NixOS CI and Code Cleanup

This skill provides context about the CI workflow and code cleanup tools used in this repository.

CI Workflow

The CI is defined in @.github/workflows/ci.yml and runs three main checks:

1. Flake Check (nix flake check --no-build)

   • Validates flake syntax and structure
   • Checks all NixOS configurations
   • Ensures all outputs are buildable
   • Does NOT build derivations (fast check)

2. Statix (nix run nixpkgs#statix -- check .)

   • Lints Nix code for common issues and anti-patterns
   • Suggests best practices and improvements
   • Can auto-fix issues with statix fix

3. Deadnix (nix run nixpkgs#deadnix -- .)

   • Detects unused code and bindings
   • Finds dead let bindings, function arguments, etc.
   • Can auto-fix with deadnix -e

Running Checks Locally

Always run these before committing:

# Quick check (no builds)
nix flake check --no-build

# Lint for anti-patterns
nix run nixpkgs#statix -- check .

# Find dead code
nix run nixpkgs#deadnix -- .

Auto-fixing Issues

# Fix statix issues
nix run nixpkgs#statix -- fix .

# Remove dead code
nix run nixpkgs#deadnix -- -e .

Common Issues

Unused Let Bindings

# Bad - 'foo' is never used
let
  foo = "unused";
  bar = "used";
in bar

# Good - removed unused binding
let
  bar = "used";
in bar

Unused Function Parameters

# Bad - 'pkgs' is never used
{ pkgs, lib, ... }: {
  imports = [ ];
}

# Good - removed from signature
{ lib, ... }: {
  imports = [ ];
}

Best Practices

1. Always run /nix-check slash command after making changes
2. Use statix and deadnix to keep code clean
3. CI runs on every push and PR
4. All checks must pass before merging