# Git Hooks - Simple Declarative Setup

## Concept

Hooks are defined in Nix (`flake.nix`) and installed by running `nix flake check` once.

**No systemd services, no activation scripts, no complexity.**

## How It Works

### 1. Hooks Defined in Nix
`flake.nix`:
```nix
checks.${system}.pre-commit-check = git-hooks.lib.${system}.run {
  src = ./.;
  hooks = {
    nixfmt.enable = true;
    statix.enable = true;
    deadnix.enable = true;
  };
};
```

### 2. Installation
Run once on each host:
```bash
nix flake check
```

This installs the hooks and creates `.git/hooks/pre-commit`.

### 3. Automatic
- ✅ Hooks run on every `git commit`
- ✅ CI runs `nix flake check` automatically
- ✅ Hooks checked on every push/PR

## Usage

### Install Hooks (One-Time Per Host)

```bash
# From the flake directory
nix flake check

# You should see hooks installing
```

### Verify Installation

```bash
ls -la .git/hooks/
```

Should show `pre-commit` (and potentially other hooks).

### Test Hooks

```bash
# Create a file with bad formatting
echo "broken { }" > test.nix

# Try to commit (should fail)
git add test.nix
git commit -m "test"

# Clean up
rm test.nix
```

## What's Declarative

| Aspect | Status |
|---------|--------|
| Hook definitions | ✅ Yes - in `flake.nix` |
| Hook installation | ✅ Yes - via `nix flake check` |
| CI integration | ✅ Yes - via `nix flake check` in workflows |
| Local git hooks | ✅ Yes - run automatically on commit |
| No systemd services | ✅ Removed - too complex |
| No activation scripts | ✅ Removed - unnecessary |
| One-time setup | ✅ Yes - run `nix flake check` once per host |

## Files

| File | Status |
|------|--------|
| `flake.nix` | ✅ Hook definitions |
| `.github/workflows/flake-check.yaml` | ✅ CI uses `nix flake check` |
| `.editorconfig` | ✅ Code style |
| `modules/git-hooks/default.nix` | ❌ **DELETED** - Not needed |
| `hosts/*/default.nix` | ✅ **CLEANED** - Removed git-hooks |

## Next Steps

1. Test locally:
   ```bash
   nix flake check
   ls -la .git/hooks/
   echo "broken { }" > test.nix
   git add test.nix
   git commit -m "test"  # Should fail
   rm test.nix
   ```

2. Commit changes:
   ```bash
   git add .
   git commit -m "Simplify: Git hooks via nix flake check (no systemd, no activation)"
   git push
   ```

3. Run `nix flake check` on each host when you next rebuild

## This Is The Right Approach Because

| Issue | Overcomplicated Solution | Simple Solution |
|-------|----------------------|----------------|
| Declarative | ❌ Systemd service is separate from Nix | ✅ Hooks in `flake.nix`, install via `nix flake check` |
| Simple | ❌ Multiple layers (activation, systemd) | ✅ One command: `nix flake check` |
| Idempotent | ❌ Runs on every rebuild | ✅ Idempotent - run once per host |
| Reproducible | ❌ Depends on systemd state | ✅ Pure Nix |

## Summary

**The simplest declarative approach:**

1. Define hooks in `flake.nix` ✅ Already done
2. Run `nix flake check` once per host ✅ To do
3. That's it! Hooks work automatically ✅ Declarative

No systemd services. No activation scripts. No complexity.