Move autoUpgrade back to flake.nix but use flake output instead of URL

Set autoUpgrade flake to current flake outpath but keeping nixpkgs
update, means things won't automatically be rolled back if there's no
internet connection. Keep using remote URL for server though to keep
unattended updates.

flake.nix

@@ -14,6 +14,7 @@
   };
 
   outputs = {
+    self,
     nixpkgs,
     home-manager,
     stylix,
@@ -42,7 +43,11 @@
             ./hosts/${hostName}/configuration.nix
             ./hosts/${hostName}/hardware-configuration.nix
             ./system/default.nix
-            ({pkgs, ...}: {
+            ({
+              lib,
+              pkgs,
+              ...
+            }: {
               nix = {
                 enable = true;
                 settings = {
@@ -66,9 +71,22 @@
                 '';
               };
               nixpkgs.config.allowUnfree = true;
-              system = {inherit stateVersion;};
               networking = {inherit hostName;};
               programs.${shell}.enable = true;
+              system = {
+                inherit stateVersion;
+                autoUpgrade = {
+                  enable = true;
+                  flake = lib.mkDefault self.outPath;
+                  flags = [
+                    "--update-input"
+                    "nixpkgs"
+                    "--no-write-lock-file"
+                    "-L" # print build logs
+                  ];
+                  dates = "02:00";
+                };
+              };
               users = {
                 defaultUserShell = pkgs.${shell};
                 users = let
@@ -139,7 +157,6 @@
         systemConfig {
           inherit hostName user system;
           systemModules = [
-            ./system/autoupgrade.nix
             ./services/caddy.nix
             ./services/gitea.nix
             ./services/grafana.nix
@@ -147,7 +164,9 @@
             ./services/sshd.nix
             ./services/syncthing.nix
           ];
-          homeModules = [./home/default.nix];
+          homeModules = [
+            ./home/default.nix
+          ];
         };
 
       ## Personal
@@ -164,7 +183,9 @@
             ./system/hyprland.nix
             ./system/games.nix
           ];
-          homeModules = [./home/hyprland/default.nix];
+          homeModules = [
+            ./home/hyprland/default.nix
+          ];
         };
 
       Vanguard = let
@@ -175,11 +196,12 @@
         systemConfig {
           inherit hostName user system;
           systemModules = [
-            ./system/autoupgrade.nix
             ./system/hyprland.nix
             ./system/games.nix
           ];
-          homeModules = [./home/hyprland/default.nix];
+          homeModules = [
+            ./home/hyprland/default.nix
+          ];
         };
 
       ## Work
@@ -195,7 +217,9 @@
             ./system/laptop.nix
             ./system/hyprland.nix
           ];
-          homeModules = [./home/hyprland/default.nix];
+          homeModules = [
+            ./home/hyprland/default.nix
+          ];
         };
 
       Scorch = let
@@ -206,10 +230,11 @@
         systemConfig {
           inherit hostName user system;
           systemModules = [
-            ./system/autoupgrade.nix
             ./system/hyprland.nix
           ];
-          homeModules = [./home/hyprland/default.nix];
+          homeModules = [
+            ./home/hyprland/default.nix
+          ];
         };
     };
   };

hosts/Legion/configuration.nix

@@ -1,6 +1,7 @@
-{...}: {
+{config, ...}: {
   users.mutableUsers = false;
   system.autoUpgrade = {
+    flake = "git+${config.nix.registry.nixos.to.url}";
     randomizedDelaySec = "15min";
     allowReboot = true;
     rebootWindow = {

system/autoupgrade.nix

@@ -1,15 +0,0 @@
-{config, ...}: let
-  flakeURL = config.nix.registry.nixos.to.url;
-in {
-  system.autoUpgrade = {
-    enable = true;
-    flake = "git+${flakeURL}";
-    flags = [
-      "--update-input"
-      "nixpkgs"
-      "--no-write-lock-file"
-      "-L" # print build logs
-    ];
-    dates = "02:00";
-  };
-}