{
  config,
  lib,
  pkgs,
  ...
}: let
  cfg = config.soispha.services.systemDiff;
in {
  options.soispha.services.systemDiff = {
    enable = lib.mkEnableOption "nvd run at system activation";
  };

  config = lib.mkIf cfg.enable {
    system.activationScripts.diff = {
      supportsDryActivation = true;
      text = ''
        PATH="${lib.makeBinPath [pkgs.nvd config.nix.package]}:$PATH"

        if [ -e /run/current-system ]; then
          # ${lib.getExe config.nix.package} --extra-experimental-features nix-command store diff-closures /run/current-system "$systemConfig"
          nvd diff $(ls -dv /nix/var/nix/profiles/system-*-link | tail -2)
        fi
      '';
    };
  };
}