fix: ignore stale callbacks from rescheduled timers

- Add generation counters to SmartCondition and EventSensor timers.
- Preserve pending changes and the retention period when timers are restarted.
- Silently cancel timers that have already expired.
- Add regression tests for stale callbacks and expiry during cancellation.

virtualsensors.py

@@ -757,20 +757,28 @@ class EventSensor(VirtualSensorBase):
 
         self.retain_time = self.yaml_block['retain_time']
         self.cb_handle = None
+        self._timer_generation = 0
 
         self.event_handlers = []
         if "activation_events" in self.yaml_block:
             self.event_handlers.append(EventHandler(self.ad_api, self.yaml_block["activation_events"], self.on_activation_event,logger_interface = self.logger_interface))
         
     def on_activation_event(self, event_name, data, kwargs):
+        self._timer_generation += 1
         self.output_sensor.set_state(state = 'on')
         if self.cb_handle is not None:
-            self.ad_api.cancel_timer(self.cb_handle)
-        self.cb_handle = self.ad_api.run_in(self.on_retain_time_elapsed, self.retain_time)
+            self.ad_api.cancel_timer(self.cb_handle, silent=True)
+        self.cb_handle = self.ad_api.run_in(
+            self.on_retain_time_elapsed, self.retain_time,
+            generation=self._timer_generation,
+        )
 
     def on_retain_time_elapsed(self, kwargs):
-        self.output_sensor.set_state(state = 'off')
+        # Cancellation cannot retract a callback already queued by AppDaemon.
+        if kwargs.get('generation') != self._timer_generation:
+            return
         self.cb_handle = None
+        self.output_sensor.set_state(state = 'off')
 
     def generate_sensor_name(self,virtual_sensor_name):
         return f"binary_sensor.{virtual_sensor_name}"