Add flake app to update primary inputs

lib.nix

@@ -56,10 +56,8 @@
   };
 
   perSystem = { system, pkgs, lib, ... }: {
-    # A rough app for activating the system locally.
-    #
-    # TODO: Replace with deploy-rs or (new) nixinate
-    apps.activate =
+    # TODO: replace these with mission-control
+    apps =
       let
         # Create a flake app that wraps the given bash CLI.
         bashCmdApp = name: cmd: {
@@ -74,14 +72,27 @@
             }) + "/bin/${name}";
         };
       in
-      if system == "aarch64-darwin" then
-        bashCmdApp "darwin" ''
-          ${self.darwinConfigurations.default.system}/sw/bin/darwin-rebuild \
-            switch --flake ${self}#default
-        ''
-      else
-        bashCmdApp "linux" ''
-          ${lib.getExe pkgs.nixos-rebuild} --use-remote-sudo switch -j auto
-        '';
+      {
+        # A rough app for activating the system locally.
+        #
+        # TODO: Replace with deploy-rs or (new) nixinate
+        activate =
+          if system == "aarch64-darwin" then
+            bashCmdApp "darwin" ''
+              ${self.darwinConfigurations.default.system}/sw/bin/darwin-rebuild \
+              switch --flake ${self}#default
+            ''
+          else
+            bashCmdApp "linux" ''
+              ${lib.getExe pkgs.nixos-rebuild} --use-remote-sudo switch -j auto
+            '';
+
+        update-primary =
+          let inputs = [ "nixpkgs" "home-manager" "darwin" ];
+          in bashCmdApp "update-primary" ''
+            nix flake lock ${lib.foldl' (acc: x: acc + " --update-input " + x) "" inputs}
+          '';
+
+      };
   };
 }