Feature Request: Allow configuring language for auto-generated session names

Summary

Currently, Claude Code auto-generates session names in English regardless of the user's language or locale. There is no way to configure the language used for session name generation.

Proposal

Add a setting (e.g., in settings.json or CLAUDE.md) to control the language of auto-generated session names.

Example configuration:

{
  "sessionNameLanguage": "ja"
}

Or alternatively, detect the language from:

• The system locale
• The primary language used in CLAUDE.md
• The language of the user's first message in the session

Use Case

Non-English speaking users (Japanese, Korean, Chinese, Spanish, etc.) would benefit from session names generated in their native language for easier identification and management of sessions.

This is distinct from general CLI i18n (#4866), as it specifically concerns the AI-generated session name output rather than static UI text translation.

Environment

• OS: Windows 11
• Claude Code: Desktop app