Kitty keyboard protocol escape sequences leak into input (e.g. Caps Lock → [57358u)

Description

When using Claude Code in VS Code's integrated terminal with the Kitty keyboard protocol enabled (default in recent VS Code versions), pressing non-functional keys like Caps Lock produces raw escape sequences (e.g. [57358u) that leak into the input field.

Steps to Reproduce

1. Open Claude Code in VS Code integrated terminal (v1.113.0+)
2. Ensure terminal.integrated.keyboard.protocol is set to auto (default)
3. Press Caps Lock

Expected Behavior

Caps Lock (and other non-bound modifier keys) should be silently ignored.

Actual Behavior

The raw Kitty protocol escape sequence [57358u appears in the input field each time Caps Lock is pressed.

Environment

• Terminal: VS Code integrated terminal 1.113.0
• TERM: xterm-256color
• Shell: zsh 5.9
• OS: Linux (Ubuntu)

Workaround

Set terminal.integrated.keyboard.protocol to none in VS Code settings.