[BUG] VS Code plugin: scrolling up deletes the current message and replaces it with the previous one

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?

Inside VS Code, in the Claude Code chat, when writing a long prompt, the start of the prompt goes out of the view, which is normal. To preview the message or to edit it before sending it, a natural thing to do is to press the up arrow button to get to the beginning of the prompt. Instead of getting to the top and stopping, the long message we spent a lot of time writing gets deleted and replaced with the message we sent earlier. This is a serious issue.

What Should Happen?

When the up arrow is pressed, the prompt should scroll to the top of the message and stop. Not get deleted and replaced with the message that was previously sent.

Error Messages/Logs

Steps to Reproduce

1. Exchange a few messages with Claude.
2. Write a long prompt.
3. Press the up arrow to get to the beginning of the current message. Users would either keep it pressed until it stops, or press it many times. often more than it is enough.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.246 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_