a few more additions

hosts/common/global/nix.nix

@@ -18,10 +18,22 @@
       ];
       warn-dirty = false;
     };
-    gc = {
-      automatic = true;
-      options = "--delete-older-than 30d";
+    # GC is handled by `nh clean` below (keep-N / keep-since semantics).
+    # The two are mutually exclusive — nh asserts if nix.gc.automatic is on.
+    gc.automatic = false;
+  };
+
+  # nh: ergonomic nixos-rebuild wrapper. Auto-detects the target from the
+  # machine hostname (configs are named to match), so `nh os switch` needs
+  # no host arg. Runs as root, so its `clean` prunes system + user profiles.
+  programs.nh = {
+    enable = true;
+    flake = "/home/naps62/projects/nixos-config";
+    clean = {
+      enable = true;
+      extraArgs = "--keep 10 --keep-since 7d";
     };
   };
+
   nixpkgs.config.allowUnfree = true;
 }