fix

modules/system/gc.nix

@@ -0,0 +1,10 @@
+_: {
+  nix.gc = {
+    automatic = true;
+    dates = "daily";
+    options = "--delete-older-than 7d";
+  };
+
+  nix.settings.auto-optimise-store = true;
+  nix.optimise.automatic = true;
+}