feat(plugins): add windows-nul-fix plugin to auto-remove problematic nul files

[kp222x]

Summary

Adds a new plugin that automatically removes the problematic nul files created by Claude Code on Windows.

This is a workaround for the long-standing issue where Claude Code uses 2>nul (Windows CMD syntax) when running in Git Bash or other Unix-like shells on Windows, creating a literal file named nul instead of redirecting to the null device.

The Problem

Impact: 60+ users affected over 4+ months (see issue comments)

When Claude runs bash commands on Windows:

• Uses 2>nul for stderr redirection (CMD syntax)
• Git Bash treats nul as a regular filename
• Creates a literal file that:
  • Cannot be deleted via Windows Explorer or PowerShell
  • Breaks git add and git commit operations
  • Can corrupt source control history
  • Reappears after each bash command

The Solution

This plugin adds a PostToolUse hook that:

1. Only activates on Windows (os.platform() === "win32")
2. Runs after every Bash tool execution
3. Silently removes any nul file in the current working directory
4. Does not interrupt workflow on errors

Plugin Structure

windows-nul-fix/
├── .claude-plugin/
│   └── plugin.json      # Plugin metadata (Windows-only)
├── hooks/
│   └── hooks.json       # PostToolUse hook configuration
├── scripts/
│   └── remove-nul.js    # NUL file removal script
└── README.md            # Documentation with manual workarounds

Test Plan

• JavaScript syntax validation passes
• plugin.json is valid JSON
• hooks.json follows plugin wrapper format
• Script only runs on Windows (platform check)
• Handles missing input gracefully
• Does not block workflow on errors

Test Evidence

### Test 2: Validate JavaScript Syntax
✅ JavaScript syntax valid

### Test 3: Validate plugin.json
{
  "name": "windows-nul-fix",
  "version": "1.0.0",
  "description": "Automatically removes 'nul' files created by Claude Code on Windows...",
  ...
}
✅ plugin.json is valid JSON

Installation (for users)

Once merged, users can install via:

claude /plugin install windows-nul-fix

Or manually copy to ~/.claude/plugins/

Related

• Fixes [BUG] file named nul created on windows #4928
• Depends on fix(plugin-dev): support plugin wrapper format in validate-hook-schema.sh #13948 for proper hooks.json validation (uses wrapper format)

🤖 Generated with Claude Code

[ThoughtPhotography]

I can confirm this is an annoying issue on Win, and it's not just Git that doesn't like these files

I've added this to my CLAUDE.md, but it's not 100% reliable

## Important Notes

### Windows-Specific: NUL File Handling
**CRITICAL:** On Windows, avoid creating files named "nul" as they are reserved device names and cause severe issues:
- Windows Explorer cannot delete them (requires admin + force delete)
- Git cannot track/ignore them properly
- File sync tools (FreeFileSync, robocopy) fail when encountering them
- They break file operations in the containing directory

**Prevention:**
- NEVER use `2>nul` in bash commands (creates a literal file named "nul")
- Use `2>/dev/null` on Unix/Mac, `2>$null` in PowerShell, or omit error redirection entirely
- Prefer PowerShell commands on Windows when shell redirection is needed

**If "nul" files exist:**
```powershell
# Remove with PowerShell (run as Administrator if needed)
Remove-Item -Path "path\to\nul" -Force

# Or use full UNC path syntax
del "\\?\C:\full\path\to\nul"