Language (i18n)

proto supports both UI localization (terminal menus, system messages) and LLM output language control.

UI language

Controls the language of CLI menus, prompts, and system messages.

/language ui zh-CN    # Chinese (Simplified)
/language ui en-US    # English
/language ui de-DE    # German
/language ui ja-JP    # Japanese
/language ui ru-RU    # Russian

Short aliases also work: zh, en, de, ja, ru.

Auto-detection priority:

1. PROTO_LANG environment variable
2. LANG environment variable
3. System locale via JavaScript Intl API
4. Default: English

LLM output language

Controls what language proto’s assistant responds in, regardless of what language you write in.

/language output Chinese
/language output English
/language output Japanese

Any language name works. The preference is stored in ~/.proto/output-language.md and injected into the system prompt at session start.

[!note] Restart proto after changing the output language for the change to take effect.

View current settings

/language

Set via settings

// ~/.proto/settings.json
{
  "general": {
    "language": "zh-CN"
  }
}

Or set the environment variable before starting:

export PROTO_LANG=zh proto

Custom language packs

Override or extend built-in UI translations by placing .js files in ~/.proto/locales/:

// ~/.proto/locales/es.js
export default {
  Hello: 'Hola',
  Settings: 'Configuracion',
};

User locale files take precedence over built-in translations.