diff --git a/lib/screens/video_player/parts/build.dart b/lib/screens/video_player/parts/build.dart
index cc7e4128..c4cf0b8a 100644
--- a/lib/screens/video_player/parts/build.dart
+++ b/lib/screens/video_player/parts/build.dart
@@ -259,7 +259,7 @@ extension _VideoPlayerBuildMethods on VideoPlayerScreenState {
                         onNext: onNext,
                         onPrevious: onPrevious,
                         availableVersions: _availableVersions,
-                        selectedMediaIndex: widget.selectedMediaIndex,
+                        selectedMediaIndex: _effectiveSelectedMediaIndex,
                         selectedMediaSourceId: widget.selectedMediaSourceId,
                         selectedQualityPreset: _selectedQualityPreset,
                         serverSupportsTranscoding: _serverSupportsTranscoding,
diff --git a/lib/screens/video_player/parts/episode_navigation.dart b/lib/screens/video_player/parts/episode_navigation.dart
index 5d41738d..d3afae4e 100644
--- a/lib/screens/video_player/parts/episode_navigation.dart
+++ b/lib/screens/video_player/parts/episode_navigation.dart
@@ -163,8 +163,10 @@ extension _VideoPlayerEpisodeNavigationMethods on VideoPlayerScreenState {
 
     if (!_isCurrentPlaybackGeneration(playbackGeneration, currentPlayer)) return;
 
+    final requestedMediaIndex = _effectiveSelectedMediaIndex;
     _currentMetadata = episodeMetadata;
     VideoPlayerScreenState._activeId = episodeMetadata.id;
+    VideoPlayerScreenState._activeMediaIndex = requestedMediaIndex;
     _showPlayNextDialog = false;
     _autoPlayTimer?.cancel();
     _hasFirstFrame.value = false;
@@ -173,7 +175,7 @@ extension _VideoPlayerEpisodeNavigationMethods on VideoPlayerScreenState {
       final playbackResolver = PlaybackSourceResolver(serverManager: serverManager, database: database);
       final playbackContext = await playbackResolver.resolve(
         metadata: episodeMetadata,
-        selectedMediaIndex: widget.selectedMediaIndex,
+        selectedMediaIndex: requestedMediaIndex,
         selectedMediaSourceId: widget.selectedMediaSourceId,
         offlineLibraryMode: widget.isOffline,
         qualityPreset: _selectedQualityPreset,
@@ -198,6 +200,7 @@ extension _VideoPlayerEpisodeNavigationMethods on VideoPlayerScreenState {
       _playbackPlaySessionId = result.playSessionId;
       _playbackPlayMethod = result.playMethod;
       _selectedAudioStreamId = result.activeAudioStreamId;
+      _effectiveSelectedMediaIndex = result.selectedMediaIndex;
       if (result.fallbackReason != null && !_selectedQualityPreset.isOriginal) {
         if (mounted) {
           showErrorSnackBar(context, t.videoControls.transcodeUnavailableFallback);
diff --git a/lib/screens/video_player/parts/pip.dart b/lib/screens/video_player/parts/pip.dart
index cf5b0999..439ea8db 100644
--- a/lib/screens/video_player/parts/pip.dart
+++ b/lib/screens/video_player/parts/pip.dart
@@ -37,7 +37,7 @@ extension _VideoPlayerPipMethods on VideoPlayerScreenState {
       _videoFilterManager = VideoFilterManager(
         player: currentPlayer,
         availableVersions: _availableVersions,
-        selectedMediaIndex: widget.selectedMediaIndex,
+        selectedMediaIndex: _effectiveSelectedMediaIndex,
         initialBoxFitMode: settings.read(SettingsService.defaultBoxFitMode),
         onBoxFitModeChanged: (mode) => settings.write(SettingsService.defaultBoxFitMode, mode),
       );
diff --git a/lib/screens/video_player/parts/playback_start.dart b/lib/screens/video_player/parts/playback_start.dart
index 527a7092..23c1ef6d 100644
--- a/lib/screens/video_player/parts/playback_start.dart
+++ b/lib/screens/video_player/parts/playback_start.dart
@@ -185,6 +185,7 @@ extension _VideoPlayerPlaybackStartMethods on VideoPlayerScreenState {
           _selectedQualityPreset = TranscodeQualityPreset.original;
         }
       }
+      _effectiveSelectedMediaIndex = result.selectedMediaIndex;
       _playbackContext = playbackContext;
 
       // Primary refresh-rate path: when metadata provides FPS, Android players
diff --git a/lib/screens/video_player/parts/seeking.dart b/lib/screens/video_player/parts/seeking.dart
index 00a768b1..4f9082b0 100644
--- a/lib/screens/video_player/parts/seeking.dart
+++ b/lib/screens/video_player/parts/seeking.dart
@@ -65,7 +65,7 @@ extension _VideoPlayerSeekingMethods on VideoPlayerScreenState {
       final playbackService = PlaybackInitializationService(client: mediaClient, database: context.read<AppDatabase>());
       final result = await playbackService.getPlaybackData(
         metadata: replacementMetadata,
-        selectedMediaIndex: widget.selectedMediaIndex,
+        selectedMediaIndex: _effectiveSelectedMediaIndex,
         selectedMediaSourceId: widget.selectedMediaSourceId,
         preferOffline: false,
         qualityPreset: _selectedQualityPreset,
@@ -84,6 +84,7 @@ extension _VideoPlayerSeekingMethods on VideoPlayerScreenState {
       _playbackPlaySessionId = result.playSessionId;
       _playbackPlayMethod = result.playMethod;
       _selectedAudioStreamId = result.activeAudioStreamId;
+      _effectiveSelectedMediaIndex = result.selectedMediaIndex;
       _availableVersions = result.availableVersions;
       _currentMediaInfo = result.mediaInfo;
 
diff --git a/lib/screens/video_player_screen.dart b/lib/screens/video_player_screen.dart
index 8ecc0b77..0b4b6719 100644
--- a/lib/screens/video_player_screen.dart
+++ b/lib/screens/video_player_screen.dart
@@ -265,6 +265,7 @@ class VideoPlayerScreenState extends State<VideoPlayerScreen> with WidgetsBindin
   bool _isPhone = false;
   List<MediaVersion> _availableVersions = [];
   MediaSourceInfo? _currentMediaInfo;
+  late int _effectiveSelectedMediaIndex;
 
   // Transcode / quality state
   late TranscodeQualityPreset _selectedQualityPreset;
@@ -459,6 +460,7 @@ class VideoPlayerScreenState extends State<VideoPlayerScreen> with WidgetsBindin
     _currentMetadata = widget.metadata;
     _activeId = widget.metadata.id;
     _activeMediaIndex = widget.selectedMediaIndex;
+    _effectiveSelectedMediaIndex = widget.selectedMediaIndex;
 
     // Reused across quality/version/audio switches so the server-side
     // transcode session is preserved.
diff --git a/lib/services/jellyfin_client/parts/playback.dart b/lib/services/jellyfin_client/parts/playback.dart
index eb6f659f..b766045d 100644
--- a/lib/services/jellyfin_client/parts/playback.dart
+++ b/lib/services/jellyfin_client/parts/playback.dart
@@ -244,6 +244,7 @@ mixin _JellyfinPlaybackMethods on MediaServerCacheMixin {
       activeAudioStreamId: requestedAudioStreamId,
       playSessionId: playSessionId,
       playMethod: playMethod,
+      selectedMediaIndex: bundle.selectedSourceIndex,
     );
   }
 
@@ -384,6 +385,7 @@ mixin _JellyfinPlaybackMethods on MediaServerCacheMixin {
       chapters: chapters is List ? chapters : const [],
       container: source['Container'] as String?,
       selectedSourceId: source['Id'] as String?,
+      selectedSourceIndex: index,
       trickplay: raw['Trickplay'],
     );
   }
diff --git a/lib/services/jellyfin_playback_bundle.dart b/lib/services/jellyfin_playback_bundle.dart
index 05a2f07e..7b2865c1 100644
--- a/lib/services/jellyfin_playback_bundle.dart
+++ b/lib/services/jellyfin_playback_bundle.dart
@@ -30,6 +30,9 @@ class JellyfinPlaybackBundle {
   /// falls back to its first sorted source instead of the selected version.
   final String? selectedSourceId;
 
+  /// Effective source index after source-id matching and range clamping.
+  final int selectedSourceIndex;
+
   /// Item-level `Trickplay` manifest (raw JSON object). `null` when the
   /// server hasn't run trickplay extraction for this item.
   final Object? trickplay;
@@ -40,6 +43,7 @@ class JellyfinPlaybackBundle {
     required this.chapters,
     this.container,
     this.selectedSourceId,
+    this.selectedSourceIndex = 0,
     this.trickplay,
   });
 
diff --git a/lib/services/playback_initialization_service.dart b/lib/services/playback_initialization_service.dart
index f005592f..43ba5527 100644
--- a/lib/services/playback_initialization_service.dart
+++ b/lib/services/playback_initialization_service.dart
@@ -217,6 +217,7 @@ class PlaybackInitializationService {
       externalSubtitles: sidecarSubtitles,
       isOffline: true,
       playMethod: 'DirectPlay',
+      selectedMediaIndex: selectedMediaIndex,
     );
   }
 
diff --git a/lib/services/playback_initialization_types.dart b/lib/services/playback_initialization_types.dart
index d84a33d7..d48615d1 100644
--- a/lib/services/playback_initialization_types.dart
+++ b/lib/services/playback_initialization_types.dart
@@ -77,6 +77,9 @@ class PlaybackInitializationResult {
   /// expects one of `DirectPlay`, `DirectStream`, or `Transcode`.
   final String? playMethod;
 
+  /// Effective media version after backend clamping/fallback.
+  final int selectedMediaIndex;
+
   /// True when [videoUrl] points at a downloaded/local copy. This is a media
   /// source detail, not a statement about whether server reporting is possible.
   bool get usesLocalMedia => isOffline;
@@ -92,6 +95,7 @@ class PlaybackInitializationResult {
     this.activeAudioStreamId,
     this.playSessionId,
     this.playMethod,
+    this.selectedMediaIndex = 0,
   });
 }
 
diff --git a/lib/services/plex_client.dart b/lib/services/plex_client.dart
index 161e6a46..34c0ed1f 100644
--- a/lib/services/plex_client.dart
+++ b/lib/services/plex_client.dart
@@ -3284,6 +3284,7 @@ class PlexClient
             isTranscoding: true,
             activeAudioStreamId: resolvedAudioId,
             playMethod: 'Transcode',
+            selectedMediaIndex: data.selectedMediaIndex,
           );
         }
 
@@ -3302,6 +3303,7 @@ class PlexClient
           isTranscoding: false,
           fallbackReason: fallbackReason,
           playMethod: 'DirectPlay',
+          selectedMediaIndex: data.selectedMediaIndex,
         );
       }
 
@@ -3312,6 +3314,7 @@ class PlexClient
         externalSubtitles: _buildExternalSubtitles(data.mediaInfo),
         isOffline: false,
         playMethod: 'DirectPlay',
+        selectedMediaIndex: data.selectedMediaIndex,
       );
     } catch (e) {
       if (e is PlaybackException) rethrow;
diff --git a/lib/services/plex_playback_mapper.dart b/lib/services/plex_playback_mapper.dart
index c66b4d05..718041d7 100644
--- a/lib/services/plex_playback_mapper.dart
+++ b/lib/services/plex_playback_mapper.dart
@@ -2,6 +2,7 @@ import '../media/media_file_info.dart';
 import '../media/media_source_info.dart';
 import '../media/media_version.dart';
 import '../models/plex/plex_video_playback_data.dart';
+import '../utils/app_logger.dart';
 import '../utils/json_utils.dart';
 import '../utils/plex_url_helper.dart';
 import 'file_info_parser.dart';
@@ -25,6 +26,36 @@ int _firstPlayablePartIndex(MediaVersion version) {
   return playable >= 0 ? playable : 0;
 }
 
+void _logPartSelection(
+  List<Map> mediaList,
+  List<MediaVersion> versions,
+  int selectedMediaIndex,
+  int selectedPartIndex,
+) {
+  final candidateCount = mediaList.fold<int>(0, (count, media) => count + _mapList(media['Part']).length);
+  if (candidateCount <= 1) return;
+
+  final entries = <String>[];
+  for (var mediaIndex = 0; mediaIndex < mediaList.length; mediaIndex++) {
+    final partList = _mapList(mediaList[mediaIndex]['Part']);
+    for (var partIndex = 0; partIndex < partList.length; partIndex++) {
+      final part = partList[partIndex];
+      final versionPart = mediaIndex < versions.length && partIndex < versions[mediaIndex].parts.length
+          ? versions[mediaIndex].parts[partIndex]
+          : null;
+      final selected = mediaIndex == selectedMediaIndex && partIndex == selectedPartIndex ? ' selected' : '';
+      entries.add(
+        'Media[$mediaIndex].Part[$partIndex] '
+        'id=${part['id']} key=${part['key']} '
+        'exists=${versionPart?.exists} accessible=${versionPart?.accessible} '
+        'playable=${versionPart?.isPlayable}$selected',
+      );
+    }
+  }
+
+  appLogger.d('Plex playback part selection: ${entries.join('; ')}');
+}
+
 PlexVideoPlaybackData parsePlexVideoPlaybackDataFromJson(
   Map<String, dynamic>? metadataJson, {
   required String baseUrl,
@@ -64,6 +95,7 @@ PlexVideoPlaybackData parsePlexVideoPlaybackDataFromJson(
       if (partList.isNotEmpty) {
         selectedPartIndex = _firstPlayablePartIndex(availableVersions[mediaIndex]);
         if (selectedPartIndex < 0 || selectedPartIndex >= partList.length) selectedPartIndex = 0;
+        _logPartSelection(mediaList, availableVersions, selectedMediaIndex, selectedPartIndex);
         final part = partList[selectedPartIndex];
         final partKey = part['key']?.toString();
 
diff --git a/test/services/plex_playback_data_request_test.dart b/test/services/plex_playback_data_request_test.dart
index 3960ee12..13935dd6 100644
--- a/test/services/plex_playback_data_request_test.dart
+++ b/test/services/plex_playback_data_request_test.dart
@@ -5,10 +5,14 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:http/http.dart' as http;
 import 'package:http/testing.dart';
 import 'package:plezy/database/app_database.dart';
+import 'package:plezy/media/media_backend.dart';
+import 'package:plezy/media/media_item.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/plex/plex_config.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';
 import 'package:plezy/services/plex_client.dart';
 
@@ -107,11 +111,211 @@ void main() {
 
     expect(requests, hasLength(1));
     expect(requests.single.queryParameters['includeStreams'], '1');
+    expect(requests.single.queryParameters['checkFiles'], '1');
+    expect(requests.single.queryParameters.containsKey('checkFileAvailability'), isFalse);
     expect(data.mediaInfo?.subtitleTracks, hasLength(1));
     expect(data.mediaInfo?.subtitleTracks.single.id, 401);
     expect(data.mediaInfo?.subtitleTracks.single.selected, isTrue);
   });
 
+  test('playback uses metadata availability flags without probing part URLs', () async {
+    final requests = <http.Request>[];
+    final client = makeClient((request) async {
+      requests.add(request);
+      if (request.url.path != '/library/metadata/42') {
+        return http.Response('unexpected request', 500);
+      }
+
+      return http.Response(
+        jsonEncode({
+          'MediaContainer': {
+            'Metadata': [
+              {
+                'ratingKey': '42',
+                'type': 'movie',
+                'title': 'Movie',
+                'Media': [
+                  {
+                    'id': 7,
+                    'container': 'mkv',
+                    'Part': [
+                      {'id': 10, 'key': '/library/parts/10/file.mkv', 'exists': 0, 'accessible': 1},
+                      {'id': 20, 'key': '/library/parts/20/file.mkv', 'exists': 1, 'accessible': 1},
+                    ],
+                  },
+                ],
+              },
+            ],
+          },
+        }),
+        200,
+        headers: {'content-type': 'application/json'},
+      );
+    });
+    addTearDown(client.close);
+
+    final data = await client.getVideoPlaybackData('42');
+
+    expect(requests, hasLength(1));
+    expect(requests.single.url.queryParameters['checkFiles'], '1');
+    expect(requests.single.url.queryParameters.containsKey('checkFileAvailability'), isFalse);
+    expect(data.videoUrl, 'https://plex.example.com/library/parts/20/file.mkv?X-Plex-Token=token');
+    expect(data.selectedMediaIndex, 0);
+    expect(data.selectedPartIndex, 1);
+  });
+
+  test('latest server metadata overwrites cached playback media fields', () async {
+    final cache = PlexApiCache.instance;
+    await cache.put('server-id', '/library/metadata/42', {
+      'MediaContainer': {
+        'Metadata': [
+          {
+            'ratingKey': '42',
+            'type': 'movie',
+            'title': 'Playback title',
+            'Media': [
+              {
+                'id': 7,
+                'Part': [
+                  {
+                    'id': 99,
+                    'key': '/library/parts/99/file.mkv',
+                    'exists': true,
+                    'accessible': true,
+                    'Stream': [
+                      {'streamType': 1, 'id': 300, 'codec': 'h264'},
+                    ],
+                  },
+                ],
+              },
+            ],
+          },
+        ],
+      },
+    });
+
+    await cache.put('server-id', '/library/metadata/42', {
+      'MediaContainer': {
+        'Metadata': [
+          {
+            'ratingKey': '42',
+            'type': 'movie',
+            'title': 'Detail title',
+            'Media': [
+              {
+                'id': 7,
+                'Part': [
+                  {'id': 99, 'key': '/library/parts/99/weak.mkv'},
+                ],
+              },
+            ],
+          },
+        ],
+      },
+    });
+
+    final cached = await cache.get('server-id', '/library/metadata/42');
+    final metadata = (cached!['MediaContainer'] as Map<String, dynamic>)['Metadata'] as List<dynamic>;
+    final item = metadata.single as Map<String, dynamic>;
+    final media = item['Media'] as List<dynamic>;
+    final part = ((media.single as Map<String, dynamic>)['Part'] as List<dynamic>).single as Map<String, dynamic>;
+
+    expect(item['title'], 'Detail title');
+    expect(part['key'], '/library/parts/99/weak.mkv');
+    expect(part.containsKey('exists'), isFalse);
+    expect(part.containsKey('accessible'), isFalse);
+    expect(part.containsKey('Stream'), isFalse);
+  });
+
+  test('network failure falls back to lean cached playback metadata', () async {
+    await PlexApiCache.instance.put('server-id', '/library/metadata/42', {
+      'MediaContainer': {
+        'Metadata': [
+          {
+            'ratingKey': '42',
+            'type': 'movie',
+            'title': 'Movie',
+            'Media': [
+              {
+                'id': 7,
+                'Part': [
+                  {'id': 10, 'key': '/library/parts/10/stale.mkv'},
+                ],
+              },
+              {
+                'id': 8,
+                'Part': [
+                  {'id': 20, 'key': '/library/parts/20/current.mkv'},
+                ],
+              },
+            ],
+          },
+        ],
+      },
+    });
+    final requests = <http.Request>[];
+    final client = makeClient((request) async {
+      requests.add(request);
+      throw Exception('offline');
+    });
+    addTearDown(client.close);
+
+    final data = await client.getVideoPlaybackData('42');
+
+    expect(requests, hasLength(1));
+    expect(data.videoUrl, 'https://plex.example.com/library/parts/10/stale.mkv?X-Plex-Token=token');
+    expect(data.availableVersions, hasLength(2));
+  });
+
+  test('playback initialization exposes effective selected media index', () async {
+    final client = makeClient((request) async {
+      if (request.url.path != '/library/metadata/42') {
+        return http.Response('unexpected request', 500);
+      }
+
+      return http.Response(
+        jsonEncode({
+          'MediaContainer': {
+            'Metadata': [
+              {
+                'ratingKey': '42',
+                'type': 'movie',
+                'title': 'Movie',
+                'Media': [
+                  {
+                    'id': 7,
+                    'Part': [
+                      {'id': 10, 'key': '/library/parts/10/stale.mkv', 'exists': false, 'accessible': false},
+                    ],
+                  },
+                  {
+                    'id': 8,
+                    'Part': [
+                      {'id': 20, 'key': '/library/parts/20/current.mkv', 'exists': true, 'accessible': true},
+                    ],
+                  },
+                ],
+              },
+            ],
+          },
+        }),
+        200,
+        headers: {'content-type': 'application/json'},
+      );
+    });
+    addTearDown(client.close);
+
+    final result = await client.getPlaybackInitialization(
+      PlaybackInitializationOptions(
+        metadata: MediaItem(id: '42', backend: MediaBackend.plex, kind: MediaKind.movie, serverId: 'server-id'),
+        selectedMediaIndex: 0,
+      ),
+    );
+
+    expect(result.videoUrl, 'https://plex.example.com/library/parts/20/current.mkv?X-Plex-Token=token');
+    expect(result.selectedMediaIndex, 1);
+  });
+
   test('transcode subtitle sidecars only use real Plex stream keys', () {
     final client = makeClient((_) async => http.Response('not used', 500));
     addTearDown(client.close);
diff --git a/test/services/plex_playback_mapper_test.dart b/test/services/plex_playback_mapper_test.dart
index 1fda8e42..53c1a212 100644
--- a/test/services/plex_playback_mapper_test.dart
+++ b/test/services/plex_playback_mapper_test.dart
@@ -50,6 +50,37 @@ void main() {
       expect(result.selectedPartIndex, 0);
     });
 
+    test('falls back when first Plex media has unavailable part flags', () {
+      final result = parsePlexVideoPlaybackDataFromJson(
+        {
+          'Media': [
+            {
+              'id': 9773,
+              'videoResolution': '1080',
+              'Part': [
+                {'id': 9815, 'key': '/library/parts/9815/1774877382/file.mp4', 'accessible': false, 'exists': false},
+              ],
+            },
+            {
+              'id': 9766,
+              'videoResolution': '720',
+              'Part': [
+                {'id': 9808, 'key': '/library/parts/9808/1775431760/file.mp4', 'accessible': true, 'exists': true},
+              ],
+            },
+          ],
+        },
+        baseUrl: 'http://plex:32400',
+        token: 'tok',
+      );
+
+      expect(result.videoUrl, 'http://plex:32400/library/parts/9808/1775431760/file.mp4?X-Plex-Token=tok');
+      expect(result.selectedMediaIndex, 1);
+      expect(result.selectedPartIndex, 0);
+      expect(result.availableVersions.first.isPlayable, isFalse);
+      expect(result.availableVersions.last.isPlayable, isTrue);
+    });
+
     test('uses playable part when the first part is unavailable', () {
       final result = parsePlexVideoPlaybackDataFromJson(
         {