diff --git a/utils/jellyfin/subtitleUtils.test.ts b/utils/jellyfin/subtitleUtils.test.ts
new file mode 100644
index 00000000..dab53326
--- /dev/null
+++ b/utils/jellyfin/subtitleUtils.test.ts
@@ -0,0 +1,218 @@
+import { describe, expect, test } from "bun:test";
+import type {
+  MediaStream,
+  SubtitleDeliveryMethod,
+} from "@jellyfin/sdk/lib/generated-client";
+import {
+  compareTracksForMenu,
+  isExternalSubtitle,
+  type PlayerSubtitleTrack,
+  resolveSubtitleTrack,
+} from "./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, IsExternal flag, or a DeliveryUrl", () => {
+    expect(isExternalSubtitle(ext(0))).toBe(true);
+    expect(isExternalSubtitle(sub({ Index: 1, DeliveryUrl: "/x.srt" }))).toBe(
+      true,
+    );
+    expect(isExternalSubtitle(emb(2))).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 regardless of order", () => {
+    const streams = [emb(0, { Language: "eng" }), emb(1, { Language: "jpn" })];
+    const player = [
+      track({ id: 1, external: false, language: "eng" }),
+      track({ id: 2, external: false, language: "jpn" }),
+    ];
+    expect(resolve(streams, 1, player)).toEqual({ kind: "select", trackId: 2 });
+  });
+
+  test("same-language tracks disambiguate by ordinal among matches", () => {
+    const streams = [
+      emb(0, { Language: "eng", Title: "Full" }),
+      emb(1, { Language: "eng", Title: "SDH" }),
+    ];
+    const player = [
+      track({ id: 1, external: false, language: "eng", title: "Full" }),
+      track({ id: 2, external: false, language: "eng", title: "SDH" }),
+    ];
+    expect(resolve(streams, 1, player)).toEqual({ kind: "select", trackId: 2 });
+  });
+
+  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],
+    );
+  });
+});
diff --git a/utils/jellyfin/subtitleUtils.ts b/utils/jellyfin/subtitleUtils.ts
index f20f8521..7cb23e84 100644
--- a/utils/jellyfin/subtitleUtils.ts
+++ b/utils/jellyfin/subtitleUtils.ts
@@ -1,91 +1,270 @@
 /**
- * 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 subtitle is in MPV if:
- * - Delivery is Embed/Hls/External AND not an image-based sub during transcode
- */
-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;
-  }
+/** A Jellyfin subtitle stream is "external" when the server delivers it as a sidecar file. */
+export const isExternalSubtitle = (sub: MediaStream): boolean =>
+  sub.DeliveryMethod === EXTERNAL_DELIVERY ||
+  sub.IsExternal === true ||
+  Boolean(sub.DeliveryUrl);
 
-  // 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/audio 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).
+ */
+export const compareTracksForMenu = (a: MediaStream, b: MediaStream): number =>
+  Number(a.IsExternal ?? false) - Number(b.IsExternal ?? false) ||
+  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" };
+
+  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;
 };
 
 /**