{
  flake-file = { 
    nixConfig = {
      abort-on-warn = true;
      extra-experimental-features = [
        "flakes"
        "nix-command"
        "pipe-operators"
      ];
      extra-substituters = [
        "https://numtide.cachix.org"
        #"https://nix-gaming.cachix.org"
        #"https://nixpkgs-wayland.cachix.org"
      ];
      extra-trusted-public-keys = [
        "numtide.cachix.org-1:2ps1kLBUWjxIneOy1Ik6cQjb41X0iXVXeHigGmycPPE="
        #"nix-gaming.cachix.org-1:nbjlureqMbRAxR1gJ/f3hxemL9svXaZF/Ees8vCUUs4="
        #"nixpkgs-wayland.cachix.org-1:3lwxaILxMRkVhehr5StQprHdEo4IrE8sRho9R9HOLYA="
      ];
    };
  };

  den.aspects = {
    base = {
      nixos = 
        { pkgs, config, ... }:
        {
          nix = {
            # See https://hachyderm.io/@leftpaddotpy/112539055867932912
            channel.enable = false;
            # From https://jackson.dev/post/nix-reasonable-defaults/
            extraOptions = ''
              connect-timeout = 5
              log-lines = 50
              min-free = 128000000
              max-free = 1000000000
              fallback = true
            '';
            optimise.automatic = true;

            settings = {
              auto-optimise-store = true;
              # See https://discourse.nixos.org/t/24-05-add-flake-to-nix-path/46310/9
              nix-path = [ "nixpkgs=${pkgs.path}" ];
              trusted-users = [
                "root"
                "kirbara"
              ];
              experimental-features = [
                "flakes"
                "nix-command"
                "pipe-operators"
              ];
              # ----
              substituters = [
                "https://nix-community.cachix.org"
                #"https://cache.garnix.io"
              ];
              trusted-public-keys = [
                "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
                #"cache.garnix.io:CTFPyKSLcx5RMJKfLo5EEPUObbA78b0YQ2DTCJXqr9g="
              ];
              builders-use-substitutes = true;
              # ----
              warn-dirty = false;
              tarball-ttl = 60 * 60 * 24; # 1 day tarball cache
            };
          };
        };
      };
    };
}