M5-T11: add HA discovery and state publishing wired to polling

app/services/modbus_poll.py

@@ -31,6 +31,7 @@ from app.config import Settings
 from app.integrations.modbus import driver, profiles
 from app.models.modbus import ModbusDevice, ModbusReading
 from app.services.config_page import build_runtime_settings
+from app.services.ha_discovery import publish_device_offline, publish_device_state
 
 logger = logging.getLogger(__name__)
 
@@ -84,6 +85,19 @@ def poll_device(session: Session, device: ModbusDevice) -> ModbusReading | None:
             len(payload),
             now.isoformat(),
         )
+
+        # Best-effort: push MQTT state after successful poll.
+        # Must never let MQTT errors crash the poll loop.
+        try:
+            publish_device_state(session, device)
+        except Exception:  # noqa: BLE001
+            logger.exception(
+                "poll_device: MQTT state publish failed for device %r (id=%d); "
+                "continuing (poll itself succeeded)",
+                device.friendly_name,
+                device.id,
+            )
+
         return reading
 
     except Exception:  # noqa: BLE001
@@ -115,6 +129,17 @@ def poll_device(session: Session, device: ModbusDevice) -> ModbusReading | None:
             logger.exception(
                 "Also failed to persist last_poll_ok=False for device id=%d", device.id
             )
+
+        # Best-effort: publish "offline" availability after failed poll.
+        try:
+            publish_device_offline(device.uuid)
+        except Exception:  # noqa: BLE001
+            logger.exception(
+                "poll_device: MQTT offline publish failed for device %r (id=%d)",
+                device.friendly_name,
+                device.id,
+            )
+
         return None