[BUG] Fullscreen mouse movement generates garbage characters in input command line

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?

I just installed Claude and this is my first time using it. I entered /TUI Fullscreen then I moved my mouse. I see garbage characters being generated on the input command line.

What Should Happen?

As I move my mouse around, I'm not expecting garbage characters to be generated.

Error Messages/Logs

Steps to Reproduce

1) Enter /TUI Fullscreen
2) Move the mouse

Claude Model

Sonnet (default)

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Claude Code version 2.1.118

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

When I restarted Claude and entered /tui fullscreen it said I was already in fullscreen and not getting garbage. I then entered /tui default and now I can't enter any command. Screen shot

<img width="1908" height="740" alt="Image" src="https://github.com/user-attachments/assets/b465afcd-5ba2-4be8-92fd-72ebd2e93c3a" />

Now I restart Claude and issue /tui fullscreen and now I get the garbage

<img width="1920" height="1128" alt="Image" src="https://github.com/user-attachments/assets/cf4d7c8d-9eaf-4f95-bf06-3bdcc8c105f7" />