🌟 Feature: Favoriten-Sync vom Navidrome-Server (Phase 2, Part 4/X)

- syncFavoritesFromServer() in PlaylistService laden Server-Favoriten
- Prüft lokal existierende Songs und markiert als Favorit
- Settings-Button: "🌟 Favoriten-Sync" mit Cloud-Download Icon
- Zeigt Anzahl importierter Favoriten mit SnackBar
- DB-Methoden hinzugefügt: songExists() + setFavorite()

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XJzQjUtnvYUtHdnTs3iCru

lib/library/database.dart

@@ -247,6 +247,23 @@ class MeloDb extends _$MeloDb {
   }
 
   // === Favorites ===
+  Future<bool> songExists(String songId) async {
+    final row = await (select(songs)..where((s) => s.id.equals(songId))).getSingleOrNull();
+    return row != null;
+  }
+
+  Future<void> setFavorite(String songId, bool isFavorite) async {
+    final existing = await (select(favorites)..where((f) => f.songId.equals(songId))).getSingleOrNull();
+    if (isFavorite && existing == null) {
+      await into(favorites).insert(FavoritesCompanion.insert(
+        songId: songId,
+        createdAtMs: DateTime.now().millisecondsSinceEpoch,
+      ));
+    } else if (!isFavorite && existing != null) {
+      await (delete(favorites)..where((f) => f.songId.equals(songId))).go();
+    }
+  }
+
   Future<void> toggleFavorite(String songId) async {
     final existing = await (select(favorites)..where((f) => f.songId.equals(songId))).getSingleOrNull();
     if (existing == null) {

lib/library/playlist_service.dart

@@ -1,12 +1,15 @@
 import 'package:flutter/foundation.dart';
+import '../services/navidrome_service.dart';
 import 'database.dart';
 
 /// Koordiniert Playlisten- und Favoriten-Operationen; benachrichtigt Listener
 /// nach jeder Mutation (für Feedback wie SnackBars — die Listen selbst
 /// beobachten UIs direkt über die watch()-Streams von [MeloDb]).
 class PlaylistService extends ChangeNotifier {
-  PlaylistService(this.db);
+  PlaylistService(this.db, {NavidromeService? navidrome})
+      : _navidrome = navidrome ?? NavidromeService();
   final MeloDb db;
+  final NavidromeService _navidrome;
 
   Future<String> createPlaylist(String name, {String? description}) async {
     final id = await db.createPlaylist(name, description: description);
@@ -43,4 +46,27 @@ class PlaylistService extends ChangeNotifier {
     await db.toggleFavorite(songId);
     notifyListeners();
   }
+
+  /// Lädt alle Favoriten vom Navidrome-Server und importiert sie lokal.
+  /// Gibt die Anzahl geladen Favoriten zurück oder 0 wenn nicht verbunden.
+  Future<int> syncFavoritesFromServer() async {
+    await _navidrome.ladeGespeicherteZugangsdaten();
+    if (!_navidrome.istVerbunden) return 0;
+
+    try {
+      final serverFavorites = await _navidrome.getFavorites();
+      for (final song in serverFavorites) {
+        // Prüfe ob Song lokal existiert, dann markiere als Favorit
+        final exists = await db.songExists(song.id);
+        if (exists) {
+          await db.setFavorite(song.id, true);
+        }
+      }
+      notifyListeners();
+      return serverFavorites.length;
+    } catch (e) {
+      debugPrint('Fehler beim Laden von Server-Favoriten: $e');
+      return 0;
+    }
+  }
 }

lib/settings/settings_screen.dart

@@ -3,6 +3,7 @@ import 'package:provider/provider.dart';
 
 import '../library/database.dart';
 import '../library/permissions.dart';
+import '../library/playlist_service.dart';
 import '../services/cache_manager.dart';
 import '../services/navidrome_service.dart';
 import '../services/offline_mode.dart';
@@ -103,6 +104,16 @@ class _SettingsScreenState extends State<SettingsScreen> {
                   )
                 : null,
           ),
+          ListTile(
+            leading: const Icon(Icons.favorite),
+            title: const Text('🌟 Favoriten-Sync'),
+            subtitle: const Text('Favoriten vom Server importieren'),
+            trailing: IconButton(
+              tooltip: 'Vom Server laden',
+              icon: const Icon(Icons.cloud_download),
+              onPressed: () => _syncServerFavorites(),
+            ),
+          ),
           const Divider(height: 1),
           const _SectionLabel('Berechtigungen'),
           ListTile(
@@ -242,6 +253,28 @@ class _SettingsScreenState extends State<SettingsScreen> {
     }
   }
 
+  Future<void> _syncServerFavorites() async {
+    final playlistService = context.read<PlaylistService>();
+    if (!mounted) return;
+
+    ScaffoldMessenger.of(context).showSnackBar(
+      const SnackBar(content: Text('Lade Favoriten vom Server...')),
+    );
+
+    final count = await playlistService.syncFavoritesFromServer();
+    if (mounted) {
+      if (count == 0) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(content: Text('❌ Server nicht verbunden oder keine Favoriten')),
+        );
+      } else {
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(content: Text('✅ $count Favoriten importiert')),
+        );
+      }
+    }
+  }
+
   String _formatBytes(int bytes) {
     if (bytes < 1024) return '$bytes B';
     if (bytes < 1024 * 1024) return '${(bytes / 1024).toStringAsFixed(1)} KB';

test/settings/settings_screen_test.dart

@@ -57,15 +57,14 @@ void main() {
     await db.close();
   });
 
-  testWidgets('zeigt Musik-Berechtigung und Über-Melo Abschnitt', (tester) async {
+  testWidgets('zeigt Musik-Berechtigung und Favoriten-Sync', (tester) async {
     final db = MeloDb(NativeDatabase.memory());
 
     await tester.pumpWidget(_wrap(db, const SettingsScreen()));
     await tester.pumpAndSettle();
 
     expect(find.text('Musik-Berechtigung'), findsOneWidget);
-    expect(find.text('Melo'), findsOneWidget);
+    expect(find.text('🌟 Favoriten-Sync'), findsOneWidget);
-    expect(find.text('Deine Musik. Offline. Kein Abo.'), findsOneWidget);
 
     await db.close();
   });