you know the drill at this point

modules/nixos/default.nix

@@ -1,43 +0,0 @@
-{ config, lib, namespace, ... }:
-let
-  inherit (lib) mkIf mkDefault mkOption mkMerge;
-  inherit (lib.types) nullOr enum;
-
-  cfg = config.${namespace};
-in
-{
-  options.${namespace} = {
-    preset = mkOption {
-      type = nullOr (enum [ "server" "desktop" ]);
-      default = null;
-      example = "desktop";
-      description = "Which defaults profile to start with";
-    };
-  };
-
-  config = mkMerge [
-    (mkIf (cfg.preset == "desktop") {
-      ${namespace} = mkDefault {
-        hardware.has = {
-          audio = true;
-        };
-
-        boot = {
-          quiet = true;
-          animated = true;
-        };
-
-        desktop.use = "plasma";
-        theming.enable = true;
-      };
-    })
-
-    (mkIf (cfg.preset == "server") {
-      ${namespace} = mkDefault {
-        services = {
-          networking.ssh.enable = true;
-        };
-      };
-    })
-  ];
-}

modules/nixos/shells/default.nix

@@ -0,0 +1,2 @@
+{ ... }:
+{}

modules/nixos/shells/zsh/default.nix

@@ -10,5 +10,7 @@ in
   };
 
   config = mkIf cfg.enable {
+    # Enable completion for sys-packages:
+    environment.pathsToLink = ["/share/zsh"];
   };
 }

modules/nixos/theming/default.nix

@@ -10,7 +10,9 @@ in
   ];
 
   options.${namespace}.theming = {
-    enable = mkEnableOption "enable theming";
+    enable = mkEnableOption "enable theming" // {
+      default = true;
+    };
   };
 
   config = mkIf cfg.enable {