[Bug] Raw Kitty keyboard protocol sequences leak on modifier-only keypresses (WSL2)

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?

On WSL2, pressing Shift (and other modifier keys alone) causes the raw Kitty keyboard protocol sequence [57358u to appear inline in the terminal output. This corrupts
both the prompt input and any displayed text.

What Should Happen?

Modifier-only keypresses should be silently consumed and not produce visible output.

Error Messages/Logs

[57358uI[57358u

Steps to Reproduce

1. Launch claude in WSL2
2. Press and release the Shift key (without any other key)
3. Observe [57358u appearing in the terminal

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

4.6

Claude Code Version

2.1.84 (Claude Code)

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

WSL (Windows Subsystem for Linux)

Additional Information

_No response_