perf(player): 限制雪碧图与海报预缓存内存并给播放位置缓存加容量上限

雪碧图解码从 2048 降到 1024、缓存从 8 张降到 3 张，避免擦洗预览驻留十几 MB 位图；
相邻集海报预缓存改用 ResizeImage 按 360/720 宽解码，不再缓存整张原图；
播放位置缓存按写入时间淘汰，最多保留 100 条，长会话不再只增不减；
观看记录详情失败日志加 kDebugMode 保护，release 下不再逐条打堆栈。

lib/core/data/services/playback_position_cache.dart

@@ -33,10 +33,15 @@ class PlaybackPositionCache {
   PlaybackPositionCache({
     DateTime Function()? now,
     this.maxAge = _defaultMaxAge,
+    this.maxEntries = defaultMaxEntries,
   }) : _now = now ?? DateTime.now;
 
+  /// 最多保留的集数：长会话连看几十部剧也不至于让 Map 无限增长。
+  static const int defaultMaxEntries = 100;
+
   final DateTime Function() _now;
   final Duration maxAge;
+  final int maxEntries;
   final Map<String, CachedPlaybackPosition> _positions = {};
 
   /// 保存最近有效播放位置；零位置不会覆盖已有记录。
@@ -57,6 +62,24 @@ class PlaybackPositionCache {
       duration: duration,
       updatedAt: _now(),
     );
+    _evictOverflow();
+  }
+
+  /// 超出上限时按写入时间淘汰最旧的一条，避免长会话内存只增不减。
+  void _evictOverflow() {
+    while (maxEntries > 0 && _positions.length > maxEntries) {
+      String? oldestKey;
+      DateTime? oldestAt;
+      for (final entry in _positions.entries) {
+        final at = entry.value.updatedAt;
+        if (oldestAt == null || at.isBefore(oldestAt)) {
+          oldestAt = at;
+          oldestKey = entry.key;
+        }
+      }
+      if (oldestKey == null) return;
+      _positions.remove(oldestKey);
+    }
   }
 
   /// 读取同剧同集且未过期的最近位置。

lib/core/data/services/sprite_thumbnail_asset_loader.dart

@@ -8,7 +8,8 @@ import 'package:dio/dio.dart';
 
 import '../../config/app_config.dart';
 
-const int spriteThumbnailDecodeMaxDimension = 2048;
+/// 雪碧图解码上限：擦洗预览只占很小一块区域，2048 会让单张位图膨胀到 16MB。
+const int spriteThumbnailDecodeMaxDimension = 1024;
 
 /// VTT 资源拒绝访问，服务层据此清缓存并重试一次。
 class SpriteThumbnailForbiddenException implements Exception {

lib/core/data/services/watch_records_controller.dart

@@ -227,14 +227,17 @@ class WatchRecordsController extends PagedListController<WatchRecord> {
       );
       return detail;
     } catch (failure, stackTrace) {
-      debugPrint(
-        '[WatchRecordsController] detail failed dramaId=$dramaId '
-        '${failure.runtimeType}: $failure',
-      );
-      debugPrintStack(
-        stackTrace: stackTrace,
-        label: '[WatchRecordsController] detail failed dramaId=$dramaId',
-      );
+      // 弱网时详情会成批失败，release 下不需要逐条打堆栈。
+      if (kDebugMode) {
+        debugPrint(
+          '[WatchRecordsController] detail failed dramaId=$dramaId '
+          '${failure.runtimeType}: $failure',
+        );
+        debugPrintStack(
+          stackTrace: stackTrace,
+          label: '[WatchRecordsController] detail failed dramaId=$dramaId',
+        );
+      }
       if (isDisposed) return null;
       final current = _recordIndex(dramaId);
       if (current < 0) return null;

lib/pages/player/player_view.dart

@@ -61,6 +61,17 @@ const double _playerLoadingSize = 24;
 const double _playerLoadingStrokeWidth = 2;
 const double _feedRefreshTopGap = 56;
 
+/// 相邻集海报预缓存宽度：列表卡片只有百来 dp，按原图解码会占数 MB。
+const int _posterPreviewWidth = 360;
+
+/// 画中画还原封面接近全屏，保留更高分辨率但不必按原图。
+const int _posterPipWidth = 720;
+
+/// 预缓存用低分辨率 provider；与 RemoteImage 一样限制解码尺寸，避免整张原图进缓存。
+ImageProvider _posterProvider(String url, {required int width}) {
+  return ResizeImage(NetworkImage(url), width: width, allowUpscaling: false);
+}
+
 class PlayerPageHandoff {
   PlayerPageHandoff({required this.sourceUserWantsPlay});
 
@@ -178,7 +189,9 @@ class _PlayerPageState extends State<PlayerPage>
     _thumbnailService = PlaybackThumbnailService(
       sourceResolver: _resolveThumbnailSource,
     );
-    _spriteAxisService = SpriteThumbnailAxisService(spriteCacheCapacity: 8)
+    // 雪碧图每张解码后是整块位图，保留 3 部剧足够擦洗回退，8 部在低端机
+    // 容易把图片缓存顶满甚至触发 OOM。
+    _spriteAxisService = SpriteThumbnailAxisService(spriteCacheCapacity: 3)
       ..addListener(_handleSpriteFrameChanged);
     WidgetsBinding.instance.addObserver(this);
     logic.start(
@@ -507,9 +520,10 @@ class _PlayerPageState extends State<PlayerPage>
         final imageUrl = AppConfig.mediaUrl(posterUrl);
         if (_precachedPosterUrls.add(imageUrl)) {
           unawaited(
-            precacheImage(NetworkImage(imageUrl), context).catchError((
-              Object _,
-            ) {
+            precacheImage(
+              _posterProvider(imageUrl, width: _posterPreviewWidth),
+              context,
+            ).catchError((Object _) {
               _precachedPosterUrls.remove(imageUrl);
             }),
           );
@@ -728,7 +742,15 @@ class _PlayerPageState extends State<PlayerPage>
         if (logic.pip) {
           final poster = logic.trackedEpisode?.posterUrl?.trim();
           if (poster != null && poster.isNotEmpty) {
-            unawaited(precacheImage(NetworkImage(poster), context));
+            unawaited(
+              precacheImage(
+                _posterProvider(
+                  AppConfig.mediaUrl(poster),
+                  width: _posterPipWidth,
+                ),
+                context,
+              ),
+            );
           }
         }
         return Stack(