CLAUDE_CODE_SHELL environment variable ignored on Windows

Description

The CLAUDE_CODE_SHELL environment variable is ignored on Windows. Claude Code always uses Git Bash (/usr/bin/bash) regardless of the setting.

Steps to reproduce

1. Set CLAUDE_CODE_SHELL in ~/.claude/settings.json:

``json
{
"env": {
"CLAUDE_CODE_SHELL": "C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe"
}
}
``

1. Also tried setx CLAUDE_CODE_SHELL powershell.exe (system environment variable)
2. Also tried short name powershell.exe instead of full path
3. Restart Claude Code in a new terminal window each time

Expected behavior

PowerShell is used as the shell for Bash tool calls.

Actual behavior

Git Bash (/usr/bin/bash) is always used regardless of the setting.

Environment

• OS: Windows 11 Pro for Workstations 10.0.26200
• Python: 3.13.12
• Claude Code: latest channel