Refactor BLE layer for 24/7 reliability

- Replace raw BleakClient with establish_connection from
  bleak-retry-connector (retries, GATT service cache, proxy-aware)
- Replace fragile asyncio.Event with asyncio.Queue for response frames,
  drain stale data on each connection to prevent cross-cycle leakage
- Register BLE advertisement callback to keep BLEDevice reference fresh
  across ESPHome proxy path changes
- Remove asyncio.sleep(2) device lookup hack
- Increase poll timeout floor from 10s to 20s
- Increase failure tolerance from 3 to 5 consecutive misses
- Bump default poll interval to 30s, min to 15s (halves connection churn)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

custom_components/xiaoxiang_bms/__init__.py

@@ -1,8 +1,15 @@
 """Xiaoxiang Smart BMS — Home Assistant integration."""
 from __future__ import annotations
 
+from homeassistant.components.bluetooth import (
+    BluetoothChange,
+    BluetoothScanningMode,
+    BluetoothServiceInfoBleak,
+    async_register_callback,
+)
+from homeassistant.components.bluetooth.match import ADDRESS, BluetoothCallbackMatcher
 from homeassistant.config_entries import ConfigEntry
-from homeassistant.core import HomeAssistant
+from homeassistant.core import HomeAssistant, callback
 
 from .const import CONF_ADDRESS, CONF_POLL_INTERVAL, DEFAULT_POLL_INTERVAL, DOMAIN
 from .coordinator import BmsCoordinator
@@ -16,13 +23,31 @@ async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
     poll_interval = entry.options.get(CONF_POLL_INTERVAL, DEFAULT_POLL_INTERVAL)
 
     coordinator = BmsCoordinator(hass, address, poll_interval, name=entry.title)
+
+    # Keep the coordinator's BLE device reference fresh via advertisement callback.
+    # This avoids stale transport paths when ESPHome proxies cycle.
+    @callback
+    def _async_update_ble(
+        service_info: BluetoothServiceInfoBleak,
+        change: BluetoothChange,
+    ) -> None:
+        coordinator._ble_device = service_info.device
+
+    entry.async_on_unload(
+        async_register_callback(
+            hass,
+            _async_update_ble,
+            BluetoothCallbackMatcher({ADDRESS: address}),
+            BluetoothScanningMode.PASSIVE,
+        )
+    )
+
     await coordinator.async_setup()
     await coordinator.async_config_entry_first_refresh()
 
     hass.data.setdefault(DOMAIN, {})[entry.entry_id] = coordinator
     await hass.config_entries.async_forward_entry_setups(entry, PLATFORMS)
 
-    # Reload the entry when options (e.g. poll interval) change
     entry.async_on_unload(entry.add_update_listener(_async_update_listener))
 
     return True

custom_components/xiaoxiang_bms/bluetooth_handler.py

@@ -5,8 +5,9 @@ import asyncio
 import logging
 import struct
 
-from bleak import BleakClient, BleakError
+from bleak import BleakError
 from bleak.backends.device import BLEDevice
+from bleak_retry_connector import establish_connection, BleakClientWithServiceCache
 
 from .const import (
     FRAME_END,
@@ -19,7 +20,7 @@ _LOGGER = logging.getLogger(__name__)
 
 # Full frame layout:
 #   [0xDD] [CMD] [STATUS] [PAYLOAD_LEN] [PAYLOAD...] [CHK_HI] [CHK_LO] [0x77]
-#   Header = 4 bytes, trailer = 3 bytes (checksum × 2 + end marker)
+#   Header = 4 bytes, trailer = 3 bytes (checksum x 2 + end marker)
 _HEADER_LEN = 4
 _TRAILER_LEN = 3
 
@@ -27,7 +28,7 @@ _TRAILER_LEN = 3
 class BmsBluetoothHandler:
     """Protocol framing and parsing for a Xiaoxiang BMS device.
 
-    Designed for a connect → poll → disconnect pattern: the BMS only allows
+    Designed for a connect -> poll -> disconnect pattern: the BMS only allows
     one simultaneous BLE connection, so we hold it only for the duration of
     a single data fetch and release it immediately after.
     """
@@ -35,9 +36,24 @@ class BmsBluetoothHandler:
     def __init__(self, address: str) -> None:
         self._address = address
         self._buffer = bytearray()
-        self._response_event = asyncio.Event()
+        self._response_queue: asyncio.Queue[bytes] = asyncio.Queue()
-        self._response_data: bytes | None = None
+
-        self._lock = asyncio.Lock()
+    # ------------------------------------------------------------------
+    # Internal helpers
+    # ------------------------------------------------------------------
+
+    def _drain_queue(self) -> None:
+        """Discard any stale frames left in the queue from a prior cycle."""
+        while not self._response_queue.empty():
+            try:
+                self._response_queue.get_nowait()
+            except asyncio.QueueEmpty:
+                break
+
+    def _reset(self) -> None:
+        """Clear all transient state before a new connection."""
+        self._buffer.clear()
+        self._drain_queue()
 
     # ------------------------------------------------------------------
     # High-level poll — the only entry point the coordinator needs
@@ -47,7 +63,7 @@ class BmsBluetoothHandler:
         self,
         ble_device: BLEDevice,
         commands: list[bytes],
-        timeout: float = 3.0,
+        timeout: float = 5.0,
         retries: int = 3,
     ) -> list[bytes | None]:
         """Connect, send each command in sequence, disconnect.
@@ -56,13 +72,17 @@ class BmsBluetoothHandler:
         only during the active read window and disconnecting immediately after,
         the mobile app (or any other client) can connect freely between polls.
         """
+        self._reset()
         _LOGGER.debug("Polling BMS at %s", self._address)
-        client = BleakClient(ble_device)
+
+        client = await establish_connection(
+            BleakClientWithServiceCache,
+            ble_device,
+            self._address,
+            max_attempts=3,
+        )
         try:
-            await client.connect()
             await client.start_notify(RX_CHAR_UUID, self._on_notify)
-            # Give the BMS a moment to register the subscription before
-            # we start sending commands
             await asyncio.sleep(0.3)
             return [
                 await self._request(client, cmd, timeout, retries)
@@ -71,9 +91,8 @@ class BmsBluetoothHandler:
         finally:
             try:
                 await client.disconnect()
-            except Exception:
+            except BleakError:
                 pass
-            self._buffer.clear()
 
     # ------------------------------------------------------------------
     # Frame reception
@@ -115,8 +134,7 @@ class BmsBluetoothHandler:
             return
 
         _LOGGER.debug("BMS frame received (cmd=0x%02X, len=%d)", frame[1], payload_len)
-        self._response_data = frame
+        self._response_queue.put_nowait(frame)
-        self._response_event.set()
 
     # ------------------------------------------------------------------
     # Request / response (private — used inside poll())
@@ -124,7 +142,7 @@ class BmsBluetoothHandler:
 
     async def _request(
         self,
-        client: BleakClient,
+        client: BleakClientWithServiceCache,
         command: bytes,
         timeout: float,
         retries: int,
@@ -134,30 +152,33 @@ class BmsBluetoothHandler:
         Tries Write With Response first; falls back to Write Without Response
         if the characteristic rejects it — covers both BMS firmware variants.
         """
-        async with self._lock:
         for attempt in range(1, retries + 1):
-                self._response_event.clear()
+            # Drain any stale frames before sending a new command
-                self._response_data = None
+            self._drain_queue()
+            self._buffer.clear()
+
             try:
                 await client.write_gatt_char(TX_CHAR_UUID, command, response=True)
             except BleakError:
                 try:
                     await client.write_gatt_char(TX_CHAR_UUID, command, response=False)
                 except BleakError as exc:
-                        _LOGGER.error("BLE write failed (attempt %d/%d): %s",
+                    _LOGGER.warning("BLE write failed (attempt %d/%d): %s",
                                     attempt, retries, exc)
                     if attempt < retries:
-                            await asyncio.sleep(0.3)
+                        await asyncio.sleep(0.5)
                     continue
 
             try:
-                    await asyncio.wait_for(self._response_event.wait(), timeout)
+                frame = await asyncio.wait_for(
-                    return self._response_data
+                    self._response_queue.get(), timeout
+                )
+                return frame
             except asyncio.TimeoutError:
                 _LOGGER.warning("BMS timeout (cmd=0x%s, attempt %d/%d)",
                                 command.hex(), attempt, retries)
                 if attempt < retries:
-                        await asyncio.sleep(0.3)
+                    await asyncio.sleep(0.5)
 
         return None
 
@@ -168,25 +189,29 @@ class BmsBluetoothHandler:
     async def write_mos(self, ble_device: BLEDevice, value: int) -> bool:
         """Send a MOS control write command and return True on ACK.
 
-        Follows the same connect → send → disconnect pattern as poll() so
+        Follows the same connect -> send -> disconnect pattern as poll() so
         it doesn't interfere with the normal poll cycle.
         """
+        self._reset()
         command = self._build_mos_command(value)
         _LOGGER.debug("Writing MOS value 0x%02X to BMS at %s", value, self._address)
-        client = BleakClient(ble_device)
+
+        client = await establish_connection(
+            BleakClientWithServiceCache,
+            ble_device,
+            self._address,
+            max_attempts=3,
+        )
         try:
-            await client.connect()
             await client.start_notify(RX_CHAR_UUID, self._on_notify)
-            await asyncio.sleep(0.5)
+            await asyncio.sleep(0.3)
-            response = await self._request(client, command, timeout=3.0, retries=2)
+            response = await self._request(client, command, timeout=5.0, retries=2)
-            # Response: DD E1 00 00 CHK_H CHK_L 77  (status byte 0x00 = OK)
             return response is not None and response[2] == 0x00
         finally:
             try:
                 await client.disconnect()
-            except Exception:
+            except BleakError:
                 pass
-            self._buffer.clear()
 
     @staticmethod
     def _build_mos_command(value: int) -> bytes:
@@ -198,7 +223,7 @@ class BmsBluetoothHandler:
         Checksum = two's complement of sum, high byte first.
 
         Verified against spec example:
-          XX=0x02 → sum=0xE5 → ~0xE5+1=0xFF1B → CHK FF 1B ✓
+          XX=0x02 -> sum=0xE5 -> ~0xE5+1=0xFF1B -> CHK FF 1B
         """
         checked = [0xE1, 0x02, 0x00, value & 0xFF]
         checksum = (~sum(checked) + 1) & 0xFFFF
@@ -217,10 +242,10 @@ class BmsBluetoothHandler:
         """Parse a 0x03 general info response frame.
 
         Payload byte offsets (frame[4] is payload[0]):
-          0-1   Total voltage      uint16 BE  ÷100 → V
+          0-1   Total voltage      uint16 BE  /100 -> V
-          2-3   Current            int16  BE  ÷100 → A  (positive = charging, negative = discharging)
+          2-3   Current            int16  BE  /100 -> A  (positive = charging, negative = discharging)
-          4-5   Residual capacity  uint16 BE  ÷100 → Ah
+          4-5   Residual capacity  uint16 BE  /100 -> Ah
-          6-7   Nominal capacity   uint16 BE  ÷100 → Ah
+          6-7   Nominal capacity   uint16 BE  /100 -> Ah
           8-9   Cycle count        uint16 BE
           10-11 Production date    (ignored)
           12-15 Balance status     (ignored)
@@ -230,7 +255,7 @@ class BmsBluetoothHandler:
           20    MOS status         uint8
           21    Cell count         uint8
           22    Temp probe count   uint8
-          23+   Temperatures       uint16 BE each  (raw − 2731) ÷ 10 → °C
+          23+   Temperatures       uint16 BE each  (raw - 2731) / 10 -> C
         """
         p = frame[_HEADER_LEN:-_TRAILER_LEN]
 
@@ -284,11 +309,11 @@ class BmsBluetoothHandler:
     def parse_cell_info(frame: bytes) -> dict:
         """Parse a 0x04 cell voltage response frame.
 
-        Per spec: frame[3] (the header length byte) = cell_count × 2.
+        Per spec: frame[3] (the header length byte) = cell_count x 2.
         The payload contains ONLY the voltage bytes — no count byte.
-          0+    Cell voltages      uint16 BE each  unit mV  ÷1000 → V
+          0+    Cell voltages      uint16 BE each  unit mV  /1000 -> V
         """
-        count = frame[3] // 2          # header length byte = N_cells × 2
+        count = frame[3] // 2          # header length byte = N_cells x 2
         p = frame[_HEADER_LEN:-_TRAILER_LEN]
         voltages: list[float] = []
         for i in range(count):

custom_components/xiaoxiang_bms/const.py

@@ -5,8 +5,8 @@ DOMAIN = "xiaoxiang_bms"
 CONF_ADDRESS = "address"
 CONF_POLL_INTERVAL = "poll_interval"
 
-DEFAULT_POLL_INTERVAL = 15  # seconds — each poll does a full BLE connect/disconnect
+DEFAULT_POLL_INTERVAL = 30  # seconds — each poll does a full BLE connect/disconnect
-MIN_POLL_INTERVAL = 10      # below this the BMS has no breathing room between polls
+MIN_POLL_INTERVAL = 15      # below this the BMS has no breathing room between polls
 MAX_POLL_INTERVAL = 300
 
 # GATT UUIDs (Xiaoxiang BMS UART-over-GATT)

custom_components/xiaoxiang_bms/coordinator.py

@@ -5,6 +5,7 @@ import asyncio
 import logging
 from datetime import timedelta
 
+from bleak.backends.device import BLEDevice
 from homeassistant.components.bluetooth import async_ble_device_from_address
 from homeassistant.core import HomeAssistant
 from homeassistant.exceptions import HomeAssistantError
@@ -19,13 +20,13 @@ _LOGGER = logging.getLogger(__name__)
 # Only mark sensors unavailable after this many *consecutive* failed polls.
 # Transient BLE misses (device not in cache, ESPHome proxy busy, etc.) return
 # the last known data instead so the UI doesn't oscillate.
-_FAILURES_BEFORE_UNAVAILABLE = 3
+_FAILURES_BEFORE_UNAVAILABLE = 5
 
 
 class BmsCoordinator(DataUpdateCoordinator[dict]):
     """Polls the BMS over BLE and distributes data to all sensor entities.
 
-    Uses a connect → read → disconnect pattern on every poll so the BMS's
+    Uses a connect -> read -> disconnect pattern on every poll so the BMS's
     single BLE connection slot is free between updates (mobile app access).
     """
 
@@ -44,10 +45,12 @@ class BmsCoordinator(DataUpdateCoordinator[dict]):
         )
         self.address = address
         self._device_name = name
-        self._poll_timeout = max(poll_interval - 3, 10)
+        self._poll_timeout = max(poll_interval - 5, 20)
         self._handler = BmsBluetoothHandler(address)
         self.hw_version: str | None = None
         self._consecutive_failures = 0
+        # Kept fresh by the BLE advertisement callback registered in __init__.py
+        self._ble_device: BLEDevice | None = None
 
     # ------------------------------------------------------------------
     # Device info — shared by sensor, binary_sensor, number platforms
@@ -74,7 +77,7 @@ class BmsCoordinator(DataUpdateCoordinator[dict]):
 
     async def async_write_mos(self, value: int) -> None:
         """Send a MOS control command to the BMS, then refresh sensor state."""
-        device = async_ble_device_from_address(self.hass, self.address, connectable=True)
+        device = self._get_ble_device()
         if device is None:
             raise HomeAssistantError(
                 f"BMS ({self.address}) not reachable — cannot send MOS command"
@@ -82,9 +85,22 @@ class BmsCoordinator(DataUpdateCoordinator[dict]):
         success = await self._handler.write_mos(device, value)
         if not success:
             raise HomeAssistantError("BMS did not acknowledge the MOS command")
-        # Refresh immediately so sensors reflect the new MOS state
         await self.async_request_refresh()
 
+    # ------------------------------------------------------------------
+    # BLE device lookup
+    # ------------------------------------------------------------------
+
+    def _get_ble_device(self) -> BLEDevice | None:
+        """Return the freshest available BLEDevice reference.
+
+        Prefers the advertisement-callback reference (_ble_device) because it
+        tracks proxy transport path changes. Falls back to the scanner cache.
+        """
+        return self._ble_device or async_ble_device_from_address(
+            self.hass, self.address, connectable=True
+        )
+
     # ------------------------------------------------------------------
     # Poll
     # ------------------------------------------------------------------
@@ -92,7 +108,7 @@ class BmsCoordinator(DataUpdateCoordinator[dict]):
     def _handle_failure(self, reason: str) -> dict:
         """On a transient failure, return cached data up to the threshold.
 
-        Only raises UpdateFailed (→ sensors go unavailable) after
+        Only raises UpdateFailed (-> sensors go unavailable) after
         _FAILURES_BEFORE_UNAVAILABLE consecutive misses.
         """
         self._consecutive_failures += 1
@@ -109,14 +125,7 @@ class BmsCoordinator(DataUpdateCoordinator[dict]):
     async def _async_update_data(self) -> dict:
         """Connect to the BMS, fetch all data, disconnect."""
 
-        # The BMS may not be in the scanner cache immediately after a disconnect.
+        device = self._get_ble_device()
-        # Wait up to 2 s for an advertisement before giving up.
-        device = async_ble_device_from_address(self.hass, self.address, connectable=True)
-        if device is None:
-            await asyncio.sleep(2.0)
-            device = async_ble_device_from_address(
-                self.hass, self.address, connectable=True
-            )
         if device is None:
             return self._handle_failure(
                 f"BMS ({self.address}) not reachable — check Bluetooth adapter / proxy"