Feature Request: Session title language should respect `language` setting in settings.json

Problem

Currently, session titles are always auto-generated in English, even when:

• settings.json has "language": "ja"
• CLAUDE.md explicitly instructs to use Japanese titles (marked as highest priority)
• The entire conversation is conducted in Japanese
• Memory files reinforce the instruction

No matter what configuration is set, the auto-generated session title always defaults to English.

Expected Behavior

Session titles should be generated in the language specified by the language setting in settings.json. For example, if "language": "ja" is set, titles should be auto-generated in Japanese.

Additional Request

A /rename slash command to manually rename sessions from within a session would also be very helpful as a workaround. Currently there is no way to rename a session title from inside a running session.

Environment

• Claude Code (latest version as of March 2026)
• Windows 11
• settings.json with "language": "ja" configured