{
  description = "Evie's machine configurations";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    home-manager = {
      url = "github:nix-community/home-manager";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs = {
    self,
    nixpkgs,
    home-manager,
  }: let
    common = {lib, ...}: {
      nix = {
        settings.experimental-features = ["nix-command" "flakes"];
        gc = {
          automatic = true;
          dates = "daily";
          options = "--delete-older-than 7d";
        };
        extraOptions = ''
          keep-outputs = true
          keep-derivations = true
        '';
      };
      nixpkgs.config.allowUnfree = true;
      home-manager = {
        useGlobalPkgs = true;
        useUserPackages = false;
      };
      networking.networkmanager.enable = true;
      services.power-profiles-daemon.enable = true;
      virtualisation.podman.enable = true;
      programs = {
        ssh.startAgent = true;
        dconf.enable = true;
        fish.enable = true;
        zsh.enable = true;
      };
      fonts.fontconfig.enable = true;
      environment.localBinInPath = true;
    };
    hardware-audio = {pkgs, ...}: {
      # Enable sound with pipewire.
      sound.enable = true;
      hardware.pulseaudio.enable = false;
      security.rtkit.enable = true;
      services.pipewire = {
        enable = true;
        alsa.enable = true;
        alsa.support32Bit = true;
        pulse.enable = true;
      };
      programs.noisetorch.enable = true;
    };
    hardware-bluetooth = {
      hardware.bluetooth = {
        enable = true;
        powerOnBoot = true;
      };
    };
  in {
    nixosConfigurations = {
      Legion = nixpkgs.lib.nixosSystem {
        system = "x86_64-linux";
        modules = [
          home-manager.nixosModules.home-manager
          common
          ./hosts/Legion/configuration.nix
          ./services/Legion.nix
        ];
      };
      Vanguard = nixpkgs.lib.nixosSystem {
        system = "x86_64-linux";
        modules = [
          home-manager.nixosModules.home-manager
          common
          hardware-audio
          hardware-bluetooth
          ./hosts/Vanguard/configuration.nix
          ./wm/sway.nix
          ./services/sshd
        ];
      };
      N0245 = nixpkgs.lib.nixosSystem {
        system = "x86_64-linux";
        modules = [
          home-manager.nixosModules.home-manager
          common
          hardware-audio
          hardware-bluetooth
          ./hosts/N0245/configuration.nix
          ./wm/sway.nix
          ./services/syncthing/N0245.nix
        ];
      };
    };
    homeConfigurations = {
      "tux" = home-manager.lib.homeManagerConfiguration {
        pkgs = nixpkgs.legacyPackages."aarch64-darwin";
        modules = [./hosts/Monarch/home.nix];
      };
      "xenia" = home-manager.lib.homeManagerConfiguration {
        pkgs = nixpkgs.legacyPackages."aarch64-linux";
        modules = [./hosts/Northstar/home.nix];
      };
    };
  };
}