Working version

coordinator.py

@@ -0,0 +1,48 @@
+"""DataUpdateCoordinator for Modbus RTU Monitor."""
+
+from __future__ import annotations
+
+import logging
+from typing import TYPE_CHECKING
+
+from homeassistant.helpers.update_coordinator import DataUpdateCoordinator
+
+from .const import DOMAIN, SlaveData
+
+if TYPE_CHECKING:
+    from homeassistant.config_entries import ConfigEntry
+    from homeassistant.core import HomeAssistant
+
+    from .hub import ModbusRTUMonitorHub
+
+_LOGGER = logging.getLogger(__name__)
+
+
+class ModbusRTUMonitorCoordinator(DataUpdateCoordinator[dict[int, SlaveData]]):
+    """Coordinator for Modbus RTU Monitor state updates."""
+
+    def __init__(
+        self,
+        hass: HomeAssistant,
+        config_entry: ConfigEntry,
+        hub: ModbusRTUMonitorHub,
+    ) -> None:
+        """Initialize coordinator."""
+        self.hub = hub
+
+        # No update_interval - updates come from passive monitoring
+        super().__init__(
+            hass,
+            _LOGGER,
+            config_entry=config_entry,
+            name=DOMAIN,
+            update_interval=None,  # Push-based updates
+        )
+
+    async def _async_update_data(self) -> dict[int, SlaveData]:
+        """Not used - data comes from passive monitoring.
+
+        This method won't be called due to update_interval=None.
+        Updates happen via hub calling async_set_updated_data().
+        """
+        return self.hub.discovered_slaves