Add global BLE lock + faster timeouts for multi-device reliability

Root cause: 3 BMS devices fighting for 3 ESPHome proxy connection slots
simultaneously, causing 80% timeout failures and 22s+ poll times.

Fixes:
- Add shared asyncio.Lock so only one BMS polls at a time — eliminates
  proxy slot contention entirely
- Pass ble_device_callback to establish_connection so retry attempts
  get a fresh BLEDevice (handles proxy path changes)
- Reduce command timeout 5s -> 3s, retries 3 -> 2 (BMS responds in
  <200ms when connection is clean)
- Reduce establish_connection max_attempts 3 -> 2 (fail fast, retry
  next cycle instead of blocking 25s)
- Fixed poll timeout to 15s (was poll_interval-5=25s)

Expected: polls complete in 2-5s instead of 22s, ~95%+ success rate.

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

custom_components/xiaoxiang_bms/bluetooth_handler.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 import asyncio
 import logging
 import struct
+from collections.abc import Callable
 
 from bleak import BleakError
 from bleak.backends.device import BLEDevice
@@ -63,8 +64,9 @@ class BmsBluetoothHandler:
         self,
         ble_device: BLEDevice,
         commands: list[bytes],
-        timeout: float = 5.0,
-        retries: int = 3,
+        timeout: float = 3.0,
+        retries: int = 2,
+        ble_device_callback: Callable[[], BLEDevice | None] | None = None,
     ) -> list[bytes | None]:
         """Connect, send each command in sequence, disconnect.
 
@@ -79,7 +81,8 @@ class BmsBluetoothHandler:
             BleakClientWithServiceCache,
             ble_device,
             self._address,
-            max_attempts=3,
+            max_attempts=2,
+            ble_device_callback=ble_device_callback,
         )
         try:
             await client.start_notify(RX_CHAR_UUID, self._on_notify)
@@ -166,7 +169,7 @@ class BmsBluetoothHandler:
                     _LOGGER.warning("BLE write failed (attempt %d/%d): %s",
                                     attempt, retries, exc)
                     if attempt < retries:
-                        await asyncio.sleep(0.5)
+                        await asyncio.sleep(0.3)
                     continue
 
             try:
@@ -178,7 +181,7 @@ class BmsBluetoothHandler:
                 _LOGGER.warning("BMS timeout (cmd=0x%s, attempt %d/%d)",
                                 command.hex(), attempt, retries)
                 if attempt < retries:
-                    await asyncio.sleep(0.5)
+                    await asyncio.sleep(0.3)
 
         return None
 
@@ -186,7 +189,12 @@ class BmsBluetoothHandler:
     # MOS write command
     # ------------------------------------------------------------------
 
-    async def write_mos(self, ble_device: BLEDevice, value: int) -> bool:
+    async def write_mos(
+        self,
+        ble_device: BLEDevice,
+        value: int,
+        ble_device_callback: Callable[[], BLEDevice | None] | None = None,
+    ) -> bool:
         """Send a MOS control write command and return True on ACK.
 
         Follows the same connect -> send -> disconnect pattern as poll() so
@@ -200,12 +208,13 @@ class BmsBluetoothHandler:
             BleakClientWithServiceCache,
             ble_device,
             self._address,
-            max_attempts=3,
+            max_attempts=2,
+            ble_device_callback=ble_device_callback,
         )
         try:
             await client.start_notify(RX_CHAR_UUID, self._on_notify)
             await asyncio.sleep(0.3)
-            response = await self._request(client, command, timeout=5.0, retries=2)
+            response = await self._request(client, command, timeout=3.0, retries=2)
             return response is not None and response[2] == 0x00
         finally:
             try: