flake/nixos/profiles/common/core/nix/gc.nix

{
  nix = {
    ### Auto hard linking
    settings.auto-optimise-store = true;

    ### Automatically delete older NixOS builds
    gc = {
      automatic = true;
      dates = "weekly";
      options = "--delete-older-than 7d";
    };

    ### optimiser
    optimise = {
      automatic = true;
      dates = ["03:45"];
    };
  };
}