use system nixpkgs as registry

flake.nix

@@ -44,6 +44,7 @@
         config = { allowUnfree = true; };
       };
       lib = nixpkgs.lib;
+      specialArgs = { inherit inputs; };
       common_modules = [
         ./system/configuration.nix
         # nur.nixosModules.nur
@@ -68,20 +69,20 @@
     in {
       nixosConfigurations = {
         i15 = lib.nixosSystem {
-          inherit system;
+          inherit system specialArgs;
           modules = [ ./hosts/i15.nix ] ++ common_modules;
         };
         monolith = lib.nixosSystem {
-          inherit system;
+          inherit system specialArgs;
           modules = [ ./hosts/monolith.nix ./system/gitlab-runner.nix ]
             ++ common_modules;
         };
         rainbow = lib.nixosSystem {
-          inherit system;
+          inherit system specialArgs;
           modules = [ ./hosts/rainbow.nix ] ++ common_modules;
         };
         pixie = lib.nixosSystem {
-          inherit system;
+          inherit system specialArgs;
           modules = [ ./hosts/pixie.nix ] ++ common_modules ++ [{
             packages.media-packages.enable = lib.mkOverride 0 false;
             programs.steam.enable = lib.mkOverride 0 false;

system/configuration.nix

@@ -1,7 +1,7 @@
 # Edit this configuration file to define what should be installed on
 # your system.  Help is available in the configuration.nix(5) man page
 # and in the NixOS manual (accessible by running ‘nixos-help’).
-{ config, pkgs, ... }: {
+{ config, pkgs, inputs, ... }: {
   imports = [ ./media-packages.nix ];
   packages.media-packages.enable = true;
 
@@ -134,6 +134,8 @@
   # Or disable the firewall altogether.
   networking.firewall.enable = false;
   security.sudo.wheelNeedsPassword = false;
+
+  nix.registry.nixpkgs.flake = inputs.nixpkgs;
   nix = {
     settings = {
       auto-optimise-store = true;