Release v1.11.1: builds, docs, fixes

Bump release to v1.11.1, add packaged extension builds and update metadata. Includes new Chrome/Firefox extension artifacts and a Firefox updates manifest for auto-updates, and updates the distributed userscript version. Changelog: add detailed 1.11.1 notes (volume link/sync improvements, adaptive volume tweaks, stability fixes, AudioContext recovery and proxy fallbacks, subtitle cleaning and mobile positioning, YouTube Shorts lifecycle fixes, mobile download fallbacks, various site fixes). Docs: update README (EN/RU) — remove OrangeMonkey references, add Opera guidance link and adjust badges/instructions; add .gitignore entries for dist-ext directories. Source: add extension.zip and new volumeLink util; multiple code updates across audioDownloader, core (lifecycle, translation, event impl), extension background/prelude, UI/views, subtitles, styles and video handling to implement fixes and improvements described in the changelog.
2026-07-09 16:00:11 +00:00 · 2026-02-17 22:12:48 +04:00 · 2026-02-17 22:12:48 +04:00 · e110bcd54b
commit e110bcd54b
parent 3a59dfcb34
50 changed files with 2890 additions and 4081 deletions
--- a/.gitignore
+++ b/.gitignore
@ -3,6 +3,8 @@ arch*.txt
 dist/test-ui.user.js
 dist/*.txt
 dist/main.user.js
+dist-ext/chrome/
+dist-ext/firefox/

 src/localization/locales/generate_phrase.py
 src/localization/locales/regenerate_locales.py
--- a/README-EN.md
+++ b/README-EN.md
@ -9,7 +9,6 @@
 [adguard-userscripts]: https://kb.adguard.com/en/general/userscripts#supported-apps
 [firemonkey-link]: https://erosman.github.io/firemonkey/
 [greasemonkey-link]: https://github.com/greasemonkey/greasemonkey
-[orangemonkey-link]: https://chromewebstore.google.com/detail/OrangeMonkey/ekmeppjgajofkpiofbebgcbohbmfldaf
 [user-js-and-css-link]: https://tenrabbits.github.io/user-js-css-docs/

 <!-- FAQs / Wiki -->
@ -17,6 +16,7 @@
 [firemonkey-how-to]: https://github.com/ilyhalight/voice-over-translation/wiki/%5BEN%5D-FAQ#%D0%BA%D0%B0%D0%BA-%D0%B8%D1%81%D0%BF%D0%BE%D0%BB%D1%8C%D0%B7%D0%BE%D0%B2%D0%B0%D1%82%D1%8C-%D1%80%D0%B0%D1%81%D1%88%D0%B8%D1%80%D0%B5%D0%BD%D0%B8%D0%B5-%D1%81-firemonkey
 [user-js-and-css-how-to]: https://github.com/ilyhalight/voice-over-translation/wiki/%5BEN%5D-FAQ#%D0%BA%D0%B0%D0%BA-%D0%B8%D1%81%D0%BF%D0%BE%D0%BB%D1%8C%D0%B7%D0%BE%D0%B2%D0%B0%D1%82%D1%8C-%D1%80%D0%B0%D1%81%D1%88%D0%B8%D1%80%D0%B5%D0%BD%D0%B8%D0%B5-%D1%81-user-js-and-css
 [devmode-enable]: https://www.tampermonkey.net/faq.php#Q209
+[opera-search-results-access]: https://help.opera.com/en/extensions/content-scripts/
 [vot-faq]: https://github.com/ilyhalight/voice-over-translation/wiki/%5BEN%5D-FAQ
 [vot-supported-sites]: https://github.com/ilyhalight/voice-over-translation/wiki/%5BEN%5D-Supported-sites
 [vot-wiki]: https://github.com/ilyhalight/voice-over-translation/wiki
@ -56,8 +56,8 @@

 <!-- Content -->

-[![ru][badge-ru]][vot-readme-en]
-[![en][badge-en]][vot-readme-ru]
+[![ru][badge-ru]][vot-readme-ru]
+[![en][badge-en]][vot-readme-en]

 > [!CAUTION]
 > Before creating Issues, we strongly recommend that you read the [FAQ][vot-faq] section and with existing [Issues][vot-issues].
@ -71,12 +71,12 @@ Voice-over translation is now available beyond [Yandex Browser][yabrowser-link].
 > [!WARNING]
 > **Important for Tampermonkey 5.2+ (MV3) users:**
 > In **Chromium**-based browsers (Chrome, Edge, Brave, Vivaldi, etc.) you must:
-> 1. Open the extensions page (`chrome://extensions`) and enable **"Developer mode"**.
+> 1. Open the extensions page (`chrome://extensions`) and enable **"Developer mode"** (details in [Tampermonkey documentation][devmode-enable]).
 > 2. If you use **Chromium 138+**, open extension details and enable **"Allow User Scripts"**.
 >
 > **For Opera users:**
 > 1. Use **[Violentmonkey][violentmonkey-opera]** instead of Tampermonkey.
-> 2. In the extension settings, enable **"Allow access to search page results"**; otherwise the script will not work.
+> 2. In the extension settings, enable **"Allow access to search page results"** (Opera guide: [where to find this setting][opera-search-results-access]); otherwise the script will not work.

 1. Install a userscript manager: **[Tampermonkey][tampermonkey-link]** (or [Violentmonkey][violentmonkey-opera] for Opera)
 2. **[Install the script][vot-dist]**
@ -264,7 +264,7 @@ The extension has been tested in the following browsers:
 | ✅     | MS Edge                   | v106.0.1370.34       | Windows, Linux          | Tampermonkey (MV2)                                                                          |
 | ✅     | Cent Browser              | v4.3.9.248           | Windows                 | Tampermonkey (MV2)                                                                          |
 | ✅     | Cent Browser Beta         | v5.0.1002.182        | Windows                 | Tampermonkey (MV2)                                                                          |
-| ✅     | Google Chrome             | v106                 | Windows, MacOS, Linux   | Tampermonkey (MV2), Tampermonkey (MV3), Violentmonkey, OrangeMonkey, User Javascript and CSS |
+| ✅     | Google Chrome             | v106                 | Windows, MacOS, Linux   | Tampermonkey (MV2), Tampermonkey (MV3), Violentmonkey, User Javascript and CSS |
 | ✅     | Opera GX (LVL4)           | core91               | Windows                 | Violentmonkey                                                                               |
 | ✅     | Opera GX (LVL5)           | core109              | Windows                 | Violentmonkey                                                                               |
 | ✅     | Opera                     | v92.0.4561.43        | Windows                 | Violentmonkey                                                                               |
@ -291,7 +291,6 @@ Tested in the following userscript manager extensions:
 | ❔                        | Any     | [AdGuard Userscripts][adguard-userscripts]     |
 | [Install guide][firemonkey-how-to] | Firefox | [Firemonkey][firemonkey-link]                  |
 | ✅                        | Firefox | [Greasemonkey][greasemonkey-link]              |
-| ⚠️²                       | Any     | [OrangeMonkey][orangemonkey-link]              |
 | [Install guide][user-js-and-css-how-to]¹ | Any     | [User Javascript and CSS][user-js-and-css-link] |

 ¹ - Works in proxy mode, but the important "Use audio download" feature is unavailable due to missing `unsafeWindow` API, which can cause issues with newly requested translations.
--- a/README.md
+++ b/README.md
@ -9,7 +9,6 @@
 [adguard-userscripts]: https://kb.adguard.com/en/general/userscripts#supported-apps
 [firemonkey-link]: https://erosman.github.io/firemonkey/
 [greasemonkey-link]: https://github.com/greasemonkey/greasemonkey
-[orangemonkey-link]: https://chromewebstore.google.com/detail/OrangeMonkey/ekmeppjgajofkpiofbebgcbohbmfldaf
 [user-js-and-css-link]: https://tenrabbits.github.io/user-js-css-docs/ru/

 <!-- FAQs / Wiki -->
@ -17,6 +16,7 @@
 [firemonkey-how-to]: https://github.com/ilyhalight/voice-over-translation/wiki/%5BRU%5D-FAQ#%D0%BA%D0%B0%D0%BA-%D0%B8%D1%81%D0%BF%D0%BE%D0%BB%D1%8C%D0%B7%D0%BE%D0%B2%D0%B0%D1%82%D1%8C-%D1%80%D0%B0%D1%81%D1%88%D0%B8%D1%80%D0%B5%D0%BD%D0%B8%D0%B5-%D1%81-firemonkey
 [user-js-and-css-how-to]: https://github.com/ilyhalight/voice-over-translation/wiki/%5BRU%5D-FAQ#%D0%BA%D0%B0%D0%BA-%D0%B8%D1%81%D0%BF%D0%BE%D0%BB%D1%8C%D0%B7%D0%BE%D0%B2%D0%B0%D1%82%D1%8C-%D1%80%D0%B0%D1%81%D1%88%D0%B8%D1%80%D0%B5%D0%BD%D0%B8%D0%B5-%D1%81-user-js-and-css
 [devmode-enable]: https://www.tampermonkey.net/faq.php#Q209
+[opera-search-results-access]: https://help.opera.com/en/extensions/content-scripts/
 [vot-faq]: https://github.com/ilyhalight/voice-over-translation/wiki/%5BRU%5D-FAQ
 [vot-supported-sites]: https://github.com/ilyhalight/voice-over-translation/wiki/%5BRU%5D-Supported-sites
 [vot-wiki]: https://github.com/ilyhalight/voice-over-translation/wiki
@ -56,8 +56,8 @@

 <!-- Content -->

-[![en][badge-en]][vot-readme-ru]
-[![ru][badge-ru]][vot-readme-en]
+[![en][badge-en]][vot-readme-en]
+[![ru][badge-ru]][vot-readme-ru]

 > [!CAUTION]
 > Перед созданием Issues настоятельно рекомендуем ознакомиться с разделом [FAQ][vot-faq] и уже существующими [Issues][vot-issues].
@ -71,12 +71,12 @@
 > [!WARNING]
 > **Важно для пользователей Tampermonkey 5.2+ (MV3):**
 > В браузерах на движке **Chromium** (Chrome, Edge, Brave, Vivaldi и др.) необходимо:
-> 1. Открыть страницу расширений (`chrome://extensions`) и включить **«Режим разработчика»**.
+> 1. Открыть страницу расширений (`chrome://extensions`) и включить **«Режим разработчика»** (подробности в [документации Tampermonkey][devmode-enable]).
 > 2. Если движок **Chromium версии 138+**, в «Сведениях» расширения включить **«Разрешить пользовательские скрипты»**.
 >
 > **Пользователям Opera:**
 > 1. Используйте **[Violentmonkey][violentmonkey-opera]** вместо Tampermonkey.
-> 2. В настройках расширения обязательно включите **«Разрешить доступ к результатам на странице поиска»**, иначе скрипт не будет работать.
+> 2. В настройках расширения обязательно включите **«Разрешить доступ к результатам на странице поиска»** (гайд от Opera: [как найти эту настройку][opera-search-results-access]), иначе скрипт не будет работать.

 1. Установите загрузчик юзерскриптов: **[Tampermonkey][tampermonkey-link]** (или [Violentmonkey][violentmonkey-opera] для Opera)
 2. **[«Установить скрипт»][vot-dist]**
@ -264,7 +264,7 @@ bun install
 | ✅     | MS Edge                   | v106.0.1370.34       | Windows, Linux          | Tampermonkey (MV2)                                                                           |
 | ✅     | Cent Browser              | v4.3.9.248           | Windows                 | Tampermonkey (MV2)                                                                           |
 | ✅     | Cent Browser Beta         | v5.0.1002.182        | Windows                 | Tampermonkey (MV2)                                                                           |
-| ✅     | Google Chrome             | v106                 | Windows, MacOS, Linux   | Tampermonkey (MV2), Tampermonkey (MV3), Violentmonkey, OrangeMonkey, User Javascript and CSS |
+| ✅     | Google Chrome             | v106                 | Windows, MacOS, Linux   | Tampermonkey (MV2), Tampermonkey (MV3), Violentmonkey, User Javascript and CSS |
 | ✅     | Opera GX (LVL4)           | core91               | Windows                 | Violentmonkey                                                                                |
 | ✅     | Opera GX (LVL5)           | core109              | Windows                 | Violentmonkey                                                                                |
 | ✅     | Opera                     | v92.0.4561.43        | Windows                 | Violentmonkey                                                                                |
@ -291,7 +291,6 @@ bun install
 | ❔                        | Любой   | [AdGuard Userscripts][adguard-userscripts]      |
 | [Гайд по установке][firemonkey-how-to] | Firefox | [Firemonkey][firemonkey-link]                   |
 | ✅                        | Firefox | [Greasemonkey][greasemonkey-link]               |
-| ⚠️²                       | Любой   | [OrangeMonkey][orangemonkey-link]               |
 | [Гайд по установке][user-js-and-css-how-to]¹ | Любой   | [User Javascript and CSS][user-js-and-css-link] |

 ¹ - Работает в режиме проксирования, важная функция «Использовать загрузку аудио» недоступна из-за отсутствия `unsafeWindow` API, что может приводить к проблемам с переводом новых видео.
--- a/changelog.md
+++ b/changelog.md
@ -1,4 +1,20 @@
-# 1.11.0
+# 1.11.1
+
+- Улучшена работа настройки "Связать громкость перевода и видео": переработана дельта-синхронизация слайдеров, устранены дрейф громкости и зацикливание при внешних изменениях громкости плеера
+- Доработана "Адаптивная громкость": улучшен анализ речи в переведенной дорожке и устранен конфликт с режимом синхронизации громкости
+- Повышена стабильность запуска/остановки перевода: устранены гонки при повторном старте, смене видео и переключении прокси
+- Улучшено восстановление воспроизведения перевода: добавлено корректное возобновление `AudioContext` и fallback на прямой URL при ошибке проксированной аудиоссылки
+- Исправлена обработка субтитров: удаляются служебные HTML/таймкоды и объединяются дублирующиеся короткие реплики (особенно заметно на VK)
+- Улучшено позиционирование субтитров на мобильных устройствах с учетом `safe-area`
+- Исправлена обработка смены видео на YouTube Shorts и дедупликация lifecycle-событий, что снижает вероятность повторной инициализации
+- Улучшена загрузка переведенной дорожки на мобильных устройствах (share/download fallback) и резервные сценарии скачивания
+- Добавлен Firefox updates manifest для автообновлений
+- Исправлена нестабильная работа в iOS/macOS
+- Исправлена ошибка на Udemy: кнопка перевода быстро исчезала и показывалась ошибка `No video ID found` (#1510)
+- Исправлена работа на VK.com (#1512)
+- Исправлена инициализация на YouTube (#1521)
+
+# 1.11.0

 - Добавлена поддержка ZDF (#1443), Niconico (#1188), Weibo, Xhamster (#1260), Spankbang (#1049), Rule34video (#984), Picarto (#960), Olympics Replay (#714) и Bilibili TV (#1151)
 - Добавлена поддержка `disk.360.yandex.ru` для Yandex Disk
--- a/dist-ext/vot-extension-chrome-1.11.0.crx
+++ b/dist-ext/vot-extension-chrome-1.11.0.crx
--- a/dist-ext/vot-extension-chrome-1.11.1.crx
+++ b/dist-ext/vot-extension-chrome-1.11.1.crx
--- a/dist-ext/vot-extension-firefox-1.11.0.xpi
+++ b/dist-ext/vot-extension-firefox-1.11.0.xpi
--- a/dist-ext/vot-extension-firefox-1.11.1.xpi
+++ b/dist-ext/vot-extension-firefox-1.11.1.xpi
--- a/dist-ext/vot-extension-firefox-updates.json
+++ b/dist-ext/vot-extension-firefox-updates.json
@ -0,0 +1,12 @@
+{
+   "addons": {
+      "vot-extension@firefox": {
+         "updates": [
+            {
+               "version": "1.11.1",
+               "update_link": "https://raw.githubusercontent.com/ilyhalight/voice-over-translation/master/dist-ext/vot-extension-firefox-1.11.1.xpi"
+            }
+         ]
+      }
+   }
+}
--- a/dist/vot-min.user.js
+++ b/dist/vot-min.user.js
--- a/dist/vot.user.js
+++ b/dist/vot.user.js
--- a/package-lock.json
+++ b/package-lock.json
--- a/src/audioDownloader/index.ts
+++ b/src/audioDownloader/index.ts
@ -38,7 +38,7 @@ async function handleCommonAudioDownloadRequest({
      throw new Error("Audio downloader. Empty audio");
    }

-    audioDownloader.onDownloadedAudio.dispatch(translationId, {
+    await audioDownloader.onDownloadedAudio.dispatchAsync(translationId, {
      videoId,
      fileId,
      audioData: value,
@ -52,14 +52,17 @@ async function handleCommonAudioDownloadRequest({
      throw new Error("Audio downloader. Empty audio");
    }

-    audioDownloader.onDownloadedPartialAudio.dispatch(translationId, {
-      videoId,
-      fileId,
-      audioData: audioChunk,
-      version: 1,
-      index,
-      amount: mediaPartsLength,
-    });
+    await audioDownloader.onDownloadedPartialAudio.dispatchAsync(
+      translationId,
+      {
+        videoId,
+        fileId,
+        audioData: audioChunk,
+        version: 1,
+        index,
+        amount: mediaPartsLength,
+      },
+    );

    index++;
  }
--- a/src/audioDownloader/strategies/webApiGetAllGeneratingUrlsData/index.ts
+++ b/src/audioDownloader/strategies/webApiGetAllGeneratingUrlsData/index.ts
@ -230,16 +230,18 @@ export async function getAudioFromWebApiWithReplacedFetch({
  const serializedInit = serializeRequestInit(requestInfo);
  const fallbackInit = deserializeRequestInit(serializedInit);
  const finalRequestInit = normalizeRequestInit(requestInit, fallbackInit);
+  const chunkParts = returnByParts
+    ? getChunkRangesPartsFromAdaptiveFormat(adaptiveFormat)
+    : null;

  return {
    fileId: makeFileId(STRATEGY_TYPE, itag, adaptiveFormat.contentLength),
-    mediaPartsLength: returnByParts
-      ? getChunkRangesPartsFromAdaptiveFormat(adaptiveFormat).length
-      : 1,
+    mediaPartsLength: chunkParts?.length ?? 1,
    async *getMediaBuffers(): AsyncGenerator<Uint8Array> {
      if (returnByParts) {
-        const chunkParts =
-          getChunkRangesPartsFromAdaptiveFormat(adaptiveFormat);
+        if (!chunkParts?.length) {
+          throw new Error("Audio downloader. WEB API. Empty chunk parts");
+        }
        for (const part of chunkParts) {
          const { media, url, isAcceptableLast } =
            await fetchMediaWithMetaByChunkRanges(
--- a/src/bootstrap/videoObserverBinding.ts
+++ b/src/bootstrap/videoObserverBinding.ts
@ -4,6 +4,8 @@ import type { VideoObserver } from "../utils/VideoObserver";
 type VideoHandlerLike = {
  init(): Promise<void>;
  setCanPlay(): Promise<void>;
+  getVideoData(): Promise<unknown>;
+  videoData?: unknown;
  release(): Promise<void> | void;
 };

--- a/src/core/eventImpl.ts
+++ b/src/core/eventImpl.ts
@ -35,6 +35,32 @@ export class EventImpl<Args extends unknown[] = unknown[]> {
    }
  }

+  async dispatchAsync(...args: Args): Promise<void> {
+    const pending: Promise<void>[] = [];
+
+    for (const handler of this.listeners) {
+      try {
+        const result = handler(...args);
+        if (result && typeof (result as Promise<void>).then === "function") {
+          pending.push(Promise.resolve(result));
+        }
+      } catch (exception) {
+        console.error("[VOT]", exception);
+      }
+    }
+
+    if (!pending.length) {
+      return;
+    }
+
+    const settled = await Promise.allSettled(pending);
+    for (const item of settled) {
+      if (item.status === "rejected") {
+        console.error("[VOT]", item.reason);
+      }
+    }
+  }
+
  clear(): void {
    this.listeners.clear();
  }
--- a/src/core/lifecycleShared.ts
+++ b/src/core/lifecycleShared.ts
@ -1,6 +1,6 @@
 export type LifecycleTranslationResetHost = {
  videoData?: unknown;
-  stopTranslation(): void;
+  stopTranslation(): void | Promise<void>;
  resetSubtitlesWidget(): void;
 };

--- a/src/core/translationHandler.ts
+++ b/src/core/translationHandler.ts
@ -282,13 +282,18 @@ export class VOTTranslationHandler {
        return;
      }

-      timeoutId = setTimeout(() => {
+      timeoutId = setTimeout(async () => {
        if (signal.aborted) {
          onAbort();
          return;
        }
        cleanup();
-        void fn().then(resolve, reject);
+        try {
+          const result = await fn();
+          resolve(result);
+        } catch (error) {
+          reject(error);
+        }
      }, delayMs);

      // Keep old behavior: allow caller to clear retries via the host.
--- a/src/core/videoLifecycleController.ts
+++ b/src/core/videoLifecycleController.ts
@ -23,7 +23,7 @@ interface VideoLifecycleHost {
  site: ServiceConf<VideoService>;
  container: HTMLElement;
  firstPlay: boolean;
-  stopTranslation(): void;
+  stopTranslation(): void | Promise<void>;
  resetSubtitlesWidget(): void;
  uiManager: LifecycleUIManager;
  getVideoData(): Promise<VideoData | undefined>;
@ -54,12 +54,9 @@ export class VideoLifecycleController {
  private readonly host: VideoLifecycleHost;
  private lifecycleGeneration = 0;
  private lastSetCanPlaySourceKey = "";
+  private activeSetCanPlaySourceKey = "";
  private setCanPlayRequested = false;
  private setCanPlayLoopPromise?: Promise<void>;
-  private inFlightVideoDataRequest?: {
-    sourceKey: string;
-    promise: Promise<VideoData | undefined>;
-  };

  constructor(host: VideoLifecycleHost) {
    this.host = host;
@ -109,12 +106,20 @@ export class VideoLifecycleController {
  teardown() {
    this.setCanPlayRequested = false;
    this.invalidateActiveSession("teardown");
-    this.inFlightVideoDataRequest = undefined;
  }

  private getCurrentSourceKey(): string {
-    const src = this.host.video.currentSrc || this.host.video.src || "";
    const hasSrcObject = this.host.video.srcObject ? "1" : "0";
+    if (this.host.site.host === "youtube") {
+      const path = globalThis.location.pathname;
+      if (path.startsWith("/shorts/")) {
+        // Shorts frequently rotate blob src values for the same logical video.
+        // Use pathname to keep lifecycle keys stable and avoid duplicate runs.
+        return `${globalThis.location.origin}${path}||${hasSrcObject}`;
+      }
+    }
+
+    const src = this.host.video.currentSrc || this.host.video.src || "";
    return `${globalThis.location.href}||${src}||${hasSrcObject}`;
  }

@ -141,7 +146,19 @@ export class VideoLifecycleController {
  async setCanPlay() {
    this.setCanPlayRequested = true;
    if (this.setCanPlayLoopPromise !== undefined) {
-      this.invalidateActiveSession("setCanPlay superseded by a newer trigger");
+      const incomingSourceKey = this.getCurrentSourceKey();
+      if (
+        this.activeSetCanPlaySourceKey &&
+        incomingSourceKey !== this.activeSetCanPlaySourceKey
+      ) {
+        this.invalidateActiveSession(
+          "setCanPlay source changed while previous trigger is running",
+        );
+      } else {
+        debug.log("[VideoLifecycle] setCanPlay deduplicated for same source", {
+          sourceKey: incomingSourceKey,
+        });
+      }
      return await this.setCanPlayLoopPromise;
    }

@ -168,42 +185,65 @@ export class VideoLifecycleController {
      this.host.videoData?.videoId &&
      sourceKey === this.lastSetCanPlaySourceKey
    ) {
+      debug.log("[VideoLifecycle] setCanPlay deduplicated for same source", {
+        sourceKey,
+      });
      return;
    }

+    try {
+      this.host.videoData = await this.host.getVideoData();
+    } catch (err) {
+      debug.log(
+        `[VideoLifecycle] getVideoData failed for source ${sourceKey}`,
+        err,
+      );
+      this.host.videoData = undefined;
+      hideLifecycleOverlay(this.host.uiManager.votOverlayView, {
+        hideMenu: true,
+      });
+      return;
+    }
+
+    this.activeSetCanPlaySourceKey = sourceKey;
    const currentId = this.startSession(`setCanPlay (source: ${sourceKey})`);
    debug.log(`[VideoLifecycle][session:${currentId}] setCanPlay started`, {
      sourceKey,
    });
-    this.lastSetCanPlaySourceKey = sourceKey;

-    await this.handleSrcChanged(currentId, sourceKey);
+    try {
+      await this.handleSrcChanged(currentId, sourceKey);

-    if (this.isStale(currentId)) {
-      debug.log(
-        `[VideoLifecycle][session:${currentId}] setCanPlay aborted after src change (active: ${this.lifecycleGeneration})`,
-      );
-      return;
+      if (this.isStale(currentId)) {
+        debug.log(
+          `[VideoLifecycle][session:${currentId}] setCanPlay aborted after src change (active: ${this.lifecycleGeneration})`,
+        );
+        return;
+      }
+
+      const autoSubtitlesPromise = this.runAutoSubtitlesIfEnabled(currentId);
+
+      await this.host.translationOrchestrator.runAutoTranslationIfEligible();
+      if (this.isStale(currentId)) {
+        debug.log(
+          `[VideoLifecycle][session:${currentId}] auto-translation result ignored (stale session)`,
+        );
+        return;
+      }
+
+      await autoSubtitlesPromise;
+      if (this.isStale(currentId)) {
+        debug.log(
+          `[VideoLifecycle][session:${currentId}] auto-subtitles result ignored (stale session)`,
+        );
+        return;
+      }
+      debug.log(`[VideoLifecycle][session:${currentId}] setCanPlay finished`);
+    } finally {
+      if (this.activeSetCanPlaySourceKey === sourceKey) {
+        this.activeSetCanPlaySourceKey = "";
+      }
    }
-
-    const autoSubtitlesPromise = this.runAutoSubtitlesIfEnabled(currentId);
-
-    await this.host.translationOrchestrator.runAutoTranslationIfEligible();
-    if (this.isStale(currentId)) {
-      debug.log(
-        `[VideoLifecycle][session:${currentId}] auto-translation result ignored (stale session)`,
-      );
-      return;
-    }
-
-    await autoSubtitlesPromise;
-    if (this.isStale(currentId)) {
-      debug.log(
-        `[VideoLifecycle][session:${currentId}] auto-subtitles result ignored (stale session)`,
-      );
-      return;
-    }
-    debug.log(`[VideoLifecycle][session:${currentId}] setCanPlay finished`);
  }

  private async runAutoSubtitlesIfEnabled(sessionId: number): Promise<void> {
@ -221,28 +261,6 @@ export class VideoLifecycleController {
    }
  }

-  private async getVideoDataSingleFlight(
-    sourceKey: string,
-  ): Promise<VideoData | undefined> {
-    const inFlight = this.inFlightVideoDataRequest;
-    if (inFlight?.sourceKey === sourceKey) {
-      debug.log(
-        `[VideoLifecycle] reusing in-flight getVideoData for source ${sourceKey}`,
-      );
-      return await inFlight.promise;
-    }
-
-    const promise = this.host.getVideoData();
-    this.inFlightVideoDataRequest = { sourceKey, promise };
-    try {
-      return await promise;
-    } finally {
-      if (this.inFlightVideoDataRequest?.promise === promise) {
-        this.inFlightVideoDataRequest = undefined;
-      }
-    }
-  }
-
  async handleSrcChanged(callId?: number, expectedSourceKey?: string) {
    const sessionId =
      typeof callId === "number"
@ -252,9 +270,6 @@ export class VideoLifecycleController {
      typeof expectedSourceKey === "string" && expectedSourceKey.length > 0
        ? expectedSourceKey
        : this.getCurrentSourceKey();
-    if (typeof callId !== "number") {
-      this.lastSetCanPlaySourceKey = sourceKey;
-    }

    if (this.shouldAbortHandleSrcChanged(sessionId, "before start")) {
      return;
@ -281,11 +296,6 @@ export class VideoLifecycleController {
      this.host.container = nextContainer;
    }

-    if (this.shouldSkipYouTubeSource()) {
-      hideLifecycleOverlay(overlayView, { hideMenu: true });
-      return;
-    }
-
    if (this.shouldAbortHandleSrcChanged(sessionId, "before getVideoData")) {
      return;
    }
@ -295,33 +305,10 @@ export class VideoLifecycleController {
    overlayView.votButton.opacity = 1;
    this.host.queueOverlayAutoHide?.();

-    let nextVideoData: VideoData | undefined;
-    try {
-      nextVideoData =
-        typeof sourceKey === "string" && sourceKey
-          ? await this.getVideoDataSingleFlight(sourceKey)
-          : await this.host.getVideoData();
-    } catch (err) {
-      debug.log(
-        `[VideoLifecycle][session:${sessionId}] getVideoData failed, hiding overlay`,
-        err,
-      );
-      if (
-        this.shouldAbortHandleSrcChanged(sessionId, "after getVideoData error")
-      ) {
-        return;
-      }
-      this.host.videoData = undefined;
-      hideLifecycleOverlay(overlayView, { hideMenu: true });
-      return;
-    }
-
    if (this.shouldAbortHandleSrcChanged(sessionId, "after getVideoData")) {
      return;
    }

-    this.host.videoData = nextVideoData;
-
    if (!this.host.videoData?.videoId) {
      debug.log(
        `[VideoLifecycle][session:${sessionId}] No videoId resolved, hiding overlay`,
@ -352,23 +339,7 @@ export class VideoLifecycleController {
    overlayView.votButton.container.hidden = false;
    overlayView.votButton.opacity = 1;
    this.host.queueOverlayAutoHide?.();
+    this.lastSetCanPlaySourceKey = sourceKey;
    debug.log(`[VideoLifecycle][session:${sessionId}] src handling finished`);
  }
-
-  private shouldSkipYouTubeSource() {
-    if (this.host.site.host !== "youtube") return false;
-
-    const isYouTubeDomain =
-      /(^|\.)youtube(?:-nocookie|kids)?\.com$/.test(
-        globalThis.location.hostname,
-      ) || globalThis.location.hostname === "youtube.googleapis.com";
-
-    const path = globalThis.location.pathname;
-    const pathOkForYouTube =
-      path === "/watch" ||
-      path.startsWith("/embed/") ||
-      path.startsWith("/shorts/");
-
-    return isYouTubeDomain && !pathOkForYouTube;
-  }
 }
--- a/src/core/videoManager.ts
+++ b/src/core/videoManager.ts
@ -1,9 +1,4 @@
-import type {
-  VideoData as CoreVideoData,
-  VideoDataSubtitle,
-} from "@vot.js/core/types/client";
 import YoutubeHelper from "@vot.js/ext/helpers/youtube";
-import type { VideoService } from "@vot.js/ext/types/service";
 import { getVideoData } from "@vot.js/ext/utils/videoData";
 import votConfig from "@vot.js/shared/config";
 import { availableLangs } from "@vot.js/shared/consts";
@ -39,25 +34,8 @@ const FORCED_DETECTED_LANGUAGE_BY_HOST: Record<string, RequestLang> = {

 const YT_VOLUME_NOW_SELECTOR = ".ytp-volume-panel [aria-valuenow]";

-type RawVideoData = CoreVideoData<VideoService>;
-
-type SubtitleLike = Pick<
-  VideoDataSubtitle,
-  "language" | "translatedFromLanguage"
->;
-
 type ResolvedRequestLang = Exclude<RequestLang, "auto">;

-type DetectSourceVideoData = Pick<
-  RuntimeVideoData,
-  | "videoId"
-  | "detectedLanguage"
-  | "responseLanguage"
-  | "title"
-  | "localizedTitle"
-  | "description"
->;
-
 function pickFirstNonEmptyString(...values: unknown[]): string | undefined {
  for (const value of values) {
    if (typeof value !== "string") continue;
@ -78,61 +56,10 @@ function normalizeToRequestLang(value: unknown): RequestLang | undefined {

 function isResolvedLanguage(
  value: RequestLang | undefined,
-): value is Exclude<RequestLang, "auto"> {
+): value is ResolvedRequestLang {
  return Boolean(value && value !== "auto");
 }

-function inferLanguageFromSubtitles(
-  subtitles: unknown,
-): RequestLang | undefined {
-  if (!Array.isArray(subtitles) || subtitles.length === 0) {
-    return undefined;
-  }
-
-  const tracks = subtitles as SubtitleLike[];
-
-  // Prefer explicit source-language hints from translated tracks.
-  for (const track of tracks) {
-    const translatedFrom = normalizeToRequestLang(
-      track?.translatedFromLanguage,
-    );
-    if (isResolvedLanguage(translatedFrom)) {
-      return translatedFrom;
-    }
-  }
-
-  // Then prefer non-translated original subtitle tracks.
-  for (const track of tracks) {
-    if (track?.translatedFromLanguage) continue;
-    const language = normalizeToRequestLang(track?.language);
-    if (isResolvedLanguage(language)) {
-      return language;
-    }
-  }
-
-  // Last subtitles fallback: any concrete language track.
-  for (const track of tracks) {
-    const language = normalizeToRequestLang(track?.language);
-    if (isResolvedLanguage(language)) {
-      return language;
-    }
-  }
-
-  return undefined;
-}
-
-function pickResolvedLanguage(
-  ...values: Array<RequestLang | undefined>
-): Exclude<RequestLang, "auto"> | undefined {
-  for (const value of values) {
-    if (isResolvedLanguage(value)) {
-      return value;
-    }
-  }
-
-  return undefined;
-}
-
 function buildDetectText(
  title: unknown,
  localizedTitle: unknown,
@ -156,10 +83,7 @@ function resolveHostDetectedLanguage(host: string): RequestLang | undefined {

  if (host === "vk") {
    const trackLang = document.getElementsByTagName("track")?.[0]?.srclang;
-    const normalizedTrackLang = normalizeToRequestLang(trackLang);
-    if (isResolvedLanguage(normalizedTrackLang)) {
-      return normalizedTrackLang;
-    }
+    return normalizeToRequestLang(trackLang);
  }

  return undefined;
@ -180,57 +104,6 @@ function getAriaValueNowPercent(selector: string): number | null {
  return clampPercentInt(now);
 }

-function extractYouTubeVideoId(url: URL): string | undefined {
-  if (url.pathname === "/attribution_link") {
-    const encoded = url.searchParams.get("u");
-    if (encoded) {
-      try {
-        const decoded = decodeURIComponent(encoded);
-        const nestedUrl = decoded.startsWith("http")
-          ? new URL(decoded)
-          : new URL(decoded, url.origin);
-        return extractYouTubeVideoId(nestedUrl);
-      } catch {
-        // ignore malformed nested links
-      }
-    }
-  }
-
-  if (url.hostname === "youtu.be") {
-    const id = url.pathname.replace(/^\/+/, "").split("/")[0];
-    return id || undefined;
-  }
-
-  const vParam = url.searchParams.get("v");
-  if (vParam) {
-    return vParam;
-  }
-
-  return (
-    /\/(?:shorts|embed|live|v|e)\/([^/?#]+)/.exec(url.pathname)?.[1] ??
-    undefined
-  );
-}
-
-function selectDetectTextSource(
-  current: RuntimeVideoData | undefined,
-  fallback: DetectSourceVideoData,
-) {
-  if (current && current.videoId === fallback.videoId) {
-    return {
-      title: current.title,
-      localizedTitle: current.localizedTitle,
-      description: current.description,
-    };
-  }
-
-  return {
-    title: fallback.title,
-    localizedTitle: fallback.localizedTitle,
-    description: fallback.description,
-  };
-}
-
 export class VOTVideoManager {
  videoHandler: VideoHandler;
  private readonly detectInFlightByVideoId = new Map<
@ -254,7 +127,7 @@ export class VOTVideoManager {
    const task: Promise<ResolvedRequestLang | undefined> = (async () => {
      debug.log(`Detecting language text: ${text}`);
      const language = normalizeToRequestLang(await detect(text));
-      return pickResolvedLanguage(language);
+      return isResolvedLanguage(language) ? language : undefined;
    })();

    this.detectInFlightByVideoId.set(videoId, task);
@ -267,139 +140,54 @@ export class VOTVideoManager {
    }
  }

-  private scheduleLanguageDetection(videoData: DetectSourceVideoData): void {
-    if (videoData.detectedLanguage !== "auto") {
-      return;
-    }
-
-    const source = selectDetectTextSource(
-      this.videoHandler.videoData,
-      videoData,
-    );
-    const text = buildDetectText(
-      source.title,
-      source.localizedTitle,
-      source.description,
-    );
-    if (!text) {
-      return;
-    }
-
-    void this.detectLanguageSingleFlight(videoData.videoId, text)
-      .then((detectedLanguage) => {
-        if (!detectedLanguage) {
-          return;
-        }
-        const latestVideoData = this.videoHandler.videoData;
-        if (!latestVideoData || latestVideoData.videoId !== videoData.videoId) {
-          return;
-        }
-        if (latestVideoData.detectedLanguage !== "auto") {
-          return;
-        }
-
-        this.setSelectMenuValues(
-          detectedLanguage,
-          latestVideoData.responseLanguage,
-        );
-        debug.log(
-          `[VOT] Async detected language resolved: ${detectedLanguage} for video ${videoData.videoId}`,
-        );
-      })
-      .catch((error) => {
-        debug.log("[VOT] Async detect failed", error);
-      });
-  }
-
-  private getYouTubeVideoDataFast(): RawVideoData {
-    const playerData = YoutubeHelper.getPlayerData();
-    const playerResponse = YoutubeHelper.getPlayerResponse();
-    const videoId =
-      pickFirstNonEmptyString(playerData?.video_id) ??
-      extractYouTubeVideoId(new URL(globalThis.location.href));
-
-    if (!videoId) {
-      throw new Error("[VOT] Failed to resolve YouTube videoId");
-    }
-
-    const { title: localizedTitle } = playerData ?? {};
-    const {
-      shortDescription: description,
-      isLive: isStream,
-      title,
-    } = playerResponse?.videoDetails ?? {};
-
-    const subtitles = YoutubeHelper.getSubtitles(localizationProvider.lang);
-    const duration = YoutubeHelper.getPlayer()?.getDuration?.() ?? undefined;
-    const detectedLanguage = normalizeToRequestLang(
-      YoutubeHelper.getLanguage(),
-    );
-
-    return {
-      duration,
-      url: `${this.videoHandler.site.url}${videoId}`,
-      videoId,
-      host: this.videoHandler.site.host,
-      title,
-      localizedTitle,
-      description,
-      detectedLanguage,
-      subtitles,
-      isStream: Boolean(isStream),
-    };
-  }
-
  async getVideoData() {
-    let rawVideoData: RawVideoData;
-    if (this.videoHandler.site.host === "youtube") {
-      rawVideoData = this.getYouTubeVideoDataFast();
-    } else {
-      rawVideoData = await getVideoData(this.videoHandler.site, {
-        fetchFn: GM_fetch,
-        video: this.videoHandler.video,
-        language: localizationProvider.lang,
-      });
-    }
-
    const {
      duration,
      url,
      videoId,
      host,
      title,
-      translationHelp,
+      translationHelp = null,
      localizedTitle,
      description,
      detectedLanguage: possibleLanguage,
      subtitles,
      isStream = false,
-    } = rawVideoData;
+    } = await getVideoData(this.videoHandler.site, {
+      fetchFn: GM_fetch,
+      video: this.videoHandler.video,
+      language: localizationProvider.lang,
+    });

-    const possibleRequestLanguage = normalizeToRequestLang(possibleLanguage);
-    const selectedRequestLanguage = normalizeToRequestLang(
-      this.videoHandler.translateFromLang,
+    const normalizedPossibleLanguage = normalizeToRequestLang(possibleLanguage);
+    // Do not reuse previous video's language when current metadata has no lang.
+    // This keeps UI/auto behavior consistent on hosts where language is unknown.
+    let detectedLanguage: RequestLang = normalizedPossibleLanguage ?? "auto";
+
+    if (!normalizedPossibleLanguage) {
+      const text = buildDetectText(title, localizedTitle, description);
+      if (text) {
+        try {
+          const language = await this.detectLanguageSingleFlight(videoId, text);
+          if (language) {
+            detectedLanguage = language;
+          }
+        } catch (error) {
+          // Detection is best-effort; metadata loading must keep working.
+          debug.log("[VOT] detectLanguageSingleFlight failed", error);
+        }
+      }
+    }
+
+    const hostDetectedLanguage = resolveHostDetectedLanguage(
+      this.videoHandler.site.host,
    );
-    const shouldUseLanguageFallbacks =
-      this.videoHandler.site.host !== "youtube" ||
-      isResolvedLanguage(possibleRequestLanguage);
-
-    let detectedLanguage = pickResolvedLanguage(
-      possibleRequestLanguage,
-      shouldUseLanguageFallbacks ? selectedRequestLanguage : undefined,
-      shouldUseLanguageFallbacks
-        ? inferLanguageFromSubtitles(subtitles)
-        : undefined,
-    );
-
-    detectedLanguage = pickResolvedLanguage(
-      resolveHostDetectedLanguage(this.videoHandler.site.host),
-      detectedLanguage,
-    );
-
-    const normalizedDetectedLanguage: RequestLang = detectedLanguage ?? "auto";
+    if (hostDetectedLanguage) {
+      detectedLanguage = hostDetectedLanguage;
+    }

    const videoData = {
-      translationHelp: translationHelp ?? null,
+      translationHelp,
      isStream,
      duration:
        duration ||
@ -408,7 +196,7 @@ export class VOTVideoManager {
      videoId,
      url,
      host,
-      detectedLanguage: normalizedDetectedLanguage,
+      detectedLanguage,
      responseLanguage: this.videoHandler.translateToLang,
      subtitles,
      title,
@ -416,18 +204,19 @@ export class VOTVideoManager {
      description,
      downloadTitle: localizedTitle ?? title ?? videoId,
    } satisfies RuntimeVideoData;
-    console.log("[VOT] Detected language:", normalizedDetectedLanguage);

-    this.scheduleLanguageDetection(videoData);
+    console.log("[VOT] Detected language:", detectedLanguage);
    return videoData;
  }

-  videoValidator() {
-    if (!this.videoHandler.videoData || !this.videoHandler.data) {
+  async videoValidator() {
+    const videoData = this.videoHandler.videoData;
+    const data = this.videoHandler.data;
+    if (!videoData || !data) {
      throw new VOTLocalizedError("VOTNoVideoIDFound");
    }

-    console.log("[VOT] Video Data: ", this.videoHandler.videoData);
+    debug.log("VideoValidator videoData: ", this.videoHandler.videoData);
    if (
      this.videoHandler.data.enabledDontTranslateLanguages &&
      this.videoHandler.data.dontTranslateLanguages?.includes(
@ -436,16 +225,13 @@ export class VOTVideoManager {
    ) {
      throw new VOTLocalizedError("VOTDisableFromYourLang");
    }
+
    if (this.videoHandler.videoData.isStream) {
-      // Stream translation (HLS) is currently disabled.
-      // to translate streams on twitch, need to somehow go back 30(?) seconds to the player
+      // Stream translation is disabled for all hosts.
      throw new VOTLocalizedError("VOTStreamNotAvailable");
    }

-    if (
-      // !this.videoHandler.videoData.isStream &&
-      this.videoHandler.videoData.duration > 14400
-    ) {
+    if (this.videoHandler.videoData.duration > 14400) {
      throw new VOTLocalizedError("VOTVideoIsTooLong");
    }
    return true;
@ -535,26 +321,28 @@ export class VOTVideoManager {
  }

  setSelectMenuValues(from: RequestLang, to: ResponseLang) {
-    if (
-      !this.videoHandler.uiManager.votOverlayView?.isInitialized() ||
-      !this.videoHandler.videoData
-    ) {
+    const videoData = this.videoHandler.videoData;
+    if (!videoData) {
      return this;
    }

    const normalizedFrom = normalizeToRequestLang(from) ?? "auto";
    console.log(`[VOT] Set translation from ${normalizedFrom} to ${to}`);
-    this.videoHandler.uiManager.votOverlayView.languagePairSelect.fromSelect.selectTitle =
+    videoData.detectedLanguage = normalizedFrom;
+    videoData.responseLanguage = to;
+    this.videoHandler.translateFromLang = normalizedFrom;
+    this.videoHandler.translateToLang = to;
+
+    const overlayView = this.videoHandler.uiManager.votOverlayView;
+    if (!overlayView?.isInitialized()) {
+      return this;
+    }
+
+    overlayView.languagePairSelect.fromSelect.selectTitle =
      localizationProvider.getLangLabel(normalizedFrom);
-    this.videoHandler.uiManager.votOverlayView.languagePairSelect.toSelect.selectTitle =
+    overlayView.languagePairSelect.toSelect.selectTitle =
      localizationProvider.getLangLabel(to);
-    this.videoHandler.uiManager.votOverlayView.languagePairSelect.fromSelect.setSelectedValue(
-      normalizedFrom,
-    );
-    this.videoHandler.uiManager.votOverlayView.languagePairSelect.toSelect.setSelectedValue(
-      to,
-    );
-    this.videoHandler.videoData.detectedLanguage = normalizedFrom;
-    this.videoHandler.videoData.responseLanguage = to;
+    overlayView.languagePairSelect.fromSelect.setSelectedValue(normalizedFrom);
+    overlayView.languagePairSelect.toSelect.setSelectedValue(to);
  }
 }
--- a/src/extension/background.ts
+++ b/src/extension/background.ts
@ -40,7 +40,6 @@ type XhrStartMessage = {
    headers?: Record<string, unknown>;
    data?: unknown;
    responseType?: string;
-    wantProgressEvents?: boolean;
    timeout?: number;
    anonymous?: boolean;
    withCredentials?: boolean;
@ -56,6 +55,7 @@ type XhrStartMessage = {
 type XhrAbortMessage = { type: "abort" };

 type XhrPortMessage = XhrStartMessage | XhrAbortMessage;
+const MAX_INLINE_BINARY_RESPONSE_BYTES = 512 * 1024;

 // -----------------------------
 // declarativeNetRequest helper
@ -161,15 +161,9 @@ async function ensureDnrHeaderRuleForYandex(
  // ---------------------------------------------------------------------
  // Header injection / normalization
  //
-  // The user-provided "Правильный запрос" capture for
  // `https://api.browser.yandex.ru/video-translation/translate` does NOT include
  // an `Origin` header.
  //
-  // In a previous build we set Origin to the current page origin (e.g.
-  // https://www.youtube.com) to avoid leaking `chrome-extension://<id>`. That
-  // still diverges from the native Yandex request, so we now remove `Origin`
-  // entirely.
-  //
  // In MV3, fetch()/XHR cannot control forbidden headers like `Origin` or
  // `Sec-*`. We use declarativeNetRequest.modifyHeaders (session rules) to:
  //   - remove Origin completely,
@ -292,32 +286,13 @@ type XhrResponse = {
  // without having to ship non-JSON types through extension messaging.
  responseType?: string;
  contentType?: string;
-  // Optional fallback for small binary payloads when chunked progress events
-  // are unavailable or dropped.
+  // Optional fallback for binary payloads in terminal messages.
  responseB64?: string;
  response?: unknown;
  responseText?: string;
  error?: string;
 };

-type XhrProgress = {
-  finalUrl: string;
-  readyState: number;
-  status: number;
-  statusText: string;
-  responseHeaders: string;
-  loaded: number;
-  total: number;
-  lengthComputable: boolean;
-  // JSON-serializable binary chunk.
-  // The bridge (content script) decodes this to ArrayBuffer before forwarding
-  // it to the MAIN-world GM_xmlhttpRequest callbacks.
-  chunkB64?: string;
-};
-
-// Base64 helpers live in `base64.ts`.
-const MAX_INLINE_BINARY_RESPONSE_BYTES = 512 * 1024;
-
 function getHeader(
  headers: Record<string, string>,
  name: string,
@ -444,14 +419,6 @@ ext?.runtime?.onConnect?.addListener?.((port: unknown) => {
    }
    const timeout = Number(details.timeout || 0);
    const responseType = String(details.responseType || "text").toLowerCase();
-    const wantProgressEvents = !!details.wantProgressEvents;
-    let hostname = "";
-    try {
-      hostname = new URL(url).hostname;
-    } catch {
-      hostname = "";
-    }
-    const isYandexApiRequest = isYandexApiHostname(hostname);
    debug.log("[VOT EXT][background][xhr] start", {
      xhrSessionId,
      state: "in_flight",
@ -459,7 +426,6 @@ ext?.runtime?.onConnect?.addListener?.((port: unknown) => {
      method,
      responseType,
      timeoutMs: timeout,
-      wantProgressEvents,
      headerCount: Object.keys(allHeaders).length,
      headerNames: Object.keys(allHeaders),
      forbiddenHeaderNames: Object.keys(forbiddenHeaders),
@ -662,6 +628,7 @@ ext?.runtime?.onConnect?.addListener?.((port: unknown) => {

      const responseHeaders = formatHeaders(res.headers);
      const finalUrl = res.url || url;
+      const responseContentType = res.headers.get("content-type") || "";

      const makeBase = (
        readyState: number,
@ -685,90 +652,46 @@ ext?.runtime?.onConnect?.addListener?.((port: unknown) => {
      let responseText: string | undefined;
      let responseB64: string | undefined;

-      // For Yandex protobuf calls we don't need progress events in GM_fetch.
-      // Sending only a terminal payload reduces extension message overhead.
-      const shouldStreamBinary =
-        wantBinary && !!res.body && (wantProgressEvents || !isYandexApiRequest);
+      if (wantBinary) {
+        const contentLength = Number(res.headers.get("content-length") || 0);
+        const shouldStreamBinary =
+          !!res.body &&
+          (!Number.isFinite(contentLength) ||
+            contentLength > MAX_INLINE_BINARY_RESPONSE_BYTES);

-      if (shouldStreamBinary) {
-        const total = Number(res.headers.get("content-length") || 0) || 0;
-        let loaded = 0;
-        const reader = res.body.getReader();
-        const inlineChunks: Uint8Array[] = [];
-        let inlineBytes = 0;
-        let canInline = true;
+        if (shouldStreamBinary) {
+          // Large binaries are streamed as progress chunks to avoid one huge
+          // base64 payload in extension messaging.
+          let loaded = 0;
+          const total = Number.isFinite(contentLength) ? contentLength : 0;
+          const reader = res.body.getReader();
+          while (true) {
+            const { done, value } = await reader.read();
+            if (done) break;
+            if (!value) continue;

-        while (true) {
-          const { done, value } = await reader.read();
-          if (done) break;
-          if (!value) continue;
-
-          loaded += value.byteLength;
-
-          if (canInline) {
-            const nextInlineBytes = inlineBytes + value.byteLength;
-            if (nextInlineBytes <= MAX_INLINE_BINARY_RESPONSE_BYTES) {
-              inlineChunks.push(value.slice());
-              inlineBytes = nextInlineBytes;
-            } else {
-              canInline = false;
-              inlineChunks.length = 0;
-              inlineBytes = 0;
-            }
-          }
-
-          const progress: XhrProgress = {
-            ...makeBase(3),
-            loaded,
-            total,
-            lengthComputable: total > 0,
-            chunkB64: bytesToBase64(value),
-          };
-
-          try {
+            loaded += value.byteLength;
            safePostMessage({
              type: "progress",
              state: "in_flight",
-              progress,
+              progress: {
+                ...makeBase(3),
+                loaded,
+                total,
+                lengthComputable: total > 0,
+                chunkB64: bytesToBase64(value),
+              },
            });
-            debug.log("[VOT EXT][background][xhr] progress", {
-              xhrSessionId,
-              url: finalUrl,
-              loaded,
-              total,
-            });
-          } catch {
-            // ignore
          }
-        }
-
-        if (inlineChunks.length && inlineBytes > 0) {
-          const merged = new Uint8Array(inlineBytes);
-          let offset = 0;
-          for (const chunk of inlineChunks) {
-            merged.set(chunk, offset);
-            offset += chunk.byteLength;
-          }
-          responseB64 = bytesToBase64(merged);
-        }
-
-        // Binary bodies are streamed to the bridge via progress events.
-        // We intentionally avoid sending the full binary payload in the final
-        // "load" message because extension messaging only supports
-        // JSON-serializable objects.
-        response = undefined;
-      } else if (wantBinary) {
-        // e.g. Yandex protobuf requests without onprogress handlers (or HEAD).
-        // We return a single terminal payload instead of progress chunks.
-        try {
+          response = undefined;
+        } else {
+          // Small binaries can be delivered in one terminal payload.
          const ab = await res.arrayBuffer();
          if (ab.byteLength > 0) {
            responseB64 = arrayBufferToBase64(ab);
          }
-        } catch {
-          // ignore
+          response = undefined;
        }
-        response = undefined;
      } else if (responseType === "json") {
        responseText = await res.text();
        try {
@ -793,7 +716,6 @@ ext?.runtime?.onConnect?.addListener?.((port: unknown) => {
        responseTextLength: responseText?.length ?? 0,
        responseB64Length: responseB64?.length ?? 0,
      });
-      const responseContentType = res.headers.get("content-type") || "";
      safePostMessage({
        type: "load",
        state: "terminal",
--- a/src/extension/prelude.ts
+++ b/src/extension/prelude.ts
@ -179,7 +179,6 @@ function toSerializableXhrDetails(details: AnyObject): AnyObject {
    responseType: details.responseType,
    anonymous: details.anonymous,
    withCredentials: details.withCredentials,
-    wantProgressEvents: typeof details.onprogress === "function",
  };
 }

@ -215,9 +214,6 @@ async function toBridgeXhrDetails(details: AnyObject): Promise<AnyObject> {
    responseType: details.responseType,
    anonymous: details.anonymous,
    withCredentials: details.withCredentials,
-    // Progress is expensive in extension messaging for tiny protobuf responses.
-    // Keep it only when caller actually subscribed to onprogress.
-    wantProgressEvents: typeof details.onprogress === "function",
  };
 }

--- a/src/headers.json
+++ b/src/headers.json
@ -1,7 +1,7 @@
 {
  "name": "[VOT] - Voice Over Translation",
  "description": "A small extension that adds a Yandex Browser video translation to other browsers",
-  "version": "1.11.0",
+  "version": "1.11.1",
  "author": "Toil, SashaXser, MrSoczekXD, mynovelhost, sodapng",
  "namespace": "vot",
  "icon": "https://translate.yandex.ru/icons/favicon.ico",
--- a/src/index.ts
+++ b/src/index.ts
@ -48,11 +48,15 @@ import {
 import { VideoObserver } from "./utils/VideoObserver";
 import VOTLocalizedError from "./utils/VOTLocalizedError";
 import {
-  clampInt,
  clampPercentInt,
  snapVolume01,
  volume01ToPercent,
 } from "./utils/volume";
+import {
+  applyVolumeLinkDelta,
+  syncTranslationLinkSnapshot,
+  syncVideoLinkSnapshot,
+} from "./utils/volumeLink";
 import {
  getAutoHideDelay as getAutoHideDelayImpl,
  initExtraEvents as initExtraEventsImpl,
@ -163,6 +167,12 @@ export class VideoHandler {
  internalVideoVolumeSetAt = 0;
  internalVideoVolumeSetPercent: number | null = null;
  internalVideoVolumeSuppressionMs = 250;
+  internalVideoVolumeSetHistory: Array<{
+    at: number;
+    percent: number;
+    suppressMs: number;
+  }> = [];
+  internalVideoVolumeSetHistoryLimit = 48;

  // Smart auto-volume ducking state. Used to lower the original video volume
  // only while the translated track has audible sound (not during silence).
@ -196,6 +206,11 @@ export class VideoHandler {
  subtitlesWidget?: SubtitlesWidget;

  activeTranslation: { key: string; promise: Promise<unknown> } | null = null;
+  /**
+   * In-flight async teardown for translation/audio player cleanup.
+   * New translation starts should wait for this to avoid clear/init races.
+   */
+  stopTranslatePromise: Promise<void> | null = null;

  // Managers
  interactionChecker!: IntervalIdleChecker;
@ -614,13 +629,8 @@ export class VideoHandler {
   * Run auto translate using orchestrator dependencies.
   */
  async runAutoTranslate() {
-    try {
-      this.videoManager.videoValidator();
-      await this.uiManager.handleTranslationBtnClick();
-    } catch (err) {
-      console.error("[VOT]", err);
-      throw err;
-    }
+    await this.videoManager.videoValidator();
+    await this.uiManager.handleTranslationBtnClick();
  }

  /**
@ -686,12 +696,27 @@ export class VideoHandler {
   * our own recent programmatic setVideoVolume call.
   */
  isLikelyInternalVideoVolumeChange(observedPercent: number) {
+    const now = Date.now();
+    if (this.internalVideoVolumeSetHistory.length > 0) {
+      this.internalVideoVolumeSetHistory =
+        this.internalVideoVolumeSetHistory.filter(
+          (entry) => now - entry.at <= entry.suppressMs,
+        );
+
+      for (const entry of this.internalVideoVolumeSetHistory) {
+        // Allow a 1% tolerance to account for hosts that quantize volume.
+        if (Math.abs(observedPercent - entry.percent) <= 1) {
+          return true;
+        }
+      }
+      return false;
+    }
+
    if (this.internalVideoVolumeSetPercent === null) return false;

-    const ageMs = Date.now() - this.internalVideoVolumeSetAt;
+    const ageMs = now - this.internalVideoVolumeSetAt;
    if (ageMs > this.internalVideoVolumeSuppressionMs) return false;

-    // Allow a 1% tolerance to account for hosts that quantize volume.
    return Math.abs(observedPercent - this.internalVideoVolumeSetPercent) <= 1;
  }

@ -882,14 +907,39 @@ export class VideoHandler {
   * @param {number} volume A number between 0 and 1.
   * @returns {VideoHandler} This instance.
   */
-  setVideoVolume(volume: number): this {
+  setVideoVolume(
+    volume: number,
+    options: { suppressSyncMs?: number } = {},
+  ): this {
    const snapped = snapVolume01(volume);
+    const suppressSyncMs =
+      typeof options.suppressSyncMs === "number" &&
+      Number.isFinite(options.suppressSyncMs)
+        ? Math.max(0, options.suppressSyncMs)
+        : this.internalVideoVolumeSuppressionMs;
+    const now = Date.now();
+    const percent = volume01ToPercent(snapped);

    // Remember this programmatic update so external observers (e.g. YouTube aria
    // mutations) won't treat it as a user-driven volume change and resync volumes
    // again (which would cause drift/loops).
-    this.internalVideoVolumeSetAt = Date.now();
-    this.internalVideoVolumeSetPercent = volume01ToPercent(snapped);
+    this.internalVideoVolumeSetAt = now;
+    this.internalVideoVolumeSetPercent = percent;
+    this.internalVideoVolumeSetHistory.push({
+      at: now,
+      percent,
+      suppressMs: suppressSyncMs,
+    });
+    if (
+      this.internalVideoVolumeSetHistory.length >
+      this.internalVideoVolumeSetHistoryLimit
+    ) {
+      this.internalVideoVolumeSetHistory.splice(
+        0,
+        this.internalVideoVolumeSetHistory.length -
+          this.internalVideoVolumeSetHistoryLimit,
+      );
+    }

    this.videoManager.setVideoVolume(snapped);
    return this;
@ -904,7 +954,7 @@ export class VideoHandler {
    // If syncVolume isn't initialized yet, keep the state aligned so the first
    // delta computation won't jump.
    if (!this.volumeLinkState.initialized) {
-      this.volumeLinkState.lastVideoPercent = normalized;
+      syncVideoLinkSnapshot(this.volumeLinkState, normalized);
      return;
    }

@ -919,7 +969,30 @@ export class VideoHandler {
      return;
    }

-    this.volumeLinkState.lastVideoPercent = normalized;
+    syncVideoLinkSnapshot(this.volumeLinkState, normalized);
+  }
+
+  /**
+   * Keeps internal translation-volume snapshot aligned when syncVolume is
+   * temporarily disabled, so re-enabling link mode does not apply stale deltas.
+   */
+  onTranslationVolumeSliderSynced(volumePercent: number) {
+    if (!this.volumeLinkState.initialized) {
+      syncTranslationLinkSnapshot(this.volumeLinkState, volumePercent);
+      return;
+    }
+
+    syncTranslationLinkSnapshot(this.volumeLinkState, volumePercent);
+  }
+
+  /**
+   * Re-seeds syncVolume baseline from current UI slider values.
+   * Useful when toggling syncVolume on/off to avoid stale delta state.
+   */
+  resetVolumeLinkState(videoPercent: number, translationPercent: number): void {
+    syncVideoLinkSnapshot(this.volumeLinkState, videoPercent);
+    syncTranslationLinkSnapshot(this.volumeLinkState, translationPercent);
+    this.volumeLinkState.initialized = true;
  }

  /**
@ -972,61 +1045,28 @@ export class VideoHandler {
    if (!videoSlider || !translationSlider) {
      return;
    }
+    const { nextVideo, nextTranslation } = applyVolumeLinkDelta({
+      state: this.volumeLinkState,
+      fromType,
+      newVolume,
+      currentVideo: Number(videoSlider.value),
+      currentTranslation: Number(translationSlider.value),
+      translationMin: translationSlider.min,
+      translationMax: translationSlider.max,
+    });

-    // Initialize state once from current slider values.
-    if (!this.volumeLinkState.initialized) {
-      this.volumeLinkState.lastVideoPercent = Number(videoSlider.value);
-      this.volumeLinkState.lastTranslationPercent = Number(
-        translationSlider.value,
-      );
-      this.volumeLinkState.initialized = true;
-    }
-
-    if (fromType === "video") {
-      const prevVideo = this.volumeLinkState.lastVideoPercent;
-      const delta = newVolume - prevVideo;
-
-      // Always update the initiator snapshot, even if delta is 0 / invalid.
-      this.volumeLinkState.lastVideoPercent = newVolume;
-
-      if (!Number.isFinite(delta) || delta === 0) {
-        return;
-      }
-
-      const currentTranslation = Number(translationSlider.value);
-      const nextTranslation = clampInt(
-        currentTranslation + delta,
-        translationSlider.min,
-        translationSlider.max,
-      );
-
+    if (typeof nextTranslation === "number") {
      translationSlider.value = nextTranslation;
-      this.volumeLinkState.lastTranslationPercent = nextTranslation;
-
      if (this.audioPlayer?.player) {
        this.audioPlayer.player.volume = nextTranslation / 100;
      }
-
      return;
    }

-    // fromType === "translation"
-    const prevTranslation = this.volumeLinkState.lastTranslationPercent;
-    const delta = newVolume - prevTranslation;
-
-    this.volumeLinkState.lastTranslationPercent = newVolume;
-
-    if (!Number.isFinite(delta) || delta === 0) {
-      return;
+    if (typeof nextVideo === "number") {
+      videoSlider.value = nextVideo;
+      this.setVideoVolume(nextVideo / 100);
    }
-
-    const currentVideo = Number(videoSlider.value);
-    const nextVideo = clampPercentInt(currentVideo + delta);
-
-    videoSlider.value = nextVideo;
-    this.volumeLinkState.lastVideoPercent = nextVideo;
-
-    this.setVideoVolume(nextVideo / 100);
  }

  /**
@ -1039,64 +1079,83 @@ export class VideoHandler {

  /**
   * Validates the video.
-   * @returns {boolean} True if valid.
+   * @returns {Promise<boolean>} True if valid.
   */
-  videoValidator() {
-    return this.videoManager.videoValidator();
+  async videoValidator() {
+    return await this.videoManager.videoValidator();
  }

  /**
   * Stops translation and resets UI elements.
   */
-  stopTranslate() {
-    if (this.audioPlayer?.player) {
-      try {
-        this.audioPlayer.player.removeVideoEvents();
-        this.audioPlayer.player.clear();
-        this.audioPlayer.player.src = "";
-      } catch (err) {
-        debug.log("[stopTranslate] audioPlayer cleanup error", err);
-      }
-      debug.log("audioPlayer after stopTranslate", this.audioPlayer);
+  stopTranslate(): Promise<void> {
+    if (this.stopTranslatePromise) {
+      return this.stopTranslatePromise;
    }
-    this.activeTranslation = null;
-    const overlayView = this.uiManager.votOverlayView;
-    if (overlayView) {
-      if (overlayView.videoVolumeSlider) {
-        overlayView.videoVolumeSlider.hidden = true;
-      }
-      if (overlayView.translationVolumeSlider) {
-        overlayView.translationVolumeSlider.hidden = true;
-      }
-      if (overlayView.downloadTranslationButton) {
-        overlayView.downloadTranslationButton.hidden = true;
-      }
-    }
-    this.downloadTranslationUrl = null;
-    this.longWaitingResCount = 0;
-    this.hadAsyncWait = false;
-    this.transformBtn("none", localizationProvider.get("translateVideo"));
-    debug.log(`Volume on start: ${this.volumeOnStart}`);

-    // Restore the original video volume. If the user adjusted volume while
-    // ducking was enabled, prefer the latest baseline volume.
-    const restoreVolume =
-      typeof this.smartVolumeDuckingBaseline === "number"
-        ? this.smartVolumeDuckingBaseline
-        : this.volumeOnStart;
+    const cleanup = async () => {
+      if (this.audioPlayer?.player) {
+        try {
+          this.audioPlayer.player.removeVideoEvents();
+          this.audioPlayer.player.src = "";
+          await this.audioPlayer.player.clear();
+        } catch (err) {
+          debug.log("[stopTranslate] audioPlayer cleanup error", err);
+        }
+        debug.log("audioPlayer after stopTranslate", this.audioPlayer);
+      }
+      this.activeTranslation = null;
+      const overlayView = this.uiManager.votOverlayView;
+      if (overlayView) {
+        if (overlayView.videoVolumeSlider) {
+          overlayView.videoVolumeSlider.hidden = true;
+        }
+        if (overlayView.translationVolumeSlider) {
+          overlayView.translationVolumeSlider.hidden = true;
+        }
+        if (overlayView.downloadTranslationButton) {
+          overlayView.downloadTranslationButton.hidden = true;
+        }
+      }
+      this.downloadTranslationUrl = null;
+      this.longWaitingResCount = 0;
+      this.hadAsyncWait = false;
+      this.transformBtn("none", localizationProvider.get("translateVideo"));
+      debug.log(`Volume on start: ${this.volumeOnStart}`);

-    stopSmartVolumeDuckingImpl(this, { restoreVolume });
-    this.volumeOnStart = undefined;
-    if (this.autoRetry !== undefined) {
-      clearTimeout(this.autoRetry);
-      this.autoRetry = undefined;
-    }
-    if (this.translationRefreshTimeout !== undefined) {
-      clearTimeout(this.translationRefreshTimeout);
-      this.translationRefreshTimeout = undefined;
-    }
-    // Cancel in-flight translation work.
-    this.resetActionsAbortController("stopTranslate");
+      // Restore the original video volume. If the user adjusted volume while
+      // ducking was enabled, prefer the latest baseline volume.
+      const restoreVolume =
+        typeof this.smartVolumeDuckingBaseline === "number"
+          ? this.smartVolumeDuckingBaseline
+          : this.volumeOnStart;
+
+      stopSmartVolumeDuckingImpl(this, { restoreVolume });
+      this.volumeOnStart = undefined;
+      if (this.autoRetry !== undefined) {
+        clearTimeout(this.autoRetry);
+        this.autoRetry = undefined;
+      }
+      if (this.translationRefreshTimeout !== undefined) {
+        clearTimeout(this.translationRefreshTimeout);
+        this.translationRefreshTimeout = undefined;
+      }
+      // Cancel in-flight translation work.
+      this.resetActionsAbortController("stopTranslate");
+    };
+
+    const inFlight = cleanup().finally(() => {
+      if (this.stopTranslatePromise === inFlight) {
+        this.stopTranslatePromise = null;
+      }
+    });
+
+    this.stopTranslatePromise = inFlight;
+    return inFlight;
+  }
+
+  waitForPendingStopTranslate(): Promise<void> {
+    return this.stopTranslatePromise ?? Promise.resolve();
  }

  /**
@ -1336,10 +1395,10 @@ export class VideoHandler {
  /**
   * Stops translation and synchronizes volume.
   */
-  stopTranslation = () => {
+  stopTranslation = async () => {
    this.translationOrchestrator?.reset();
    this.overlayVisibility?.cancel();
-    this.stopTranslate();
+    await this.stopTranslate();
    this.syncVideoVolumeSlider();
  };

@ -1357,7 +1416,7 @@ export class VideoHandler {
    debug.log("[VideoHandler] release");
    this.initialized = false;
    try {
-      this.stopTranslation();
+      await this.stopTranslation();
    } catch (err) {
      debug.log("[VideoHandler] stopTranslation failed during release", err);
    }
--- a/src/localization/localizationProvider.ts
+++ b/src/localization/localizationProvider.ts
@ -10,6 +10,13 @@ import rawDefaultLocale from "./locales/en.json";

 export type LangOverride = "auto" | Locale;

+const repoBranch =
+  typeof REPO_BRANCH !== "undefined" && REPO_BRANCH ? REPO_BRANCH : "master";
+const availableLocales =
+  typeof AVAILABLE_LOCALES !== "undefined" && Array.isArray(AVAILABLE_LOCALES)
+    ? AVAILABLE_LOCALES
+    : ["en"];
+
 class LocalizationProvider {
  storageKeys: LocaleStorageKey[] = [
    "localePhrases",
@ -29,8 +36,8 @@ class LocalizationProvider {
  defaultLocale: FlatPhrases = toFlatObj(rawDefaultLocale);

  cacheTTL = 7200;
-  localesUrl = `${contentUrl}/${REPO_BRANCH}/src/localization/locales`;
-  hashesUrl = `${contentUrl}/${REPO_BRANCH}/src/localization/hashes.json`;
+  localesUrl = `${contentUrl}/${repoBranch}/src/localization/locales`;
+  hashesUrl = `${contentUrl}/${repoBranch}/src/localization/hashes.json`;

  _langOverride: LangOverride = "auto";

@ -62,9 +69,9 @@ class LocalizationProvider {
    // Older extension builds injected AVAILABLE_LOCALES without the `auto`
    // option. Ensure it is always present so Settings → Language can restore
    // automatic detection.
-    return AVAILABLE_LOCALES.includes("auto")
-      ? AVAILABLE_LOCALES
-      : (["auto", ...AVAILABLE_LOCALES] as LangOverride[]);
+    return availableLocales.includes("auto")
+      ? (availableLocales as LangOverride[])
+      : (["auto", ...availableLocales] as LangOverride[]);
  }

  async reset() {
--- a/src/styles/components/buttons/_mixins.scss
+++ b/src/styles/components/buttons/_mixins.scss
@ -27,7 +27,7 @@
  text-overflow: ellipsis;
  @include shared.vot-font-family;
  font-size: $font-size;
-  font-weight: $font-weight;
+  font-weight: $font-weight !important;
  line-height: $line-height;
  outline: none;
  cursor: pointer;
--- a/src/styles/components/checkbox.scss
+++ b/src/styles/components/checkbox.scss
@ -63,7 +63,7 @@
      padding-left: var(--vot-checkbox-label-offset) !important;
      width: inherit;
      cursor: pointer;
-      font-weight: normal;
+      font-weight: normal !important;

      &::before {
        content: "";
--- a/src/styles/components/dialog.scss
+++ b/src/styles/components/dialog.scss
@ -118,7 +118,7 @@
    display: flex;
    flex: 1;
    font-size: inherit;
-    font-weight: inherit;
+    font-weight: inherit !important;
    margin: 0 !important;
    outline: 0;
  }
@ -126,7 +126,7 @@
  &-title {
    flex: 1;
    font-size: calc(15 / 13 * 100%);
-    font-weight: bold;
+    font-weight: bold !important;
    line-height: 1;
    padding: var(--vot-space-5) var(--vot-space-5) var(--vot-space-4) !important;
  }
--- a/src/styles/components/header.scss
+++ b/src/styles/components/header.scss
@ -7,7 +7,7 @@
    system-ui,
    sans-serif
  );
-  font-weight: bold;
+  font-weight: bold !important;
  line-height: 1.5;
  text-align: start;

--- a/src/styles/components/menu.scss
+++ b/src/styles/components/menu.scss
@ -80,7 +80,7 @@
    display: flex;
    flex: 1;
    font-size: inherit;
-    font-weight: inherit;
+    font-weight: inherit !important;
    margin: 0 !important;
    outline: 0;
    text-align: start;
@ -89,7 +89,7 @@
  &-title {
    flex: 1;
    font-size: 16px;
-    font-weight: 500;
+    font-weight: 500 !important;
    line-height: 1;
    padding: var(--vot-space-4) !important;
  }
--- a/src/styles/components/segmented-button.scss
+++ b/src/styles/components/segmented-button.scss
@ -95,7 +95,7 @@
      margin-left: var(--vot-space-2) !important;
      white-space: nowrap;
      color: inherit;
-      font-weight: 400;
+      font-weight: 400 !important;
    }
  }

--- a/src/styles/components/select.scss
+++ b/src/styles/components/select.scss
@ -17,7 +17,7 @@
    sans-serif
  );
  font-size: 14px;
-  font-weight: normal;
+  font-weight: normal !important;
  line-height: 1.5;
  text-align: start;
  color: var(--vot-helper-theme);
--- a/src/styles/components/slider.scss
+++ b/src/styles/components/slider.scss
@ -41,7 +41,7 @@
    margin-left: 0 !important;
    font-variant-numeric: tabular-nums;
    // Reduce visual noise: values should be legible but not steal attention.
-    font-weight: 500;
+    font-weight: 500 !important;
  }

  .vot-slider-label-text {
--- a/src/styles/components/tooltip.scss
+++ b/src/styles/components/tooltip.scss
@ -1,3 +1,5 @@
+@use "../mixins" as shared;
+
 .vot-tooltip {
  --vot-helper-theme-rgb: var(--vot-onsurface-rgb, 0, 0, 0);
  --vot-helper-theme: rgba(var(--vot-helper-theme-rgb), 0.87);
@ -11,13 +13,7 @@
  color: var(--vot-helper-theme);
  fill: var(--vot-helper-theme);
  border-radius: 4px !important;
-  font-family: var(
-    --vot-font-family,
-    "Roboto",
-    "Segoe UI",
-    system-ui,
-    sans-serif
-  );
+  @include shared.vot-font-family;
  font-size: 14px;
  line-height: 1.5;
  cursor: default;
@ -42,5 +38,6 @@

  & * {
    box-sizing: border-box !important;
+    font-family: inherit !important;
  }
 }
--- a/src/styles/main.scss
+++ b/src/styles/main.scss
@ -100,6 +100,7 @@ vot-block {
    system-ui,
    sans-serif
  ) !important;
+  font-weight: 400 !important;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
@ -110,6 +111,11 @@ vot-block {
  visibility: visible !important;
 }

+// Keep host-page typography rules from overriding VOT font weights.
+vot-block * {
+  font-weight: inherit !important;
+}
+
 // Create an explicit stacking / blending boundary for overlays.
 .vot-portal-local,
 .vot-subtitles-widget {
--- a/src/styles/subtitles.scss
+++ b/src/styles/subtitles.scss
@ -190,6 +190,12 @@
  }
 }

+@media (max-width: 900px) and (pointer: coarse) {
+  .vot-subtitles-widget {
+    --vot-subtitles-fallback-bottom-inset: env(safe-area-inset-bottom, 0px);
+  }
+}
+
 :fullscreen .vot-subtitles,
 :-webkit-full-screen .vot-subtitles {
  // Fullscreen should utilize more horizontal real estate to reduce
--- a/src/subtitles/processor.ts
+++ b/src/subtitles/processor.ts
@ -300,13 +300,19 @@ const ensureProcessedSubtitles = (input: unknown): ProcessedSubtitles => {
  return { subtitles };
 };

+const VK_INLINE_TIMESTAMP_RE = /<(?:\d{1,2}:)?\d{2}:\d{2}(?:[.,]\d{1,3})?>/gu;
+const VK_DUPLICATE_MAX_GAP_MS = 120;
+
 const stripHtmlToText = (value: string): string => {
  if (!value.includes("<")) return value;
-  if (typeof document === "undefined") return value;

-  const template = document.createElement("template");
-  template.innerHTML = value;
-  return template.content.textContent ?? "";
+  if (typeof document !== "undefined") {
+    const template = document.createElement("template");
+    template.innerHTML = value;
+    return template.content.textContent ?? "";
+  }
+
+  return value.replace(/<\/?[^>]+>/gu, "");
 };

 const getYoutubeEventDurationMs = (
@ -616,15 +622,78 @@ export const SubtitlesProcessor = {
  },

  cleanJsonSubtitles(subtitles: ProcessedSubtitles): ProcessedSubtitles {
-    return {
-      subtitles: subtitles.subtitles.map((line) => ({
+    const normalizeText = (value: string): string =>
+      stripHtmlToText(value.replace(VK_INLINE_TIMESTAMP_RE, ""))
+        .replace(/\s+([,.:;!?])/gu, "$1")
+        .replace(/[ \t]*\n[ \t]*/gu, "\n")
+        .replace(/[ \t]{2,}/gu, " ")
+        .replace(/\n{3,}/gu, "\n\n")
+        .trim();
+
+    const normalizeComparable = (value: string): string =>
+      value.toLowerCase().replace(/\s+/gu, " ").trim();
+    const lineEndMs = (line: SubtitleLine): number =>
+      line.startMs + Math.max(0, line.durationMs);
+    const tokensTextLength = (tokens: SubtitleToken[]): number =>
+      tokens.reduce((sum, token) => sum + token.text.length, 0);
+
+    const cleanedLines = subtitles.subtitles
+      .map((line) => ({
        ...line,
-        text: stripHtmlToText(line.text),
-        tokens: line.tokens.map((token) => ({
-          ...token,
-          text: stripHtmlToText(token.text),
-        })),
-      })),
+        text: normalizeText(line.text),
+        tokens: line.tokens
+          .map((token) => ({
+            ...token,
+            text: normalizeText(token.text),
+          }))
+          .filter((token) => token.text.length > 0),
+      }))
+      .filter((line) => line.text.length > 0);
+
+    const mergedLines: SubtitleLine[] = [];
+    for (const line of cleanedLines) {
+      const currentComparable = normalizeComparable(line.text);
+      if (!currentComparable) continue;
+
+      const previous = mergedLines.at(-1);
+      if (!previous) {
+        mergedLines.push(line);
+        continue;
+      }
+
+      const previousComparable = normalizeComparable(previous.text);
+      const previousEnd = lineEndMs(previous);
+      const currentEnd = lineEndMs(line);
+      const isDuplicateText = previousComparable === currentComparable;
+      const isNearPrevious =
+        line.startMs <= previousEnd + VK_DUPLICATE_MAX_GAP_MS;
+
+      if (!isDuplicateText || !isNearPrevious) {
+        mergedLines.push(line);
+        continue;
+      }
+
+      // VK can emit duplicate cue bursts with tiny timing deltas. Merge them
+      // instead of dropping short cues by duration heuristics.
+      const mergedStart = Math.min(previous.startMs, line.startMs);
+      const mergedEnd = Math.max(previousEnd, currentEnd);
+      const previousTokensLength = tokensTextLength(previous.tokens);
+      const currentTokensLength = tokensTextLength(line.tokens);
+      const mergedTokens =
+        currentTokensLength >= previousTokensLength
+          ? line.tokens
+          : previous.tokens;
+
+      mergedLines[mergedLines.length - 1] = {
+        ...previous,
+        startMs: mergedStart,
+        durationMs: Math.max(0, mergedEnd - mergedStart),
+        tokens: mergedTokens,
+      };
+    }
+
+    return {
+      subtitles: mergedLines,
    };
  },

--- a/src/subtitles/widget.ts
+++ b/src/subtitles/widget.ts
@ -535,6 +535,11 @@ export class SubtitlesWidget {
    const h = this.safeAreaProbeEl.offsetHeight || 0;
    return h;
  }
+  private isMobileViewport(): boolean {
+    if (typeof globalThis.matchMedia !== "function") return false;
+    return globalThis.matchMedia("(max-width: 900px) and (pointer: coarse)")
+      .matches;
+  }
  private getBottomInsetPreset() {
    const doc = document as Document & {
      webkitFullscreenElement?: Element | null;
@ -595,6 +600,9 @@ export class SubtitlesWidget {
      Number.parseFloat(
        getComputedStyle(this.container).paddingBottom || "0",
      ) || 0;
+    if (this.isMobileViewport()) {
+      return Math.max(paddingBottom, safeAreaBottom);
+    }
    const anchorH =
      anchorBox?.h ??
      this.computeAnchorBoxLayout(layout ?? this.getLayoutSize()).h;
--- a/src/types/core/eventImpl.ts
+++ b/src/types/core/eventImpl.ts
@ -13,4 +13,4 @@
 */
 export type EventHandler<Args extends unknown[] = unknown[]> = (
  ...args: Args
-) => void;
+) => void | Promise<void>;
--- a/src/types/views/settings.ts
+++ b/src/types/views/settings.ts
@ -18,6 +18,7 @@ export type SettingsViewEventMap = {
  "change:autoSubtitles": [checked: boolean];
  "change:showVideoVolume": [checked: boolean];
  "change:audioBooster": [checked: boolean];
+  "change:syncVolume": [checked: boolean];
  "change:useLivelyVoice": [checked: boolean];
  "change:subtitlesHighlightWords": [checked: boolean];
  "change:subtitlesSmartLayout": [checked: boolean];
--- a/src/ui/manager.ts
+++ b/src/ui/manager.ts
@ -14,7 +14,7 @@ import type { OverlayMount, UIManagerProps } from "../types/uiManager";
 import ui from "../ui";
 import debug from "../utils/debug";
 import { buildTranslationBlob, downloadTranslation } from "../utils/download";
-import { GM_fetch, isSupportGMXhr } from "../utils/gm";
+import { GM_fetch } from "../utils/gm";
 import type { IntervalIdleChecker } from "../utils/intervalIdleChecker";
 import { votStorage } from "../utils/storage";
 import {
@ -22,7 +22,6 @@ import {
  clearFileName,
  downloadBlob,
  exitFullscreen,
-  revokeObjectUrlLater,
 } from "../utils/utils";
 import VOTLocalizedError from "../utils/VOTLocalizedError";
 import VOTButton from "./components/votButton";
@ -178,9 +177,9 @@ export class UIManager {

        const downloadButton = this.votOverlayView.downloadTranslationButton;
        const downloadUrl = this.videoHandler.downloadTranslationUrl;
-        const filename = clearFileName(
-          this.videoHandler.videoData.downloadTitle,
-        );
+        const filename = this.data.downloadWithName
+          ? clearFileName(this.videoHandler.videoData.downloadTitle)
+          : `translation_${this.videoHandler.videoData.videoId}`;
        const isMobile = this.videoHandler.site.additionalData === "mobile";

        if (downloadButton) {
@ -204,35 +203,10 @@ export class UIManager {
                }
              },
            );
-            const file = new File([blob], `${filename}.mp3`, {
-              type: blob.type || "audio/mpeg",
-            });
-            const canShareFiles =
-              typeof navigator !== "undefined" &&
-              typeof navigator.canShare === "function" &&
-              navigator.canShare({ files: [file] });
-            if (navigator?.share && canShareFiles) {
-              await navigator.share({ files: [file], title: filename });
-              return;
-            }
-            const fallbackUrl = URL.createObjectURL(blob);
-            globalThis.open(fallbackUrl, "_blank")?.focus();
-            revokeObjectUrlLater(fallbackUrl);
+            await this.saveBlobWithMobileShare(blob, `${filename}.mp3`, true);
            return;
          }

-          if (!this.data.downloadWithName || !isSupportGMXhr) {
-            globalThis.open(downloadUrl, "_blank")?.focus();
-            return;
-          }
-
-          if (!downloadButton) {
-            throw new Error(
-              "[VOT] Download translation button is not initialized",
-            );
-          }
-
-          downloadButton.progress = 0;
          // Download the full audio. A range request (bytes=0-0) only returns a
          // tiny fragment (~1 byte + headers) which results in a silent ~5KB file.
          const res = await GM_fetch(downloadUrl, { timeout: 0 });
@ -240,11 +214,15 @@ export class UIManager {
            throw new Error(`HTTP ${res.status}`);
          }
          await downloadTranslation(res, filename, (progress) => {
-            downloadButton.progress = progress;
+            if (downloadButton) {
+              downloadButton.progress = progress;
+            }
          });
        } catch (err) {
          console.error("[VOT] Download translation failed:", err);
-          globalThis.open(downloadUrl, "_blank")?.focus();
+          if (!this.triggerUrlDownload(downloadUrl, `${filename}.mp3`)) {
+            globalThis.open(downloadUrl, "_blank")?.focus();
+          }
        } finally {
          if (downloadButton) {
            downloadButton.progress = 0;
@ -284,6 +262,7 @@ export class UIManager {

        this.videoHandler.setVideoVolume(volume / 100);
        if (!this.data.syncVolume) {
+          this.videoHandler.onVideoVolumeSliderSynced(volume);
          return;
        }

@ -299,6 +278,7 @@ export class UIManager {
        const nextVolume = volume ?? this.data.defaultVolume ?? 100;
        this.videoHandler.audioPlayer.player.volume = nextVolume / 100;
        if (!this.data.syncVolume) {
+          this.videoHandler.onTranslationVolumeSliderSynced(nextVolume);
          return;
        }
        this.videoHandler.syncVolumeWrapper("translation", nextVolume);
@ -354,15 +334,35 @@ export class UIManager {
          const currentVolume = overlayView.translationVolumeSlider.value;
          const maxVolume = this.data.audioBooster ? maxAudioVolume : 100;
          overlayView.translationVolumeSlider.max = maxVolume;
-          overlayView.translationVolumeSlider.value = clamp(
-            currentVolume,
-            0,
-            maxVolume,
+          const nextVolume = clamp(currentVolume, 0, maxVolume);
+          overlayView.translationVolumeSlider.value = nextVolume;
+          this.videoHandler?.onTranslationVolumeSliderSynced(nextVolume);
+        });
+      })
+      .addEventListener("change:syncVolume", (checked) => {
+        if (!this.videoHandler) {
+          return;
+        }
+        this.videoHandler.setupAudioSettings();
+        if (!checked) {
+          return;
+        }
+
+        this.withInitializedOverlayView((overlayView) => {
+          const videoSlider = overlayView.videoVolumeSlider;
+          const translationSlider = overlayView.translationVolumeSlider;
+          if (!videoSlider || !translationSlider) {
+            return;
+          }
+
+          this.videoHandler.resetVolumeLinkState(
+            Number(videoSlider.value),
+            Number(translationSlider.value),
          );
        });
      })
      .addEventListener("change:useLivelyVoice", () => {
-        this.videoHandler?.stopTranslate();
+        void this.videoHandler?.stopTranslate();
      })
      .addEventListener("change:subtitlesHighlightWords", (checked) => {
        this.withSubtitlesWidget((widget) => {
@ -394,14 +394,13 @@ export class UIManager {
          return;
        }

-        // Proxy host changes can invalidate cached requests/URLs.
-        // Best-effort refresh the active audio source and clear caches.
+        // Proxy host changes invalidate cached requests/URLs and should stop
+        // the current translation session.
        void this.videoHandler.handleProxySettingsChanged("proxyWorkerHost");
      })
      .addEventListener("select:proxyTranslationStatus", () => {
-        // Switching proxy mode changes the request path and can turn transient
-        // failures into successes (and vice versa). Clear caches and restart
-        // request plumbing.
+        // Switching proxy mode changes request routing. Drop stale cache and
+        // stop translation so the next run starts with fresh settings.
        void this.videoHandler?.handleProxySettingsChanged(
          "proxyTranslationStatus",
        );
@ -479,7 +478,7 @@ export class UIManager {
    const settingsWasOpen =
      this.votSettingsView?.dialog?.container?.hidden === false;

-    this.videoHandler?.stopTranslation();
+    await this.videoHandler?.stopTranslation();
    this.release();
    this.initUI();
    this.initUIEvents();
@ -537,7 +536,7 @@ export class UIManager {
    debug.log("[handleTranslationBtnClick] click translationBtn");
    if (this.videoHandler.hasActiveSource()) {
      debug.log("[handleTranslationBtnClick] video has active source");
-      this.videoHandler.stopTranslation();
+      await this.videoHandler.stopTranslation();
      return this;
    }

@ -556,7 +555,7 @@ export class UIManager {
        "[handleTranslationBtnClick] translationBtn isn't in none state",
      );
      this.videoHandler.actionsAbortController.abort();
-      this.videoHandler.stopTranslation();
+      await this.videoHandler.stopTranslation();
      return this;
    }

@ -691,12 +690,81 @@ export class UIManager {
    callback(widget);
  }

+  private triggerUrlDownload(url: string, filename: string): boolean {
+    try {
+      const a = document.createElement("a");
+      a.href = url;
+      a.download = filename;
+      // Cross-origin downloads can ignore `download`; keep navigation off the
+      // current tab in that case.
+      a.target = "_blank";
+      a.rel = "noopener noreferrer";
+      a.style.display = "none";
+      document.body.appendChild(a);
+      a.click();
+      a.remove();
+      return true;
+    } catch {
+      return false;
+    }
+  }
+
+  private async tryShareBlob(blob: Blob, filename: string): Promise<boolean> {
+    const nav = typeof navigator === "undefined" ? undefined : navigator;
+    if (!nav?.share || typeof File === "undefined") {
+      return false;
+    }
+
+    let file: File;
+    try {
+      file = new File([blob], filename, {
+        type: blob.type || "application/octet-stream",
+      });
+    } catch {
+      return false;
+    }
+
+    if (
+      typeof nav.canShare === "function" &&
+      !nav.canShare({ files: [file] })
+    ) {
+      return false;
+    }
+
+    try {
+      await nav.share({ files: [file], title: filename });
+      return true;
+    } catch (err) {
+      if (err instanceof DOMException && err.name === "AbortError") {
+        return true;
+      }
+      debug.warn("[VOT] navigator.share failed, fallback to download", err);
+      return false;
+    }
+  }
+
+  private async saveBlobWithMobileShare(
+    blob: Blob,
+    filename: string,
+    preferShare: boolean,
+  ): Promise<void> {
+    if (preferShare) {
+      const shared = await this.tryShareBlob(blob, filename);
+      if (shared) {
+        return;
+      }
+    }
+
+    downloadBlob(blob, filename);
+  }
+
  private restartAudioPlayer() {
    if (!this.videoHandler) {
      return;
    }
-
-    this.videoHandler.stopTranslate();
-    this.videoHandler.createPlayer();
+    void (async () => {
+      await this.videoHandler?.stopTranslate();
+      this.videoHandler?.createPlayer();
+    })();
  }
 }
--- a/src/ui/views/overlay.ts
+++ b/src/ui/views/overlay.ts
@ -274,6 +274,9 @@ export class OverlayView {
      target: this.votButton.translateButton,
      content: localizationProvider.get("translateVideo"),
      position: this.votButton.tooltipPos,
+      // Keep side-tooltip direction stable for the moved button (left/right)
+      // so status/error text does not mirror to the opposite side.
+      autoLayout: false,
      hidden: direction === "row",
      bordered: false,
      parentElement: this.votOverlayPortal,
--- a/src/ui/views/settings.ts
+++ b/src/ui/views/settings.ts
@ -10,6 +10,7 @@ const SETTINGS_EVENT_KEYS: Array<keyof SettingsViewEventMap> = [
  "change:autoSubtitles",
  "change:showVideoVolume",
  "change:audioBooster",
+  "change:syncVolume",
  "change:useLivelyVoice",
  "change:subtitlesHighlightWords",
  "change:subtitlesSmartLayout",
@ -310,6 +311,7 @@ export class SettingsView {
      dispatch?.(value);
    });
  }
+
  initUI() {
    if (this.isInitialized()) {
      throw new Error("[VOT] SettingsView is already initialized");
@ -425,13 +427,16 @@ export class SettingsView {
    this.autoSetVolumeSlider = new Slider({
      labelHtml: this.autoSetVolumeCheckbox.container,
      value: autoVolume,
+      min: 0,
    });
+    const syncVolumeEnabled = Boolean(this.data.syncVolume);
    this.autoSetVolumeSlider.disabled = !this.autoSetVolumeCheckbox.checked;
    this.smartDuckingCheckbox = new Checkbox({
      labelHtml: localizationProvider.get("smartDucking"),
      checked: this.data.enabledSmartDucking ?? true,
    });
-    this.smartDuckingCheckbox.disabled = !this.autoSetVolumeCheckbox.checked;
+    this.smartDuckingCheckbox.disabled =
+      syncVolumeEnabled || !this.autoSetVolumeCheckbox.checked;
    this.showVideoVolumeSliderCheckbox = new Checkbox({
      labelHtml: localizationProvider.get("showVideoVolumeSlider"),
      checked: this.data.showVideoSlider,
@ -959,7 +964,8 @@ export class SettingsView {
      apply: (checked) => {
        this.data.enabledAutoVolume = checked;
        this.autoSetVolumeSlider.disabled = !checked;
-        this.smartDuckingCheckbox.disabled = !checked;
+        this.smartDuckingCheckbox.disabled =
+          !checked || Boolean(this.syncVolumeCheckbox?.checked);
      },
      storageKey: "enabledAutoVolume",
      readPersistedValue: () => this.data.enabledAutoVolume,
@ -975,6 +981,7 @@ export class SettingsView {
      storageKey: "enabledSmartDucking",
      readPersistedValue: () => this.data.enabledSmartDucking,
      logLabel: "enabledSmartDucking",
+      afterPersist: async () => this.videoHandler?.setupAudioSettings?.(),
    });
    this.bindPersistedSetting({
      control: this.autoSetVolumeSlider,
@ -1015,10 +1022,18 @@ export class SettingsView {
      event: "change",
      apply: (checked) => {
        this.data.syncVolume = checked;
+        this.autoSetVolumeSlider.disabled =
+          !this.autoSetVolumeCheckbox?.checked;
+        this.smartDuckingCheckbox.disabled =
+          checked || !this.autoSetVolumeCheckbox?.checked;
+        if (checked && this.smartDuckingCheckbox?.checked) {
+          this.smartDuckingCheckbox.checked = false;
+        }
      },
      storageKey: "syncVolume",
      readPersistedValue: () => this.data.syncVolume,
      logLabel: "syncVolume",
+      dispatch: (checked) => this.events["change:syncVolume"].dispatch(checked),
    });
    this.bindPersistedSetting({
      control: this.downloadWithNameCheckbox,
--- a/src/utils/VideoObserver.ts
+++ b/src/utils/VideoObserver.ts
@ -564,7 +564,12 @@ export class VideoObserver {
    this.onDocumentReady = onReady;
    document.addEventListener("readystatechange", onReady);
    if (typeof queueMicrotask === "function") queueMicrotask(onReady);
-    else Promise.resolve().then(onReady);
+    else {
+      void (async () => {
+        await Promise.resolve();
+        onReady();
+      })();
+    }
  }

  disable() {
--- a/src/utils/gm.ts
+++ b/src/utils/gm.ts
@ -18,564 +18,114 @@ import debug from "./debug";
 import { isAbortError, makeAbortError } from "./errors";
 import { getHeaders } from "./utils";

+const YANDEX_API_HOST = "api.browser.yandex.ru";
+
+const scriptHandler =
+  typeof GM_info !== "undefined" ? GM_info?.scriptHandler : undefined;
+
 export const isProxyOnlyExtension =
  // The extension build provides a full GM_xmlhttpRequest implementation, so
  // we should not fall into the "proxy-only" compatibility mode.
  !(typeof IS_EXTENSION !== "undefined" && IS_EXTENSION) &&
-  !!GM_info?.scriptHandler &&
-  !nonProxyExtensions.includes(GM_info.scriptHandler);
+  !!scriptHandler &&
+  !nonProxyExtensions.includes(scriptHandler);
 export const isSupportGM4 = typeof GM !== "undefined";
 export const isUnsafeWindowAllowed = typeof unsafeWindow !== "undefined";
 export const isSupportGMXhr = typeof GM_xmlhttpRequest !== "undefined";

-const DEFAULT_TIMEOUT = 15_000;
-const YANDEX_TRANSLATE_HOST = "api.browser.yandex.ru";
-const YANDEX_MIN_TIMEOUT = 30_000;
-const YANDEX_MAX_ATTEMPTS = 2;
-const RETRYABLE_HTTP_STATUSES = new Set([408, 425, 429, 500, 502, 503, 504]);
-let gmFetchRequestSeq = 0;
-const HEADER_DEBUG_LIMIT = 32;
-const BODY_OBJECT_KEYS_DEBUG_LIMIT = 12;
-
-type RequestAttemptTrace = {
-  requestId: string;
-  attempt: number;
-  effectiveTimeoutMs: number;
-};
-
-const toUrlString = (u: string | URL | Request) => {
-  if (typeof u === "string") {
-    return u;
-  }
-
-  if (u instanceof URL) {
-    return u.href;
-  }
-
-  return u.url;
-};
-
-type NoFallbackError = {
-  __gmFetchNoFallback?: boolean;
-};
-
-function isNoFallbackError(err: unknown): err is NoFallbackError {
-  return (
-    !!err &&
-    typeof err === "object" &&
-    "__gmFetchNoFallback" in (err as Record<string, unknown>)
-  );
+function shouldUseGmXhr(url: string): boolean {
+  // These endpoints are routinely blocked by page-world CORS. Going through
+  // native fetch first only adds noisy console errors and an extra failed hop.
+  return url.includes(YANDEX_API_HOST);
 }

-function markNoFallbackError(err: unknown): void {
-  if (!err || typeof err !== "object") {
-    return;
-  }
-
-  (err as NoFallbackError).__gmFetchNoFallback = true;
-}
-
-function isYandexTranslateRequest(urlStr: string): boolean {
-  try {
-    return new URL(urlStr).hostname === YANDEX_TRANSLATE_HOST;
-  } catch {
-    return urlStr.includes(YANDEX_TRANSLATE_HOST);
-  }
-}
-
-const forceGmXhr = (urlStr: string) => isYandexTranslateRequest(urlStr);
-
-function getEffectiveTimeoutMs(urlStr: string, timeoutMs: number): number {
-  if (!isYandexTranslateRequest(urlStr)) return timeoutMs;
-  return Math.max(timeoutMs, YANDEX_MIN_TIMEOUT);
-}
-
-function makeRequestId(): string {
-  gmFetchRequestSeq += 1;
-  return `gm_fetch_${Date.now()}_${gmFetchRequestSeq}`;
-}
-
-function isRetryableError(
-  err: unknown,
-  signal?: AbortSignal,
-): err is Error | DOMException {
-  if ((err as any)?.__gmFetchNoFallback) return false;
-  if (signal?.aborted) return false;
-  if (isAbortError(err)) return true;
-  if (!(err instanceof Error)) return false;
-  const msg = err.message.toLowerCase();
-  return (
-    msg.includes("timeout") ||
-    msg.includes("network") ||
-    msg.includes("failed to fetch") ||
-    msg.includes("load failed") ||
-    msg.includes("bridge port disconnected")
-  );
-}
-
-function shouldRetryResponseStatus(
+async function gmXhrFetch(
  urlStr: string,
-  status: number,
-  attempt: number,
-  maxAttempts: number,
-): boolean {
-  return (
-    isYandexTranslateRequest(urlStr) &&
-    attempt < maxAttempts &&
-    RETRYABLE_HTTP_STATUSES.has(status)
-  );
-}
-
-function shouldRetryRequestError(
-  urlStr: string,
-  err: unknown,
-  attempt: number,
-  maxAttempts: number,
-  signal?: AbortSignal,
-): boolean {
-  return (
-    isYandexTranslateRequest(urlStr) &&
-    attempt < maxAttempts &&
-    isRetryableError(err, signal)
-  );
-}
-
-function getBodyDebugInfo(body: RequestInit["body"]) {
-  if (body == null) return { type: "none", size: 0 };
-  if (typeof body === "string") {
-    return {
-      type: "string",
-      size: body.length,
-      looksLikeObjectString: /^\[object [^\]]+\]$/.test(body.trim()),
-    };
-  }
-  if (body instanceof URLSearchParams)
-    return { type: "URLSearchParams", size: body.toString().length };
-  if (body instanceof FormData) return { type: "FormData", size: -1 };
-  if (body instanceof Blob) return { type: "Blob", size: body.size };
-  if (body instanceof ArrayBuffer)
-    return { type: "ArrayBuffer", size: body.byteLength };
-  if (ArrayBuffer.isView(body))
-    return {
-      type: body.constructor?.name ?? "TypedArray",
-      size: body.byteLength,
-    };
-  if (typeof ReadableStream !== "undefined" && body instanceof ReadableStream) {
-    return { type: "ReadableStream", size: -1 };
-  }
-  const objectTag = (() => {
-    try {
-      return Object.prototype.toString.call(body);
-    } catch {
-      return null;
-    }
-  })();
-  const ctor = (() => {
-    try {
-      const ctorName = (body as any)?.constructor?.name;
-      return typeof ctorName === "string" ? ctorName : null;
-    } catch {
-      return null;
-    }
-  })();
-  const keys =
-    body && typeof body === "object"
-      ? Object.keys(body as unknown as Record<string, unknown>).slice(
-          0,
-          BODY_OBJECT_KEYS_DEBUG_LIMIT,
-        )
-      : undefined;
-  return { type: typeof body, size: -1, objectTag, ctor, keys };
-}
-
-function getHeaderDebugInfo(headers: HeadersInit | undefined) {
-  if (!headers) {
-    return {
-      headerCount: 0,
-      headerNames: [] as string[],
-      contentType: null as string | null,
-    };
-  }
-
-  const names: string[] = [];
-  let contentType: string | null = null;
-
-  const addHeader = (name: string, value: string) => {
-    const normalized = String(name || "").trim();
-    if (!normalized) return;
-    names.push(normalized);
-    if (normalized.toLowerCase() === "content-type" && contentType === null) {
-      contentType = String(value);
-    }
-  };
-
-  try {
-    if (headers instanceof Headers) {
-      for (const [name, value] of headers.entries()) addHeader(name, value);
-    } else if (Array.isArray(headers)) {
-      for (const pair of headers) {
-        if (!Array.isArray(pair) || pair.length < 2) continue;
-        addHeader(String(pair[0]), String(pair[1]));
-      }
-    } else {
-      for (const [name, value] of Object.entries(headers)) {
-        addHeader(name, String(value));
-      }
-    }
-  } catch {
-    return {
-      headerCount: -1,
-      headerNames: [] as string[],
-      contentType: null as string | null,
-    };
-  }
-
-  return {
-    headerCount: names.length,
-    headerNames: names.slice(0, HEADER_DEBUG_LIMIT),
-    contentType,
-  };
-}
-
-function parseRawHeaders(raw = "") {
-  const out: Record<string, string> = {};
-  for (const line of raw.split(/\r?\n/)) {
-    const m = /^([\w!#$%&'*+.^`|~-]+)\s*:\s*(.*)$/.exec(line);
-    if (m) out[m[1].toLowerCase()] = m[2];
-  }
-  return out;
-}
-
-async function nativeFetchWithTimeout(
-  url: string | URL | Request,
-  init: RequestInit,
-  timeoutMs: number,
-  trace?: RequestAttemptTrace,
+  timeout: number,
+  fetchOptions: Omit<FetchOpts, "timeout">,
 ): Promise<Response> {
-  const { signal, didTimeout, cleanup } = createTimeoutSignal(
-    timeoutMs,
-    init.signal,
-  );
-
-  try {
-    debug.log("[VOT][GM_fetch][native] start", {
-      url: toUrlString(url),
-      method: init.method ?? "GET",
-      timeoutMs,
-      requestId: trace?.requestId,
-      attempt: trace?.attempt,
-      effectiveTimeoutMs: trace?.effectiveTimeoutMs,
-      credentials: init.credentials ?? "same-origin",
-      mode: init.mode ?? "cors",
-      ...getHeaderDebugInfo(init.headers),
-      ...getBodyDebugInfo(init.body),
-    });
-    return await fetch(url, { ...init, signal });
-  } catch (e) {
-    debug.error("[VOT][GM_fetch][native] error", {
-      url: toUrlString(url),
-      message: e instanceof Error ? e.message : String(e),
-      requestId: trace?.requestId,
-      attempt: trace?.attempt,
-      effectiveTimeoutMs: trace?.effectiveTimeoutMs,
-      isAbortError: isAbortError(e),
-      signalAborted: !!init.signal?.aborted,
-      didTimeout: didTimeout(),
-    });
-    if (isAbortError(e) && !didTimeout() && init.signal?.aborted) {
-      markNoFallbackError(e);
-    }
-    throw e;
-  } finally {
-    cleanup();
-  }
-}
-
-function gmXhrFetch(
-  urlStr: string,
-  init: RequestInit,
-  timeoutMs: number,
-  fetchErrForAbortReuse?: unknown,
-  trace?: RequestAttemptTrace,
-): Promise<Response> {
-  const headers = getHeaders(init.headers);
-  const method = (init.method ?? "GET") as HttpMethod;
-  const supportsReadableStream = typeof ReadableStream !== "undefined";
-  // Yandex API requests are small protobuf payloads and don't benefit from
-  // progressive streaming. Using a single terminal payload avoids races where
-  // late abort/timeout events can poison the response body read.
-  const useProgressStream = supportsReadableStream && !forceGmXhr(urlStr);
-
-  // Align cookie behavior with fetch():
-  // - credentials: 'include' => send cookies/auth headers cross-site
-  // - credentials: 'omit'    => do not send cookies
-  // Many userscript managers support `withCredentials` / `anonymous`.
-  // Unsupported flags are ignored by engines that don't implement them.
-  const credentials = init.credentials;
-  const withCredentials = credentials === "include" ? true : undefined;
-  const anonymous = credentials === "omit" ? true : undefined;
-
-  return new Promise((resolve, reject) => {
-    let responseResolved = false;
-    let req: { abort?(): void } | undefined;
-
-    let streamCtrl: ReadableStreamDefaultController<Uint8Array> | undefined;
-    let seenBytes = 0;
-
-    const cleanup = () => init.signal?.removeEventListener("abort", onAbort);
-
-    const resolveResponse = (
-      body: BodyInit | null,
-      status: number,
-      statusText: string,
-      rawHeaders?: string,
-    ) => {
-      if (responseResolved) return;
-      responseResolved = true;
-      debug.log("[VOT][GM_fetch][xhr] resolve", {
-        url: urlStr,
-        method,
-        requestId: trace?.requestId,
-        attempt: trace?.attempt,
-        effectiveTimeoutMs: trace?.effectiveTimeoutMs,
-        status,
-        statusText,
-        hasBody: body != null,
-      });
-      resolve(
-        new Response(body, {
-          status,
-          statusText,
-          headers: parseRawHeaders(rawHeaders),
-        }),
-      );
-    };
-
-    const fail = (err: unknown) => {
-      if (responseResolved && !useProgressStream) {
-        cleanup();
-        debug.warn("[VOT][GM_fetch][xhr] late terminal event after resolve", {
-          url: urlStr,
-          method,
-          requestId: trace?.requestId,
-          attempt: trace?.attempt,
-          effectiveTimeoutMs: trace?.effectiveTimeoutMs,
-          message: err instanceof Error ? err.message : String(err),
-        });
-        return;
-      }
-      cleanup();
-      debug.error("[VOT][GM_fetch][xhr] fail", {
-        url: urlStr,
-        method,
-        requestId: trace?.requestId,
-        attempt: trace?.attempt,
-        effectiveTimeoutMs: trace?.effectiveTimeoutMs,
-        message: err instanceof Error ? err.message : String(err),
-      });
-      if (useProgressStream) streamCtrl?.error(err);
-      if (!responseResolved) reject(err);
-    };
-
-    const onAbort = () => {
-      req?.abort?.();
-      const abortErr =
-        fetchErrForAbortReuse && isAbortError(fetchErrForAbortReuse)
-          ? (fetchErrForAbortReuse as any)
-          : makeAbortError();
-      fail(abortErr);
-    };
-
-    if (init.signal) {
-      if (init.signal.aborted) return onAbort();
-      init.signal.addEventListener("abort", onAbort, { once: true });
-    }
-
-    debug.log("[VOT][GM_fetch][xhr] start", {
-      url: urlStr,
-      method,
-      timeoutMs,
-      requestId: trace?.requestId,
-      attempt: trace?.attempt,
-      effectiveTimeoutMs: trace?.effectiveTimeoutMs,
-      responseType: "arraybuffer",
-      withCredentials: withCredentials ?? false,
-      anonymous: anonymous ?? false,
-      useProgressStream,
-      ...getHeaderDebugInfo(headers),
-      ...getBodyDebugInfo(init.body),
-    });
-
-    if (
-      typeof init.body === "string" &&
-      /^\[object [^\]]+\]$/.test(init.body.trim())
-    ) {
-      const contentType = getHeaderDebugInfo(headers).contentType;
-      debug.warn("[VOT][GM_fetch][xhr] suspicious body string before request", {
-        url: urlStr,
-        method,
-        requestId: trace?.requestId,
-        attempt: trace?.attempt,
-        contentType,
-        body: init.body,
-      });
-    }
-
-    const stream = useProgressStream
-      ? new ReadableStream<Uint8Array>({
-          start(controller) {
-            streamCtrl = controller;
-          },
-          cancel() {
-            req?.abort?.();
-          },
-        })
-      : null;
-
-    /**
-     * Pushes new bytes into the ReadableStream.
-     *
-     * Userscript managers typically expose the *cumulative* `response`
-     * ArrayBuffer on progress events. Our extension shim can emit either:
-     *   - `progress.response`: cumulative ArrayBuffer (TM-like)
-     *   - `progress.chunk`: incremental ArrayBuffer chunk (more efficient)
-     */
-    const pushNewBytes = (evtOrResp: any) => {
-      if (!useProgressStream || !streamCtrl) return;
-
-      // Extension-optimized mode: pass only the incremental chunk.
-      const chunk = evtOrResp?.chunk;
-      if (chunk && typeof chunk !== "string") {
-        const u8 = new Uint8Array(chunk as ArrayBuffer);
-        if (u8.byteLength) {
-          streamCtrl.enqueue(u8);
-          seenBytes += u8.byteLength;
-        }
-        return;
-      }
-
-      // Classic GM/TM mode: pass the cumulative response buffer.
-      const resp = evtOrResp?.response ?? evtOrResp;
-      if (!resp || typeof resp === "string") return;
-
-      const u8 = new Uint8Array(resp as ArrayBuffer);
-      if (u8.byteLength <= seenBytes) return;
-
-      streamCtrl.enqueue(u8.slice(seenBytes));
-      seenBytes = u8.byteLength;
-    };
+  const headers = getHeaders(fetchOptions.headers);

+  return await new Promise((resolve, reject) => {
    const gmXhr =
      typeof GM_xmlhttpRequest !== "undefined"
        ? GM_xmlhttpRequest
        : (globalThis as any).GM_xmlhttpRequest;

    if (typeof gmXhr !== "function") {
-      throw new TypeError("GM_xmlhttpRequest is not available");
+      reject(new TypeError("GM_xmlhttpRequest is not available"));
+      return;
    }

-    req = gmXhr({
-      method,
+    let settled = false;
+    let onAbort: (() => void) | undefined;
+    const cleanupAbort = () => {
+      if (onAbort) {
+        fetchOptions.signal?.removeEventListener("abort", onAbort);
+      }
+    };
+    const failOnce = (error: Error) => {
+      if (settled) return;
+      settled = true;
+      cleanupAbort();
+      reject(error);
+    };
+
+    const request = gmXhr({
+      method: (fetchOptions.method || "GET") as HttpMethod,
      url: urlStr,
+      responseType: "blob" as any,
+      data: fetchOptions.body as any,
+      timeout,
      headers,
-      data: init.body as any,
-      withCredentials,
-      anonymous,
-      timeout: timeoutMs,
-      responseType: "arraybuffer" as any,
-
-      onprogress: useProgressStream
-        ? (p) => {
-            const progress = p as {
-              loaded?: number;
-              total?: number;
-              status?: number;
-              statusText?: string;
-              responseHeaders?: string;
-              response?: ArrayBuffer | string | null;
-            };
-            debug.log("[VOT][GM_fetch][xhr] progress", {
-              url: urlStr,
-              method,
-              requestId: trace?.requestId,
-              attempt: trace?.attempt,
-              loaded: progress.loaded ?? null,
-              total: progress.total ?? null,
-              status: progress.status ?? null,
-            });
-            if (!stream) return;
-            if (!responseResolved) {
-              resolveResponse(
-                stream,
-                progress.status,
-                progress.statusText,
-                progress.responseHeaders,
-              );
+      onload: (resp) => {
+        if (settled) return;
+        settled = true;
+        cleanupAbort();
+        const responseHeaders = String(resp.responseHeaders || "")
+          .split(/\r?\n/)
+          .reduce<Record<string, string>>((acc, line) => {
+            const [, key, value] = line.match(/^([\w-]+):\s*(.+)$/) || [];
+            if (key) {
+              acc[key] = value;
            }
-            pushNewBytes(progress);
-          }
-        : undefined,
+            return acc;
+          }, {});

-      onload: (r) => {
-        cleanup();
-        debug.log("[VOT][GM_fetch][xhr] onload", {
-          url: urlStr,
-          method,
-          requestId: trace?.requestId,
-          attempt: trace?.attempt,
-          effectiveTimeoutMs: trace?.effectiveTimeoutMs,
-          status: r.status,
-          statusText: r.statusText,
-          responseType: "arraybuffer",
-          responseSize:
-            r.response && typeof r.response !== "string"
-              ? ((r.response as ArrayBuffer).byteLength ?? null)
-              : null,
+        const response = new Response(resp.response as Blob, {
+          status: resp.status,
+          headers: responseHeaders,
        });

-        if (useProgressStream) {
-          if (!responseResolved) {
-            if (!stream) return;
-            resolveResponse(stream, r.status, r.statusText, r.responseHeaders);
-          }
-          pushNewBytes(r);
-          streamCtrl?.close();
-          return;
-        }
-
-        resolveResponse(
-          r.response && typeof r.response !== "string"
-            ? (r.response as ArrayBuffer)
-            : null,
-          r.status,
-          r.statusText,
-          r.responseHeaders,
-        );
-      },
-
-      onerror: fail,
-      ontimeout: () => {
-        debug.error("[VOT][GM_fetch][xhr] timeout", {
-          url: urlStr,
-          method,
-          timeoutMs,
-          requestId: trace?.requestId,
-          attempt: trace?.attempt,
-          effectiveTimeoutMs: trace?.effectiveTimeoutMs,
+        // Response has empty url by default (readonly).
+        // Keep parity with classic fetch by exposing final URL.
+        Object.defineProperty(response, "url", {
+          value: resp.finalUrl ?? "",
        });
-        fail(new Error("GM_xmlhttpRequest timeout"));
-      },
-      onabort: () => {
-        debug.warn("[VOT][GM_fetch][xhr] abort", {
-          url: urlStr,
-          method,
-          requestId: trace?.requestId,
-          attempt: trace?.attempt,
-          effectiveTimeoutMs: trace?.effectiveTimeoutMs,
-        });
-        fail(makeAbortError());
+
+        resolve(response);
      },
+      ontimeout: () => failOnce(new Error("Timeout")),
+      onerror: (error: unknown) => failOnce(new Error(String(error))),
+      onabort: () => failOnce(makeAbortError()),
    });
+
+    onAbort = () => {
+      try {
+        request?.abort?.();
+      } catch {
+        // ignore abort races
+      }
+      failOnce(makeAbortError());
+    };
+
+    if (fetchOptions.signal) {
+      if (fetchOptions.signal.aborted) {
+        onAbort();
+        return;
+      }
+      fetchOptions.signal.addEventListener("abort", onAbort, { once: true });
+    }
  });
 }

@ -583,172 +133,35 @@ export async function GM_fetch(
  url: string | URL | Request,
  opts: FetchOpts = {},
 ): Promise<Response> {
-  const { timeout = DEFAULT_TIMEOUT, ...init } = opts;
-  const urlStr = toUrlString(url);
+  const { timeout = 15_000, ...fetchOptions } = opts;
+  const urlStr =
+    typeof url === "string" ? url : url instanceof URL ? url.href : url.url;

-  const shouldForce = isSupportGMXhr && forceGmXhr(urlStr);
-  const effectiveTimeoutMs = getEffectiveTimeoutMs(urlStr, timeout);
-  const requestId = makeRequestId();
-  const maxAttempts = isYandexTranslateRequest(urlStr)
-    ? YANDEX_MAX_ATTEMPTS
-    : 1;
-  const requestMeta = {
-    url: urlStr,
-    method: init.method ?? "GET",
-    timeoutMs: timeout,
-    effectiveTimeoutMs,
-    requestId,
-    shouldForceGmXhr: shouldForce,
-    canUseGmXhr: isSupportGMXhr,
-    ...getHeaderDebugInfo(init.headers),
-    ...getBodyDebugInfo(init.body),
-  };
-
-  let lastError: unknown;
-
-  for (let attempt = 1; attempt <= maxAttempts; attempt += 1) {
-    const trace: RequestAttemptTrace = {
-      requestId,
-      attempt,
-      effectiveTimeoutMs,
-    };
-    debug.log("[VOT][GM_fetch] start", { ...requestMeta, attempt });
-
-    try {
-      if (!shouldForce) {
-        const res = await nativeFetchWithTimeout(
-          url,
-          init,
-          effectiveTimeoutMs,
-          trace,
-        );
-        debug.log("[VOT][GM_fetch] native response", {
-          ...requestMeta,
-          attempt,
-          status: res.status,
-          statusText: res.statusText,
-          type: res.type,
-          redirected: res.redirected,
-        });
-
-        // If the caller requested `no-cors` (or the browser downgraded the
-        // request), fetch() can return an opaque response (status 0) which
-        // cannot be read. In the userscript environment GM_xmlhttpRequest is
-        // commonly used as a CORS-bypass for media downloads; mirror that
-        // behaviour here to avoid false "download failed" paths.
-        if (
-          isSupportGMXhr &&
-          (res.type === "opaque" ||
-            res.type === "opaqueredirect" ||
-            res.status === 0)
-        ) {
-          debug.log(
-            "GM_fetch got an opaque/blocked response; retrying via GM_xmlhttpRequest",
-            { ...requestMeta, attempt },
-          );
-          const xhrRes = await gmXhrFetch(
-            urlStr,
-            init,
-            effectiveTimeoutMs,
-            undefined,
-            trace,
-          );
-          if (
-            shouldRetryResponseStatus(
-              urlStr,
-              xhrRes.status,
-              attempt,
-              maxAttempts,
-            )
-          ) {
-            debug.warn("[VOT][GM_fetch] retrying after retryable XHR status", {
-              ...requestMeta,
-              attempt,
-              status: xhrRes.status,
-            });
-            continue;
-          }
-          return xhrRes;
-        }
-
-        if (
-          shouldRetryResponseStatus(urlStr, res.status, attempt, maxAttempts)
-        ) {
-          debug.warn("[VOT][GM_fetch] retrying after retryable native status", {
-            ...requestMeta,
-            attempt,
-            status: res.status,
-          });
-          continue;
-        }
-
-        return res;
-      }
-      throw new Error("Force GM_xmlhttpRequest");
-    } catch (e) {
-      if (isNoFallbackError(e) && e.__gmFetchNoFallback) throw e;
-      if (!isSupportGMXhr) {
-        if (
-          shouldRetryRequestError(urlStr, e, attempt, maxAttempts, init.signal)
-        ) {
-          debug.warn("[VOT][GM_fetch] retrying after native error", {
-            ...requestMeta,
-            attempt,
-            reason: e instanceof Error ? e.message : String(e),
-          });
-          lastError = e;
-          continue;
-        }
-        throw e;
-      }
-
-      debug.warn("[VOT][GM_fetch] fallback to GM_xmlhttpRequest", {
-        ...requestMeta,
-        attempt,
-        reason: e instanceof Error ? e.message : String(e),
-      });
-
-      try {
-        const res = await gmXhrFetch(
-          urlStr,
-          init,
-          effectiveTimeoutMs,
-          e,
-          trace,
-        );
-        if (
-          shouldRetryResponseStatus(urlStr, res.status, attempt, maxAttempts)
-        ) {
-          debug.warn("[VOT][GM_fetch] retrying after retryable XHR status", {
-            ...requestMeta,
-            attempt,
-            status: res.status,
-          });
-          continue;
-        }
-        return res;
-      } catch (error_) {
-        if (
-          shouldRetryRequestError(
-            urlStr,
-            error_,
-            attempt,
-            maxAttempts,
-            init.signal,
-          )
-        ) {
-          debug.warn("[VOT][GM_fetch] retrying after XHR error", {
-            ...requestMeta,
-            attempt,
-            reason: error_ instanceof Error ? error_.message : String(error_),
-          });
-          lastError = error_;
-          continue;
-        }
-        throw error_;
-      }
-    }
+  if (shouldUseGmXhr(urlStr)) {
+    debug.log("GM_fetch: routing request via GM_xmlhttpRequest", {
+      host: YANDEX_API_HOST,
+      url: urlStr,
+    });
+    return await gmXhrFetch(urlStr, timeout, fetchOptions);
  }

-  throw lastError ?? new Error("GM_fetch failed");
+  const { signal, cleanup } = createTimeoutSignal(timeout, fetchOptions.signal);
+  try {
+    return await fetch(url, {
+      signal,
+      ...fetchOptions,
+    });
+  } catch (err) {
+    if (isAbortError(err) || fetchOptions.signal?.aborted) {
+      throw err;
+    }
+    // If fetch fails, retry via GM_xmlhttpRequest.
+    debug.log(
+      "GM_fetch preventing CORS by GM_xmlhttpRequest",
+      (err as Error)?.message ?? String(err),
+    );
+    return await gmXhrFetch(urlStr, timeout, fetchOptions);
+  } finally {
+    cleanup();
+  }
 }
--- a/src/utils/intervalIdleChecker.ts
+++ b/src/utils/intervalIdleChecker.ts
@ -51,7 +51,10 @@ function getDefaultRuntime(): IntervalIdleRuntime {
        queueMicrotask(fn);
        return;
      }
-      Promise.resolve().then(fn);
+      void (async () => {
+        await Promise.resolve();
+        fn();
+      })();
    },
    isDocumentHidden: () =>
      typeof document !== "undefined" && typeof document.hidden === "boolean"
--- a/src/utils/volumeLink.ts
+++ b/src/utils/volumeLink.ts
@ -0,0 +1,95 @@
+import { clampInt, clampPercentInt } from "./volume";
+
+export type VolumeLinkState = {
+  initialized: boolean;
+  lastVideoPercent: number;
+  lastTranslationPercent: number;
+};
+
+export type VolumeLinkDirection = "translation" | "video";
+
+type ApplyVolumeLinkDeltaInput = {
+  state: VolumeLinkState;
+  fromType: VolumeLinkDirection;
+  newVolume: number;
+  currentVideo: number;
+  currentTranslation: number;
+  translationMin: number;
+  translationMax: number;
+};
+
+export type ApplyVolumeLinkDeltaResult = {
+  nextVideo?: number;
+  nextTranslation?: number;
+};
+
+export function syncVideoLinkSnapshot(
+  state: VolumeLinkState,
+  volumePercent: number,
+): void {
+  const normalized = clampPercentInt(volumePercent);
+  state.lastVideoPercent = normalized;
+}
+
+export function syncTranslationLinkSnapshot(
+  state: VolumeLinkState,
+  volumePercent: number,
+): void {
+  const numeric = Number(volumePercent);
+  if (!Number.isFinite(numeric)) {
+    return;
+  }
+  const normalized = Math.max(0, Math.round(numeric));
+  state.lastTranslationPercent = normalized;
+}
+
+/**
+ * Applies delta-based volume linking and mutates `state` in place.
+ *
+ * Rules:
+ * - "video" initiator: translation changes by the same delta as video.
+ * - "translation" initiator: video changes by the same delta as translation.
+ *
+ * This preserves relative offset between sliders (until clamped by bounds),
+ * instead of forcing a 1:1 mirror.
+ */
+export function applyVolumeLinkDelta({
+  state,
+  fromType,
+  newVolume,
+  currentVideo,
+  currentTranslation,
+  translationMin,
+  translationMax,
+}: ApplyVolumeLinkDeltaInput): ApplyVolumeLinkDeltaResult {
+  if (!state.initialized) {
+    state.lastVideoPercent = Number(currentVideo);
+    state.lastTranslationPercent = Number(currentTranslation);
+    state.initialized = true;
+  }
+
+  if (fromType === "video") {
+    const normalizedVideo = clampPercentInt(newVolume);
+    const delta = normalizedVideo - clampPercentInt(state.lastVideoPercent);
+    state.lastVideoPercent = normalizedVideo;
+    const nextTranslation = clampInt(
+      state.lastTranslationPercent + delta,
+      translationMin,
+      translationMax,
+    );
+    state.lastTranslationPercent = nextTranslation;
+    return { nextTranslation };
+  }
+
+  const normalizedTranslation = clampInt(
+    Number.isFinite(newVolume) ? newVolume : currentTranslation,
+    translationMin,
+    translationMax,
+  );
+  const delta = normalizedTranslation - state.lastTranslationPercent;
+  state.lastTranslationPercent = normalizedTranslation;
+  const nextVideo = clampPercentInt(state.lastVideoPercent + delta);
+  state.lastVideoPercent = nextVideo;
+
+  return { nextVideo };
+}
--- a/src/videoHandler/modules/events.ts
+++ b/src/videoHandler/modules/events.ts
@ -79,6 +79,9 @@ function syncAudioTranslationVolumeFromVideo(
  if (options.skipYouTubeLikeHosts && isYouTubeLikeHost(self.site.host)) {
    return;
  }
+  // While smart ducking is active, the script drives video volume itself.
+  // Ignore observer-driven sync to avoid feedback loops/jitter.
+  if (typeof self.smartVolumeDuckingInterval === "number") return;
  if (!self.data?.syncVolume || !self.audioPlayer?.player?.src) return;
  if (self.isLikelyInternalVideoVolumeChange(videoPercent)) return;
  self.syncVolumeWrapper("video", videoPercent);
@ -373,7 +376,7 @@ function bindVideoLifecycleEvents(ctx: ExtraEventsContext): void {
  if (self.site.host === "youtube" && !self.site.additionalData) {
    add(document, "yt-page-data-updated", () => {
      debug.log("yt-page-data-updated");
-      if (!globalThis.location.pathname.includes("/shorts/")) return;
+      if (!globalThis.location.pathname.startsWith("/shorts/")) return;
      queueSetCanPlay();
    });
  }
--- a/src/videoHandler/modules/translation.ts
+++ b/src/videoHandler/modules/translation.ts
@ -42,15 +42,255 @@ type StopSmartVolumeDuckingOptions = {
 };

 type AudioPlayerLike = {
-  getAudioRms?: () => number | undefined;
+  audio?: HTMLMediaElement;
+  audioElement?: HTMLMediaElement;
+  gainNode?: AudioNode;
+  audioSource?: AudioNode;
+  mediaElementSource?: AudioNode;
+};
+
+type SmartDuckingAnalyserState = {
  analyser?: AnalyserNode;
  analyserFloatData?: Float32Array<ArrayBuffer>;
  analyserData?: Uint8Array<ArrayBuffer>;
-  getMediaElement?: () => HTMLMediaElement | undefined;
-  audio?: HTMLMediaElement;
-  audioElement?: HTMLMediaElement;
+  connectedInputNode?: AudioNode;
+  mediaElement?: HTMLMediaElement;
+  audioContext?: AudioContext;
+  createdMediaSource?: MediaElementAudioSourceNode;
+  mediaSourceCreationFailed?: boolean;
 };

+const smartDuckingAnalyserState = new WeakMap<
+  VideoHandler,
+  SmartDuckingAnalyserState
+>();
+
+function isAudioNode(node: unknown): node is AudioNode {
+  if (!node || typeof node !== "object") return false;
+  const candidate = node as { connect?: unknown; disconnect?: unknown };
+  return (
+    typeof candidate.connect === "function" &&
+    typeof candidate.disconnect === "function"
+  );
+}
+
+function getPlayerMediaElement(
+  player?: AudioPlayerLike,
+): HTMLMediaElement | undefined {
+  return player?.audio ?? player?.audioElement;
+}
+
+async function resumePlayerAudioContextIfNeeded(
+  handler: VideoHandler,
+): Promise<"not-needed" | "resumed" | "timeout" | "failed"> {
+  const ctx = handler.audioPlayer?.audioContext;
+  if (!ctx || ctx.state !== "suspended") return "not-needed";
+
+  const RESUME_TIMEOUT_MS = 1500;
+
+  const resumePromise = (async (): Promise<"resumed" | "failed"> => {
+    try {
+      await ctx.resume();
+      return "resumed";
+    } catch (err) {
+      debug.log("[updateTranslation] Failed to resume AudioContext", err);
+      return "failed";
+    }
+  })();
+
+  let timeoutId: ReturnType<typeof setTimeout> | undefined;
+  const timeoutPromise = new Promise<"timeout">((resolve) => {
+    timeoutId = setTimeout(() => resolve("timeout"), RESUME_TIMEOUT_MS);
+  });
+
+  const result = await Promise.race([resumePromise, timeoutPromise]);
+  if (timeoutId !== undefined) {
+    clearTimeout(timeoutId);
+  }
+
+  if (result === "resumed") {
+    debug.log("[updateTranslation] AudioContext resumed");
+  } else if (result === "timeout") {
+    debug.log("[updateTranslation] AudioContext resume timeout");
+  }
+
+  return result;
+}
+
+async function rollbackStaleAppliedSourceIfStillCurrent(
+  handler: VideoHandler,
+  appliedSourceUrl: string | null,
+): Promise<void> {
+  if (!appliedSourceUrl || !handler.audioPlayer) return;
+
+  const player = handler.audioPlayer.player;
+  const currentSource = String(player.currentSrc || player.src || "");
+  const normalizedCurrentUrl = handler.proxifyAudio(
+    handler.unproxifyAudio(currentSource),
+  );
+  const normalizedAppliedUrl = handler.proxifyAudio(
+    handler.unproxifyAudio(appliedSourceUrl),
+  );
+  if (normalizedCurrentUrl !== normalizedAppliedUrl) return;
+
+  try {
+    await player.clear();
+    player.src = "";
+    debug.log("[updateTranslation] cleared stale partially-applied source");
+  } catch (err) {
+    debug.log("[updateTranslation] failed to clear stale source", err);
+  }
+}
+
+function getSmartDuckingAudioContext(
+  handler: VideoHandler,
+): AudioContext | undefined {
+  return handler.audioPlayer?.audioContext ?? handler.audioContext;
+}
+
+function disconnectSmartDuckingAnalyser(
+  state: SmartDuckingAnalyserState,
+): void {
+  if (state.connectedInputNode && state.analyser) {
+    try {
+      state.connectedInputNode.disconnect(state.analyser);
+    } catch {
+      // ignore
+    }
+  }
+  state.connectedInputNode = undefined;
+
+  if (state.createdMediaSource) {
+    try {
+      state.createdMediaSource.disconnect();
+    } catch {
+      // ignore
+    }
+  }
+  state.createdMediaSource = undefined;
+
+  if (state.analyser) {
+    try {
+      state.analyser.disconnect();
+    } catch {
+      // ignore
+    }
+  }
+
+  state.analyser = undefined;
+  state.analyserFloatData = undefined;
+  state.analyserData = undefined;
+  state.mediaElement = undefined;
+  state.audioContext = undefined;
+  state.mediaSourceCreationFailed = false;
+}
+
+function releaseSmartDuckingAnalyser(handler: VideoHandler): void {
+  const state = smartDuckingAnalyserState.get(handler);
+  if (!state) return;
+
+  disconnectSmartDuckingAnalyser(state);
+  smartDuckingAnalyserState.delete(handler);
+}
+
+function resolveSmartDuckingInputNode(
+  player: AudioPlayerLike | undefined,
+  media: HTMLMediaElement,
+  audioContext: AudioContext,
+  state: SmartDuckingAnalyserState,
+): AudioNode | undefined {
+  if (isAudioNode(player?.gainNode)) return player.gainNode;
+  if (isAudioNode(player?.audioSource)) return player.audioSource;
+  if (isAudioNode(player?.mediaElementSource)) return player.mediaElementSource;
+
+  if (
+    state.mediaSourceCreationFailed &&
+    state.mediaElement === media &&
+    state.audioContext === audioContext
+  ) {
+    return undefined;
+  }
+
+  if (
+    state.createdMediaSource &&
+    state.mediaElement === media &&
+    state.audioContext === audioContext
+  ) {
+    return state.createdMediaSource;
+  }
+
+  try {
+    const source = audioContext.createMediaElementSource(media);
+    state.createdMediaSource = source;
+    state.mediaSourceCreationFailed = false;
+    return source;
+  } catch (err) {
+    state.mediaSourceCreationFailed = true;
+    debug.log("[SmartDucking] failed to create media source", err);
+    return undefined;
+  }
+}
+
+function ensureSmartDuckingAnalyser(
+  handler: VideoHandler,
+  player: AudioPlayerLike | undefined,
+  media: HTMLMediaElement,
+): { analyser: AnalyserNode; state: SmartDuckingAnalyserState } | undefined {
+  const audioContext = getSmartDuckingAudioContext(handler);
+  if (!audioContext) return undefined;
+
+  let state = smartDuckingAnalyserState.get(handler);
+  if (!state) {
+    state = {};
+    smartDuckingAnalyserState.set(handler, state);
+  }
+
+  if (
+    (state.mediaElement && state.mediaElement !== media) ||
+    (state.audioContext && state.audioContext !== audioContext)
+  ) {
+    disconnectSmartDuckingAnalyser(state);
+  }
+
+  state.mediaElement = media;
+  state.audioContext = audioContext;
+
+  if (!state.analyser) {
+    const analyser = audioContext.createAnalyser();
+    analyser.fftSize = 512;
+    state.analyser = analyser;
+  }
+
+  const inputNode = resolveSmartDuckingInputNode(
+    player,
+    media,
+    audioContext,
+    state,
+  );
+  const analyser = state.analyser;
+  if (!inputNode || !analyser) return undefined;
+
+  if (state.connectedInputNode !== inputNode) {
+    if (state.connectedInputNode) {
+      try {
+        state.connectedInputNode.disconnect(analyser);
+      } catch {
+        // ignore
+      }
+    }
+
+    try {
+      inputNode.connect(analyser);
+      state.connectedInputNode = inputNode;
+    } catch (err) {
+      debug.log("[SmartDucking] failed to connect analyser", err);
+      return undefined;
+    }
+  }
+
+  return { analyser, state };
+}
+
 function readSmartDuckingRuntime(handler: VideoHandler): SmartDuckingRuntime {
  return {
    isDucked: handler.smartVolumeIsDucked,
@ -111,6 +351,8 @@ export function stopSmartVolumeDucking(
      // ignore
    }
  }
+
+  releaseSmartDuckingAnalyser(handler);
  writeSmartDuckingRuntime(handler, resetSmartDuckingRuntime());
 }

@ -118,38 +360,59 @@ function startSmartVolumeDucking(handler: VideoHandler): void {
  if (typeof globalThis === "undefined") return;
  if (typeof handler.smartVolumeDuckingInterval === "number") return;

-  writeSmartDuckingRuntime(
-    handler,
-    initSmartDuckingRuntime(handler.getVideoVolume()),
-  );
+  const currentVideoVolume = handler.getVideoVolume();
+  const baseline =
+    typeof handler.smartVolumeDuckingBaseline === "number"
+      ? handler.smartVolumeDuckingBaseline
+      : currentVideoVolume;
+
+  const runtime = initSmartDuckingRuntime(baseline);
+  if (
+    Number.isFinite(currentVideoVolume) &&
+    Number.isFinite(baseline) &&
+    currentVideoVolume <
+      baseline - SMART_DUCKING_DEFAULT_CONFIG.externalBaselineDelta01
+  ) {
+    // Resuming Smart mode from constant ducking: keep baseline untouched and
+    // continue from the already ducked state.
+    const now =
+      typeof performance !== "undefined" &&
+      typeof performance.now === "function"
+        ? performance.now()
+        : Date.now();
+    runtime.isDucked = true;
+    runtime.speechGateOpen = true;
+    runtime.lastApplied = currentVideoVolume;
+    runtime.lastSoundAt = now;
+  }
+
+  writeSmartDuckingRuntime(handler, runtime);

  handler.smartVolumeDuckingInterval = globalThis.setInterval(() => {
    smartDuckingTick(handler);
  }, SMART_DUCKING_DEFAULT_CONFIG.tickMs);
 }

-function getTranslatedAudioRms(this: VideoHandler): number | undefined {
-  const player = this.audioPlayer?.player as unknown as
+function getTranslatedAudioRms(
+  handler: VideoHandler,
+  media: HTMLMediaElement,
+): number | undefined {
+  const player = handler.audioPlayer?.player as unknown as
    | AudioPlayerLike
    | undefined;
+  const analyserBundle = ensureSmartDuckingAnalyser(handler, player, media);
+  if (!analyserBundle) return undefined;

-  // Preferred: use the helper implemented in chaimu (if available).
-  const rms = player?.getAudioRms?.();
-  if (typeof rms === "number" && Number.isFinite(rms)) return rms;
-
-  // Fallback: if the analyser is present (older builds might still expose it),
-  // compute RMS here.
-  const analyser: AnalyserNode | undefined = player?.analyser;
-  if (!analyser) return undefined;
+  const { analyser, state } = analyserBundle;

  try {
    // Use float time-domain data when available (avoids 8-bit quantization).
    if (typeof analyser.getFloatTimeDomainData === "function") {
-      let floatData = player?.analyserFloatData;
+      let floatData = state.analyserFloatData;

      if (floatData?.length !== analyser.fftSize) {
        floatData = new Float32Array(analyser.fftSize);
-        player.analyserFloatData = floatData;
+        state.analyserFloatData = floatData;
      }

      analyser.getFloatTimeDomainData(floatData);
@ -158,18 +421,13 @@ function getTranslatedAudioRms(this: VideoHandler): number | undefined {
      for (const value of floatData) {
        sum += value * value;
      }
-      return Math.sqrt(sum / floatData.length);
+      return clamp(Math.sqrt(sum / floatData.length), 0, 1);
    }

-    // Byte fallback.
-    // TS 5.9+ types `Uint8Array` with a generic ArrayBuffer type parameter. WebAudio's
-    // `getByteTimeDomainData` expects a Uint8Array; the underlying buffer type does not
-    // matter for our usage, so we cast for compatibility.
-    let data = player?.analyserData;
-
+    let data = state.analyserData;
    if (data?.length !== analyser.fftSize) {
      data = new Uint8Array(analyser.fftSize);
-      player.analyserData = data;
+      state.analyserData = data;
    }

    analyser.getByteTimeDomainData(data);
@ -179,7 +437,7 @@ function getTranslatedAudioRms(this: VideoHandler): number | undefined {
      const normalizedValue = (rawValue - 128) / 128;
      sum += normalizedValue * normalizedValue;
    }
-    return Math.sqrt(sum / data.length);
+    return clamp(Math.sqrt(sum / data.length), 0, 1);
  } catch {
    return undefined;
  }
@ -189,11 +447,20 @@ function smartDuckingTick(handler: VideoHandler): void {
  const player = handler.audioPlayer?.player as unknown as
    | AudioPlayerLike
    | undefined;
-  const media: HTMLMediaElement | undefined =
-    player?.getMediaElement?.() ??
-    // Legacy fallbacks
-    player?.audio ??
-    player?.audioElement;
+  const media = getPlayerMediaElement(player);
+  const syncVolumeEnabled = Boolean(handler.data?.syncVolume);
+  const autoVolumeEnabled =
+    Boolean(handler.data?.enabledAutoVolume) && !syncVolumeEnabled;
+  const smartEnabled =
+    (handler.data?.enabledSmartDucking ?? true) && !syncVolumeEnabled;
+
+  // Smart ducking may be disabled while interval is still active (e.g. runtime
+  // settings toggle). Switch to one-shot classic ducking immediately and stop
+  // periodic corrections so user volume changes are not overridden.
+  if (autoVolumeEnabled && !smartEnabled) {
+    setupAudioSettings.call(handler);
+    return;
+  }

  const audioIsPlaying =
    !!media &&
@ -213,15 +480,17 @@ function smartDuckingTick(handler: VideoHandler): void {
  const dynamicDuckingTarget =
    clamp(handler.data?.autoVolume ?? defaultAutoVolume, 0, 100) / 100;
  handler.smartVolumeDuckingTarget = dynamicDuckingTarget;
+  const rms =
+    audioIsPlaying && media ? getTranslatedAudioRms(handler, media) : 0;

  const decision = computeSmartDuckingStep(
    {
      nowMs: now,
      translationActive: handler.hasActiveSource(),
-      enabledAutoVolume: Boolean(handler.data?.enabledAutoVolume),
-      smartEnabled: handler.data?.enabledSmartDucking ?? true,
+      enabledAutoVolume: autoVolumeEnabled,
+      smartEnabled,
      audioIsPlaying,
-      rms: audioIsPlaying ? getTranslatedAudioRms.call(handler) : 0,
+      rms,
      currentVideoVolume,
      hostVideoActive,
      duckingTarget01: dynamicDuckingTarget,
@ -436,39 +705,21 @@ export async function handleProxySettingsChanged(
  this: VideoHandler,
  reason = "proxySettingsChanged",
 ) {
+  debug.log(`[VOT] ${reason}: clearing translation/subtitles cache`);
  try {
-    debug.log(`[VOT] ${reason}: clearing translation cache`);
    this.cacheManager.clear();
    this.activeTranslation = null;
  } catch {
    // ignore
  }

-  // Cancel any in-flight requests so a new attempt can start cleanly.
+  // Switching proxy settings should cancel any ongoing translation and leave
+  // playback in a clean, disabled state.
  try {
-    this.resetActionsAbortController(reason);
+    await this.stopTranslation();
  } catch {
    // ignore
  }
-
-  // If we're currently playing a translated audio track (non-stream),
-  // re-apply the proxy mapping and re-validate the URL.
-  try {
-    if (this.videoData?.isStream) {
-      return;
-    }
-
-    const current =
-      this.downloadTranslationUrl ||
-      this.audioPlayer?.player?.currentSrc ||
-      this.audioPlayer?.player?.src;
-
-    if (!current) return;
-
-    await this.updateTranslation(this.unproxifyAudio(current));
-  } catch (err) {
-    debug.log(`[VOT] ${reason}: failed to refresh active audio`, err);
-  }
 }

 export function isMultiMethodS3(this: VideoHandler, url: string): boolean {
@ -482,10 +733,15 @@ export async function updateTranslation(
  audioUrl: string,
  actionContext?: { gen: number; videoId: string },
 ): Promise<void> {
+  await this.waitForPendingStopTranslate();
  if (this.isActionStale(actionContext)) return;
  if (!this.audioPlayer) {
    this.createPlayer();
  }
+  if (this.audioPlayer.audioContext?.state === "closed") {
+    debug.log("[updateTranslation] AudioContext is closed, recreating player");
+    this.createPlayer();
+  }
  const normalizedTargetUrl = this.proxifyAudio(this.unproxifyAudio(audioUrl));
  const currentSource =
    this.audioPlayer.player.currentSrc || this.audioPlayer.player.src || "";
@ -502,18 +758,92 @@ export async function updateTranslation(
  }
  if (this.isActionStale(actionContext)) return;
  const shouldInitPlayer = this.audioPlayer.player.src !== nextAudioUrl;
+  let appliedSourceUrl: string | null = null;
  if (shouldInitPlayer) {
    this.audioPlayer.player.src = nextAudioUrl;
+    appliedSourceUrl = nextAudioUrl;
  }
+  let initError: unknown;
  try {
    if (shouldInitPlayer) {
-      this.audioPlayer.init();
+      await this.audioPlayer.init();
+    }
+    if (this.isActionStale(actionContext)) {
+      await rollbackStaleAppliedSourceIfStillCurrent(this, appliedSourceUrl);
+      return;
+    }
+    const resumeResult = await resumePlayerAudioContextIfNeeded(this);
+    if (resumeResult === "timeout") {
+      debug.log(
+        "[updateTranslation] continuing after AudioContext resume timeout",
+      );
+    } else if (resumeResult === "failed") {
+      debug.log(
+        "[updateTranslation] AudioContext resume failed, continue without deferred resume",
+      );
+    }
+    if (this.isActionStale(actionContext)) {
+      await rollbackStaleAppliedSourceIfStillCurrent(this, appliedSourceUrl);
+      return;
+    }
+    if (!this.video.paused && this.audioPlayer.player.src) {
+      this.audioPlayer.player.lipSync("play");
    }
  } catch (err: unknown) {
-    debug.log("this.audioPlayer.init() error", err);
-    const msg = err instanceof Error ? err.message : String(err);
-    this.transformBtn("error", msg);
+    initError = err;
  }
+
+  // Network/proxy hiccup fallback: if proxied URL failed to fetch audio data,
+  // retry once with the original direct S3 URL.
+  if (initError && shouldInitPlayer && !this.isActionStale(actionContext)) {
+    const directUrl = this.unproxifyAudio(nextAudioUrl);
+    if (directUrl !== nextAudioUrl) {
+      try {
+        debug.log(
+          "[updateTranslation] proxied audio init failed, retrying direct URL",
+        );
+        const validatedDirectUrl = await this.validateAudioUrl(
+          directUrl,
+          actionContext,
+        );
+        if (this.isActionStale(actionContext)) {
+          await rollbackStaleAppliedSourceIfStillCurrent(
+            this,
+            appliedSourceUrl,
+          );
+          return;
+        }
+        this.audioPlayer.player.src = validatedDirectUrl;
+        appliedSourceUrl = validatedDirectUrl;
+        nextAudioUrl = validatedDirectUrl;
+        await this.audioPlayer.init();
+
+        const resumeResult = await resumePlayerAudioContextIfNeeded(this);
+        if (resumeResult === "timeout" || resumeResult === "failed") {
+          debug.log(
+            "[updateTranslation] AudioContext not resumed after direct URL fallback",
+            resumeResult,
+          );
+        }
+        if (!this.video.paused && this.audioPlayer.player.src) {
+          this.audioPlayer.player.lipSync("play");
+        }
+        initError = undefined;
+      } catch (fallbackErr) {
+        initError = fallbackErr;
+      }
+    }
+  }
+
+  if (initError) {
+    debug.log("this.audioPlayer.init() error", initError);
+    await rollbackStaleAppliedSourceIfStillCurrent(this, appliedSourceUrl);
+    const msg =
+      initError instanceof Error ? initError.message : String(initError);
+    this.transformBtn("error", msg);
+    return;
+  }
+
  this.setupAudioSettings();
  this.transformBtn("success", localizationProvider.get("disableTranslate"));
  this.afterUpdateTranslation(nextAudioUrl);
@ -527,8 +857,9 @@ export async function translateFunc(
  responseLang: string,
  translationHelp?: VideoData["translationHelp"],
 ): Promise<void> {
+  await this.waitForPendingStopTranslate();
  debug.log("Run videoValidator");
-  this.videoValidator();
+  await this.videoValidator();
  // Stream translation is currently disabled; keep this parameter for API compatibility.

  // Ensure we don't start requests with a stale/aborted signal.
@ -669,6 +1000,15 @@ export async function translateFunc(
    if (this.activeTranslation?.promise === translationPromise) {
      this.activeTranslation = null;
    }
+    const overlayBtn = this.uiManager.votOverlayView?.votButton;
+    if (
+      !this.activeTranslation &&
+      overlayBtn?.loading &&
+      !this.hasActiveSource()
+    ) {
+      debug.log("[translateFunc] clearing stale loading state");
+      this.transformBtn("none", localizationProvider.get("translateVideo"));
+    }
  }
 }

@ -681,18 +1021,49 @@ export function setupAudioSettings(this: VideoHandler) {
    this.audioPlayer.player.volume = this.data.defaultVolume / 100;
  }

-  // Smart Auto-Volume ducking: lower the original video volume only when
-  // translated audio is actually playing sound, and restore it during silence.
-  if (this.data?.enabledAutoVolume) {
-    this.smartVolumeDuckingTarget =
-      clamp(this.data.autoVolume ?? defaultAutoVolume, 0, 100) / 100;
+  const autoVolumeEnabled =
+    Boolean(this.data?.enabledAutoVolume) && !this.data?.syncVolume;
+  const smartDuckingEnabled = this.data?.enabledSmartDucking ?? true;

-    // Start the ducking loop once per translation session.
-    startSmartVolumeDucking(this);
-  } else {
-    // Auto-volume toggled off -> stop ducking and restore baseline.
+  if (!autoVolumeEnabled) {
+    // Auto-volume toggled off -> restore baseline and fully reset smart ducking.
    stopSmartVolumeDucking(this, {
      restoreVolume: this.smartVolumeDuckingBaseline ?? this.volumeOnStart,
    });
+    return;
  }
+
+  const targetVolume =
+    clamp(this.data.autoVolume ?? defaultAutoVolume, 0, 100) / 100;
+  this.smartVolumeDuckingTarget = targetVolume;
+
+  if (!this.hasActiveSource()) {
+    // No active translation source yet: keep target cached for next setup call.
+    return;
+  }
+
+  if (smartDuckingEnabled) {
+    startSmartVolumeDucking(this);
+    return;
+  }
+
+  // Smart ducking disabled -> fall back to classic constant ducking.
+  if (typeof this.smartVolumeDuckingInterval === "number") {
+    clearInterval(this.smartVolumeDuckingInterval);
+    this.smartVolumeDuckingInterval = undefined;
+  }
+
+  if (typeof this.smartVolumeDuckingBaseline !== "number") {
+    this.smartVolumeDuckingBaseline = this.getVideoVolume();
+  }
+
+  const baseline = this.smartVolumeDuckingBaseline ?? this.getVideoVolume();
+  this.setVideoVolume(Math.min(baseline, targetVolume));
+
+  // Keep runtime in a neutral state in constant mode.
+  writeSmartDuckingRuntime(
+    this,
+    initSmartDuckingRuntime(this.smartVolumeDuckingBaseline),
+  );
+  this.smartVolumeIsDucked = true;
 }
--- a/vite.extension.shared.ts
+++ b/vite.extension.shared.ts
@ -14,6 +14,12 @@ export const srcDir = path.join(rootDir, "src");
 export const outBase = path.join(rootDir, "dist-ext");
 export const outTmp = path.join(outBase, "_tmp");

+const GITHUB_DIST_EXT_RAW_BASE =
+  "https://raw.githubusercontent.com/ilyhalight/voice-over-translation/master/dist-ext";
+const CHROME_UPDATES_MANIFEST_FILE = "vot-extension-chrome-updates.xml";
+const FIREFOX_UPDATES_MANIFEST_FILE = "vot-extension-firefox-updates.json";
+const FIREFOX_UPDATES_MANIFEST_URL = `${GITHUB_DIST_EXT_RAW_BASE}/${FIREFOX_UPDATES_MANIFEST_FILE}`;
+
 export type ExtensionBuildTarget = "chrome" | "firefox" | "all";

 export interface ExtensionHeaders {
@ -409,7 +415,7 @@ function getFirefoxAddonId(): string {
  return (
    process.env.FIREFOX_ADDON_ID ||
    process.env.GECKO_ID ||
-    "vot-extension@local"
+    "vot-extension@firefox"
  );
 }

@ -443,6 +449,10 @@ function getFirefoxDataCollectionPermissions(): {
  };
 }

+function getFirefoxXpiRawUrl(version: string): string {
+  return `${GITHUB_DIST_EXT_RAW_BASE}/vot-extension-firefox-${version}.xpi`;
+}
+
 function buildManifestFirefox({
  headers,
  includeWorld,
@ -458,6 +468,7 @@ function buildManifestFirefox({
    defaultIcon[64] = "icons/icon-64.png";
  }

+  delete manifest.update_url;
  delete manifest.background;
  manifest.background = {
    scripts: ["background.js"],
@ -465,6 +476,7 @@ function buildManifestFirefox({
  manifest.browser_specific_settings = {
    gecko: {
      id: getFirefoxAddonId(),
+      update_url: FIREFOX_UPDATES_MANIFEST_URL,
      strict_min_version: getFirefoxStrictMinVersion(),
      data_collection_permissions: getFirefoxDataCollectionPermissions(),
    },
@ -487,6 +499,36 @@ async function writeManifest(
  );
 }

+async function writeFirefoxUpdatesManifest({
+  version,
+  addonId,
+}: {
+  version: string;
+  addonId: string;
+}): Promise<string> {
+  const updatesManifestPath = path.join(outBase, FIREFOX_UPDATES_MANIFEST_FILE);
+  const updatesManifest = {
+    addons: {
+      [addonId]: {
+        updates: [
+          {
+            version,
+            update_link: getFirefoxXpiRawUrl(version),
+          },
+        ],
+      },
+    },
+  };
+
+  await fs.writeFile(
+    updatesManifestPath,
+    JSON.stringify(updatesManifest, null, 3),
+    "utf8",
+  );
+
+  return updatesManifestPath;
+}
+
 async function zipDir(sourceDirPath: string, outZipPath: string): Promise<void> {
  await fs.rm(outZipPath, { force: true });
  await fs.mkdir(path.dirname(outZipPath), { recursive: true });
@ -528,10 +570,12 @@ async function maybeBuildCrx({
 }: {
  sourceDir: string;
  version: string;
-}): Promise<string> {
+}): Promise<{ crxPath: string }> {
+  const customKeyPath = process.env.CHROME_CRX_KEY_PATH?.trim() || null;
+  const useTemporaryKey = !customKeyPath;
  const keyPath = path.resolve(
    rootDir,
-    process.env.CHROME_CRX_KEY_PATH || path.join(outBase, "vot-extension-chrome.pem"),
+    customKeyPath || path.join(outTmp, "vot-extension-chrome.pem"),
  );
  await fs.mkdir(path.dirname(keyPath), { recursive: true });

@ -540,8 +584,29 @@ async function maybeBuildCrx({
    throw new Error(`CRX builder not found: ${crx3Bin}. Install dependencies first.`);
  }
  const outCrx = path.join(outBase, `vot-extension-chrome-${version}.crx`);
-  await runCmd(crx3Bin, ["-p", keyPath, "-o", outCrx, sourceDir], rootDir);
-  return outCrx;
+  try {
+    await runCmd(
+      crx3Bin,
+      [
+        "-p",
+        keyPath,
+        "-o",
+        outCrx,
+        "--appVersion",
+        version,
+        sourceDir,
+      ],
+      rootDir,
+    );
+  } finally {
+    if (useTemporaryKey) {
+      await fs.rm(keyPath, { force: true });
+      await fs.rm(path.join(outBase, "vot-extension-chrome.pem"), { force: true });
+    }
+  }
+  return {
+    crxPath: outCrx,
+  };
 }

 function isValidMatchPattern(pattern: string): boolean {
@ -607,6 +672,9 @@ async function verifyOne(browserName: "chrome" | "firefox"): Promise<void> {
  if (browserName === "chrome" && !manifest.background?.service_worker) {
    throw new Error(`${browserName}: expected background.service_worker`);
  }
+  if (browserName === "chrome" && manifest.update_url) {
+    throw new Error(`${browserName}: update_url must not be set`);
+  }
  if (
    browserName === "firefox" &&
    (!Array.isArray(manifest.background?.scripts) ||
@ -614,6 +682,15 @@ async function verifyOne(browserName: "chrome" | "firefox"): Promise<void> {
  ) {
    throw new Error(`${browserName}: expected background.scripts[]`);
  }
+  if (
+    browserName === "firefox" &&
+    manifest.browser_specific_settings?.gecko?.update_url !==
+      FIREFOX_UPDATES_MANIFEST_URL
+  ) {
+    throw new Error(
+      `${browserName}: expected browser_specific_settings.gecko.update_url to be ${FIREFOX_UPDATES_MANIFEST_URL}, got ${manifest.browser_specific_settings?.gecko?.update_url}`,
+    );
+  }

  assertValidPatterns(
    "host_permissions",
@ -726,6 +803,15 @@ export async function verifyExtensionOutputs(
  }
  if (target === "all" || target === "firefox") {
    await verifyOne("firefox");
+    const firefoxUpdatesManifestPath = path.join(
+      outBase,
+      FIREFOX_UPDATES_MANIFEST_FILE,
+    );
+    if (!(await exists(firefoxUpdatesManifestPath))) {
+      throw new Error(
+        `firefox: missing updates manifest at ${firefoxUpdatesManifestPath}`,
+      );
+    }
  }
  console.log("\nExtension verification complete.");
 }
@ -739,12 +825,16 @@ export async function finalizeExtensionBuildArtifacts(
  const shouldBuildFirefox = target === "all" || target === "firefox";

  await renameContentCss();
+  if (shouldBuildChrome) {
+    await fs.rm(path.join(outBase, CHROME_UPDATES_MANIFEST_FILE), { force: true });
+  }

  const version = headers.version || "0.0.0";
  let outChrome: string | null = null;
  let chromeCrx: string | null = null;
  let outFirefox: string | null = null;
  let firefoxXpi: string | null = null;
+  let firefoxUpdatesManifestPath: string | null = null;

  if (shouldBuildChrome) {
    outChrome = path.join(outBase, "chrome");
@ -760,7 +850,8 @@ export async function finalizeExtensionBuildArtifacts(

    const chromeZip = path.join(outBase, `vot-extension-chrome-${version}.zip`);
    await fs.rm(chromeZip, { force: true });
-    chromeCrx = await maybeBuildCrx({ sourceDir: outChrome, version });
+    const chromeBuildResult = await maybeBuildCrx({ sourceDir: outChrome, version });
+    chromeCrx = chromeBuildResult.crxPath;
  }

  if (shouldBuildFirefox) {
@ -777,6 +868,10 @@ export async function finalizeExtensionBuildArtifacts(

    firefoxXpi = path.join(outBase, `vot-extension-firefox-${version}.xpi`);
    await zipDir(outFirefox, firefoxXpi);
+    firefoxUpdatesManifestPath = await writeFirefoxUpdatesManifest({
+      version,
+      addonId: getFirefoxAddonId(),
+    });
  }

  await verifyExtensionOutputs(target);
@ -789,6 +884,7 @@ export async function finalizeExtensionBuildArtifacts(
  if (outFirefox) {
    console.log(`- Firefox: ${outFirefox}`);
    console.log(`  - Package: ${firefoxXpi}`);
+    console.log(`  - Updates: ${firefoxUpdatesManifestPath}`);
  }
 }