Fixes #38986 - Support runtime evaluation of Procs in plugin metadata

Allow plugins to register metadata as lambdas that are evaluated at runtime
instead of at registration time. This enables dynamic state changes without
requiring a server restart.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: jeremylenz

app/helpers/application_helper.rb

@@ -423,9 +423,8 @@ def core_app_metadata
   end
 
   def app_metadata
-    core_app_metadata.merge(
-      ::Foreman::Plugin.app_metadata_registry.all_plugin_metadata
-    )
+    ::Foreman::Plugin::AppMetadataRegistry.resolve_procs(core_app_metadata)
+      .merge(::Foreman::Plugin.app_metadata_registry.all_plugin_metadata_resolved)
   end
 
   def ui_settings

app/registries/foreman/plugin/app_metadata_registry.rb

@@ -17,6 +17,18 @@ def register(plugin_name, data = {})
       def all_plugin_metadata
         @plugin_metadata
       end
+
+      def all_plugin_metadata_resolved
+        @plugin_metadata.transform_values { |v| self.class.resolve_procs(v) }
+      end
+
+      # Evaluates any Proc values in the given hash, calling them and replacing
+      # them with their return values. All other values remain unchanged.
+      # @param hash [Hash] A hash potentially containing Proc values
+      # @return [Hash] A new hash with Procs evaluated
+      def self.resolve_procs(hash)
+        hash.transform_values { |v| v.is_a?(Proc) ? v.call : v }
+      end
     end
   end
 end

test/helpers/application_helper_test.rb

@@ -133,4 +133,69 @@ def test_generate_link_for
       assert_equal "/new/hosts/#{@host.id}", result
     end
   end
+
+  describe 'app_metadata and evaluate_metadata_hash' do
+    test 'app_metadata returns hash with core and plugin metadata' do
+      result = app_metadata
+
+      assert_kind_of Hash, result
+      assert result.key?(:version)
+      assert result.key?(:UISettings)
+    end
+
+    test 'app_metadata evaluates lambda values in plugin metadata' do
+      counter = 0
+      ::Foreman::Plugin.app_metadata_registry.register(:test_plugin, {
+        dynamic: -> { counter += 1 },
+      })
+
+      metadata = app_metadata
+      result1 = metadata['test_plugin']['dynamic']
+      result2 = app_metadata['test_plugin']['dynamic']
+
+      assert_equal 1, result1
+      assert_equal 2, result2
+    ensure
+      # Clean up test registration
+      ::Foreman::Plugin.app_metadata_registry.instance_variable_get(:@plugin_metadata).delete(:test_plugin)
+    end
+
+    test 'app_metadata preserves static values' do
+      ::Foreman::Plugin.app_metadata_registry.register(:test_plugin_static, {
+        static_string: 'test',
+        static_number: 42,
+        static_bool: true,
+      })
+
+      result = app_metadata['test_plugin_static']
+
+      assert_equal 'test', result['static_string']
+      assert_equal 42, result['static_number']
+      assert_equal true, result['static_bool']
+    ensure
+      ::Foreman::Plugin.app_metadata_registry.instance_variable_get(:@plugin_metadata).delete(:test_plugin_static)
+    end
+
+    test 'app_metadata handles mixed static and lambda values' do
+      call_count = 0
+      ::Foreman::Plugin.app_metadata_registry.register(:test_plugin_mixed, {
+        static: 'static_value',
+        dynamic: lambda {
+                   call_count += 1
+                   "dynamic_#{call_count}"
+                 },
+      })
+
+      result = app_metadata['test_plugin_mixed']
+
+      assert_equal 'static_value', result['static']
+      assert_equal 'dynamic_1', result['dynamic']
+
+      # Second call should re-evaluate lambda
+      result2 = app_metadata['test_plugin_mixed']
+      assert_equal 'dynamic_2', result2['dynamic']
+    ensure
+      ::Foreman::Plugin.app_metadata_registry.instance_variable_get(:@plugin_metadata).delete(:test_plugin_mixed)
+    end
+  end
 end