nixfiles/nixos/environments/i3/xserver.nix

{pkgs, ...}: {
  services.xserver = {
    enable = true;
    displayManager = {
      defaultSession = "none+i3";
    };
    windowManager.i3 = {
      enable = true;
      extraPackages = with pkgs; [
        dmenu
        i3lock
      ];
    };
  };
}