feat: add built-in Tidal/Qobuz search with recommended service picker

- Add SearchAll() for Tidal and Qobuz in Go backend (tracks, artists, albums)
- Add searchTidalAll/searchQobuzAll platform routing for Android and iOS
- Add Tidal/Qobuz options to search provider dropdown in home tab
- Show (Recommended) label and auto-select service in download picker

lib/providers/download_queue_provider.dart

@@ -3642,6 +3642,15 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
                 e.hasDownloadProvider &&
                 e.id.toLowerCase() == item.service.toLowerCase(),
           );
+      final trackSource = (trackToDownload.source ?? '').trim().toLowerCase();
+      final shouldSkipExtensionSongLinkPrelookup =
+          trackSource.isNotEmpty &&
+          extensionState.extensions.any(
+            (e) =>
+                e.enabled &&
+                e.hasMetadataProvider &&
+                e.id.toLowerCase() == trackSource,
+          );
 
       String? deezerTrackId = trackToDownload.deezerId;
       if (deezerTrackId == null && trackToDownload.id.startsWith('deezer:')) {
@@ -3678,6 +3687,7 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
       // Fallback: Use SongLink to convert Spotify ID to Deezer ID
       if (!selectedExtensionDownloadProvider &&
           deezerTrackId == null &&
+          !shouldSkipExtensionSongLinkPrelookup &&
           trackToDownload.id.isNotEmpty &&
           !trackToDownload.id.startsWith('deezer:') &&
           !trackToDownload.id.startsWith('extension:')) {
@@ -3782,6 +3792,11 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
         _log.d(
           'Skipping Flutter SongLink Deezer prelookup for extension provider: ${item.service}',
         );
+      } else if (shouldSkipExtensionSongLinkPrelookup &&
+          deezerTrackId == null) {
+        _log.d(
+          'Skipping Flutter SongLink Deezer prelookup for extension-sourced track; backend metadata enrichment will resolve identifiers first',
+        );
       }
 
       if (deezerTrackId != null && deezerTrackId.isNotEmpty) {
@@ -4179,8 +4194,9 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
                     progress: 0.95,
                   );
 
-                  final format =
-                      tidalHighFormat.startsWith('opus') ? 'opus' : 'mp3';
+                  final format = tidalHighFormat.startsWith('opus')
+                      ? 'opus'
+                      : 'mp3';
                   convertedPath = await FFmpegService.convertM4aToLossy(
                     tempPath,
                     format: format,
@@ -4359,8 +4375,9 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
                   progress: 0.95,
                 );
 
-                final format =
-                    tidalHighFormat.startsWith('opus') ? 'opus' : 'mp3';
+                final format = tidalHighFormat.startsWith('opus')
+                    ? 'opus'
+                    : 'mp3';
                 final convertedPath = await FFmpegService.convertM4aToLossy(
                   currentFilePath,
                   format: format,

lib/providers/extension_provider.dart

@@ -504,6 +504,11 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
   }
 
   Future<void> _cleanupExtensions({required String reason}) async {
+    if (!PlatformBridge.supportsExtensionSystem) {
+      _cleanupInFlight = false;
+      return;
+    }
+
     try {
       await PlatformBridge.cleanupExtensions();
       _log.d('Extensions cleaned up ($reason)');
@@ -519,6 +524,17 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
 
     state = state.copyWith(isLoading: true, error: null);
 
+    if (!PlatformBridge.supportsExtensionSystem) {
+      state = state.copyWith(
+        isInitialized: true,
+        isLoading: false,
+        extensions: const [],
+        error: null,
+      );
+      _log.i('Extension system disabled on this platform');
+      return;
+    }
+
     try {
       await PlatformBridge.initExtensionSystem(extensionsDir, dataDir);
       await loadExtensions(extensionsDir);

lib/providers/settings_provider.dart

@@ -53,6 +53,8 @@ class SettingsNotifier extends Notifier<AppSettings> {
   }
 
   void _syncLyricsSettingsToBackend() {
+    if (!PlatformBridge.supportsCoreBackend) return;
+
     PlatformBridge.setLyricsProviders(state.lyricsProviders).catchError((e) {
       _log.w('Failed to sync lyrics providers to backend: $e');
     });
@@ -68,6 +70,8 @@ class SettingsNotifier extends Notifier<AppSettings> {
   }
 
   void _syncNetworkCompatibilitySettingsToBackend() {
+    if (!PlatformBridge.supportsCoreBackend) return;
+
     final compatibilityMode = state.networkCompatibilityMode;
     PlatformBridge.setNetworkCompatibilityOptions(
       allowHttp: compatibilityMode,

lib/providers/track_provider.dart

@@ -30,6 +30,8 @@ class TrackState {
   searchExtensionId; // Extension ID used for current search results
   final String?
   selectedSearchFilter; // Currently selected search filter (e.g., "track", "album", "artist", "playlist")
+  final String?
+  searchSource; // Built-in search provider used for current results (e.g., "deezer", "tidal", "qobuz")
 
   const TrackState({
     this.tracks = const [],
@@ -52,6 +54,7 @@ class TrackState {
     this.isShowingRecentAccess = false,
     this.searchExtensionId,
     this.selectedSearchFilter,
+    this.searchSource,
   });
 
   bool get hasContent =>
@@ -83,6 +86,8 @@ class TrackState {
     String? searchExtensionId,
     String? selectedSearchFilter,
     bool clearSelectedSearchFilter = false,
+    String? searchSource,
+    bool clearSearchSource = false,
   }) {
     return TrackState(
       tracks: tracks ?? this.tracks,
@@ -108,6 +113,9 @@ class TrackState {
       selectedSearchFilter: clearSelectedSearchFilter
           ? null
           : (selectedSearchFilter ?? this.selectedSearchFilter),
+      searchSource: clearSearchSource
+          ? null
+          : (searchSource ?? this.searchSource),
     );
   }
 }
@@ -618,7 +626,11 @@ class TrackNotifier extends Notifier<TrackState> {
     }
   }
 
-  Future<void> search(String query, {String? filterOverride}) async {
+  Future<void> search(
+    String query, {
+    String? filterOverride,
+    String? builtInSearchProvider,
+  }) async {
     final requestId = ++_currentRequestId;
 
     // Preserve selected filter during loading
@@ -640,39 +652,68 @@ class TrackNotifier extends Notifier<TrackState> {
       final includeExtensions =
           settings.useExtensionProviders && hasActiveMetadataExtensions;
 
+      // Determine the effective search provider
+      final effectiveProvider = builtInSearchProvider ?? 'deezer';
+
       _log.i(
-        'Search started: metadataProviders, query="$query", includeExtensions=$includeExtensions, filter=$currentFilter',
+        'Search started: provider=$effectiveProvider, query="$query", includeExtensions=$includeExtensions, filter=$currentFilter',
       );
 
       Map<String, dynamic> results;
       List<Map<String, dynamic>> metadataTrackResults = [];
 
-      try {
-        _log.d('Calling metadata provider search API...');
-        metadataTrackResults =
-            await PlatformBridge.searchTracksWithMetadataProviders(
-              query,
-              limit: 20,
-              includeExtensions: includeExtensions,
-            );
-        _log.i(
-          'Metadata providers returned ${metadataTrackResults.length} tracks',
-        );
-      } catch (e) {
-        _log.w(
-          'Metadata provider search failed, falling back to Deezer tracks: $e',
-        );
+      // Only use metadata providers for Deezer search (default behavior)
+      if (effectiveProvider == 'deezer') {
+        try {
+          _log.d('Calling metadata provider search API...');
+          metadataTrackResults =
+              await PlatformBridge.searchTracksWithMetadataProviders(
+                query,
+                limit: 20,
+                includeExtensions: includeExtensions,
+              );
+          _log.i(
+            'Metadata providers returned ${metadataTrackResults.length} tracks',
+          );
+        } catch (e) {
+          _log.w(
+            'Metadata provider search failed, falling back to Deezer tracks: $e',
+          );
+        }
       }
 
-      _log.d('Calling Deezer search API...');
-      results = await PlatformBridge.searchDeezerAll(
-        query,
-        trackLimit: 20,
-        artistLimit: 2,
-        filter: currentFilter,
-      );
+      // Call the appropriate search API
+      switch (effectiveProvider) {
+        case 'tidal':
+          _log.d('Calling Tidal search API...');
+          results = await PlatformBridge.searchTidalAll(
+            query,
+            trackLimit: 20,
+            artistLimit: 2,
+            filter: currentFilter,
+          );
+          break;
+        case 'qobuz':
+          _log.d('Calling Qobuz search API...');
+          results = await PlatformBridge.searchQobuzAll(
+            query,
+            trackLimit: 20,
+            artistLimit: 2,
+            filter: currentFilter,
+          );
+          break;
+        default:
+          _log.d('Calling Deezer search API...');
+          results = await PlatformBridge.searchDeezerAll(
+            query,
+            trackLimit: 20,
+            artistLimit: 2,
+            filter: currentFilter,
+          );
+          break;
+      }
       _log.i(
-        'Deezer returned ${(results['tracks'] as List?)?.length ?? 0} tracks, ${(results['artists'] as List?)?.length ?? 0} artists, ${(results['albums'] as List?)?.length ?? 0} albums',
+        '$effectiveProvider returned ${(results['tracks'] as List?)?.length ?? 0} tracks, ${(results['artists'] as List?)?.length ?? 0} artists, ${(results['albums'] as List?)?.length ?? 0} albums',
       );
 
       if (!_isRequestValid(requestId)) {
@@ -758,6 +799,8 @@ class TrackNotifier extends Notifier<TrackState> {
         hasSearchText: state.hasSearchText,
         isShowingRecentAccess: state.isShowingRecentAccess,
         selectedSearchFilter: currentFilter, // Preserve filter in results
+        searchSource:
+            effectiveProvider, // Track which service was used for search
       );
     } catch (e, stackTrace) {
       if (!_isRequestValid(requestId)) return;