[BUG] Backslashes stripped from ${CLAUDE_PLUGIN_ROOT} in hook commands #23204

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, plugin hooks using ${CLAUDE_PLUGIN_ROOT} fail because backslashes are stripped from the path during variable substitution.

What Should Happen?

The ${CLAUDE_PLUGIN_ROOT} variable should be properly escaped or converted to Unix-style paths (/c/Users/...) before being passed to bash on Windows.

Error Messages/Logs

Hook SessionStart:startup (SessionStart) error: /bin/bash: C:UsersCyril.claudepluginscacheclaude-plugins-officialsuperpowers4.1.1/hooks/session-start.sh: No    
  such file or directory

Steps to Reproduce

1. Windows 11, Claude Code 2.1.31
2. Install superpowers plugin: /plugin install superpowers@claude-plugins-official
3. Start a new Claude Code session
4. Observe "SessionStart:startup hook error" message
5. Check debug log in ~/.claude/debug/.txt
   for the mangled path

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

No response

Claude Code Version

2.1.31

Platform

Other

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Workaround: Using a hardcoded Unix-style path
(/c/Users/Cyril/...) instead of
${CLAUDE_PLUGIN_ROOT} works correctly.

The issue appears to be in how Claude Code substitutes
the variable before passing to bash - Windows
backslashes aren't escaped or converted.

Plugin affected: superpowers
(https://github.com/obra/superpowers)