fix(player): 预热直出并与视频统一封面布局

lib/pages/player/widgets/player_video_surface.dart

@@ -6,7 +6,6 @@ import 'package:video_player/video_player.dart';
 
 import '../../../core/theme/app_colors.dart';
 
-const Duration _videoFadeDuration = Duration(milliseconds: 200);
 const double _errorHorizontal = 32;
 const int _errorMaxLines = 3;
 
@@ -20,6 +19,7 @@ class PlayerVideoSurface extends StatefulWidget {
     this.handoff,
     this.openingFrame,
     this.holdOpeningUntilFirstFrame = false,
+    this.preparedFrameAvailable = false,
   });
 
   final VideoPlayerController? controller;
@@ -30,6 +30,9 @@ class PlayerVideoSurface extends StatefulWidget {
 
   /// 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;
+
+  /// 相邻集预热槽已持有可用画面，进入页面时不需要封面兜底。
+  final bool preparedFrameAvailable;
   final String videoUrl;
   final bool theater;
 
@@ -69,15 +72,27 @@ class _PlayerVideoSurfaceState extends State<PlayerVideoSurface> {
   Widget _frame(VideoPlayerValue? value) {
     final controller = widget.controller;
     final handoff = _liveHandoff(controller);
-    final firstFrameReady = _trackFrameState(controller, value);
-    final reveal = _shouldReveal(value, handoff != null) &&
+    final firstFrameSeen = _trackFrameState(controller, value);
+    final firstFrameReady =
+        widget.preparedFrameAvailable || firstFrameSeen;
+    final textureReady = _shouldReveal(value, handoff != null);
+    final reveal = textureReady &&
         (!widget.holdOpeningUntilFirstFrame ||
+            widget.preparedFrameAvailable ||
             firstFrameReady ||
             _playbackStarted &&
                 value?.isPlaying == false &&
                 value?.isBuffering != true);
+    final showOpening =
+        widget.openingFrame != null && handoff == null && !reveal;
     _logStateChange(value);
-    _logLayerState(value, handoff, reveal, firstFrameReady);
+    _logLayerState(
+      value,
+      handoff,
+      reveal,
+      firstFrameReady,
+      showOpening,
+    );
     return Stack(
       fit: StackFit.expand,
       children: [
@@ -85,19 +100,15 @@ class _PlayerVideoSurfaceState extends State<PlayerVideoSurface> {
           key: Key('player-fallback-background'),
           color: AppColors.mediaBlack,
         ),
-        if (widget.openingFrame != null)
-          AnimatedOpacity(
+        if (showOpening)
+          KeyedSubtree(
             key: const Key('player-opening-frame'),
-            opacity: reveal ? 0 : 1,
-            duration: handoff != null ? Duration.zero : _videoFadeDuration,
-            curve: Curves.easeOut,
             child: widget.openingFrame!,
           ),
         AnimatedOpacity(
           key: const Key('player-video-opacity'),
           opacity: reveal ? 1 : 0,
-          duration: handoff != null ? Duration.zero : _videoFadeDuration,
-          curve: Curves.easeOut,
+          duration: Duration.zero,
           child: reveal && controller != null
               ? _VideoLayer(
                   controller: controller,
@@ -180,20 +191,24 @@ class _PlayerVideoSurfaceState extends State<PlayerVideoSurface> {
     VideoPlayerController? handoff,
     bool reveal,
     bool firstFrameReady,
+    bool showOpening,
   ) {
     if (!kDebugMode) return;
     final reason = handoff != null
         ? 'handoff'
         : !_shouldReveal(value, handoff != null)
         ? 'uninitialized'
+        : widget.preparedFrameAvailable
+        ? 'warm-frame'
         : !firstFrameReady && widget.holdOpeningUntilFirstFrame
         ? 'awaiting-first-frame'
         : 'reveal';
     final signature =
-        'opening=${widget.openingFrame == null ? 0 : reveal ? 0 : 1} '
+        'warm=${widget.preparedFrameAvailable ? 1 : 0} '
+        'frame=${firstFrameReady ? 1 : 0} '
+        'cover=${showOpening ? 1 : 0} '
         'video=${reveal ? 1 : 0} handoff=${handoff == null ? 0 : 1} '
         'init=${value?.isInitialized == true ? 1 : 0} '
-        'frame=${firstFrameReady ? 1 : 0} '
         'playing=${value?.isPlaying == true ? 1 : 0} '
         'buffering=${value?.isBuffering == true ? 1 : 0} '
         'reason=$reason';