pkgs,

      nix.package = pkgs.nixVersions.latest; # Use latest (includes nice S3 changes).

        options = "--delete-older-than 3d";

        options = "--delete-older-than 7d";

      }
      // optionalAttrs isServer {
        # Servers build and upload to S3 cache, so they can be more aggressive with GC.
        dates = "daily";
        options = "--delete-older-than 1d";