fix(i18n): standardize UI-language promise on 12 premium + close the stale gate

POSITIONING.md

@@ -24,7 +24,7 @@ REDACTED — internal only, never on any public surface.)
   note the earlier "Europe-led / Korean ~0 / US minor" read was **wrong**: the US
   is a **top-2 market** and Korea is mid-pack (~#6), not negligible. Default
   framing is global / English-default — a single English CWS listing (ko/ja store
-  listings were dropped; the in-product UI stays localized in 11 languages). If a
+  listings were dropped; the in-product UI stays localized in 12 premium languages). If a
   localized listing is ever revisited, Japanese and Korean (each ~#6 by
   language/region) are the first candidates — not a priority now.
 - **Why Italy is #1 — a verified organic-referral mechanism** (web-verified
@@ -328,7 +328,7 @@ Once #1–#2 are cleared:
 - If a PR meaningfully improves the AI tutor's contextual awareness of
   the current lesson, default ship.
 - If a PR ships a new feature without updating the relevant `_LABELS`
-  dict to cover all 11 premium languages, default reject (we don't ship
+  dict to cover all 12 premium languages, default reject (we don't ship
   English-only UI in a "translate this for non-English speakers"
   product).
 - If two PRs conflict and one has measurable Korean-user impact, the

TODO.md

@@ -95,8 +95,9 @@ narrowed.
 - ~~**CWS listing — multilingual translations.**~~ Dropped (v3.5.39): the CWS
   listing is English-only. Every locale falls back to EN, and hand-maintaining
   parallel localized listings caused drift (#158) for marginal per-market gain.
-  The extension UI stays localized in 11 languages; only the store metadata is
-  EN-only.
+  The in-product UI stays localized in 12 premium languages (and the browser-facing
+  extension name/description in the 33 `_locales/` Chrome-metadata locales); only the
+  Chrome Web Store *listing copy* (screenshots / long description) is EN-only.
 - [ ] **YouTube `_BG_YT_CLIENT_VERSION` auto-bump GH Action.** Currently
   manual every few weeks (see comment in `src/background/background.js`).
   Cron workflow that pings InnerTube and opens a PR when stale. Same

docs/TELEMETRY_DESIGN.md

@@ -178,7 +178,7 @@ Approximate scope when this is approved:
 2. `src/background/background.js`: wire `chrome.runtime.onInstalled` + `chrome.runtime.setUninstallURL`, hook the global `self.addEventListener('error', ...)` for service worker errors.
 3. `src/content/content.js`: hook `window.addEventListener('error', ...)` and `window.addEventListener('unhandledrejection', ...)` — gated behind opt-in flag.
 4. `src/popup/popup.html` + `popup.js`: two new toggles, "Delete my data" button, "What we collect" link to privacy policy.
-5. `_locales/*/messages.json`: 11 premium-language strings for the new popup copy. **POSITIONING operating-principle gate**: "default reject" for new UI without all-11-language coverage.
+5. `_locales/*/messages.json`: new popup-copy strings (browser-metadata layer, all 33 `_locales/`). **POSITIONING operating-principle gate**: "default reject" for new in-product UI without all-12-premium-language coverage in the `src/lib/constants.js` `_LABELS` dicts.
 6. `docs/privacy.html`: the rewrite above.
 7. `tests/lib/telemetry.test.js`: ~10 unit tests covering payload sanitization, regex stripping, slug-hash determinism, opt-out clears `client_id`.
 8. `tests/e2e/telemetry.spec.js`: 1 scenario — toggle on, trigger an error, intercept the POST, assert payload shape and excluded-fields.

scripts/check-i18n-keys.js

@@ -99,6 +99,12 @@ function matchExports(src) {
 let dicts;
 try {
   const names = matchExports(constantsSrc);
+  // matchExports targets the *_LABELS/UI/QUESTIONS/... dicts, but we also need
+  // PREMIUM_LANGUAGE_CODES to derive the expected-language set (below) from the
+  // source of truth instead of a hand-maintained list that goes stale.
+  if (/\bconst PREMIUM_LANGUAGE_CODES\b/.test(constantsSrc) && !names.includes('PREMIUM_LANGUAGE_CODES')) {
+    names.push('PREMIUM_LANGUAGE_CODES');
+  }
   // Both source files reference `window` at the top; provide a stub so the
   // top-level `if (typeof window !== 'undefined')` guards don't trip.
   const runner = new Function('window', `${selectorsSrc}\n${constantsSrc}\nreturn { ${names.join(', ')} };`);
@@ -109,7 +115,16 @@ try {
   process.exit(errors > 0 ? 1 : 0);
 }
 
-const expectedLangs = new Set(['en', 'ko', 'ja', 'zh-CN', 'zh-TW', 'es', 'fr', 'de', 'pt-BR', 'ru', 'vi']);
+// English + every premium-dictionary language. Derived from PREMIUM_LANGUAGE_CODES
+// so it self-updates when a premium locale is added — the previous hand-coded list
+// was en+10 and silently missed the it/id UI labels. Falls back to the full 12 if
+// the constant can't be loaded.
+const PREMIUM_FALLBACK = ['ko', 'ja', 'zh-CN', 'zh-TW', 'es', 'fr', 'it', 'de', 'pt-BR', 'ru', 'vi', 'id'];
+const premiumCodes =
+  Array.isArray(dicts.PREMIUM_LANGUAGE_CODES) && dicts.PREMIUM_LANGUAGE_CODES.length
+    ? dicts.PREMIUM_LANGUAGE_CODES
+    : PREMIUM_FALLBACK;
+const expectedLangs = new Set(['en', ...premiumCodes]);
 
 /**
  * Validate a flat lang map: { en: 'x', ko: 'x', ... }.

src/lib/constants.js

@@ -364,10 +364,12 @@ const BANNER_UI = {
   'zh-TW': { prompt: '將此頁面翻譯為', confirm: '翻譯', dismiss: '關閉' },
   es: { prompt: '¿Traducir esta página a', confirm: 'Traducir', dismiss: 'Cerrar' },
   fr: { prompt: 'Traduire cette page en', confirm: 'Traduire', dismiss: 'Fermer' },
+  it: { prompt: 'Traduci questa pagina in', confirm: 'Traduci', dismiss: 'Chiudi' },
   de: { prompt: 'Diese Seite übersetzen auf', confirm: 'Übersetzen', dismiss: 'Schließen' },
   'pt-BR': { prompt: 'Traduzir esta página para', confirm: 'Traduzir', dismiss: 'Fechar' },
   ru: { prompt: 'Перевести эту страницу на', confirm: 'Перевести', dismiss: 'Закрыть' },
   vi: { prompt: 'Dịch trang này sang', confirm: 'Dịch', dismiss: 'Đóng' },
+  id: { prompt: 'Terjemahkan halaman ini ke', confirm: 'Terjemahkan', dismiss: 'Tutup' },
 };
 
 // Onboarding banner for ALL first-time visitors (including English speakers)
@@ -500,6 +502,12 @@ const EXAMPLE_QUESTIONS = {
     'Fammi un quiz su questa lezione',
     'Riassumi questa lezione',
   ],
+  id: [
+    'Jelaskan konsep ini secara sederhana',
+    'Apa poin-poin pentingnya?',
+    'Beri saya kuis tentang pelajaran ini',
+    'Ringkas pelajaran ini',
+  ],
 };
 
 const DASHBOARD_LABELS = {