[BUG] Raw CSI u escape sequence [57358u] (Caps Lock) displayed in VSCode 1.112 terminal (v2.1.83 regression)

Bug Description

Pressing Caps Lock causes the raw CSI u escape sequence [57358u] to appear in the input area. 57358 is the Caps Lock keycode in the Kitty keyboard protocol (functional key base 57344 + 14).

The context progress bar in the status line also renders with garbled Unicode characters.

Regression

• v2.1.83: Bug present
• v2.1.81: Bug NOT present — downgrading via npm install -g @anthropic-ai/claude-code@2.1.81 resolves the issue

Likely related to the terminal color/rendering changes introduced in v2.1.83.

Environment

• Claude Code: v2.1.83
• Terminal: VSCode integrated terminal (1.112.0, arm64)
• OS: macOS (Apple Silicon, Darwin 25.2.0)
• Shell: zsh

Steps to Reproduce

1. Open Claude Code v2.1.83 in VSCode integrated terminal
2. Press Caps Lock
3. Observe [57358u] appearing as literal text in the input area

Expected Behavior

Caps Lock keypress should be silently ignored or handled internally, not displayed as a raw escape sequence.

Workaround

Downgrade to v2.1.81:

npm install -g @anthropic-ai/claude-code@2.1.81

Screenshot

https://github.com/anthropics/claude-code/issues/38650#issuecomment-4125034827