{
  systemConfiguration = { config, ... }: {
    isNormalUser = true;
    # TODO: Don't hard-code `persist`.  Use
    # config.sydnix.impermanence.persistGroupName.
    extraGroups = [
      # Admin account.
      "wheel"
      # Default permissions to modify /persist.
      "persist"
      # Can modify the files served by Nginx.
      "nginx"
      # Can modify Deertopia's git-annex repos.
      "annex"
      # Can modify Deertopia's Jellyfin libraries.
      "jellyfin"
      # Can access slskd's downloads.
      "slskd"
      # Can access Nixarr's media.
      "media"
    ];
    initialHashedPassword =
      "$y$j9T$aEFDDwdTZbAc6VQRXrkBJ0$K8wxTGTWDihyX1wxJ.ZMH//wmQFfrGGUkLkxIU0Lyq8";

    openssh.authorizedKeys.keyFiles = [
      ../../public-keys/ssh/crumb-at-guix-rebound.pub
      ../../public-keys/ssh/crumble-at-fruitbook.pub
      ../../public-keys/ssh/crumb-at-nixos-testbed.pub
      ../../public-keys/ssh/termux.pub
      ../../public-keys/ssh/windows.pub
    ];
  };

  homeConfiguration = { config, lib, pkgs, ... }: {
    imports = [
      ./files.nix
    ];

    programs.bash.enable = true;

    home.sessionVariables = {
      "EDITOR" = "nvim";
      "VISUAL" = "nvim";
    };

    home.packages = [
      pkgs.btop
    ];

    sydnix = {
      impermanence = {
        enable = true;
        directories = [
          ".ssh"
        ];
      };
      users.crumb.git.enable = true;
      users.crumb.nvim.enable = true;
    };

    # Don't touch!
    home.stateVersion = "18.09";
  };
}