Update sub-component batteries from parent HA entity in poller and live sync

tests/test_ha_integration.py

@@ -182,6 +182,37 @@ def test_poll_updates_installed_batteries(ha_app, ha_client_f):
     mock_ha.get_state.assert_called_once_with("sensor.dev_a_battery")
 
 
+def test_poll_updates_batteries_in_subcomponents(ha_app, ha_client_f):
+    """Batteries installed in sub-components are updated via the parent's HA entity."""
+    ha_client_f.post("/device/add", data={"name": "RC Set", "battery_slots": "0", "battery_size": ""})
+    ha_client_f.post("/device/add", data={"name": "Remote", "battery_slots": "2",
+                                          "battery_size": "AA", "parent_id": "1"})
+    ha_client_f.post("/battery/add", data={"brand": "X", "count": "1", "size": "AA"})
+    ha_client_f.post("/battery/1/assign", data={"device_id": "2"})
+    ha_client_f.post("/device/1/edit", data={
+        "name": "RC Set", "battery_slots": "0", "battery_size": "",
+        "ha_entity_id": "sensor.rc_set_battery"
+    })
+
+    from ha_client import HomeAssistantClient
+    from ha_poller import HaPoller
+    from models import Battery, BatteryPctLog
+
+    mock_ha = MagicMock(spec=HomeAssistantClient)
+    mock_ha.enabled = True
+    mock_ha.get_state.return_value = 37
+
+    Session = _make_session_factory(ha_app)
+    HaPoller(mock_ha, Session, interval=300)._poll_once()
+
+    s = Session()
+    b = s.get(Battery, 1)
+    assert b.battery_percentage == 37
+    logs = s.query(BatteryPctLog).filter_by(battery_id=1, source="poll").all()
+    assert len(logs) == 1 and logs[0].percentage == 37
+    s.close()
+
+
 def test_poll_skips_uninstalled_batteries(ha_app, ha_client_f):
     """Batteries that are available (not installed) are not updated by the poller."""
     ha_client_f.post("/device/add", data={"name": "Dev B", "battery_slots": "1", "battery_size": "AA"})