nixos: show diff to current system at activation time

still requires further config to fully use fc-nixos specifics

common/default.nix

@@ -14,6 +14,7 @@ in
     ./packages.nix
     ./nitrokey.nix
     ./nix-settings.nix
+    ./upgrade-diff.nix
   ];
 
   services.davfs2.enable = true;

common/upgrade-diff.nix

@@ -0,0 +1,9 @@
+# MIT Jörg Thalheim - https://github.com/Mic92/dotfiles/blob/c6cad4e57016945c4816c8ec6f0a94daaa0c3203/nixos/modules/upgrade-diff.nix
+{ pkgs, ... }:
+{
+  system.activationScripts.diff = ''
+    if [[ -e /run/current-system ]]; then
+      ${pkgs.nix}/bin/nix store diff-closures /run/current-system "$systemConfig"
+    fi
+  '';
+}

home/modules/vscodium.nix

@@ -77,6 +77,9 @@
           "editor.formatOnType" = false;
         };
         "nix.formatterPath" = lib.getExe pkgs.nixfmt-rfc-style;
+        "nix.enableLanguageServer" = true;
+        "nix.serverPath" = lib.getExe pkgs.nixd;
+        "nix.serverSettings" = { };
         "editor.fontSize" = 13;
         "editor.fontWeight" = "normal";
         "git.detectSubmodulesLimit" = 30;