{
  description = "NixOS configuration of Ryan Yin";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-23.11";
    impermanence.url = "github:nix-community/impermanence";
    nixos-hardware.url = "github:NixOS/nixos-hardware/master";
  };

  outputs = inputs @ {
    nixpkgs,
    nixos-hardware,
    ...
  }: {
    nixosConfigurations = {
      ai = nixpkgs.lib.nixosSystem {
        system = "x86_64-linux";
        specialArgs = inputs // {username = "ryan";};
        modules = [
          {networking.hostName = "ai";}

          ./configuration.nix

          ../modules/base.nix
          ../modules/nixos/base/i18n.nix
          ../modules/nixos/base/user-group.nix
          ../modules/nixos/base/networking.nix

          ../hosts/idols/ai/hardware-configuration.nix
          ../hosts/idols/ai/impermanence.nix
        ];
      };

      shoukei = nixpkgs.lib.nixosSystem {
        system = "x86_64-linux";
        specialArgs = inputs // {username = "ryan";};
        modules = [
          # Building on a USB installer is buggy, lack of disk space, memory, trublesome to setup substituteers, etc.
          # so we disable apple-t2 module here to avoid build kernel during the initial installation, and enable it after the first boot.
          # nixos-hardware.nixosModules.apple-t2
          ({pkgs, ...}: {
            networking.hostName = "shoukei";
            boot.kernelPackages = pkgs.linuxPackages_latest;  # Use latest kernel for the initial installation.
            # hardware.apple-t2.enableAppleSetOsLoader = true;
          })

          ./configuration.nix

          ../modules/base.nix
          ../modules/nixos/base/i18n.nix
          ../modules/nixos/base/user-group.nix
          ../modules/nixos/base/networking.nix

          ../hosts/12kingdoms/shoukei/hardware-configuration.nix
          ../hosts/12kingdoms/shoukei/impermanence.nix
        ];
      };
    };
  };
}