[core] Freshen loop_component_start_time_ before scheduler dispatch

esphome/core/application.h

@@ -103,6 +103,12 @@ class Application {
   void set_current_component(Component *component) { this->current_component_ = component; }
   Component *get_current_component() { return this->current_component_; }
 
+  /// Update the cached loop component start time. Used by the scheduler before
+  /// dispatching a queued callback so callers reading
+  /// get_loop_component_start_time() inside the callback observe a fresh value
+  /// instead of one inherited from the prior loop iteration's last component.
+  void set_loop_component_start_time(uint32_t now) { this->loop_component_start_time_ = now; }
+
 // Entity register methods (generated from entity_types.h).
 // Each entity type gets two overloads:
 //   - register_<entity>(obj)                              — bare push_back

esphome/core/scheduler.cpp

@@ -772,6 +772,11 @@ Scheduler::SchedulerItem *HOT Scheduler::pop_raw_locked_() {
 // Helper to execute a scheduler item
 uint32_t HOT Scheduler::execute_item_(SchedulerItem *item, uint32_t now) {
   App.set_current_component(item->component);
+  // Freshen the cached loop component start time so callbacks reading
+  // App.get_loop_component_start_time() observe the dispatch time of this
+  // item rather than a stale value from the prior loop iteration's last
+  // component phase.
+  App.set_loop_component_start_time(now);
   WarnIfComponentBlockingGuard guard{item->component, now};
   item->callback();
   uint32_t end = guard.finish();