diff --git a/utils/casting/castErrors.test.ts b/utils/casting/castErrors.test.ts
new file mode 100644
index 000000000..abec6f6bd
--- /dev/null
+++ b/utils/casting/castErrors.test.ts
@@ -0,0 +1,20 @@
+import { describe, expect, test } from "bun:test";
+import { isLoadFailedError } from "./castErrors";
+
+describe("isLoadFailedError", () => {
+  test("recognises a status 2100 error message", () => {
+    const error = new Error(
+      "java.lang.Exception: Media control channel status code 2100",
+    );
+    expect(isLoadFailedError(error)).toBe(true);
+  });
+
+  test("returns false for unrelated errors", () => {
+    expect(isLoadFailedError(new Error("network timeout"))).toBe(false);
+  });
+
+  test("handles non-Error values without throwing", () => {
+    expect(isLoadFailedError("status code 2100")).toBe(true);
+    expect(isLoadFailedError(null)).toBe(false);
+  });
+});
diff --git a/utils/casting/castErrors.ts b/utils/casting/castErrors.ts
new file mode 100644
index 000000000..bd76c81c7
--- /dev/null
+++ b/utils/casting/castErrors.ts
@@ -0,0 +1,11 @@
+/**
+ * Cast load error classification. Kept dependency-free so it is unit-testable
+ * without pulling React Native modules into the test runtime.
+ */
+
+/** True when an error is a Cast "LOAD_FAILED" (status 2100) rejection. */
+export const isLoadFailedError = (error: unknown): boolean => {
+  if (error == null) return false;
+  const message = error instanceof Error ? error.message : String(error);
+  return message.includes("2100");
+};
diff --git a/utils/casting/castLoad.ts b/utils/casting/castLoad.ts
new file mode 100644
index 000000000..1ab612356
--- /dev/null
+++ b/utils/casting/castLoad.ts
@@ -0,0 +1,137 @@
+/**
+ * Unified Chromecast media loading.
+ *
+ * Owns the getStreamUrl → buildCastMediaInfo → loadMedia sequence that was
+ * previously duplicated across PlayButton and the casting player. Builds the
+ * device profile from detected capabilities and retries once with a forced
+ * conservative profile when the receiver rejects the initial load (status 2100).
+ */
+
+import type { Api } from "@jellyfin/sdk";
+import type { BaseItemDto } from "@jellyfin/sdk/lib/generated-client";
+import type { RemoteMediaClient } from "react-native-google-cast";
+import { buildChromecastProfile } from "@/utils/casting/buildProfile";
+import {
+  type ChromecastProfileMode,
+  detectCapabilities,
+} from "@/utils/casting/capabilities";
+import { isLoadFailedError } from "@/utils/casting/castErrors";
+import { buildCastMediaInfo } from "@/utils/casting/mediaInfo";
+import { getStreamUrl } from "@/utils/jellyfin/media/getStreamUrl";
+
+export interface CastLoadOptions {
+  audioStreamIndex?: number;
+  subtitleStreamIndex?: number;
+  maxBitrate?: number;
+  mediaSourceId?: string;
+  startPositionMs?: number;
+}
+
+export interface CastLoadParams {
+  client: RemoteMediaClient;
+  /** Cast device — only `modelName` is read, for capability detection. */
+  device: { modelName?: string } | null;
+  api: Api;
+  item: BaseItemDto;
+  userId: string;
+  profileMode: ChromecastProfileMode;
+  /** Manual bitrate cap from settings, in bits per second. */
+  maxBitrateSetting?: number;
+  options?: CastLoadOptions;
+}
+
+export type CastLoadResult = { ok: true } | { ok: false; error: unknown };
+
+/**
+ * Resolve the default audio stream index for an item.
+ * Fixes the previous `audioStreamIndex = 0` default, which selected the video stream.
+ */
+export const resolveDefaultAudioIndex = (
+  item: BaseItemDto,
+  mediaSourceId?: string,
+): number | undefined => {
+  const source = mediaSourceId
+    ? item.MediaSources?.find((s) => s.Id === mediaSourceId)
+    : item.MediaSources?.[0];
+  if (source?.DefaultAudioStreamIndex != null) {
+    return source.DefaultAudioStreamIndex;
+  }
+  const audio =
+    item.MediaStreams?.find((s) => s.Type === "Audio" && s.IsDefault) ??
+    item.MediaStreams?.find((s) => s.Type === "Audio");
+  return audio?.Index ?? undefined;
+};
+
+const attemptLoad = async (
+  params: CastLoadParams,
+  caps: Parameters<typeof buildChromecastProfile>[0],
+): Promise<void> => {
+  const { api, item, userId, client, options } = params;
+  const profile = buildChromecastProfile(caps);
+  const audioStreamIndex =
+    options?.audioStreamIndex ??
+    resolveDefaultAudioIndex(item, options?.mediaSourceId);
+  const startPositionMs = options?.startPositionMs ?? 0;
+
+  const data = await getStreamUrl({
+    api,
+    item,
+    userId,
+    startTimeTicks: Math.floor(startPositionMs * 10000),
+    deviceProfile: profile,
+    audioStreamIndex,
+    subtitleStreamIndex: options?.subtitleStreamIndex,
+    maxStreamingBitrate: options?.maxBitrate,
+    mediaSourceId: options?.mediaSourceId,
+  });
+
+  if (!data?.url) {
+    throw new Error("getStreamUrl returned no URL");
+  }
+
+  await client.loadMedia({
+    mediaInfo: buildCastMediaInfo({
+      item,
+      streamUrl: data.url,
+      api,
+      playSessionId: data.sessionId ?? undefined,
+    }),
+    startTime: startPositionMs / 1000,
+  });
+};
+
+/**
+ * Load media onto the connected Chromecast.
+ * On a status-2100 rejection, retries once with a forced conservative profile.
+ */
+export const loadCastMedia = async (
+  params: CastLoadParams,
+): Promise<CastLoadResult> => {
+  const caps = detectCapabilities(params.device, {
+    profileMode: params.profileMode,
+    maxBitrate: params.maxBitrateSetting,
+  });
+
+  try {
+    await attemptLoad(params, caps);
+    return { ok: true };
+  } catch (error) {
+    if (!isLoadFailedError(error)) {
+      return { ok: false, error };
+    }
+    // Downgrade-on-failure: one retry with the safest possible profile.
+    try {
+      const fallback = detectCapabilities(params.device, {
+        profileMode: "force-h264",
+      });
+      await attemptLoad(params, {
+        ...fallback,
+        maxVideoBitrate: 4_000_000,
+        maxAudioChannels: 2,
+      });
+      return { ok: true };
+    } catch (retryError) {
+      return { ok: false, error: retryError };
+    }
+  }
+};
diff --git a/utils/casting/mediaInfo.ts b/utils/casting/mediaInfo.ts
index fcc83b9e8..7a88eaecd 100644
--- a/utils/casting/mediaInfo.ts
+++ b/utils/casting/mediaInfo.ts
@@ -23,6 +23,7 @@ export const buildCastMediaInfo = ({
   api,
   contentType,
   isLive = false,
+  playSessionId,
 }: {
   item: BaseItemDto;
   streamUrl: string;
@@ -31,6 +32,8 @@ export const buildCastMediaInfo = ({
   contentType?: string;
   /** Set true for live TV streams to use MediaStreamType.LIVE. */
   isLive?: boolean;
+  /** Jellyfin PlaySessionId, embedded in customData for progress reporting. */
+  playSessionId?: string;
 }) => {
   if (!item.Id) {
     throw new Error("Missing item.Id for media load — cannot build contentId");
@@ -84,7 +87,8 @@ export const buildCastMediaInfo = ({
   // Build a slim customData payload with only the fields the casting-player needs.
   // Sending the full BaseItemDto can exceed the Cast protocol's ~64KB message limit,
   // especially for movies with many chapters, media sources, and people.
-  const slimCustomData: Partial<BaseItemDto> = {
+  const slimCustomData: Partial<BaseItemDto> & { playSessionId?: string } = {
+    playSessionId,
     Id: item.Id,
     Name: item.Name,
     Type: item.Type,