diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1872eb0..cc077ca 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,16 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ## [Unreleased]
 
+## [3.5.12] - 2026-05-11
+
+### Fixed
+- Background SW removed a dead chrome.storage.local self-healing path for the YouTube InnerTube client version. The hydration block read `sb_yt_client_version` on every SW wake but **no code anywhere ever wrote that key** — the comment claimed the maintenance alarm refreshed it, but the alarm only sends `version-check` against GitHub. The runtime override never triggered; `_BG_YT_CLIENT_VERSION` was effectively a const all along. Replaced the let + hydration block with a plain const + comment explaining the manual-bump workflow (in sync with `src/lib/constants.js` + `src/shared/constants.json` via `check-bg-sync.js`). Also removes the fire-and-forget storage race on every SW wake.
+- `FETCH_URL` proxy handler now routes through `fetchWithRetry` instead of raw `fetch`. Previously a transient YouTube/InnerTube 5xx propagated straight to the content script while `GOOGLE_TRANSLATE_BATCH` got the retry contract — inconsistency the v3.5.8 fix was supposed to eliminate.
+- `handleVersionCheck` (GitHub API call) likewise routes through `fetchWithRetry`. Anonymous GitHub quota is 60/h per IP; with users converging on residential ranges, 403s are common, and the previous code silently dropped them with a single attempt. The 4xx fail-fast contract still prevents pointless retries on 403/404.
+
+### Changed
+- Added `https://api.github.com/*` to `host_permissions` in `manifest.json`. SW `fetch` to undeclared origins works in MV3 but CWS reviewers flag undeclared hostnames; explicit declaration matches what the code actually does.
+
 ## [3.5.11] - 2026-05-07
 
 ### Security / Hardening
diff --git a/README.md b/README.md
index 0758474..21fa2cb 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 <img src="assets/icons/icon128.png" alt="SkillBridge" width="90" />
 
-# SkillBridge for Anthropic Academy <!-- VERSION_START -->v3.5.11<!-- VERSION_END -->
+# SkillBridge for Anthropic Academy <!-- VERSION_START -->v3.5.12<!-- VERSION_END -->
 
 > Available in multiple languages at the [project landing page](https://heznpc.github.io/skillBridge/).
 
diff --git a/docs/index.html b/docs/index.html
index e72f06b..5f82dea 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -6,7 +6,7 @@
   <title>SkillBridge — AI Course Translator for <!-- LANG_COUNT_START -->32+<!-- LANG_COUNT_END --> Languages</title>
   <meta name="description" content="Free Chrome extension to translate Anthropic Academy courses into <!-- LANG_COUNT_START -->32+<!-- LANG_COUNT_END --> languages with AI-powered tutoring. No API keys needed.">
   <meta property="og:title" content="SkillBridge — AI Course Translator">
-  <meta property="og:description" content="Learn Anthropic's free AI courses in your language. Powered by <!-- VERSION_START -->v3.5.11<!-- VERSION_END -->.">
+  <meta property="og:description" content="Learn Anthropic's free AI courses in your language. Powered by <!-- VERSION_START -->v3.5.12<!-- VERSION_END -->.">
   <meta property="og:type" content="website">
   <style>
     * { margin: 0; padding: 0; box-sizing: border-box; }
@@ -255,7 +255,7 @@
 <body>
   <section class="hero">
     <div class="container">
-      <div class="hero-badge"><!-- VERSION_START -->v3.5.11<!-- VERSION_END --> &middot; Open Source &middot; Free &middot; No API Key</div>
+      <div class="hero-badge"><!-- VERSION_START -->v3.5.12<!-- VERSION_END --> &middot; Open Source &middot; Free &middot; No API Key</div>
       <h1>Learn Anthropic Courses<br>In Your Language</h1>
       <p>A Chrome extension that translates Anthropic Academy courses into <!-- LANG_COUNT_START -->32+<!-- LANG_COUNT_END --> languages with an AI-powered learning assistant.</p>
       <p style="font-size:13px;opacity:0.85;margin-top:-16px;">Not affiliated with, endorsed by, or sponsored by Anthropic.</p>
diff --git a/manifest.json b/manifest.json
index 859957d..e2fcb25 100644
--- a/manifest.json
+++ b/manifest.json
@@ -2,7 +2,7 @@
   "manifest_version": 3,
   "name": "__MSG_extName__",
   "description": "__MSG_extDescription__",
-  "version": "3.5.11",
+  "version": "3.5.12",
   "minimum_chrome_version": "120",
   "author": "SkillBridge Contributors",
   "homepage_url": "https://github.com/heznpc/skillbridge",
@@ -14,7 +14,8 @@
   "host_permissions": [
     "https://*.skilljar.com/*",
     "https://*.youtube.com/*",
-    "https://translate.googleapis.com/*"
+    "https://translate.googleapis.com/*",
+    "https://api.github.com/*"
   ],
   "action": {
     "default_popup": "src/popup/popup.html",
diff --git a/package.json b/package.json
index 67a16a6..5ba2fd2 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "skillbridge",
-  "version": "3.5.11",
+  "version": "3.5.12",
   "private": true,
   "scripts": {
     "test": "jest --verbose",
diff --git a/scripts/check-bg-sync.js b/scripts/check-bg-sync.js
index 3cb2a9a..4d6b275 100644
--- a/scripts/check-bg-sync.js
+++ b/scripts/check-bg-sync.js
@@ -82,15 +82,15 @@ if (!bgMapMatch) {
   }
 }
 
-// Extract _BG_YT_CLIENT_VERSION_DEFAULT fallback — this is the inline default
-// that is always present; _BG_YT_CLIENT_VERSION itself is a `let` that gets
-// hydrated from chrome.storage.local at runtime (see #78).
-const bgVerMatch = bgSrc.match(/(?:const|let)\s+_BG_YT_CLIENT_VERSION_DEFAULT\s*=\s*'([^']+)'/);
+// Extract _BG_YT_CLIENT_VERSION (since v3.5.12 this is a plain const — the
+// previous storage-hydrated `let _BG_YT_CLIENT_VERSION_DEFAULT` was removed
+// because no code ever wrote the storage key the override depended on).
+const bgVerMatch = bgSrc.match(/const\s+_BG_YT_CLIENT_VERSION\s*=\s*'([^']+)'/);
 if (!bgVerMatch) {
-  fail('Could not find _BG_YT_CLIENT_VERSION_DEFAULT in background.js');
+  fail('Could not find _BG_YT_CLIENT_VERSION in background.js');
 } else if (bgVerMatch[1] !== jsonVersion) {
   fail(
-    `_BG_YT_CLIENT_VERSION_DEFAULT fallback in background.js differs from constants.json\n  background.js:  ${bgVerMatch[1]}\n  constants.json: ${jsonVersion}`,
+    `_BG_YT_CLIENT_VERSION in background.js differs from constants.json\n  background.js:  ${bgVerMatch[1]}\n  constants.json: ${jsonVersion}`,
   );
 }
 
diff --git a/src/background/background.js b/src/background/background.js
index 4e067fa..211c0d7 100644
--- a/src/background/background.js
+++ b/src/background/background.js
@@ -11,42 +11,10 @@
 // Shared constants — kept in sync with src/shared/constants.json via scripts/check-bg-sync.js
 const _BG_GT_LANG_MAP = { 'zh-CN': 'zh-CN', 'zh-TW': 'zh-TW', 'pt-BR': 'pt' };
 
-// YouTube's internal client version is bumped every few weeks. Storing the
-// "default" inline as a fallback and overriding it from chrome.storage.local
-// (refreshed by the maintenance alarm) means a stale build keeps working
-// until the next 24h alarm tick rather than dying immediately.
-const _BG_YT_CLIENT_VERSION_DEFAULT = '2.20260415.01.00';
-let _BG_YT_CLIENT_VERSION = _BG_YT_CLIENT_VERSION_DEFAULT;
-
-const _YT_VERSION_STORAGE_KEY = 'sb_yt_client_version';
-
-// Hydrate the runtime override from storage on service worker start.
-// Wrapped defensively because tests stub `chrome` with only the surfaces
-// they exercise — production always has chrome.storage.local available.
-if (
-  typeof chrome !== 'undefined' &&
-  chrome.storage &&
-  chrome.storage.local &&
-  typeof chrome.storage.local.get === 'function'
-) {
-  try {
-    const result = chrome.storage.local.get(_YT_VERSION_STORAGE_KEY);
-    if (result && typeof result.then === 'function') {
-      result
-        .then((stored) => {
-          const v = stored && stored[_YT_VERSION_STORAGE_KEY];
-          if (typeof v === 'string' && /^\d+\.\d+\.\d+\.\d+$/.test(v)) {
-            _BG_YT_CLIENT_VERSION = v;
-          }
-        })
-        .catch(() => {
-          /* non-fatal */
-        });
-    }
-  } catch {
-    /* test stub may throw — non-fatal */
-  }
-}
+// YouTube's internal client version. Bumped manually when InnerTube rejects
+// our value (observed every few weeks); kept in sync with the same constant
+// in src/lib/constants.js + src/shared/constants.json via check-bg-sync.js.
+const _BG_YT_CLIENT_VERSION = '2.20260415.01.00';
 
 function gtLangCode(lang) {
   return _BG_GT_LANG_MAP[lang] || lang;
@@ -181,13 +149,13 @@ async function handleVersionCheck() {
     const manifest = chrome.runtime.getManifest();
     const localVersion = manifest.version;
 
-    const resp = await fetch(`https://api.github.com/repos/${_GITHUB_REPO}/releases/latest`, {
+    // Anonymous GitHub API quota is 60/h per IP — with hundreds of users on
+    // the same residential ranges, 403s are common. fetchWithRetry's 4xx
+    // fail-fast bails immediately on 403/404 (no point retrying without auth)
+    // and backs off transient 5xx.
+    const resp = await fetchWithRetry(`https://api.github.com/repos/${_GITHUB_REPO}/releases/latest`, {
       headers: { Accept: 'application/vnd.github.v3+json' },
     });
-    if (!resp.ok) {
-      console.warn(`[SkillBridge] Version check: GitHub API returned ${resp.status}`);
-      return;
-    }
     const release = await resp.json();
     const remoteVersion = (release.tag_name || '').replace(/^v/, '');
 
@@ -272,14 +240,13 @@ chrome.runtime.onMessage.addListener((msg, sender, sendResponse) => {
       }
     }
     fetchOpts.headers = headers;
-    fetch(msg.url, fetchOpts)
-      .then((resp) => {
-        if (!resp.ok) throw new Error(`HTTP ${resp.status}`);
-        return resp.text();
-      })
+    // Route through fetchWithRetry so 5xx/429s back off, 4xx fails fast,
+    // and the abuse-pattern contract is consistent with the GT path.
+    fetchWithRetry(msg.url, fetchOpts)
+      .then((resp) => resp.text())
       .then((text) => sendResponse({ ok: true, data: text }))
       .catch((err) => {
-        console.error(`[SkillBridge BG] Error: ${err.message}`);
+        console.error(`[SkillBridge BG] FETCH_URL error: ${err.message}`);
         sendResponse({ ok: false, error: err.message });
       });
     return true;
diff --git a/src/data/de.json b/src/data/de.json
index 851b501..cbcd920 100644
--- a/src/data/de.json
+++ b/src/data/de.json
@@ -2,7 +2,7 @@
   "_meta": {
     "lang": "de",
     "langName": "Deutsch",
-    "version": "3.5.11",
+    "version": "3.5.12",
     "lastUpdated": "2026-04-02"
   },
   "ui": {
diff --git a/src/data/es.json b/src/data/es.json
index 17fb74d..60cad62 100644
--- a/src/data/es.json
+++ b/src/data/es.json
@@ -2,7 +2,7 @@
   "_meta": {
     "lang": "es",
     "langName": "Español",
-    "version": "3.5.11",
+    "version": "3.5.12",
     "lastUpdated": "2026-04-02"
   },
   "ui": {
diff --git a/src/data/fr.json b/src/data/fr.json
index f750b9a..6e647c3 100644
--- a/src/data/fr.json
+++ b/src/data/fr.json
@@ -2,7 +2,7 @@
   "_meta": {
     "lang": "fr",
     "langName": "Français",
-    "version": "3.5.11",
+    "version": "3.5.12",
     "lastUpdated": "2026-04-02"
   },
   "ui": {
diff --git a/src/data/ja.json b/src/data/ja.json
index 4c7677b..149d275 100644
--- a/src/data/ja.json
+++ b/src/data/ja.json
@@ -2,7 +2,7 @@
   "_meta": {
     "lang": "ja",
     "langName": "日本語",
-    "version": "3.5.11",
+    "version": "3.5.12",
     "lastUpdated": "2026-04-02"
   },
   "ui": {
diff --git a/src/data/ko.json b/src/data/ko.json
index a7f8309..5ce966a 100644
--- a/src/data/ko.json
+++ b/src/data/ko.json
@@ -2,7 +2,7 @@
   "_meta": {
     "lang": "ko",
     "langName": "한국어",
-    "version": "3.5.11",
+    "version": "3.5.12",
     "lastUpdated": "2026-04-02"
   },
   "ui": {
diff --git a/src/data/pt-BR.json b/src/data/pt-BR.json
index 0d73fd1..b64d04c 100644
--- a/src/data/pt-BR.json
+++ b/src/data/pt-BR.json
@@ -2,7 +2,7 @@
   "_meta": {
     "lang": "pt-BR",
     "langName": "Português (BR)",
-    "version": "3.5.11",
+    "version": "3.5.12",
     "lastUpdated": "2026-04-02"
   },
   "ui": {
diff --git a/src/data/ru.json b/src/data/ru.json
index 722e5b7..35bdf69 100644
--- a/src/data/ru.json
+++ b/src/data/ru.json
@@ -2,7 +2,7 @@
   "_meta": {
     "lang": "ru",
     "langName": "Русский",
-    "version": "3.5.11",
+    "version": "3.5.12",
     "lastUpdated": "2026-04-02"
   },
   "ui": {
diff --git a/src/data/vi.json b/src/data/vi.json
index 4252acc..869bef3 100644
--- a/src/data/vi.json
+++ b/src/data/vi.json
@@ -2,7 +2,7 @@
   "_meta": {
     "lang": "vi",
     "langName": "Tiếng Việt",
-    "version": "3.5.11",
+    "version": "3.5.12",
     "lastUpdated": "2026-04-02"
   },
   "ui": {
diff --git a/src/data/zh-CN.json b/src/data/zh-CN.json
index 16cec44..185b7b9 100644
--- a/src/data/zh-CN.json
+++ b/src/data/zh-CN.json
@@ -2,7 +2,7 @@
   "_meta": {
     "lang": "zh-CN",
     "langName": "简体中文",
-    "version": "3.5.11",
+    "version": "3.5.12",
     "lastUpdated": "2026-04-02"
   },
   "ui": {
diff --git a/src/data/zh-TW.json b/src/data/zh-TW.json
index 0f466d4..f893f5e 100644
--- a/src/data/zh-TW.json
+++ b/src/data/zh-TW.json
@@ -2,7 +2,7 @@
   "_meta": {
     "lang": "zh-TW",
     "langName": "中文(繁體)",
-    "version": "3.5.11",
+    "version": "3.5.12",
     "lastUpdated": "2026-04-02"
   },
   "ui": {
