[BUG] Conversation titles always in English even when user messages are in Chinese

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Conversation titles in VSCode extension are always generated in English, even when the user's messages are entirely in Traditional Chinese. Previously, titles were auto-generated in the same language as the user's input. This changed recently without any settings update.

What Should Happen?

Conversation titles should be auto-generated in the same language as the user's input. If the user writes in Chinese, the title should be in Chinese.

Error Messages/Logs

Steps to Reproduce

1. Open Claude Code in VSCode extension
2. Start a new conversation in Traditional Chinese (e.g. "檢查類別設定中的交貨方式是否沒有使用")
3. The auto-generated conversation title is in English instead of Chinese

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

v2.1.83

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Windows Terminal

Additional Information

_No response_