Feature Request: Internationalization (i18n) support for Claude Code UI

Summary

Please add internationalization (i18n) support for the Claude Code TUI so that the UI language respects the language setting in settings.json.

Current Behavior

The language setting (e.g., "japanese", "spanish") successfully makes Claude respond in the specified language, but the application UI itself remains entirely in English:

• Startup screen and welcome messages
• Menus and prompts (e.g., "What would you like to do?")
• Slash command descriptions
• All other UI text elements

Expected Behavior

When a non-English language is configured in settings.json, the UI text should be displayed in that language as well.

Use Case

Non-English speakers experience a disconnect between Claude's localized responses and the English-only UI. Proper i18n support would make Claude Code accessible to a much wider global audience.

Suggested Implementation

• Introduce a UI locale layer that reads the existing language setting
• Externalize all UI strings into locale files
• Ship translations for major languages alongside the application

🤖 Generated with Claude Code