state version pass thru option

home.nix

@@ -8,15 +8,7 @@
   # manage.
   home.username = config.user;
   home.homeDirectory = "/home/${config.user}";
-
-  # This value determines the Home Manager release that your configuration is
-  # compatible with. This helps avoid breakage when a new Home Manager release
-  # introduces backwards incompatible changes.
-  #
-  # You should not change this value, even if you update Home Manager. If you do
-  # want to update the value, then make sure to first check the Home Manager
-  # release notes.
-  home.stateVersion = "25.05"; # Please read the comment before changing.
+  home.stateVersion = config.stateVersion;
 
   # The home.packages option allows you to install Nix packages into your
   # environment.

options.nix

@@ -6,6 +6,19 @@
     description = "The username for the Home Manager configuration.";
   };
 
+  # This value determines the Home Manager release that your configuration is
+  # compatible with. This helps avoid breakage when a new Home Manager release
+  # introduces backwards incompatible changes.
+  #
+  # You should not change this value, even if you update Home Manager. If you do
+  # want to update the value, then make sure to first check the Home Manager
+  # release notes.
+  options.stateVersion = lib.mkOption {
+    type = lib.types.str;
+    default = "25.05";
+    description = "The state version when the configuration was initially created";
+  };
+
   options.profile = lib.mkOption {
     type = lib.types.enum [ "personal" "work" ];
     default = "personal";