[BUG]: /mcp modal becomes unresponsive to all keys (arrows, Enter, Esc, Ctrl-C) — regression in 2.1.118/2.1.119

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?

After upgrading to Claude Code 2.1.119 (also reproduces on 2.1.118), opening the /mcp slash command
panel results in a fully frozen modal: arrow keys, Enter, and Esc are dropped, and the modal cannot
even be killed with Ctrl-C or Ctrl-\. The keys are reaching the process correctly (verified — see
below), so this appears to be a UI input-handling regression rather than a terminal issue.

Downgrading to 2.1.117 fully fixes it.

Possibly related to #42707 (Ink input hook race in MCP OAuth flow), but more severe — in #42707 keys
are still partially responsive and Ctrl-C still kills the modal. Here, signal handling itself is broken
from inside the modal.

What Should Happen?

/mcp modal should respond to navigation keys and Esc/Ctrl-C should dismiss it, as it does in 2.1.117
and earlier.

Error Messages/Logs

Steps to Reproduce

1. Run claude (v2.1.118 or v2.1.119, native installer on macOS)
2. Type /mcp → modal opens
3. Press any of: ↑ ↓ ← → Enter Esc — nothing happens
4. Press Ctrl-C — also nothing; modal cannot be dismissed
5. Only way out: kill the terminal session / SIGKILL from another shell

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.117

Claude Code Version

2.1.119 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

## Environment

• Claude Code versions tested:
• 2.1.117 — works correctly
• 2.1.118 — broken
• 2.1.119 — broken
• OS: macOS Darwin 25.3.0
• Shell: zsh
• Terminal: iTerm2 (also reproduces in tmux and outside tmux)
• Install method: native installer (~/.local/share/claude/versions/)
• TERM: xterm-256color

## Terminal verified healthy

Ran cat -v and confirmed all relevant keys produce correct escape codes:

• ↑ → ^[[A
• ↓ → ^[[B
• Esc → ^[

So keys are reaching the process — this is not a terminfo / Option-as-Esc issue.