[BUG] Permission pattern matching fails when command contains # character

Description

Permission patterns with the :* wildcard do not match commands that contain the # character. This affects Nix flake commands specifically.

Steps to Reproduce

1. Add permission pattern to settings.json:

``json
"permissions": {
"allow": ["Bash(nix build:*)"]
}
``

1. Run command containing #:

``bash
nix build .#darwinConfigurations.default.system
``

1. Expected: Command auto-approves (matches Bash(nix build:*))
2. Actual: Claude prompts for permission

Working vs Non-Working

| Command | Pattern | Works? |
|---------|---------|--------|
| nix build /path/to/flake | Bash(nix build:*) | ✅ Yes |
| nix build .#target | Bash(nix build:*) | ❌ No |
| nix flake check /path | Bash(nix flake check:*) | ✅ Yes |
| nix flake show .#foo | Bash(nix flake show:*) | ❌ No |

Workaround

Use command variants that don't require #:

• nix flake check /absolute/path instead of nix build .#target
• Specify full path without # fragment

Environment

• Claude Code version: 2.0.56
• OS: macOS (Darwin 25.1.0)
• Shell: zsh

Impact

This affects all Nix/flake users who want to auto-approve common build commands. The # character is fundamental to Nix flake syntax for specifying outputs.