If you're using NixOS with flakes and home-manager, this addresses the specific headache of overlays not applying when useGlobalPkgs is true. The core insight is simple but easy to miss: overlays defined in home.nix get ignored in that setup, they need to go in your system configuration instead. It includes decision matrices for where to put overlays based on your useGlobalPkgs setting, plus rule files covering flakes structure, host organization, and common mistakes. The documentation-first approach is a bit heavy-handed with the warnings, but honestly justified since most NixOS configuration issues come from not understanding the interaction between system and home-manager package scopes.
npx skills add https://github.com/lihaoze123/my-skills --skill nixos-best-practices