Merge branch 'develop' into fix/subtitle-track-selection

The track-building effect in VideoContext reruns once api?.basePath and
isCurrentSubImageBased settle. An earlier async run could resolve after a
rerun and overwrite subtitleTracks/audioTracks with setTrack callbacks bound
to a stale `api`, breaking external-subtitle identity matching.

Add a cancellation token and route every state commit through guarded
committers so all six commit points (offline-transcoded audio/subs,
burned-in, and the online audio/subs paths) drop writes from a dead run,
plus bail out right after the awaited getAudioTracks when cancelled.

app/(auth)/player/direct-player.tsx

@@ -56,8 +56,8 @@ import { getDefaultPlaySettings } from "@/utils/jellyfin/getDefaultPlaySettings"
 import { getPrimaryImageUrl } from "@/utils/jellyfin/image/getPrimaryImageUrl";
 import { getStreamUrl } from "@/utils/jellyfin/media/getStreamUrl";
 import {
+  applyMpvSubtitleSelection,
   getMpvAudioId,
-  getMpvSubtitleId,
 } from "@/utils/jellyfin/subtitleUtils";
 import { writeToLog } from "@/utils/log";
 import { msToTicks, ticksToSeconds } from "@/utils/time";
@@ -639,12 +639,9 @@ export default function DirectPlayerPage() {
       ).map((s) => s.DeliveryUrl!);
     }
 
-    // Calculate track IDs for initial selection
-    const initialSubtitleId = getMpvSubtitleId(
-      mediaSource,
-      subtitleIndex,
-      isTranscoding,
-    );
+    // Audio maps positionally (audio tracks aren't reordered or hidden like
+    // subtitles). The subtitle selection is applied later, once MPV's real track
+    // list is known — see applySubtitleSelection / onTracksReady.
     const initialAudioId = getMpvAudioId(
       mediaSource,
       audioIndex,
@@ -662,7 +659,6 @@ export default function DirectPlayerPage() {
       url: stream.url,
       startPosition: startPos,
       autoplay: true,
-      initialSubtitleId,
       initialAudioId,
       // Pass cache/buffer settings from user preferences
       cacheConfig: {
@@ -710,7 +706,6 @@ export default function DirectPlayerPage() {
     playbackPositionFromUrl,
     api?.basePath,
     api?.accessToken,
-    subtitleIndex,
     audioIndex,
     offline,
     settings.mpvCacheEnabled,
@@ -908,30 +903,41 @@ export default function DirectPlayerPage() {
   );
 
   // TV subtitle track change handler
+  /**
+   * Resolve a Jellyfin subtitle index against MPV's *real* track list and apply
+   * it. Identity-based (external by filename, embedded by language/title) so it
+   * stays correct across external/embedded reordering and server-hidden embedded
+   * subs — unlike positional mapping. Reused for initial selection (onTracksReady,
+   * fired again after each external sub-add) and runtime changes.
+   */
+  const applySubtitleSelection = useCallback(
+    async (jellyfinSubtitleIndex: number) => {
+      const subtitleStreams = stream?.mediaSource?.MediaStreams?.filter(
+        (s) => s.Type === "Subtitle",
+      );
+      await applyMpvSubtitleSelection(videoRef.current, {
+        subtitleStreams,
+        jellyfinSubtitleIndex,
+        // The exact URL each external sub was loaded into MPV with — mirrors the
+        // externalSubtitles array built in videoSource (online: basePath +
+        // DeliveryUrl, offline: local DeliveryUrl).
+        getExpectedExternalUrl: (s) => {
+          if (!s.DeliveryUrl) return undefined;
+          if (offline) return s.DeliveryUrl;
+          return api?.basePath ? `${api.basePath}${s.DeliveryUrl}` : undefined;
+        },
+      });
+    },
+    [stream?.mediaSource, offline, api?.basePath],
+  );
+
+  // TV/mobile subtitle track change handler
   const handleSubtitleIndexChange = useCallback(
     async (index: number) => {
       setCurrentSubtitleIndex(index);
-
-      // Check if we're transcoding
-      const isTranscoding = Boolean(stream?.mediaSource?.TranscodingUrl);
-
-      if (index === -1) {
-        // Disable subtitles
-        await videoRef.current?.disableSubtitles?.();
-      } else {
-        // Convert Jellyfin index to MPV track ID
-        const mpvTrackId = getMpvSubtitleId(
-          stream?.mediaSource,
-          index,
-          isTranscoding,
-        );
-
-        if (mpvTrackId !== undefined && mpvTrackId !== -1) {
-          await videoRef.current?.setSubtitleTrack?.(mpvTrackId);
-        }
-      }
+      await applySubtitleSelection(index);
     },
-    [stream?.mediaSource],
+    [applySubtitleSelection],
   );
 
   // Technical info toggle handler
@@ -1296,6 +1302,10 @@ export default function DirectPlayerPage() {
                 }}
                 onTracksReady={() => {
                   setTracksReady(true);
+                  // Fired after embedded tracks enumerate and again after each
+                  // external sub-add; re-resolve so the final fire (full track
+                  // list) selects the right track by identity.
+                  void applySubtitleSelection(currentSubtitleIndex);
                 }}
               />
               {!hasPlaybackStarted && (

components/ItemContent.tv.tsx

@@ -56,6 +56,7 @@ import { useSettings } from "@/utils/atoms/settings";
 import type { TVOptionItem } from "@/utils/atoms/tvOptionModal";
 import { getLogoImageUrlById } from "@/utils/jellyfin/image/getLogoImageUrlById";
 import { getPrimaryImageUrlById } from "@/utils/jellyfin/image/getPrimaryImageUrlById";
+import { compareTracksForMenu } from "@/utils/jellyfin/subtitleUtils";
 import { formatDuration, runtimeTicksToMinutes } from "@/utils/time";
 
 const { width: SCREEN_WIDTH, height: SCREEN_HEIGHT } = Dimensions.get("window");
@@ -232,12 +233,13 @@ export const ItemContentTV: React.FC<ItemContentTVProps> = React.memo(
       return streams ?? [];
     }, [selectedOptions?.mediaSource]);
 
-    // Get available subtitle tracks (raw MediaStream[] for label lookup)
+    // Get available subtitle tracks (raw MediaStream[] for label lookup),
+    // ordered like jellyfin-web (embedded first, externals last, forced/default up).
     const subtitleStreams = useMemo(() => {
       const streams = selectedOptions?.mediaSource?.MediaStreams?.filter(
         (s) => s.Type === "Subtitle",
       );
-      return streams ?? [];
+      return streams ? [...streams].sort(compareTracksForMenu) : [];
     }, [selectedOptions?.mediaSource]);
 
     // Store handleSubtitleChange in a ref for stable callback reference
@@ -411,11 +413,13 @@ export const ItemContentTV: React.FC<ItemContentTVProps> = React.memo(
             )
           : freshItem.MediaSources?.[0];
 
-        // Get subtitle streams from the fresh data
-        const streams =
-          mediaSource?.MediaStreams?.filter(
+        // Get subtitle streams from the fresh data, ordered like jellyfin-web
+        // (embedded first, externals last) — same as the initial list.
+        const streams = [
+          ...(mediaSource?.MediaStreams?.filter(
             (s: MediaStream) => s.Type === "Subtitle",
-          ) ?? [];
+          ) ?? []),
+        ].sort(compareTracksForMenu);
 
         // Convert to Track[] with setTrack callbacks
         const tracks: Track[] = streams.map((stream) => ({

components/MediaSourceButton.tsx

@@ -7,6 +7,7 @@ import { useCallback, useEffect, useMemo, useState } from "react";
 import { useTranslation } from "react-i18next";
 import { ActivityIndicator, TouchableOpacity, View } from "react-native";
 import type { ThemeColors } from "@/hooks/useImageColorsReturn";
+import { compareTracksForMenu } from "@/utils/jellyfin/subtitleUtils";
 import { BITRATES } from "./BitRateSheet";
 import type { SelectedOptions } from "./ItemContent";
 import { type OptionGroup, PlatformDropdown } from "./PlatformDropdown";
@@ -63,9 +64,12 @@ export const MediaSourceButton: React.FC<Props> = ({
 
   const subtitleStreams = useMemo(
     () =>
-      selectedOptions.mediaSource?.MediaStreams?.filter(
-        (x) => x.Type === "Subtitle",
-      ) || [],
+      // Order like jellyfin-web (embedded first, externals last, forced/default up).
+      [
+        ...(selectedOptions.mediaSource?.MediaStreams?.filter(
+          (x) => x.Type === "Subtitle",
+        ) || []),
+      ].sort(compareTracksForMenu),
     [selectedOptions.mediaSource],
   );
 

components/SubtitleTrackSelector.tsx

@@ -2,6 +2,7 @@ import type { MediaSourceInfo } from "@jellyfin/sdk/lib/generated-client/models"
 import { useMemo, useState } from "react";
 import { useTranslation } from "react-i18next";
 import { Platform, TouchableOpacity, View } from "react-native";
+import { compareTracksForMenu } from "@/utils/jellyfin/subtitleUtils";
 import { tc } from "@/utils/textTools";
 import { Text } from "./common/Text";
 import { type OptionGroup, PlatformDropdown } from "./PlatformDropdown";
@@ -22,7 +23,9 @@ export const SubtitleTrackSelector: React.FC<Props> = ({
   const [open, setOpen] = useState(false);
 
   const subtitleStreams = useMemo(() => {
-    return source?.MediaStreams?.filter((x) => x.Type === "Subtitle");
+    const subs = source?.MediaStreams?.filter((x) => x.Type === "Subtitle");
+    // Order like jellyfin-web (embedded first, externals last, forced/default up).
+    return subs ? [...subs].sort(compareTracksForMenu) : subs;
   }, [source]);
 
   const selectedSubtitleSteam = useMemo(

components/video-player/controls/Controls.tv.tsx

@@ -51,6 +51,7 @@ import { useOfflineMode } from "@/providers/OfflineModeProvider";
 import { useSettings } from "@/utils/atoms/settings";
 import type { TVOptionItem } from "@/utils/atoms/tvOptionModal";
 import { getDefaultPlaySettings } from "@/utils/jellyfin/getDefaultPlaySettings";
+import { compareTracksForMenu } from "@/utils/jellyfin/subtitleUtils";
 import { formatTimeString, msToTicks, ticksToMs } from "@/utils/time";
 import { CONTROLS_CONSTANTS } from "./constants";
 import { useVideoContext } from "./contexts/VideoContext";
@@ -317,8 +318,10 @@ export const Controls: FC<Props> = ({
     try {
       const streams = (await onRefreshSubtitleTracks?.()) ?? [];
       // Skip streams without a real index: `?? -1` would alias them to the
-      // "disable subtitles" sentinel and mis-route selection.
-      return streams
+      // "disable subtitles" sentinel and mis-route selection. Order like
+      // jellyfin-web (embedded first, externals last, forced/default up).
+      return [...streams]
+        .sort(compareTracksForMenu)
         .filter((stream) => typeof stream.Index === "number")
         .map((stream) => {
           const index = stream.Index as number;

components/video-player/controls/TVSubtitleSheet.tsx

@@ -33,6 +33,7 @@ import {
   type SubtitleSearchResult,
   useRemoteSubtitles,
 } from "@/hooks/useRemoteSubtitles";
+import { compareTracksForMenu } from "@/utils/jellyfin/subtitleUtils";
 import { COMMON_SUBTITLE_LANGUAGES } from "@/utils/opensubtitles/api";
 
 interface TVSubtitleSheetProps {
@@ -96,13 +97,19 @@ export const TVSubtitleSheet: React.FC<TVSubtitleSheetProps> = ({
   const overlayOpacity = useRef(new Animated.Value(0)).current;
   const sheetTranslateY = useRef(new Animated.Value(300)).current;
 
+  // Order like jellyfin-web (embedded first, externals last, forced/default up).
+  const sortedTracks = useMemo(
+    () => [...subtitleTracks].sort(compareTracksForMenu),
+    [subtitleTracks],
+  );
+
   const initialSelectedTrackIndex = useMemo(() => {
     if (currentSubtitleIndex === -1) return 0;
-    const trackIdx = subtitleTracks.findIndex(
+    const trackIdx = sortedTracks.findIndex(
       (t) => t.Index === currentSubtitleIndex,
     );
     return trackIdx >= 0 ? trackIdx + 1 : 0;
-  }, [subtitleTracks, currentSubtitleIndex]);
+  }, [sortedTracks, currentSubtitleIndex]);
 
   useEffect(() => {
     if (visible) {
@@ -215,7 +222,7 @@ export const TVSubtitleSheet: React.FC<TVSubtitleSheetProps> = ({
       value: -1,
       selected: currentSubtitleIndex === -1,
     };
-    const options = subtitleTracks.map((track) => ({
+    const options = sortedTracks.map((track) => ({
       label:
         track.DisplayTitle || `${track.Language || "Unknown"} (${track.Codec})`,
       sublabel: track.Codec?.toUpperCase(),
@@ -223,7 +230,7 @@ export const TVSubtitleSheet: React.FC<TVSubtitleSheetProps> = ({
       selected: track.Index === currentSubtitleIndex,
     }));
     return [noneOption, ...options];
-  }, [subtitleTracks, currentSubtitleIndex, t]);
+  }, [sortedTracks, currentSubtitleIndex, t]);
 
   if (!visible) return null;
 

components/video-player/controls/contexts/VideoContext.tsx

@@ -23,32 +23,29 @@
  *    - Used to report playback state to Jellyfin server
  *    - Value of -1 means disabled/none
  *
- * 2. MPV INDEX (track.mpvIndex)
- *    - MPV's internal track ID
- *    - MPV orders tracks as: [all embedded, then all external]
- *    - IDs: 1..embeddedCount for embedded, embeddedCount+1.. for external
- *    - Value of -1 means track needs replacePlayer() (e.g., burned-in sub)
+ * 2. PLAYER TRACK (selected by IDENTITY, not position)
+ *    - Selection resolves the server Index against MPV's REAL track list via
+ *      applyMpvSubtitleSelection: externals matched by external-filename,
+ *      embedded by language/title. `track.mpvIndex` is no longer used to select
+ *      (kept -1) — positional mapping mis-selected when externals/embedded were
+ *      reordered or the server hid embedded subs (#954 et al.).
  *
  * ============================================================================
  * SUBTITLE HANDLING
  * ============================================================================
  *
- * Embedded (DeliveryMethod.Embed):
- *   - Already in MPV's track list
- *   - Select via setSubtitleTrack(mpvId)
- *
- * External (DeliveryMethod.External):
- *   - Loaded into MPV on video start
- *   - Select via setSubtitleTrack(embeddedCount + externalPosition + 1)
+ * Embedded & External:
+ *   - Selected via applyMpvSubtitleSelection (identity match against the live
+ *     track list). Menu order matches jellyfin-web (compareTracksForMenu:
+ *     embedded first, externals last, forced/default float up).
  *
  * Image-based during transcoding:
- *   - Burned into video by Jellyfin, not in MPV
- *   - Requires replacePlayer() to change
+ *   - Burned into video by Jellyfin, not in MPV → replacePlayer() to change.
  */
 
-import { SubtitleDeliveryMethod } from "@jellyfin/sdk/lib/generated-client";
 import { File } from "expo-file-system";
 import { useLocalSearchParams } from "expo-router";
+import { useAtomValue } from "jotai";
 import type React from "react";
 import {
   createContext,
@@ -61,9 +58,14 @@ import {
 import { Platform } from "react-native";
 import useRouter from "@/hooks/useAppRouter";
 import type { MpvAudioTrack } from "@/modules";
+import { apiAtom } from "@/providers/JellyfinProvider";
 import { useOfflineMode } from "@/providers/OfflineModeProvider";
 import { getSubtitlesForItem } from "@/utils/atoms/downloadedSubtitles";
-import { isImageBasedSubtitle } from "@/utils/jellyfin/subtitleUtils";
+import {
+  applyMpvSubtitleSelection,
+  compareTracksForMenu,
+  isImageBasedSubtitle,
+} from "@/utils/jellyfin/subtitleUtils";
 import type { Track } from "../types";
 import { usePlayerContext, usePlayerControls } from "./PlayerContext";
 
@@ -87,6 +89,7 @@ export const VideoProvider: React.FC<{ children: ReactNode }> = ({
   const { tracksReady, mediaSource, downloadedItem } = usePlayerContext();
   const playerControls = usePlayerControls();
   const offline = useOfflineMode();
+  const api = useAtomValue(apiAtom);
   const router = useRouter();
 
   const { itemId, audioIndex, bitrateValue, subtitleIndex, playbackPosition } =
@@ -141,6 +144,19 @@ export const VideoProvider: React.FC<{ children: ReactNode }> = ({
   useEffect(() => {
     if (!tracksReady) return;
 
+    // Guard every state commit against stale runs: api?.basePath /
+    // isCurrentSubImageBased can flip mid-run and restart this effect, and an
+    // earlier async run (which captured an old `api`) must not finish later and
+    // overwrite the fresh track list with callbacks bound to stale closures.
+    // The cleanup flips `cancelled`, so any late commit from a dead run is dropped.
+    let cancelled = false;
+    const commitSubtitleTracks = (next: Track[]) => {
+      if (!cancelled) setSubtitleTracks(next);
+    };
+    const commitAudioTracks = (next: Track[]) => {
+      if (!cancelled) setAudioTracks(next);
+    };
+
     const fetchTracks = async () => {
       // Check if this is offline transcoded content
       // For transcoded offline content, only ONE audio track exists in the file
@@ -166,10 +182,10 @@ export const VideoProvider: React.FC<{ children: ReactNode }> = ({
               },
             },
           ];
-          setAudioTracks(audio);
+          commitAudioTracks(audio);
         } else {
           // Fallback: show no audio tracks if the stored track wasn't found
-          setAudioTracks([]);
+          commitAudioTracks([]);
         }
 
         // For subtitles in transcoded offline content:
@@ -179,6 +195,24 @@ export const VideoProvider: React.FC<{ children: ReactNode }> = ({
           downloadedItem.userData.subtitleStreamIndex;
         const subs: Track[] = [];
 
+        // If an IMAGE subtitle was burned into the transcoded download it's in the
+        // video pixels — it can't be turned off or swapped. Show only that entry
+        // instead of advertising "Disable"/text controls that can't affect it.
+        const burnedInSub = allSubs.find(
+          (s) => s.Index === downloadedSubtitleIndex,
+        );
+        if (burnedInSub && isImageBasedSubtitle(burnedInSub)) {
+          commitSubtitleTracks([
+            {
+              name: `${burnedInSub.DisplayTitle || "Unknown"} (burned in)`,
+              index: burnedInSub.Index ?? -1,
+              mpvIndex: -1,
+              setTrack: () => {},
+            },
+          ]);
+          return;
+        }
+
         // Add "Disable" option
         subs.push({
           name: "Disable",
@@ -190,123 +224,82 @@ export const VideoProvider: React.FC<{ children: ReactNode }> = ({
           },
         });
 
-        // For text-based subs, they should still be available in the file
-        let subIdx = 1;
-        for (const sub of allSubs) {
-          if (sub.IsTextSubtitleStream) {
+        // Text subs are muxed into the transcoded file and switchable; resolve by
+        // identity against MPV's real track list (same as online). Order matches web.
+        // Image subs aren't in the transcoded file (only the burned one was, handled
+        // above), so skip them here.
+        for (const sub of [...allSubs].sort(compareTracksForMenu)) {
+          if (!isImageBasedSubtitle(sub)) {
             subs.push({
               name: sub.DisplayTitle || "Unknown",
               index: sub.Index ?? -1,
-              mpvIndex: subIdx,
+              mpvIndex: -1,
               setTrack: () => {
-                playerControls.setSubtitleTrack(subIdx);
-                router.setParams({ subtitleIndex: String(sub.Index) });
-              },
-            });
-            subIdx++;
-          } else if (sub.Index === downloadedSubtitleIndex) {
-            // This image-based sub was burned in - show it but indicate it's active
-            subs.push({
-              name: `${sub.DisplayTitle || "Unknown"} (burned in)`,
-              index: sub.Index ?? -1,
-              mpvIndex: -1, // Can't be changed
-              setTrack: () => {
-                // Already burned in, just update params
                 router.setParams({ subtitleIndex: String(sub.Index) });
+                void applyMpvSubtitleSelection(playerControls, {
+                  subtitleStreams: allSubs,
+                  jellyfinSubtitleIndex: sub.Index ?? -1,
+                  getExpectedExternalUrl: (s) => {
+                    if (!s.DeliveryUrl) return undefined;
+                    if (offline) return s.DeliveryUrl;
+                    return api?.basePath
+                      ? `${api.basePath}${s.DeliveryUrl}`
+                      : undefined;
+                  },
+                });
               },
             });
           }
         }
 
-        setSubtitleTracks(subs.sort((a, b) => a.index - b.index));
+        commitSubtitleTracks(subs);
         return;
       }
 
       // MPV track handling
       const audioData = await playerControls.getAudioTracks().catch(() => null);
+      if (cancelled) return;
       const playerAudio = (audioData as MpvAudioTrack[]) ?? [];
 
-      // Separate embedded vs external subtitles from Jellyfin's list
-      // MPV orders tracks as: [all embedded, then all external]
-      const embeddedSubs = allSubs.filter(
-        (s) => s.DeliveryMethod === SubtitleDeliveryMethod.Embed,
-      );
-      const externalSubs = allSubs.filter(
-        (s) => s.DeliveryMethod === SubtitleDeliveryMethod.External,
-      );
-
-      // Count embedded subs that will be in MPV
-      // (excludes image-based subs during transcoding as they're burned in)
-      const embeddedInPlayer = embeddedSubs.filter(
-        (s) => !isTranscoding || !isImageBasedSubtitle(s),
-      );
-
       const subs: Track[] = [];
 
-      // Process all Jellyfin subtitles
-      for (const sub of allSubs) {
-        const isEmbedded = sub.DeliveryMethod === SubtitleDeliveryMethod.Embed;
-        const isExternal =
-          sub.DeliveryMethod === SubtitleDeliveryMethod.External;
-
-        // For image-based subs during transcoding, need to refresh player
-        if (isTranscoding && isImageBasedSubtitle(sub)) {
-          subs.push({
-            name: sub.DisplayTitle || "Unknown",
-            index: sub.Index ?? -1,
-            mpvIndex: -1,
-            setTrack: () => {
-              replacePlayer({ subtitleIndex: String(sub.Index) });
-            },
-          });
-          continue;
-        }
-
-        // Calculate MPV track ID based on type
-        // MPV IDs: [1..embeddedCount] for embedded, [embeddedCount+1..] for external
-        let mpvId = -1;
-
-        if (isEmbedded) {
-          // Find position among embedded subs that are in player
-          const embeddedPosition = embeddedInPlayer.findIndex(
-            (s) => s.Index === sub.Index,
-          );
-          if (embeddedPosition !== -1) {
-            mpvId = embeddedPosition + 1; // 1-based ID
-          }
-        } else if (isExternal) {
-          // Find position among external subs, offset by embedded count
-          const externalPosition = externalSubs.findIndex(
-            (s) => s.Index === sub.Index,
-          );
-          if (externalPosition !== -1) {
-            mpvId = embeddedInPlayer.length + externalPosition + 1;
-          }
-        }
+      // Process all Jellyfin subtitles. Selection resolves against MPV's real
+      // track list by identity (applyMpvSubtitleSelection) — never positional
+      // index math, which mis-selects across external/embedded reordering and
+      // server-hidden embedded subs (#954/#1690/#618/#1467/#976/#1451).
+      // Order matches jellyfin-web (embedded first, externals last, forced/default up).
+      for (const sub of [...allSubs].sort(compareTracksForMenu)) {
+        // Image-based subs during transcoding are burned into the video by the
+        // server; both switching TO one and switching AWAY from a currently
+        // active one require a player refresh (re-transcode), not a track change.
+        const needsReplace =
+          isTranscoding &&
+          (isImageBasedSubtitle(sub) || isCurrentSubImageBased);
 
         subs.push({
           name: sub.DisplayTitle || "Unknown",
           index: sub.Index ?? -1,
-          mpvIndex: mpvId,
+          mpvIndex: -1,
           setTrack: () => {
-            // Transcoding + switching to/from image-based sub
-            if (
-              isTranscoding &&
-              (isImageBasedSubtitle(sub) || isCurrentSubImageBased)
-            ) {
+            if (needsReplace) {
               replacePlayer({ subtitleIndex: String(sub.Index) });
               return;
             }
-
-            // Direct switch in player
-            if (mpvId !== -1) {
-              playerControls.setSubtitleTrack(mpvId);
-              router.setParams({ subtitleIndex: String(sub.Index) });
-              return;
-            }
-
-            // Fallback - refresh player
-            replacePlayer({ subtitleIndex: String(sub.Index) });
+            router.setParams({ subtitleIndex: String(sub.Index) });
+            void applyMpvSubtitleSelection(playerControls, {
+              subtitleStreams: allSubs,
+              jellyfinSubtitleIndex: sub.Index ?? -1,
+              // Mirror how external subs are loaded into MPV (online: basePath +
+              // DeliveryUrl, offline: local DeliveryUrl) so identity matching by
+              // external-filename lines up.
+              getExpectedExternalUrl: (s) => {
+                if (!s.DeliveryUrl) return undefined;
+                if (offline) return s.DeliveryUrl;
+                return api?.basePath
+                  ? `${api.basePath}${s.DeliveryUrl}`
+                  : undefined;
+              },
+            });
           },
         });
       }
@@ -374,12 +367,29 @@ export const VideoProvider: React.FC<{ children: ReactNode }> = ({
         }
       }
 
-      setSubtitleTracks(subs.sort((a, b) => a.index - b.index));
-      setAudioTracks(audio);
+      // Already in jellyfin-web order (sorted iteration above); "Disable" stays
+      // at the front (unshifted), local downloaded subs at the end.
+      commitSubtitleTracks(subs);
+      commitAudioTracks(audio);
     };
 
     fetchTracks();
-  }, [tracksReady, mediaSource, offline, downloadedItem, itemId]);
+    return () => {
+      cancelled = true;
+    };
+    // api?.basePath: setTrack builds external-sub URLs from it — rebuild once the
+    // API is ready so online externals don't resolve with undefined.
+    // isCurrentSubImageBased: setTrack closes over it for the transcode replacePlayer
+    // decision — rebuild when it flips so we refresh the stream when we should.
+  }, [
+    tracksReady,
+    mediaSource,
+    offline,
+    downloadedItem,
+    itemId,
+    api?.basePath,
+    isCurrentSubImageBased,
+  ]);
 
   return (
     <VideoContext.Provider value={{ subtitleTracks, audioTracks }}>

modules/mpv-player/android/src/main/java/expo/modules/mpvplayer/MPVLayerRenderer.kt

@@ -535,6 +535,17 @@ class MPVLayerRenderer(private val context: Context) : MPVLib.EventObserver {
 
             mpv?.getPropertyString("track-list/$i/title")?.let { track["title"] = it }
             mpv?.getPropertyString("track-list/$i/lang")?.let { track["lang"] = it }
+            mpv?.getPropertyString("track-list/$i/codec")?.let { track["codec"] = it }
+
+            // Identity fields used to map a Jellyfin subtitle to the real track
+            // (instead of fragile positional counting). `external` + `external-filename`
+            // uniquely identify a sub-added sidecar; `ff-index` aids embedded matching.
+            val external = mpv?.getPropertyBoolean("track-list/$i/external") ?: false
+            track["external"] = external
+            mpv?.getPropertyString("track-list/$i/external-filename")?.let {
+                track["externalFilename"] = it
+            }
+            mpv?.getPropertyInt("track-list/$i/ff-index")?.let { track["ffIndex"] = it }
 
             val selected = mpv?.getPropertyBoolean("track-list/$i/selected") ?: false
             track["selected"] = selected

modules/mpv-player/ios/MPVLayerRenderer.swift

@@ -771,11 +771,31 @@ final class MPVLayerRenderer {
                 track["lang"] = lang
             }
 
+            if let codec = getStringProperty(handle: handle, name: "track-list/\(i)/codec") {
+                track["codec"] = codec
+            }
+
+            // Identity fields used to map a Jellyfin subtitle to the real track
+            // (instead of fragile positional counting). `external` + `external-filename`
+            // uniquely identify a sub-added sidecar; `ff-index` aids embedded matching.
+            var external: Int32 = 0
+            getProperty(handle: handle, name: "track-list/\(i)/external", format: MPV_FORMAT_FLAG, value: &external)
+            track["external"] = external != 0
+
+            if let extFilename = getStringProperty(handle: handle, name: "track-list/\(i)/external-filename") {
+                track["externalFilename"] = extFilename
+            }
+
+            var ffIndex: Int64 = 0
+            if getProperty(handle: handle, name: "track-list/\(i)/ff-index", format: MPV_FORMAT_INT64, value: &ffIndex) >= 0 {
+                track["ffIndex"] = Int(ffIndex)
+            }
+
             var selected: Int32 = 0
             getProperty(handle: handle, name: "track-list/\(i)/selected", format: MPV_FORMAT_FLAG, value: &selected)
             track["selected"] = selected != 0
 
-            Logger.shared.log("getSubtitleTracks: found sub track id=\(trackId), title=\(track["title"] ?? "none"), lang=\(track["lang"] ?? "none")", type: "Info")
+            Logger.shared.log("getSubtitleTracks: found sub track id=\(trackId), title=\(track["title"] ?? "none"), lang=\(track["lang"] ?? "none"), external=\(external != 0)", type: "Info")
             tracks.append(track)
         }
         

modules/mpv-player/src/MpvPlayer.types.ts

@@ -141,6 +141,14 @@ export type SubtitleTrack = {
   id: number;
   title?: string;
   lang?: string;
+  /** Subtitle codec (mpv `codec`), e.g. "subrip", "ass", "hdmv_pgs_subtitle". */
+  codec?: string;
+  /** True if loaded from a separate file via `sub-add` (mpv `external`). */
+  external?: boolean;
+  /** For external tracks: the exact URL/path it was loaded from (mpv `external-filename`). */
+  externalFilename?: string;
+  /** FFmpeg stream index (mpv `ff-index`); not guaranteed for non-lavf demuxers. */
+  ffIndex?: number;
   selected?: boolean;
 };
 

utils/jellyfin/subtitleUtils.test.ts

@@ -0,0 +1,221 @@
+import { describe, expect, test } from "bun:test";
+import type {
+  MediaStream,
+  SubtitleDeliveryMethod,
+} from "@jellyfin/sdk/lib/generated-client";
+import {
+  compareTracksForMenu,
+  isExternalSubtitle,
+  type PlayerSubtitleTrack,
+  resolveSubtitleTrack,
+} from "@/utils/jellyfin/subtitleUtils";
+
+// String-enum values as typed literals — avoids a runtime SDK import (see subtitleUtils.ts).
+const External = "External" as SubtitleDeliveryMethod;
+const Embed = "Embed" as SubtitleDeliveryMethod;
+
+// --- fixtures --------------------------------------------------------------
+
+const sub = (o: Partial<MediaStream> & { Index: number }): MediaStream =>
+  ({ Type: "Subtitle", ...o }) as MediaStream;
+
+const ext = (Index: number, o: Partial<MediaStream> = {}): MediaStream =>
+  sub({
+    Index,
+    DeliveryMethod: External,
+    IsExternal: true,
+    DeliveryUrl: `/sub/${Index}.srt`,
+    ...o,
+  });
+
+const emb = (Index: number, o: Partial<MediaStream> = {}): MediaStream =>
+  sub({ Index, DeliveryMethod: Embed, ...o });
+
+const track = (o: PlayerSubtitleTrack): PlayerSubtitleTrack => o;
+
+// Mirror direct-player.tsx online URL builder.
+const urlBuilder =
+  (base: string) =>
+  (s: MediaStream): string | undefined =>
+    s.DeliveryUrl ? `${base}${s.DeliveryUrl}` : undefined;
+
+const resolve = (
+  streams: MediaStream[],
+  index: number | undefined,
+  player: PlayerSubtitleTrack[],
+  getExpectedExternalUrl = urlBuilder("http://srv"),
+) =>
+  resolveSubtitleTrack({
+    subtitleStreams: streams,
+    jellyfinSubtitleIndex: index,
+    playerTracks: player,
+    getExpectedExternalUrl,
+  });
+
+// --- tests -----------------------------------------------------------------
+
+describe("isExternalSubtitle", () => {
+  test("true for External delivery or the IsExternal flag, not a bare DeliveryUrl", () => {
+    expect(isExternalSubtitle(ext(0))).toBe(true);
+    expect(isExternalSubtitle(sub({ Index: 1, IsExternal: true }))).toBe(true);
+    expect(isExternalSubtitle(emb(2))).toBe(false);
+    // A DeliveryUrl alone (e.g. an Hls-delivered sub) is NOT a sub-added sidecar.
+    expect(isExternalSubtitle(sub({ Index: 3, DeliveryUrl: "/x.srt" }))).toBe(
+      false,
+    );
+  });
+});
+
+describe("resolveSubtitleTrack — disable / notFound", () => {
+  test("index -1 or undefined disables", () => {
+    expect(resolve([], -1, [])).toEqual({ kind: "disable" });
+    expect(resolve([], undefined, [])).toEqual({ kind: "disable" });
+  });
+
+  test("index not present returns notFound", () => {
+    expect(resolve([emb(0)], 99, [track({ id: 1 })])).toEqual({
+      kind: "notFound",
+    });
+  });
+});
+
+describe("resolveSubtitleTrack — hidden embedded (#954)", () => {
+  // Server hides embedded subs: MediaStreams lists only the 3 externals,
+  // but mpv still demuxes the 3 embedded from the file → externals get ids 4,5,6.
+  const streams = [
+    ext(0, { Language: "por" }),
+    ext(1, { Language: "eng" }),
+    ext(2, { Language: "eng", Title: "SDH" }),
+  ];
+  const player = [
+    track({ id: 1, external: false, language: "eng", title: "CC" }),
+    track({ id: 2, external: false, language: "spa" }),
+    track({ id: 3, external: false, language: "fre" }),
+    track({ id: 4, external: true, externalFilename: "http://srv/sub/0.srt" }),
+    track({ id: 5, external: true, externalFilename: "http://srv/sub/1.srt" }),
+    track({ id: 6, external: true, externalFilename: "http://srv/sub/2.srt" }),
+  ];
+
+  test("each external maps to the right player id by filename (not 1,2,3)", () => {
+    expect(resolve(streams, 0, player)).toEqual({ kind: "select", trackId: 4 });
+    expect(resolve(streams, 1, player)).toEqual({ kind: "select", trackId: 5 });
+    expect(resolve(streams, 2, player)).toEqual({ kind: "select", trackId: 6 });
+  });
+
+  test("falls back to external ordinal when filenames are unavailable", () => {
+    const noNames = player.map((t) =>
+      t.external ? { ...t, externalFilename: undefined } : t,
+    );
+    expect(resolve(streams, 1, noNames)).toEqual({
+      kind: "select",
+      trackId: 5,
+    });
+  });
+});
+
+describe("resolveSubtitleTrack — external/embed reversal (non-hidden)", () => {
+  // Jellyfin lists externals first; mpv lists embedded first then externals.
+  const streams = [
+    ext(0, { Language: "eng" }),
+    emb(1, { Language: "spa" }),
+    emb(2, { Language: "fre" }),
+  ];
+  const player = [
+    track({ id: 1, external: false, language: "spa" }),
+    track({ id: 2, external: false, language: "fre" }),
+    track({ id: 3, external: true, externalFilename: "http://srv/sub/0.srt" }),
+  ];
+
+  test("external resolves by filename, embedded by language", () => {
+    expect(resolve(streams, 0, player)).toEqual({ kind: "select", trackId: 3 });
+    expect(resolve(streams, 1, player)).toEqual({ kind: "select", trackId: 1 });
+    expect(resolve(streams, 2, player)).toEqual({ kind: "select", trackId: 2 });
+  });
+});
+
+describe("resolveSubtitleTrack — external without DeliveryUrl (#1763 CodeRabbit)", () => {
+  // Middle external has no DeliveryUrl → never loaded into the player.
+  const streams = [
+    ext(0, { Language: "eng", DeliveryUrl: "/sub/a.srt" }),
+    sub({ Index: 1, DeliveryMethod: External, IsExternal: true }),
+    ext(2, { Language: "fre", DeliveryUrl: "/sub/c.srt" }),
+  ];
+  const player = [
+    track({ id: 4, external: true, externalFilename: "http://srv/sub/a.srt" }),
+    track({ id: 5, external: true, externalFilename: "http://srv/sub/c.srt" }),
+  ];
+
+  test("loaded externals still map correctly despite the gap", () => {
+    expect(resolve(streams, 0, player)).toEqual({ kind: "select", trackId: 4 });
+    expect(resolve(streams, 2, player)).toEqual({ kind: "select", trackId: 5 });
+  });
+
+  test("selecting the unloaded external returns notFound", () => {
+    expect(resolve(streams, 1, player)).toEqual({ kind: "notFound" });
+  });
+});
+
+describe("resolveSubtitleTrack — embedded matching", () => {
+  test("unique language match wins even when player order differs (not positional)", () => {
+    const streams = [emb(0, { Language: "eng" }), emb(1, { Language: "jpn" })];
+    // Player lists them in the OPPOSITE order — a positional map would mis-pick.
+    const player = [
+      track({ id: 1, external: false, language: "jpn" }),
+      track({ id: 2, external: false, language: "eng" }),
+    ];
+    expect(resolve(streams, 0, player)).toEqual({ kind: "select", trackId: 2 }); // eng
+    expect(resolve(streams, 1, player)).toEqual({ kind: "select", trackId: 1 }); // jpn
+  });
+
+  test("same-language tracks with no distinguishing title fall back to ordinal among matches", () => {
+    const streams = [emb(0, { Language: "eng" }), emb(1, { Language: "eng" })];
+    // Both eng, no title → identity can't disambiguate → ordinal among matches.
+    const player = [
+      track({ id: 5, external: false, language: "eng" }),
+      track({ id: 6, external: false, language: "eng" }),
+    ];
+    expect(resolve(streams, 0, player)).toEqual({ kind: "select", trackId: 5 });
+    expect(resolve(streams, 1, player)).toEqual({ kind: "select", trackId: 6 });
+  });
+
+  test("falls back to embedded ordinal when no language/title info", () => {
+    const streams = [emb(0), emb(1)];
+    const player = [
+      track({ id: 1, external: false }),
+      track({ id: 2, external: false }),
+    ];
+    expect(resolve(streams, 1, player)).toEqual({ kind: "select", trackId: 2 });
+  });
+});
+
+describe("compareTracksForMenu — jellyfin-web order", () => {
+  test("externals sort after embedded despite lower Index", () => {
+    const sorted = [
+      ext(0, { Language: "eng" }),
+      emb(7, { Language: "fra" }),
+    ].sort(compareTracksForMenu);
+    expect(sorted.map((s) => s.Index)).toEqual([7, 0]);
+  });
+
+  test("forced then default float to the top within a group", () => {
+    const sorted = [
+      emb(2, { Language: "eng" }),
+      emb(1, { Language: "eng", IsDefault: true }),
+      emb(0, { Language: "eng", IsForced: true }),
+    ].sort(compareTracksForMenu);
+    expect(sorted.map((s) => s.Index)).toEqual([0, 1, 2]);
+  });
+
+  test("full Okiku order: embedded first, externals last by Index", () => {
+    const streams = [
+      ext(0, { Language: "eng" }),
+      ext(1, { Language: "eng" }),
+      ext(2, { Language: "fra" }),
+      ext(3, { Language: "fra" }),
+      emb(7, { Language: "fra", Title: "French" }),
+    ];
+    expect([...streams].sort(compareTracksForMenu).map((s) => s.Index)).toEqual(
+      [7, 0, 1, 2, 3],
+    );
+  });
+});

utils/jellyfin/subtitleUtils.ts

@@ -1,91 +1,287 @@
 /**
- * Subtitle utility functions for mapping between Jellyfin and MPV track indices.
+ * Subtitle utilities: resolve a Jellyfin subtitle stream to the right track in
+ * the *player's real track list* by identity — never by positional counting.
  *
- * Jellyfin uses server-side indices (e.g., 3, 4, 5 for subtitles in MediaStreams).
- * MPV uses its own track IDs starting from 1, only counting tracks loaded into MPV.
+ * Why: Jellyfin renumbers MediaStreams (externals first); the player enumerates
+ * embedded-from-container first and externals (`sub-add`) last; and a library that
+ * hides embedded subs drops them from MediaStreams while the player still demuxes
+ * them from the file. Positional Index→id mapping therefore mis-selects (e.g.
+ * picking Spanish shows English). See {@link resolveSubtitleTrack}.
  *
  * Image-based subtitles (PGS, VOBSUB) during transcoding are burned into the video
- * and NOT available in MPV's track list.
+ * and absent from the player's track list.
  */
 
-import {
-  type MediaSourceInfo,
-  type MediaStream,
+import type {
+  MediaSourceInfo,
+  MediaStream,
   SubtitleDeliveryMethod,
 } from "@jellyfin/sdk/lib/generated-client";
 
+// "External" is the value of SubtitleDeliveryMethod.External. Compared as a typed
+// literal so this util needs no *runtime* import of the SDK barrel — which pulls in
+// the axios-dependent `/api` modules and breaks unit tests under `bun test`.
+const EXTERNAL_DELIVERY = "External" as SubtitleDeliveryMethod;
+
 /** Check if subtitle is image-based (PGS, VOBSUB, etc.) */
 export const isImageBasedSubtitle = (sub: MediaStream): boolean =>
   sub.IsTextSubtitleStream === false;
 
 /**
- * Determine if a subtitle will be available in MPV's track list.
+ * A Jellyfin subtitle stream is "external" when the server delivers it as a
+ * sub-added sidecar — i.e. `DeliveryMethod === External` (or the `IsExternal`
+ * flag before a device-specific delivery method is assigned).
  *
- * A subtitle is in MPV if:
- * - Delivery is Embed/Hls/External AND not an image-based sub during transcode
+ * Deliberately NOT keyed on `DeliveryUrl`: an Hls-delivered sub also carries a
+ * `DeliveryUrl` but lives inside the player's track list (not `sub-add`-ed), so
+ * it must resolve through the embedded path. Keeping this in lockstep with the
+ * load sites (which only `sub-add` `DeliveryMethod === External`) and with the
+ * menu comparator below avoids a sub being sorted as embedded yet resolved as
+ * external (→ `notFound`).
  */
-export const isSubtitleInMpv = (
-  sub: MediaStream,
-  isTranscoding: boolean,
-): boolean => {
-  // During transcoding, image-based subs are burned in, not in MPV
-  if (isTranscoding && isImageBasedSubtitle(sub)) {
-    return false;
-  }
+export const isExternalSubtitle = (sub: MediaStream): boolean =>
+  sub.DeliveryMethod === EXTERNAL_DELIVERY || sub.IsExternal === true;
 
-  // Embed/Hls/External methods mean the sub is loaded into MPV
-  return (
-    sub.DeliveryMethod === SubtitleDeliveryMethod.Embed ||
-    sub.DeliveryMethod === SubtitleDeliveryMethod.Hls ||
-    sub.DeliveryMethod === SubtitleDeliveryMethod.External
-  );
+/**
+ * Order subtitle MediaStreams for the selection menu exactly like jellyfin-web's
+ * `itemHelper.sortTracks`: in-container tracks first then external, and within
+ * each group forced first, then default, then `Index` ascending. Callers prepend
+ * their own "None/Off" entry separately.
+ *
+ * The Jellyfin server inserts external (sidecar) streams at the FRONT of
+ * `MediaStreams` (low indices), so raw Index order shows externals first — this
+ * comparator flips that to match web (externals last). Uses {@link isExternalSubtitle}
+ * (not the raw `IsExternal` flag) so ordering and resolution agree.
+ */
+export const compareTracksForMenu = (a: MediaStream, b: MediaStream): number =>
+  Number(isExternalSubtitle(a)) - Number(isExternalSubtitle(b)) ||
+  Number(b.IsForced ?? false) - Number(a.IsForced ?? false) ||
+  Number(b.IsDefault ?? false) - Number(a.IsDefault ?? false) ||
+  (a.Index ?? 0) - (b.Index ?? 0);
+
+/**
+ * Identity of a subtitle track as reported by the *player's real track list*
+ * (mpv `track-list`, or a Cast media-track list). Player-agnostic on purpose so
+ * the same resolver can drive the mpv player today and the Chromecast backend later.
+ */
+export type PlayerSubtitleTrack = {
+  /** Player-side id used to actually select the track (mpv `sid`, cast trackId). */
+  id: number;
+  /** True if loaded from a separate file (mpv `external`). */
+  external?: boolean;
+  /** For external tracks: the exact URL/path it was loaded from (mpv `external-filename`). */
+  externalFilename?: string;
+  language?: string;
+  title?: string;
+  codec?: string;
+};
+
+export type SubtitleSelection =
+  | { kind: "select"; trackId: number }
+  | { kind: "disable" }
+  | { kind: "notFound" };
+
+/** Decode percent-encoding and strip a leading `file://` scheme for tolerant comparison. */
+const normalizeUrl = (url: string): string => {
+  let u = url;
+  try {
+    u = decodeURIComponent(u);
+  } catch {
+    // not decodable — compare raw
+  }
+  return u.replace(/^file:\/\//, "");
+};
+
+const externalFilenameMatches = (
+  trackFilename: string | undefined,
+  expectedUrl: string | undefined,
+): boolean => {
+  if (!trackFilename || !expectedUrl) return false;
+  const a = normalizeUrl(trackFilename);
+  const b = normalizeUrl(expectedUrl);
+  return a === b || a.endsWith(b) || b.endsWith(a);
+};
+
+const eq = (a?: string | null, b?: string | null): boolean =>
+  !!a && !!b && a.toLowerCase() === b.toLowerCase();
+
+/** Match an embedded player track to a Jellyfin stream by language/title (codec-agnostic). */
+const embeddedIdentityMatches = (
+  track: PlayerSubtitleTrack,
+  stream: MediaStream,
+): boolean => {
+  if (eq(track.language, stream.Language)) {
+    // When both carry a title it must agree; otherwise language alone is enough.
+    if (track.title && stream.Title) return eq(track.title, stream.Title);
+    return true;
+  }
+  // No language on one side — fall back to a title match.
+  if (!track.language || !stream.Language) return eq(track.title, stream.Title);
+  return false;
 };
 
 /**
- * Calculate the MPV track ID for a given Jellyfin subtitle index.
+ * Resolve the player track id for a given Jellyfin subtitle index by matching
+ * against the player's REAL track list (identity), never by positional counting.
  *
- * MPV track IDs are 1-based and only count subtitles that are actually in MPV.
- * We iterate through all subtitles, counting only those in MPV, until we find
- * the one matching the Jellyfin index.
+ * Why identity, not position: Jellyfin renumbers `MediaStreams` (externals first)
+ * while the player enumerates embedded-from-container first and externals
+ * (`sub-add`) last; and when a library hides embedded subs they vanish from
+ * `MediaStreams` but still physically exist in the file the player demuxes.
+ * Positional Index→id mapping therefore mis-selects (e.g. picking Spanish shows
+ * English — issues #954/#1690/#618/#1467/#976/#1451).
  *
- * @param mediaSource - The media source containing subtitle streams
- * @param jellyfinSubtitleIndex - The Jellyfin server-side subtitle index (-1 = disabled)
- * @param isTranscoding - Whether the stream is being transcoded
- * @returns MPV track ID (1-based), or -1 if disabled, or undefined if not in MPV
+ * Strategy:
+ *  - disabled (-1/undefined) → `disable`
+ *  - external Jellyfin sub → match the player track by `externalFilename`
+ *    (exact identity, immune to hidden-embedded shifts); fall back to the
+ *    ordinal among *loadable* externals (Swiftfin: externals are the list tail).
+ *  - embedded Jellyfin sub → match by language/title among non-external tracks;
+ *    fall back to the embedded ordinal (container order aligns on both sides).
+ *
+ * Player-agnostic: pass any player's track list + a URL builder, so the mpv
+ * player and (later) the Chromecast backend share one source of truth.
  */
-export const getMpvSubtitleId = (
-  mediaSource: MediaSourceInfo | null | undefined,
-  jellyfinSubtitleIndex: number | undefined,
-  isTranscoding: boolean,
-): number | undefined => {
-  // -1 or undefined means disabled
+export const resolveSubtitleTrack = (params: {
+  subtitleStreams: MediaStream[] | undefined;
+  jellyfinSubtitleIndex: number | undefined;
+  playerTracks: PlayerSubtitleTrack[];
+  /** Build the exact URL/path an external Jellyfin sub was loaded into the player with. */
+  getExpectedExternalUrl?: (sub: MediaStream) => string | undefined;
+}): SubtitleSelection => {
+  const { jellyfinSubtitleIndex, playerTracks, getExpectedExternalUrl } =
+    params;
+  const subtitleStreams = params.subtitleStreams ?? [];
+
   if (jellyfinSubtitleIndex === undefined || jellyfinSubtitleIndex === -1) {
-    return -1;
+    return { kind: "disable" };
   }
 
-  const allSubs =
-    mediaSource?.MediaStreams?.filter((s) => s.Type === "Subtitle") || [];
+  const target = subtitleStreams.find((s) => s.Index === jellyfinSubtitleIndex);
+  if (!target) return { kind: "notFound" };
 
-  // Find the subtitle with the matching Jellyfin index
-  const targetSub = allSubs.find((s) => s.Index === jellyfinSubtitleIndex);
+  if (isExternalSubtitle(target)) {
+    const playerExternals = playerTracks.filter((t) => t.external === true);
 
-  // If the target subtitle isn't in MPV (e.g., image-based during transcode), return undefined
-  if (!targetSub || !isSubtitleInMpv(targetSub, isTranscoding)) {
-    return undefined;
-  }
+    // 1) Exact identity by external filename — robust against hidden-embedded offset.
+    const expectedUrl = getExpectedExternalUrl?.(target);
+    const byName = playerExternals.find((t) =>
+      externalFilenameMatches(t.externalFilename, expectedUrl),
+    );
+    if (byName) return { kind: "select", trackId: byName.id };
 
-  // Count MPV track position (1-based)
-  let mpvIndex = 0;
-  for (const sub of allSubs) {
-    if (isSubtitleInMpv(sub, isTranscoding)) {
-      mpvIndex++;
-      if (sub.Index === jellyfinSubtitleIndex) {
-        return mpvIndex;
-      }
+    // 2) Fallback: externals are appended in MediaStreams order → ordinal among
+    //    *loadable* externals (those actually added to the player) stays in lockstep
+    //    with the player's external list, skipping ones with no DeliveryUrl (#1763).
+    const externalStreams = subtitleStreams.filter(isExternalSubtitle);
+    const loadableExternals = getExpectedExternalUrl
+      ? externalStreams.filter((s) => getExpectedExternalUrl(s))
+      : externalStreams;
+    const ordinal = loadableExternals.findIndex(
+      (s) => s.Index === jellyfinSubtitleIndex,
+    );
+    if (ordinal >= 0 && ordinal < playerExternals.length) {
+      return { kind: "select", trackId: playerExternals[ordinal].id };
     }
+    return { kind: "notFound" };
   }
 
-  return undefined;
+  // Embedded / in-container subtitle.
+  const embeddedStreams = subtitleStreams.filter((s) => !isExternalSubtitle(s));
+  const playerEmbedded = playerTracks.filter((t) => t.external !== true);
+
+  // 1) Identity by language/title (unique match wins).
+  const identityMatches = playerEmbedded.filter((t) =>
+    embeddedIdentityMatches(t, target),
+  );
+  if (identityMatches.length === 1) {
+    return { kind: "select", trackId: identityMatches[0].id };
+  }
+
+  // 2) Fallback: embedded order is container order on both sides → ordinal.
+  const ordinal = embeddedStreams.findIndex(
+    (s) => s.Index === jellyfinSubtitleIndex,
+  );
+  if (identityMatches.length > 1 && ordinal >= 0) {
+    // Multiple same-language tracks: pick by position among the matches.
+    const idx = Math.min(ordinal, identityMatches.length - 1);
+    return { kind: "select", trackId: identityMatches[idx].id };
+  }
+  if (ordinal >= 0 && ordinal < playerEmbedded.length) {
+    return { kind: "select", trackId: playerEmbedded[ordinal].id };
+  }
+  return { kind: "notFound" };
+};
+
+/**
+ * A subtitle track as reported by a concrete player's track-list API
+ * (mpv `getSubtitleTracks`, or a Cast track list). `lang` mirrors mpv's field name.
+ */
+export type PlayerSubtitleTrackRaw = {
+  id: number;
+  lang?: string;
+  title?: string;
+  codec?: string;
+  external?: boolean;
+  externalFilename?: string;
+};
+
+/**
+ * Minimal player surface needed to select a subtitle. Satisfied structurally by
+ * the mpv player ref and (later) implementable by the Chromecast backend.
+ */
+export interface SubtitleSelectablePlayer {
+  getSubtitleTracks: () => Promise<PlayerSubtitleTrackRaw[] | null | undefined>;
+  setSubtitleTrack: (trackId: number) => unknown;
+  disableSubtitles: () => unknown;
+}
+
+/**
+ * Read the player's real track list, resolve the Jellyfin subtitle index by
+ * identity ({@link resolveSubtitleTrack}) and apply the result. Single entry point
+ * for both the mobile controls and the player screen, so selection stays
+ * consistent everywhere. Returns the resolution for callers that want to react.
+ */
+export const applyMpvSubtitleSelection = async (
+  player: SubtitleSelectablePlayer | null | undefined,
+  params: {
+    subtitleStreams: MediaStream[] | undefined;
+    jellyfinSubtitleIndex: number;
+    /** Build the exact URL/path an external sub was loaded into the player with. */
+    getExpectedExternalUrl?: (sub: MediaStream) => string | undefined;
+  },
+): Promise<SubtitleSelection> => {
+  if (!player) return { kind: "notFound" };
+
+  // Called fire-and-forget (`void applyMpvSubtitleSelection(...)`), so any native
+  // rejection from getSubtitleTracks/setSubtitleTrack/disableSubtitles must be
+  // swallowed here instead of escaping as an unhandled promise rejection.
+  try {
+    const tracks = (await player.getSubtitleTracks()) ?? [];
+    const selection = resolveSubtitleTrack({
+      subtitleStreams: params.subtitleStreams,
+      jellyfinSubtitleIndex: params.jellyfinSubtitleIndex,
+      playerTracks: tracks.map((t) => ({
+        id: t.id,
+        external: t.external,
+        externalFilename: t.externalFilename,
+        language: t.lang,
+        title: t.title,
+        codec: t.codec,
+      })),
+      getExpectedExternalUrl: params.getExpectedExternalUrl,
+    });
+
+    if (selection.kind === "select") {
+      await player.setSubtitleTrack(selection.trackId);
+    } else if (selection.kind === "disable") {
+      await player.disableSubtitles();
+    }
+    // notFound → leave current selection (e.g. image subs burned in while transcoding)
+    return selection;
+  } catch {
+    return { kind: "notFound" };
+  }
 };
 
 /**