Ctrl-G external editor spawn regression introduced between 2.1.132 and 2.1.138 (Windows + Cygwin/MSYS2)

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?

Ctrl-G external editor spawn regression introduced between 2.1.132 and 2.1.138

Summary

Pressing Ctrl-G to open the external $EDITOR causes the Claude Code TUI
to hang ("spinner of death") in Claude Code 2.1.138 and 2.1.140.
The same workflow worked correctly in 2.1.132.

This is a regression confirmed by version bisection on a single machine
with no other environment changes.

Reproduction

1. Set EDITOR=vim (or $VISUAL=vim).
2. Start claude in a terminal.
3. Press Ctrl-G to open the external editor.

Expected: vim opens in the current terminal, accepts input, exits cleanly,
control returns to Claude Code with the edited prompt.

Actual (2.1.138 / 2.1.140): TUI freezes with the spinner; vim never
becomes interactive. Killing the editor process is required to recover.

Environment

• OS: Windows 11 Enterprise 22H2 (Build 22631)
• Shell / Terminal: Reproduced in two independent setups:
• Cygwin 3.6.x + tmux + mintty (primary working environment)
• Git for Windows 2.54.0 (MSYS2) + mintty (secondary, used for cross-check)
• Editor: vim 9.1 (Git for Windows MSYS2 build); also reproduced with

Cygwin's vim. Editor binary itself works correctly when invoked directly
in the shell — the issue is the spawn from Claude Code.

• Claude Code versions on the same machine (binaries in

~/.local/share/claude/versions/):

• 2.1.132 (2026-05-07) → works
• 2.1.138 (2026-05-11) → broken
• 2.1.140 (2026-05-13) → broken

What I ruled out

• Cygwin runtime as cause: repro also occurs under Git for Windows

MSYS2 (different POSIX emulation, no cygwin1.dll); confirmed via
uname -a and ldd of the editor binary.

• vim configuration: repro persists with vim -u NONE -N.
• Outdated Git for Windows: repro persists after updating from

2.53.0.windows.1 to 2.54.0.windows.1.

• mintty pty issues alone: Claude Code 2.1.132 spawns vim cleanly in

the exact same mintty session, so the host terminal is not the cause.

Workaround

A winpty-based wrapper script (winpty vim "$@") makes vim spawn at all
under 2.1.138/2.1.140, but causes input-handling issues in insert mode
(ESC inserts garbage instead of leaving insert mode). The only clean
workaround currently is to stay on 2.1.132.

Likely related issues

• #9218 (Fedora 42 + vim/nano — similar Ctrl-G symptom, no version bisection)
• #36516 (Ctrl-G suspends TUI)
• #27001 (Ctrl-G with kitty keyboard protocol)

Useful next step for triage

Diffing the editor-spawn / pty-handover logic between 2.1.132 and 2.1.138
should isolate the offending change.

What Should Happen?

Behaviour of editor spawn should behave exactly as in Version 2.1.132

Error Messages/Logs

Steps to Reproduce

1. Set EDITOR=vim (or $VISUAL=vim).
2. Start claude in a mintty terminal.
3. Press Ctrl-G to open the external editor.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.132

Claude Code Version

2.1.140

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_