feat(players): keep a video playing in the background on Brave iOS; repeat on the watch page

On iPad Brave, a shared video stopped the moment the browser left the
foreground, even with Brave's "Enable Background Audio" on, while an mp3
kept playing. Brave iOS keeps a web <video> going by re-playing one the OS
paused (brave-core ios/browser/web/media/resources/media_backgrounding.ts),
but it only hooks a <video> present at document start or added as a
MutationObserver addedNode that IS a video. React inserts a player's
<video> inside its freshly mounted wrapper in one go, so Brave never saw it.

lib/browserBackgroundPlay re-inserts a mounted <video> at its own position,
once per element: it becomes an added node, the DOM React manages does not
change, and playback is not interrupted. The watch page, the downloads
library player and the Plex player hand their <video> to it. Measured on the
owner's iPad (Brave) with a prototype of the same idea: the video kept
playing in another app and with the screen locked. The YouTube modal is not
ours to change: its <video> lives in YouTube's cross-origin iframe, and
nothing of ours pauses it on backgrounding.

The prototype's two audio-element variants (a muted video following an
<audio>, and an <audio> taking over on hide) went silent in the background on
the iPad and are removed.

The watch page gets a Repeat toggle, on by default and remembered per
browser (LS.watchRepeat; the page has no account): it sets `loop` on the
<video> or the audio-only <audio>.

frontend/src/components/LibraryPlayer.dom.test.tsx

@@ -11,6 +11,8 @@ vi.mock("react-i18next", async (importOriginal) => {
   const actual = await importOriginal<typeof import("react-i18next")>();
   return { ...actual, useTranslation: () => ({ t: (key: string) => key }) };
 });
+const expose = vi.hoisted(() => vi.fn());
+vi.mock("../lib/browserBackgroundPlay", () => ({ exposeVideoToBackgroundPlay: expose }));
 
 import LibraryPlayer from "./LibraryPlayer";
 import type { DownloadJob } from "../lib/api";
@@ -90,6 +92,11 @@ describe("LibraryPlayer", () => {
     expect(document.body.querySelector("audio")).toBeNull();
   });
 
+  it("hands its <video> to the background-play hook, so Brave iOS keeps it playing", () => {
+    render(<LibraryPlayer job={withAsset({ width: 1280, height: 720 })} onClose={() => {}} />);
+    expect(expose).toHaveBeenCalledWith(document.body.querySelector("video"));
+  });
+
   it("plays an audio-only asset (media_kind='audio') in an <audio> element", () => {
     render(
       <LibraryPlayer

frontend/src/components/LibraryPlayer.tsx

@@ -3,6 +3,7 @@ import { useTranslation } from "react-i18next";
 import Modal from "./ui/Modal";
 import { api, type DownloadJob } from "../lib/api";
 import { jobTitle } from "./downloadRow";
+import { exposeVideoToBackgroundPlay } from "../lib/browserBackgroundPlay";
 
 // E7 S4b — in-app player for a completed library item. We do NOT reuse PlayerModal (a cross-origin
 // YouTube IFrame shell) or PlexPlayer (a Plex HLS/session shell): both are bound to their own domain
@@ -47,6 +48,7 @@ export default function LibraryPlayer({ job, onClose }: { job: DownloadJob; onCl
         </div>
       ) : (
         <video
+          ref={exposeVideoToBackgroundPlay}
           src={fileUrl}
           poster={poster}
           controls

frontend/src/components/PlexPlayer.strictmode.dom.test.tsx

@@ -21,6 +21,9 @@ vi.mock("react-i18next", async (importOriginal) => {
   };
 });
 
+const expose = vi.hoisted(() => vi.fn());
+vi.mock("../lib/browserBackgroundPlay", () => ({ exposeVideoToBackgroundPlay: expose }));
+
 import PlexPlayer from "./PlexPlayer";
 import { api, type PlexItemDetail } from "../lib/api";
 
@@ -98,4 +101,21 @@ describe("PlexPlayer under StrictMode", () => {
     video.dispatchEvent(new Event("loadedmetadata"));
     await waitFor(() => expect(played).toContain("/api/plex/direct/99079"));
   });
+
+  it("hands its <video> to the background-play hook, so Brave iOS keeps it playing", async () => {
+    vi.spyOn(api, "plexItem").mockResolvedValue(detail);
+    vi.spyOn(api, "plexSession").mockResolvedValue({
+      mode: "direct",
+      url: "/api/plex/direct/99079",
+      start_s: 0,
+    } as never);
+    const qc = new QueryClient({ defaultOptions: { queries: { retry: false } } });
+    render(
+      <QueryClientProvider client={qc}>
+        <PlexPlayer itemId="99079" onClose={() => {}} />
+      </QueryClientProvider>,
+    );
+    const video = await waitFor(() => document.querySelector("video")!);
+    expect(expose).toHaveBeenCalledWith(video);
+  });
 });

frontend/src/components/PlexPlayer.tsx

@@ -3,6 +3,7 @@ import { qk } from "../lib/queryKeys";
 import { createPortal } from "react-dom";
 import { useTranslation } from "react-i18next";
 import { plexLang } from "../i18n";
+import { exposeVideoToBackgroundPlay } from "../lib/browserBackgroundPlay";
 import { useQuery, useQueryClient } from "@tanstack/react-query";
 import Hls from "hls.js";
 import {
@@ -115,7 +116,7 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
   const detail = detailQ.data;
   const duration = detail?.duration_seconds ?? 0;
 
-  const videoRef = useRef<HTMLVideoElement>(null);
+  const videoRef = useRef<HTMLVideoElement | null>(null);
   const hlsRef = useRef<Hls | null>(null);
   // False once unmounted, so a late play() (from MANIFEST_PARSED / loadedmetadata firing after Back)
   // can't start a detached <video> playing audio in the background.
@@ -1048,7 +1049,11 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
         prefs.subShadowColor,
       )}}`}</style>
       <video
-        ref={videoRef}
+        ref={(el) => {
+          videoRef.current = el;
+          // So Brave iOS's background play keeps it going when the app is left (lib/browserBackgroundPlay).
+          exposeVideoToBackgroundPlay(el);
+        }}
         // Fill the wrapper (which is sized to the viewport / screen) and letterbox by aspect via
         // object-contain. NOT `w-auto h-auto max-*`: that caps the video at its intrinsic resolution
         // (a 720p stream → 1280×720) and never scales it UP, so in fullscreen it sat tiny and centred.

frontend/src/components/WatchPage.dom.test.tsx

@@ -5,7 +5,10 @@
 // mp3 inside a <video>, which is exactly why the branch exists — this locks it so a refactor can't
 // silently drop the audio player and reintroduce the iPad-broken behavior.
 import { afterEach, describe, expect, it, vi } from "vitest";
-import { render, waitFor, cleanup } from "@testing-library/react";
+import { render, waitFor, cleanup, fireEvent } from "@testing-library/react";
+const expose = vi.hoisted(() => vi.fn());
+vi.mock("../lib/browserBackgroundPlay", () => ({ exposeVideoToBackgroundPlay: expose }));
+
 import WatchPage from "./WatchPage";
 
 function mockMeta(meta: Record<string, unknown>) {
@@ -18,6 +21,50 @@ function mockMeta(meta: Record<string, unknown>) {
 afterEach(() => {
   cleanup();
   vi.unstubAllGlobals();
+  localStorage.clear();
+});
+
+describe("WatchPage background play", () => {
+  it("hands its <video> to the background-play hook, so Brave iOS keeps it playing", async () => {
+    window.history.replaceState({}, "", "/watch/tok-bg");
+    mockMeta({ needs_password: false, audio: false, file_url: "/f.mp4", title: "A clip" });
+    const { container } = render(<WatchPage />);
+    await waitFor(() => expect(container.querySelector("video")).not.toBeNull());
+    expect(expose).toHaveBeenCalledWith(container.querySelector("video"));
+  });
+});
+
+describe("WatchPage repeat", () => {
+  it("repeats by default, for a video and for an audio-only asset", async () => {
+    window.history.replaceState({}, "", "/watch/tok-repeat-video");
+    mockMeta({ needs_password: false, audio: false, file_url: "/f.mp4", title: "A clip" });
+    const video = render(<WatchPage />);
+    await waitFor(() => expect(video.container.querySelector("video")).not.toBeNull());
+    expect(video.container.querySelector("video")!.loop).toBe(true);
+    cleanup();
+
+    window.history.replaceState({}, "", "/watch/tok-repeat-audio");
+    mockMeta({ needs_password: false, audio: true, file_url: "/f.mp3", title: "A song" });
+    const audio = render(<WatchPage />);
+    await waitFor(() => expect(audio.container.querySelector("audio")).not.toBeNull());
+    expect(audio.container.querySelector("audio")!.loop).toBe(true);
+  });
+
+  it("the toggle turns it off, and the choice is remembered for the next visit", async () => {
+    window.history.replaceState({}, "", "/watch/tok-repeat-toggle");
+    mockMeta({ needs_password: false, audio: false, file_url: "/f.mp4", title: "A clip" });
+    const first = render(<WatchPage />);
+    const toggle = await first.findByRole("button", { name: "Repeat" });
+    expect(toggle.getAttribute("aria-pressed")).toBe("true");
+    fireEvent.click(toggle);
+    expect(toggle.getAttribute("aria-pressed")).toBe("false");
+    expect(first.container.querySelector("video")!.loop).toBe(false);
+    cleanup();
+
+    const second = render(<WatchPage />);
+    await waitFor(() => expect(second.container.querySelector("video")).not.toBeNull());
+    expect(second.container.querySelector("video")!.loop).toBe(false);
+  });
 });
 
 describe("WatchPage media element (S3 · 5a)", () => {

frontend/src/components/WatchPage.tsx

@@ -1,13 +1,9 @@
 import { useEffect, useRef, useState } from "react";
-import { Download, File as FileIcon, Link2, Lock, PlayCircle } from "lucide-react";
+import { Download, File as FileIcon, Link2, Lock, PlayCircle, Repeat } from "lucide-react";
 import { Button } from "./ui/Button";
 import { formatBytes } from "../lib/format";
-import {
-  followAudio,
-  handOverOnHide,
-  readBackgroundMode,
-  startPlayback,
-} from "../lib/watchBackgroundAudio";
+import { exposeVideoToBackgroundPlay } from "../lib/browserBackgroundPlay";
+import { LS } from "../lib/storage";
 
 // Standalone, login-free video page for a shared /watch/<token> link. Rendered OUTSIDE the app
 // tree (no auth, no providers) — like the /privacy and /terms pages. Uses plain fetch and a tiny
@@ -86,6 +82,7 @@ const STR = {
     file: "File",
     links: "Links",
     brand: "Shared via Siftlode",
+    repeat: "Repeat",
   },
   hu: {
     loading: "Betöltés…",
@@ -99,6 +96,7 @@ const STR = {
     file: "Fájl",
     links: "Linkek",
     brand: "Megosztva a Siftlode-dal",
+    repeat: "Ismétlés",
   },
   de: {
     loading: "Wird geladen…",
@@ -112,6 +110,7 @@ const STR = {
     file: "Datei",
     links: "Links",
     brand: "Geteilt über Siftlode",
+    repeat: "Wiederholen",
   },
 } as const;
 
@@ -136,23 +135,24 @@ export default function WatchPage() {
   };
   useMediaSession(mediaRef, meta, status === "ready");
 
-  // PROTOTYPE (dev only): background sound for a video on iPad, `?bg=a`, `?bg=b` or `?bg=c` — see
-  // lib/watchBackgroundAudio. Without the param the page behaves exactly as before.
-  const [bgMode] = useState(() => readBackgroundMode(window.location.search));
-  const audioMode = bgMode === "a" || bgMode === "b" ? bgMode : null;
-  const [videoEl, setVideoEl] = useState<HTMLVideoElement | null>(null);
-  const [audioEl, setAudioEl] = useState<HTMLAudioElement | null>(null);
-  const [started, setStarted] = useState(false);
-  useEffect(() => {
-    if (!audioMode || !videoEl || !audioEl) return;
-    return audioMode === "a" ? followAudio(videoEl, audioEl) : handOverOnHide(videoEl, audioEl);
-  }, [audioMode, videoEl, audioEl]);
-  // Mode "c": mount the player's wrapper first and the <video> in the NEXT commit, so the video enters
-  // the DOM as a node of its own — the only way Brave's background play notices it.
-  const [videoSlot, setVideoSlot] = useState(bgMode !== "c");
-  useEffect(() => {
-    if (status === "ready" && !videoSlot) setVideoSlot(true);
-  }, [status, videoSlot]);
+  // Repeat the shared media when it ends — on unless the viewer turned it off. Remembered per browser
+  // (this page has no account); an unreadable storage just means the default.
+  const [repeat, setRepeat] = useState(() => {
+    try {
+      return localStorage.getItem(LS.watchRepeat) !== "0";
+    } catch {
+      return true;
+    }
+  });
+  const toggleRepeat = () => {
+    const next = !repeat;
+    setRepeat(next);
+    try {
+      localStorage.setItem(LS.watchRepeat, next ? "1" : "0");
+    } catch {
+      /* storage unavailable — the toggle still applies to this visit */
+    }
+  };
 
   useEffect(() => {
     if (!token) {
@@ -283,54 +283,31 @@ export default function WatchPage() {
                  <audio>. No poster exists for these, so present it as a deliberate padded bar on
                  the surface (not the black video box) so it looks intentional without artwork. */
               <div className="rounded-xl border border-border bg-surface p-4">
-                <audio ref={setMedia} controls src={meta.file_url} className="w-full block" />
+                <audio
+                  ref={setMedia}
+                  controls
+                  loop={repeat}
+                  src={meta.file_url}
+                  className="w-full block"
+                />
               </div>
             ) : (
               /* Shrink-wrap the player to the video so a vertical/short clip renders as a narrow
                  player instead of a wide box with black bars; a landscape clip fills the width. */
-              <div className="relative rounded-xl overflow-hidden bg-black border border-border w-fit max-w-full mx-auto">
-                {videoSlot && (
-                  <video
-                    ref={(el) => {
-                      setVideoEl(el);
-                      // Mode "a": the audio is the clock, so the lock-screen controls drive it instead.
-                      if (bgMode !== "a") setMedia(el);
-                    }}
-                    controls={!audioMode || started}
-                    playsInline
-                    muted={bgMode === "a"}
-                    src={meta.file_url}
-                    poster={meta.poster_url || undefined}
-                    className="max-h-[80vh] max-w-full mx-auto block"
-                  />
-                )}
-                {audioMode && (
-                  <audio
-                    ref={(el) => {
-                      setAudioEl(el);
-                      if (bgMode === "a") setMedia(el);
-                    }}
-                    src={meta.file_url}
-                    preload="auto"
-                    className="hidden"
-                  />
-                )}
-                {audioMode && !started && videoEl && audioEl && (
-                  <button
-                    type="button"
-                    data-testid="bg-start"
-                    onClick={() => {
-                      startPlayback(audioMode, videoEl, audioEl);
-                      setStarted(true);
-                    }}
-                    className="absolute inset-0 grid place-items-center bg-black/30"
-                  >
-                    <PlayCircle className="w-20 h-20 text-white drop-shadow" />
-                    <span className="absolute top-2 left-2 rounded bg-black/60 px-2 py-0.5 text-xs text-white">
-                      bg: {audioMode.toUpperCase()}
-                    </span>
-                  </button>
-                )}
+              <div className="rounded-xl overflow-hidden bg-black border border-border w-fit max-w-full mx-auto">
+                <video
+                  ref={(el) => {
+                    setMedia(el);
+                    // So Brave iOS's background play keeps it going when the app is left.
+                    exposeVideoToBackgroundPlay(el);
+                  }}
+                  controls
+                  playsInline
+                  loop={repeat}
+                  src={meta.file_url}
+                  poster={meta.poster_url || undefined}
+                  className="max-h-[80vh] max-w-full mx-auto block"
+                />
               </div>
             )}
             <div className="mt-3 flex items-start gap-3">
@@ -350,6 +327,16 @@ export default function WatchPage() {
                     <div className="text-sm text-muted">{meta.uploader}</div>
                   ))}
               </div>
+              <Button
+                variant={repeat ? "outline-accent" : "outline"}
+                size="md"
+                icon={<Repeat className="w-4 h-4" />}
+                aria-pressed={repeat}
+                onClick={toggleRepeat}
+                className="shrink-0"
+              >
+                {T.repeat}
+              </Button>
               {meta.allow_download && (
                 <a
                   href={meta.file_url}

frontend/src/lib/browserBackgroundPlay.dom.test.ts

@@ -0,0 +1,59 @@
+// @vitest-environment jsdom
+//
+// exposeVideoToBackgroundPlay: Brave iOS's background play hooks only a <video> that shows up as a
+// MutationObserver addedNode itself. A video mounted inside a new wrapper in one go never does — this
+// locks that the helper makes it one, once per element, without moving it.
+import { describe, it, expect } from "vitest";
+import { exposeVideoToBackgroundPlay } from "./browserBackgroundPlay";
+
+// Brave's detection rule, re-implemented: count addedNodes that ARE a <video>.
+async function videosSeenWhile(act: () => void): Promise<number> {
+  let seen = 0;
+  const observer = new MutationObserver((records) => {
+    for (const r of records) r.addedNodes.forEach((n) => n instanceof HTMLVideoElement && seen++);
+  });
+  observer.observe(document, { childList: true, subtree: true });
+  act();
+  await Promise.resolve(); // MutationObserver callbacks are microtasks
+  observer.disconnect();
+  return seen;
+}
+
+function mountWrapped(): { wrapper: HTMLDivElement; video: HTMLVideoElement } {
+  const wrapper = document.createElement("div");
+  const before = document.createElement("span");
+  const video = document.createElement("video");
+  const after = document.createElement("span");
+  wrapper.append(before, video, after);
+  return { wrapper, video };
+}
+
+describe("exposeVideoToBackgroundPlay", () => {
+  it("a video mounted inside its wrapper is invisible to the rule until exposed", async () => {
+    const { wrapper, video } = mountWrapped();
+    expect(await videosSeenWhile(() => document.body.append(wrapper))).toBe(0);
+    expect(await videosSeenWhile(() => exposeVideoToBackgroundPlay(video))).toBe(1);
+    wrapper.remove();
+  });
+
+  it("keeps the video exactly where it was", () => {
+    const { wrapper, video } = mountWrapped();
+    document.body.append(wrapper);
+    exposeVideoToBackgroundPlay(video);
+    expect([...wrapper.children].map((c) => c.tagName)).toEqual(["SPAN", "VIDEO", "SPAN"]);
+    wrapper.remove();
+  });
+
+  it("acts once per element, so a ref callback running on every render adds nothing", async () => {
+    const { wrapper, video } = mountWrapped();
+    document.body.append(wrapper);
+    exposeVideoToBackgroundPlay(video);
+    expect(await videosSeenWhile(() => exposeVideoToBackgroundPlay(video))).toBe(0);
+    wrapper.remove();
+  });
+
+  it("ignores null and a detached element", () => {
+    expect(() => exposeVideoToBackgroundPlay(null)).not.toThrow();
+    expect(() => exposeVideoToBackgroundPlay(document.createElement("video"))).not.toThrow();
+  });
+});

frontend/src/lib/browserBackgroundPlay.ts

@@ -0,0 +1,23 @@
+// Brave iOS keeps a web <video> playing when the browser leaves the foreground (Settings → Media → "Enable
+// Background Audio") by re-playing a video the OS paused. But it only hooks the <video> elements it SEES:
+// those present at document start, or a MutationObserver addedNode that IS a <video> (brave-core
+// ios/browser/web/media/resources/media_backgrounding.ts). React inserts a player's <video> inside its
+// freshly mounted wrapper in one go, so the video itself is never an added node and Brave never hooks it —
+// measured on iPad Brave 2026-09-14: the shared video stopped the moment the app was left; inserted as a
+// node of its own it kept playing, locked screen included.
+//
+// Re-inserting the element at its own position makes it an added node without changing the DOM React
+// manages. Playback is not interrupted: a media element removed and re-inserted within the same task is
+// back in the document by the next stable state, so the spec's pause-on-removal never runs.
+//
+// Only a <video> needs this: an <audio> already keeps playing in the background on its own.
+
+const exposed = new WeakSet<HTMLVideoElement>();
+
+/** Make a mounted <video> visible to the browser's background-play hook. Idempotent per element, so it is
+ *  safe from a ref callback that React calls on every render. */
+export function exposeVideoToBackgroundPlay(video: HTMLVideoElement | null): void {
+  if (!video || exposed.has(video) || !video.parentNode) return;
+  exposed.add(video);
+  video.parentNode.insertBefore(video, video.nextSibling);
+}

frontend/src/lib/storage.ts

@@ -65,6 +65,9 @@ export const LS = {
   notifSettings: "siftlode.notifSettings",
   onboardingDismissed: "siftlode.onboarding.dismissed",
   seenVersion: "siftlode.seenVersion",
+  // The public /watch page's repeat toggle ("0" = off; on by default). Browser-wide, NOT per account:
+  // that page runs outside the app, with no account at all.
+  watchRepeat: "siftlode.watchRepeat",
   chatDock: (userId: number) => `siftlode.chatDock.${userId}`,
 } as const;
 

frontend/src/lib/watchBackgroundAudio.ts

@@ -1,156 +0,0 @@
-// Background sound for a shared VIDEO on iPad — PROTOTYPE, dev only (improvement/watch-background-audio).
-//
-// iPadOS WebKit (every iPad browser, Brave included) stops a <video> the moment the browser leaves the
-// foreground, but lets an <audio> keep playing. Measured on iPad Brave 2026-09-14 with Brave's own
-// "Enable Background Audio" on: the mp3 share kept playing in another app, the h264 share stopped at once.
-// A page cannot simply START the sound when it is backgrounded (iOS allows starting playback only from a
-// tap), so two ways to have an <audio> already in hand are tried side by side:
-//
-//   "a" — the SOUND always comes from a hidden <audio> on the same file and the <video> runs muted,
-//         following it. Backgrounded, only the picture stops; back in front, the picture catches up.
-//   "b" — the <video> plays with its own sound; an <audio> is unlocked by the start tap and takes over
-//         from the same second when the page is backgrounded, handing back when it returns.
-//
-// Both need the start tap to call play() synchronously (startPlayback), so iOS counts it as the user's.
-//
-//   "c" — no audio trick at all: the <video> is inserted as a node of its own into an already-mounted
-//         wrapper. Brave iOS's background play (brave-core ios/browser/web/media/resources/
-//         media_backgrounding.ts) restarts a <video> the OS paused, but it only hooks videos present at
-//         document start or added as a MutationObserver addedNode that IS a video — the page used to
-//         insert the video inside a new wrapper in one go, so Brave never saw it. Brave-only by nature.
-
-export type AudioMode = "a" | "b";
-export type BackgroundMode = AudioMode | "c";
-
-export function readBackgroundMode(search: string): BackgroundMode | null {
-  const v = new URLSearchParams(search).get("bg");
-  return v === "a" || v === "b" || v === "c" ? v : null;
-}
-
-/** The start tap. Must run inside the click handler: iOS allows audible playback only from a gesture. */
-export function startPlayback(mode: AudioMode, video: HTMLVideoElement, audio: HTMLAudioElement) {
-  audio.currentTime = video.currentTime;
-  if (mode === "a") {
-    video.muted = true;
-    void audio.play();
-    void video.play();
-    return;
-  }
-  // "b": unlock the audio element with a silent play/pause inside the gesture, then play the video.
-  audio.muted = true;
-  void audio.play().then(() => {
-    audio.pause();
-    audio.muted = false;
-  });
-  void video.play();
-}
-
-// The OS pauses the video when the page goes to the background, and the pause event can arrive before
-// visibilitychange. Decide what a pause meant only once that has had a moment to land.
-const SETTLE_MS = 250;
-const DRIFT_S = 0.3;
-
-/** Mode "a": the audio is the clock; the muted video follows it. Returns a cleanup. */
-export function followAudio(video: HTMLVideoElement, audio: HTMLAudioElement): () => void {
-  let timer: number | undefined;
-  const onVideoPlay = () => {
-    if (audio.paused) void audio.play();
-  };
-  const onVideoPause = () => {
-    window.clearTimeout(timer);
-    timer = window.setTimeout(() => {
-      // A pause while the page is in front is the user's; one while hidden is the OS stopping the picture.
-      if (!document.hidden && video.paused) audio.pause();
-    }, SETTLE_MS);
-  };
-  // Our own catch-up seeks on the video must NOT be copied back onto the audio: that loop re-seeked the
-  // sound on every drift correction (an audible skip), and in WebKit it sent both back seconds on return.
-  // Only a seek the user makes on the video's controls moves the sound.
-  let ownSeek = false;
-  const syncVideo = () => {
-    ownSeek = true;
-    video.currentTime = audio.currentTime;
-  };
-  const onVideoSeeking = () => {
-    if (!ownSeek) audio.currentTime = video.currentTime;
-  };
-  const onVideoSeeked = () => {
-    ownSeek = false;
-  };
-  const onVideoVolume = () => {
-    // The controls' mute button acts on the sound; the picture itself always stays muted.
-    if (!video.muted) {
-      audio.muted = !audio.muted;
-      video.muted = true;
-    }
-  };
-  const onAudioEnded = () => video.pause();
-  const onVisible = () => {
-    if (document.hidden) return;
-    syncVideo();
-    if (!audio.paused) void video.play();
-  };
-  const drift = window.setInterval(() => {
-    if (!document.hidden && !audio.paused && !video.seeking) {
-      if (Math.abs(video.currentTime - audio.currentTime) > DRIFT_S) syncVideo();
-    }
-  }, 1000);
-
-  video.addEventListener("play", onVideoPlay);
-  video.addEventListener("pause", onVideoPause);
-  video.addEventListener("seeking", onVideoSeeking);
-  video.addEventListener("seeked", onVideoSeeked);
-  video.addEventListener("volumechange", onVideoVolume);
-  audio.addEventListener("ended", onAudioEnded);
-  document.addEventListener("visibilitychange", onVisible);
-  return () => {
-    window.clearTimeout(timer);
-    window.clearInterval(drift);
-    video.removeEventListener("play", onVideoPlay);
-    video.removeEventListener("pause", onVideoPause);
-    video.removeEventListener("seeking", onVideoSeeking);
-    video.removeEventListener("seeked", onVideoSeeked);
-    video.removeEventListener("volumechange", onVideoVolume);
-    audio.removeEventListener("ended", onAudioEnded);
-    document.removeEventListener("visibilitychange", onVisible);
-  };
-}
-
-/** Mode "b": the video plays with sound; the audio takes over while the page is hidden. Returns a cleanup. */
-export function handOverOnHide(video: HTMLVideoElement, audio: HTMLAudioElement): () => void {
-  // Whether the USER has the video playing. The OS's own pause on backgrounding must not clear it, so
-  // a pause only counts once it has settled with the page still in front.
-  let playing = !video.paused;
-  let timer: number | undefined;
-  const onVideoPlay = () => {
-    playing = true;
-  };
-  const onVideoPause = () => {
-    window.clearTimeout(timer);
-    timer = window.setTimeout(() => {
-      if (!document.hidden && video.paused) playing = false;
-    }, SETTLE_MS);
-  };
-  const onVisibility = () => {
-    if (document.hidden) {
-      if (!playing) return;
-      audio.currentTime = video.currentTime; // where the picture stopped, even if the OS paused it first
-      void audio.play();
-      return;
-    }
-    if (!audio.paused) {
-      video.currentTime = audio.currentTime;
-      audio.pause();
-      void video.play();
-    }
-  };
-  video.addEventListener("play", onVideoPlay);
-  video.addEventListener("pause", onVideoPause);
-  document.addEventListener("visibilitychange", onVisibility);
-  return () => {
-    window.clearTimeout(timer);
-    video.removeEventListener("play", onVideoPlay);
-    video.removeEventListener("pause", onVideoPause);
-    document.removeEventListener("visibilitychange", onVisibility);
-  };
-}