rest of the split migration

modules/dev/ruby/home.nix

@@ -0,0 +1,39 @@
+{
+  config,
+  inputs,
+  lib,
+  osConfig ? null,
+  pkgs,
+  ...
+}:
+let
+  hm = inputs.self.lib.hmModule {
+    inherit
+      config
+      inputs
+      osConfig
+      ;
+    optionPath = [
+      "dev"
+      "ruby"
+    ];
+  };
+  cfg = config.my.dev.ruby;
+  feature = import ./common.nix { inherit pkgs; };
+in
+{
+  options.my.dev.ruby.enable = lib.mkEnableOption "Install Ruby tooling globally";
+  config = lib.mkMerge [
+    {
+      my.dev.ruby.enable = lib.mkDefault hm.enabledByDefault;
+    }
+    (lib.mkIf cfg.enable {
+      home.packages = feature.packages;
+      home.sessionVariables = {
+        GEM_HOME = "${config.xdg.dataHome}/ruby/gems";
+        GEM_PATH = "${config.xdg.dataHome}/ruby/gems";
+        GEM_SPEC_CACHE = "${config.xdg.dataHome}/ruby/specs";
+      };
+    })
+  ];
+}