internationalization

# Internationalization ## Rule **Opt-in only.** Do not add i18n catalogs, `LanguagePicker`, locale init scripts, or `AppProviders i18n={{...}}` unless the user explicitly asks for internationalization / localization / multiple languages. This starter ships **English-only inline copy**. For normal UI text edits, change the string in the component and stop — do not create `app/i18n/`. When the user does request i18n, then: visible UI copy belongs in the app's i18n catalog, not inline in components. Update the English source catalog first, update existing locale catalogs, and run the i18n guard. ## Catalogs When enabling i18n, use `app/i18n/`: - `en-US.ts` is the canonical source tree and fallback. - Other locale files keep the same non-plural keys and the same placeholders. - `index.ts` exports an `AgentNativeI18nCatalog` with English bundled and non-English catalogs loaded by dynamic import. Use BCP-47 filenames from the supported set: `en-US`, `zh-CN`, `zh-TW`, `es-ES`, `fr-FR`, `de-DE`, `ja-JP`, `ko-KR`, `pt-BR`, `hi-IN`, `ar-SA`. ## Verification Run: ```bash pnpm guard:i18n-catalogs ``` For broader changes, also run the affected tests and a single `pnpm typecheck` at the end of the batch.