anchor.diff:  { config, lib, pkgs, utils, ... }:
   with utils;
   with systemdUtils.unitOptions;
  -with lib; let
  -  cfg = config.systemd;
  +with lib;
   
  -  systemd = cfg.package;
  +let
  +  cfg = config.systemd.user;
  +
  +  systemd = config.systemd.package;
   
     inherit
       (systemdUtils.lib)
  
positive.code:     serviceToUnit
      socketToUnit
      timerToUnit
      pathToUnit
      ;
  
    upstreamUserUnits = [
      "app.slice"
  
negative.code:     ];
  
      environment.etc = {
        "systemd/user".source = generateUnits "user" cfg.units upstreamUserUnits [];
  
        "systemd/user.conf".text = ''
          [Manager]
          ${cfg.extraConfig}
        '';
      };
  
      systemd.user.units =
           mapAttrs' (n: v: nameValuePair "${n}.path"    (pathToUnit    n v)) cfg.paths
        // mapAttrs' (n: v: nameValuePair "${n}.service" (serviceToUnit n v)) cfg.services
        // mapAttrs' (n: v: nameValuePair "${n}.slice"   (sliceToUnit   n v)) cfg.slices
        // mapAttrs' (n: v: nameValuePair "${n}.socket"  (socketToUnit  n v)) cfg.sockets
        // mapAttrs' (n: v: nameValuePair "${n}.target"  (targetToUnit  n v)) cfg.targets
        // mapAttrs' (n: v: nameValuePair "${n}.timer"   (timerToUnit   n v)) cfg.timers;
  
      # Generate timer units for all services that have a ‘startAt’ value.
      systemd.user.timers =
  