I18n Expert

Overview

Deliver a complete i18n setup + audit pass: configure the i18n framework, replace user-facing strings with keys, ensure locale parity, and validate pluralization/formatting for en-US and zh-CN.

Core Capabilities

• Library selection and setup (React, Next.js, Vue).

• Key architecture and locale file organization.

• Translation generation and quality strategy (AI, professional, manual).

• Routing and language detection/switching.

• SEO and metadata localization (when applicable).

• RTL support (only if RTL locales are in scope).

Scope Inputs (ask if unclear)

• Framework and routing style.

• Existing i18n state (none, partial, legacy).

• Target locales (default: en-US + zh-CN).

• Translation quality needs (AI vs professional vs manual).

• Locale formats in use (JSON, YAML, PO, XLIFF).

• Formality/cultural requirements (if any).

Workflow (Audit -> Fix -> Validate)

• Confirm scope and locale targets

• Identify the i18n framework and locale locations.

• Confirm locales; default to en-US + zh-CN when specified.

• Setup i18n baseline (if missing)

• Choose a framework-appropriate library (e.g., React: react-i18next; Next.js: next-intl; Vue: vue-i18n).

• Install packages and create the i18n entry/config file.

• Wire the provider at the app root and load locale resources.

• Add a language switcher and persistence (route/param/localStorage) as appropriate.

• Establish locale file layout and key namespaces.

• If routing is locale-aware, define the locale segment strategy early (subpath, subdomain, query param).

• If metadata is user-facing, include translation for titles/descriptions.

• Audit key usage and locale parity

• Run: python scripts/i18n_audit.py --src <src-root> --locale <path/to/en-US.json> --locale <path/to/zh-CN.json>

• Treat missing keys/parity gaps as blockers.

• Manually verify dynamic keys (t(var) ).

• Find raw user-facing strings

• Search: rg -n --glob '<src>//.{ts,tsx,js,jsx}' "<[^>]+>[^<{][A-Za-z][^<{]*<" rg -n --glob '<src>//*.{ts,tsx,js,jsx}' "aria-label="[^"]+"|title="[^"]+"|placeholder="[^"]+""

• Localize accessibility labels.

• Replace strings with keys

• Use t('namespace.key') for UI text.

• For plurals use t('key', { count })

• _one/_other keys.

• Use Intl/app formatters for time/date/number.

• Localize error handling (critical)

• Map error codes to localized keys; show localized UI only.

• Log raw error details only.

• Provide localized fallback for unknown codes.

• Update locale files

• Add missing keys in both locales.

• Keep placeholders consistent; avoid renames unless requested.

• Generate translations using the agreed method; preserve placeholders and plural rules.

• Validate

• Re-run the audit until missing/parity issues are zero.

• Validate JSON (e.g., python -m json.tool <file> ).

• Update tests asserting visible text.

Guardrails

• Never expose raw error.message to UI; show localized strings only.

• Do not add extra locales unless explicitly requested.

• Prefer structured namespaces (e.g., errors.* , buttons.* , workspace.* ).

• Keep translations concise and consistent.

• Some technical/brand terms should remain untranslated (e.g., product name, API, MCP, Bash).

Deliverables (expected outputs)

• i18n config/provider wiring.

• Locale files for each target language.

• Replaced UI strings with stable keys.

• Language switcher and persistence (if applicable).

• Updated tests for visible text.

Architecture Guidance (keep concise)

• Key structure: prefer nested namespaces by area (e.g., common.buttons.save , pricing.tier.pro ).

• File layout: one file per locale or per-locale namespaces; keep keys in sync across locales.

• Placeholders: preserve {name} /{{name}} exactly; validate plurals by locale rules.

• Formatting: use Intl/app helpers for date, time, number, and list formatting.

• SEO/metadata: localize titles and descriptions if the app exposes them.

• RTL: only needed for RTL locales; use logical CSS properties and test layout.

• Non-web surfaces (Electron main-process dialogs, CLI prompts, native menus) need localization too.

Performance Notes (short)

• Lazy-load locale bundles when the app supports it.

• Split large locale files by namespace.

Failure Modes (watchlist)

• Missing translations: fall back to default locale and log warnings.

• RTL layout issues: verify logical CSS and test pages.

• SEO missing: ensure alternates and metadata are localized when applicable.

Validation Checklist (short)

• No missing keys and no raw UI strings.

• Locale switching works and persists.

• Plurals and formatting verified in both locales.

• Fallback locale configured.

Resources

scripts/

• scripts/i18n_audit.py : Extracts t('key') usage and compares against locale JSON files.