// Use Mac User-Agent format (same as PC version)
+	macMajor := c.rng.Intn(4) + 11         // 11-14
+	macMinor := c.rng.Intn(5) + 4          // 4-8
+	webkitMajor := c.rng.Intn(7) + 530     // 530-536
+	webkitMinor := c.rng.Intn(7) + 30      // 30-36
+	chromeMajor := c.rng.Intn(25) + 80     // 80-104
+	chromeBuild := c.rng.Intn(1500) + 3000 // 3000-4499
+	chromePatch := c.rng.Intn(65) + 60     // 60-124
+	safariMajor := c.rng.Intn(7) + 530     // 530-536
+	safariMinor := c.rng.Intn(6) + 30      // 30-35
 
 	return fmt.Sprintf(
-		"Mozilla/5.0 (Linux; Android 12) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/%d.0.%d.%d Mobile Safari/537.36",
+		"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_%d_%d) AppleWebKit/%d.%d (KHTML, like Gecko) Chrome/%d.0.%d.%d Safari/%d.%d",
+		macMajor, macMinor,
+		webkitMajor, webkitMinor,
 		chromeMajor, chromeBuild, chromePatch,
+		safariMajor, safariMinor,
 	)
 }
 

ios/Runner.xcodeproj/project.pbxproj

@@ -427,7 +427,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
-				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = YES;
+				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = AppIcon;
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
 				CLANG_CXX_LIBRARY = "libc++";
@@ -484,7 +484,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
-				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = YES;
+				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = AppIcon;
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
 				CLANG_CXX_LIBRARY = "libc++";

ios/Runner/AppDelegate.swift

@@ -66,6 +66,15 @@ import Gobackend  // Import Go framework
             if let error = error { throw error }
             return response
             
+        case "searchSpotifyAll":
+            let args = call.arguments as! [String: Any]
+            let query = args["query"] as! String
+            let trackLimit = args["track_limit"] as? Int ?? 15
+            let artistLimit = args["artist_limit"] as? Int ?? 3
+            let response = GobackendSearchSpotifyAll(query, Int(trackLimit), Int(artistLimit), &error)
+            if let error = error { throw error }
+            return response
+            
         case "checkAvailability":
             let args = call.arguments as! [String: Any]
             let spotifyId = args["spotify_id"] as! String
@@ -155,7 +164,8 @@ import Gobackend  // Import Go framework
             let spotifyId = args["spotify_id"] as! String
             let trackName = args["track_name"] as! String
             let artistName = args["artist_name"] as! String
-            let response = GobackendGetLyricsLRC(spotifyId, trackName, artistName, &error)
+            let filePath = args["file_path"] as? String ?? ""
+            let response = GobackendGetLyricsLRC(spotifyId, trackName, artistName, filePath, &error)
             if let error = error { throw error }
             return response
             
@@ -171,6 +181,323 @@ import Gobackend  // Import Go framework
             GobackendCleanupConnections()
             return nil
             
+        case "readFileMetadata":
+            let args = call.arguments as! [String: Any]
+            let filePath = args["file_path"] as! String
+            let response = GobackendReadFileMetadata(filePath, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "searchDeezerAll":
+            let args = call.arguments as! [String: Any]
+            let query = args["query"] as! String
+            let trackLimit = args["track_limit"] as? Int ?? 15
+            let artistLimit = args["artist_limit"] as? Int ?? 3
+            let response = GobackendSearchDeezerAll(query, Int(trackLimit), Int(artistLimit), &error)
+            if let error = error { throw error }
+            return response
+
+        case "getDeezerMetadata":
+            let args = call.arguments as! [String: Any]
+            let resourceType = args["resource_type"] as! String
+            let resourceId = args["resource_id"] as! String
+            let response = GobackendGetDeezerMetadata(resourceType, resourceId, &error)
+            if let error = error { throw error }
+            return response
+
+        case "parseDeezerUrl":
+            let args = call.arguments as! [String: Any]
+            let url = args["url"] as! String
+            let response = GobackendParseDeezerURLExport(url, &error)
+            if let error = error { throw error }
+            return response
+
+        case "searchDeezerByISRC":
+            let args = call.arguments as! [String: Any]
+            let isrc = args["isrc"] as! String
+            let response = GobackendSearchDeezerByISRC(isrc, &error)
+            if let error = error { throw error }
+            return response
+
+        case "convertSpotifyToDeezer":
+            let args = call.arguments as! [String: Any]
+            let resourceType = args["resource_type"] as! String
+            let spotifyId = args["spotify_id"] as! String
+            let response = GobackendConvertSpotifyToDeezer(resourceType, spotifyId, &error)
+            if let error = error { throw error }
+            return response
+
+        case "getSpotifyMetadataWithFallback":
+            let args = call.arguments as! [String: Any]
+            let url = args["url"] as! String
+            let response = GobackendGetSpotifyMetadataWithDeezerFallback(url, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "preWarmTrackCache":
+            let args = call.arguments as! [String: Any]
+            let tracksJson = args["tracks"] as! String
+            let _ = GobackendPreWarmTrackCacheJSON(tracksJson, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "getTrackCacheSize":
+            let response = GobackendGetTrackCacheSize()
+            return response
+            
+        case "clearTrackCache":
+            GobackendClearTrackCache()
+            return nil
+            
+        case "setSpotifyCredentials":
+            let args = call.arguments as! [String: Any]
+            let clientId = args["client_id"] as! String
+            let clientSecret = args["client_secret"] as! String
+            GobackendSetSpotifyAPICredentials(clientId, clientSecret)
+            return nil
+            
+        case "hasSpotifyCredentials":
+            let hasCredentials = GobackendCheckSpotifyCredentials()
+            return hasCredentials
+            
+        // Log methods
+        case "getLogs":
+            let response = GobackendGetLogs()
+            return response
+            
+        case "getLogsSince":
+            let args = call.arguments as! [String: Any]
+            let index = args["index"] as? Int ?? 0
+            let response = GobackendGetLogsSince(Int(index))
+            return response
+            
+        case "clearLogs":
+            GobackendClearLogs()
+            return nil
+            
+        case "getLogCount":
+            let response = GobackendGetLogCount()
+            return response
+            
+        case "setLoggingEnabled":
+            let args = call.arguments as! [String: Any]
+            let enabled = args["enabled"] as? Bool ?? false
+            GobackendSetLoggingEnabled(enabled)
+            return nil
+            
+        // Extension System methods
+        case "initExtensionSystem":
+            let args = call.arguments as! [String: Any]
+            let extensionsDir = args["extensions_dir"] as! String
+            let dataDir = args["data_dir"] as! String
+            GobackendInitExtensionSystem(extensionsDir, dataDir, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "loadExtensionsFromDir":
+            let args = call.arguments as! [String: Any]
+            let dirPath = args["dir_path"] as! String
+            let response = GobackendLoadExtensionsFromDir(dirPath, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "loadExtensionFromPath":
+            let args = call.arguments as! [String: Any]
+            let filePath = args["file_path"] as! String
+            let response = GobackendLoadExtensionFromPath(filePath, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "unloadExtension":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            GobackendUnloadExtensionByID(extensionId, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "getInstalledExtensions":
+            let response = GobackendGetInstalledExtensions(&error)
+            if let error = error { throw error }
+            return response
+            
+        case "setExtensionEnabled":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let enabled = args["enabled"] as? Bool ?? false
+            GobackendSetExtensionEnabledByID(extensionId, enabled, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "setProviderPriority":
+            let args = call.arguments as! [String: Any]
+            let priorityJson = args["priority"] as! String
+            GobackendSetProviderPriorityJSON(priorityJson, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "getProviderPriority":
+            let response = GobackendGetProviderPriorityJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        case "setMetadataProviderPriority":
+            let args = call.arguments as! [String: Any]
+            let priorityJson = args["priority"] as! String
+            GobackendSetMetadataProviderPriorityJSON(priorityJson, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "getMetadataProviderPriority":
+            let response = GobackendGetMetadataProviderPriorityJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        case "getExtensionSettings":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let response = GobackendGetExtensionSettingsJSON(extensionId, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "setExtensionSettings":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let settingsJson = args["settings"] as! String
+            GobackendSetExtensionSettingsJSON(extensionId, settingsJson, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "searchTracksWithExtensions":
+            let args = call.arguments as! [String: Any]
+            let query = args["query"] as! String
+            let limit = args["limit"] as? Int ?? 20
+            let response = GobackendSearchTracksWithExtensionsJSON(query, Int(limit), &error)
+            if let error = error { throw error }
+            return response
+            
+        case "downloadWithExtensions":
+            let requestJson = call.arguments as! String
+            let response = GobackendDownloadWithExtensionsJSON(requestJson, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "removeExtension":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            GobackendRemoveExtensionByID(extensionId, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "upgradeExtension":
+            let args = call.arguments as! [String: Any]
+            let filePath = args["file_path"] as! String
+            let response = GobackendUpgradeExtensionFromPath(filePath, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "checkExtensionUpgrade":
+            let args = call.arguments as! [String: Any]
+            let filePath = args["file_path"] as! String
+            let response = GobackendCheckExtensionUpgradeFromPath(filePath, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "cleanupExtensions":
+            GobackendCleanupExtensions()
+            return nil
+            
+        // Extension Auth API
+        case "getExtensionPendingAuth":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let response = GobackendGetExtensionPendingAuthJSON(extensionId, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "setExtensionAuthCode":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let authCode = args["auth_code"] as! String
+            GobackendSetExtensionAuthCodeByID(extensionId, authCode)
+            return nil
+            
+        case "setExtensionTokens":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let accessToken = args["access_token"] as! String
+            let refreshToken = args["refresh_token"] as? String ?? ""
+            let expiresIn = args["expires_in"] as? Int ?? 0
+            GobackendSetExtensionTokensByID(extensionId, accessToken, refreshToken, Int(expiresIn))
+            return nil
+            
+        case "clearExtensionPendingAuth":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            GobackendClearExtensionPendingAuthByID(extensionId)
+            return nil
+            
+        case "isExtensionAuthenticated":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let response = GobackendIsExtensionAuthenticatedByID(extensionId)
+            return response
+            
+        case "getAllPendingAuthRequests":
+            let response = GobackendGetAllPendingAuthRequestsJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        // Extension FFmpeg API
+        case "getPendingFFmpegCommand":
+            let args = call.arguments as! [String: Any]
+            let commandId = args["command_id"] as! String
+            let response = GobackendGetPendingFFmpegCommandJSON(commandId, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "setFFmpegCommandResult":
+            let args = call.arguments as! [String: Any]
+            let commandId = args["command_id"] as! String
+            let success = args["success"] as? Bool ?? false
+            let output = args["output"] as? String ?? ""
+            let errorMsg = args["error"] as? String ?? ""
+            GobackendSetFFmpegCommandResult(commandId, success, output, errorMsg)
+            return nil
+            
+        case "getAllPendingFFmpegCommands":
+            let response = GobackendGetAllPendingFFmpegCommandsJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        // Extension Custom Search API
+        case "customSearchWithExtension":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let query = args["query"] as! String
+            let optionsJson = args["options"] as? String ?? ""
+            let response = GobackendCustomSearchWithExtensionJSON(extensionId, query, optionsJson, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "getSearchProviders":
+            let response = GobackendGetSearchProvidersJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        // Extension Post-Processing API
+        case "runPostProcessing":
+            let args = call.arguments as! [String: Any]
+            let filePath = args["file_path"] as! String
+            let metadataJson = args["metadata"] as? String ?? ""
+            let response = GobackendRunPostProcessingJSON(filePath, metadataJson, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "getPostProcessingProviders":
+            let response = GobackendGetPostProcessingProvidersJSON(&error)
+            if let error = error { throw error }
+            return response
+            
         default:
             throw NSError(
                 domain: "SpotiFLAC",

ios/Runner/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -1,122 +1 @@
-{
-  "images" : [
-    {
-      "size" : "20x20",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-20x20@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "20x20",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-20x20@3x.png",
-      "scale" : "3x"
-    },
-    {
-      "size" : "29x29",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-29x29@1x.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "29x29",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-29x29@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "29x29",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-29x29@3x.png",
-      "scale" : "3x"
-    },
-    {
-      "size" : "40x40",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-40x40@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "40x40",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-40x40@3x.png",
-      "scale" : "3x"
-    },
-    {
-      "size" : "60x60",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-60x60@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "60x60",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-60x60@3x.png",
-      "scale" : "3x"
-    },
-    {
-      "size" : "20x20",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-20x20@1x.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "20x20",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-20x20@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "29x29",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-29x29@1x.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "29x29",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-29x29@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "40x40",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-40x40@1x.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "40x40",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-40x40@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "76x76",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-76x76@1x.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "76x76",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-76x76@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "83.5x83.5",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-83.5x83.5@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "1024x1024",
-      "idiom" : "ios-marketing",
-      "filename" : "Icon-App-1024x1024@1x.png",
-      "scale" : "1x"
-    }
-  ],
-  "info" : {
-    "version" : 1,
-    "author" : "xcode"
-  }
-}
+{"images":[{"size":"20x20","idiom":"iphone","filename":"Icon-App-20x20@2x.png","scale":"2x"},{"size":"20x20","idiom":"iphone","filename":"Icon-App-20x20@3x.png","scale":"3x"},{"size":"29x29","idiom":"iphone","filename":"Icon-App-29x29@1x.png","scale":"1x"},{"size":"29x29","idiom":"iphone","filename":"Icon-App-29x29@2x.png","scale":"2x"},{"size":"29x29","idiom":"iphone","filename":"Icon-App-29x29@3x.png","scale":"3x"},{"size":"40x40","idiom":"iphone","filename":"Icon-App-40x40@2x.png","scale":"2x"},{"size":"40x40","idiom":"iphone","filename":"Icon-App-40x40@3x.png","scale":"3x"},{"size":"57x57","idiom":"iphone","filename":"Icon-App-57x57@1x.png","scale":"1x"},{"size":"57x57","idiom":"iphone","filename":"Icon-App-57x57@2x.png","scale":"2x"},{"size":"60x60","idiom":"iphone","filename":"Icon-App-60x60@2x.png","scale":"2x"},{"size":"60x60","idiom":"iphone","filename":"Icon-App-60x60@3x.png","scale":"3x"},{"size":"20x20","idiom":"ipad","filename":"Icon-App-20x20@1x.png","scale":"1x"},{"size":"20x20","idiom":"ipad","filename":"Icon-App-20x20@2x.png","scale":"2x"},{"size":"29x29","idiom":"ipad","filename":"Icon-App-29x29@1x.png","scale":"1x"},{"size":"29x29","idiom":"ipad","filename":"Icon-App-29x29@2x.png","scale":"2x"},{"size":"40x40","idiom":"ipad","filename":"Icon-App-40x40@1x.png","scale":"1x"},{"size":"40x40","idiom":"ipad","filename":"Icon-App-40x40@2x.png","scale":"2x"},{"size":"50x50","idiom":"ipad","filename":"Icon-App-50x50@1x.png","scale":"1x"},{"size":"50x50","idiom":"ipad","filename":"Icon-App-50x50@2x.png","scale":"2x"},{"size":"72x72","idiom":"ipad","filename":"Icon-App-72x72@1x.png","scale":"1x"},{"size":"72x72","idiom":"ipad","filename":"Icon-App-72x72@2x.png","scale":"2x"},{"size":"76x76","idiom":"ipad","filename":"Icon-App-76x76@1x.png","scale":"1x"},{"size":"76x76","idiom":"ipad","filename":"Icon-App-76x76@2x.png","scale":"2x"},{"size":"83.5x83.5","idiom":"ipad","filename":"Icon-App-83.5x83.5@2x.png","scale":"2x"},{"size":"1024x1024","idiom":"ios-marketing","filename":"Icon-App-1024x1024@1x.png","scale":"1x"}],"info":{"version":1,"author":"xcode"}}

lib/constants/app_info.dart

@@ -1,10 +1,11 @@
 /// App version and info constants
 /// Update version here only - all other files will reference this
 class AppInfo {
-  static const String version = '1.6.0';
-  static const String buildNumber = '25';
+  static const String version = '3.0.0-alpha.2';
+  static const String buildNumber = '51';
   static const String fullVersion = '$version+$buildNumber';
   
+  
   static const String appName = 'SpotiFLAC';
   static const String copyright = '© 2026 SpotiFLAC';
   
@@ -14,4 +15,6 @@ class AppInfo {
   static const String githubRepo = 'zarzet/SpotiFLAC-Mobile';
   static const String githubUrl = 'https://github.com/$githubRepo';
   static const String originalGithubUrl = 'https://github.com/afkarxyz/SpotiFLAC';
+  
+  static const String kofiUrl = 'https://ko-fi.com/zarzet';
 }

lib/main.dart

@@ -1,7 +1,10 @@
+import 'dart:io';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:path_provider/path_provider.dart';
 import 'package:spotiflac_android/app.dart';
 import 'package:spotiflac_android/providers/download_queue_provider.dart';
+import 'package:spotiflac_android/providers/extension_provider.dart';
 import 'package:spotiflac_android/services/notification_service.dart';
 import 'package:spotiflac_android/services/share_intent_service.dart';
 
@@ -24,14 +27,42 @@ void main() async {
 }
 
 /// Widget to eagerly initialize providers that need to load data on startup
-class _EagerInitialization extends ConsumerWidget {
+class _EagerInitialization extends ConsumerStatefulWidget {
   const _EagerInitialization({required this.child});
   final Widget child;
 
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  ConsumerState<_EagerInitialization> createState() => _EagerInitializationState();
+}
+
+class _EagerInitializationState extends ConsumerState<_EagerInitialization> {
+  @override
+  void initState() {
+    super.initState();
+    _initializeExtensions();
+  }
+
+  Future<void> _initializeExtensions() async {
+    try {
+      final appDir = await getApplicationDocumentsDirectory();
+      final extensionsDir = '${appDir.path}/extensions';
+      final dataDir = '${appDir.path}/extension_data';
+      
+      // Create directories if needed
+      await Directory(extensionsDir).create(recursive: true);
+      await Directory(dataDir).create(recursive: true);
+      
+      // Initialize extension system
+      await ref.read(extensionProvider.notifier).initialize(extensionsDir, dataDir);
+    } catch (e) {
+      debugPrint('Failed to initialize extensions: $e');
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
     // Eagerly initialize download history provider to load from storage
     ref.watch(downloadHistoryProvider);
-    return child;
+    return widget.child;
   }
 }

lib/models/download_item.dart

@@ -7,11 +7,20 @@ part 'download_item.g.dart';
 enum DownloadStatus {
   queued,
   downloading,
+  finalizing, // Embedding metadata, cover, lyrics
   completed,
   failed,
   skipped,
 }
 
+/// Error type enum for better error handling
+enum DownloadErrorType {
+  unknown,
+  notFound,    // Track not found on any service
+  rateLimit,   // Rate limited by service
+  network,     // Network/connection error
+}
+
 @JsonSerializable()
 class DownloadItem {
   final String id;
@@ -19,8 +28,10 @@ class DownloadItem {
   final String service;
   final DownloadStatus status;
   final double progress;
+  final double speedMBps; // Download speed in MB/s
   final String? filePath;
   final String? error;
+  final DownloadErrorType? errorType;
   final DateTime createdAt;
   final String? qualityOverride; // Override quality for this specific download
 
@@ -30,8 +41,10 @@ class DownloadItem {
     required this.service,
     this.status = DownloadStatus.queued,
     this.progress = 0.0,
+    this.speedMBps = 0.0,
     this.filePath,
     this.error,
+    this.errorType,
     required this.createdAt,
     this.qualityOverride,
   });
@@ -42,8 +55,10 @@ class DownloadItem {
     String? service,
     DownloadStatus? status,
     double? progress,
+    double? speedMBps,
     String? filePath,
     String? error,
+    DownloadErrorType? errorType,
     DateTime? createdAt,
     String? qualityOverride,
   }) {
@@ -53,13 +68,31 @@ class DownloadItem {
       service: service ?? this.service,
       status: status ?? this.status,
       progress: progress ?? this.progress,
+      speedMBps: speedMBps ?? this.speedMBps,
       filePath: filePath ?? this.filePath,
       error: error ?? this.error,
+      errorType: errorType ?? this.errorType,
       createdAt: createdAt ?? this.createdAt,
       qualityOverride: qualityOverride ?? this.qualityOverride,
     );
   }
 
+  /// Get user-friendly error message based on error type
+  String get errorMessage {
+    if (error == null) return '';
+    
+    switch (errorType) {
+      case DownloadErrorType.notFound:
+        return 'Song not found on any service';
+      case DownloadErrorType.rateLimit:
+        return 'Rate limit reached, try again later';
+      case DownloadErrorType.network:
+        return 'Connection failed, check your internet';
+      default:
+        return error ?? 'An error occurred';
+    }
+  }
+
   factory DownloadItem.fromJson(Map<String, dynamic> json) =>
       _$DownloadItemFromJson(json);
   Map<String, dynamic> toJson() => _$DownloadItemToJson(this);

lib/models/download_item.g.dart

@@ -14,8 +14,10 @@ DownloadItem _$DownloadItemFromJson(Map<String, dynamic> json) => DownloadItem(
       $enumDecodeNullable(_$DownloadStatusEnumMap, json['status']) ??
       DownloadStatus.queued,
   progress: (json['progress'] as num?)?.toDouble() ?? 0.0,
+  speedMBps: (json['speedMBps'] as num?)?.toDouble() ?? 0.0,
   filePath: json['filePath'] as String?,
   error: json['error'] as String?,
+  errorType: $enumDecodeNullable(_$DownloadErrorTypeEnumMap, json['errorType']),
   createdAt: DateTime.parse(json['createdAt'] as String),
   qualityOverride: json['qualityOverride'] as String?,
 );
@@ -27,8 +29,10 @@ Map<String, dynamic> _$DownloadItemToJson(DownloadItem instance) =>
       'service': instance.service,
       'status': _$DownloadStatusEnumMap[instance.status]!,
       'progress': instance.progress,
+      'speedMBps': instance.speedMBps,
       'filePath': instance.filePath,
       'error': instance.error,
+      'errorType': _$DownloadErrorTypeEnumMap[instance.errorType],
       'createdAt': instance.createdAt.toIso8601String(),
       'qualityOverride': instance.qualityOverride,
     };
@@ -36,7 +40,15 @@ Map<String, dynamic> _$DownloadItemToJson(DownloadItem instance) =>
 const _$DownloadStatusEnumMap = {
   DownloadStatus.queued: 'queued',
   DownloadStatus.downloading: 'downloading',
+  DownloadStatus.finalizing: 'finalizing',
   DownloadStatus.completed: 'completed',
   DownloadStatus.failed: 'failed',
   DownloadStatus.skipped: 'skipped',
 };
+
+const _$DownloadErrorTypeEnumMap = {
+  DownloadErrorType.unknown: 'unknown',
+  DownloadErrorType.notFound: 'notFound',
+  DownloadErrorType.rateLimit: 'rateLimit',
+  DownloadErrorType.network: 'network',
+};

lib/models/settings.dart

@@ -14,11 +14,19 @@ class AppSettings {
   final bool isFirstLaunch;
   final int concurrentDownloads; // 1 = sequential (default), max 3
   final bool checkForUpdates; // Check for updates on app start
+  final String updateChannel; // stable, preview
   final bool hasSearchedBefore; // Hide helper text after first search
   final String folderOrganization; // none, artist, album, artist_album
-  final bool convertLyricsToRomaji; // Convert Japanese lyrics to romaji
   final String historyViewMode; // list, grid
+  final String historyFilterMode; // all, albums, singles
   final bool askQualityBeforeDownload; // Show quality picker before each download
+  final String spotifyClientId; // Custom Spotify client ID (empty = use default)
+  final String spotifyClientSecret; // Custom Spotify client secret (empty = use default)
+  final bool useCustomSpotifyCredentials; // Whether to use custom credentials (if set)
+  final String metadataSource; // spotify, deezer - source for search and metadata
+  final bool enableLogging; // Enable detailed logging for debugging
+  final bool useExtensionProviders; // Use extension providers for downloads when available
+  final String? searchProvider; // null/empty = default (Deezer/Spotify), otherwise extension ID
 
   const AppSettings({
     this.defaultService = 'tidal',
@@ -31,11 +39,19 @@ class AppSettings {
     this.isFirstLaunch = true,
     this.concurrentDownloads = 1, // Default: sequential (off)
     this.checkForUpdates = true, // Default: enabled
+    this.updateChannel = 'stable', // Default: stable releases only
     this.hasSearchedBefore = false, // Default: show helper text
     this.folderOrganization = 'none', // Default: no folder organization
-    this.convertLyricsToRomaji = false, // Default: keep original Japanese
     this.historyViewMode = 'grid', // Default: grid view
-    this.askQualityBeforeDownload = false, // Default: use preset quality
+    this.historyFilterMode = 'all', // Default: show all
+    this.askQualityBeforeDownload = true, // Default: ask quality before download
+    this.spotifyClientId = '', // Default: use built-in credentials
+    this.spotifyClientSecret = '', // Default: use built-in credentials
+    this.useCustomSpotifyCredentials = true, // Default: use custom if set
+    this.metadataSource = 'deezer', // Default: Deezer (no rate limit)
+    this.enableLogging = false, // Default: disabled for performance
+    this.useExtensionProviders = true, // Default: use extensions when available
+    this.searchProvider, // Default: null (use Deezer/Spotify)
   });
 
   AppSettings copyWith({
@@ -49,11 +65,19 @@ class AppSettings {
     bool? isFirstLaunch,
     int? concurrentDownloads,
     bool? checkForUpdates,
+    String? updateChannel,
     bool? hasSearchedBefore,
     String? folderOrganization,
-    bool? convertLyricsToRomaji,
     String? historyViewMode,
+    String? historyFilterMode,
     bool? askQualityBeforeDownload,
+    String? spotifyClientId,
+    String? spotifyClientSecret,
+    bool? useCustomSpotifyCredentials,
+    String? metadataSource,
+    bool? enableLogging,
+    bool? useExtensionProviders,
+    String? searchProvider,
   }) {
     return AppSettings(
       defaultService: defaultService ?? this.defaultService,
@@ -66,11 +90,19 @@ class AppSettings {
       isFirstLaunch: isFirstLaunch ?? this.isFirstLaunch,
       concurrentDownloads: concurrentDownloads ?? this.concurrentDownloads,
       checkForUpdates: checkForUpdates ?? this.checkForUpdates,
+      updateChannel: updateChannel ?? this.updateChannel,
       hasSearchedBefore: hasSearchedBefore ?? this.hasSearchedBefore,
       folderOrganization: folderOrganization ?? this.folderOrganization,
-      convertLyricsToRomaji: convertLyricsToRomaji ?? this.convertLyricsToRomaji,
       historyViewMode: historyViewMode ?? this.historyViewMode,
+      historyFilterMode: historyFilterMode ?? this.historyFilterMode,
       askQualityBeforeDownload: askQualityBeforeDownload ?? this.askQualityBeforeDownload,
+      spotifyClientId: spotifyClientId ?? this.spotifyClientId,
+      spotifyClientSecret: spotifyClientSecret ?? this.spotifyClientSecret,
+      useCustomSpotifyCredentials: useCustomSpotifyCredentials ?? this.useCustomSpotifyCredentials,
+      metadataSource: metadataSource ?? this.metadataSource,
+      enableLogging: enableLogging ?? this.enableLogging,
+      useExtensionProviders: useExtensionProviders ?? this.useExtensionProviders,
+      searchProvider: searchProvider ?? this.searchProvider,
     );
   }
 

lib/models/settings.g.dart

@@ -17,11 +17,20 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
   isFirstLaunch: json['isFirstLaunch'] as bool? ?? true,
   concurrentDownloads: (json['concurrentDownloads'] as num?)?.toInt() ?? 1,
   checkForUpdates: json['checkForUpdates'] as bool? ?? true,
+  updateChannel: json['updateChannel'] as String? ?? 'stable',
   hasSearchedBefore: json['hasSearchedBefore'] as bool? ?? false,
   folderOrganization: json['folderOrganization'] as String? ?? 'none',
-  convertLyricsToRomaji: json['convertLyricsToRomaji'] as bool? ?? false,
   historyViewMode: json['historyViewMode'] as String? ?? 'grid',
-  askQualityBeforeDownload: json['askQualityBeforeDownload'] as bool? ?? false,
+  historyFilterMode: json['historyFilterMode'] as String? ?? 'all',
+  askQualityBeforeDownload: json['askQualityBeforeDownload'] as bool? ?? true,
+  spotifyClientId: json['spotifyClientId'] as String? ?? '',
+  spotifyClientSecret: json['spotifyClientSecret'] as String? ?? '',
+  useCustomSpotifyCredentials:
+      json['useCustomSpotifyCredentials'] as bool? ?? true,
+  metadataSource: json['metadataSource'] as String? ?? 'deezer',
+  enableLogging: json['enableLogging'] as bool? ?? false,
+  useExtensionProviders: json['useExtensionProviders'] as bool? ?? true,
+  searchProvider: json['searchProvider'] as String?,
 );
 
 Map<String, dynamic> _$AppSettingsToJson(AppSettings instance) =>
@@ -36,9 +45,17 @@ Map<String, dynamic> _$AppSettingsToJson(AppSettings instance) =>
       'isFirstLaunch': instance.isFirstLaunch,
       'concurrentDownloads': instance.concurrentDownloads,
       'checkForUpdates': instance.checkForUpdates,
+      'updateChannel': instance.updateChannel,
       'hasSearchedBefore': instance.hasSearchedBefore,
       'folderOrganization': instance.folderOrganization,
-      'convertLyricsToRomaji': instance.convertLyricsToRomaji,
       'historyViewMode': instance.historyViewMode,
+      'historyFilterMode': instance.historyFilterMode,
       'askQualityBeforeDownload': instance.askQualityBeforeDownload,
+      'spotifyClientId': instance.spotifyClientId,
+      'spotifyClientSecret': instance.spotifyClientSecret,
+      'useCustomSpotifyCredentials': instance.useCustomSpotifyCredentials,
+      'metadataSource': instance.metadataSource,
+      'enableLogging': instance.enableLogging,
+      'useExtensionProviders': instance.useExtensionProviders,
+      'searchProvider': instance.searchProvider,
     };

lib/models/theme_settings.dart

@@ -4,6 +4,7 @@ import 'package:flutter/material.dart';
 const String kThemeModeKey = 'theme_mode';
 const String kUseDynamicColorKey = 'use_dynamic_color';
 const String kSeedColorKey = 'seed_color';
+const String kUseAmoledKey = 'use_amoled';
 
 /// Default Spotify green color for fallback
 const int kDefaultSeedColor = 0xFF1DB954;
@@ -13,11 +14,13 @@ class ThemeSettings {
   final ThemeMode themeMode;
   final bool useDynamicColor;
   final int seedColorValue;
+  final bool useAmoled; // Pure black background for OLED screens
 
   const ThemeSettings({
     this.themeMode = ThemeMode.system,
     this.useDynamicColor = true,
     this.seedColorValue = kDefaultSeedColor,
+    this.useAmoled = false,
   });
 
   /// Get seed color as Color object
@@ -28,11 +31,13 @@ class ThemeSettings {
     ThemeMode? themeMode,
     bool? useDynamicColor,
     int? seedColorValue,
+    bool? useAmoled,
   }) {
     return ThemeSettings(
       themeMode: themeMode ?? this.themeMode,
       useDynamicColor: useDynamicColor ?? this.useDynamicColor,
       seedColorValue: seedColorValue ?? this.seedColorValue,
+      useAmoled: useAmoled ?? this.useAmoled,
     );
   }
 
@@ -41,6 +46,7 @@ class ThemeSettings {
         kThemeModeKey: themeMode.name,
         kUseDynamicColorKey: useDynamicColor,
         kSeedColorKey: seedColorValue,
+        kUseAmoledKey: useAmoled,
       };
 
   /// Create from JSON map
@@ -49,6 +55,7 @@ class ThemeSettings {
       themeMode: _themeModeFromString(json[kThemeModeKey] as String?),
       useDynamicColor: json[kUseDynamicColorKey] as bool? ?? true,
       seedColorValue: json[kSeedColorKey] as int? ?? kDefaultSeedColor,
+      useAmoled: json[kUseAmoledKey] as bool? ?? false,
     );
   }
 
@@ -58,12 +65,13 @@ class ThemeSettings {
     return other is ThemeSettings &&
         other.themeMode == themeMode &&
         other.useDynamicColor == useDynamicColor &&
-        other.seedColorValue == seedColorValue;
+        other.seedColorValue == seedColorValue &&
+        other.useAmoled == useAmoled;
   }
 
   @override
   int get hashCode =>
-      themeMode.hashCode ^ useDynamicColor.hashCode ^ seedColorValue.hashCode;
+      themeMode.hashCode ^ useDynamicColor.hashCode ^ seedColorValue.hashCode ^ useAmoled.hashCode;
 }
 
 /// Helper to convert string to ThemeMode

lib/models/track.dart

@@ -16,7 +16,9 @@ class Track {
   final int? trackNumber;
   final int? discNumber;
   final String? releaseDate;
+  final String? deezerId;
   final ServiceAvailability? availability;
+  final String? source; // Extension ID that provided this track (null for built-in sources)
 
   const Track({
     required this.id,
@@ -30,11 +32,16 @@ class Track {
     this.trackNumber,
     this.discNumber,
     this.releaseDate,
+    this.deezerId,
     this.availability,
+    this.source,
   });
 
   factory Track.fromJson(Map<String, dynamic> json) => _$TrackFromJson(json);
   Map<String, dynamic> toJson() => _$TrackToJson(this);
+  
+  /// Check if this track is from an extension
+  bool get isFromExtension => source != null && source!.isNotEmpty;
 }
 
 @JsonSerializable()
@@ -42,17 +49,23 @@ class ServiceAvailability {
   final bool tidal;
   final bool qobuz;
   final bool amazon;
+  final bool deezer;
   final String? tidalUrl;
   final String? qobuzUrl;
   final String? amazonUrl;
+  final String? deezerUrl;
+  final String? deezerId;
 
   const ServiceAvailability({
     this.tidal = false,
     this.qobuz = false,
     this.amazon = false,
+    this.deezer = false,
     this.tidalUrl,
     this.qobuzUrl,
     this.amazonUrl,
+    this.deezerUrl,
+    this.deezerId,
   });
 
   factory ServiceAvailability.fromJson(Map<String, dynamic> json) =>

lib/models/track.g.dart

@@ -18,11 +18,13 @@ Track _$TrackFromJson(Map<String, dynamic> json) => Track(
   trackNumber: (json['trackNumber'] as num?)?.toInt(),
   discNumber: (json['discNumber'] as num?)?.toInt(),
   releaseDate: json['releaseDate'] as String?,
+  deezerId: json['deezerId'] as String?,
   availability: json['availability'] == null
       ? null
       : ServiceAvailability.fromJson(
           json['availability'] as Map<String, dynamic>,
         ),
+  source: json['source'] as String?,
 );
 
 Map<String, dynamic> _$TrackToJson(Track instance) => <String, dynamic>{
@@ -37,7 +39,9 @@ Map<String, dynamic> _$TrackToJson(Track instance) => <String, dynamic>{
   'trackNumber': instance.trackNumber,
   'discNumber': instance.discNumber,
   'releaseDate': instance.releaseDate,
+  'deezerId': instance.deezerId,
   'availability': instance.availability,
+  'source': instance.source,
 };
 
 ServiceAvailability _$ServiceAvailabilityFromJson(Map<String, dynamic> json) =>
@@ -45,9 +49,12 @@ ServiceAvailability _$ServiceAvailabilityFromJson(Map<String, dynamic> json) =>
       tidal: json['tidal'] as bool? ?? false,
       qobuz: json['qobuz'] as bool? ?? false,
       amazon: json['amazon'] as bool? ?? false,
+      deezer: json['deezer'] as bool? ?? false,
       tidalUrl: json['tidalUrl'] as String?,
       qobuzUrl: json['qobuzUrl'] as String?,
       amazonUrl: json['amazonUrl'] as String?,
+      deezerUrl: json['deezerUrl'] as String?,
+      deezerId: json['deezerId'] as String?,
     );
 
 Map<String, dynamic> _$ServiceAvailabilityToJson(
@@ -56,7 +63,10 @@ Map<String, dynamic> _$ServiceAvailabilityToJson(
   'tidal': instance.tidal,
   'qobuz': instance.qobuz,
   'amazon': instance.amazon,
+  'deezer': instance.deezer,
   'tidalUrl': instance.tidalUrl,
   'qobuzUrl': instance.qobuzUrl,
   'amazonUrl': instance.amazonUrl,
+  'deezerUrl': instance.deezerUrl,
+  'deezerId': instance.deezerId,
 };

lib/providers/extension_provider.dart

@@ -0,0 +1,677 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:spotiflac_android/services/platform_bridge.dart';
+import 'package:spotiflac_android/utils/logger.dart';
+import 'package:spotiflac_android/providers/settings_provider.dart';
+
+final _log = AppLogger('ExtensionProvider');
+
+/// Represents an installed extension
+class Extension {
+  final String id;
+  final String name;
+  final String displayName;
+  final String version;
+  final String author;
+  final String description;
+  final bool enabled;
+  final String status; // 'loaded', 'error', 'disabled'
+  final String? errorMessage;
+  final String? iconPath; // Path to extension icon
+  final List<String> permissions;
+  final List<ExtensionSetting> settings;
+  final List<QualityOption> qualityOptions; // Custom quality options for download providers
+  final bool hasMetadataProvider;
+  final bool hasDownloadProvider;
+  final bool skipMetadataEnrichment; // If true, use metadata from extension instead of enriching
+  final SearchBehavior? searchBehavior; // Custom search behavior
+  final TrackMatching? trackMatching; // Custom track matching
+  final PostProcessing? postProcessing; // Post-processing hooks
+
+  const Extension({
+    required this.id,
+    required this.name,
+    required this.displayName,
+    required this.version,
+    required this.author,
+    required this.description,
+    required this.enabled,
+    required this.status,
+    this.errorMessage,
+    this.iconPath,
+    this.permissions = const [],
+    this.settings = const [],
+    this.qualityOptions = const [],
+    this.hasMetadataProvider = false,
+    this.hasDownloadProvider = false,
+    this.skipMetadataEnrichment = false,
+    this.searchBehavior,
+    this.trackMatching,
+    this.postProcessing,
+  });
+
+  factory Extension.fromJson(Map<String, dynamic> json) {
+    return Extension(
+      id: json['id'] as String? ?? '',
+      name: json['name'] as String? ?? '',
+      displayName: json['display_name'] as String? ?? json['name'] as String? ?? '',
+      version: json['version'] as String? ?? '0.0.0',
+      author: json['author'] as String? ?? 'Unknown',
+      description: json['description'] as String? ?? '',
+      enabled: json['enabled'] as bool? ?? false,
+      status: json['status'] as String? ?? 'loaded',
+      errorMessage: json['error_message'] as String?,
+      iconPath: json['icon_path'] as String?,
+      permissions: (json['permissions'] as List<dynamic>?)?.cast<String>() ?? [],
+      settings: (json['settings'] as List<dynamic>?)
+          ?.map((s) => ExtensionSetting.fromJson(s as Map<String, dynamic>))
+          .toList() ?? [],
+      qualityOptions: (json['quality_options'] as List<dynamic>?)
+          ?.map((q) => QualityOption.fromJson(q as Map<String, dynamic>))
+          .toList() ?? [],
+      hasMetadataProvider: json['has_metadata_provider'] as bool? ?? false,
+      hasDownloadProvider: json['has_download_provider'] as bool? ?? false,
+      skipMetadataEnrichment: json['skip_metadata_enrichment'] as bool? ?? false,
+      searchBehavior: json['search_behavior'] != null 
+          ? SearchBehavior.fromJson(json['search_behavior'] as Map<String, dynamic>)
+          : null,
+      trackMatching: json['track_matching'] != null
+          ? TrackMatching.fromJson(json['track_matching'] as Map<String, dynamic>)
+          : null,
+      postProcessing: json['post_processing'] != null
+          ? PostProcessing.fromJson(json['post_processing'] as Map<String, dynamic>)
+          : null,
+    );
+  }
+
+  Extension copyWith({
+    String? id,
+    String? name,
+    String? displayName,
+    String? version,
+    String? author,
+    String? description,
+    bool? enabled,
+    String? status,
+    String? errorMessage,
+    String? iconPath,
+    List<String>? permissions,
+    List<ExtensionSetting>? settings,
+    List<QualityOption>? qualityOptions,
+    bool? hasMetadataProvider,
+    bool? hasDownloadProvider,
+    bool? skipMetadataEnrichment,
+    SearchBehavior? searchBehavior,
+    TrackMatching? trackMatching,
+    PostProcessing? postProcessing,
+  }) {
+    return Extension(
+      id: id ?? this.id,
+      name: name ?? this.name,
+      displayName: displayName ?? this.displayName,
+      version: version ?? this.version,
+      author: author ?? this.author,
+      description: description ?? this.description,
+      enabled: enabled ?? this.enabled,
+      status: status ?? this.status,
+      errorMessage: errorMessage ?? this.errorMessage,
+      iconPath: iconPath ?? this.iconPath,
+      permissions: permissions ?? this.permissions,
+      settings: settings ?? this.settings,
+      qualityOptions: qualityOptions ?? this.qualityOptions,
+      hasMetadataProvider: hasMetadataProvider ?? this.hasMetadataProvider,
+      hasDownloadProvider: hasDownloadProvider ?? this.hasDownloadProvider,
+      skipMetadataEnrichment: skipMetadataEnrichment ?? this.skipMetadataEnrichment,
+      searchBehavior: searchBehavior ?? this.searchBehavior,
+      trackMatching: trackMatching ?? this.trackMatching,
+      postProcessing: postProcessing ?? this.postProcessing,
+    );
+  }
+
+  bool get hasCustomSearch => searchBehavior?.enabled ?? false;
+  bool get hasCustomMatching => trackMatching?.customMatching ?? false;
+  bool get hasPostProcessing => postProcessing?.enabled ?? false;
+}
+
+/// Custom search behavior configuration
+class SearchBehavior {
+  final bool enabled;
+  final String? placeholder;
+  final bool primary;
+  final String? icon;
+  final String? thumbnailRatio; // "square" (1:1), "wide" (16:9), "portrait" (2:3)
+  final int? thumbnailWidth;
+  final int? thumbnailHeight;
+
+  const SearchBehavior({
+    required this.enabled,
+    this.placeholder,
+    this.primary = false,
+    this.icon,
+    this.thumbnailRatio,
+    this.thumbnailWidth,
+    this.thumbnailHeight,
+  });
+
+  factory SearchBehavior.fromJson(Map<String, dynamic> json) {
+    return SearchBehavior(
+      enabled: json['enabled'] as bool? ?? false,
+      placeholder: json['placeholder'] as String?,
+      primary: json['primary'] as bool? ?? false,
+      icon: json['icon'] as String?,
+      thumbnailRatio: json['thumbnailRatio'] as String?,
+      thumbnailWidth: json['thumbnailWidth'] as int?,
+      thumbnailHeight: json['thumbnailHeight'] as int?,
+    );
+  }
+
+  /// Get thumbnail size based on configuration
+  /// Returns (width, height) tuple
+  (double, double) getThumbnailSize({double defaultSize = 56}) {
+    // If custom dimensions specified, use them
+    if (thumbnailWidth != null && thumbnailHeight != null) {
+      return (thumbnailWidth!.toDouble(), thumbnailHeight!.toDouble());
+    }
+    
+    // Otherwise use ratio presets
+    switch (thumbnailRatio) {
+      case 'wide': // 16:9 - YouTube style
+        return (defaultSize * 16 / 9, defaultSize);
+      case 'portrait': // 2:3 - Poster style
+        return (defaultSize * 2 / 3, defaultSize);
+      case 'square': // 1:1 - Album art style
+      default:
+        return (defaultSize, defaultSize);
+    }
+  }
+}
+
+/// Custom track matching configuration
+class TrackMatching {
+  final bool customMatching;
+  final String? strategy; // "isrc", "name", "duration", "custom"
+  final int durationTolerance; // in seconds
+
+  const TrackMatching({
+    required this.customMatching,
+    this.strategy,
+    this.durationTolerance = 3,
+  });
+
+  factory TrackMatching.fromJson(Map<String, dynamic> json) {
+    return TrackMatching(
+      customMatching: json['customMatching'] as bool? ?? false,
+      strategy: json['strategy'] as String?,
+      durationTolerance: json['durationTolerance'] as int? ?? 3,
+    );
+  }
+}
+
+/// Post-processing configuration
+class PostProcessing {
+  final bool enabled;
+  final List<PostProcessingHook> hooks;
+
+  const PostProcessing({
+    required this.enabled,
+    this.hooks = const [],
+  });
+
+  factory PostProcessing.fromJson(Map<String, dynamic> json) {
+    return PostProcessing(
+      enabled: json['enabled'] as bool? ?? false,
+      hooks: (json['hooks'] as List<dynamic>?)
+          ?.map((h) => PostProcessingHook.fromJson(h as Map<String, dynamic>))
+          .toList() ?? [],
+    );
+  }
+}
+
+/// A post-processing hook
+class PostProcessingHook {
+  final String id;
+  final String name;
+  final String? description;
+  final bool defaultEnabled;
+  final List<String> supportedFormats;
+
+  const PostProcessingHook({
+    required this.id,
+    required this.name,
+    this.description,
+    this.defaultEnabled = false,
+    this.supportedFormats = const [],
+  });
+
+  factory PostProcessingHook.fromJson(Map<String, dynamic> json) {
+    return PostProcessingHook(
+      id: json['id'] as String? ?? '',
+      name: json['name'] as String? ?? '',
+      description: json['description'] as String?,
+      defaultEnabled: json['defaultEnabled'] as bool? ?? false,
+      supportedFormats: (json['supportedFormats'] as List<dynamic>?)?.cast<String>() ?? [],
+    );
+  }
+}
+
+/// Represents a quality option for download providers
+class QualityOption {
+  final String id;
+  final String label;
+  final String? description;
+  final List<QualitySpecificSetting> settings; // Quality-specific settings
+
+  const QualityOption({
+    required this.id,
+    required this.label,
+    this.description,
+    this.settings = const [],
+  });
+
+  factory QualityOption.fromJson(Map<String, dynamic> json) {
+    return QualityOption(
+      id: json['id'] as String? ?? '',
+      label: json['label'] as String? ?? '',
+      description: json['description'] as String?,
+      settings: (json['settings'] as List<dynamic>?)
+          ?.map((s) => QualitySpecificSetting.fromJson(s as Map<String, dynamic>))
+          .toList() ?? [],
+    );
+  }
+}
+
+/// Represents a setting that's specific to a quality option
+class QualitySpecificSetting {
+  final String key;
+  final String label;
+  final String type; // 'string', 'number', 'boolean', 'select'
+  final dynamic defaultValue;
+  final String? description;
+  final List<String>? options; // For select type
+  final bool required;
+  final bool secret;
+
+  const QualitySpecificSetting({
+    required this.key,
+    required this.label,
+    required this.type,
+    this.defaultValue,
+    this.description,
+    this.options,
+    this.required = false,
+    this.secret = false,
+  });
+
+  factory QualitySpecificSetting.fromJson(Map<String, dynamic> json) {
+    return QualitySpecificSetting(
+      key: json['key'] as String? ?? '',
+      label: json['label'] as String? ?? '',
+      type: json['type'] as String? ?? 'string',
+      defaultValue: json['default'],
+      description: json['description'] as String?,
+      options: (json['options'] as List<dynamic>?)?.cast<String>(),
+      required: json['required'] as bool? ?? false,
+      secret: json['secret'] as bool? ?? false,
+    );
+  }
+}
+
+/// Represents a setting field for an extension
+class ExtensionSetting {
+  final String key;
+  final String label;
+  final String type; // 'string', 'number', 'boolean', 'select'
+  final dynamic defaultValue;
+  final String? description;
+  final List<String>? options; // For select type
+  final bool required;
+
+  const ExtensionSetting({
+    required this.key,
+    required this.label,
+    required this.type,
+    this.defaultValue,
+    this.description,
+    this.options,
+    this.required = false,
+  });
+
+  factory ExtensionSetting.fromJson(Map<String, dynamic> json) {
+    return ExtensionSetting(
+      key: json['key'] as String? ?? '',
+      label: json['label'] as String? ?? '',
+      type: json['type'] as String? ?? 'string',
+      defaultValue: json['default'],
+      description: json['description'] as String?,
+      options: (json['options'] as List<dynamic>?)?.cast<String>(),
+      required: json['required'] as bool? ?? false,
+    );
+  }
+}
+
+/// State for extension management
+class ExtensionState {
+  final List<Extension> extensions;
+  final List<String> providerPriority;
+  final List<String> metadataProviderPriority;
+  final bool isLoading;
+  final String? error;
+  final bool isInitialized;
+
+  const ExtensionState({
+    this.extensions = const [],
+    this.providerPriority = const [],
+    this.metadataProviderPriority = const [],
+    this.isLoading = false,
+    this.error,
+    this.isInitialized = false,
+  });
+
+  ExtensionState copyWith({
+    List<Extension>? extensions,
+    List<String>? providerPriority,
+    List<String>? metadataProviderPriority,
+    bool? isLoading,
+    String? error,
+    bool? isInitialized,
+  }) {
+    return ExtensionState(
+      extensions: extensions ?? this.extensions,
+      providerPriority: providerPriority ?? this.providerPriority,
+      metadataProviderPriority: metadataProviderPriority ?? this.metadataProviderPriority,
+      isLoading: isLoading ?? this.isLoading,
+      error: error,
+      isInitialized: isInitialized ?? this.isInitialized,
+    );
+  }
+}
+
+
+/// Provider for managing extensions
+class ExtensionNotifier extends Notifier<ExtensionState> {
+  @override
+  ExtensionState build() {
+    return const ExtensionState();
+  }
+
+  /// Initialize the extension system
+  Future<void> initialize(String extensionsDir, String dataDir) async {
+    if (state.isInitialized) return;
+    
+    state = state.copyWith(isLoading: true, error: null);
+    
+    try {
+      await PlatformBridge.initExtensionSystem(extensionsDir, dataDir);
+      await loadExtensions(extensionsDir);
+      await loadProviderPriority();
+      await loadMetadataProviderPriority();
+      state = state.copyWith(isInitialized: true, isLoading: false);
+      _log.i('Extension system initialized');
+    } catch (e) {
+      _log.e('Failed to initialize extension system: $e');
+      state = state.copyWith(isLoading: false, error: e.toString());
+    }
+  }
+
+  /// Load all extensions from directory
+  Future<void> loadExtensions(String dirPath) async {
+    state = state.copyWith(isLoading: true, error: null);
+    
+    try {
+      final result = await PlatformBridge.loadExtensionsFromDir(dirPath);
+      _log.d('Load extensions result: $result');
+      await refreshExtensions();
+      state = state.copyWith(isLoading: false);
+    } catch (e) {
+      _log.e('Failed to load extensions: $e');
+      state = state.copyWith(isLoading: false, error: e.toString());
+    }
+  }
+
+  /// Refresh the list of installed extensions
+  Future<void> refreshExtensions() async {
+    try {
+      final list = await PlatformBridge.getInstalledExtensions();
+      final extensions = list.map((e) => Extension.fromJson(e)).toList();
+      state = state.copyWith(extensions: extensions);
+      _log.d('Loaded ${extensions.length} extensions');
+      
+      // Log search behavior for extensions that have it
+      for (final ext in extensions) {
+        if (ext.searchBehavior != null) {
+          _log.d('Extension ${ext.id}: thumbnailRatio=${ext.searchBehavior!.thumbnailRatio}');
+        }
+      }
+    } catch (e) {
+      _log.e('Failed to refresh extensions: $e');
+      state = state.copyWith(error: e.toString());
+    }
+  }
+
+  /// Clear any error state
+  void clearError() {
+    state = state.copyWith(error: null);
+  }
+
+  /// Install extension from file (auto-upgrades if already installed with newer version)
+  Future<bool> installExtension(String filePath) async {
+    state = state.copyWith(isLoading: true, error: null);
+    
+    try {
+      final result = await PlatformBridge.loadExtensionFromPath(filePath);
+      _log.i('Installed extension: ${result['name']}');
+      await refreshExtensions();
+      state = state.copyWith(isLoading: false);
+      return true;
+    } catch (e) {
+      _log.e('Failed to install extension: $e');
+      state = state.copyWith(isLoading: false, error: e.toString());
+      return false;
+    }
+  }
+
+  /// Check if a package file is an upgrade for an existing extension
+  /// Returns: {extension_id, current_version, new_version, can_upgrade, is_installed}
+  Future<Map<String, dynamic>> checkExtensionUpgrade(String filePath) async {
+    try {
+      return await PlatformBridge.checkExtensionUpgrade(filePath);
+    } catch (e) {
+      _log.e('Failed to check extension upgrade: $e');
+      return {'error': e.toString()};
+    }
+  }
+
+  /// Upgrade an existing extension from a new package file
+  Future<bool> upgradeExtension(String filePath) async {
+    state = state.copyWith(isLoading: true, error: null);
+    
+    try {
+      final result = await PlatformBridge.upgradeExtension(filePath);
+      _log.i('Upgraded extension: ${result['display_name']} to v${result['version']}');
+      await refreshExtensions();
+      state = state.copyWith(isLoading: false);
+      return true;
+    } catch (e) {
+      _log.e('Failed to upgrade extension: $e');
+      state = state.copyWith(isLoading: false, error: e.toString());
+      return false;
+    }
+  }
+
+  /// Uninstall/remove an extension
+  Future<bool> removeExtension(String extensionId) async {
+    state = state.copyWith(isLoading: true, error: null);
+    
+    try {
+      await PlatformBridge.removeExtension(extensionId);
+      _log.i('Removed extension: $extensionId');
+      await refreshExtensions();
+      state = state.copyWith(isLoading: false);
+      return true;
+    } catch (e) {
+      _log.e('Failed to remove extension: $e');
+      state = state.copyWith(isLoading: false, error: e.toString());
+      return false;
+    }
+  }
+
+  /// Enable or disable an extension
+  Future<void> setExtensionEnabled(String extensionId, bool enabled) async {
+    try {
+      await PlatformBridge.setExtensionEnabled(extensionId, enabled);
+      _log.d('Set extension $extensionId enabled: $enabled');
+      
+      // Get extension info before updating state
+      final ext = state.extensions.where((e) => e.id == extensionId).firstOrNull;
+      
+      // Update local state
+      final extensions = state.extensions.map((e) {
+        if (e.id == extensionId) {
+          return e.copyWith(enabled: enabled);
+        }
+        return e;
+      }).toList();
+      
+      state = state.copyWith(extensions: extensions);
+      
+      // If disabling an extension, reset related settings
+      if (!enabled && ext != null) {
+        final settings = ref.read(settingsProvider);
+        
+        // If this extension was the search provider, clear it and reset to Deezer
+        if (settings.searchProvider == extensionId) {
+          ref.read(settingsProvider.notifier).setSearchProvider(null);
+          ref.read(settingsProvider.notifier).setMetadataSource('deezer');
+          _log.d('Cleared search provider and reset to Deezer because extension $extensionId was disabled');
+        }
+        
+        // If this extension was the default download service, reset to Tidal
+        if (ext.hasDownloadProvider && settings.defaultService == extensionId) {
+          ref.read(settingsProvider.notifier).setDefaultService('tidal');
+          _log.d('Reset default service to Tidal because extension $extensionId was disabled');
+        }
+      }
+    } catch (e) {
+      _log.e('Failed to set extension enabled: $e');
+      state = state.copyWith(error: e.toString());
+    }
+  }
+
+  /// Get settings for an extension
+  Future<Map<String, dynamic>> getExtensionSettings(String extensionId) async {
+    try {
+      return await PlatformBridge.getExtensionSettings(extensionId);
+    } catch (e) {
+      _log.e('Failed to get extension settings: $e');
+      return {};
+    }
+  }
+
+  /// Update settings for an extension
+  Future<void> setExtensionSettings(String extensionId, Map<String, dynamic> settings) async {
+    try {
+      await PlatformBridge.setExtensionSettings(extensionId, settings);
+      _log.d('Updated settings for extension: $extensionId');
+    } catch (e) {
+      _log.e('Failed to set extension settings: $e');
+      state = state.copyWith(error: e.toString());
+    }
+  }
+
+  /// Load provider priority order
+  Future<void> loadProviderPriority() async {
+    try {
+      final priority = await PlatformBridge.getProviderPriority();
+      state = state.copyWith(providerPriority: priority);
+    } catch (e) {
+      _log.e('Failed to load provider priority: $e');
+    }
+  }
+
+  /// Set provider priority order
+  Future<void> setProviderPriority(List<String> priority) async {
+    try {
+      await PlatformBridge.setProviderPriority(priority);
+      state = state.copyWith(providerPriority: priority);
+      _log.d('Updated provider priority: $priority');
+    } catch (e) {
+      _log.e('Failed to set provider priority: $e');
+      state = state.copyWith(error: e.toString());
+    }
+  }
+
+  /// Load metadata provider priority order
+  Future<void> loadMetadataProviderPriority() async {
+    try {
+      final priority = await PlatformBridge.getMetadataProviderPriority();
+      state = state.copyWith(metadataProviderPriority: priority);
+    } catch (e) {
+      _log.e('Failed to load metadata provider priority: $e');
+    }
+  }
+
+  /// Set metadata provider priority order
+  Future<void> setMetadataProviderPriority(List<String> priority) async {
+    try {
+      await PlatformBridge.setMetadataProviderPriority(priority);
+      state = state.copyWith(metadataProviderPriority: priority);
+      _log.d('Updated metadata provider priority: $priority');
+    } catch (e) {
+      _log.e('Failed to set metadata provider priority: $e');
+      state = state.copyWith(error: e.toString());
+    }
+  }
+
+  /// Cleanup all extensions (call on app close)
+  Future<void> cleanup() async {
+    try {
+      await PlatformBridge.cleanupExtensions();
+      _log.d('Extensions cleaned up');
+    } catch (e) {
+      _log.e('Failed to cleanup extensions: $e');
+    }
+  }
+
+  /// Get extension by ID
+  Extension? getExtension(String extensionId) {
+    try {
+      return state.extensions.firstWhere((ext) => ext.id == extensionId);
+    } catch (_) {
+      return null;
+    }
+  }
+
+  /// Get all enabled extensions
+  List<Extension> get enabledExtensions {
+    return state.extensions.where((ext) => ext.enabled).toList();
+  }
+
+  /// Get all download providers (built-in + extensions)
+  List<String> getAllDownloadProviders() {
+    final providers = ['tidal', 'qobuz', 'amazon'];
+    for (final ext in state.extensions) {
+      if (ext.enabled && ext.hasDownloadProvider) {
+        providers.add(ext.id);
+      }
+    }
+    return providers;
+  }
+
+  /// Get all metadata providers (built-in + extensions)
+  List<String> getAllMetadataProviders() {
+    final providers = ['deezer', 'spotify'];
+    for (final ext in state.extensions) {
+      if (ext.enabled && ext.hasMetadataProvider) {
+        providers.add(ext.id);
+      }
+    }
+    return providers;
+  }
+  /// Get all extensions that provide custom search
+  List<Extension> get searchProviders {
+    return state.extensions.where((ext) => ext.enabled && ext.hasCustomSearch).toList();
+  }
+}
+
+final extensionProvider = NotifierProvider<ExtensionNotifier, ExtensionState>(
+  ExtensionNotifier.new,
+);

lib/providers/settings_provider.dart

@@ -2,8 +2,12 @@ import 'dart:convert';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 import 'package:spotiflac_android/models/settings.dart';
+import 'package:spotiflac_android/services/platform_bridge.dart';
+import 'package:spotiflac_android/utils/logger.dart';
 
 const _settingsKey = 'app_settings';
+const _migrationVersionKey = 'settings_migration_version';
+const _currentMigrationVersion = 1;
 
 class SettingsNotifier extends Notifier<AppSettings> {
   @override
@@ -17,6 +21,35 @@ class SettingsNotifier extends Notifier<AppSettings> {
     final json = prefs.getString(_settingsKey);
     if (json != null) {
       state = AppSettings.fromJson(jsonDecode(json));
+      
+      // Run migrations if needed
+      await _runMigrations(prefs);
+      
+      // Apply Spotify credentials to Go backend on load
+      _applySpotifyCredentials();
+      
+      // Sync logging state
+      LogBuffer.loggingEnabled = state.enableLogging;
+    }
+  }
+
+  /// Run one-time migrations for settings
+  Future<void> _runMigrations(SharedPreferences prefs) async {
+    final lastMigration = prefs.getInt(_migrationVersionKey) ?? 0;
+    
+    if (lastMigration < 1) {
+      // Migration 1: Set metadataSource to 'deezer' for existing users
+      // Only apply if user hasn't enabled custom Spotify credentials
+      // (users with custom credentials likely prefer Spotify)
+      if (!state.useCustomSpotifyCredentials) {
+        state = state.copyWith(metadataSource: 'deezer');
+        await _saveSettings();
+      }
+    }
+    
+    // Save current migration version
+    if (lastMigration < _currentMigrationVersion) {
+      await prefs.setInt(_migrationVersionKey, _currentMigrationVersion);
     }
   }
 
@@ -25,6 +58,20 @@ class SettingsNotifier extends Notifier<AppSettings> {
     await prefs.setString(_settingsKey, jsonEncode(state.toJson()));
   }
 
+  /// Apply current Spotify credentials to Go backend
+  Future<void> _applySpotifyCredentials() async {
+    // Only apply if both fields are set
+    if (state.spotifyClientId.isNotEmpty && 
+        state.spotifyClientSecret.isNotEmpty) {
+      await PlatformBridge.setSpotifyCredentials(
+        state.spotifyClientId,
+        state.spotifyClientSecret,
+      );
+    }
+    // Note: If credentials are empty, Spotify API will return error
+    // User should use Deezer as metadata source instead
+  }
+
   void setDefaultService(String service) {
     state = state.copyWith(defaultService: service);
     _saveSettings();
@@ -77,6 +124,11 @@ class SettingsNotifier extends Notifier<AppSettings> {
     _saveSettings();
   }
 
+  void setUpdateChannel(String channel) {
+    state = state.copyWith(updateChannel: channel);
+    _saveSettings();
+  }
+
   void setHasSearchedBefore() {
     if (!state.hasSearchedBefore) {
       state = state.copyWith(hasSearchedBefore: true);
@@ -89,13 +141,13 @@ class SettingsNotifier extends Notifier<AppSettings> {
     _saveSettings();
   }
 
-  void setConvertLyricsToRomaji(bool enabled) {
-    state = state.copyWith(convertLyricsToRomaji: enabled);
+  void setHistoryViewMode(String mode) {
+    state = state.copyWith(historyViewMode: mode);
     _saveSettings();
   }
 
-  void setHistoryViewMode(String mode) {
-    state = state.copyWith(historyViewMode: mode);
+  void setHistoryFilterMode(String mode) {
+    state = state.copyWith(historyFilterMode: mode);
     _saveSettings();
   }
 
@@ -103,6 +155,62 @@ class SettingsNotifier extends Notifier<AppSettings> {
     state = state.copyWith(askQualityBeforeDownload: enabled);
     _saveSettings();
   }
+
+  void setSpotifyClientId(String clientId) {
+    state = state.copyWith(spotifyClientId: clientId);
+    _saveSettings();
+  }
+
+  void setSpotifyClientSecret(String clientSecret) {
+    state = state.copyWith(spotifyClientSecret: clientSecret);
+    _saveSettings();
+  }
+
+  void setSpotifyCredentials(String clientId, String clientSecret) {
+    state = state.copyWith(
+      spotifyClientId: clientId,
+      spotifyClientSecret: clientSecret,
+    );
+    _saveSettings();
+    _applySpotifyCredentials();
+  }
+
+  void clearSpotifyCredentials() {
+    state = state.copyWith(
+      spotifyClientId: '',
+      spotifyClientSecret: '',
+    );
+    _saveSettings();
+    _applySpotifyCredentials();
+  }
+
+  void setUseCustomSpotifyCredentials(bool enabled) {
+    state = state.copyWith(useCustomSpotifyCredentials: enabled);
+    _saveSettings();
+    _applySpotifyCredentials();
+  }
+
+  void setMetadataSource(String source) {
+    state = state.copyWith(metadataSource: source);
+    _saveSettings();
+  }
+
+  void setSearchProvider(String? provider) {
+    state = state.copyWith(searchProvider: provider);
+    _saveSettings();
+  }
+
+  void setEnableLogging(bool enabled) {
+    state = state.copyWith(enableLogging: enabled);
+    _saveSettings();
+    // Sync logging state to LogBuffer
+    LogBuffer.loggingEnabled = enabled;
+  }
+
+  void setUseExtensionProviders(bool enabled) {
+    state = state.copyWith(useExtensionProviders: enabled);
+    _saveSettings();
+  }
 }
 
 final settingsProvider = NotifierProvider<SettingsNotifier, AppSettings>(

lib/providers/theme_provider.dart

@@ -24,11 +24,13 @@ class ThemeNotifier extends Notifier<ThemeSettings> {
       final modeString = prefs.getString(kThemeModeKey);
       final useDynamic = prefs.getBool(kUseDynamicColorKey);
       final seedColor = prefs.getInt(kSeedColorKey);
+      final useAmoled = prefs.getBool(kUseAmoledKey);
 
       state = ThemeSettings(
         themeMode: _themeModeFromString(modeString),
         useDynamicColor: useDynamic ?? true,
         seedColorValue: seedColor ?? kDefaultSeedColor,
+        useAmoled: useAmoled ?? false,
       );
     } catch (e) {
       debugPrint('Error loading theme settings: $e');
@@ -43,6 +45,7 @@ class ThemeNotifier extends Notifier<ThemeSettings> {
       await prefs.setString(kThemeModeKey, state.themeMode.name);
       await prefs.setBool(kUseDynamicColorKey, state.useDynamicColor);
       await prefs.setInt(kSeedColorKey, state.seedColorValue);
+      await prefs.setBool(kUseAmoledKey, state.useAmoled);
     } catch (e) {
       debugPrint('Error saving theme settings: $e');
     }
@@ -72,6 +75,12 @@ class ThemeNotifier extends Notifier<ThemeSettings> {
     await _saveToStorage();
   }
 
+  /// Enable or disable AMOLED mode (pure black background)
+  Future<void> setUseAmoled(bool value) async {
+    state = state.copyWith(useAmoled: value);
+    await _saveToStorage();
+  }
+
   /// Helper to convert string to ThemeMode
   ThemeMode _themeModeFromString(String? value) {
     if (value == null) return ThemeMode.system;