fix(player): 使用雪碧图预热首帧兜底

lib/core/data/services/sprite_thumbnail_axis.dart

@@ -132,36 +132,37 @@ class SpriteThumbnailAxisService extends ChangeNotifier
   SpriteThumbnailAxisService({
     SpriteThumbnailAssetLoader? loader,
     this.cacheTtl = spriteVttCacheTtl,
+    this.spriteCacheCapacity = spriteImageCacheCapacity,
     DateTime Function()? now,
   }) : _loader = loader ?? DioSpriteThumbnailAssetLoader(),
        _now = now ?? DateTime.now;
 
   final SpriteThumbnailAssetLoader _loader;
   final Duration cacheTtl;
+  final int spriteCacheCapacity;
   final DateTime Function() _now;
   final Map<String, _CachedAxis> _axisCache = {};
   final Map<String, Future<SpriteThumbnailAxis>> _axisRequests = {};
   final LinkedHashMap<String, _CachedSprite> _spriteCache = LinkedHashMap();
   final Map<String, Future<_CachedSprite?>> _spriteRequests = {};
   final Set<String> _failedSprites = {};
-  String? _activeAxisUrl;
-  int _axisGeneration = 0;
   bool _disposed = false;
 
   @visibleForTesting
   int get spriteCacheSize => _spriteCache.length;
 
   @visibleForTesting
-  List<String> get spriteCacheKeys => _spriteCache.keys.toList();
+  List<String> get spriteCacheKeys => _spriteCache.keys
+      .map((url) => Uri.tryParse(url)?.pathSegments.lastOrNull ?? url)
+      .toList();
 
   /// 播放器就绪时预取当前 cue 与相邻 sprite，拖动帧不触发网络或解码。
   @override
   Future<void> prepareAt(String? thumbnailsUrl, Duration position) async {
     final url = _normalizeUrl(thumbnailsUrl);
     if (_disposed || url == null) return;
-    _activateAxis(url);
     final axis = await _loadAxis(url);
-    if (_disposed || _activeAxisUrl != url) return;
+    if (_disposed) return;
     for (final cue in _prefetchCues(axis, position)) {
       await _ensureSprite(axis, cue);
     }
@@ -170,7 +171,7 @@ class SpriteThumbnailAxisService extends ChangeNotifier
   @override
   bool hasAxis(String? thumbnailsUrl) {
     final url = _normalizeUrl(thumbnailsUrl);
-    if (url == null || url != _activeAxisUrl) return false;
+    if (url == null) return false;
     return _readAxis(url) != null;
   }
 
@@ -180,12 +181,14 @@ class SpriteThumbnailAxisService extends ChangeNotifier
     Duration position,
   ) {
     final url = _normalizeUrl(thumbnailsUrl);
-    if (url == null || url != _activeAxisUrl) return null;
+    if (url == null) return null;
     final axis = _readAxis(url);
     if (axis == null) return null;
     final cue = selectSpriteThumbnailCue(axis.cues, position);
     if (cue == null) return null;
-    final cached = _readSprite(cue.spriteFile);
+    final cached = _readSprite(
+      axis.resolveSpriteUri(cue.spriteFile).toString(),
+    );
     if (cached == null) return null;
     final sourceRect = _scaledSourceRect(cached, cue.sourceRect);
     if (sourceRect == null) return null;
@@ -206,13 +209,6 @@ class SpriteThumbnailAxisService extends ChangeNotifier
     super.dispose();
   }
 
-  void _activateAxis(String url) {
-    if (_activeAxisUrl == url) return;
-    _activeAxisUrl = url;
-    _axisGeneration++;
-    _clearSprites();
-  }
-
   Future<SpriteThumbnailAxis> _loadAxis(String url) {
     final cached = _readAxis(url);
     if (cached != null) return Future.value(cached);
@@ -239,7 +235,6 @@ class SpriteThumbnailAxisService extends ChangeNotifier
       } on SpriteThumbnailForbiddenException {
         if (_disposed) return SpriteThumbnailAxis.empty(url);
         _axisCache.remove(url);
-        if (_activeAxisUrl == url) _clearSprites();
       } catch (_) {
         break;
       }
@@ -293,23 +288,23 @@ class SpriteThumbnailAxisService extends ChangeNotifier
     SpriteThumbnailAxis axis,
     SpriteThumbnailCue cue,
   ) {
-    final cached = _readSprite(cue.spriteFile);
+    final spriteUrl = axis.resolveSpriteUri(cue.spriteFile).toString();
+    final cached = _readSprite(spriteUrl);
     if (cached != null) return Future.value(cached);
-    if (_failedSprites.contains(cue.spriteFile)) return Future.value();
+    if (_failedSprites.contains(spriteUrl)) return Future.value();
-    final existing = _spriteRequests[cue.spriteFile];
+    final existing = _spriteRequests[spriteUrl];
     if (existing != null) return existing;
-    final generation = _axisGeneration;
+    final request = _loadSprite(axis, cue, spriteUrl);
-    final request = _loadSprite(axis, cue, generation);
+    _spriteRequests[spriteUrl] = request;
-    _spriteRequests[cue.spriteFile] = request;
     return request.whenComplete(() {
-      _spriteRequests.remove(cue.spriteFile);
+      _spriteRequests.remove(spriteUrl);
     });
   }
 
   Future<_CachedSprite?> _loadSprite(
     SpriteThumbnailAxis axis,
     SpriteThumbnailCue cue,
-    int generation,
+    String spriteUrl,
   ) async {
     SpriteThumbnailDecodedImage? decoded;
     try {
@@ -318,16 +313,16 @@ class SpriteThumbnailAxisService extends ChangeNotifier
       decoded = null;
     }
     if (decoded == null) {
-      _failedSprites.add(cue.spriteFile);
+      _failedSprites.add(spriteUrl);
       if (!_disposed) notifyListeners();
       return null;
     }
-    if (_disposed || generation != _axisGeneration) {
+    if (_disposed) {
       decoded.image.dispose();
       return null;
     }
     final cached = _CachedSprite(decoded);
-    _putSprite(cue.spriteFile, cached);
+    _putSprite(spriteUrl, cached);
     notifyListeners();
     return cached;
   }
@@ -342,7 +337,7 @@ class SpriteThumbnailAxisService extends ChangeNotifier
   void _putSprite(String key, _CachedSprite value) {
     _spriteCache.remove(key)?.decoded.image.dispose();
     _spriteCache[key] = value;
-    while (_spriteCache.length > spriteImageCacheCapacity) {
+    while (_spriteCache.length > spriteCacheCapacity) {
       final oldest = _spriteCache.remove(_spriteCache.keys.first);
       oldest?.decoded.image.dispose();
     }
@@ -378,8 +373,6 @@ class SpriteThumbnailAxisService extends ChangeNotifier
   }
 
   void _clearAll() {
-    _axisGeneration++;
-    _activeAxisUrl = null;
     _axisCache.clear();
     _axisRequests.clear();
     _clearSprites();

lib/pages/player/player_view.dart

@@ -146,7 +146,9 @@ class _PlayerPageState extends State<PlayerPage>
     _thumbnailService = PlaybackThumbnailService(
       sourceResolver: _resolveThumbnailSource,
     );
-    _spriteAxisService = SpriteThumbnailAxisService();
+    _spriteAxisService = SpriteThumbnailAxisService(
+      spriteCacheCapacity: 8,
+    )..addListener(_handleSpriteFrameChanged);
     WidgetsBinding.instance.addObserver(this);
     logic.start(
       factory: context.read<PlayerFactory>(),
@@ -266,7 +268,9 @@ class _PlayerPageState extends State<PlayerPage>
   void dispose() {
     WidgetsBinding.instance.removeObserver(this);
     appRouteObserver.unsubscribe(this);
-    _spriteAxisService.dispose();
+    _spriteAxisService
+      ..removeListener(_handleSpriteFrameChanged)
+      ..dispose();
     _thumbnailService.dispose();
     logic.dispose();
     super.dispose();
@@ -369,6 +373,30 @@ class _PlayerPageState extends State<PlayerPage>
     _chromeVisible = true;
   }
 
+  void _handleSpriteFrameChanged() {
+    if (mounted) setState(() {});
+  }
+
+  void _prewarmAdjacentThumbnails() {
+    final current = logic.session.currentIndex;
+    final indices = <int?>[
+      current,
+      logic.previousVisibleIndex(current),
+      logic.nextVisibleIndex(current),
+    ];
+    for (final index in indices) {
+      if (index == null || index < 0 || index >= logic.sessionEpisodes.length) {
+        continue;
+      }
+      final thumbnailsUrl = logic.sessionEpisodes[index].thumbnailsUrl;
+      if (thumbnailsUrl != null) {
+        unawaited(
+          _spriteAxisService.prepareAt(thumbnailsUrl, Duration.zero),
+        );
+      }
+    }
+  }
+
   void _restoreFeedChrome() {
     if (!mounted) return;
     setState(() {
@@ -451,6 +479,7 @@ class _PlayerPageState extends State<PlayerPage>
     final content = AnimatedBuilder(
       animation: logic.session,
       builder: (context, _) {
+        _prewarmAdjacentThumbnails();
         final pages = NotificationListener<ScrollNotification>(
           onNotification: _handlePageScroll,
           child: PageView.builder(
@@ -590,6 +619,15 @@ class _PlayerPageState extends State<PlayerPage>
     final videoFit = theater ? BoxFit.contain : BoxFit.cover;
     final preparedFrameAvailable =
         selected && logic.session.reusedWarmAt(index);
+    final thumbnailsUrl = episode.thumbnailsUrl;
+    final openingFrameReady =
+        thumbnailsUrl != null &&
+        _spriteAxisService.cachedFrameAt(thumbnailsUrl, Duration.zero) != null;
+    if (thumbnailsUrl != null) {
+      unawaited(
+        _spriteAxisService.prepareAt(thumbnailsUrl, Duration.zero),
+      );
+    }
     final locked = logic.session.isLocked || episode.locked;
     if (selected &&
         videoPort != null &&
@@ -617,9 +655,10 @@ class _PlayerPageState extends State<PlayerPage>
           theater: theater,
           holdOpeningUntilFirstFrame: logic.session.userWantsPlay,
           preparedFrameAvailable: preparedFrameAvailable,
+          openingFrameReady: openingFrameReady,
           openingFrame: playerOpeningFrame(
-            episode.thumbnailsUrl,
+            thumbnailsUrl,
-            posterUrl: drama.posterUrl,
+            spriteSource: _spriteAxisService,
             fit: videoFit,
           ),
         ),

lib/pages/player/widgets/home_feed_overlay.dart

@@ -217,7 +217,6 @@ class _HomeFeedOverlayState extends State<HomeFeedOverlay> {
               spriteAxisService: widget.spriteAxisService,
               thumbnailsUrl: widget.episode.thumbnailsUrl,
               episodeId: widget.episode.id,
-              posterUrl: widget.drama.posterUrl,
               onScrubStart: _startScrub,
               onScrubEnd: _endScrub,
               onSeek: widget.onSeek,

lib/pages/player/widgets/home_feed_overlay_parts.dart

@@ -23,7 +23,6 @@ class _FeedProgressBar extends StatefulWidget {
     this.spriteAxisService,
     this.thumbnailsUrl,
     this.episodeId,
-    this.posterUrl = '',
     this.onScrubStart,
     this.onScrubEnd,
     this.onSeek,
@@ -38,7 +37,6 @@ class _FeedProgressBar extends StatefulWidget {
   final SpriteThumbnailAxisSource? spriteAxisService;
   final String? thumbnailsUrl;
   final String? episodeId;
-  final String posterUrl;
   final VoidCallback? onScrubStart;
   final VoidCallback? onScrubEnd;
   final ValueChanged<Duration>? onSeek;
@@ -166,7 +164,6 @@ class _FeedProgressBarState extends State<_FeedProgressBar> {
                       spriteAxisService: widget.spriteAxisService,
                       thumbnailsUrl: widget.thumbnailsUrl,
                       episodeId: widget.episodeId!,
-                      posterUrl: widget.posterUrl,
                       position: previewPosition,
                       duration: video!.duration,
                     ),

lib/pages/player/widgets/player_opening_frame.dart

@@ -1,199 +1,97 @@
 // Author: fruit.com.cn
 
 import 'dart:async';
-import 'dart:ui' as ui;
 
 import 'package:flutter/material.dart';
 
-import '../../../core/config/app_config.dart';
-import '../../../core/data/services/sprite_thumbnail_asset_loader.dart';
 import '../../../core/data/services/sprite_thumbnail_axis.dart';
 import '../../../core/theme/app_colors.dart';
-import '../../../core/widgets/remote_image.dart';
 import 'scrub_preview_card.dart';
 
-/// 封面立即可见，雪碧图首帧解码完成后再覆盖封面。
+/// 当前集雪碧图首帧在视频纹理未就绪时占位；空地址交还纯黑底。
 Widget? playerOpeningFrame(
   String? thumbnailsUrl, {
-  String? posterUrl,
+  required SpriteThumbnailAxisSource spriteSource,
   BoxFit fit = BoxFit.cover,
 }) {
   final url = thumbnailsUrl?.trim() ?? '';
-  final poster = posterUrl?.trim() ?? '';
+  if (url.isEmpty) return null;
-  if (url.isEmpty && poster.isEmpty) return null;
   return PlayerOpeningFrame(
-    thumbnailsUrl: url.isEmpty ? null : url,
+    thumbnailsUrl: url,
-    posterUrl: poster.isEmpty ? null : poster,
+    spriteSource: spriteSource,
     fit: fit,
   );
 }
 
-/// 视频解码前依次使用封面和雪碧图首帧，最终由父层黑色兜底。
+/// 与视频共用全屏父约束和 BoxFit，切换时保持相同可见区域。
 class PlayerOpeningFrame extends StatefulWidget {
   const PlayerOpeningFrame({
     super.key,
-    this.thumbnailsUrl,
+    required this.thumbnailsUrl,
-    this.posterUrl,
+    required this.spriteSource,
     this.fit = BoxFit.cover,
-    this.loader,
-    this.cache,
   });
 
-  final String? thumbnailsUrl;
+  /// 当前视频雪碧图 WebVTT 地址。
-  final String? posterUrl;
+  final String thumbnailsUrl;
+
+  /// 进度条拖动预览共用的雪碧图时间轴与解码缓存。
+  final SpriteThumbnailAxisSource spriteSource;
+
+  /// 必须与同页视频层使用相同适配规则。
   final BoxFit fit;
-  final SpriteThumbnailAssetLoader? loader;
-  final OpeningFrameCache? cache;
 
   @override
   State<PlayerOpeningFrame> createState() => _PlayerOpeningFrameState();
 }
 
 class _PlayerOpeningFrameState extends State<PlayerOpeningFrame> {
-  SpriteThumbnailFrame? _frame;
-  int _serial = 0;
-
   @override
   void initState() {
     super.initState();
-    unawaited(_load());
+    widget.spriteSource.addListener(_handleSpriteChanged);
+    unawaited(
+      widget.spriteSource.prepareAt(widget.thumbnailsUrl, Duration.zero),
+    );
   }
 
   @override
   void didUpdateWidget(covariant PlayerOpeningFrame oldWidget) {
     super.didUpdateWidget(oldWidget);
+    if (oldWidget.spriteSource != widget.spriteSource) {
+      oldWidget.spriteSource.removeListener(_handleSpriteChanged);
+      widget.spriteSource.addListener(_handleSpriteChanged);
+    }
     if (oldWidget.thumbnailsUrl != widget.thumbnailsUrl) {
-      _frame = null;
+      unawaited(
-      unawaited(_load());
+        widget.spriteSource.prepareAt(widget.thumbnailsUrl, Duration.zero),
+      );
     }
-  }
-
-  Future<void> _load() async {
-    final serial = ++_serial;
-    final thumbnailsUrl = widget.thumbnailsUrl;
-    if (thumbnailsUrl == null) return;
-    final frame = await (widget.cache ?? OpeningFrameCache.shared).load(
-      thumbnailsUrl,
-      loader: widget.loader,
-    );
-    if (!mounted || serial != _serial) return;
-    setState(() => _frame = frame);
   }
 
   @override
-  Widget build(BuildContext context) {
+  void dispose() {
-    final frame = _frame;
+    widget.spriteSource.removeListener(_handleSpriteChanged);
-    final posterUrl = widget.posterUrl;
+    super.dispose();
-    return Stack(
-      fit: StackFit.expand,
-      children: [
-        const ColoredBox(color: AppColors.mediaBlack),
-        if (posterUrl != null)
-          RemoteImage(
-            posterUrl,
-            key: const Key('player-opening-poster'),
-            fit: widget.fit,
-            fallbackColor: AppColors.mediaBlack,
-          ),
-        if (frame != null)
-          SpriteCropPreview(
-            key: const Key('player-opening-sprite'),
-            image: frame.image,
-            sourceRect: frame.sourceRect,
-            fit: widget.fit,
-          ),
-      ],
-    );
-  }
-}
-
-/// 相邻页共用的雪碧图首帧缓存，避免每页重复拉 VTT。
-class OpeningFrameCache {
-  OpeningFrameCache({this.capacity = 6});
-
-  static final OpeningFrameCache shared = OpeningFrameCache();
-
-  final int capacity;
-  final Map<String, SpriteThumbnailFrame> _frames = {};
-  final Map<String, Future<SpriteThumbnailFrame?>> _loads = {};
-
-  /// 取 [thumbnailsUrl] 对应的第一帧；失败返回 null。
-  Future<SpriteThumbnailFrame?> load(
-    String? thumbnailsUrl, {
-    SpriteThumbnailAssetLoader? loader,
-  }) {
-    final url = _normalize(thumbnailsUrl);
-    if (url == null) return Future<SpriteThumbnailFrame?>.value();
-    final cached = _frames[url];
-    if (cached != null) return Future.value(cached);
-    return _loads.putIfAbsent(url, () => _fetch(url, loader));
-  }
-
-  Future<SpriteThumbnailFrame?> _fetch(
-    String url,
-    SpriteThumbnailAssetLoader? loader,
-  ) async {
-    try {
-      final asset = loader ?? DioSpriteThumbnailAssetLoader();
-      final text = await asset.loadVtt(Uri.parse(url));
-      if (text == null || text.isEmpty) return null;
-      final axis = parseSpriteThumbnailVtt(text, vttUrl: url);
-      final cue = axis.cues.isEmpty ? null : axis.cues.first;
-      if (cue == null) return null;
-      final decoded = await asset.loadSprite(
-        axis.resolveSpriteUri(cue.spriteFile),
-      );
-      if (decoded == null) return null;
-      final frame = SpriteThumbnailFrame(
-        image: decoded.image,
-        sourceRect: _scaledRect(decoded, cue.sourceRect),
-        spriteUrl: axis.resolveSpriteUri(cue.spriteFile).toString(),
-        cue: cue,
-      );
-      _store(url, frame);
-      return frame;
-    } catch (_) {
-      return null;
-    } finally {
-      _loads.remove(url);
-    }
-  }
-
-  void _store(String url, SpriteThumbnailFrame frame) {
-    _frames.remove(url);
-    _frames[url] = frame;
-    while (_frames.length > capacity) {
-      final oldest = _frames.keys.first;
-      _frames.remove(oldest)?.image.dispose();
-    }
-  }
-
-  ui.Rect _scaledRect(SpriteThumbnailDecodedImage decoded, ui.Rect source) {
-    if (decoded.originalWidth <= 0 || decoded.originalHeight <= 0) {
-      return source;
-    }
-    final scaleX = decoded.image.width / decoded.originalWidth;
-    final scaleY = decoded.image.height / decoded.originalHeight;
-    return ui.Rect.fromLTWH(
-      source.left * scaleX,
-      source.top * scaleY,
-      source.width * scaleX,
-      source.height * scaleY,
-    );
-  }
-
-  String? _normalize(String? raw) {
-    final value = AppConfig.mediaUrl(raw?.trim() ?? '');
-    if (value.isEmpty) return null;
-    return value;
-  }
-
-  /// 测试收尾时清空缓存。
-  void clear() {
-    for (final frame in _frames.values) {
-      frame.image.dispose();
-    }
-    _frames.clear();
-    _loads.clear();
   }
+
+  void _handleSpriteChanged() {
+    if (mounted) setState(() {});
+  }
+
+  @override
+  Widget build(BuildContext context) => Stack(
+    fit: StackFit.expand,
+    children: [
+      const ColoredBox(color: AppColors.mediaBlack),
+      if (widget.spriteSource.cachedFrameAt(widget.thumbnailsUrl, Duration.zero)
+          case final frame?)
+        SpriteCropPreview(
+          key: const Key('player-opening-sprite'),
+          image: frame.image,
+          sourceRect: frame.sourceRect,
+          fit: widget.fit,
+        ),
+    ],
+  );
 }

lib/pages/player/widgets/player_overlay.dart

@@ -303,7 +303,6 @@ class PlayerPlaybackOverlay extends StatelessWidget {
         spriteAxisService: data.spriteAxisService,
         thumbnailsUrl: data.episode.thumbnailsUrl,
         episodeId: data.episode.id,
-        posterUrl: data.drama.posterUrl,
         inactiveTrackColor: AppColors.inactiveTrack,
         onScrubStart: actions.onScrubStart,
         onScrubEnd: actions.onScrubEnd,

lib/pages/player/widgets/player_video_surface.dart

@@ -18,6 +18,7 @@ class PlayerVideoSurface extends StatefulWidget {
     required this.theater,
     this.handoff,
     this.openingFrame,
+    this.openingFrameReady = false,
     this.holdOpeningUntilFirstFrame = false,
     this.preparedFrameAvailable = false,
   });
@@ -28,6 +29,9 @@ class PlayerVideoSurface extends StatefulWidget {
   /// 解码出第一帧之前垫上的视频首帧，没有则为空。
   final Widget? openingFrame;
 
+  /// 当前集雪碧图 t=0 是否已在共享缓存中可用。
+  final bool openingFrameReady;
+
   /// 播放中的新片源在位置首次前进前继续显示封面，避免混入未出帧纹理。
   final bool holdOpeningUntilFirstFrame;
 
@@ -73,10 +77,10 @@ class _PlayerVideoSurfaceState extends State<PlayerVideoSurface> {
     final controller = widget.controller;
     final handoff = _liveHandoff(controller);
     final firstFrameSeen = _trackFrameState(controller, value);
-    final firstFrameReady =
+    final firstFrameReady = widget.preparedFrameAvailable || firstFrameSeen;
-        widget.preparedFrameAvailable || firstFrameSeen;
     final textureReady = _shouldReveal(value, handoff != null);
-    final reveal = textureReady &&
+    final reveal =
+        textureReady &&
         (!widget.holdOpeningUntilFirstFrame ||
             widget.preparedFrameAvailable ||
             firstFrameReady ||
@@ -86,13 +90,7 @@ class _PlayerVideoSurfaceState extends State<PlayerVideoSurface> {
     final showOpening =
         widget.openingFrame != null && handoff == null && !reveal;
     _logStateChange(value);
-    _logLayerState(
+    _logLayerState(value, handoff, reveal, firstFrameReady, showOpening);
-      value,
-      handoff,
-      reveal,
-      firstFrameReady,
-      showOpening,
-    );
     return Stack(
       fit: StackFit.expand,
       children: [
@@ -203,10 +201,20 @@ class _PlayerVideoSurfaceState extends State<PlayerVideoSurface> {
         : !firstFrameReady && widget.holdOpeningUntilFirstFrame
         ? 'awaiting-first-frame'
         : 'reveal';
+    final fallback = handoff != null
+        ? 'handoff'
+        : showOpening
+        ? widget.openingFrameReady
+              ? 'thumbnails-first-frame'
+              : 'black'
+        : reveal
+        ? 'video'
+        : 'black';
     final signature =
         'warm=${widget.preparedFrameAvailable ? 1 : 0} '
         'frame=${firstFrameReady ? 1 : 0} '
-        'cover=${showOpening ? 1 : 0} '
+        'thumbnails=${widget.openingFrameReady ? 'ready' : 'pending'} '
+        'fallback=$fallback '
         'video=${reveal ? 1 : 0} handoff=${handoff == null ? 0 : 1} '
         'init=${value?.isInitialized == true ? 1 : 0} '
         'playing=${value?.isPlaying == true ? 1 : 0} '

lib/pages/player/widgets/scrub_preview_card.dart

@@ -9,7 +9,6 @@ import 'package:flutter/material.dart';
 import '../../../core/data/services/playback_thumbnail_service.dart';
 import '../../../core/data/services/sprite_thumbnail_axis.dart';
 import '../../../core/theme/app_colors.dart';
-import '../../../core/widgets/remote_image.dart';
 
 const double scrubPreviewWidth = 96;
 const double scrubPreviewSafeMargin = 12;
@@ -36,7 +35,6 @@ class ScrubPreviewCard extends StatefulWidget {
     super.key,
     required this.service,
     required this.episodeId,
-    required this.posterUrl,
     required this.position,
     required this.duration,
     this.spriteAxisService,
@@ -47,7 +45,6 @@ class ScrubPreviewCard extends StatefulWidget {
   final SpriteThumbnailAxisSource? spriteAxisService;
   final String? thumbnailsUrl;
   final String episodeId;
-  final String posterUrl;
   final Duration position;
   final Duration duration;
 
@@ -207,11 +204,9 @@ class _ScrubPreviewCardState extends State<ScrubPreviewCard> {
               child: Stack(
                 fit: StackFit.expand,
                 children: [
-                  RemoteImage(
+                  const ColoredBox(
-                    widget.posterUrl,
+                    key: Key('scrub-preview-background'),
-                    key: const Key('scrub-preview-poster'),
+                    color: AppColors.bar,
-                    fit: BoxFit.cover,
-                    fallbackColor: AppColors.bar,
                   ),
                   if (stage == ScrubPreviewStage.sprite && spriteFrame != null)
                     SpriteCropPreview(
@@ -265,11 +260,7 @@ class SpriteCropPreview extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) => CustomPaint(
-    painter: _SpriteCropPainter(
+    painter: _SpriteCropPainter(image: image, sourceRect: sourceRect, fit: fit),
-      image: image,
-      sourceRect: sourceRect,
-      fit: fit,
-    ),
   );
 }
 

lib/pages/player/widgets/seek_progress_bar.dart

@@ -41,7 +41,6 @@ class SeekProgressBar extends StatefulWidget {
     this.thumbnailService,
     this.spriteAxisService,
     this.episodeId,
-    this.posterUrl = '',
     this.thumbnailsUrl,
   });
 
@@ -57,7 +56,6 @@ class SeekProgressBar extends StatefulWidget {
   final PlaybackThumbnailService? thumbnailService;
   final SpriteThumbnailAxisService? spriteAxisService;
   final String? episodeId;
-  final String posterUrl;
   final String? thumbnailsUrl;
 
   @override
@@ -351,7 +349,6 @@ class _SeekProgressBarState extends State<SeekProgressBar> {
                   spriteAxisService: widget.spriteAxisService,
                   thumbnailsUrl: widget.thumbnailsUrl,
                   episodeId: widget.episodeId!,
-                  posterUrl: widget.posterUrl,
                   position: previewPosition,
                   duration: video.duration,
                 ),

test/playback/seek_progress_bar_test.dart

@@ -249,9 +249,7 @@ void main() {
     },
   );
 
-  testWidgets('should_show_frame_card_with_cover_then_hide_on_release', (
+  testWidgets('should_show_frame_card_then_hide_on_release', (tester) async {
-    tester,
-  ) async {
     final video = ValueNotifier<VideoPlayerValue>(
       const VideoPlayerValue(
         duration: Duration(seconds: 12),
@@ -272,7 +270,6 @@ void main() {
                 valueListenable: video,
                 semanticsLabel: 'Seek video',
                 episodeId: 'episode-1',
-                posterUrl: '',
                 thumbnailService: service,
                 onSeek: (_) async {},
               ),
@@ -289,7 +286,7 @@ void main() {
     await tester.pump();
 
     expect(find.byKey(const Key('scrub-preview-card')), findsOneWidget);
-    expect(find.byKey(const Key('scrub-preview-poster')), findsOneWidget);
+    expect(find.byKey(const Key('scrub-preview-background')), findsOneWidget);
     expect(find.byKey(const Key('scrub-preview-frame')), findsNothing);
     expect(find.textContaining('/ 00:12'), findsOneWidget);
     expect(

test/playback/sprite_thumbnail_axis_test.dart

@@ -114,6 +114,32 @@ void main() {
     expect(service.hasAxis('https://cdn.test/thumbnails.vtt'), isTrue);
   });
 
+  testWidgets('should_keep_zero_frames_ready_across_neighbor_episodes', (
+    tester,
+  ) async {
+    final loader = _FakeSpriteLoader(vtt: _spriteVtt);
+    final service = SpriteThumbnailAxisService(
+      loader: loader,
+      spriteCacheCapacity: 6,
+    );
+    addTearDown(service.dispose);
+    const current = 'https://cdn.test/episode-1/thumbnails.vtt';
+    const previous = 'https://cdn.test/episode-0/thumbnails.vtt';
+    const next = 'https://cdn.test/episode-2/thumbnails.vtt';
+
+    await Future.wait([
+      service.prepareAt(previous, Duration.zero),
+      service.prepareAt(current, Duration.zero),
+      service.prepareAt(next, Duration.zero),
+    ]);
+
+    for (final url in [previous, current, next]) {
+      expect(service.hasAxis(url), isTrue);
+      expect(service.cachedFrameAt(url, Duration.zero), isNotNull);
+    }
+    expect(loader.spriteCalls, hasLength(6));
+  });
+
   testWidgets('should_refresh_vtt_after_ten_minute_ttl', (tester) async {
     var now = DateTime(2026, 10, 22);
     final loader = _FakeSpriteLoader(vtt: _spriteVtt);

test/player/player_opening_frame_test.dart

@@ -5,8 +5,9 @@ import 'dart:ui' as ui;
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:fruitshorts/core/data/services/sprite_thumbnail_asset_loader.dart';
-import 'package:fruitshorts/core/widgets/remote_image.dart';
+import 'package:fruitshorts/core/data/services/sprite_thumbnail_axis.dart';
 import 'package:fruitshorts/pages/player/widgets/player_opening_frame.dart';
+import 'package:fruitshorts/pages/player/widgets/scrub_preview_card.dart';
 
 const String _spriteVtt = '''
 WEBVTT
@@ -16,49 +17,46 @@ sprite_001.jpg#xywh=0,0,160,90
 ''';
 
 void main() {
-  test('should_return_no_opening_frame_when_thumbnails_url_is_empty', () {
+  testWidgets('should_return_no_opening_frame_when_thumbnails_is_empty', (
-    expect(playerOpeningFrame(null, posterUrl: '  '), isNull);
+    tester,
-    expect(playerOpeningFrame('  '), isNull);
+  ) async {
+    final service = SpriteThumbnailAxisService(loader: _FakeSpriteLoader());
+    addTearDown(service.dispose);
+
+    expect(playerOpeningFrame(null, spriteSource: service), isNull);
+    expect(playerOpeningFrame('  ', spriteSource: service), isNull);
   });
 
-  test('should_keep_opening_frame_when_only_poster_is_available', () {
+  testWidgets('should_render_prewarmed_zero_frame_from_shared_cache', (
-    expect(
+    tester,
-      playerOpeningFrame(null, posterUrl: 'https://cdn.test/poster.jpg'),
+  ) async {
-      isA<PlayerOpeningFrame>(),
-    );
-  });
-
-  testWidgets('should_load_and_reuse_first_sprite_frame', (tester) async {
     final loader = _FakeSpriteLoader();
-    final cache = OpeningFrameCache();
+    final service = SpriteThumbnailAxisService(loader: loader);
-    addTearDown(cache.clear);
+    addTearDown(service.dispose);
+    const url = 'https://cdn.test/thumbnails.vtt';
+    await service.prepareAt(url, Duration.zero);
 
-    final first = await cache.load(
+    await tester.pumpWidget(
-      'https://cdn.test/thumbnails.vtt',
+      MaterialApp(
-      loader: loader,
+        home: PlayerOpeningFrame(thumbnailsUrl: url, spriteSource: service),
-    );
+      ),
-    final second = await cache.load(
-      'https://cdn.test/thumbnails.vtt',
-      loader: loader,
     );
+    await tester.pump();
 
-    expect(first, isNotNull);
+    expect(find.byKey(const Key('player-opening-sprite')), findsOneWidget);
-    expect(second, same(first));
     expect(loader.vttCalls, 1);
     expect(loader.spriteCalls, ['sprite_001.jpg']);
   });
 
-  testWidgets('should_render_decoded_opening_frame', (tester) async {
+  testWidgets('should_load_sprite_when_not_prewarmed', (tester) async {
-    final loader = _FakeSpriteLoader();
+    final service = SpriteThumbnailAxisService(loader: _FakeSpriteLoader());
-    final cache = OpeningFrameCache();
+    addTearDown(service.dispose);
-    addTearDown(cache.clear);
 
     await tester.pumpWidget(
       MaterialApp(
         home: PlayerOpeningFrame(
           thumbnailsUrl: 'https://cdn.test/thumbnails.vtt',
-          loader: loader,
+          spriteSource: service,
-          cache: cache,
         ),
       ),
     );
@@ -67,80 +65,26 @@ void main() {
     expect(find.byKey(const Key('player-opening-sprite')), findsOneWidget);
   });
 
-  testWidgets('should_show_poster_while_sprite_is_loading', (tester) async {
+  testWidgets('should_use_same_fit_for_sprite_and_video', (tester) async {
-    final cache = OpeningFrameCache();
+    final service = SpriteThumbnailAxisService(loader: _FakeSpriteLoader());
-    addTearDown(cache.clear);
+    addTearDown(service.dispose);
+    const url = 'https://cdn.test/thumbnails.vtt';
+    await service.prepareAt(url, Duration.zero);
 
     await tester.pumpWidget(
       MaterialApp(
         home: PlayerOpeningFrame(
-          thumbnailsUrl: 'https://cdn.test/thumbnails.vtt',
+          thumbnailsUrl: url,
-          posterUrl: 'https://cdn.test/poster.jpg',
+          spriteSource: service,
-          loader: _FakeSpriteLoader(),
+          fit: BoxFit.contain,
-          cache: cache,
         ),
       ),
     );
 
-    expect(find.byKey(const Key('player-opening-poster')), findsOneWidget);
+    final preview = tester.widget<SpriteCropPreview>(
-  });
+      find.byKey(const Key('player-opening-sprite')),
-
-  testWidgets('should_use_surface_fit_without_extra_frame_constraint', (
-    tester,
-  ) async {
-    await tester.pumpWidget(
-      const MaterialApp(
-        home: PlayerOpeningFrame(
-          posterUrl: 'https://cdn.test/poster.jpg',
-        ),
-      ),
     );
-
+    expect(preview.fit, BoxFit.contain);
-    final poster = tester.widget<RemoteImage>(
-      find.byKey(const Key('player-opening-poster')),
-    );
-
-    expect(poster.fit, BoxFit.cover);
-    expect(find.byType(AspectRatio), findsNothing);
-  });
-
-  test('should_forward_video_fit_to_opening_frame', () {
-    final frame = playerOpeningFrame(
-      null,
-      posterUrl: 'https://cdn.test/poster.jpg',
-      fit: BoxFit.contain,
-    );
-
-    expect(frame, isA<PlayerOpeningFrame>());
-    expect((frame! as PlayerOpeningFrame).fit, BoxFit.contain);
-  });
-
-  testWidgets('should_reuse_decoded_sprite_when_parent_rebuilds', (
-    tester,
-  ) async {
-    final loader = _FakeSpriteLoader();
-    final cache = OpeningFrameCache();
-    addTearDown(cache.clear);
-    Widget build() => MaterialApp(
-      home: PlayerOpeningFrame(
-        thumbnailsUrl: 'https://cdn.test/thumbnails.vtt',
-        posterUrl: 'https://cdn.test/poster.jpg',
-        loader: loader,
-        cache: cache,
-      ),
-    );
-
-    await tester.pumpWidget(build());
-    await tester.pumpAndSettle();
-    expect(loader.vttCalls, 1);
-    expect(loader.spriteCalls, hasLength(1));
-
-    await tester.pumpWidget(build());
-    await tester.pumpAndSettle();
-
-    expect(loader.vttCalls, 1);
-    expect(loader.spriteCalls, hasLength(1));
-    expect(find.byKey(const Key('player-opening-sprite')), findsOneWidget);
   });
 }
 

test/player/scrub_preview_card_test.dart

@@ -67,13 +67,11 @@ void main() {
     await tester.pump();
 
     expect(loader.calls, 1);
-    expect(find.byKey(const Key('scrub-preview-poster')), findsOneWidget);
+    expect(find.byKey(const Key('scrub-preview-background')), findsOneWidget);
     expect(find.byKey(const Key('scrub-preview-sprite')), findsNothing);
   });
 
-  testWidgets('should_keep_poster_when_axis_and_local_frame_both_fail', (
+  testWidgets('should_keep_background_when_frames_both_fail', (tester) async {
-    tester,
-  ) async {
     final loader = _CountingThumbnailLoader();
     final localService = _localService(loader);
     final axis = _FakeAxisSource(axisReady: true);
@@ -90,7 +88,7 @@ void main() {
     await tester.pump();
 
     expect(loader.calls, 1);
-    expect(find.byKey(const Key('scrub-preview-poster')), findsOneWidget);
+    expect(find.byKey(const Key('scrub-preview-background')), findsOneWidget);
     expect(find.byKey(const Key('scrub-preview-sprite')), findsNothing);
     expect(find.byKey(const Key('scrub-preview-frame')), findsNothing);
   });
@@ -109,7 +107,6 @@ Widget _card({
           spriteAxisService: axis,
           thumbnailsUrl: thumbnailsUrl,
           episodeId: 'episode-1',
-          posterUrl: '',
           position: const Duration(seconds: 1),
           duration: const Duration(seconds: 10),
         ),