Rework on Google Assistant doorbell support (#100930)

* Rework on Google Assistant doorbell event

* Additional comment on syncing notificatiions

* Update homeassistant/components/google_assistant/trait.py

* Only sync event if state attr changed

* Update comment

homeassistant/components/google_assistant/helpers.py

@@ -240,7 +240,7 @@ class AbstractConfig(ABC):
     async def async_sync_notification(
         self, agent_user_id: str, event_id: str, payload: dict[str, Any]
     ) -> HTTPStatus:
-        """Sync notification to Google."""
+        """Sync notifications to Google."""
         # Remove any pending sync
         self._google_sync_unsub.pop(agent_user_id, lambda: None)()
         status = await self.async_report_state(payload, agent_user_id, event_id)

homeassistant/components/google_assistant/report_state.py

@@ -80,7 +80,15 @@ def async_enable_report_state(hass: HomeAssistant, google_config: AbstractConfig
         ):
             return
 
-        if (notifications := entity.notifications_serialize()) is not None:
+        # We only trigger notifications on changes in the state value, not attributes.
+        # This is mainly designed for our event entity types
+        # We need to synchronize notifications using a `SYNC` response,
+        # together with other state changes.
+        if (
+            old_state
+            and old_state.state != new_state.state
+            and (notifications := entity.notifications_serialize()) is not None
+        ):
             event_id = uuid4().hex
             payload = {
                 "devices": {"notifications": {entity.state.entity_id: notifications}}

homeassistant/components/google_assistant/trait.py

@@ -382,10 +382,14 @@ class ObjectDetection(_Trait):
             return None
 
         # Only notify if last event was less then 30 seconds ago
-        time_stamp = datetime.fromisoformat(self.state.state)
+        time_stamp: datetime = datetime.fromisoformat(self.state.state)
         if (utcnow() - time_stamp) > timedelta(seconds=30):
             return None
 
+        # A doorbell event is treated as an object detection of 1 unclassified object.
+        # The implementation follows the pattern from the Smart Home Doorbell Guide:
+        # https://developers.home.google.com/cloud-to-cloud/guides/doorbell
+        # The detectionTimestamp is the time in ms from January 1, 1970, 00:00:00 (UTC)
         return {
             "ObjectDetection": {
                 "objects": {

tests/components/google_assistant/test_trait.py

@@ -223,7 +223,7 @@ async def test_onoff_input_boolean(hass: HomeAssistant) -> None:
 
 @pytest.mark.freeze_time("2023-08-01T00:02:57+00:00")
 async def test_doorbell_event(hass: HomeAssistant) -> None:
-    """Test doorbell event trait support for input_boolean domain."""
+    """Test doorbell event trait support for event domain."""
     assert trait.ObjectDetection.supported(event.DOMAIN, 0, "doorbell", None)
 
     state = State(