fix(playback): prevent spurious seek jumps

close #946

android/app/src/main/kotlin/com/edde746/plezy/exoplayer/ExoPlayerCore.kt

@@ -649,6 +649,16 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
     positionUpdateRunnable = null
   }
 
+  private fun resetPlaybackProgress(startPositionMs: Long) {
+    lastPosition = startPositionMs
+    lastDuration = 0L
+    lastBufferedPosition = 0L
+    delegate?.onPropertyChange("time-pos", startPositionMs / 1000.0)
+    delegate?.onPropertyChange("duration", 0.0)
+    delegate?.onPropertyChange("demuxer-cache-time", 0.0)
+    delegate?.onPropertyChange("eof-reached", false)
+  }
+
   private fun emitSeekable(seekable: Boolean, force: Boolean = false) {
     if (!force && lastSeekable == seekable) return
     lastSeekable = seekable
@@ -1380,6 +1390,7 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
     currentMediaUri = uri
     currentHeaders = headers
     currentMediaIsLive = isLive
+    resetPlaybackProgress(startPositionMs)
 
     // Apply auth/custom headers to the HTTP DataSource for this session
     httpDataSourceFactory?.setDefaultRequestProperties(
@@ -1530,7 +1541,16 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
   }
 
   fun seekTo(positionMs: Long) {
-    exoPlayer?.seekTo(positionMs)
+    val player = exoPlayer ?: return
+    val durationMs = player.duration
+    val clampedPositionMs = if (!currentMediaIsLive && durationMs != C.TIME_UNSET && durationMs > 0L) {
+      positionMs.coerceIn(0L, durationMs)
+    } else {
+      positionMs.coerceAtLeast(0L)
+    }
+    player.seekTo(clampedPositionMs)
+    lastPosition = clampedPositionMs
+    delegate?.onPropertyChange("time-pos", clampedPositionMs / 1000.0)
   }
 
   fun setVolume(volume: Float) {

lib/mpv/player/platform/player_android.dart

@@ -98,6 +98,8 @@ class PlayerAndroid extends PlayerBase {
   }) async {
     if (disposed) return;
     await _ensureInitialized();
+    final startPosition = media.start ?? Duration.zero;
+    resetPlaybackProgress(startPosition);
     setSeekable(false);
 
     // Show the video layer
@@ -106,7 +108,7 @@ class PlayerAndroid extends PlayerBase {
     await invoke('open', {
       'uri': media.uri,
       'headers': media.headers,
-      'startPositionMs': media.start?.inMilliseconds ?? 0,
+      'startPositionMs': startPosition.inMilliseconds,
       'autoPlay': play,
       'isLive': isLive,
       if (externalSubtitles != null && externalSubtitles.isNotEmpty)

lib/mpv/player/player_base.dart

@@ -484,6 +484,23 @@ abstract class PlayerBase with PlayerStreamControllersMixin implements Player {
     seekableController.add(seekable);
   }
 
+  @protected
+  void resetPlaybackProgress(Duration position) {
+    _positionMs = position.inMilliseconds;
+    _state = _state.copyWith(
+      completed: false,
+      position: position,
+      duration: Duration.zero,
+      buffer: Duration.zero,
+      bufferRanges: const [],
+    );
+    completedController.add(false);
+    positionController.add(position);
+    durationController.add(Duration.zero);
+    bufferController.add(Duration.zero);
+    bufferRangesController.add(const []);
+  }
+
   @protected
   Future<T?> invoke<T>(String method, [dynamic args]) async {
     if (_disposed) return null;

lib/widgets/video_controls/widgets/timeline_slider.dart

@@ -236,6 +236,7 @@ class _TimelineSliderState extends State<TimelineSlider> {
             disableScale: true,
             focusColor: Colors.transparent,
             semanticLabel: t.videoControls.timelineSlider,
+            descendantsAreFocusable: false,
             child: slider,
           );
         }

test/utils/player_utils_test.dart

@@ -1,4 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
+import 'package:plezy/mpv/mpv.dart' show Player, PlayerState;
 import 'package:plezy/utils/player_utils.dart';
 
 void main() {
@@ -12,4 +13,36 @@ void main() {
       expect(shouldRestartBeforePreviousItem(const Duration(milliseconds: 3001)), isTrue);
     });
   });
+
+  group('clampSeekPosition', () {
+    test('clamps negative positions to zero', () {
+      final player = _FakePlayer(duration: const Duration(minutes: 5));
+
+      expect(clampSeekPosition(player, const Duration(seconds: -10)), Duration.zero);
+    });
+
+    test('clamps positions beyond a known duration', () {
+      final player = _FakePlayer(duration: const Duration(minutes: 5));
+
+      expect(clampSeekPosition(player, const Duration(minutes: 6)), const Duration(minutes: 5));
+    });
+
+    test('does not upper-clamp when duration is unknown', () {
+      final player = _FakePlayer(duration: Duration.zero);
+
+      expect(clampSeekPosition(player, const Duration(minutes: 6)), const Duration(minutes: 6));
+    });
+  });
+}
+
+class _FakePlayer implements Player {
+  _FakePlayer({required Duration duration}) : _state = PlayerState(duration: duration);
+
+  final PlayerState _state;
+
+  @override
+  PlayerState get state => _state;
+
+  @override
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }

test/widgets/video_controls_test.dart

@@ -1,9 +1,11 @@
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:plezy/media/media_source_info.dart';
 import 'package:plezy/media/media_version.dart';
 import 'package:plezy/widgets/video_controls/video_controls.dart';
 import 'package:plezy/widgets/video_controls/widgets/mobile_skip_zones.dart';
+import 'package:plezy/widgets/video_controls/widgets/timeline_slider.dart';
 
 void main() {
   group('effectiveVersionQualityControls', () {
@@ -67,4 +69,47 @@ void main() {
       expect(mobileSkipZoneForTap(position: const Offset(900, 580), size: size), isNull);
     });
   });
+
+  group('TimelineSlider', () {
+    testWidgets('routes keyboard input through the custom focus handler', (tester) async {
+      final focusNode = FocusNode();
+      addTearDown(focusNode.dispose);
+      var keyEvents = 0;
+      var seekEvents = 0;
+
+      await tester.pumpWidget(
+        MaterialApp(
+          home: Scaffold(
+            body: SizedBox(
+              width: 400,
+              child: TimelineSlider(
+                position: const Duration(minutes: 1),
+                duration: const Duration(minutes: 10),
+                chapters: const [],
+                chaptersLoaded: true,
+                focusNode: focusNode,
+                onKeyEvent: (_, event) {
+                  if (event is KeyDownEvent && event.logicalKey == LogicalKeyboardKey.arrowRight) {
+                    keyEvents++;
+                    return KeyEventResult.handled;
+                  }
+                  return KeyEventResult.ignored;
+                },
+                onSeek: (_) => seekEvents++,
+                onSeekEnd: (_) {},
+              ),
+            ),
+          ),
+        ),
+      );
+
+      focusNode.requestFocus();
+      await tester.pump();
+      await tester.sendKeyEvent(LogicalKeyboardKey.arrowRight);
+      await tester.pump();
+
+      expect(keyEvents, 1);
+      expect(seekEvents, 0);
+    });
+  });
 }