优化部分功能逻辑：元数据信息漂移

优化部分体验问题，包含动画、界面层级等

lib/services/audio_service.dart

@@ -3,6 +3,7 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:typed_data';
 import 'package:flutter/material.dart';
+import 'package:media_kit/media_kit.dart';
 import 'package:path_provider/path_provider.dart';
 import 'playback_service.dart';
 import '../metadata/metadata_service.dart';
@@ -60,6 +61,9 @@ class AudioService extends ChangeNotifier {
 
   bool _isUserSeeking = false;
 
+  // ⭐ 播放代数：每次切歌递增，用于校验异步任务是否过期
+  int _playbackGeneration = 0;
+
   // ---- Getter ----
   Song? get currentSong => _currentSong;
   bool get isPlaying => _isPlaying;
@@ -144,6 +148,9 @@ class AudioService extends ChangeNotifier {
       return;
     }
 
+    _playbackGeneration++;
+    final generation = _playbackGeneration;
+
     final song = _queue[_currentIndex];
     _currentSong = song;
 
@@ -158,7 +165,11 @@ class AudioService extends ChangeNotifier {
 
     _syncPlayerStateDelayed();
 
-    _loadMetadataForCurrentSong();
+    // ⭐ 立即推送基本信息（无 artwork）
+    _onSongChanged?.call(song);
+
+    // ⭐ 异步加载完整 metadata（含 artwork）
+    _loadMetadataForCurrentSong(generation);
   }
 
   String _generateSongKey(String url, int fileSize, int modifiedTime) {
@@ -166,10 +177,21 @@ class AudioService extends ChangeNotifier {
     return raw.hashCode.toString();
   }
 
-  Future<void> _loadMetadataForCurrentSong() async {
+  // ⭐ 核心：带 generation 校验的 metadata 加载
+  // lib/services/audio_service.dart
+
+  Future<void> _loadMetadataForCurrentSong(int generation) async {
     if (_currentIndex < 0 || _currentIndex >= _queue.length) return;
-    final song = _queue[_currentIndex];
-    if (song.url == null || song.url!.isEmpty) return;
+
+    final currentIndex = _currentIndex;
+    final song = _queue[currentIndex];
+    final songId = song.id;
+
+    if (song.url == null || song.url!.isEmpty) {
+      // 没有 URL，直接推送 fallback
+      _onSongChanged?.call(song);
+      return;
+    }
 
     try {
       final metadata = await MetadataService().getMetadata(
@@ -178,23 +200,41 @@ class AudioService extends ChangeNotifier {
         fileId: song.id,
       );
 
-      if (metadata.isNotEmpty) {
-        final updatedSong = Song(
-          id: song.id,
-          title: metadata.title.isNotEmpty ? metadata.title : song.title,
-          artist: metadata.artist.isNotEmpty ? metadata.artist : song.artist,
-          url: song.url,
-          artwork: metadata.artwork, // ✅ 已有
-        );
-        _queue[_currentIndex] = updatedSong;
-        _currentSong = updatedSong;
-        notifyListeners();
-
-        // ⭐ 传递完整的 updatedSong（包含 artwork）
-        _onSongChanged?.call(updatedSong);
+      // generation 校验
+      if (_playbackGeneration != generation) {
+        debugPrint('⚠️ [AudioService] metadata stale (generation), ignoring');
+        return;
       }
+      if (_currentIndex != currentIndex) {
+        debugPrint(
+            '⚠️ [AudioService] metadata stale (index changed), ignoring');
+        return;
+      }
+      if (currentIndex >= _queue.length || _queue[currentIndex].id != songId) {
+        debugPrint('⚠️ [AudioService] metadata stale (song changed), ignoring');
+        return;
+      }
+
+      // 更新 Song
+      final updatedSong = Song(
+        id: song.id,
+        title: metadata.title.isNotEmpty ? metadata.title : song.title,
+        artist: metadata.artist.isNotEmpty ? metadata.artist : song.artist,
+        url: song.url,
+        artwork: metadata.artwork,
+      );
+      _queue[_currentIndex] = updatedSong;
+      _currentSong = updatedSong;
+      notifyListeners();
+
+      // ⭐ 一次性推送完整数据（含 artwork）
+      _onSongChanged?.call(updatedSong);
+      debugPrint(
+          '✅ [AudioService] metadata updated: ${updatedSong.title} - ${updatedSong.artist} (generation $generation)');
     } catch (e) {
-      debugPrint('⚠️ [AudioService] metadata load failed: $e');
+      debugPrint('⚠️ [AudioService] metadata load failed: $e, using fallback');
+      // 异常时推送 fallback（无 artwork）
+      _onSongChanged?.call(song);
     }
   }
 
@@ -207,10 +247,8 @@ class AudioService extends ChangeNotifier {
 
     debugPrint('🗑️ [AudioService] clearing cache for: ${song.title}');
 
-    // 1. 获取当前索引
     final currentIndex = _currentIndex;
 
-    // 2. 尝试获取文件信息生成 song_key
     String songKey;
     try {
       final provider = MetadataService().getProviderForUrl(url);
@@ -226,17 +264,14 @@ class AudioService extends ChangeNotifier {
       songKey = url.hashCode.toString();
     }
 
-    // 3. 清除 SQLite 记录
     final db = SongDatabase();
     await db.deleteSong(songKey);
     await db.deleteCache(songKey);
     debugPrint('🗑️ [AudioService] SQLite records deleted: $songKey');
 
-    // 4. 删除封面图
     await ArtworkHelper.deleteArtwork(songKey);
     debugPrint('🗑️ [AudioService] artwork deleted');
 
-    // 5. 删除 metadata 临时缓存文件
     try {
       final cacheDir = await getTemporaryDirectory();
       final cachePath = '${cacheDir.path}/metadata_${url.hashCode}.tmp';
@@ -249,14 +284,11 @@ class AudioService extends ChangeNotifier {
       // 忽略
     }
 
-    // 6. 清除内存缓存
     await MetadataService().clearCache(song.id);
     debugPrint('🗑️ [AudioService] memory cache cleared');
 
-    // 7. 停止并重新播放
     if (currentIndex >= 0 && currentIndex < _queue.length) {
       stopPlay();
-      // 确保重新播放同一首歌
       _playCurrent();
       debugPrint('🔄 [AudioService] song reloaded');
     }