[BUG] Lock keys (Caps Lock, Num Lock) output raw escape sequences in input

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?

Pressing Caps Lock inserts [57358u and Num Lock inserts a similar escape sequence as raw text. Happens in both VS Code panel and terminal. terminal.integrated.keyboard.enableKeyboardProtocol: false did not help. Windows 11, VS Code.

What Should Happen?

Lock/modifier keys (Caps Lock, Num Lock, Scroll Lock) should be silently ignored and not insert any text.

Error Messages/Logs

N/A

Steps to Reproduce

Steps to reproduce:

1. Open VS Code on Windows 11
2. Open Claude Code (either via the panel icon or by running claude in the terminal)
3. Click into the input field
4. Press Caps Lock or Num Lock
5. Raw escape sequence like [57358u appears in the input

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude Code v2.1.84

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_