[BUG] Last character of Korean input is sent as a separate message in VS Code native extension

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?

Bug Description

When using the Claude Code native VS Code extension in my first time, sending a message in Korean results in the last character being sent as a separate message.

For example, if the user types and sends 테스트, two chat messages appear:

1. 테스트
2. 트

This happens even though the user pressed send only once.

What Should Happen?

Expected Behavior

The message should be sent exactly as typed, as a single chat message.
(Example: typing and sending 테스트 → 테스트 in one chat)

Actual Behavior

The last character of the message is sent as a separate chat message.
(Example: typing and sending 테스트 → results in two messages: 테스트 and 트)

Error Messages/Logs

Steps to Reproduce

1. Open VS Code with the Claude Code native extension installed.
2. Type a sentence in Korean (e.g., 테스트) in the Claude chat input.
3. Press Enter (send).
4. Observe that two separate chat messages are sent:

• First message: 테스트
• Second message: 트

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.1 (Claude Code)

Platform

Other

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

<img width="1988" height="1117" alt="Image" src="https://github.com/user-attachments/assets/8d801a05-6c19-4532-b39d-0b92c66e28b6" />