base: put common GUI programs behind option

base/default.nix

@@ -1,6 +1,7 @@
 { ... }:
 {
   imports = [
+    ./gui-programs.nix
     ./networking.nix
     ./nix.nix
     ./programs.nix

base/gui-programs.nix

@@ -1,5 +1,8 @@
-{ pkgs, ... }:
+{ pkgs, lib, config, ... }:
 {
+  options.my.gui.enable = lib.mkEnableOption "System has some kind of screen attached";
+
+  config = lib.mkIf config.my.gui.enable {
     environment.systemPackages = with pkgs; [
       element-desktop
       feh
@@ -28,4 +31,5 @@
 
     # NOTE: needed for home emacs configuration
     nixpkgs.config.input-fonts.acceptLicense = true;
+  };
 }

boreal.nix

@@ -3,7 +3,6 @@
   imports = [
     # Default configuration
     ./base
-    ./base/gui-programs.nix
 
     # Module definitions
     ./modules

hosts/boreal/default.nix

@@ -102,6 +102,7 @@ in
     };
   };
   my.displayManager.sddm.enable = true;
+  my.gui.enable = true;
 
   my.wakeonwlan.interfaces.phy0.methods = [
     "magic-packet"

hosts/zephyrus/default.nix

@@ -62,6 +62,7 @@ in
     fwupd.enable = true;
   };
   my.displayManager.sddm.enable = true;
+  my.gui.enable = true;
 
   environment.systemPackages = with pkgs; [
     arandr

zephyrus.nix

@@ -3,7 +3,6 @@
   imports = [
     # Default configuration
     ./base
-    ./base/gui-programs.nix
 
     # Module definitions
     ./modules