chore: clean up redundant comments across Go backend and Flutter sources

lib/models/download_item.dart

@@ -29,14 +29,14 @@ class DownloadItem {
   final DownloadStatus status;
   final double progress;
   final double speedMBps;
-  final int bytesReceived; // Bytes downloaded so far
+  final int bytesReceived;
   final int bytesTotal; // Total bytes when the server provides content length
   final String? filePath;
   final String? error;
   final DownloadErrorType? errorType;
   final DateTime createdAt;
-  final String? qualityOverride; // Override quality for this specific download
-  final String? playlistName; // Playlist context for folder organization
+  final String? qualityOverride;
+  final String? playlistName;
   final int? playlistPosition; // 1-based position in the source playlist
 
   const DownloadItem({

lib/models/settings.dart

@@ -15,11 +15,11 @@ class AppSettings {
   final String storageMode; // 'app' or 'saf'
   final String downloadTreeUri; // SAF persistable tree URI
   final bool autoFallback;
-  final bool embedMetadata; // Master switch for metadata/cover/lyrics embedding
+  final bool embedMetadata;
   final String
   artistTagMode; // 'joined' or 'split_vorbis' for Vorbis-based formats
   final bool embedLyrics;
-  final bool embedReplayGain; // Calculate and embed ReplayGain tags
+  final bool embedReplayGain;
   final bool maxQualityCover;
   final bool isFirstLaunch;
   final bool checkForUpdates;
@@ -50,7 +50,7 @@ class AppSettings {
   final bool
   useAllFilesAccess; // Android 13+ only: enable MANAGE_EXTERNAL_STORAGE
   final bool
-  autoExportFailedDownloads; // Auto export failed downloads to TXT file
+  autoExportFailedDownloads;
   final String
   downloadNetworkMode; // 'any' = WiFi + Mobile, 'wifi_only' = WiFi only
   final bool
@@ -62,20 +62,20 @@ class AppSettings {
   final bool
   nativeDownloadWorkerEnabled; // Experimental Android service-owned worker
 
-  final bool localLibraryEnabled; // Enable local library scanning
-  final String localLibraryPath; // Path to scan for audio files
+  final bool localLibraryEnabled;
+  final String localLibraryPath;
   final String
   localLibraryBookmark; // Base64-encoded iOS security-scoped bookmark
   final bool
-  localLibraryShowDuplicates; // Show indicator when searching for existing tracks
+  localLibraryShowDuplicates;
   final String
   localLibraryAutoScan; // Auto-scan mode: 'off', 'on_open', 'daily', 'weekly'
 
   final bool
-  hasCompletedTutorial; // Track if user has completed the app tutorial
+  hasCompletedTutorial;
 
   final List<String>
-  lyricsProviders; // Ordered list of enabled lyrics provider IDs
+  lyricsProviders;
   final bool
   lyricsIncludeTranslationNetease; // Append translated lyrics (Netease)
   final bool
@@ -91,8 +91,8 @@ class AppSettings {
   lastSeenVersion; // Last app version the user has acknowledged (e.g. '3.7.0')
 
   final bool
-  deduplicateDownloads; // Skip downloading tracks already present in history
-  final bool saveDownloadHistory; // Record completed downloads in local history
+  deduplicateDownloads;
+  final bool saveDownloadHistory;
 
   const AppSettings({
     this.defaultService = '',

lib/providers/download_queue_provider.dart

@@ -4539,14 +4539,13 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
         .where((item) => _albumRgKey(item.track) == key)
         .toList();
 
-    // If any item is still in-flight, the album isn't complete yet.
     final pending = albumItemsInQueue.where(
       (item) =>
           item.status == DownloadStatus.queued ||
           item.status == DownloadStatus.downloading ||
           item.status == DownloadStatus.finalizing,
     );
-    if (pending.isNotEmpty) return; // still in progress
+    if (pending.isNotEmpty) return;
 
     // If any item is failed/skipped, the user might retry it later.
     // Don't finalize album RG with partial data — wait until all album
@@ -4556,7 +4555,7 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
           item.status == DownloadStatus.failed ||
           item.status == DownloadStatus.skipped,
     );
-    if (retryable.isNotEmpty) return; // still retryable
+    if (retryable.isNotEmpty) return;
 
     // The accumulator entries represent successfully scanned tracks.  Entries
     // are only added after a successful ReplayGain scan, removed on retry or
@@ -4696,7 +4695,6 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
         }
         continue;
       }
-      // If any representative item is available, use its track.
       final representative = albumItems.first;
       _checkAndWriteAlbumReplayGain(representative.track);
     }

lib/screens/home_tab.dart

@@ -177,7 +177,6 @@ class _HomeTabState extends ConsumerState<HomeTab>
       },
     );
 
-    // Watch for new homeFeed extension being installed/enabled after init
     _homeFeedExtSub = ref.listenManual<bool>(
       extensionProvider.select(
         (s) => s.extensions.any((e) => e.enabled && e.hasHomeFeed),

lib/screens/main_shell.dart

@@ -772,7 +772,7 @@ class _SwingIconState extends State<SwingIcon>
       duration: const Duration(milliseconds: 600),
       vsync: this,
     );
-    // Create a swinging motion (like a pendulum/sign)
+
     _rotationAnimation = TweenSequence<double>([
       TweenSequenceItem(tween: Tween(begin: 0.0, end: -0.2), weight: 20),
       TweenSequenceItem(tween: Tween(begin: -0.2, end: 0.15), weight: 20),

lib/screens/setup_screen.dart

@@ -531,8 +531,8 @@ class _SetupScreenState extends ConsumerState<SetupScreen> {
   }
 
   bool _isStepCompleted(int step) {
-    if (step == 0) return true; // Welcome
-    if (step == 1) return true; // Language (always valid)
+    if (step == 0) return true;
+    if (step == 1) return true;
 
     final logicStep = step - 2;
 

lib/screens/track_metadata_edit_sheet.dart

@@ -834,7 +834,6 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
 
       if (!mounted) return;
 
-      // Fetch ISRC from Deezer track metadata if still missing
       if (needsIsrc &&
           (enriched['isrc'] ?? '').trim().isEmpty &&
           deezerId != null) {

lib/screens/track_metadata_screen.dart

@@ -2691,7 +2691,6 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
             cleanFilePath,
             tempOutput,
           );
-          // Fall back to downloading from URL if extraction failed.
           if (result['error'] != null &&
               _coverUrl != null &&
               _coverUrl!.isNotEmpty) {
@@ -2782,13 +2781,10 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
 
       Map<String, dynamic> result;
       if (_fileExists) {
-        // Prefer extracting cover from the already-downloaded file to avoid
-        // a redundant network request.
         result = await PlatformBridge.extractCoverToFile(
           cleanFilePath,
           outputPath,
         );
-        // Fall back to downloading from URL if extraction failed.
         if (result['error'] != null &&
             _coverUrl != null &&
             _coverUrl!.isNotEmpty) {
@@ -2850,7 +2846,6 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
       }
 
       if (_isSafFile) {
-        // SAF file: save to temp, then copy to SAF tree
         final tempDir = await Directory.systemTemp.createTemp('lyrics_');
         final tempOutput =
             '${tempDir.path}${Platform.pathSeparator}$baseName.lrc';
@@ -4407,7 +4402,6 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
 
       var finalOutputPaths = outputPaths;
 
-      // Embed cover art into split FLAC files using Go backend
       if (coverPath != null && finalOutputPaths != null) {
         for (final path in finalOutputPaths) {
           if (path.toLowerCase().endsWith('.flac')) {

lib/services/ffmpeg_service.dart

@@ -1338,7 +1338,6 @@ class FFmpegService {
         final tempFile = File(tempOutput);
         if (await tempFile.exists()) {
           if (returnTempPath) {
-            // Caller will handle SAF write-back and cleanup.
             onTempReady?.call(tempOutput);
             return true;
           }
@@ -3051,7 +3050,6 @@ class FFmpegService {
         case 'COMMENT':
           id3Map['comment'] = value;
           break;
-        // ReplayGain as TXXX user-defined frames
         // FFmpeg writes these as TXXX frames automatically with uppercase keys
         case 'REPLAYGAINTRACKGAIN':
           id3Map['REPLAYGAIN_TRACK_GAIN'] = value;

lib/services/platform_bridge.dart

@@ -2027,8 +2027,6 @@ class PlatformBridge {
     return const <String, dynamic>{};
   }
 
-  // MARK: - iOS Security-Scoped Bookmark
-
   /// Create a security-scoped bookmark from a filesystem path picked by
   /// FilePicker on iOS. Must be called while the picker session is still active.
   /// Returns base64-encoded bookmark data, or null on failure.

lib/theme/app_theme.dart

@@ -16,11 +16,6 @@ class AppTheme {
   // cost of the predictive-back preview animation.
   static const PageTransitionsTheme _pageTransitionsTheme = PageTransitionsTheme(
     builders: <TargetPlatform, PageTransitionsBuilder>{
-      // Android default is PredictiveBackPageTransitionsBuilder, whose
-      // _PredictiveBackGestureDetector mis-routes the back gesture to a nested
-      // Navigator (flutter#152323). For NON-gesture transitions that builder
-      // already delegates to FadeForwardsPageTransitionsBuilder, so we use it
-      // directly: identical push/pop animation, minus the buggy gesture detector.
       TargetPlatform.android: FadeForwardsPageTransitionsBuilder(),
       TargetPlatform.iOS: CupertinoPageTransitionsBuilder(),
       TargetPlatform.macOS: CupertinoPageTransitionsBuilder(),

lib/widgets/animation_utils.dart

@@ -542,7 +542,7 @@ class ArtistScreenSkeleton extends StatelessWidget {
                               borderRadius: 4,
                             ),
                             const SizedBox(height: 8),
-                            // Mimics the small "In Library" badge pill.
+
                             const SkeletonBox(
                               width: 64,
                               height: 14,

lib/widgets/app_announcement_dialog.dart

@@ -121,10 +121,6 @@ Future<void> showAppAnnouncementDialog(
   required RemoteAnnouncement announcement,
   required VoidCallback onDismiss,
 }) {
-  // barrierDismissible is false so a stray tap outside the dialog can no longer
-  // close (and silently mark-as-seen) the notice. Dismissal — and the
-  // mark-as-seen side effect in onDismiss — only happens via the explicit close
-  // button or the CTA, both of which call onDismiss themselves.
   return showDialog<void>(
     context: context,
     barrierDismissible: false,

lib/widgets/audio_analysis_widget.dart

@@ -1646,7 +1646,6 @@ class _SpectrogramView extends StatelessWidget {
               },
             ),
           ),
-          // Intensity color legend (matches the spectrogram colormap).
           Padding(
             padding: const EdgeInsets.fromLTRB(40, 0, 10, 8),
             child: Row(
@@ -1731,7 +1730,6 @@ class _SpectrogramPainter extends CustomPainter {
     );
     if (plot.width <= 0 || plot.height <= 0) return;
 
-    // Spectrogram image.
     canvas.drawImageRect(
       image,
       Rect.fromLTWH(0, 0, image.width.toDouble(), image.height.toDouble()),
@@ -1760,7 +1758,6 @@ class _SpectrogramPainter extends CustomPainter {
       }
     }
 
-    // Time axis (X): 0 at the left, duration at the right.
     if (durationSec > 0) {
       final stepSec = _niceStepSec(durationSec);
       for (double ts = 0; ts <= durationSec + 0.001; ts += stepSec) {