Plugin hooks fail on Windows: CLAUDE_PLUGIN_ROOT uses backslash paths incompatible with bash

Bug: Plugin hook CLAUDE_PLUGIN_ROOT uses Windows backslash paths, breaks /bin/bash execution

Description

On Windows, the ${CLAUDE_PLUGIN_ROOT} environment variable in plugin hook commands expands to a Windows-style path with backslashes (e.g., C:\Users\username\.claude\plugins\cache\...). When the hook is executed via /bin/bash (Git Bash), the backslashes are stripped, producing an invalid path like C:Userssapta.claudepluginscache....

This causes every plugin with a Stop hook to fail on every response, producing a visible error after each assistant message:

â—^O Ran 1 stop hook
  ⎿  Stop hook error: Failed with non-blocking status code: /bin/bash:
     C:Userssapta.claudepluginscacheclaude-code-pluginsralph-wiggum1.0.0/hooks/stop-hook.sh:
     No such file or directory

The hook file exists at the correct location and has proper execute permissions. The issue is purely the path separator handling.

Steps to Reproduce

1. Install any plugin with a Stop hook on Windows (e.g., ralph-wiggum)
2. Run any Claude Code session
3. Observe the stop hook error after each response

Expected Behavior

${CLAUDE_PLUGIN_ROOT} should be expanded with forward slashes (/) or the appropriate path format for the shell executing the hook. Since hooks are executed via /bin/bash on Windows (Git Bash), the path should use forward slashes.

Actual Behavior

${CLAUDE_PLUGIN_ROOT} expands with Windows backslashes (\), which bash interprets as escape characters, producing an invalid path.

Hook configuration (hooks.json)

{
  hooks: {
    Stop: [
      {
        hooks: [
          {
            type: command,
            command: ${CLAUDE_PLUGIN_ROOT}/hooks/stop-hook.sh
          }
        ]
      }
    ]
  }
}

Environment

• Claude Code: 2.1.42
• OS: Windows 11 Pro for Workstations (10.0.26220)
• Shell: bash (Git Bash via MSYS2)
• Plugin: ralph-wiggum 1.0.0 (affects any plugin with hooks)
• Plugin path: ~\.claude\plugins\cache\claude-code-plugins\ralph-wiggum\1.0.0\hooks\stop-hook.sh` (file exists, chmod +x)

Impact

• Non-blocking (doesn't break sessions), but produces a confusing error on every single response
• Affects all plugins with hooks on Windows, not just ralph-wiggum
• No user-side workaround since CLAUDE_PLUGIN_ROOT is set by Claude Code internally

Suggested Fix

Normalize CLAUDE_PLUGIN_ROOT (and any other path variables passed to hooks) to use forward slashes on Windows before passing to the shell, e.g.:

pluginRoot = pluginRoot.replace(/\\/g, '/');

Or use the MSYS2/Git Bash compatible path format (/c/Users/... instead of C:\Users\...).