pass channel info to hosts as channel specialArg

systemFlake.nix

@@ -87,12 +87,17 @@ let
       selectedNixpkgs = getNixpkgs host;
       host = evalHostArgs (mergeAny hostDefaults host');
       patchedChannel = selectedNixpkgs.path;
+      channel = channels.${host.channelName} // { name = host.channelName; };
+
+      specialArgs = host.specialArgs // { inherit channel; };
+
+      /* nixos specific arguments */
       # Use lib from patched nixpkgs
       lib = selectedNixpkgs.lib;
       # Use nixos modules from patched nixpkgs
       baseModules = import (patchedChannel + "/nixos/modules/module-list.nix");
       # Override `modulesPath` because otherwise imports from there will not use patched nixpkgs
-      specialArgs = { modulesPath = builtins.toString (patchedChannel + "/nixos/modules"); } // host.specialArgs;
+      nixosSpecialArgs = { modulesPath = builtins.toString (patchedChannel + "/nixos/modules"); };
       # The only way to find out if a host has `nixpkgs.config` set to
       # the non-default value is by evalling most of the config.
       hostConfig = (lib.evalModules {
@@ -149,9 +154,10 @@ let
             ];
           })
         ] ++ host.modules;
-        specialArgs = host.specialArgs;
+        inherit specialArgs;
       } // (optionalAttrs (host.output == "nixosConfigurations") {
-        inherit lib baseModules specialArgs;
+        inherit lib baseModules;
+        specialArgs = nixosSpecialArgs // specialArgs;
       }));
     }
   );