anchor.diff:  
   {
     options = {
  +    system.checks.verifyNixPath = mkOption {
  +      type = types.bool;
  +      default = true;
  +      description = "Whether to run the NIX_PATH validation checks.";
  +    };
  +
  +    system.checks.text = mkOption {
  +      internal = true;
  +      type = types.lines;
  +      default = "";
  +    };
     };
   
     config = {
   
  +    system.checks.text = mkMerge [
  +      darwinChanges
  +      runLink
  +      (mkIf config.services.nix-daemon.enable buildUsers)
  +      nixStore
  +      (mkIf config.nix.gc.automatic nixGarbageCollector)
  +      nixChannels
  +      nixInstaller
  +      (mkIf cfg.verifyNixPath nixPath)
  +    ];
  +
       system.activationScripts.checks.text = ''
  -      ${darwinChanges}
  -      ${runLink}
  -      ${buildUsers}
  -      ${nixStore}
  -      ${nixGarbageCollector}
  -      ${nixChannels}
  -      ${nixInstaller}
  -      ${nixPath}
  +      ${cfg.text}
   
         if test ''${checkActivation:-0} -eq 1; then
           echo "ok" >&2
  
positive.code:     fi
    '';
  
    buildUsers = optionalString config.services.nix-daemon.enable ''
      buildUser=$(dscl . -read /Groups/nixbld GroupMembership 2>&1 | awk '/^GroupMembership: / {print $2}') || true
      if [ -z $buildUser ]; then
          echo "[1;31merror: Using the nix-daemon requires build users, aborting activation[0m" >&2
  
negative.code: with lib;
  
  let
    cfg = config.system.checks;
  
    darwinChanges = ''
      darwinChanges=/dev/null
      if test -e /run/current-system/darwin-changes; then
  