feat: export failed downloads to TXT file

- Add Export button in queue when there are failed downloads
- Add auto-export setting in Download Settings
- Export includes track name, artist, Spotify/Deezer URL, and error message
- Clear Failed action in snackbar after export

CHANGELOG.md

@@ -4,6 +4,11 @@
 
 Same as 3.3.1 but fixes crash issues caused by FFmpeg.
 
+### Added
+
+- **Export Failed Downloads**: Export failed downloads to TXT file for easy lookup on other platforms
+- **Auto-Export Setting**: Option to automatically export failed downloads when queue finishes
+
 ### Fixed
 
 - **FFmpeg Crash**: Fixed crash issues during M4A to MP3/Opus conversion

lib/l10n/app_localizations.dart

@@ -3652,6 +3652,42 @@ abstract class AppLocalizations {
   /// **'Are you sure you want to clear all downloads?'**
   String get queueClearAllMessage;
 
+  /// Button - export failed downloads to TXT
+  ///
+  /// In en, this message translates to:
+  /// **'Export'**
+  String get queueExportFailed;
+
+  /// Success message after exporting failed downloads
+  ///
+  /// In en, this message translates to:
+  /// **'Failed downloads exported to TXT file'**
+  String get queueExportFailedSuccess;
+
+  /// Action to clear failed downloads after export
+  ///
+  /// In en, this message translates to:
+  /// **'Clear Failed'**
+  String get queueExportFailedClear;
+
+  /// Error message when export fails
+  ///
+  /// In en, this message translates to:
+  /// **'Failed to export downloads'**
+  String get queueExportFailedError;
+
+  /// Setting toggle for auto-export
+  ///
+  /// In en, this message translates to:
+  /// **'Auto-export failed downloads'**
+  String get settingsAutoExportFailed;
+
+  /// Subtitle for auto-export setting
+  ///
+  /// In en, this message translates to:
+  /// **'Save failed downloads to TXT file automatically'**
+  String get settingsAutoExportFailedSubtitle;
+
   /// Empty queue state title
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_de.dart

@@ -2005,6 +2005,26 @@ class AppLocalizationsDe extends AppLocalizations {
   String get queueClearAllMessage =>
       'Are you sure you want to clear all downloads?';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'No downloads in queue';
 

lib/l10n/app_localizations_en.dart

@@ -1990,6 +1990,26 @@ class AppLocalizationsEn extends AppLocalizations {
   String get queueClearAllMessage =>
       'Are you sure you want to clear all downloads?';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'No downloads in queue';
 

lib/l10n/app_localizations_es.dart

@@ -1990,6 +1990,26 @@ class AppLocalizationsEs extends AppLocalizations {
   String get queueClearAllMessage =>
       'Are you sure you want to clear all downloads?';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'No downloads in queue';
 

lib/l10n/app_localizations_fr.dart

@@ -1990,6 +1990,26 @@ class AppLocalizationsFr extends AppLocalizations {
   String get queueClearAllMessage =>
       'Are you sure you want to clear all downloads?';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'No downloads in queue';
 

lib/l10n/app_localizations_hi.dart

@@ -1990,6 +1990,26 @@ class AppLocalizationsHi extends AppLocalizations {
   String get queueClearAllMessage =>
       'Are you sure you want to clear all downloads?';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'No downloads in queue';
 

lib/l10n/app_localizations_id.dart

@@ -2003,6 +2003,26 @@ class AppLocalizationsId extends AppLocalizations {
   String get queueClearAllMessage =>
       'Apakah Anda yakin ingin menghapus semua unduhan?';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'Tidak ada unduhan dalam antrian';
 

lib/l10n/app_localizations_ja.dart

@@ -1977,6 +1977,26 @@ class AppLocalizationsJa extends AppLocalizations {
   @override
   String get queueClearAllMessage => 'すべてのダウンロードを消去してもよろしいですか？';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'キューにダウンロードがありません';
 

lib/l10n/app_localizations_ko.dart

@@ -1990,6 +1990,26 @@ class AppLocalizationsKo extends AppLocalizations {
   String get queueClearAllMessage =>
       'Are you sure you want to clear all downloads?';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'No downloads in queue';
 

lib/l10n/app_localizations_nl.dart

@@ -1990,6 +1990,26 @@ class AppLocalizationsNl extends AppLocalizations {
   String get queueClearAllMessage =>
       'Are you sure you want to clear all downloads?';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'No downloads in queue';
 

lib/l10n/app_localizations_pt.dart

@@ -1990,6 +1990,26 @@ class AppLocalizationsPt extends AppLocalizations {
   String get queueClearAllMessage =>
       'Are you sure you want to clear all downloads?';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'No downloads in queue';
 

lib/l10n/app_localizations_ru.dart

@@ -2029,6 +2029,26 @@ class AppLocalizationsRu extends AppLocalizations {
   String get queueClearAllMessage =>
       'Вы уверены, что хотите очистить все загрузки?';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'Нет загрузок в очереди';
 

lib/l10n/app_localizations_tr.dart

@@ -2005,6 +2005,26 @@ class AppLocalizationsTr extends AppLocalizations {
   String get queueClearAllMessage =>
       'Are you sure you want to clear all downloads?';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'No downloads in queue';
 

lib/l10n/app_localizations_zh.dart

@@ -1990,6 +1990,26 @@ class AppLocalizationsZh extends AppLocalizations {
   String get queueClearAllMessage =>
       'Are you sure you want to clear all downloads?';
 
+  @override
+  String get queueExportFailed => 'Export';
+
+  @override
+  String get queueExportFailedSuccess =>
+      'Failed downloads exported to TXT file';
+
+  @override
+  String get queueExportFailedClear => 'Clear Failed';
+
+  @override
+  String get queueExportFailedError => 'Failed to export downloads';
+
+  @override
+  String get settingsAutoExportFailed => 'Auto-export failed downloads';
+
+  @override
+  String get settingsAutoExportFailedSubtitle =>
+      'Save failed downloads to TXT file automatically';
+
   @override
   String get queueEmpty => 'No downloads in queue';
 

lib/l10n/arb/app_en.arb

@@ -1460,10 +1460,22 @@
 
   "queueTitle": "Download Queue",
   "@queueTitle": {"description": "Queue screen title"},
-  "queueClearAll": "Clear All",
+"queueClearAll": "Clear All",
   "@queueClearAll": {"description": "Button - clear all queue items"},
   "queueClearAllMessage": "Are you sure you want to clear all downloads?",
   "@queueClearAllMessage": {"description": "Clear queue confirmation"},
+  "queueExportFailed": "Export",
+  "@queueExportFailed": {"description": "Button - export failed downloads to TXT"},
+  "queueExportFailedSuccess": "Failed downloads exported to TXT file",
+  "@queueExportFailedSuccess": {"description": "Success message after exporting failed downloads"},
+  "queueExportFailedClear": "Clear Failed",
+  "@queueExportFailedClear": {"description": "Action to clear failed downloads after export"},
+  "queueExportFailedError": "Failed to export downloads",
+  "@queueExportFailedError": {"description": "Error message when export fails"},
+  "settingsAutoExportFailed": "Auto-export failed downloads",
+  "@settingsAutoExportFailed": {"description": "Setting toggle for auto-export"},
+  "settingsAutoExportFailedSubtitle": "Save failed downloads to TXT file automatically",
+  "@settingsAutoExportFailedSubtitle": {"description": "Subtitle for auto-export setting"},
   "queueEmpty": "No downloads in queue",
   "@queueEmpty": {"description": "Empty queue state title"},
   "queueEmptySubtitle": "Add tracks from the home screen",

lib/models/settings.dart

@@ -34,6 +34,7 @@ class AppSettings {
   final String lyricsMode;
   final String tidalHighFormat; // Format for Tidal HIGH quality: 'mp3_320' or 'opus_128'
   final bool useAllFilesAccess; // Android 13+ only: enable MANAGE_EXTERNAL_STORAGE
+  final bool autoExportFailedDownloads; // Auto export failed downloads to TXT file
 
   const AppSettings({
     this.defaultService = 'tidal',
@@ -66,6 +67,7 @@ class AppSettings {
     this.lyricsMode = 'embed',
     this.tidalHighFormat = 'mp3_320',
     this.useAllFilesAccess = false,
+    this.autoExportFailedDownloads = false,
   });
 
   AppSettings copyWith({
@@ -100,6 +102,7 @@ class AppSettings {
     String? lyricsMode,
     String? tidalHighFormat,
     bool? useAllFilesAccess,
+    bool? autoExportFailedDownloads,
   }) {
     return AppSettings(
       defaultService: defaultService ?? this.defaultService,
@@ -132,6 +135,7 @@ class AppSettings {
       lyricsMode: lyricsMode ?? this.lyricsMode,
       tidalHighFormat: tidalHighFormat ?? this.tidalHighFormat,
       useAllFilesAccess: useAllFilesAccess ?? this.useAllFilesAccess,
+      autoExportFailedDownloads: autoExportFailedDownloads ?? this.autoExportFailedDownloads,
     );
   }
 

lib/models/settings.g.dart

@@ -39,6 +39,8 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
   lyricsMode: json['lyricsMode'] as String? ?? 'embed',
   tidalHighFormat: json['tidalHighFormat'] as String? ?? 'mp3_320',
   useAllFilesAccess: json['useAllFilesAccess'] as bool? ?? false,
+  autoExportFailedDownloads:
+      json['autoExportFailedDownloads'] as bool? ?? false,
 );
 
 Map<String, dynamic> _$AppSettingsToJson(AppSettings instance) =>
@@ -73,4 +75,5 @@ Map<String, dynamic> _$AppSettingsToJson(AppSettings instance) =>
       'lyricsMode': instance.lyricsMode,
       'tidalHighFormat': instance.tidalHighFormat,
       'useAllFilesAccess': instance.useAllFilesAccess,
+      'autoExportFailedDownloads': instance.autoExportFailedDownloads,
     };

lib/providers/download_queue_provider.dart

@@ -1012,12 +1012,74 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
     }
   }
 
-  void removeItem(String id) {
+void removeItem(String id) {
     final items = state.items.where((item) => item.id != id).toList();
     state = state.copyWith(items: items);
     _saveQueueToStorage();
   }
 
+  /// Export failed downloads to a TXT file
+  /// Returns the file path if successful, null otherwise
+  Future<String?> exportFailedDownloads() async {
+    final failedItems = state.items
+        .where((item) => item.status == DownloadStatus.failed)
+        .toList();
+
+    if (failedItems.isEmpty) {
+      _log.d('No failed downloads to export');
+      return null;
+    }
+
+    try {
+      final buffer = StringBuffer();
+      buffer.writeln('# SpotiFLAC Failed Downloads');
+      buffer.writeln('# Exported: ${DateTime.now().toIso8601String()}');
+      buffer.writeln('# Total: ${failedItems.length} tracks');
+      buffer.writeln('#');
+      buffer.writeln('# Format: Track - Artist | Spotify URL | Error');
+      buffer.writeln('');
+
+      for (final item in failedItems) {
+        final track = item.track;
+        final spotifyUrl = track.id.startsWith('deezer:')
+            ? 'https://www.deezer.com/track/${track.id.substring(7)}'
+            : 'https://open.spotify.com/track/${track.id}';
+        final error = item.error ?? 'Unknown error';
+        buffer.writeln('${track.name} - ${track.artistName} | $spotifyUrl | $error');
+      }
+
+      // Save to download directory
+      String exportDir = state.outputDir;
+      if (exportDir.isEmpty) {
+        final dir = await getApplicationDocumentsDirectory();
+        exportDir = dir.path;
+      }
+
+      final timestamp = DateTime.now().toIso8601String().replaceAll(':', '-').split('.').first;
+      final fileName = 'failed_downloads_$timestamp.txt';
+      final filePath = '$exportDir/$fileName';
+
+      final file = File(filePath);
+      await file.writeAsString(buffer.toString());
+
+      _log.i('Exported ${failedItems.length} failed downloads to: $filePath');
+      return filePath;
+    } catch (e) {
+      _log.e('Failed to export failed downloads: $e');
+      return null;
+    }
+  }
+
+  /// Clear all failed downloads from queue
+  void clearFailedDownloads() {
+    final items = state.items
+        .where((item) => item.status != DownloadStatus.failed)
+        .toList();
+    state = state.copyWith(items: items);
+    _saveQueueToStorage();
+    _log.d('Cleared failed downloads from queue');
+  }
+
   Future<void> _runPostProcessingHooks(String filePath, Track track) async {
     try {
       final settings = ref.read(settingsProvider);
@@ -1626,7 +1688,7 @@ if (state.outputDir.isEmpty) {
       _downloadCount = 0;
     }
 
-    _log.i(
+_log.i(
       'Queue stats - completed: $_completedInSession, failed: $_failedInSession, totalAtStart: $_totalQueuedAtStart',
     );
     if (_totalQueuedAtStart > 0) {
@@ -1634,6 +1696,15 @@ if (state.outputDir.isEmpty) {
         completedCount: _completedInSession,
         failedCount: _failedInSession,
       );
+
+      // Auto-export failed downloads if enabled
+      final settings = ref.read(settingsProvider);
+      if (settings.autoExportFailedDownloads && _failedInSession > 0) {
+        final exportPath = await exportFailedDownloads();
+        if (exportPath != null) {
+          _log.i('Auto-exported failed downloads to: $exportPath');
+        }
+      }
     }
 
     _log.i('Queue processing finished');

lib/providers/settings_provider.dart

@@ -236,10 +236,15 @@ class SettingsNotifier extends Notifier<AppSettings> {
     _saveSettings();
   }
 
-  void setUseAllFilesAccess(bool enabled) {
+void setUseAllFilesAccess(bool enabled) {
     state = state.copyWith(useAllFilesAccess: enabled);
     _saveSettings();
   }
+
+  void setAutoExportFailedDownloads(bool enabled) {
+    state = state.copyWith(autoExportFailedDownloads: enabled);
+    _saveSettings();
+  }
 }
 
 final settingsProvider = NotifierProvider<SettingsNotifier, AppSettings>(

lib/screens/queue_tab.dart

@@ -806,7 +806,9 @@ final queueItems = ref.watch(downloadQueueProvider.select((s) => s.items));
                             fontWeight: FontWeight.bold,
                           ),
                         ),
-                        const Spacer(),
+const Spacer(),
+                        _buildExportFailedButton(context, ref, colorScheme),
+                        const SizedBox(width: 4),
                         _buildPauseResumeButton(context, ref, colorScheme),
                         const SizedBox(width: 4),
                         _buildClearAllButton(context, ref, colorScheme),
@@ -1194,7 +1196,7 @@ if (queueItems.isEmpty &&
     );
   }
 
-  Widget _buildClearAllButton(
+Widget _buildClearAllButton(
     BuildContext context,
     WidgetRef ref,
     ColorScheme colorScheme,
@@ -1210,6 +1212,60 @@ if (queueItems.isEmpty &&
     );
   }
 
+  Widget _buildExportFailedButton(
+    BuildContext context,
+    WidgetRef ref,
+    ColorScheme colorScheme,
+  ) {
+    final queueState = ref.watch(downloadQueueProvider);
+    final failedCount = queueState.failedCount;
+
+    if (failedCount == 0) {
+      return const SizedBox.shrink();
+    }
+
+    return TextButton.icon(
+      onPressed: () => _exportFailedDownloads(context, ref),
+      icon: const Icon(Icons.file_download, size: 18),
+      label: Text(context.l10n.queueExportFailed),
+      style: TextButton.styleFrom(
+        visualDensity: VisualDensity.compact,
+        foregroundColor: colorScheme.tertiary,
+      ),
+    );
+  }
+
+  Future<void> _exportFailedDownloads(
+    BuildContext context,
+    WidgetRef ref,
+  ) async {
+    final filePath = await ref.read(downloadQueueProvider.notifier).exportFailedDownloads();
+    
+    if (!context.mounted) return;
+    
+    if (filePath != null) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(
+          content: Text(context.l10n.queueExportFailedSuccess),
+          action: SnackBarAction(
+            label: context.l10n.queueExportFailedClear,
+            onPressed: () {
+              ref.read(downloadQueueProvider.notifier).clearFailedDownloads();
+            },
+          ),
+          duration: const Duration(seconds: 5),
+        ),
+      );
+    } else {
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(
+          content: Text(context.l10n.queueExportFailedError),
+          backgroundColor: Theme.of(context).colorScheme.error,
+        ),
+      );
+    }
+  }
+
   Future<void> _showClearAllDialog(
     BuildContext context,
     WidgetRef ref,

lib/screens/settings/download_settings_page.dart

@@ -385,7 +385,27 @@ class _DownloadSettingsPageState extends ConsumerState<DownloadSettingsPage> {
                   ),
                 ),
               ),
-            ],
+],
+
+            const SliverToBoxAdapter(child: SizedBox(height: 16)),
+            
+            // Auto Export Failed Downloads
+            SliverToBoxAdapter(
+              child: SettingsGroup(
+                children: [
+                  SettingsSwitchItem(
+                    icon: Icons.file_download_outlined,
+                    title: context.l10n.settingsAutoExportFailed,
+                    subtitle: context.l10n.settingsAutoExportFailedSubtitle,
+                    value: settings.autoExportFailedDownloads,
+                    onChanged: (value) {
+                      ref.read(settingsProvider.notifier).setAutoExportFailedDownloads(value);
+                    },
+                    showDivider: false,
+                  ),
+                ],
+              ),
+            ),
 
             const SliverToBoxAdapter(child: SizedBox(height: 32)),
           ],