Auto-detect LLM output language from system locale on first startup

2026-04-28 11:41:04 +00:00 · 2025-12-13 15:19:55 +01:00 · 2025-12-13 15:19:55 +01:00 · 4d9f25e9fe
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+# Language Settings
+
+Qwen Code supports multiple languages for both the user interface and LLM responses.
+
+## Overview
+
+Two separate language settings control different aspects of Qwen Code:
+
+| Setting            | What it controls                                   | Where stored                 |
+| ------------------ | -------------------------------------------------- | ---------------------------- |
+| `/language ui`     | Terminal UI text (menus, system messages, prompts) | `~/.qwen/settings.json`      |
+| `/language output` | Language the AI responds in                        | `~/.qwen/output-language.md` |
+
+## UI Language
+
+### Setting the UI Language
+
+Use the `/language ui` command:
+
+```bash
+/language ui zh-CN    # Chinese
+/language ui en-US    # English
+/language ui ru-RU    # Russian
+/language ui de-DE    # German
+```
+
+Aliases are also supported:
+
+```bash
+/language ui zh       # Chinese
+/language ui en       # English
+/language ui ru       # Russian
+/language ui de       # German
+```
+
+### Auto-detection
+
+On first startup, Qwen Code detects your system locale and sets the UI language automatically.
+
+Detection priority:
+
+1. `QWEN_CODE_LANG` environment variable
+2. `LANG` environment variable
+3. System locale via JavaScript Intl API
+4. Default: English
+
+## LLM Output Language
+
+The LLM output language controls what language the AI assistant responds in, regardless of what language you type your questions in.
+
+### How It Works
+
+The LLM output language is controlled by a rule file at `~/.qwen/output-language.md`. This file is automatically included in the LLM's context during startup, instructing it to respond in the specified language.
+
+### Auto-detection
+
+On first startup, if no `output-language.md` file exists, Qwen Code automatically creates one based on your system locale. For example:
+
+- System locale `zh` creates a rule for Chinese responses
+- System locale `en` creates a rule for English responses
+- System locale `ru` creates a rule for Russian responses
+- System locale `de` creates a rule for German responses
+
+### Manual Setting
+
+Use `/language output <language>` to change:
+
+```bash
+/language output Chinese
+/language output English
+/language output Japanese
+/language output German
+```
+
+Any language name works. The LLM will be instructed to respond in that language.
+
+### File Location
+
+```
+~/.qwen/output-language.md
+```
+
+## Configuration
+
+### Via Settings Dialog
+
+1. Run `/settings`
+2. Find "Language" under General
+3. Select your preferred UI language
+
+### Via Environment Variable
+
+```bash
+export QWEN_CODE_LANG=zh
+```
+
+This sets both the UI language detection and the LLM output language detection on first startup.
+
+## Custom Language Packs
+
+For UI translations, you can create custom language packs in `~/.qwen/locales/`:
+
+- Example: `~/.qwen/locales/es.js` for Spanish
+- Example: `~/.qwen/locales/fr.js` for French
+
+User directory takes precedence over built-in translations.
+
+### Language Pack Format
+
+```javascript
+// ~/.qwen/locales/es.js
+export default {
+  Hello: 'Hola',
+  Settings: 'Configuracion',
+  // ... more translations
+};
+```
+
+## Related Commands
+
+- `/language` - Show current language settings
+- `/language ui [lang]` - Set UI language
+- `/language output <language>` - Set LLM output language
+- `/settings` - Open settings dialog