{ config, pkgs, lib, disko, sydnix-cli, ... }:
{
  imports = [
    ./hardware-configuration.nix
    ./disko-config.nix
  ];

  # TODO: Remove; this is temporary!
  networking.firewall.allowedTCPPorts = [ 8080 ];

  sydnix = {
    filesystemType = "btrfs";

    tailscale.enable = true;

    dropbox.enable = true;

    users.users = [
      "crumb"
    ];

    impermanence = {
      enable = true;
      directories = [
        # "Warning: Neither /var/lib/nixos nor any of its parents are persisted.
        # This means all users/groups without specified uids/gids will have them
        # reassigned on reboot."
        "/var/lib/nixos"
        # We don't want to have different ssh keys on reboot, because ssh keys
        # are expected to consistently identify machines... I think.  I mostly
        # just think it's annoying to edit ~/.ssh/known_hosts all the time.
        "/etc/ssh"
      ];
      rollback = {
        enable = true;
        device = "/dev/sda2";
        subvolume = "rootfs";
      };
    };
  };

  boot = {
    loader = {
      systemd-boot.enable = true;
      efi.canTouchEfiVariables = false;
    };
  };

  # VM-specific. }:3
  fileSystems."/persist/dots" = {
    device = "mount-dots";
    fsType = "virtiofs";
    mountPoint = "/persist/dots";
  };

  # networking.hostName = "nixos-testbed";
  networking.hostId = "238e9b1e"; # head -c 8 /etc/machine-id

  time.timeZone = "America/Denver";

  i18n.defaultLocale = "en_US.UTF-8";

  console = {
    font = "Lat2-Terminus16";
    # keyMap = "us";
    useXkbConfig = true; # use xkb.options in tty.
  };

  services.xserver.enable = true;
  services.displayManager.sddm.enable = true;
  services.desktopManager.plasma6.enable = true;

  services.xserver.xkb.layout = "us";
  services.xserver.xkb.options = "caps:escape";

  environment.systemPackages = [
    pkgs.neovim
    pkgs.git
    sydnix-cli.packages.x86_64-linux.default
    (import ../../scripts/port-tools { inherit pkgs; })

    # Waypipe provides the equivalent of X11 forwarding for Wayland.  This is a
    # VM, so it's very handy.
    pkgs.waypipe
    pkgs.cachix
  ];

  services.openssh = {
    enable = true;
    settings.PermitRootLogin = "yes";
    settings.X11Forwarding = true;
  };

  # TODO: Move to defaults.
  users.mutableUsers = false;

  # services.xserver.windowManager.qtile = {
  #   enable = true;
  #   extraPackages = python3Packages: with python3Packages; [
  #     qtile-extras
  #     hy
  #   ];
  # };

  nix = {
    settings = {
      trusted-users = [
        "@wheel"
      ];
      substituters = [
        "https://cache.deertopia.net"
        "https://nix-community.cachix.org"
        "https://cache.nixos.org"
      ];
      trusted-public-keys = [
        (builtins.readFile ../../public-keys/deertopia-cache.pub.pem)
        "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
      ];
    };
  };

  # This option defines the first version of NixOS you have installed on this
  # particular machine, and is used to maintain compatibility with application
  # data (e.g. databases) created on older NixOS versions.
  #
  # Most users should NEVER change this value after the initial install, for any
  # reason, even if you've upgraded your system to a new NixOS release.
  #
  # This value does NOT affect the Nixpkgs version your packages and OS are
  # pulled from, so changing it will NOT upgrade your system - see
  # https://nixos.org/manual/nixos/stable/#sec-upgrading for how to actually do
  # that.
  #
  # This value being lower than the current NixOS release does NOT mean your
  # system is out of date, out of support, or vulnerable.
  #
  # Do NOT change this value unless you have manually inspected all the changes
  # it would make to your configuration, and migrated your data accordingly.
  #
  # For more information, see `man configuration.nix` or
  # https://nixos.org/manual/nixos/stable/options#opt-system.stateVersion .
  system.stateVersion = "24.05"; # Did you read the comment?
}