Windows: bash popup window appears at startup due to -i flag in cygpath call #26440

Preflight Checklist

• I have searched existing issues and this hasn't been reported yet
• This is a single bug report (please file separate reports for different bugs)
• I am using the latest version of Claude Code

What's Wrong?

On Windows with Git Bash/MSYS2, Claude Code spawns a visible
bash popup window at startup with this command:

/usr/bin/bash --login -i -c cygpath -u 'c:\repos\os'

The -i (interactive) flag causes Windows to open a console window.
Since cygpath doesn't need an interactive shell, removing -i would
fix the popup.

Environment:

• OS: Windows
• Shell: MSYS2/Git Bash
• Claude Code running as VS Code extension

What Should Happen?

On Windows with Git Bash/MSYS2, Claude Code spawns a visible
bash popup window at startup with this command:

/usr/bin/bash --login -i -c cygpath -u 'c:\repos\os'

The -i (interactive) flag causes Windows to open a console window.
Since cygpath doesn't need an interactive shell, removing -i would
fix the popup.

Environment:

• OS: Windows
• Shell: MSYS2/Git Bash
• Claude Code running as VS Code extension

Error Messages/Logs

Steps to Reproduce

Steps to Reproduce
Environment:

OS: Windows 10/11
Claude Code running as VS Code extension
Git Bash / MSYS2 installed (required by Claude Code on Windows)
Working directory: any Windows path (e.g. c:\repos\os)
Steps:

Open VS Code on Windows with Git Bash/MSYS2 installed
Open a project folder with a Windows-style path (e.g. c:\repos\os)
Open Claude Code (via VS Code extension)
Observe a bash terminal popup window appears with title:

/usr/bin/bash --login -i -c cygpath -u 'c:\repos\os'
Window appears briefly then closes (flashes on screen)
Expected behavior:
No visible popup window. Path conversion should run headlessly.

Actual behavior:
A black bash console window flashes on screen every time Claude Code runs a command.

Root cause (suspected):
The -i (interactive) flag in the bash invocation forces Windows to open a console window. Since cygpath only does path conversion and does not require an interactive shell, removing -i should fix the issue.

Workarounds attempted (none effective):

Setting SHELL=pwsh in ~/.claude/settings.json
Setting CLAUDE_CODE_SHELL=pwsh
Setting CLAUDE_BASH_MAINTAIN_PROJECT_WORKING_DIR=1

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

No response

Claude Code Version

2.1.42

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

No response