v0.16.5

docs/API.md

@@ -606,6 +606,14 @@ Important rules:
 
 The returned `Zone` also contains runtime state including sensor readings, resolved/effective setpoints, demand, current preset, manual overrides, local Quick Thermostat ownership, temporary session state, device-manual takeover, control owner/source/reason, lockout timestamps and `created_at`/`updated_at`.
 
+Temperature diagnostics in `GET /api/zones` and zone WebSocket updates:
+
+- `control_temperature_source`: `device`, `external`, `combined`, `device_fallback`, `device_discrepancy_fallback`, `unavailable`.
+- `room_sensor_status`: `not_used`, `ok`, `stale`, `error`, `discrepancy` (empty until the first cycle on older persisted zones).
+- `heating_sensor_guard_active`: `true` when the thermostat would otherwise fall back to GREE while an automatic heating zone is configured for a Home Assistant room sensor. Automatic heating is paused, pending starts are cancelled, and existing automatic heat is switched OFF when compressor protection permits. The guard clears automatically with a valid room reading. Explicit manual control and GREE-only heating are unchanged.
+
+For a `combined` sensor strategy, the displayed control temperature is GREE × (1 − `external_sensor_weight`) + room × `external_sensor_weight`, rounded to 0.1°C, unless the difference exceeds `max_sensor_difference`. The Web UI provides this explanation in the zone and thermostat temperature help. Home Assistant sample freshness prefers `last_reported` when supplied and otherwise uses `last_updated`.
+
 ### `GET /api/zones`
 
 Returns `Zone[]`.