---
name: locale-ui-patterns
description: Use when creating or modifying OpenChamber UI text, labels, buttons, placeholders, aria labels, empty states, toasts, dialogs, settings copy, navigation labels, or any user-facing strings.
---

# Locale UI Patterns

## Core Rule

User-facing UI text must go through `@/lib/i18n`; do not hardcode English strings in components.

## Translate everything immediately (no English placeholders)

Every key you add to a non-English dictionary MUST contain a real translation in that language — never the English source string as a stand-in. There is NO "leave it in English for now" convention in this project; if an agent told you there was, it was wrong. Copying the English value into `es.ts`/`fr.ts`/`ko.ts`/`pl.ts`/`pt-BR.ts`/`uk.ts`/`zh-CN.ts`/`zh-TW.ts` is a defect, not a deferral. The app ships every locale at once, so an untranslated key is a visible bug for those users.

If you genuinely cannot translate a language, say so explicitly to the user instead of silently pasting English. Do not invent a fallback policy.

## Required Flow

1. Add or reuse a key in `packages/ui/src/lib/i18n/messages/en.ts`.
2. Add the same key — fully translated, not the English text — to every non-English dictionary in `packages/ui/src/lib/i18n/messages/`.
3. In components, call `const { t } = useI18n()` from `@/lib/i18n` and render `t('key')`.
4. For locale names or language picker labels, use `label(locale)` from `useI18n()`.
5. Keep locale state in `packages/ui/src/lib/i18n/*`; do not add locale fields to broad stores like `useUIStore`.
6. Do not remount the app to update language. Components must re-render through `useI18n()`.

## Component Usage Rules

- Import from `@/lib/i18n`, not deep files.
- Keep `t(...)` calls inside React render/hook scope so locale changes re-render text.
- Do not resolve translated text at module scope.
- For static option arrays, store `labelKey` / `descriptionKey`; resolve with `t(...)` inside the component.
- For non-React helpers, pass translated strings in from the component or pass `t` explicitly.

## Key Style

Use stable semantic keys, not English text as keys.

Keys should describe location + UI role + meaning. They should not encode current copy wording.

Use existing nearby naming when extending a surface. If no nearby pattern exists, choose a short path that mirrors the UI ownership.

Namespaces like `layout.*`, `settings.*`, `chat.*`, `git.*`, `session.*`, `toast.*`, and `dialog.*` are examples, not a fixed exhaustive list.

Good:
```ts
'settings.appearance.language.label': 'Language'
'layout.mainTab.chat': 'Chat'
'chat.input.placeholder': 'Ask OpenChamber...'
```

Bad:
```ts
'Language': 'Language'
'chatLabel': 'Chat'
'askOpenChamberDotDotDot': 'Ask OpenChamber...'
```

Avoid overly generic keys unless the text is truly global and context-independent. Prefer specific keys when button meaning can vary by surface.

## Parameters

Use `{name}` placeholders for dynamic values.

```ts
'toast.language.changed': 'Language changed to {language}'
```

```tsx
t('toast.language.changed', { language: label(locale) })
```

Do not pass grammar fragments as params. Never use params like `{suffix}`, `{plural}`, `{article}`, `{prefix}`, `{dateSuffix}`, or pieces of words/sentences.

Bad:
```tsx
t('dialog.delete.description', { count, suffix: count === 1 ? '' : 's' })
```

Good:
```tsx
count === 1
  ? t('dialog.delete.descriptionSingle', { count })
  : t('dialog.delete.descriptionPlural', { count })
```

Plural/count-dependent text must use separate complete-message keys unless all supported locales can use one identical complete sentence. Placeholders are only for real values (`{count}`, `{name}`, `{path}`), not grammar.

Optional clauses must also be complete-message keys. Do not build a sentence by injecting a translated phrase into another translated sentence.

Bad:
```tsx
t('dialog.delete.description', {
  dateLabel: date ? t('dialog.delete.dateSuffix', { date }) : '',
})
```

Good:
```tsx
date
  ? t('dialog.delete.descriptionWithDate', { count, date })
  : t('dialog.delete.description', { count })
```

## Translation Boundary

Translate visible text, placeholders, tooltips, dialogs, toasts, empty/error/loading states, and user-facing `aria-label`, `title`, and `alt` text.

Keep these literal:

- Product names: `OpenChamber`, `OpenCode`, `GitHub`
- Protocol/tool acronyms: `MCP`, `SSE`, `WebSocket`, `API`
- Model/provider names
- File paths, command names, environment variables
- User/generated content

## Completion Criteria

- No new hardcoded user-facing English in changed UI files.
- Every new key exists in all dictionaries with a real translation.
- All translated values are resolved inside a reactive render/hook boundary.
- No locale state added to broad/shared stores.
- No full app remount for locale changes.
- Locale switch preserves current UI state.