{ inputs, self, ... }: {
  flake.nixosModules.global = { config, pkgs, lib, ... }: {
    options.features.shells.defaultShell = lib.mkOption {
      type = inputs.helpers.mkEnumFromDirContents "${self}/modules/features/shells";
      default = "zsh";
    };

    config = {
      programs.${config.features.shells.defaultShell}.enable = true;

      users.defaultUserShell = pkgs.${config.features.shells.defaultShell};
      users.users."grey".shell = pkgs.${config.features.shells.defaultShell};
    };
  };
}