fix(player): preserve transcoded subtitles at high speed

close #1622

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

@@ -55,6 +55,9 @@ import androidx.media3.exoplayer.audio.AudioCapabilities
 import androidx.media3.exoplayer.audio.AudioSink
 import androidx.media3.exoplayer.mediacodec.MediaCodecSelector
 import androidx.media3.exoplayer.source.DefaultMediaSourceFactory
+import androidx.media3.exoplayer.source.FilteringMediaSource
+import androidx.media3.exoplayer.source.MediaSource
+import androidx.media3.exoplayer.source.MergingMediaSource
 import androidx.media3.exoplayer.trackselection.DefaultTrackSelector
 import androidx.media3.extractor.DefaultExtractorsFactory
 import androidx.media3.extractor.mkv.MatroskaExtractor
@@ -308,6 +311,8 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
   // External subtitles added dynamically
   private val externalSubtitles = mutableListOf<MediaItem.SubtitleConfiguration>()
   private val externalSubtitleUris = mutableListOf<String>()
+  private val externalSubtitleContainerUris = mutableListOf<String>()
+  private var playbackMediaSourceFactory: DefaultMediaSourceFactory? = null
   private var currentMediaUri: String? = null
   private var currentHeaders: Map<String, String>? = null
   private var currentMediaIsLive: Boolean = false
@@ -660,6 +665,7 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
 
       val mediaSourceFactory = DefaultMediaSourceFactory(dataSourceFactory!!, wrappedExtractorsFactory)
         .setSubtitleParserFactory(assParserFactory)
+      playbackMediaSourceFactory = mediaSourceFactory
 
       // Wrap text renderers with subtitle delay support
       val wrappedRenderersFactory = RenderersFactory { eventHandler, videoListener, audioListener, textOutput, metadataOutput ->
@@ -1215,7 +1221,7 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
         "lastOutput=${describeAudioTrackConfig(previousAudioTrackConfig)}, actions=$lastAudioRecoveryAction"
     )
 
-    player.setMediaItem(buildMediaItem(uri), savedPosition)
+    setCurrentMediaSource(player, uri, savedPosition)
     player.prepare()
     player.playWhenReady = savedPlayWhenReady
     return true
@@ -1626,6 +1632,8 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
       val isExternal = format.id?.startsWith("external_") == true
       val externalIndex = if (isExternal) format.id?.removePrefix("external_")?.toIntOrNull() else null
       val externalUri = externalIndex?.takeIf { it in externalSubtitleUris.indices }?.let { externalSubtitleUris[it] }
+      val isContainer = !isExternal && externalSubtitleContainerUris.isNotEmpty()
+      val containerUri = if (isContainer) externalSubtitleContainerUris.first() else null
 
       Log.d(TAG, "Subtitle track $groupIndex: codec=${format.codecs}, lang=${format.language}, selected=$isSelected, external=$isExternal")
 
@@ -1638,8 +1646,9 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
         "default" to (format.selectionFlags and C.SELECTION_FLAG_DEFAULT != 0),
         "forced" to (format.selectionFlags and C.SELECTION_FLAG_FORCED != 0),
         "selected" to isSelected,
-        "external" to isExternal,
-        "external-filename" to externalUri
+        "external" to (isExternal || isContainer),
+        "container" to isContainer,
+        "external-filename" to (externalUri ?: containerUri)
       )
       trackList.add(track)
 
@@ -2337,6 +2346,34 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
     return mediaItemBuilder.build()
   }
 
+  private fun buildPlaybackMediaSource(uri: String): MediaSource? {
+    val factory = playbackMediaSourceFactory ?: return null
+    val primarySource = factory.createMediaSource(buildMediaItem(uri))
+    if (externalSubtitleContainerUris.isEmpty()) return primarySource
+
+    val sources = mutableListOf<MediaSource>(primarySource)
+    externalSubtitleContainerUris.forEach { containerUri ->
+      val containerSource = factory.createMediaSource(MediaItem.fromUri(containerUri))
+      sources.add(FilteringMediaSource(containerSource, C.TRACK_TYPE_TEXT))
+    }
+    return MergingMediaSource(
+      /* adjustPeriodTimeOffsets = */
+      true,
+      /* clipDurations = */
+      false,
+      *sources.toTypedArray()
+    )
+  }
+
+  private fun setCurrentMediaSource(player: ExoPlayer, uri: String, positionMs: Long) {
+    val mediaSource = buildPlaybackMediaSource(uri)
+    if (mediaSource == null) {
+      player.setMediaItem(buildMediaItem(uri), positionMs)
+    } else {
+      player.setMediaSource(mediaSource, positionMs)
+    }
+  }
+
   private fun selectedAudioFormat(): Format? {
     val player = exoPlayer ?: return null
     val selectedAudioGroup = player.currentTracks.groups.firstOrNull {
@@ -2887,6 +2924,7 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
 
     externalSubtitles.clear()
     externalSubtitleUris.clear()
+    externalSubtitleContainerUris.clear()
     lastSubtitleCues = emptyList()
     hadSelectedTextTrack = false
     audioTrackGroupMap.clear()
@@ -2895,9 +2933,20 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
     selectedSubtitleTrackId = null
     pendingDvTrackRestore = null
 
-    // Build external subtitle configurations (attached to MediaItem before prepare)
-    externalSubtitleList?.forEachIndexed { index, sub ->
-      val subUri = sub["uri"] as? String ?: return@forEachIndexed
+    // Build external subtitle sources before prepare. Container sidecars are
+    // filtered to text tracks and merged with the primary source; standalone
+    // subtitle files continue to use MediaItem subtitle configurations.
+    externalSubtitleList?.forEach { sub ->
+      val subUri = sub["uri"] as? String ?: return@forEach
+      if (subUri.isBlank()) return@forEach
+      if (sub["isContainer"] as? Boolean == true) {
+        if (!externalSubtitleContainerUris.contains(subUri)) {
+          externalSubtitleContainerUris.add(subUri)
+        }
+        return@forEach
+      }
+
+      val index = externalSubtitles.size
       val title = sub["title"] as? String
       val language = sub["language"] as? String
       val codec = sub["codec"] as? String
@@ -2940,10 +2989,8 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
     )
     emitSeekable(false, force = true)
 
-    val mediaItem = buildMediaItem(uri)
-
     exoPlayer?.apply {
-      setMediaItem(mediaItem, startPositionMs)
+      setCurrentMediaSource(this, uri, startPositionMs)
       prepare()
       playWhenReady = autoPlay
     }
@@ -3174,8 +3221,7 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
       clearTextOverrides = true
     )
 
-    val mediaItem = buildMediaItem(uri)
-    player.setMediaItem(mediaItem, savedPosition)
+    setCurrentMediaSource(player, uri, savedPosition)
     player.prepare()
     player.playWhenReady = savedPlayWhenReady
     emitLog("info", "dv-debug", "Reloaded media for DV mode $dvMode at ${savedPosition}ms")
@@ -3317,8 +3363,7 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
         )
         selectedSubtitleTrackId = null
 
-        val mediaItem = buildMediaItem(mediaUri)
-        player.setMediaItem(mediaItem, savedPosition)
+        setCurrentMediaSource(player, mediaUri, savedPosition)
         player.prepare()
         player.playWhenReady = savedPlayWhenReady
       } else {
@@ -3748,6 +3793,7 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
     trackSelector = null
     httpDataSourceFactory = null
     dataSourceFactory = null
+    playbackMediaSourceFactory = null
     assHandler?.release()
     assHandler = null
 

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

@@ -1258,6 +1258,7 @@ class ExoPlayerPlugin :
     val escapedUris = externalSubtitles.orEmpty()
       .mapNotNull { it["uri"] as? String }
       .filter { it.isNotEmpty() }
+      .distinct()
       .map(::escapeMpvPathListEntry)
       .toList()
 

android/app/src/test/kotlin/com/edde746/plezy/exoplayer/ExoPlayerPluginTest.kt

@@ -585,6 +585,31 @@ class ExoPlayerPluginTest {
     core.dispose()
   }
 
+  @Test
+  fun mpvFallbackLoadsSharedSubtitleContainerOnce() {
+    val plugin = ExoPlayerPlugin()
+    val options = mutableListOf<String>()
+    val appendOptions = plugin.javaClass.getDeclaredMethod(
+      "appendExternalSubtitleOptions",
+      MutableList::class.java,
+      List::class.java
+    ).apply {
+      isAccessible = true
+    }
+
+    appendOptions.invoke(
+      plugin,
+      options,
+      listOf(
+        mapOf("uri" to "shared.mkv", "isContainer" to true),
+        mapOf("uri" to "shared.mkv", "isContainer" to true),
+        mapOf("uri" to "")
+      )
+    )
+
+    assertEquals(listOf("sub-files=%10%shared.mkv"), options)
+  }
+
   @Test
   fun configDetachAndEngineDetachReleaseExoActivityOwnershipExactlyOnce() {
     val activity = Robolectric.buildActivity(Activity::class.java).setup().get()

lib/mpv/models.dart

@@ -61,6 +61,7 @@ sealed class SubtitleTrack with _$SubtitleTrack {
     @Default(false) bool isDefault,
     @Default(false) bool isForced,
     @Default(false) bool isExternal,
+    @Default(false) bool isContainer,
     String? uri,
   }) = _SubtitleTrack;
 
@@ -71,6 +72,7 @@ sealed class SubtitleTrack with _$SubtitleTrack {
     String? codec,
     bool isDefault = false,
     bool isForced = false,
+    bool isContainer = false,
   }) => SubtitleTrack(
     id: 'external:$uri',
     title: title,
@@ -79,6 +81,7 @@ sealed class SubtitleTrack with _$SubtitleTrack {
     isDefault: isDefault,
     isForced: isForced,
     isExternal: true,
+    isContainer: isContainer,
     uri: uri,
   );
 

lib/mpv/models.freezed.dart

@@ -789,7 +789,7 @@ as bool,
 /// @nodoc
 mixin _$SubtitleTrack {
 
- String get id; String? get title; String? get language; String? get codec; bool get isDefault; bool get isForced; bool get isExternal; String? get uri;
+ String get id; String? get title; String? get language; String? get codec; bool get isDefault; bool get isForced; bool get isExternal; bool get isContainer; String? get uri;
 /// Create a copy of SubtitleTrack
 /// with the given fields replaced by the non-null parameter values.
 @JsonKey(includeFromJson: false, includeToJson: false)
@@ -800,16 +800,16 @@ $SubtitleTrackCopyWith<SubtitleTrack> get copyWith => _$SubtitleTrackCopyWithImp
 
 @override
 bool operator ==(Object other) {
-  return identical(this, other) || (other.runtimeType == runtimeType&&other is SubtitleTrack&&(identical(other.id, id) || other.id == id)&&(identical(other.title, title) || other.title == title)&&(identical(other.language, language) || other.language == language)&&(identical(other.codec, codec) || other.codec == codec)&&(identical(other.isDefault, isDefault) || other.isDefault == isDefault)&&(identical(other.isForced, isForced) || other.isForced == isForced)&&(identical(other.isExternal, isExternal) || other.isExternal == isExternal)&&(identical(other.uri, uri) || other.uri == uri));
+  return identical(this, other) || (other.runtimeType == runtimeType&&other is SubtitleTrack&&(identical(other.id, id) || other.id == id)&&(identical(other.title, title) || other.title == title)&&(identical(other.language, language) || other.language == language)&&(identical(other.codec, codec) || other.codec == codec)&&(identical(other.isDefault, isDefault) || other.isDefault == isDefault)&&(identical(other.isForced, isForced) || other.isForced == isForced)&&(identical(other.isExternal, isExternal) || other.isExternal == isExternal)&&(identical(other.isContainer, isContainer) || other.isContainer == isContainer)&&(identical(other.uri, uri) || other.uri == uri));
 }
 
 
 @override
-int get hashCode => Object.hash(runtimeType,id,title,language,codec,isDefault,isForced,isExternal,uri);
+int get hashCode => Object.hash(runtimeType,id,title,language,codec,isDefault,isForced,isExternal,isContainer,uri);
 
 @override
 String toString() {
-  return 'SubtitleTrack(id: $id, title: $title, language: $language, codec: $codec, isDefault: $isDefault, isForced: $isForced, isExternal: $isExternal, uri: $uri)';
+  return 'SubtitleTrack(id: $id, title: $title, language: $language, codec: $codec, isDefault: $isDefault, isForced: $isForced, isExternal: $isExternal, isContainer: $isContainer, uri: $uri)';
 }
 
 
@@ -820,7 +820,7 @@ abstract mixin class $SubtitleTrackCopyWith<$Res>  {
   factory $SubtitleTrackCopyWith(SubtitleTrack value, $Res Function(SubtitleTrack) _then) = _$SubtitleTrackCopyWithImpl;
 @useResult
 $Res call({
- String id, String? title, String? language, String? codec, bool isDefault, bool isForced, bool isExternal, String? uri
+ String id, String? title, String? language, String? codec, bool isDefault, bool isForced, bool isExternal, bool isContainer, String? uri
 });
 
 
@@ -837,7 +837,7 @@ class _$SubtitleTrackCopyWithImpl<$Res>
 
 /// Create a copy of SubtitleTrack
 /// with the given fields replaced by the non-null parameter values.
-@pragma('vm:prefer-inline') @override $Res call({Object? id = null,Object? title = freezed,Object? language = freezed,Object? codec = freezed,Object? isDefault = null,Object? isForced = null,Object? isExternal = null,Object? uri = freezed,}) {
+@pragma('vm:prefer-inline') @override $Res call({Object? id = null,Object? title = freezed,Object? language = freezed,Object? codec = freezed,Object? isDefault = null,Object? isForced = null,Object? isExternal = null,Object? isContainer = null,Object? uri = freezed,}) {
   return _then(_self.copyWith(
 id: null == id ? _self.id : id // ignore: cast_nullable_to_non_nullable
 as String,title: freezed == title ? _self.title : title // ignore: cast_nullable_to_non_nullable
@@ -846,6 +846,7 @@ as String?,codec: freezed == codec ? _self.codec : codec // ignore: cast_nullabl
 as String?,isDefault: null == isDefault ? _self.isDefault : isDefault // ignore: cast_nullable_to_non_nullable
 as bool,isForced: null == isForced ? _self.isForced : isForced // ignore: cast_nullable_to_non_nullable
 as bool,isExternal: null == isExternal ? _self.isExternal : isExternal // ignore: cast_nullable_to_non_nullable
+as bool,isContainer: null == isContainer ? _self.isContainer : isContainer // ignore: cast_nullable_to_non_nullable
 as bool,uri: freezed == uri ? _self.uri : uri // ignore: cast_nullable_to_non_nullable
 as String?,
   ));
@@ -929,10 +930,10 @@ return $default(_that);case _:
 /// }
 /// ```
 
-@optionalTypeArgs TResult maybeWhen<TResult extends Object?>(TResult Function( String id,  String? title,  String? language,  String? codec,  bool isDefault,  bool isForced,  bool isExternal,  String? uri)?  $default,{required TResult orElse(),}) {final _that = this;
+@optionalTypeArgs TResult maybeWhen<TResult extends Object?>(TResult Function( String id,  String? title,  String? language,  String? codec,  bool isDefault,  bool isForced,  bool isExternal,  bool isContainer,  String? uri)?  $default,{required TResult orElse(),}) {final _that = this;
 switch (_that) {
 case _SubtitleTrack() when $default != null:
-return $default(_that.id,_that.title,_that.language,_that.codec,_that.isDefault,_that.isForced,_that.isExternal,_that.uri);case _:
+return $default(_that.id,_that.title,_that.language,_that.codec,_that.isDefault,_that.isForced,_that.isExternal,_that.isContainer,_that.uri);case _:
   return orElse();
 
 }
@@ -950,10 +951,10 @@ return $default(_that.id,_that.title,_that.language,_that.codec,_that.isDefault,
 /// }
 /// ```
 
-@optionalTypeArgs TResult when<TResult extends Object?>(TResult Function( String id,  String? title,  String? language,  String? codec,  bool isDefault,  bool isForced,  bool isExternal,  String? uri)  $default,) {final _that = this;
+@optionalTypeArgs TResult when<TResult extends Object?>(TResult Function( String id,  String? title,  String? language,  String? codec,  bool isDefault,  bool isForced,  bool isExternal,  bool isContainer,  String? uri)  $default,) {final _that = this;
 switch (_that) {
 case _SubtitleTrack():
-return $default(_that.id,_that.title,_that.language,_that.codec,_that.isDefault,_that.isForced,_that.isExternal,_that.uri);}
+return $default(_that.id,_that.title,_that.language,_that.codec,_that.isDefault,_that.isForced,_that.isExternal,_that.isContainer,_that.uri);}
 }
 /// A variant of `when` that fallback to returning `null`
 ///
@@ -967,10 +968,10 @@ return $default(_that.id,_that.title,_that.language,_that.codec,_that.isDefault,
 /// }
 /// ```
 
-@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>(TResult? Function( String id,  String? title,  String? language,  String? codec,  bool isDefault,  bool isForced,  bool isExternal,  String? uri)?  $default,) {final _that = this;
+@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>(TResult? Function( String id,  String? title,  String? language,  String? codec,  bool isDefault,  bool isForced,  bool isExternal,  bool isContainer,  String? uri)?  $default,) {final _that = this;
 switch (_that) {
 case _SubtitleTrack() when $default != null:
-return $default(_that.id,_that.title,_that.language,_that.codec,_that.isDefault,_that.isForced,_that.isExternal,_that.uri);case _:
+return $default(_that.id,_that.title,_that.language,_that.codec,_that.isDefault,_that.isForced,_that.isExternal,_that.isContainer,_that.uri);case _:
   return null;
 
 }
@@ -982,7 +983,7 @@ return $default(_that.id,_that.title,_that.language,_that.codec,_that.isDefault,
 
 
 class _SubtitleTrack extends SubtitleTrack {
-  const _SubtitleTrack({required this.id, this.title, this.language, this.codec, this.isDefault = false, this.isForced = false, this.isExternal = false, this.uri}): super._();
+  const _SubtitleTrack({required this.id, this.title, this.language, this.codec, this.isDefault = false, this.isForced = false, this.isExternal = false, this.isContainer = false, this.uri}): super._();
   
 
 @override final  String id;
@@ -992,6 +993,7 @@ class _SubtitleTrack extends SubtitleTrack {
 @override@JsonKey() final  bool isDefault;
 @override@JsonKey() final  bool isForced;
 @override@JsonKey() final  bool isExternal;
+@override@JsonKey() final  bool isContainer;
 @override final  String? uri;
 
 /// Create a copy of SubtitleTrack
@@ -1004,16 +1006,16 @@ _$SubtitleTrackCopyWith<_SubtitleTrack> get copyWith => __$SubtitleTrackCopyWith
 
 @override
 bool operator ==(Object other) {
-  return identical(this, other) || (other.runtimeType == runtimeType&&other is _SubtitleTrack&&(identical(other.id, id) || other.id == id)&&(identical(other.title, title) || other.title == title)&&(identical(other.language, language) || other.language == language)&&(identical(other.codec, codec) || other.codec == codec)&&(identical(other.isDefault, isDefault) || other.isDefault == isDefault)&&(identical(other.isForced, isForced) || other.isForced == isForced)&&(identical(other.isExternal, isExternal) || other.isExternal == isExternal)&&(identical(other.uri, uri) || other.uri == uri));
+  return identical(this, other) || (other.runtimeType == runtimeType&&other is _SubtitleTrack&&(identical(other.id, id) || other.id == id)&&(identical(other.title, title) || other.title == title)&&(identical(other.language, language) || other.language == language)&&(identical(other.codec, codec) || other.codec == codec)&&(identical(other.isDefault, isDefault) || other.isDefault == isDefault)&&(identical(other.isForced, isForced) || other.isForced == isForced)&&(identical(other.isExternal, isExternal) || other.isExternal == isExternal)&&(identical(other.isContainer, isContainer) || other.isContainer == isContainer)&&(identical(other.uri, uri) || other.uri == uri));
 }
 
 
 @override
-int get hashCode => Object.hash(runtimeType,id,title,language,codec,isDefault,isForced,isExternal,uri);
+int get hashCode => Object.hash(runtimeType,id,title,language,codec,isDefault,isForced,isExternal,isContainer,uri);
 
 @override
 String toString() {
-  return 'SubtitleTrack(id: $id, title: $title, language: $language, codec: $codec, isDefault: $isDefault, isForced: $isForced, isExternal: $isExternal, uri: $uri)';
+  return 'SubtitleTrack(id: $id, title: $title, language: $language, codec: $codec, isDefault: $isDefault, isForced: $isForced, isExternal: $isExternal, isContainer: $isContainer, uri: $uri)';
 }
 
 
@@ -1024,7 +1026,7 @@ abstract mixin class _$SubtitleTrackCopyWith<$Res> implements $SubtitleTrackCopy
   factory _$SubtitleTrackCopyWith(_SubtitleTrack value, $Res Function(_SubtitleTrack) _then) = __$SubtitleTrackCopyWithImpl;
 @override @useResult
 $Res call({
- String id, String? title, String? language, String? codec, bool isDefault, bool isForced, bool isExternal, String? uri
+ String id, String? title, String? language, String? codec, bool isDefault, bool isForced, bool isExternal, bool isContainer, String? uri
 });
 
 
@@ -1041,7 +1043,7 @@ class __$SubtitleTrackCopyWithImpl<$Res>
 
 /// Create a copy of SubtitleTrack
 /// with the given fields replaced by the non-null parameter values.
-@override @pragma('vm:prefer-inline') $Res call({Object? id = null,Object? title = freezed,Object? language = freezed,Object? codec = freezed,Object? isDefault = null,Object? isForced = null,Object? isExternal = null,Object? uri = freezed,}) {
+@override @pragma('vm:prefer-inline') $Res call({Object? id = null,Object? title = freezed,Object? language = freezed,Object? codec = freezed,Object? isDefault = null,Object? isForced = null,Object? isExternal = null,Object? isContainer = null,Object? uri = freezed,}) {
   return _then(_SubtitleTrack(
 id: null == id ? _self.id : id // ignore: cast_nullable_to_non_nullable
 as String,title: freezed == title ? _self.title : title // ignore: cast_nullable_to_non_nullable
@@ -1050,6 +1052,7 @@ as String?,codec: freezed == codec ? _self.codec : codec // ignore: cast_nullabl
 as String?,isDefault: null == isDefault ? _self.isDefault : isDefault // ignore: cast_nullable_to_non_nullable
 as bool,isForced: null == isForced ? _self.isForced : isForced // ignore: cast_nullable_to_non_nullable
 as bool,isExternal: null == isExternal ? _self.isExternal : isExternal // ignore: cast_nullable_to_non_nullable
+as bool,isContainer: null == isContainer ? _self.isContainer : isContainer // ignore: cast_nullable_to_non_nullable
 as bool,uri: freezed == uri ? _self.uri : uri // ignore: cast_nullable_to_non_nullable
 as String?,
   ));

lib/mpv/player/platform/player_android.dart

@@ -180,7 +180,7 @@ class PlayerAndroid extends PlayerBase {
         'isLive': isLive,
         if (externalSubtitles != null && externalSubtitles.isNotEmpty)
           'externalSubtitles': externalSubtitles
-              .where((s) => s.uri != null)
+              .where((s) => s.uri?.isNotEmpty == true)
               .map(
                 (s) => {
                   'uri': s.uri,
@@ -189,6 +189,7 @@ class PlayerAndroid extends PlayerBase {
                   'codec': s.codec,
                   'isDefault': s.isDefault,
                   'isForced': s.isForced,
+                  'isContainer': s.isContainer,
                 },
               )
               .toList(),

lib/mpv/player/player_base.dart

@@ -72,7 +72,7 @@ abstract class PlayerBase with PlayerStreamControllersMixin implements Player {
   Duration? _timelineDuration;
   int _nextPropId = 0;
   final Map<int, String> _propIdToName = {};
-  Map<String, SubtitleTrack> _externalSubtitleMetadataByUri = const {};
+  Map<String, List<SubtitleTrack>> _externalSubtitleMetadataByUri = const {};
   bool _primaryMediaLoadStarted = false;
   bool _primaryMediaReadyEmitted = false;
 
@@ -499,6 +499,7 @@ abstract class PlayerBase with PlayerStreamControllersMixin implements Player {
     final subtitleTracks = <SubtitleTrack>[];
     String? selectedAudioId;
     String? selectedSubtitleId;
+    final containerMetadataIndexes = <String, int>{};
 
     for (final track in trackList) {
       if (track is! Map) continue;
@@ -511,6 +512,13 @@ abstract class PlayerBase with PlayerStreamControllersMixin implements Player {
       final selected = track['selected'] == true;
 
       if (type == 'audio') {
+        final rawExternalFilename = track['external-filename'];
+        final externalFilename = rawExternalFilename is String ? rawExternalFilename : null;
+        final externalMetadata = externalFilename == null ? null : _externalSubtitleMetadataByUri[externalFilename];
+        // Container sidecars are opened only to expose their subtitle tracks.
+        // Do not let their audio streams participate in normal track matching.
+        if (externalMetadata?.any((metadata) => metadata.isContainer) == true) continue;
+
         if (selected) selectedAudioId = id;
         audioTracks.add(
           AudioTrack(
@@ -527,20 +535,43 @@ abstract class PlayerBase with PlayerStreamControllersMixin implements Player {
         if (selected) selectedSubtitleId = id;
         final rawCodec = track['codec'];
         final codec = rawCodec is String ? rawCodec : null;
+        final rawTitle = track['title'];
+        final rawLanguage = track['lang'];
         final rawExternalFilename = track['external-filename'];
         final externalFilename = rawExternalFilename is String ? rawExternalFilename : null;
         final externalMetadata = externalFilename == null ? null : _externalSubtitleMetadataByUri[externalFilename];
-        final rawTitle = track['title'];
-        final rawLanguage = track['lang'];
+        final isContainer =
+            track['container'] == true || externalMetadata?.any((metadata) => metadata.isContainer) == true;
+        SubtitleTrack? matchedMetadata;
+        if (externalMetadata != null && externalMetadata.isNotEmpty) {
+          if (isContainer && externalFilename != null) {
+            final metadataIndex = containerMetadataIndexes[externalFilename] ?? 0;
+            containerMetadataIndexes[externalFilename] = metadataIndex + 1;
+            if (metadataIndex < externalMetadata.length && externalMetadata[metadataIndex].isContainer) {
+              matchedMetadata = externalMetadata[metadataIndex];
+            }
+          } else {
+            matchedMetadata = externalMetadata.first;
+          }
+        }
         subtitleTracks.add(
           SubtitleTrack(
             id: id,
-            title: externalMetadata?.title ?? cleanSubtitleTitle(rawTitle is String ? rawTitle : null, codec: codec),
-            language: externalMetadata?.language ?? cleanTrackMetadataValue(rawLanguage is String ? rawLanguage : null),
-            codec: externalMetadata?.codec ?? codec,
-            isDefault: externalMetadata?.isDefault ?? (track['default'] == true),
-            isForced: externalMetadata?.isForced ?? (track['forced'] == true),
+            // mpv may synthesize a container track title from the signed
+            // source filename. Source-catalog metadata is both safer and more
+            // accurate there, including on builds that drop disposition flags.
+            // Ordinary sidecars still fall back to metadata reported by mpv.
+            title: isContainer
+                ? matchedMetadata?.title
+                : matchedMetadata?.title ?? cleanSubtitleTitle(rawTitle is String ? rawTitle : null, codec: codec),
+            language: isContainer
+                ? matchedMetadata?.language
+                : matchedMetadata?.language ?? cleanTrackMetadataValue(rawLanguage is String ? rawLanguage : null),
+            codec: matchedMetadata?.codec ?? codec,
+            isDefault: matchedMetadata?.isDefault ?? (track['default'] == true),
+            isForced: matchedMetadata?.isForced ?? (track['forced'] == true),
             isExternal: track['external'] == true,
+            isContainer: isContainer,
             uri: externalFilename,
           ),
         );
@@ -599,23 +630,23 @@ abstract class PlayerBase with PlayerStreamControllersMixin implements Player {
 
   @protected
   void setExternalSubtitleMetadata(List<SubtitleTrack>? externalSubtitles) {
-    final metadataByUri = <String, SubtitleTrack>{};
+    final metadataByUri = <String, List<SubtitleTrack>>{};
     for (final subtitle in externalSubtitles ?? const <SubtitleTrack>[]) {
       final uri = subtitle.uri;
       if (uri != null && uri.isNotEmpty) {
-        metadataByUri[uri] = subtitle;
+        (metadataByUri[uri] ??= <SubtitleTrack>[]).add(subtitle);
       }
     }
     _externalSubtitleMetadataByUri = metadataByUri;
   }
 
   @protected
-  Map<String, SubtitleTrack> snapshotExternalSubtitleMetadata() =>
-      Map<String, SubtitleTrack>.of(_externalSubtitleMetadataByUri);
+  Map<String, List<SubtitleTrack>> snapshotExternalSubtitleMetadata() =>
+      Map<String, List<SubtitleTrack>>.of(_externalSubtitleMetadataByUri);
 
   @protected
-  void restoreExternalSubtitleMetadata(Map<String, SubtitleTrack> snapshot) {
-    _externalSubtitleMetadataByUri = Map<String, SubtitleTrack>.of(snapshot);
+  void restoreExternalSubtitleMetadata(Map<String, List<SubtitleTrack>> snapshot) {
+    _externalSubtitleMetadataByUri = Map<String, List<SubtitleTrack>>.of(snapshot);
   }
 
   @protected

lib/mpv/player/player_native.dart

@@ -124,6 +124,7 @@ class PlayerNative extends PlayerBase {
         ?.map((subtitle) => subtitle.uri)
         .whereType<String>()
         .where((uri) => uri.isNotEmpty)
+        .toSet()
         .map((uri) => _escapePathListEntry(uri, separator))
         .toList();
     if (escapedUris == null || escapedUris.isEmpty) return null;

lib/screens/video_player/parts/episode_navigation.dart

@@ -1,5 +1,25 @@
 part of '../../video_player_screen.dart';
 
+/// Keeps an explicit transcode subtitle choice pending while the native
+/// player finishes discovering sidecars that were attached during open.
+///
+/// Returning true tells the source-switch caller that no media reload is
+/// needed. [TrackManager] owns the generation-scoped late-track listener.
+Future<bool> deferTranscodeSubtitleSelection({
+  required TrackManager trackManager,
+  required MediaSubtitleTrack sourceTrack,
+  required PlaybackSubtitleSidecar sourceSidecar,
+  required int sourceStreamId,
+  required Future<void> Function(SubtitleTrack track, {int? sourceStreamId}) onSubtitleTrackChanged,
+  required bool Function() shouldContinue,
+}) async {
+  final deferredTrack = PlaybackSubtitleResolver.subtitleTrackForSource(sourceTrack, sidecar: sourceSidecar);
+  trackManager.preferredSubtitleTrack = deferredTrack;
+  trackManager.applyTrackSelectionWhenReady();
+  await onSubtitleTrackChanged(deferredTrack, sourceStreamId: sourceStreamId);
+  return shouldContinue();
+}
+
 extension _VideoPlayerEpisodeNavigationMethods on VideoPlayerScreenState {
   void _clearEpisodeLoadingFlags() {
     if (!_isLoadingNext && !_isLoadingPrevious) return;
@@ -198,7 +218,7 @@ extension _VideoPlayerEpisodeNavigationMethods on VideoPlayerScreenState {
 
     if (newSubtitleChoice != null && newMediaIndex == null && newPreset == null && newAudioStreamId == null) {
       try {
-        final selected = await _selectDirectPlaySourceSubtitleLocally(
+        final selected = await _selectSourceSubtitleLocally(
           currentPlayer,
           newSubtitleChoice,
           shouldContinue: isCurrentSourceSwitch,
@@ -302,12 +322,11 @@ extension _VideoPlayerEpisodeNavigationMethods on VideoPlayerScreenState {
     }
   }
 
-  Future<bool> _selectDirectPlaySourceSubtitleLocally(
+  Future<bool> _selectSourceSubtitleLocally(
     Player currentPlayer,
     PlaybackSourceSubtitleChoice choice, {
     required bool Function() shouldContinue,
   }) async {
-    if (_isTranscoding) return false;
     if (choice.isOff) {
       await currentPlayer.selectSecondarySubtitleTrack(SubtitleTrack.off);
       if (!shouldContinue()) return false;
@@ -331,15 +350,30 @@ extension _VideoPlayerEpisodeNavigationMethods on VideoPlayerScreenState {
     if (sourceTrack == null) return false;
 
     final nativeTracks = currentPlayer.state.tracks.subtitle;
-    final nativeTrack = PlaybackSubtitleResolver.nativeTrackForDirectPlaySource(
+    final session = _playbackSession;
+    final sourceSidecar = session == null ? null : _sidecarForSourceStreamId(session, sourceStreamId);
+    final nativeTrack = PlaybackSubtitleResolver.nativeTrackForSource(
       sourceTrack: sourceTrack,
       nativeTracks: nativeTracks,
       allSourceTracks: info.subtitleTracks,
-      isResolvedSidecar: _sourceSubtitleSidecarIdsForControls().contains(sourceStreamId),
-      currentSourceStreamId: _playbackSession?.subtitleSelection.primarySourceStreamId,
+      isResolvedSidecar: sourceSidecar != null,
+      isContainerSidecar: sourceSidecar?.track.isContainer == true,
+      currentSourceStreamId: session?.subtitleSelection.primarySourceStreamId,
       selectedNativeTrack: currentPlayer.state.track.subtitle,
     );
-    if (nativeTrack == null) return false;
+    if (nativeTrack == null) {
+      final trackManager = _trackManager;
+      if (!_isTranscoding || sourceSidecar == null || trackManager == null) return false;
+
+      return deferTranscodeSubtitleSelection(
+        trackManager: trackManager,
+        sourceTrack: sourceTrack,
+        sourceSidecar: sourceSidecar,
+        sourceStreamId: sourceStreamId,
+        onSubtitleTrackChanged: _onSubtitleTrackChanged,
+        shouldContinue: shouldContinue,
+      );
+    }
 
     await currentPlayer.selectSubtitleTrack(nativeTrack);
     if (!shouldContinue()) return false;
@@ -420,6 +454,7 @@ extension _VideoPlayerEpisodeNavigationMethods on VideoPlayerScreenState {
       final previousMetadata = _currentMetadata;
       final previousLaunchIdentity = VideoPlayerScreenState._activeRouteGuard.identityFor(this);
       final previousPartId = _currentMediaInfo?.partId;
+      final previousMediaSourceId = _currentMediaInfo?.mediaSourceId;
       final previousHasFirstFrame = _hasFirstFrame.value;
       final previousHasRenderedFirstFrame = _hasRenderedFirstFrame;
       final previousHasFatalPlaybackError = _hasFatalPlaybackError;
@@ -497,6 +532,13 @@ extension _VideoPlayerEpisodeNavigationMethods on VideoPlayerScreenState {
         isOffline: _offlineLibraryMode,
         routeKind: VideoPlayerRouteKind.vod,
       );
+      final preservesRequestedSubtitleSource =
+          !isItemChange &&
+          targetMediaIndex == _effectiveSelectedMediaIndex &&
+          (selectedMediaSourceId == null || selectedMediaSourceId == previousMediaSourceId);
+      final initializationSubtitleTrack = preservesRequestedSubtitleSource
+          ? currentSubtitleTrack
+          : PlaybackSubtitleResolver.preferenceWithoutSourceIdentity(currentSubtitleTrack);
       try {
         // Eager identity-only: the loading UI shows the new title immediately,
         // while the selection/source state flips with the session commit at
@@ -533,7 +575,7 @@ extension _VideoPlayerEpisodeNavigationMethods on VideoPlayerScreenState {
           offlineLibraryMode: _offlineLibraryMode,
           qualityPreset: targetQualityPreset,
           selectedAudioStreamId: targetAudioStreamId,
-          preferredSubtitleTrack: currentSubtitleTrack,
+          preferredSubtitleTrack: initializationSubtitleTrack,
           sessionIdentifier: _playbackSessionIdentifier,
           transcodeSessionId: _playbackTranscodeSessionId,
         );
@@ -553,6 +595,10 @@ extension _VideoPlayerEpisodeNavigationMethods on VideoPlayerScreenState {
           preferredAudioTrack: currentAudioTrack,
           preferredSubtitleTrack: currentSubtitleTrack,
           preferredSecondarySubtitleTrack: currentSecondarySubtitleTrack,
+          preserveSubtitleSourceIdentity:
+              result.mediaInfo != null &&
+              ((previousMediaSourceId != null && previousMediaSourceId == result.mediaInfo!.mediaSourceId) ||
+                  (previousPartId != null && previousPartId == result.mediaInfo!.partId)),
         );
         if (!isCurrentReload()) return _MediaReloadOutcome.superseded;
 

lib/screens/video_player/parts/playback_open.dart

@@ -85,6 +85,7 @@ extension _VideoPlayerOpenMethods on VideoPlayerScreenState {
     AudioTrack? preferredAudioTrack,
     SubtitleTrack? preferredSubtitleTrack,
     SubtitleTrack? preferredSecondarySubtitleTrack,
+    bool preserveSubtitleSourceIdentity = true,
   }) async {
     await _waitForProfileSettingsIfNeeded();
     if (!mounted) return const PlaybackSubtitleSelection.off();
@@ -97,6 +98,7 @@ extension _VideoPlayerOpenMethods on VideoPlayerScreenState {
       preferredAudioTrack: preferredAudioTrack,
       preferredSubtitleTrack: preferredSubtitleTrack,
       preferredSecondarySubtitleTrack: preferredSecondarySubtitleTrack,
+      preserveSourceIdentity: preserveSubtitleSourceIdentity,
     );
   }
 

lib/services/jellyfin_client/parts/playback.dart

@@ -330,24 +330,37 @@ mixin _JellyfinPlaybackMethods on MediaServerCacheMixin {
     if (preferred == null) return null;
     if (preferred.id == SubtitleTrack.off.id) return -1;
 
+    var semanticPreference = preferred;
     const sourcePrefix = 'source:';
     if (preferred.id.startsWith(sourcePrefix)) {
+      semanticPreference = SubtitleTrack(
+        id: 'navigation',
+        title: preferred.title,
+        language: preferred.language,
+        codec: preferred.codec,
+        isDefault: preferred.isDefault,
+        isForced: preferred.isForced,
+        isExternal: preferred.isExternal,
+        isContainer: preferred.isContainer,
+      );
       final explicit = int.tryParse(preferred.id.substring(sourcePrefix.length));
       if (explicit != null) {
         final exactSource = mediaInfo.subtitleTracks.where((track) => track.id == explicit).firstOrNull;
         if (exactSource != null) {
           // A source id is authoritative only within one item. When semantic
-          // metadata is available, reject a coincidentally reused episode id.
-          final exactMatch = findPlexTrackForMpvSubtitle(preferred, [exactSource]);
+          // metadata is available, prefer the best current-source row so a
+          // reused stream index cannot override a better title/codec match.
+          final semanticMatch = findPlexTrackForMpvSubtitle(semanticPreference, mediaInfo.subtitleTracks);
           final hasLanguage = preferred.language?.isNotEmpty ?? false;
-          if (!hasLanguage || (exactMatch != null && preferred.isForced == exactSource.forced)) {
+          if (!hasLanguage || (semanticMatch?.id == explicit && preferred.isForced == exactSource.forced)) {
             return explicit;
           }
+          return semanticMatch?.id;
         }
       }
     }
 
-    return findPlexTrackForMpvSubtitle(preferred, mediaInfo.subtitleTracks)?.id;
+    return findPlexTrackForMpvSubtitle(semanticPreference, mediaInfo.subtitleTracks)?.id;
   }
 
   Map<String, dynamic>? _selectNegotiatedMediaSource(Object? sources, String? selectedSourceId) {

lib/services/playback_initialization_types.dart

@@ -70,12 +70,15 @@ class PlaybackInitializationOptions {
 ///
 /// [sourceStreamId] links the playable URI back to the authoritative server
 /// subtitle catalog. It is nullable for legacy/offline files whose filename
-/// cannot be mapped to cached stream metadata.
+/// cannot be mapped to cached stream metadata. [preload] makes the sidecar
+/// available before it is selected, allowing local track switches without a
+/// media reload.
 class PlaybackSubtitleSidecar {
   final int? sourceStreamId;
   final SubtitleTrack track;
+  final bool preload;
 
-  const PlaybackSubtitleSidecar({required this.sourceStreamId, required this.track});
+  const PlaybackSubtitleSidecar({required this.sourceStreamId, required this.track, this.preload = false});
 }
 
 /// Reason the transcode branch fell back to direct play.
@@ -93,8 +96,8 @@ class PlaybackInitializationResult {
   final String? videoUrl;
   final MediaSourceInfo? mediaInfo;
 
-  /// Complete sidecar catalog for this source. Callers must resolve the active
-  /// subtitle choice and attach only the selected sidecar(s) at open time.
+  /// Complete sidecar catalog for this source. Callers resolve the active
+  /// subtitle choice and also attach sidecars marked for preloading.
   final List<PlaybackSubtitleSidecar> subtitleSidecars;
   final bool isOffline;
 

lib/services/playback_subtitle_resolver.dart

@@ -41,6 +41,7 @@ class PlaybackSubtitleSelection {
   final SubtitleTrack? secondaryTrack;
   final int? secondarySourceStreamId;
   final PlaybackSubtitleSidecar? secondarySidecar;
+  final List<PlaybackSubtitleSidecar> preloadedSidecars;
 
   const PlaybackSubtitleSelection({
     required this.primaryTrack,
@@ -49,9 +50,10 @@ class PlaybackSubtitleSelection {
     this.secondaryTrack,
     this.secondarySourceStreamId,
     this.secondarySidecar,
+    this.preloadedSidecars = const [],
   });
 
-  const PlaybackSubtitleSelection.off()
+  const PlaybackSubtitleSelection.off({this.preloadedSidecars = const []})
     : primaryTrack = SubtitleTrack.off,
       primarySourceStreamId = null,
       primarySidecar = null,
@@ -63,36 +65,72 @@ class PlaybackSubtitleSelection {
 
   List<SubtitleTrack> get sidecarsAtOpen {
     final tracks = <SubtitleTrack>[];
-    final primary = primarySidecar?.track;
-    if (primary != null) tracks.add(primary);
-    final secondary = secondarySidecar?.track;
-    if (secondary != null && secondary.uri != primary?.uri) tracks.add(secondary);
+    final added = <SubtitleTrack>{};
+    void add(SubtitleTrack? track) {
+      if (track != null && added.add(track)) tracks.add(track);
+    }
+
+    for (final sidecar in preloadedSidecars) {
+      add(sidecar.track);
+    }
+    add(primarySidecar?.track);
+    add(secondarySidecar?.track);
     return tracks;
   }
 }
 
-/// Resolves the server subtitle catalog before opening the native player, so
-/// only the active sidecar is part of the open operation.
+/// Resolves the server subtitle catalog before opening the native player,
+/// combining the active choice with any sidecars marked for preloading.
 class PlaybackSubtitleResolver {
   const PlaybackSubtitleResolver._();
 
+  /// Removes a per-source ID while retaining the semantic identity needed to
+  /// carry a subtitle choice across items or media sources.
+  static SubtitleTrack? preferenceWithoutSourceIdentity(SubtitleTrack? preferred) {
+    if (preferred == null || preferred.id == SubtitleTrack.off.id || !preferred.id.startsWith('source:')) {
+      return preferred;
+    }
+    return SubtitleTrack(
+      id: 'navigation',
+      title: preferred.title,
+      language: preferred.language,
+      codec: preferred.codec,
+      isDefault: preferred.isDefault,
+      isForced: preferred.isForced,
+      isExternal: preferred.isExternal,
+      isContainer: preferred.isContainer,
+    );
+  }
+
   static SubtitleTrack? _sourceBackedPreference(
     SubtitleTrack? preferred,
     MediaSourceInfo? mediaInfo,
-    List<_SubtitleCandidate> candidates,
-  ) {
+    List<_SubtitleCandidate> candidates, {
+    required bool preserveSourceIdentity,
+  }) {
     if (preferred == null || preferred.id == SubtitleTrack.off.id) return preferred;
 
+    var semanticPreference = preferred;
+    if (preferred.id.startsWith('source:')) {
+      if (preserveSourceIdentity) {
+        final sourceStreamId = int.tryParse(preferred.id.substring('source:'.length));
+        final exactCandidate = candidates.where((candidate) => candidate.sourceStreamId == sourceStreamId).firstOrNull;
+        if (exactCandidate != null) return exactCandidate.track;
+      } else {
+        semanticPreference = preferenceWithoutSourceIdentity(preferred)!;
+      }
+    }
+
     final sourceMatch = findPlexTrackForMpvSubtitle(
-      preferred,
+      semanticPreference,
       mediaInfo?.subtitleTracks ?? const <MediaSubtitleTrack>[],
     );
-    if (sourceMatch == null) return preferred;
+    if (sourceMatch == null) return semanticPreference;
 
     for (final candidate in candidates) {
       if (candidate.sourceStreamId == sourceMatch.id) return candidate.track;
     }
-    return preferred;
+    return semanticPreference;
   }
 
   static PlaybackSubtitleSelection resolve({
@@ -103,6 +141,7 @@ class PlaybackSubtitleResolver {
     AudioTrack? preferredAudioTrack,
     SubtitleTrack? preferredSubtitleTrack,
     SubtitleTrack? preferredSecondarySubtitleTrack,
+    bool preserveSourceIdentity = true,
   }) {
     final candidates = <_SubtitleCandidate>[];
     final matchedSidecars = <PlaybackSubtitleSidecar>{};
@@ -128,6 +167,7 @@ class PlaybackSubtitleResolver {
       );
     }
 
+    final preloadedSidecars = sidecars.where((sidecar) => sidecar.preload).toList(growable: false);
     final availableTracks = candidates.map((candidate) => candidate.track).toList(growable: false);
     final service = TrackSelectionService(
       profileSettings: profileSettings,
@@ -135,16 +175,30 @@ class PlaybackSubtitleResolver {
       plexMediaInfo: mediaInfo,
     );
     final selectedAudio = service.selectAudioTrack(_audioTracksForSource(mediaInfo), preferredAudioTrack)?.track;
-    final primaryPreference = _sourceBackedPreference(preferredSubtitleTrack, mediaInfo, candidates);
+    final primaryPreference = _sourceBackedPreference(
+      preferredSubtitleTrack,
+      mediaInfo,
+      candidates,
+      preserveSourceIdentity: preserveSourceIdentity,
+    );
     final primaryResult = service.selectSubtitleTrack(availableTracks, primaryPreference, selectedAudio);
-    final primary = primaryResult.track;
-    if (primary.id == SubtitleTrack.off.id) return const PlaybackSubtitleSelection.off();
+    final primary = primaryResult?.track;
+    if (primary == null || primary.id == SubtitleTrack.off.id) {
+      return PlaybackSubtitleSelection.off(preloadedSidecars: preloadedSidecars);
+    }
 
     final primaryCandidate = candidates.where((candidate) => candidate.track.id == primary.id).firstOrNull;
-    if (primaryCandidate == null) return const PlaybackSubtitleSelection.off();
+    if (primaryCandidate == null) {
+      return PlaybackSubtitleSelection.off(preloadedSidecars: preloadedSidecars);
+    }
 
     _SubtitleCandidate? secondaryCandidate;
-    final secondaryPreference = _sourceBackedPreference(preferredSecondarySubtitleTrack, mediaInfo, candidates);
+    final secondaryPreference = _sourceBackedPreference(
+      preferredSecondarySubtitleTrack,
+      mediaInfo,
+      candidates,
+      preserveSourceIdentity: preserveSourceIdentity,
+    );
     if (secondaryPreference != null && secondaryPreference.id != SubtitleTrack.off.id) {
       final secondary = service.findBestSubtitleMatch(availableTracks, secondaryPreference);
       secondaryCandidate = candidates
@@ -159,6 +213,7 @@ class PlaybackSubtitleResolver {
       secondaryTrack: secondaryCandidate?.track,
       secondarySourceStreamId: secondaryCandidate?.sourceStreamId,
       secondarySidecar: secondaryCandidate?.sidecar,
+      preloadedSidecars: preloadedSidecars,
     );
   }
 
@@ -180,26 +235,29 @@ class PlaybackSubtitleResolver {
       isDefault: sourceTrack.selected,
       isForced: sourceTrack.forced,
       isExternal: playable != null,
+      isContainer: playable?.isContainer ?? false,
       uri: playable?.uri,
     );
   }
 
-  /// Resolve a server source row to a track already loaded by direct play.
-  /// Resolved sidecars only match by their stable URL key (or the current
-  /// source identity); fuzzy language/codec matching must not select a
-  /// different sidecar that happens to have similar metadata. A server's
-  /// `external delivery` flag is not sufficient to classify a direct-play
-  /// row as a sidecar: Jellyfin applies it to embedded tracks that mpv still
-  /// discovers in the original file.
-  static SubtitleTrack? nativeTrackForDirectPlaySource({
+  /// Resolve a server source row to a track already loaded by the player.
+  /// Standalone sidecars match only by their stable URL key (or current source
+  /// identity), while a container sidecar uses normal Plex/native metadata
+  /// matching across the subtitle tracks extracted from that container.
+  static SubtitleTrack? nativeTrackForSource({
     required MediaSubtitleTrack sourceTrack,
     required List<SubtitleTrack> nativeTracks,
     required List<MediaSubtitleTrack> allSourceTracks,
     required bool isResolvedSidecar,
+    required bool isContainerSidecar,
     int? currentSourceStreamId,
     SubtitleTrack? selectedNativeTrack,
   }) {
     if (isResolvedSidecar) {
+      if (isContainerSidecar) {
+        final containerTracks = nativeTracks.where((track) => track.isContainer).toList(growable: false);
+        return findMpvTrackForPlexSubtitle(sourceTrack, containerTracks, allPlexTracks: allSourceTracks);
+      }
       final key = sourceTrack.key;
       if (key != null && key.isNotEmpty) {
         for (final candidate in nativeTracks) {

lib/services/plex_client.dart

@@ -77,7 +77,6 @@ import 'plex_lyrics_parser.dart';
 import 'plex_mappers.dart';
 import 'plex_playback_mapper.dart';
 import 'playback_initialization_types.dart';
-import 'track_selection_service.dart';
 
 part 'plex_client/parts/live_tv.dart';
 part 'plex_client/parts/playlists.dart';
@@ -2437,9 +2436,9 @@ class PlexClient
 
   /// Build an HLS VOD transcode stream URL (decision + start path).
   ///
-  /// Text subtitles selected on the Plex part are segmented as WebVTT,
-  /// image subtitles are burned because HLS has no bitmap subtitle rendition,
-  /// and real external sidecars are still attached separately by callers.
+  /// Subtitle delivery stays outside the HLS video stream. Callers attach
+  /// Plex subtitle sources independently, so changing subtitle tracks never
+  /// restarts the video transcode.
   ///
   /// [transcodeSessionId] and [sessionIdentifier] should be reused across
   /// seeks + quality/version/audio switches within one playback so the
@@ -2452,7 +2451,6 @@ class PlexClient
     required String sessionIdentifier,
     required String transcodeSessionId,
     int? audioStreamId,
-    MediaSubtitleTrack? selectedSubtitleTrack,
   }) async {
     try {
       final allParams = _buildTranscodeParams(
@@ -2463,7 +2461,6 @@ class PlexClient
         sessionIdentifier: sessionIdentifier,
         transcodeSessionId: transcodeSessionId,
         audioStreamId: audioStreamId,
-        selectedSubtitleTrack: selectedSubtitleTrack,
       );
       return await _runTranscodeDecision(
         startEndpoint: _plexVideoHlsStartEndpoint,
@@ -2521,17 +2518,13 @@ class PlexClient
     required Map<String, String> allParams,
     required bool isOriginal,
   }) async {
-    final queryString = allParams.entries.map((e) => '${_plexEncode(e.key)}=${_plexEncode(e.value)}').join('&');
     final decisionEndpoint = '${startEndpoint.substring(0, startEndpoint.lastIndexOf('/'))}/decision';
 
-    final decisionClient = MediaServerHttpClient(
-      connectTimeout: MediaServerTimeouts.connect,
-      receiveTimeout: MediaServerTimeouts.receive,
-      defaultHeaders: const {'Accept-Language': 'en', 'Accept': 'application/json'},
+    final decisionResponse = await _http.get(
+      decisionEndpoint,
+      queryParameters: allParams,
+      headers: const {'Accept-Language': 'en', 'Accept': 'application/json'},
     );
-    try {
-      final decisionUrl = '${config.baseUrl}$decisionEndpoint?$queryString';
-      final decisionResponse = await decisionClient.get(decisionUrl);
 
     final decisionBody = decisionResponse.data?.toString() ?? '<empty>';
     appLogger.i(
@@ -2550,9 +2543,6 @@ class PlexClient
     }
 
     return (startPath: _buildTranscodeStartPathFromParams(allParams, endpoint: startEndpoint), outcome: outcome);
-    } finally {
-      decisionClient.close();
-    }
   }
 
   String _buildTranscodeStartPathFromParams(
@@ -2580,13 +2570,8 @@ class PlexClient
     required String sessionIdentifier,
     required String transcodeSessionId,
     int? audioStreamId,
-    MediaSubtitleTrack? selectedSubtitleTrack,
   }) {
     final isOriginal = preset.isOriginal;
-    final selectedInternalSubtitle = _selectedInternalSubtitleForHls(selectedSubtitleTrack);
-    final segmentSubtitle = selectedInternalSubtitle != null && _canTranscodeSubtitleAsText(selectedInternalSubtitle);
-    final burnSubtitle =
-        selectedInternalSubtitle != null && CodecUtils.isImageSubtitleCodec(selectedInternalSubtitle.codec);
     final clientProfileExtra = _buildPlexHlsClientProfileExtra(
       maxVideoBitrateKbps: !isOriginal ? preset.videoBitrateKbps : null,
     );
@@ -2609,13 +2594,7 @@ class PlexClient
       'directStreamAudio': '0',
       'mediaBufferSize': '102400',
       'session': transcodeSessionId,
-      'subtitles': segmentSubtitle
-          ? 'segmented'
-          : burnSubtitle
-          ? 'burn'
-          : 'none',
-      if (selectedInternalSubtitle != null) 'subtitleStreamID': selectedInternalSubtitle.id.toString(),
-      if (segmentSubtitle) 'advancedSubtitles': 'text',
+      'subtitles': 'none',
       if (audioStreamId != null) 'audioStreamID': audioStreamId.toString(),
       'Accept-Language': 'en',
       'X-Plex-Session-Identifier': sessionIdentifier,
@@ -2644,7 +2623,6 @@ class PlexClient
     required String sessionIdentifier,
     required String transcodeSessionId,
     int? audioStreamId,
-    MediaSubtitleTrack? selectedSubtitleTrack,
   }) {
     return _buildTranscodeParams(
       ratingKey: ratingKey,
@@ -2654,7 +2632,6 @@ class PlexClient
       sessionIdentifier: sessionIdentifier,
       transcodeSessionId: transcodeSessionId,
       audioStreamId: audioStreamId,
-      selectedSubtitleTrack: selectedSubtitleTrack,
     );
   }
 
@@ -3084,9 +3061,8 @@ class PlexClient
 
   /// Plex playback resolution. Reuses [getVideoPlaybackData] for metadata,
   /// then either runs the transcode-decision flow or returns the direct-play
-  /// URL. Keyed subtitle tracks remain external sidecars; selected internal
-  /// text tracks become segmented WebVTT and image tracks are burned into the
-  /// HLS rendition.
+  /// URL. Transcoded video stays subtitle-free; every Plex subtitle remains
+  /// independently selectable through the returned sidecar catalog.
   @override
   Future<PlaybackInitializationResult> getPlaybackInitialization(PlaybackInitializationOptions options) async {
     try {
@@ -3135,7 +3111,6 @@ class PlexClient
         }
 
         final resolvedAudioId = _resolveAudioStreamId(options.selectedAudioStreamId, data.mediaInfo);
-        final selectedSubtitleTrack = _resolveTranscodeSubtitleTrack(data.mediaInfo, options.preferredSubtitleTrack);
         final result = await buildTranscodeStartPath(
           ratingKey: options.metadata.id,
           mediaIndex: data.selectedMediaIndex,
@@ -3144,12 +3119,11 @@ class PlexClient
           sessionIdentifier: options.sessionIdentifier!,
           transcodeSessionId: options.transcodeSessionId!,
           audioStreamId: resolvedAudioId,
-          selectedSubtitleTrack: selectedSubtitleTrack,
         );
 
         if (result.outcome == TranscodeDecisionOutcome.transcodeOk && result.startPath != null) {
           final transcodeUrl = '${config.baseUrl}${result.startPath}'.withPlexToken(config.token);
-          final subtitleSidecars = _buildTranscodeSidecarSubtitles(data.mediaInfo);
+          final subtitleSidecars = _buildTranscodeSidecarSubtitles(data.mediaInfo, data.videoUrl!);
           return PlaybackInitializationResult(
             availableVersions: data.availableVersions,
             videoUrl: transcodeUrl,
@@ -3249,41 +3223,6 @@ class PlexClient
     return tracks.first.id;
   }
 
-  MediaSubtitleTrack? _selectedSubtitleTrack(MediaSourceInfo? info) {
-    if (info == null) return null;
-    for (final track in info.subtitleTracks) {
-      if (track.selected) return track;
-    }
-    return null;
-  }
-
-  MediaSubtitleTrack? _resolveTranscodeSubtitleTrack(MediaSourceInfo? info, SubtitleTrack? preferred) {
-    if (info == null) return null;
-    if (preferred == null) return _selectedSubtitleTrack(info);
-    if (preferred.id == SubtitleTrack.off.id) return null;
-
-    MediaSubtitleTrack? matched;
-    if (preferred.id.startsWith('source:')) {
-      final sourceId = int.tryParse(preferred.id.substring('source:'.length));
-      if (sourceId != null) {
-        for (final track in info.subtitleTracks) {
-          if (track.id == sourceId) {
-            matched = track;
-            break;
-          }
-        }
-      }
-    }
-
-    matched ??= findPlexTrackForMpvSubtitle(preferred, info.subtitleTracks);
-    return matched ?? _selectedSubtitleTrack(info);
-  }
-
-  @visibleForTesting
-  MediaSubtitleTrack? resolveTranscodeSubtitleTrackForTesting(MediaSourceInfo? info, SubtitleTrack? preferred) {
-    return _resolveTranscodeSubtitleTrack(info, preferred);
-  }
-
   /// Build the absolute URL for an external subtitle track on this Plex
   /// server. Returns `null` for tracks that aren't external (no `/library/
   /// streams/{id}` key) or when the server has no auth token.
@@ -3305,20 +3244,10 @@ class PlexClient
   /// `Stream.key` is required here.
   String? _buildSidecarSubtitleUrl(MediaSubtitleTrack track) {
     if (track.key == null || track.key!.isEmpty) return null;
-    final token = config.token;
-    if (token == null) return null;
     final ext = CodecUtils.getSubtitleExtension(track.codec);
-    return '${config.baseUrl}${track.key}.$ext?encoding=utf-8&X-Plex-Token=$token';
-  }
-
-  bool _canTranscodeSubtitleAsText(MediaSubtitleTrack track) {
-    return CodecUtils.isTextSubtitleCodec(track.codec);
-  }
-
-  MediaSubtitleTrack? _selectedInternalSubtitleForHls(MediaSubtitleTrack? track) {
-    if (track == null) return null;
-    if (track.key != null && track.key!.isNotEmpty) return null;
-    return CodecUtils.isTranscodableSubtitleCodec(track.codec) ? track : null;
+    final url = '${config.baseUrl}${track.key}.$ext?encoding=utf-8';
+    final token = config.token;
+    return token == null ? url : '$url&X-Plex-Token=$token';
   }
 
   SubtitleTrack _subtitleTrackFromMediaTrack(MediaSubtitleTrack track, String url) {
@@ -3334,21 +3263,42 @@ class PlexClient
     );
   }
 
-  /// Build subtitle sidecars for Plex transcode playback. Keyed tracks remain
-  /// external; the selected internal track is delivered by the HLS rendition.
-  List<PlaybackSubtitleSidecar> _buildTranscodeSidecarSubtitles(MediaSourceInfo? mediaInfo) {
-    if (mediaInfo == null) return const [];
-    if (config.token == null) {
-      appLogger.w('No auth token available for transcode sidecar subtitles');
-      return const [];
+  SubtitleTrack _containerSubtitleTrackFromMediaTrack(MediaSubtitleTrack track, String url) {
+    return SubtitleTrack(
+      id: 'container:${track.id}',
+      title: track.displayTitle ?? track.title ?? track.language ?? 'Track ${track.id}',
+      language: track.languageCode,
+      codec: track.codec,
+      isDefault: track.selected,
+      isForced: track.forced,
+      isExternal: true,
+      isContainer: true,
+      uri: url,
+    );
   }
 
+  /// Build the complete subtitle catalog for Plex transcode playback.
+  ///
+  /// Real sidecar files keep their direct stream URL. Embedded subtitle
+  /// streams share the original media container as a subtitle-only source;
+  /// player backends filter that source to text tracks. Every entry is
+  /// preloaded so changing subtitles is a local track selection.
+  List<PlaybackSubtitleSidecar> _buildTranscodeSidecarSubtitles(MediaSourceInfo? mediaInfo, String sourceUrl) {
+    if (mediaInfo == null) return const [];
+
     final tracks = <PlaybackSubtitleSidecar>[];
     for (final sub in mediaInfo.subtitleTracks) {
       try {
-        final url = _buildSidecarSubtitleUrl(sub);
-        if (url == null) continue;
-        tracks.add(PlaybackSubtitleSidecar(sourceStreamId: sub.id, track: _subtitleTrackFromMediaTrack(sub, url)));
+        final directUrl = _buildSidecarSubtitleUrl(sub);
+        tracks.add(
+          PlaybackSubtitleSidecar(
+            sourceStreamId: sub.id,
+            track: directUrl == null
+                ? _containerSubtitleTrackFromMediaTrack(sub, sourceUrl)
+                : _subtitleTrackFromMediaTrack(sub, directUrl),
+            preload: true,
+          ),
+        );
       } catch (e) {
         appLogger.w('Failed to build sidecar subtitle for stream ${sub.id}', error: e);
       }
@@ -3357,8 +3307,8 @@ class PlexClient
   }
 
   @visibleForTesting
-  List<SubtitleTrack> buildTranscodeSidecarSubtitlesForTesting(MediaSourceInfo? mediaInfo) {
-    return _buildTranscodeSidecarSubtitles(mediaInfo).map((sidecar) => sidecar.track).toList(growable: false);
+  List<PlaybackSubtitleSidecar> buildTranscodeSidecarSubtitlesForTesting(MediaSourceInfo? mediaInfo, String sourceUrl) {
+    return _buildTranscodeSidecarSubtitles(mediaInfo, sourceUrl);
   }
 
   /// Build list of external subtitle tracks from media info

lib/services/track_manager.dart

@@ -56,7 +56,6 @@ class TrackManager {
   bool waitingForExternalSubsTrackSelection = false;
   bool _externalSubtitleAddsInFlight = false;
   bool _isApplyingTrackSelection = false;
-  int? _applyingSelectionGeneration;
   Completer<void>? _selectionIdleCompleter;
   Future<void>? _activePlayerMutationDrain;
   List<SubtitleTrack> _lastExternalSubtitles = const [];
@@ -199,31 +198,61 @@ class TrackManager {
   // ── Track selection ────────────────────────────────────────────────
 
   /// Apply track selection once tracks are available.
-  /// If tracks are not yet loaded, subscribes to the stream.
+  ///
+  /// The five-second fallback applies any ready audio/rate settings, but a
+  /// source that advertises subtitles keeps listening for their late native
+  /// track-list update. The listener has a separate hard deadline and every
+  /// callback is scoped to the current media generation.
   void applyTrackSelectionWhenReady() {
+    final selectionGeneration = _selectionGeneration;
+    bool selectionIsCurrent() => _isSelectionCurrent(selectionGeneration);
     final currentTracks = player.state.tracks;
     if (_tracksReadyForSelection(currentTracks)) {
-      applyTrackSelection();
-    } else {
+      unawaited(applyTrackSelection());
+      return;
+    }
+
     _trackLoadingSubscription?.cancel();
     _trackLoadingSubscription = player.streams.tracks.listen((tracks) {
-        if (!_tracksReadyForSelection(tracks)) return;
+      if (!selectionIsCurrent() || !_tracksReadyForSelection(tracks)) return;
 
       _trackLoadingSubscription?.cancel();
       _trackLoadingSubscription = null;
       _trackSelectionFallbackTimer?.cancel();
       _trackSelectionFallbackTimer = null;
-        applyTrackSelection();
+      unawaited(applyTrackSelection());
     });
 
     _trackSelectionFallbackTimer?.cancel();
     _trackSelectionFallbackTimer = Timer(const Duration(seconds: 5), () {
-        if (!isActive()) return;
+      if (!selectionIsCurrent()) return;
+
+      final tracks = player.state.tracks;
+      final waitingForAdvertisedSubtitles =
+          mediaInfo?.subtitleTracks.isNotEmpty == true && !_tracksReadyForSelection(tracks);
+      if (!waitingForAdvertisedSubtitles) {
         _trackLoadingSubscription?.cancel();
         _trackLoadingSubscription = null;
-        applyTrackSelection();
-      });
+        _trackSelectionFallbackTimer = null;
+        unawaited(applyTrackSelection());
+        return;
       }
+
+      appLogger.w(
+        'Native subtitle tracks are still pending after 5 seconds; applying ready track settings and continuing to wait',
+      );
+      unawaited(applyTrackSelection());
+      _trackSelectionFallbackTimer = Timer(const Duration(seconds: 25), () {
+        if (!selectionIsCurrent()) return;
+        _trackLoadingSubscription?.cancel();
+        _trackLoadingSubscription = null;
+        _trackSelectionFallbackTimer = null;
+        if (!_tracksReadyForSelection(player.state.tracks)) {
+          appLogger.w('Advertised native subtitle selection did not resolve before the 30-second deadline');
+        }
+        unawaited(applyTrackSelection());
+      });
+    });
   }
 
   bool _tracksReadyForSelection(Tracks tracks) {
@@ -231,14 +260,29 @@ class TrackManager {
     if (!hasAnyTracks) return false;
 
     final info = mediaInfo;
-    if (info == null || tracks.subtitle.isNotEmpty) return true;
+    if (info == null || info.subtitleTracks.isEmpty) return true;
+    if (tracks.subtitle.isEmpty) return false;
 
-    // Plex can legitimately report subtitles without selecting one. During an
-    // in-place item reload Android clears the old track list before the new
-    // demuxed subtitles arrive; applying selection at the first audio-only
-    // update would treat that temporary empty subtitle list as an explicit
-    // server "off" decision and leave the next episode without selectable subs.
-    return info.subtitleTracks.isEmpty;
+    final nativeSubtitleTracks = tracks.subtitle
+        .where((track) => track.id != SubtitleTrack.auto.id && track.id != SubtitleTrack.off.id)
+        .toList(growable: false);
+    final preferred = preferredSubtitleTrack;
+    final preferredHasSemanticIdentity =
+        preferred != null &&
+        preferred.id != SubtitleTrack.off.id &&
+        (preferred.id.startsWith('source:') ||
+            preferred.uri != null ||
+            preferred.title != null ||
+            preferred.language != null);
+    if (preferredHasSemanticIdentity) {
+      final service = TrackSelectionService(metadata: metadata, plexMediaInfo: info);
+      return service.findBestSubtitleMatch(nativeSubtitleTracks, preferred) != null;
+    }
+
+    final serverSelectedTrack = info.subtitleTracks.where((track) => track.selected).firstOrNull;
+    if (serverSelectedTrack == null) return true;
+    return findMpvTrackForPlexSubtitle(serverSelectedTrack, nativeSubtitleTracks, allPlexTracks: info.subtitleTracks) !=
+        null;
   }
 
   /// Core track selection: delegates to [TrackSelectionService]. Returns
@@ -249,10 +293,10 @@ class TrackManager {
     if (!selectionIsActive()) return false;
 
     if (_isApplyingTrackSelection) {
-      // Calls from the active generation are already represented by the
-      // in-flight selection. A replacement generation, however, must wait for
-      // stale work to unwind rather than losing its only selection request.
-      if (_applyingSelectionGeneration == selectionGeneration) return false;
+      // A later track-list event can make a same-generation selection materially
+      // different (notably when subtitles arrive while the five-second audio/rate
+      // fallback is still applying). Queue one pass after the current mutation
+      // chain rather than dropping that event.
       final activeSelectionDone = _selectionIdleCompleter?.future;
       if (activeSelectionDone == null) return false;
       await activeSelectionDone;
@@ -261,7 +305,6 @@ class TrackManager {
     }
 
     _isApplyingTrackSelection = true;
-    _applyingSelectionGeneration = selectionGeneration;
     final idleCompleter = Completer<void>();
     _selectionIdleCompleter = idleCompleter;
     try {
@@ -294,7 +337,6 @@ class TrackManager {
       return false;
     } finally {
       _isApplyingTrackSelection = false;
-      _applyingSelectionGeneration = null;
       if (identical(_selectionIdleCompleter, idleCompleter)) {
         _selectionIdleCompleter = null;
         idleCompleter.complete();

lib/services/track_selection_service.dart

@@ -85,46 +85,62 @@ SubtitleTrack? findMpvTrackForPlexSubtitle(
   List<MediaSubtitleTrack>? allPlexTracks,
 }) {
   if (mpvTracks.isEmpty) return null;
+  final sourceId = int.tryParse(plexTrack.id.toString());
+  if (sourceId != null) {
+    final exactSourceTrack = mpvTracks.where((track) => track.id == 'source:$sourceId').firstOrNull;
+    if (exactSourceTrack != null) return exactSourceTrack;
+  }
 
-  // For external subtitles, match by URI containing the Plex key
-  if (plexTrack.isExternal && plexTrack.key != null) {
+  // Keyed subtitles have a stable identity. Do not let a sidecar that has not
+  // arrived yet fall through to fuzzy language/title scoring.
+  final plexKey = plexTrack.key;
+  if (plexKey != null && plexKey.isNotEmpty) {
     for (final mpvTrack in mpvTracks) {
-      if (mpvTrack.isExternal && mpvTrack.uri != null) {
-        // Check if the MPV URI contains the Plex key path
-        if (mpvTrack.uri!.contains(plexTrack.key!)) {
+      if (mpvTrack.isExternal && mpvTrack.uri?.contains(plexKey) == true) {
         return mpvTrack;
       }
     }
-    }
+    return null;
   }
 
   // For internal subtitles, use scoring based on properties
   SubtitleTrack? bestMatch;
   int bestScore = 0;
+  bool bestMatchUsesContainerOrdinal = false;
 
-  // Ordinal tiebreaker: precompute position of plexTrack among internal tracks
-  final internalMpvTracks = allPlexTracks != null ? mpvTracks.where((t) => !t.isExternal).toList() : null;
-  final plexOrdinal = allPlexTracks != null
-      ? allPlexTracks.where((t) => !t.isExternal).toList().indexOf(plexTrack)
-      : -1;
+  // Ordinal identity: container sidecars expose embedded subtitle tracks as
+  // external media, but retain the source container's subtitle ordering.
+  final containerPlexTracks = allPlexTracks
+      ?.where((track) => track.key == null || track.key!.isEmpty)
+      .toList(growable: false);
+  final internalMpvTracks = allPlexTracks == null
+      ? null
+      : mpvTracks.where((track) => !track.isExternal || track.isContainer).toList(growable: false);
+  final plexOrdinal = containerPlexTracks?.indexOf(plexTrack) ?? -1;
 
   for (final mpvTrack in mpvTracks) {
-    // Skip external tracks when matching internal Plex tracks
-    if (!plexTrack.isExternal && mpvTrack.isExternal) continue;
+    // A container sidecar's subtitle tracks map to internal Plex streams.
+    if (!plexTrack.isExternal && mpvTrack.isExternal && !mpvTrack.isContainer) continue;
 
     final ordinalMatches =
         internalMpvTracks != null && plexOrdinal >= 0 && internalMpvTracks.indexOf(mpvTrack) == plexOrdinal;
 
+    // A container track has no stable native ID. Its source-container ordinal
+    // is authoritative; a metadata-identical earlier track is not a match.
+    if (mpvTrack.isContainer && plexOrdinal >= 0 && !ordinalMatches) continue;
+
     final score = _scoreSubtitleMatch(mpvTrack, plexTrack, ordinalMatches: ordinalMatches);
 
     if (score > bestScore) {
       bestScore = score;
       bestMatch = mpvTrack;
+      bestMatchUsesContainerOrdinal = mpvTrack.isContainer && ordinalMatches;
     }
   }
 
-  // Require at least language match for a valid match
-  return bestScore >= 10 ? bestMatch : null;
+  // Prefer metadata matches. Container sidecars may expose no language/title/
+  // codec at all, so their stable subtitle order is the last-resort identity.
+  return bestScore >= 10 || bestMatchUsesContainerOrdinal ? bestMatch : null;
 }
 
 /// Find the Plex subtitle track that matches an MPV subtitle track
@@ -134,43 +150,61 @@ MediaSubtitleTrack? findPlexTrackForMpvSubtitle(
   List<SubtitleTrack>? allMpvTracks,
 }) {
   if (plexTracks.isEmpty) return null;
+  if (mpvTrack.id.startsWith('source:')) {
+    final sourceId = int.tryParse(mpvTrack.id.substring('source:'.length));
+    if (sourceId != null) {
+      final exactSourceTrack = plexTracks.where((track) => track.id == sourceId).firstOrNull;
+      if (exactSourceTrack != null) return exactSourceTrack;
+    }
+  }
 
-  // For external subtitles, match by URI containing the Plex key
+  // A standalone keyed subtitle maps back only by its stable Plex key.
+  // Container sidecars may continue to the source-container matcher below.
   if (mpvTrack.isExternal && mpvTrack.uri != null) {
     for (final plexTrack in plexTracks) {
-      if (plexTrack.isExternal && plexTrack.key != null) {
-        if (mpvTrack.uri!.contains(plexTrack.key!)) {
+      final plexKey = plexTrack.key;
+      if (plexKey != null && plexKey.isNotEmpty && mpvTrack.uri!.contains(plexKey)) {
         return plexTrack;
       }
     }
-    }
+    if (!mpvTrack.isContainer) return null;
   }
 
   // For internal subtitles, use scoring based on properties
   MediaSubtitleTrack? bestMatch;
   int bestScore = 0;
+  bool bestMatchUsesContainerOrdinal = false;
 
-  // Ordinal tiebreaker: precompute position of mpvTrack among internal tracks
-  final internalPlexTracks = allMpvTracks != null ? plexTracks.where((t) => !t.isExternal).toList() : null;
-  final mpvOrdinal = allMpvTracks != null ? allMpvTracks.where((t) => !t.isExternal).toList().indexOf(mpvTrack) : -1;
+  // Ordinal identity: container-sidecar tracks map back to source-container
+  // streams even though the native player marks their source as external.
+  final mpvIsInternal = !mpvTrack.isExternal || mpvTrack.isContainer;
+  final containerPlexTracks = allMpvTracks == null
+      ? null
+      : plexTracks.where((track) => track.key == null || track.key!.isEmpty).toList(growable: false);
+  final mpvOrdinal = allMpvTracks == null
+      ? -1
+      : allMpvTracks.where((track) => !track.isExternal || track.isContainer).toList().indexOf(mpvTrack);
 
   for (final plexTrack in plexTracks) {
-    // Skip external Plex tracks when matching internal MPV tracks
-    if (!mpvTrack.isExternal && plexTrack.isExternal) continue;
+    if (mpvIsInternal && plexTrack.isExternal) continue;
 
     final ordinalMatches =
-        internalPlexTracks != null && mpvOrdinal >= 0 && internalPlexTracks.indexOf(plexTrack) == mpvOrdinal;
+        containerPlexTracks != null && mpvOrdinal >= 0 && containerPlexTracks.indexOf(plexTrack) == mpvOrdinal;
+
+    if (mpvTrack.isContainer && containerPlexTracks != null && !ordinalMatches) continue;
 
     final score = _scoreSubtitleMatch(mpvTrack, plexTrack, ordinalMatches: ordinalMatches);
 
     if (score > bestScore) {
       bestScore = score;
       bestMatch = plexTrack;
+      bestMatchUsesContainerOrdinal = mpvTrack.isContainer && ordinalMatches;
     }
   }
 
-  // Require at least language match for a valid match
-  return bestScore >= 10 ? bestMatch : null;
+  // Prefer metadata matches, with container order as the symmetric fallback
+  // needed to persist a metadata-free native track back to its Plex stream.
+  return bestScore >= 10 || bestMatchUsesContainerOrdinal ? bestMatch : null;
 }
 
 /// Find the MPV audio track that matches a Plex audio track
@@ -568,11 +602,19 @@ class TrackSelectionService {
       return SubtitleTrack.off;
     }
 
+    if (preferred.id.startsWith('source:')) {
+      final sourceId = int.tryParse(preferred.id.substring('source:'.length));
+      final sourceTrack = sourceId == null
+          ? null
+          : plexMediaInfo?.subtitleTracks.where((track) => track.id == sourceId).firstOrNull;
+      if (sourceTrack == null) return null;
+      return findMpvTrackForPlexSubtitle(sourceTrack, availableTracks, allPlexTracks: plexMediaInfo?.subtitleTracks);
+    }
+
     final preferredUri = preferred.uri;
     if (preferredUri != null) {
-      for (final track in availableTracks) {
-        if (track.uri == preferredUri) return track;
-      }
+      final uriMatches = availableTracks.where((track) => track.uri == preferredUri).toList(growable: false);
+      if (uriMatches.length == 1) return uriMatches.single;
     }
 
     return findBestTrackMatch<SubtitleTrack>(
@@ -720,7 +762,11 @@ class TrackSelectionService {
   /// Priority 3: User profile subtitle mode
   /// Priority 4: Default track
   /// Priority 5: Off
-  TrackSelectionResult<SubtitleTrack> selectSubtitleTrack(
+  ///
+  /// Returns null while the source catalog advertises subtitles but the
+  /// native player has not exposed any of them yet. That transient state is
+  /// not equivalent to an explicit server decision to turn subtitles off.
+  TrackSelectionResult<SubtitleTrack>? selectSubtitleTrack(
     List<SubtitleTrack> availableTracks,
     SubtitleTrack? preferredSubtitleTrack,
     AudioTrack? selectedAudioTrack,
@@ -735,15 +781,14 @@ class TrackSelectionService {
           return TrackSelectionResult(subtitleToSelect, TrackSelectionPriority.navigation);
         }
       }
+      if (preferredSubtitleTrack.id.startsWith('source:')) return null;
     }
 
     // Priority 2: Trust the server's selected track. Plex computes this from
     // account/show/per-item prefs; Jellyfin exposes DefaultSubtitleStreamIndex.
     final info = plexMediaInfo;
     if (info != null) {
-      final serverSelectedTrack = availableTracks.isNotEmpty
-          ? info.subtitleTracks.where((track) => track.selected).firstOrNull
-          : null;
+      final serverSelectedTrack = info.subtitleTracks.where((track) => track.selected).firstOrNull;
 
       if (serverSelectedTrack != null) {
         final matchedMpvTrack = findMpvTrackForPlexSubtitle(
@@ -755,6 +800,7 @@ class TrackSelectionService {
         if (matchedMpvTrack != null) {
           return TrackSelectionResult(matchedMpvTrack, TrackSelectionPriority.serverSelected);
         }
+        if (metadata.backend == MediaBackend.plex) return null;
       } else if (metadata.backend == MediaBackend.jellyfin) {
         final defaultStreamIndex = info.defaultSubtitleStreamIndex;
         if (defaultStreamIndex == -1) {
@@ -779,9 +825,11 @@ class TrackSelectionService {
           }
         }
       } else if (metadata.backend == MediaBackend.plex && info.subtitleTracks.isNotEmpty) {
-        // Server has subtitle tracks but none selected — trust that decision
+        if (availableTracks.isEmpty) return null;
+        // Native tracks exist and none maps to a server-selected stream.
         return TrackSelectionResult(SubtitleTrack.off, TrackSelectionPriority.serverSelected);
       }
+      if (availableTracks.isEmpty && info.subtitleTracks.isNotEmpty) return null;
     }
 
     // Priority 3: Apply server profile subtitle mode when the backend exposes
@@ -856,8 +904,10 @@ class TrackSelectionService {
       }
     }
 
-    // Select and apply subtitle track
+    // Select and apply subtitle track. A null result means source metadata
+    // advertises subtitles that the native player has not exposed yet.
     final subtitleResult = selectSubtitleTrack(realSubtitleTracks, preferredSubtitleTrack, selectedAudioTrack);
+    if (subtitleResult != null) {
       final selectedSubtitleTrack = subtitleResult.track;
       final subtitleName = selectedSubtitleTrack.id == 'no'
           ? 'OFF'
@@ -873,6 +923,9 @@ class TrackSelectionService {
       if (subtitleResult.priority == TrackSelectionPriority.navigation && onSubtitleTrackChanged != null) {
         onSubtitleTrackChanged(selectedSubtitleTrack);
       }
+    } else {
+      appLogger.d('Subtitle selection pending: native tracks have not arrived');
+    }
 
     // Apply preferred secondary subtitle track if provided (mpv-only)
     if (preferredSecondarySubtitleTrack != null &&

test/mpv/player_open_test.dart

@@ -244,7 +244,7 @@ void main() {
       );
     });
 
-    test('ExoPlayer forwards external subtitle metadata at open', () async {
+    test('ExoPlayer forwards complete container metadata and rejects empty sidecar URIs', () async {
       final calls = <MethodCall>[];
 
       await withMockPlayerChannels(
@@ -252,18 +252,14 @@ void main() {
         eventChannelName: 'com.plezy/exo_player/events',
         methodHandler: (call) {
           calls.add(call);
-          switch (call.method) {
-            case 'initialize':
-              return Future.value(true);
-            default:
-              return Future.value(null);
-          }
+          return call.method == 'initialize' ? Future.value(true) : Future.value(null);
         },
         testBody: () async {
           final player = PlayerAndroid();
           try {
+            const containerUri = 'https://example.test/movie.mkv';
             await player.open(
-              Media('https://example.test/movie.mkv'),
+              Media('https://example.test/transcode.m3u8'),
               externalSubtitles: const [
                 SubtitleTrack(
                   id: 'external-sub',
@@ -275,20 +271,44 @@ void main() {
                   isExternal: true,
                   uri: 'https://example.test/sub.srt',
                 ),
+                SubtitleTrack(
+                  id: 'container:1',
+                  title: 'English Dialogue',
+                  language: 'eng',
+                  codec: 'ass',
+                  isDefault: true,
+                  isExternal: true,
+                  isContainer: true,
+                  uri: containerUri,
+                ),
+                SubtitleTrack(
+                  id: 'container:2',
+                  title: 'English Signs',
+                  language: 'eng',
+                  codec: 'ass',
+                  isForced: true,
+                  isExternal: true,
+                  isContainer: true,
+                  uri: containerUri,
+                ),
+                SubtitleTrack(id: 'invalid', uri: '', isExternal: true, isContainer: true),
               ],
             );
 
             final openCall = calls.singleWhere((call) => call.method == 'open');
             final args = Map<Object?, Object?>.from(openCall.arguments as Map);
-            final external = args['externalSubtitles'] as List;
-            final subtitle = Map<Object?, Object?>.from(external.single as Map);
+            final external = (args['externalSubtitles'] as List)
+                .map((entry) => Map<Object?, Object?>.from(entry as Map))
+                .toList();
 
-            expect(subtitle['uri'], 'https://example.test/sub.srt');
-            expect(subtitle['title'], 'English Forced');
-            expect(subtitle['language'], 'eng');
-            expect(subtitle['codec'], 'srt');
-            expect(subtitle['isDefault'], isTrue);
-            expect(subtitle['isForced'], isTrue);
+            expect(external, hasLength(3));
+            expect(external.first['uri'], 'https://example.test/sub.srt');
+            expect(external.first['title'], 'English Forced');
+            expect(external.first['isDefault'], isTrue);
+            expect(external.first['isForced'], isTrue);
+            expect(external.skip(1).map((entry) => entry['uri']).toSet(), {containerUri});
+            expect(external.skip(1).map((entry) => entry['title']), ['English Dialogue', 'English Signs']);
+            expect(external.skip(1).every((entry) => entry['isContainer'] == true), isTrue);
           } finally {
             await player.dispose();
           }
@@ -612,41 +632,119 @@ void main() {
       );
     });
 
-    test('MPV preserves external subtitle metadata for loadfile sidecars', () async {
+    test('MPV restores per-stream metadata while loading a shared container once', () async {
+      final calls = <MethodCall>[];
       await withMockPlayerChannels(
         methodChannelName: 'com.plezy/mpv_player',
         eventChannelName: 'com.plezy/mpv_player/events',
+        methodHandler: (call) {
+          calls.add(call);
+          return call.method == 'initialize' ? Future.value(true) : Future.value(null);
+        },
         testBody: () async {
           final player = PlayerNative();
           try {
-            const subtitleUri = 'https://example.test/subtitles/en-forced.srt';
+            const subtitleUri = 'https://example.test/movie.mkv?X-Plex-Token=secret';
             await player.open(
-              Media('https://example.test/movie.mkv'),
+              Media('https://example.test/transcode.m3u8'),
               externalSubtitles: const [
                 SubtitleTrack(
-                  id: 'server-subtitle',
+                  id: 'container:1',
                   uri: subtitleUri,
-                  title: 'English Forced',
+                  title: 'English Dialogue',
                   language: 'eng',
-                  codec: 'srt',
+                  codec: 'ass',
                   isDefault: true,
+                  isExternal: true,
+                  isContainer: true,
+                ),
+                SubtitleTrack(
+                  id: 'container:2',
+                  uri: subtitleUri,
+                  title: 'English Signs',
+                  language: 'eng',
+                  codec: 'ass',
                   isForced: true,
                   isExternal: true,
+                  isContainer: true,
                 ),
               ],
             );
-
-            player.handlePropertyChange('track-list', const [
-              {'type': 'sub', 'id': '1', 'codec': 'subrip', 'external': true, 'external-filename': subtitleUri},
+            expect(_loadfileArgs(calls), [
+              'loadfile',
+              'https://example.test/transcode.m3u8',
+              'replace',
+              '-1',
+              'sub-files=${_fixedLengthPathList([subtitleUri])}',
             ]);
 
-            final subtitle = player.state.tracks.subtitle.single;
-            expect(subtitle.title, 'English Forced');
-            expect(subtitle.language, 'eng');
-            expect(subtitle.codec, 'srt');
-            expect(subtitle.isDefault, isTrue);
-            expect(subtitle.isForced, isTrue);
-            expect(subtitle.uri, subtitleUri);
+            player.handlePropertyChange('track-list', const [
+              {'type': 'audio', 'id': 'sidecar-audio', 'external': true, 'external-filename': subtitleUri},
+              {
+                'type': 'sub',
+                'id': '1',
+                'title': 'movie.mkv?X-Plex-Token=secret',
+                'default': false,
+                'forced': false,
+                'external': true,
+                'external-filename': subtitleUri,
+              },
+              {
+                'type': 'sub',
+                'id': '2',
+                'title': 'movie.mkv?X-Plex-Token=secret',
+                'default': false,
+                'forced': false,
+                'external': true,
+                'external-filename': subtitleUri,
+              },
+            ]);
+
+            expect(player.state.tracks.audio, isEmpty);
+            final subtitles = player.state.tracks.subtitle;
+            expect(subtitles, hasLength(2));
+            expect(subtitles.map((track) => track.title), ['English Dialogue', 'English Signs']);
+            expect(subtitles.map((track) => track.language), ['eng', 'eng']);
+            expect(subtitles.map((track) => track.codec), ['ass', 'ass']);
+            expect(subtitles.map((track) => track.isDefault), [true, false]);
+            expect(subtitles.map((track) => track.isForced), [false, true]);
+            expect(subtitles.every((track) => track.uri == subtitleUri && track.isContainer), isTrue);
+          } finally {
+            await player.dispose();
+          }
+        },
+      );
+    });
+
+    test('MPV keeps native metadata fallbacks for non-container subtitles', () async {
+      await withMockPlayerChannels(
+        methodChannelName: 'com.plezy/mpv_player',
+        eventChannelName: 'com.plezy/mpv_player/events',
+        methodHandler: (call) => call.method == 'initialize' ? Future.value(true) : Future.value(null),
+        testBody: () async {
+          final player = PlayerNative();
+          try {
+            const sidecarUri = 'https://example.test/subtitle.srt';
+            await player.open(
+              Media('https://example.test/movie.mkv'),
+              externalSubtitles: const [SubtitleTrack(id: 'external', uri: sidecarUri, isExternal: true)],
+            );
+
+            player.handlePropertyChange('track-list', const [
+              {
+                'type': 'sub',
+                'id': 'external',
+                'title': 'English Dialogue - SRT',
+                'lang': 'eng',
+                'codec': 'subrip',
+                'external': true,
+                'external-filename': sidecarUri,
+              },
+              {'type': 'sub', 'id': 'embedded', 'title': 'French Dialogue - ASS', 'lang': 'fre', 'codec': 'ass'},
+            ]);
+
+            expect(player.state.tracks.subtitle.map((track) => track.title), ['English Dialogue', 'French Dialogue']);
+            expect(player.state.tracks.subtitle.map((track) => track.language), ['eng', 'fre']);
           } finally {
             await player.dispose();
           }

test/services/playback_subtitle_resolver_test.dart

@@ -11,6 +11,7 @@ import '../test_helpers/media_items.dart';
 MediaSubtitleTrack _sourceSubtitle(
   int id, {
   String language = 'eng',
+  String codec = 'srt',
   bool forced = false,
   bool selected = false,
   bool external = false,
@@ -20,6 +21,7 @@ MediaSubtitleTrack _sourceSubtitle(
     id: id,
     language: language,
     languageCode: language,
+    codec: codec,
     title: 'Subtitle $id',
     selected: selected,
     forced: forced,
@@ -28,16 +30,30 @@ MediaSubtitleTrack _sourceSubtitle(
   );
 }
 
-PlaybackSubtitleSidecar _sidecar(int id, {String language = 'eng', bool isDefault = false}) {
+PlaybackSubtitleSidecar _sidecar(
+  int id, {
+  String language = 'eng',
+  bool isDefault = false,
+  bool preload = false,
+  bool isContainer = false,
+  String? uri,
+}) {
+  final sidecarUri = uri ?? 'https://example.test/subtitles/$id.srt';
   return PlaybackSubtitleSidecar(
     sourceStreamId: id,
-    track: SubtitleTrack.uri(
-      'https://example.test/subtitles/$id.srt',
+    preload: preload,
+    track: isContainer
+        ? SubtitleTrack(
+            id: 'container:$id',
             title: 'Subtitle $id',
             language: language,
             codec: 'srt',
             isDefault: isDefault,
-    ),
+            isExternal: true,
+            isContainer: true,
+            uri: sidecarUri,
+          )
+        : SubtitleTrack.uri(sidecarUri, title: 'Subtitle $id', language: language, codec: 'srt', isDefault: isDefault),
   );
 }
 
@@ -46,17 +62,18 @@ MediaSourceInfo _mediaInfo(List<MediaSubtitleTrack> subtitles) {
 }
 
 void main() {
-  group('direct-play source routing', () {
+  group('source subtitle routing', () {
     test('matches an embedded source to its loaded native track', () {
       final source = _sourceSubtitle(2, language: 'eng');
       const native = SubtitleTrack(id: '7', language: 'eng', codec: 'srt');
 
       expect(
-        PlaybackSubtitleResolver.nativeTrackForDirectPlaySource(
+        PlaybackSubtitleResolver.nativeTrackForSource(
           sourceTrack: source,
           nativeTracks: const [native],
           allSourceTracks: [source],
           isResolvedSidecar: false,
+          isContainerSidecar: false,
         ),
         native,
       );
@@ -81,11 +98,12 @@ void main() {
       );
 
       expect(
-        PlaybackSubtitleResolver.nativeTrackForDirectPlaySource(
+        PlaybackSubtitleResolver.nativeTrackForSource(
           sourceTrack: source,
           nativeTracks: const [other],
           allSourceTracks: [source],
           isResolvedSidecar: true,
+          isContainerSidecar: false,
         ),
         isNull,
       );
@@ -117,15 +135,50 @@ void main() {
       const native = SubtitleTrack(id: '7', language: 'eng', codec: 'srt');
 
       expect(
-        PlaybackSubtitleResolver.nativeTrackForDirectPlaySource(
+        PlaybackSubtitleResolver.nativeTrackForSource(
           sourceTrack: source,
           nativeTracks: const [native],
           allSourceTracks: [source],
           isResolvedSidecar: false,
+          isContainerSidecar: false,
         ),
         native,
       );
     });
+    test('matches a requested source among tracks from one container sidecar', () {
+      final sources = [_sourceSubtitle(2, language: 'eng'), _sourceSubtitle(3, language: 'eng')];
+      const nativeTracks = [
+        SubtitleTrack(
+          id: '7',
+          title: 'Subtitle 2',
+          language: 'eng',
+          codec: 'srt',
+          isExternal: true,
+          isContainer: true,
+          uri: 'https://example.test/video.mkv',
+        ),
+        SubtitleTrack(
+          id: '8',
+          title: 'Subtitle 3',
+          language: 'eng',
+          codec: 'srt',
+          isExternal: true,
+          isContainer: true,
+          uri: 'https://example.test/video.mkv',
+        ),
+      ];
+
+      expect(
+        PlaybackSubtitleResolver.nativeTrackForSource(
+          sourceTrack: sources.last,
+          nativeTracks: nativeTracks,
+          allSourceTracks: sources,
+          isResolvedSidecar: true,
+          isContainerSidecar: true,
+        ),
+        nativeTracks.last,
+      );
+    });
   });
 
   final metadata = testMediaItem(id: 'movie-1', backend: MediaBackend.jellyfin, kind: MediaKind.movie);
@@ -160,6 +213,24 @@ void main() {
     expect(result.sidecarsAtOpen, isEmpty);
   });
 
+  test('retains each source metadata row for a shared preloaded container', () {
+    final result = PlaybackSubtitleResolver.resolve(
+      metadata: metadata,
+      mediaInfo: _mediaInfo([_sourceSubtitle(2, selected: true), _sourceSubtitle(3)]),
+      sidecars: [
+        _sidecar(2, preload: true, isContainer: true, uri: 'https://example.test/video.mkv'),
+        _sidecar(3, preload: true, isContainer: true, uri: 'https://example.test/video.mkv'),
+      ],
+      preferredSubtitleTrack: SubtitleTrack.off,
+    );
+
+    expect(result.isOff, isTrue);
+    expect(result.sidecarsAtOpen, hasLength(2));
+    expect(result.sidecarsAtOpen.every((track) => track.isContainer), isTrue);
+    expect(result.sidecarsAtOpen.map((track) => track.id), ['container:2', 'container:3']);
+    expect(result.sidecarsAtOpen.map((track) => track.uri).toSet(), {'https://example.test/video.mkv'});
+  });
+
   test('explicit source selection wins over the server default', () {
     final mediaInfo = _mediaInfo([
       _sourceSubtitle(2, selected: true, usesExternalDelivery: true),
@@ -179,6 +250,82 @@ void main() {
     expect(result.sidecarsAtOpen.single.uri, 'https://example.test/subtitles/3.srt');
   });
 
+  test('explicit source identity wins when subtitle metadata is identical', () {
+    final mediaInfo = _mediaInfo([
+      MediaSubtitleTrack(
+        id: 2,
+        language: 'eng',
+        languageCode: 'eng',
+        codec: 'ass',
+        title: 'English',
+        selected: true,
+        forced: false,
+      ),
+      MediaSubtitleTrack(
+        id: 3,
+        language: 'eng',
+        languageCode: 'eng',
+        codec: 'ass',
+        title: 'English',
+        selected: false,
+        forced: false,
+      ),
+    ]);
+    final result = PlaybackSubtitleResolver.resolve(
+      metadata: metadata,
+      mediaInfo: mediaInfo,
+      sidecars: [
+        _sidecar(2, isContainer: true, uri: 'https://example.test/video.mkv'),
+        _sidecar(3, isContainer: true, uri: 'https://example.test/video.mkv'),
+      ],
+      preferredSubtitleTrack: PlaybackSubtitleResolver.preferredTrackForSource(mediaInfo, 3),
+    );
+
+    expect(result.primarySourceStreamId, 3);
+  });
+
+  test('source identity is ignored across media-source changes', () {
+    final result = PlaybackSubtitleResolver.resolve(
+      metadata: metadata,
+      mediaInfo: _mediaInfo([
+        _sourceSubtitle(3, language: 'eng', selected: true, usesExternalDelivery: true),
+        _sourceSubtitle(7, language: 'fra', usesExternalDelivery: true),
+      ]),
+      sidecars: [
+        _sidecar(3),
+        _sidecar(7, language: 'fra'),
+      ],
+      preferredSubtitleTrack: const SubtitleTrack(
+        id: 'source:3',
+        title: 'French from the previous source',
+        language: 'fra',
+        codec: 'srt',
+        isExternal: true,
+        uri: 'https://example.test/previous/3.srt',
+      ),
+      preserveSourceIdentity: false,
+    );
+
+    expect(result.primarySourceStreamId, 7);
+  });
+
+  test('unmatched source identity cannot bind a reused id after a source change', () {
+    final result = PlaybackSubtitleResolver.resolve(
+      metadata: metadata,
+      mediaInfo: _mediaInfo([_sourceSubtitle(3, language: 'eng'), _sourceSubtitle(7, language: 'spa', selected: true)]),
+      sidecars: const [],
+      preferredSubtitleTrack: const SubtitleTrack(
+        id: 'source:3',
+        title: 'French from the previous source',
+        language: 'fra',
+        codec: 'srt',
+      ),
+      preserveSourceIdentity: false,
+    );
+
+    expect(result.primarySourceStreamId, 7);
+  });
+
   test('item-change semantic preference selects the matching new sidecar', () {
     final result = PlaybackSubtitleResolver.resolve(
       metadata: metadata,
@@ -240,6 +387,17 @@ void main() {
     expect(result.sidecarsAtOpen, isEmpty);
   });
 
+  test('selected metadata-free embedded subtitle resolves by source identity', () {
+    final result = PlaybackSubtitleResolver.resolve(
+      metadata: metadata,
+      mediaInfo: _mediaInfo([MediaSubtitleTrack(id: 2, codec: 'ass', selected: true, forced: false)]),
+      sidecars: const [],
+    );
+
+    expect(result.isOff, isFalse);
+    expect(result.primarySourceStreamId, 2);
+  });
+
   test('preferred secondary subtitle attaches a second distinct sidecar', () {
     final mediaInfo = _mediaInfo([
       _sourceSubtitle(2, selected: true, usesExternalDelivery: true),

test/services/plex_playback_data_request_test.dart

@@ -10,7 +10,6 @@ import 'package:plezy/media/media_backend.dart';
 
 import 'package:plezy/media/media_kind.dart';
 import 'package:plezy/media/media_source_info.dart';
-import 'package:plezy/mpv/mpv.dart';
 import 'package:plezy/models/transcode_quality_preset.dart';
 import 'package:plezy/services/playback_initialization_types.dart';
 import 'package:plezy/services/plex_api_cache.dart';
@@ -44,8 +43,11 @@ void main() {
     );
   }
 
-  List<SubtitleTrack> buildTranscodeSubtitles(PlexClient client, List<MediaSubtitleTrack> subtitleTracks) {
-    return client.buildTranscodeSidecarSubtitlesForTesting(mediaInfoWithSubtitles(subtitleTracks));
+  List<PlaybackSubtitleSidecar> buildTranscodeSubtitles(PlexClient client, List<MediaSubtitleTrack> subtitleTracks) {
+    return client.buildTranscodeSidecarSubtitlesForTesting(
+      mediaInfoWithSubtitles(subtitleTracks),
+      'https://plex.example.com/video.mkv?X-Plex-Token=token',
+    );
   }
 
   test('selectStreams sends audio stream selection with allParts', () async {
@@ -129,6 +131,97 @@ void main() {
     expect(data.mediaInfo?.subtitleTracks.single.selected, isTrue);
   });
 
+  test('transcode initialization wires a subtitle-free HLS request to the complete sidecar catalog', () async {
+    final requests = <http.Request>[];
+    final client = makeClient((request) async {
+      requests.add(request);
+      if (request.url.path == '/library/metadata/42') {
+        return http.Response(
+          jsonEncode({
+            'MediaContainer': {
+              'Metadata': [
+                {
+                  'ratingKey': '42',
+                  'type': 'movie',
+                  'title': 'Movie',
+                  'Media': [
+                    {
+                      'id': 7,
+                      'container': 'mkv',
+                      'Part': [
+                        {
+                          'id': 99,
+                          'key': '/library/parts/99/file.mkv',
+                          'Stream': [
+                            {'streamType': 1, 'id': 300, 'codec': 'h264'},
+                            {'streamType': 2, 'id': 301, 'index': 0, 'languageCode': 'jpn', 'selected': true},
+                            {
+                              'streamType': 3,
+                              'id': 401,
+                              'index': 1,
+                              'codec': 'ass',
+                              'languageCode': 'eng',
+                              'selected': true,
+                            },
+                            {
+                              'streamType': 3,
+                              'id': 402,
+                              'index': 2,
+                              'codec': 'srt',
+                              'languageCode': 'swe',
+                              'key': '/library/streams/402',
+                              'external': true,
+                            },
+                          ],
+                        },
+                      ],
+                    },
+                  ],
+                },
+              ],
+            },
+          }),
+          200,
+          headers: {'content-type': 'application/json'},
+        );
+      }
+      if (request.url.path == '/video/:/transcode/universal/decision') {
+        return http.Response(
+          jsonEncode({
+            'MediaContainer': {'generalDecisionCode': 1001, 'transcodeDecisionCode': 1001},
+          }),
+          200,
+          headers: {'content-type': 'application/json'},
+        );
+      }
+      return http.Response('unexpected request', 500);
+    });
+    addTearDown(client.close);
+
+    final result = await client.getPlaybackInitialization(
+      PlaybackInitializationOptions(
+        metadata: testMediaItem(id: '42', backend: MediaBackend.plex, kind: MediaKind.movie, serverId: 'server-id'),
+        selectedMediaIndex: 0,
+        qualityPreset: TranscodeQualityPreset.p720_3mbps,
+        sessionIdentifier: 'session-id',
+        transcodeSessionId: 'transcode-id',
+      ),
+    );
+
+    final decisionRequest = requests.singleWhere(
+      (request) => request.url.path == '/video/:/transcode/universal/decision',
+    );
+    expect(decisionRequest.url.queryParameters['subtitles'], 'none');
+    expect(decisionRequest.url.queryParameters.containsKey('subtitleStreamID'), isFalse);
+    expect(decisionRequest.url.queryParameters.containsKey('advancedSubtitles'), isFalse);
+    expect(result.isTranscoding, isTrue);
+    expect(result.videoUrl, contains('/video/:/transcode/universal/start.m3u8?'));
+    expect(result.subtitleSidecars.map((sidecar) => sidecar.sourceStreamId), [401, 402]);
+    expect(result.subtitleSidecars.every((sidecar) => sidecar.preload), isTrue);
+    expect(result.subtitleSidecars.first.track.isContainer, isTrue);
+    expect(result.subtitleSidecars.last.track.uri, contains('/library/streams/402.srt'));
+  });
+
   test('playback uses metadata availability flags without probing part URLs', () async {
     final requests = <http.Request>[];
     final client = makeClient((request) async {
@@ -331,16 +424,17 @@ void main() {
     expect(result.selectedMediaIndex, 1);
   });
 
-  test('transcode subtitle sidecars only use real Plex stream keys', () {
+  test('transcode subtitle catalog includes embedded and keyed Plex streams', () {
     final client = makeClient((_) async => http.Response('not used', 500));
     addTearDown(client.close);
 
     final subtitles = buildTranscodeSubtitles(client, [
-      MediaSubtitleTrack(id: 401, codec: 'srt', languageCode: 'eng', selected: false, forced: false),
+      MediaSubtitleTrack(id: 401, codec: 'ass', languageCode: 'eng', title: 'Embedded', selected: true, forced: false),
       MediaSubtitleTrack(
         id: 402,
         codec: 'srt',
-        languageCode: 'eng',
+        languageCode: 'swe',
+        title: 'External',
         selected: false,
         forced: false,
         key: '/library/streams/402',
@@ -348,63 +442,50 @@ void main() {
       ),
     ]);
 
-    expect(subtitles, hasLength(1));
-    expect(subtitles.single.uri, 'https://plex.example.com/library/streams/402.srt?encoding=utf-8&X-Plex-Token=token');
-  });
-
-  test('transcode negotiation honors an explicit source subtitle preference', () {
-    final client = makeClient((_) async => http.Response('not used', 500));
-    addTearDown(client.close);
-    final info = mediaInfoWithSubtitles([
-      MediaSubtitleTrack(id: 401, languageCode: 'eng', selected: true, forced: false),
-      MediaSubtitleTrack(id: 402, languageCode: 'swe', selected: false, forced: false),
-    ]);
-
-    final selected = client.resolveTranscodeSubtitleTrackForTesting(
-      info,
-      const SubtitleTrack(id: 'source:402', language: 'swe'),
+    expect(subtitles, hasLength(2));
+    expect(subtitles.map((sidecar) => sidecar.sourceStreamId), [401, 402]);
+    expect(subtitles.every((sidecar) => sidecar.preload), isTrue);
+    expect(subtitles.first.track.isContainer, isTrue);
+    expect(subtitles.first.track.uri, 'https://plex.example.com/video.mkv?X-Plex-Token=token');
+    expect(subtitles.last.track.isContainer, isFalse);
+    expect(
+      subtitles.last.track.uri,
+      'https://plex.example.com/library/streams/402.srt?encoding=utf-8&X-Plex-Token=token',
     );
-
-    expect(selected?.id, 402);
-    expect(client.resolveTranscodeSubtitleTrackForTesting(info, SubtitleTrack.off), isNull);
   });
 
-  test('transcode negotiation falls back to the new source default for a stale source id', () {
-    final client = makeClient((_) async => http.Response('not used', 500));
-    addTearDown(client.close);
-    final info = mediaInfoWithSubtitles([
-      MediaSubtitleTrack(id: 501, languageCode: 'eng', selected: true, forced: false),
-      MediaSubtitleTrack(id: 502, languageCode: 'swe', selected: false, forced: false),
-    ]);
-
-    final selected = client.resolveTranscodeSubtitleTrackForTesting(
-      info,
-      const SubtitleTrack(id: 'source:402', language: 'und'),
+  test('tokenless transcode keeps embedded and keyed subtitle sources', () {
+    final client = testPlexClient(
+      serverId: ServerId('server-id'),
+      token: null,
+      handler: (_) async => http.Response('not used', 500),
     );
-
-    expect(selected?.id, 501);
-  });
-
-  test('selected internal text subtitles are not attached as external sidecars', () {
-    final client = makeClient((_) async => http.Response('not used', 500));
     addTearDown(client.close);
 
-    final subtitles = buildTranscodeSubtitles(client, [
+    final subtitles = client.buildTranscodeSidecarSubtitlesForTesting(
+      mediaInfoWithSubtitles([
+        MediaSubtitleTrack(id: 401, codec: 'ass', languageCode: 'eng', selected: true, forced: false),
         MediaSubtitleTrack(
-        id: 401,
-        codec: 'ass',
-        language: 'English',
-        languageCode: 'eng',
-        title: 'Signs/Songs',
-        selected: true,
+          id: 402,
+          codec: 'srt',
+          languageCode: 'swe',
+          selected: false,
           forced: false,
+          key: '/library/streams/402',
+          external: true,
         ),
-    ]);
+      ]),
+      'https://plex.example.com/video.mkv',
+    );
 
-    expect(subtitles, isEmpty);
+    expect(subtitles, hasLength(2));
+    expect(subtitles.first.track.isContainer, isTrue);
+    expect(subtitles.first.track.uri, 'https://plex.example.com/video.mkv');
+    expect(subtitles.last.track.isContainer, isFalse);
+    expect(subtitles.last.track.uri, 'https://plex.example.com/library/streams/402.srt?encoding=utf-8');
   });
 
-  test('selected internal text subtitles are segmented into the HLS transcode', () {
+  test('video transcode stays subtitle-free while preserving the HLS profile', () {
     final client = makeClient((_) async => http.Response('not used', 500));
     addTearDown(client.close);
 
@@ -414,19 +495,12 @@ void main() {
       preset: TranscodeQualityPreset.p720_3mbps,
       sessionIdentifier: 'session-id',
       transcodeSessionId: 'transcode-id',
-      selectedSubtitleTrack: MediaSubtitleTrack(
-        id: 401,
-        codec: 'ass',
-        languageCode: 'eng',
-        selected: true,
-        forced: false,
-      ),
     );
 
     expect(params['protocol'], 'hls');
-    expect(params['subtitles'], 'segmented');
-    expect(params['subtitleStreamID'], '401');
-    expect(params['advancedSubtitles'], 'text');
+    expect(params['subtitles'], 'none');
+    expect(params.containsKey('subtitleStreamID'), isFalse);
+    expect(params.containsKey('advancedSubtitles'), isFalse);
     expect(params.containsKey('X-Plex-Chunked'), isFalse);
     expect(params['X-Plex-Incomplete-Segments'], '1');
     expect(params['X-Plex-Client-Profile-Name'], 'Generic');
@@ -444,8 +518,7 @@ void main() {
       profile,
       contains(
         'add-transcode-target(type=videoProfile&context=streaming'
-        '&protocol=hls&container=mpegts&videoCodec=h264%2Chevc%2Cmpeg2video'
-        '&audioCodec=aac%2Cac3%2Ceac3%2Cmp3)',
+        '&protocol=hls&container=mpegts',
       ),
     );
     expect(
@@ -495,43 +568,20 @@ void main() {
     expect(params['partIndex'], '2');
   });
 
-  test('selected image subtitles are burned into HLS without advancedSubtitles', () {
+  test('image-based embedded subtitles use the shared container sidecar', () {
     final client = makeClient((_) async => http.Response('not used', 500));
     addTearDown(client.close);
 
-    final params = client.buildTranscodeParamsForTesting(
-      ratingKey: '42',
-      mediaIndex: 0,
-      preset: TranscodeQualityPreset.p720_3mbps,
-      sessionIdentifier: 'session-id',
-      transcodeSessionId: 'transcode-id',
-      selectedSubtitleTrack: MediaSubtitleTrack(
-        id: 401,
-        codec: 'pgs',
-        languageCode: 'eng',
-        selected: true,
-        forced: false,
-      ),
-    );
-
-    expect(params['subtitles'], 'burn');
-    expect(params['subtitleStreamID'], '401');
-    expect(params['protocol'], 'hls');
-    expect(params.containsKey('advancedSubtitles'), isFalse);
-  });
-
-  test('image-based embedded subtitles are rendered by HLS, not attached as sidecars', () {
-    final client = makeClient((_) async => http.Response('not used', 500));
-    addTearDown(client.close);
-
-    // Embedded bitmap streams have no Plex `key`; the HLS request burns the
-    // selected track into the video rendition.
     final subtitles = buildTranscodeSubtitles(client, [
       MediaSubtitleTrack(id: 401, codec: 'pgs', languageCode: 'eng', selected: true, forced: false),
-      MediaSubtitleTrack(id: 402, codec: 'dvd_subtitle', languageCode: 'eng', selected: true, forced: false),
+      MediaSubtitleTrack(id: 402, codec: 'dvd_subtitle', languageCode: 'eng', selected: false, forced: false),
     ]);
 
-    expect(subtitles, isEmpty);
+    expect(subtitles, hasLength(2));
+    expect(subtitles.every((sidecar) => sidecar.track.isContainer), isTrue);
+    expect(subtitles.map((sidecar) => sidecar.track.uri).toSet(), {
+      'https://plex.example.com/video.mkv?X-Plex-Token=token',
+    });
   });
 
   group('playback metadata failure contract', () {

test/services/track_manager_test.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 
+import 'package:fake_async/fake_async.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:plezy/media/media_backend.dart';
 import 'package:plezy/media/media_item.dart';
@@ -7,6 +8,8 @@ import 'package:plezy/media/media_kind.dart';
 import 'package:plezy/media/media_source_info.dart';
 import 'package:plezy/mpv/mpv.dart';
 import 'package:plezy/mpv/player/player_stream_controllers.dart';
+import 'package:plezy/screens/video_player_screen.dart';
+import 'package:plezy/services/playback_initialization_types.dart';
 import 'package:plezy/services/settings_service.dart';
 import 'package:plezy/services/track_manager.dart';
 
@@ -369,6 +372,361 @@ void main() {
       expect(player.selectedSubtitle, hasLength(1));
       expect(player.selectedSubtitle.single.id, 'no');
     });
+
+    test('waits through a partial catalog until the selected Plex subtitle arrives', () async {
+      await SettingsService.getInstance();
+      final player = _FakePlayer(
+        tracks: const Tracks(
+          audio: [AudioTrack(id: '1', language: 'eng')],
+        ),
+      );
+      final mgr = _make(player: player, mediaInfo: _mediaInfoWithSubtitles(selected: true));
+      addTearDown(mgr.dispose);
+
+      mgr.applyTrackSelectionWhenReady();
+      player.emitTracks(
+        const Tracks(
+          audio: [AudioTrack(id: '1', language: 'eng')],
+          subtitle: [SubtitleTrack(id: '11', language: 'fre')],
+        ),
+      );
+      await _drainAsync();
+      expect(player.selectedSubtitle, isEmpty);
+
+      player.emitTracks(
+        const Tracks(
+          audio: [AudioTrack(id: '1', language: 'eng')],
+          subtitle: [
+            SubtitleTrack(id: '11', language: 'fre'),
+            SubtitleTrack(id: '10', language: 'eng'),
+          ],
+        ),
+      );
+      await _drainAsync();
+
+      expect(player.selectedSubtitle.map((track) => track.id), ['10']);
+    });
+
+    test('waits for a preferred subtitle even when the server-selected track arrives first', () async {
+      await SettingsService.getInstance();
+      final player = _FakePlayer(
+        tracks: const Tracks(
+          audio: [AudioTrack(id: '1', language: 'eng')],
+        ),
+      );
+      final mgr = _make(
+        player: player,
+        mediaInfo: _mediaInfoWithSubtitles(selected: true),
+        preferredSubtitleTrack: const SubtitleTrack(id: 'previous', language: 'fre'),
+      );
+      addTearDown(mgr.dispose);
+
+      mgr.applyTrackSelectionWhenReady();
+      player.emitTracks(
+        const Tracks(
+          audio: [AudioTrack(id: '1', language: 'eng')],
+          subtitle: [SubtitleTrack(id: '10', language: 'eng')],
+        ),
+      );
+      await _drainAsync();
+      expect(player.selectedSubtitle, isEmpty);
+
+      player.emitTracks(
+        const Tracks(
+          audio: [AudioTrack(id: '1', language: 'eng')],
+          subtitle: [
+            SubtitleTrack(id: '10', language: 'eng'),
+            SubtitleTrack(id: '11', language: 'fre'),
+          ],
+        ),
+      );
+      await _drainAsync();
+
+      expect(player.selectedSubtitle.map((track) => track.id), ['11']);
+    });
+
+    test('source identity waits for the intended identical container track', () async {
+      await SettingsService.getInstance();
+      final mediaInfo = MediaSourceInfo(
+        videoUrl: 'https://example.com/transcode.m3u8',
+        partId: 99,
+        audioTracks: [MediaAudioTrack(id: 1, languageCode: 'eng', selected: true)],
+        subtitleTracks: [
+          MediaSubtitleTrack(
+            id: 30,
+            index: 0,
+            languageCode: 'eng',
+            title: 'English',
+            codec: 'ass',
+            selected: false,
+            forced: false,
+          ),
+          MediaSubtitleTrack(
+            id: 31,
+            index: 1,
+            languageCode: 'eng',
+            title: 'English',
+            codec: 'ass',
+            selected: true,
+            forced: false,
+          ),
+        ],
+        chapters: const [],
+      );
+      const firstNativeTrack = SubtitleTrack(
+        id: 'native-0',
+        language: 'eng',
+        title: 'English',
+        codec: 'ass',
+        isExternal: true,
+        isContainer: true,
+        uri: 'https://example.com/video.mkv',
+      );
+      const secondNativeTrack = SubtitleTrack(
+        id: 'native-1',
+        language: 'eng',
+        title: 'English',
+        codec: 'ass',
+        isExternal: true,
+        isContainer: true,
+        uri: 'https://example.com/video.mkv',
+      );
+      final player = _FakePlayer(
+        tracks: const Tracks(
+          audio: [AudioTrack(id: 'audio', language: 'eng')],
+          subtitle: [firstNativeTrack],
+        ),
+      );
+      final mgr = _make(
+        player: player,
+        mediaInfo: mediaInfo,
+        preferredSubtitleTrack: const SubtitleTrack(
+          id: 'source:31',
+          language: 'eng',
+          title: 'English',
+          codec: 'ass',
+          isExternal: true,
+          isContainer: true,
+          uri: 'https://example.com/video.mkv',
+        ),
+      );
+      addTearDown(mgr.dispose);
+
+      mgr.applyTrackSelectionWhenReady();
+      await _drainAsync();
+      expect(player.selectedSubtitle, isEmpty);
+
+      player.emitTracks(
+        const Tracks(
+          audio: [AudioTrack(id: 'audio', language: 'eng')],
+          subtitle: [firstNativeTrack, secondNativeTrack],
+        ),
+      );
+      await _drainAsync();
+
+      expect(player.selectedSubtitle.map((track) => track.id), ['native-1']);
+    });
+
+    test('deferred transcode source choice applies after native discovery without requesting a reload', () async {
+      await SettingsService.getInstance();
+      final sourceTrack = MediaSubtitleTrack(
+        id: 31,
+        index: 0,
+        languageCode: 'eng',
+        title: 'English',
+        codec: 'ass',
+        selected: false,
+        forced: false,
+      );
+      final mediaInfo = MediaSourceInfo(
+        videoUrl: 'https://example.com/transcode.m3u8',
+        partId: 99,
+        audioTracks: [MediaAudioTrack(id: 1, languageCode: 'eng', selected: true)],
+        subtitleTracks: [sourceTrack],
+        chapters: const [],
+      );
+      final player = _FakePlayer(
+        tracks: const Tracks(
+          audio: [AudioTrack(id: 'audio', language: 'eng')],
+        ),
+      );
+      final mgr = _make(player: player, mediaInfo: mediaInfo);
+      addTearDown(mgr.dispose);
+      SubtitleTrack? persistedTrack;
+      int? persistedSourceStreamId;
+
+      final handledLocally = await deferTranscodeSubtitleSelection(
+        trackManager: mgr,
+        sourceTrack: sourceTrack,
+        sourceSidecar: const PlaybackSubtitleSidecar(
+          sourceStreamId: 31,
+          preload: true,
+          track: SubtitleTrack(
+            id: 'container:31',
+            language: 'eng',
+            title: 'English',
+            codec: 'ass',
+            isExternal: true,
+            isContainer: true,
+            uri: 'https://example.com/video.mkv',
+          ),
+        ),
+        sourceStreamId: 31,
+        onSubtitleTrackChanged: (track, {sourceStreamId}) async {
+          persistedTrack = track;
+          persistedSourceStreamId = sourceStreamId;
+        },
+        shouldContinue: () => true,
+      );
+
+      expect(handledLocally, isTrue);
+      expect(mgr.preferredSubtitleTrack?.id, 'source:31');
+      expect(persistedTrack?.id, 'source:31');
+      expect(persistedSourceStreamId, 31);
+      expect(player.selectedSubtitle, isEmpty);
+
+      player.emitTracks(
+        const Tracks(
+          audio: [AudioTrack(id: 'audio', language: 'eng')],
+          subtitle: [
+            SubtitleTrack(
+              id: 'native-0',
+              language: 'eng',
+              title: 'English',
+              codec: 'ass',
+              isExternal: true,
+              isContainer: true,
+              uri: 'https://example.com/video.mkv',
+            ),
+          ],
+        ),
+      );
+      await _drainAsync();
+
+      expect(player.selectedSubtitle.map((track) => track.id), ['native-0']);
+    });
+
+    test('five-second fallback keeps listening and applies a late advertised subtitle', () async {
+      await SettingsService.getInstance();
+
+      fakeAsync((async) {
+        final player = _FakePlayer(
+          tracks: const Tracks(
+            audio: [AudioTrack(id: '1', language: 'eng')],
+          ),
+        );
+        final mgr = _make(player: player, mediaInfo: _mediaInfoWithSubtitles(selected: true));
+
+        mgr.applyTrackSelectionWhenReady();
+        async.elapse(const Duration(seconds: 5));
+        async.flushMicrotasks();
+
+        expect(player.selectedAudio, hasLength(1));
+        expect(player.selectedSubtitle, isEmpty);
+
+        player.emitTracks(
+          const Tracks(
+            audio: [AudioTrack(id: '1', language: 'eng')],
+            subtitle: [SubtitleTrack(id: '10', language: 'eng')],
+          ),
+        );
+        async.flushMicrotasks();
+
+        expect(player.selectedSubtitle.map((track) => track.id), ['10']);
+        expect(async.nonPeriodicTimerCount, 0);
+        mgr.dispose();
+      });
+    });
+
+    test('five-second fallback keeps listening through a partial subtitle catalog', () async {
+      await SettingsService.getInstance();
+
+      fakeAsync((async) {
+        final mediaInfo = MediaSourceInfo(
+          videoUrl: 'https://example.com/transcode.m3u8',
+          audioTracks: [MediaAudioTrack(id: 1, languageCode: 'eng', selected: true)],
+          subtitleTracks: [
+            MediaSubtitleTrack(id: 10, languageCode: 'eng', selected: false, forced: false),
+            MediaSubtitleTrack(id: 11, languageCode: 'fre', selected: true, forced: false),
+          ],
+          chapters: const [],
+        );
+        final player = _FakePlayer(
+          tracks: const Tracks(
+            audio: [AudioTrack(id: '1', language: 'eng')],
+            subtitle: [SubtitleTrack(id: '10', language: 'eng')],
+          ),
+        );
+        final mgr = _make(
+          player: player,
+          mediaInfo: mediaInfo,
+          preferredSubtitleTrack: const SubtitleTrack(id: 'source:11', language: 'fre'),
+        );
+
+        mgr.applyTrackSelectionWhenReady();
+        async.elapse(const Duration(seconds: 5));
+        async.flushMicrotasks();
+
+        expect(player.selectedAudio, hasLength(1));
+        expect(player.selectedSubtitle, isEmpty);
+
+        player.emitTracks(
+          const Tracks(
+            audio: [AudioTrack(id: '1', language: 'eng')],
+            subtitle: [
+              SubtitleTrack(id: '10', language: 'eng'),
+              SubtitleTrack(id: '11', language: 'fre'),
+            ],
+          ),
+        );
+        async.flushMicrotasks();
+
+        expect(player.selectedSubtitle.map((track) => track.id), ['11']);
+        expect(async.nonPeriodicTimerCount, 0);
+        mgr.dispose();
+      });
+    });
+
+    test('late subtitle arrival queues behind an in-flight fallback selection', () async {
+      await SettingsService.getInstance();
+
+      fakeAsync((async) {
+        final audioSelection = Completer<void>();
+        final player = _FakePlayer(
+          tracks: const Tracks(
+            audio: [AudioTrack(id: '1', language: 'eng')],
+          ),
+        );
+        var blockFirstAudioSelection = true;
+        player.onSelectAudioTrack = (_) {
+          if (!blockFirstAudioSelection) return Future<void>.value();
+          blockFirstAudioSelection = false;
+          return audioSelection.future;
+        };
+        final mgr = _make(player: player, mediaInfo: _mediaInfoWithSubtitles(selected: true));
+
+        mgr.applyTrackSelectionWhenReady();
+        async.elapse(const Duration(seconds: 5));
+        async.flushMicrotasks();
+        expect(player.selectedAudio, hasLength(1));
+
+        player.emitTracks(
+          const Tracks(
+            audio: [AudioTrack(id: '1', language: 'eng')],
+            subtitle: [SubtitleTrack(id: '10', language: 'eng')],
+          ),
+        );
+        async.flushMicrotasks();
+        expect(player.selectedSubtitle, isEmpty);
+
+        audioSelection.complete();
+        async.flushMicrotasks();
+
+        expect(player.selectedSubtitle.map((track) => track.id), ['10']);
+        expect(async.nonPeriodicTimerCount, 0);
+        mgr.dispose();
+      });
+    });
   });
 
   group('applyTrackSelection ownership', () {

test/services/track_selection_service_test.dart

@@ -99,7 +99,18 @@ SubtitleTrack _sub(
   String? codec,
   bool isDefault = false,
   bool isForced = false,
-}) => SubtitleTrack(id: id, language: lang, title: title, codec: codec, isDefault: isDefault, isForced: isForced);
+  bool isExternal = false,
+  bool isContainer = false,
+}) => SubtitleTrack(
+  id: id,
+  language: lang,
+  title: title,
+  codec: codec,
+  isDefault: isDefault,
+  isForced: isForced,
+  isExternal: isExternal,
+  isContainer: isContainer,
+);
 
 MediaAudioTrack _plexAudio(
   int id, {
@@ -132,6 +143,8 @@ MediaSubtitleTrack _plexSub(
   bool selected = false,
   bool forced = false,
   String? codec,
+  bool external = false,
+  String? key,
 }) {
   return MediaSubtitleTrack(
     id: id,
@@ -142,6 +155,8 @@ MediaSubtitleTrack _plexSub(
     selected: selected,
     forced: forced,
     codec: codec,
+    external: external,
+    key: key,
   );
 }
 
@@ -438,14 +453,14 @@ void main() {
   group('selectSubtitleTrack', () {
     test('Priority 1: preferred id="no" forces subtitles off', () {
       final tracks = [_sub('1', lang: 'eng', isDefault: true)];
-      final result = _svc().selectSubtitleTrack(tracks, const SubtitleTrack(id: 'no'), null);
+      final result = _svc().selectSubtitleTrack(tracks, const SubtitleTrack(id: 'no'), null)!;
       expect(result.priority, TrackSelectionPriority.navigation);
       expect(result.track.id, 'no');
     });
 
     test('Priority 1: preferred subtitle from navigation matches by language', () {
       final tracks = [_sub('1', lang: 'eng'), _sub('2', lang: 'fre')];
-      final result = _svc().selectSubtitleTrack(tracks, _sub('99', lang: 'fre'), null);
+      final result = _svc().selectSubtitleTrack(tracks, _sub('99', lang: 'fre'), null)!;
       expect(result.priority, TrackSelectionPriority.navigation);
       expect(result.track.id, '2');
     });
@@ -458,11 +473,90 @@ void main() {
           _plexSub(11, language: 'fre', languageCode: 'fre', selected: true),
         ],
       );
-      final result = _svc(info: info).selectSubtitleTrack(tracks, null, null);
+      final result = _svc(info: info).selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.serverSelected);
       expect(result.track.language, 'fre');
     });
 
+    test('partial native catalog stays undetermined until the selected Plex track arrives', () {
+      final info = _info(
+        subs: [
+          _plexSub(10, language: 'eng', selected: true),
+          _plexSub(11, language: 'fre'),
+        ],
+      );
+
+      final result = _svc(info: info).selectSubtitleTrack([_sub('2', lang: 'fre')], null, null);
+
+      expect(result, isNull);
+    });
+
+    test('preferred source waits for its ordinal in a partial identical container catalog', () {
+      final info = _info(
+        subs: [
+          _plexSub(30, index: 0, language: 'eng', title: 'English', codec: 'ass'),
+          _plexSub(31, index: 1, language: 'eng', title: 'English', codec: 'ass', selected: true),
+        ],
+      );
+      const preferred = SubtitleTrack(
+        id: 'source:31',
+        language: 'eng',
+        title: 'English',
+        codec: 'ass',
+        isExternal: true,
+        isContainer: true,
+        uri: 'https://example.test/video.mkv',
+      );
+      const first = SubtitleTrack(
+        id: 'native-0',
+        language: 'eng',
+        title: 'English',
+        codec: 'ass',
+        isExternal: true,
+        isContainer: true,
+        uri: 'https://example.test/video.mkv',
+      );
+      const second = SubtitleTrack(
+        id: 'native-1',
+        language: 'eng',
+        title: 'English',
+        codec: 'ass',
+        isExternal: true,
+        isContainer: true,
+        uri: 'https://example.test/video.mkv',
+      );
+      final service = _svc(info: info);
+
+      expect(service.selectSubtitleTrack(const [first], preferred, null), isNull);
+      expect(service.selectSubtitleTrack(const [first, second], preferred, null)?.track.id, 'native-1');
+    });
+
+    test('preferred keyed source does not fuzzy-match an early same-language container track', () {
+      final info = _info(
+        subs: [
+          _plexSub(10, language: 'eng', codec: 'srt', external: true, key: '/library/streams/10'),
+          _plexSub(11, language: 'eng', codec: 'srt'),
+        ],
+      );
+      const preferred = SubtitleTrack(
+        id: 'source:10',
+        language: 'eng',
+        codec: 'srt',
+        isExternal: true,
+        uri: 'https://example.test/library/streams/10.srt',
+      );
+      const earlyContainer = SubtitleTrack(
+        id: 'native-0',
+        language: 'eng',
+        codec: 'srt',
+        isExternal: true,
+        isContainer: true,
+        uri: 'https://example.test/video.mkv',
+      );
+
+      expect(_svc(info: info).selectSubtitleTrack(const [earlyContainer], preferred, null), isNull);
+    });
+
     test('Jellyfin selected subtitle stream wins over DefaultSubtitleStreamIndex', () {
       final tracks = [_sub('1', lang: 'eng'), _sub('2', lang: 'fre')];
       final info = _info(
@@ -475,7 +569,7 @@ void main() {
       final result = _svc(
         metadata: _meta(backend: MediaBackend.jellyfin),
         info: info,
-      ).selectSubtitleTrack(tracks, null, null);
+      ).selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.serverSelected);
       expect(result.track.language, 'fre');
     });
@@ -489,7 +583,7 @@ void main() {
           _plexSub(11, language: 'fre'),
         ],
       );
-      final result = _svc(info: info).selectSubtitleTrack(tracks, null, null);
+      final result = _svc(info: info).selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.serverSelected);
       expect(result.track.id, 'no');
     });
@@ -505,7 +599,7 @@ void main() {
       final result = _svc(
         metadata: _meta(backend: MediaBackend.jellyfin),
         info: info,
-      ).selectSubtitleTrack(tracks, null, null);
+      ).selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.defaultTrack);
       expect(result.track.id, '2');
     });
@@ -522,7 +616,7 @@ void main() {
       final result = _svc(
         metadata: _meta(backend: MediaBackend.jellyfin),
         info: info,
-      ).selectSubtitleTrack(tracks, null, null);
+      ).selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.serverSelected);
       expect(result.track.language, 'fre');
     });
@@ -539,7 +633,7 @@ void main() {
       final result = _svc(
         metadata: _meta(backend: MediaBackend.jellyfin),
         info: info,
-      ).selectSubtitleTrack(tracks, null, null);
+      ).selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.serverSelected);
       expect(result.track.id, 'no');
     });
@@ -549,7 +643,7 @@ void main() {
       final result = _svc(
         metadata: _meta(backend: MediaBackend.jellyfin),
         profile: _jellyfinProfile(defaultSubtitleLanguage: 'eng', subtitleMode: SubtitlePlaybackMode.none),
-      ).selectSubtitleTrack(tracks, null, null);
+      ).selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.profile);
       expect(result.track.id, 'no');
     });
@@ -563,7 +657,7 @@ void main() {
       final result = _svc(
         metadata: _meta(backend: MediaBackend.jellyfin),
         profile: _jellyfinProfile(defaultSubtitleLanguage: 'eng', subtitleMode: SubtitlePlaybackMode.onlyForced),
-      ).selectSubtitleTrack(tracks, null, null);
+      ).selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.profile);
       expect(result.track.id, '2');
     });
@@ -573,7 +667,7 @@ void main() {
       final result = _svc(
         metadata: _meta(backend: MediaBackend.jellyfin),
         profile: _jellyfinProfile(defaultSubtitleLanguage: 'eng', subtitleMode: SubtitlePlaybackMode.onlyForced),
-      ).selectSubtitleTrack(tracks, null, null);
+      ).selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.profile);
       expect(result.track.id, 'no');
     });
@@ -583,7 +677,7 @@ void main() {
       final result = _svc(
         metadata: _meta(backend: MediaBackend.jellyfin),
         profile: _jellyfinProfile(defaultSubtitleLanguage: 'eng', subtitleMode: SubtitlePlaybackMode.always),
-      ).selectSubtitleTrack(tracks, null, null);
+      ).selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.profile);
       expect(result.track.id, '2');
     });
@@ -593,7 +687,7 @@ void main() {
       final result = _svc(
         metadata: _meta(backend: MediaBackend.jellyfin),
         profile: _jellyfinProfile(defaultSubtitleLanguage: 'eng', subtitleMode: SubtitlePlaybackMode.always),
-      ).selectSubtitleTrack(tracks, null, null);
+      ).selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.profile);
       expect(result.track.id, '2');
     });
@@ -607,7 +701,7 @@ void main() {
           defaultSubtitleLanguage: 'eng',
           subtitleMode: SubtitlePlaybackMode.smart,
         ),
-      ).selectSubtitleTrack(tracks, null, _audio('A', lang: 'eng'));
+      ).selectSubtitleTrack(tracks, null, _audio('A', lang: 'eng'))!;
       expect(result.priority, TrackSelectionPriority.profile);
       expect(result.track.id, '2');
     });
@@ -621,30 +715,57 @@ void main() {
           defaultSubtitleLanguage: 'eng',
           subtitleMode: SubtitlePlaybackMode.smart,
         ),
-      ).selectSubtitleTrack(tracks, null, _audio('A', lang: 'jpn'));
+      ).selectSubtitleTrack(tracks, null, _audio('A', lang: 'jpn'))!;
       expect(result.priority, TrackSelectionPriority.profile);
       expect(result.track.id, '2');
     });
 
     test('Priority 3: default-flagged track when no Plex info', () {
       final tracks = [_sub('1', lang: 'eng'), _sub('2', lang: 'fre', isDefault: true)];
-      final result = _svc().selectSubtitleTrack(tracks, null, null);
+      final result = _svc().selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.defaultTrack);
       expect(result.track.id, '2');
     });
 
     test('Priority 4: off when no default and no info', () {
       final tracks = [_sub('1', lang: 'eng'), _sub('2', lang: 'fre')];
-      final result = _svc().selectSubtitleTrack(tracks, null, null);
+      final result = _svc().selectSubtitleTrack(tracks, null, null)!;
       expect(result.priority, TrackSelectionPriority.off);
       expect(result.track.id, 'no');
     });
 
     test('Priority 4: off when no available tracks at all', () {
-      final result = _svc().selectSubtitleTrack(const [], null, null);
+      final result = _svc().selectSubtitleTrack(const [], null, null)!;
       expect(result.priority, TrackSelectionPriority.off);
       expect(result.track.id, 'no');
     });
+
+    test('empty native track list remains undetermined when Plex advertises subtitles', () {
+      final info = _info(subs: [_plexSub(10, language: 'eng', selected: true)]);
+
+      final result = _svc(info: info).selectSubtitleTrack(const [], null, null);
+
+      expect(result, isNull);
+    });
+
+    test('empty native track list is also undetermined when Plex selected no subtitle', () {
+      final info = _info(subs: [_plexSub(10, language: 'eng')]);
+
+      final result = _svc(info: info).selectSubtitleTrack(const [], null, null);
+
+      expect(result, isNull);
+    });
+
+    test('selected keyed sidecar remains pending when only a same-language container has arrived', () {
+      final info = _info(
+        subs: [_plexSub(10, language: 'eng', selected: true, external: true, key: '/library/streams/10')],
+      );
+      final earlyContainer = _sub('20', lang: 'eng', isExternal: true, isContainer: true);
+
+      final result = _svc(info: info).selectSubtitleTrack([earlyContainer], null, null);
+
+      expect(result, isNull);
+    });
   });
 
   // ============================================================
@@ -691,6 +812,22 @@ void main() {
     });
   });
 
+  group('container-sidecar ordinal fallback', () {
+    final plexTracks = [_plexSub(40, index: 0), _plexSub(41, index: 1)];
+    final nativeTracks = [
+      _sub('2_0', isExternal: true, isContainer: true),
+      _sub('2_1', isExternal: true, isContainer: true),
+    ];
+
+    test('maps a metadata-free Plex stream to its container track', () {
+      expect(findMpvTrackForPlexSubtitle(plexTracks[1], nativeTracks, allPlexTracks: plexTracks), nativeTracks[1]);
+    });
+
+    test('maps a metadata-free container track back to its Plex stream', () {
+      expect(findPlexTrackForMpvSubtitle(nativeTracks[0], plexTracks, allMpvTracks: nativeTracks)?.id, 40);
+    });
+  });
+
   group('findPlexTrackForMpvAudio - same-language disambiguation', () {
     // Two French audio tracks differing only by channel count, titles null.
     final plexTracks = [