Wengz notifications and locale

Prerequisites

• docs/ADVANCED_TECHNICAL.md § Internationalization + recipient notify locale
• docs/ADVANCED_BUSINESS.md § Notifications
• Code: src/lib/notifications/index.ts, src/lib/user-locale.ts, src/lib/error-handler.ts

Rules

1. Recipient wins — Single-user notify* helpers must call localeForUser(userId) / getPreferredLocaleForUser. Never pass staff ctx.locale as the client/provider language.
2. Staff fan-out — notifyStaffByRoles builds once per locale group from each admin’s preferredLocale.
3. Account emails by address — sendAccountApprovedEmail / Rejected resolve locale via email → user row.
4. UI toasts — Client components: useTranslations + showError/showSuccess from @/lib/error-handler with t.
5. Both languages — New notifications.* / errors.* keys in messages/en.json and messages/ar.json.
6. Cron dedupe — Stable Notification.type (e.g. subscription_expiring), not English title strings.
7. SSE — Prefer sseI18n keys when the client can re-translate; still persist a sensible title/message for the feed.

Adding a notification

1. Add translation keys (en + ar).
2. Add email template helper in src/lib/notifications/email.ts if email is needed.
3. Export notifyX that resolves recipient locale first.
4. Call from router/lib/cron; do not inline HTML in routers.
5. Cover staff vs client/provider audience correctly (roles).

Anti-patterns

• Using ctx.locale for “the other party” on approve/reject/status.
• Deduping cron notifies by translated title.
• Hardcoding English-only admin emails.