[BUG] Windows: Hook .sh auto-detection resolves to WSL bash.exe instead of Git Bash when WSL is installed

Bug Description

On Windows systems with WSL installed, Claude Code's hook execution resolves bash to WSL's C:\Windows\System32\bash.exe instead of Git Bash's bash.exe, causing all plugin hooks using .sh scripts to fail.

Claude Code correctly detects the right bash path at startup:

Using bash path: "C:\Program Files\Git\bin\bash.exe"

But when executing hook commands, it uses generic bash which the Windows PATH resolves to WSL's bash.exe:

C:\Windows\System32\bash.exe → WSL bash → fails

Reproduction Steps

1. Install Git for Windows (provides Git Bash)
2. Install Docker Desktop (installs WSL automatically) or have WSL installed without a configured distro
3. Install any Claude Code plugin that uses .sh hooks (e.g., explanatory-output-style, learning-output-style, ralph-wiggum)
4. Start a Claude Code session

Expected Behavior

Hooks execute successfully using Git Bash.

Actual Behavior

Hook execution fails with:

<3>WSL (2) ERROR: CreateProcessCommon:559: execvpe /bin/bash failed : No such file or directory
<3>WSL (2) ERROR: CreateProcessCommon:562: Create process not expected to return

Or silently fails/produces no output.

Root Cause

The Windows PATH typically resolves bash in this order:

1. C:\Windows\System32\bash.exe (WSL - takes precedence)
2. C:\Program Files\Git\bin\bash.exe (Git Bash)

When a hook command is ${CLAUDE_PLUGIN_ROOT}/hooks-handlers/session-start.sh, Claude Code detects the .sh extension and auto-prepends bash, which resolves to WSL bash instead of Git Bash.

Affected Plugins

All 3 official plugins with .sh hooks:

• explanatory-output-style — hooks-handlers/session-start.sh
• learning-output-style — hooks-handlers/session-start.sh
• ralph-wiggum — hooks/stop-hook.sh

Environment

• OS: Windows 10/11 with WSL installed
• Claude Code: 2.x (tested on 2.1.x)
• Shell: Git Bash
• Extremely common scenario: Docker Desktop automatically installs WSL

Proposed Fix

Add cross-platform .cmd polyglot wrappers that:

• On Windows (cmd.exe): explicitly invoke Git Bash at its standard path
• On Unix/macOS: pass through to the .sh script natively

This approach requires no changes to the core binary and fixes all affected plugins.

Workaround

Manually edit each plugin's hooks.json to use the explicit Git Bash path:

{
  "command": "\"C:/Program Files/Git/usr/bin/bash.exe\" ${CLAUDE_PLUGIN_ROOT}/hooks-handlers/session-start.sh"
}

Note: Plugin updates overwrite this fix.

Related Issues

• #22700 — bash not in PATH (different root cause but same symptom area)
• #21468 — superpowers plugin fails on Windows
• #21878 — Windows hook execution issues
• PR #19084 — ralph-wiggum .cmd wrapper (narrow scope, same approach)