Internationalization and Localization Support for CLI Interface

[kaminuma]

Summary

Add internationalization (i18n) and localization (l10n) support for Claude Code CLI interface messages, command outputs, and help text.

Current Behavior

• All CLI interface messages are in English only
• Command outputs, error messages, and help text are hardcoded in English
• No configuration option to change display language

Requested Behavior

• Support for multiple languages in CLI interface
• Configurable language setting (e.g., via claude config set language ja)
• Localized messages for:
  • Command outputs and success/error messages
  • Help text and documentation
  • Agent creation messages
  • Progress indicators and status updates

Use Case

Many non-English speaking developers would benefit from having Claude Code interface in their native language, especially for:

• Better understanding of error messages
• Improved onboarding experience
• Enhanced productivity in local development environments

Proposed Implementation

1. Add language configuration option
2. Implement message localization system
3. Support popular languages (Japanese, Spanish, French, German, etc.)
4. Maintain English as default fallback

Related Issues

This would complement existing internationalization efforts:

• [BUG] IME input causes performance issues and duplicate conversion candidates #1547 (Japanese IME input performance issues)
• IME Composition Failure for Korean Character Input #2620 (Korean IME composition failure)
• IME Composition Input Rendering Lag for Non-Latin Scripts. #1553 (IME input rendering lag for non-Latin scripts)
• Japanese input UX improvements #1306 (Japanese input UX improvements)
• [BUG] Pasting Japanese text breaks the prompt input #678 (Japanese text pasting issues)
• [BUG] Character display corruption in Chinese text - blue "hB" artifacts appearing #2780 (Chinese text display corruption)

Together with the existing input-related issues, comprehensive internationalization support would greatly benefit the global developer community using Claude Code.

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Please let me know if a similar issue already exists - I searched through existing issues but may have missed something.

[github-actions]

Found 1 possible duplicate issue:

1. [Request]  #2415

If your issue is a duplicate, please close it and 👍 the existing issue instead.

🤖 Generated with Claude Code

[arrrggghhh]

put "use japanese when respond" in your memory file.

[kaminuma]

thanks comment！

Sorry if this is a misunderstanding,
But when I mentioned localization, I was referring to things like the options Claude shows, such as:

Yes
Yes......
No...

as well as the language used when setting up sub-agents.
Does the language setting in Memory also affect those parts?

for example

[catherinewu]

duplicate with 2415, closing

[github-actions]

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.