snapshot: 存档 flutter create 模板覆盖后的现场，作为多实例修复前的基线

lib/services/playback_service.dart

@@ -1,20 +1,24 @@
 // lib/services/playback_service.dart
 import 'package:media_kit/media_kit.dart';
+import 'package:flutter/foundation.dart';
 
-// ============================================================
-// PlaybackService - 播放引擎封装
-// 职责：管理 Player 生命周期，不涉及业务逻辑
-// ============================================================
 class PlaybackService {
   static final PlaybackService _instance = PlaybackService._internal();
   factory PlaybackService() => _instance;
-  PlaybackService._internal();
+  PlaybackService._internal() {
+    // ⭐ 给单例本身打上 ID
+    _serviceId = DateTime.now().microsecondsSinceEpoch.toString();
+    debugPrint('🎯 [PlaybackService] 单例创建, serviceId=$_serviceId');
+  }
 
   Player? _player;
   bool _initialized = false;
+  late final String _serviceId; // ⭐ 服务实例 ID
 
   // ---------- Getter ----------
   Player get player {
+    debugPrint(
+        '🎯 [PlaybackService] get player called, serviceId=$_serviceId, initialized=$_initialized, player=${_player?.hashCode}');
     if (!_initialized) init();
     return _player!;
   }
@@ -23,16 +27,21 @@ class PlaybackService {
 
   // ---------- 初始化 ----------
   void init() {
-    if (_initialized) return;
+    if (_initialized) {
+      debugPrint(
+          '⚠️ [PlaybackService] init() 被重复调用, 跳过, serviceId=$_serviceId, player=${_player?.hashCode}');
+      return;
+    }
     _player = Player();
     _initialized = true;
-
-    // 可以在这里配置初始参数
-    // _player.setVolume(1.0);
+    debugPrint(
+        '✅ [PlaybackService] Player 已创建, serviceId=$_serviceId, player=${_player.hashCode}');
   }
 
   // ---------- 播放 ----------
   Future<void> play(String url, {Map<String, String>? headers}) async {
+    debugPrint(
+        '▶️ [PlaybackService] play() called, serviceId=$_serviceId, player=${_player?.hashCode}');
     if (!_initialized) init();
 
     final media = (headers != null && headers.isNotEmpty)
@@ -45,24 +54,32 @@ class PlaybackService {
 
   // ---------- 控制 ----------
   Future<void> pause() async {
+    debugPrint(
+        '⏸️ [PlaybackService] pause() called, serviceId=$_serviceId, player=${_player?.hashCode}');
     if (_initialized && _player != null) {
       await _player!.pause();
     }
   }
 
   Future<void> resume() async {
+    debugPrint(
+        '▶️ [PlaybackService] resume() called, serviceId=$_serviceId, player=${_player?.hashCode}');
     if (_initialized && _player != null) {
       await _player!.play();
     }
   }
 
   Future<void> stop() async {
+    debugPrint(
+        '⏹️ [PlaybackService] stop() called, serviceId=$_serviceId, player=${_player?.hashCode}');
     if (_initialized && _player != null) {
       await _player!.stop();
     }
   }
 
   Future<void> seek(Duration position) async {
+    debugPrint(
+        '⏩ [PlaybackService] seek() called, serviceId=$_serviceId, player=${_player?.hashCode}');
     if (_initialized && _player != null) {
       await _player!.seek(position);
     }
@@ -76,6 +93,8 @@ class PlaybackService {
 
   // ---------- 释放 ----------
   void dispose() {
+    debugPrint(
+        '🗑️ [PlaybackService] dispose() called, serviceId=$_serviceId, player=${_player?.hashCode}');
     if (_initialized && _player != null) {
       _player!.dispose();
       _player = null;
@@ -83,8 +102,10 @@ class PlaybackService {
     }
   }
 
-  // ---------- 重新初始化（用于 Hot Restart 场景） ----------
+  // ---------- 重新初始化 ----------
   void reinitialize() {
+    debugPrint(
+        '🔄 [PlaybackService] reinitialize() called, serviceId=$_serviceId');
     dispose();
     init();
   }