改结构

kernel/src/kernel/scene.ipp

@@ -24,6 +24,11 @@ struct Scene::Private : Prev_Private {
                        State_Access<State> pending_states,
                        const Prop* current_prop,
                        State_Access<State> current_states);
+    /* 写入事件统计字段表示开始新的统计窗口；累加器与发布 State 在同一入口归零。 */
+    template <typename Object, typename Owner, typename Member,
+              typename State_Type>
+    void before_state_set(Object* object, Member Owner::* member,
+                          State_Access<State_Type> pending_states);
     /* Private CRTP 入口：执行当前总 Taskflow；派生 Private 只有在替换完整 Scene 处理语义时才应覆盖。 */
     template <Attached Object, typename Callback>
     void process(Object* object, Callback&& callback) requires std::invocable<Callback, const Result&>;
@@ -36,6 +41,15 @@ struct Scene::Private : Prev_Private {
         requires std::invocable<Callback, const Result&>;
     /* 派生 Scene 的 Private 还可覆盖 Def::Private 的四个 State 生命周期 hook，并通过 State_Access::get<Tag>() 访问状态层。 */
 };
+
+template <typename Object, typename Owner, typename Member,
+          typename State_Type>
+void Scene::Private::before_state_set(
+    Object* object, Member Owner::* member,
+    State_Access<State_Type> pending_states) {
+    if constexpr (std::same_as<Owner, State>)
+        if (member == &State::event_statistics) event_statistics.reset();
+}
 struct Scene::Private::Runtime {
     std::unique_ptr<Task_Graph> taskflow; /* 当前已构建的总业务 DAG；为空表示尚未构建。 */
 };