Escape sequence fragment [28~ leaks into terminal input on cmd.exe (Windows 11)

Description

When running Claude Code CLI on Windows 11, the escape sequence fragment [28~ repeatedly appears at the terminal input without any key being pressed. This does not happen in the terminal itself outside of Claude Code.

[28~ appears to be a fragment of the ANSI escape sequence for F15 (\e[28~), suggesting that Claude Code's UI is emitting escape sequences that the terminal cannot properly consume/suppress.

Steps to Reproduce

1. Open any terminal on Windows 11
2. Launch Claude Code CLI
3. Observe [28~ appearing in the input area without pressing any key

Expected Behavior

No escape sequence fragments should appear in the terminal input.

Actual Behavior

[28~ appears at the input unprompted.

Environment

• OS: Windows 11
• Claude Code CLI (latest)

Affected Terminals

This happens across all tested terminals:

• cmd.exe
• Windows PowerShell
• Rio
• Warp

Since it reproduces on every terminal, this is likely a Claude Code issue rather than a terminal-specific one.