fix(player): 修正缓冲态与首帧时间闪现

test/playback/seek_progress_bar_test.dart

@@ -54,6 +54,11 @@ void main() {
     expect(find.byKey(const Key('progress-loading')), findsNothing);
     expect(find.byKey(const Key('progress-inactive')), findsOneWidget);
     expect(find.byType(Slider), findsNothing);
+    expect(
+      find.byKey(const Key('player-progress-uninitialized-time')),
+      findsNothing,
+    );
+    expect(find.textContaining('00:00'), findsNothing);
   });
 
   testWidgets('should_show_inactive_track_and_disable_seek_when_locked', (
@@ -144,6 +149,119 @@ void main() {
     expect(find.byType(Slider), findsOneWidget);
   });
 
+  testWidgets(
+    'should_hide_buffering_loading_immediately_when_position_advances',
+    (tester) async {
+      final video = ValueNotifier<VideoPlayerValue>(
+        const VideoPlayerValue(
+          duration: Duration(seconds: 12),
+          position: Duration(seconds: 3),
+          isInitialized: true,
+          isPlaying: true,
+          isBuffering: true,
+        ),
+      );
+      addTearDown(video.dispose);
+      await tester.pumpWidget(
+        MaterialApp(
+          home: Scaffold(
+            body: SeekProgressBar(
+              valueListenable: video,
+              semanticsLabel: 'Seek video',
+              onSeek: (_) async {},
+            ),
+          ),
+        ),
+      );
+
+      expect(find.byKey(const Key('progress-loading')), findsNothing);
+      await tester.pump(const Duration(milliseconds: 200));
+      video.value = const VideoPlayerValue(
+        duration: Duration(seconds: 12),
+        position: Duration(seconds: 4),
+        isInitialized: true,
+        isBuffering: true,
+      );
+      await tester.pump();
+      await tester.pump(const Duration(milliseconds: 400));
+
+      expect(find.byKey(const Key('progress-loading')), findsNothing);
+      expect(find.byType(Slider), findsOneWidget);
+
+      video.value = const VideoPlayerValue(
+        duration: Duration(seconds: 12),
+        position: Duration(seconds: 4),
+        isInitialized: true,
+        isPlaying: true,
+        isBuffering: true,
+      );
+      await tester.pump();
+      await tester.pump(const Duration(milliseconds: 400));
+
+      expect(find.byKey(const Key('progress-loading')), findsOneWidget);
+      expect(find.byType(Slider), findsNothing);
+    },
+  );
+
+  testWidgets('should_not_show_loading_for_prewarmed_episode', (tester) async {
+    final video = ValueNotifier<VideoPlayerValue>(
+      const VideoPlayerValue(
+        duration: Duration(seconds: 12),
+        position: Duration(seconds: 5),
+        isInitialized: true,
+        isPlaying: true,
+        isBuffering: true,
+      ),
+    );
+    addTearDown(video.dispose);
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: SeekProgressBar(
+            valueListenable: video,
+            semanticsLabel: 'Seek video',
+            onSeek: (_) async {},
+          ),
+        ),
+      ),
+    );
+
+    await tester.pump(const Duration(milliseconds: 400));
+    expect(find.byKey(const Key('progress-loading')), findsNothing);
+    expect(find.byType(Slider), findsOneWidget);
+  });
+
+  testWidgets(
+    'should_suppress_progress_loading_while_entry_loading_is_visible',
+    (tester) async {
+      final video = ValueNotifier<VideoPlayerValue>(
+        const VideoPlayerValue(
+          duration: Duration(seconds: 12),
+          position: Duration.zero,
+          isInitialized: true,
+          isBuffering: true,
+        ),
+      );
+      addTearDown(video.dispose);
+      await tester.pumpWidget(
+        MaterialApp(
+          home: Scaffold(
+            body: SeekProgressBar(
+              valueListenable: video,
+              semanticsLabel: 'Seek video',
+              suppressBufferLoading: true,
+              onSeek: (_) async {},
+            ),
+          ),
+        ),
+      );
+
+      await tester.pump(const Duration(milliseconds: 400));
+      expect(find.byKey(const Key('progress-loading')), findsNothing);
+      expect(find.byType(Slider), findsOneWidget);
+    },
+  );
+
   testWidgets('should_keep_slider_while_scrubbing_during_buffering', (
     tester,
   ) async {