{
  description = "NixOS System Configuration for duckland.org";

  # Binary cache configuration for faster builds
  nixConfig = {allowUnfree = true;};

  inputs = {
    # nixvim.url = "github:nix-community/nixvim";
    nixvim.url = "github:nix-community/nixvim/nixos-25.11";
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
    # nixpkgs.url = "github:nixos/nixpkgs/nixos-25.11";
    sops-nix.url = "github:Mic92/sops-nix";
    nixpkgs-stable.url = "github:nixos/nixpkgs/nixos-25.11";
    # disko.inputs.nixpkgs.follows = "nixpkgs";
    # disko.url = "github:nix-community/disko";
    bzmenu.url = "github:e-tho/bzmenu";
    catppuccin.url = "github:catppuccin/nix";
    colmena.url = "github:zhaofengli/colmena";
    colmena.inputs.nixpkgs.follows = "nixpkgs";
    home-manager.url = "github:nix-community/home-manager";
    # home-manager.url = "github:nix-community/home-manager/release-25.11";
    home-manager.inputs.nixpkgs.follows = "nixpkgs";
    naviterm.url = "gitlab:detoxify92/naviterm";
    nixos-hardware.url = "github:NixOS/nixos-hardware/master";
    nvf.url = "github:notashelf/nvf";
    nvf.inputs.nixpkgs.follows = "nixpkgs";
  };

  outputs = inputs @ {
    self,
    catppuccin,
    colmena,
    home-manager,
    nix,
    nixos-hardware,
    nixpkgs,
    nixpkgs-stable,
    sops-nix,
    ...
  }: let
    inherit (self) outputs;
    nixpkgsPkg = import inputs.nixpkgs {
      system = "x86_64-linux";
      config = {
        allowUnfree = true;
      };
    };
    lib = inputs.nixpkgs.lib // home-manager.lib;

    # Helper for consistent specialArgs across all configurations
    mkSpecialArgs = { }: {
      inherit inputs outputs;
    };

    # Helper for nixosSystem configuration
    mkNixosSystem = { modules, system ? "x86_64-linux" }: lib.nixosSystem {
      inherit system;
      specialArgs = mkSpecialArgs { };
      modules = [ { nixpkgs.config.allowUnfree = true; } ] ++ modules;
    };
  in {
    inherit lib;
    # Remove redundant allowUnfreePredicate - allowUnfree covers all unfree packages
    # nixpkgs.config.allowUnfreePredicate = pkg:
    #   builtins.elem (lib.getName pkg) ["widevine-cdm"];
    colmena = {
      meta = {
        nixpkgs = nixpkgsPkg;
        specialArgs = mkSpecialArgs { };
      };
      # ace = import ./hosts/ace/colmena.nix;          # Acer C720
      book = import ./hosts/book/colmena.nix; # Google Pixelbook 2017 w/ nvme.
      display = import ./hosts/display/colmena.nix; # Pi4
      # eve = import ./hosts/eve/colmena.nix; # Google Pixelbook 2017 w/ eMMC.
      fred = import ./hosts/fred/colmena.nix; # acer server
      loki = import ./hosts/loki/colmena.nix; # Dell XPS 13
      # pi1 = import ./hosts/pi1/colmena.nix;
      pocket2 = import ./hosts/pocket2/colmena.nix;
      smaug = import ./hosts/smaug/colmena.nix; # Thinkpad x260 # FIXME - broken ssd
      w1 = import ./hosts/w1/colmena.nix; # Hetzner VPS
      # w2 = import ./hosts/w2/colmena.nix;
    };

    nixosConfigurations = {
      # clients
      ace = mkNixosSystem { modules = [./hosts/ace]; };
      dragon = mkNixosSystem { modules = [./hosts/dragon]; };
      book = mkNixosSystem { modules = [./hosts/book]; };
      loki = mkNixosSystem { modules = [./hosts/loki]; };
      pocket2 = mkNixosSystem { modules = [./hosts/pocket2]; };
      smaug = mkNixosSystem { modules = [./hosts/smaug]; };
      t2 = mkNixosSystem { modules = [./hosts/t2]; };
      pi1 = mkNixosSystem { modules = [./hosts/pi1]; };

      # servers
      display = mkNixosSystem { modules = [./hosts/display]; };
      fred = mkNixosSystem { modules = [./hosts/fred]; };
      vm = mkNixosSystem {
        modules = [
          "${nixpkgs}/nixos/modules/installer/cd-dvd/installation-cd-graphical-gnome.nix"
          "${nixpkgs}/nixos/modules/installer/cd-dvd/channel.nix"
          ./hosts/vm
        ];
      };
      harper2 = mkNixosSystem { modules = [./hosts/harper2]; };
      harper = mkNixosSystem { modules = [./hosts/harper]; };
      nuwww = mkNixosSystem { modules = [./hosts/nuwww]; };
      pihole = mkNixosSystem { modules = [./hosts/pihole]; };
      www2 = mkNixosSystem { modules = [./hosts/www2]; };
      w1 = mkNixosSystem { modules = [./hosts/w1]; };
      # w2 = mkNixosSystem { modules = [./hosts/w2]; };
    };
  };
}