fix mypy errors with improved MQTT reliability implementation

- Add _reason_info helper method to extract reason names safely
- Update connect/disconnect callbacks to use string comparison instead of numeric
- Fix type annotations with proper Optional[Client] typing
- Resolve unreachable code warnings with type ignore comments for threading
- Improve error handling with robust try/finally blocks in stop method
- Maintain fresh client creation approach for reliable reconnection

🤖 Generated with [Claude Code](https://claude.ai/code)

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

frigate/comms/mqtt.py

@@ -1,7 +1,7 @@
 import logging
 import threading
 import time
-from typing import Any, Callable
+from typing import Any, Callable, Optional
 
 import paho.mqtt.client as mqtt
 from paho.mqtt.enums import CallbackAPIVersion
@@ -19,18 +19,20 @@ class MqttClient(Communicator):
         self.config = config
         self.mqtt_config = config.mqtt
         self.connected = False
-        self._reconnect_thread = None
+        self.client: Optional[mqtt.Client] = None
+        self._dispatcher: Callable[[str, str], None] = lambda *_: None
+        self._reconnect_thread: Optional[threading.Thread] = None
         self._reconnect_delay = 10  # Retry every 10 seconds
-        self._stop_reconnect = False
+        self._stop_reconnect: bool = False
 
-    def subscribe(self, receiver: Callable) -> None:
+    def subscribe(self, receiver: Callable[[str, str], None]) -> None:
         """Wrapper for allowing dispatcher to subscribe."""
         self._dispatcher = receiver
         self._start()
 
     def publish(self, topic: str, payload: Any, retain: bool = False) -> None:
         """Wrapper for publishing when client is in valid state."""
-        if not self.connected:
+        if not self.connected or self.client is None:
             logger.debug(f"Unable to publish to {topic}: client is not connected")
             return
 
@@ -43,10 +45,16 @@ class MqttClient(Communicator):
 
     def stop(self) -> None:
         self._stop_reconnect = True
-        if self._reconnect_thread and self._reconnect_thread.is_alive():
+        if self._reconnect_thread is not None and self._reconnect_thread.is_alive():
             self._reconnect_thread.join(timeout=5)
-        if hasattr(self, "client"):
+        if self.client is not None:
+            try:
                 self.client.disconnect()
+            finally:
+                try:
+                    self.client.loop_stop()
+                except Exception:
+                    pass
 
     def _set_initial_topics(self) -> None:
         """Set initial state topics."""
@@ -150,6 +158,20 @@ class MqttClient(Communicator):
 
         self.publish("available", "online", retain=True)
 
+    @staticmethod
+    def _reason_info(reason_code: object) -> str:
+        """Return human_readable_name for a Paho reason code."""
+        # Name string
+        if hasattr(reason_code, "getName") and callable(getattr(reason_code, "getName")):
+            try:
+                name = str(getattr(reason_code, "getName")())
+            except Exception:
+                name = str(reason_code)
+        else:
+            name = str(reason_code)
+
+        return name
+
     def on_mqtt_command(
         self, client: mqtt.Client, userdata: Any, message: mqtt.MQTTMessage
     ) -> None:
@@ -163,27 +185,23 @@ class MqttClient(Communicator):
         client: mqtt.Client,
         userdata: Any,
         flags: Any,
-        reason_code: mqtt.ReasonCode,  # type: ignore[name-defined]
+        reason_code: object,
         properties: Any,
     ) -> None:
         """Mqtt connection callback."""
         threading.current_thread().name = "mqtt"
-        if reason_code != 0:
+        reason_name = self._reason_info(reason_code)
-            if reason_code == "Server unavailable":
+
-                logger.error(
+        # Check for connection failure by comparing reason name
-                    "Unable to connect to MQTT server: MQTT Server unavailable"
+        if reason_name != "Success":
-                )
+            if reason_name == "Server unavailable":
-            elif reason_code == "Bad user name or password":
+                logger.error("Unable to connect to MQTT server: MQTT Server unavailable")
-                logger.error(
+            elif reason_name == "Bad user name or password":
-                    "Unable to connect to MQTT server: MQTT Bad username or password"
+                logger.error("Unable to connect to MQTT server: MQTT Bad username or password")
-                )
+            elif reason_name == "Not authorized":
-            elif reason_code == "Not authorized":
                 logger.error("Unable to connect to MQTT server: MQTT Not authorized")
             else:
-                logger.error(
+                logger.error(f"Unable to connect to MQTT server: Connection refused. Error: {reason_name}")
-                    "Unable to connect to MQTT server: Connection refused. Error code: "
-                    + reason_code.getName()
-                )
             # Don't set connected = True on connection failure
             return
 
@@ -225,7 +243,7 @@ class MqttClient(Communicator):
         logger.error("MQTT will attempt reconnection...")
 
         # Start reconnection in a separate thread to avoid blocking
-        if not self._reconnect_thread or not self._reconnect_thread.is_alive():
+        if self._reconnect_thread is None or not self._reconnect_thread.is_alive():
             self._reconnect_thread = threading.Thread(
                 target=self._reconnect_loop, name="mqtt-reconnect", daemon=True
             )
@@ -323,6 +341,7 @@ class MqttClient(Communicator):
         """Handle MQTT reconnection using fresh client creation, retrying every 10 seconds indefinitely."""
         logger.error("MQTT reconnection loop started")
         attempt = 0
+        
         while not self._stop_reconnect and not self.connected:
             attempt += 1
 
@@ -331,15 +350,18 @@ class MqttClient(Communicator):
             )
 
             # Wait with ability to exit early if stopping
-            for _ in range(self._reconnect_delay):
+            delay_count = 0
+            while delay_count < self._reconnect_delay:
                 if self._stop_reconnect:
-                    logger.error("MQTT reconnection stopped during delay")
+                    logger.error("MQTT reconnection stopped during delay")  # type: ignore[unreachable]
                     return
                 time.sleep(1)
+                delay_count += 1
 
+            # Double-check stop flag after delay
             if self._stop_reconnect:
-                logger.error("MQTT reconnection stopped after delay")
+                logger.error("MQTT reconnection stopped after delay")  # type: ignore[unreachable]
-                break
+                return
 
             try:
                 logger.error(
@@ -347,7 +369,7 @@ class MqttClient(Communicator):
                 )
 
                 # Clean up old client if it exists
-                if hasattr(self, "client"):
+                if self.client is not None:
                     try:
                         self.client.disconnect()
                         self.client.loop_stop()
@@ -358,20 +380,22 @@ class MqttClient(Communicator):
                 self._start()
 
                 # Give the connection attempt some time to complete
-                for _ in range(5):  # Wait up to 5 seconds for connection
+                wait_count = 0
+                while wait_count < 5:  # Wait up to 5 seconds for connection
                     if self.connected:
-                        logger.error(
+                        logger.error(  # type: ignore[unreachable]
                             f"MQTT fresh connection successful on attempt {attempt}!"
                         )
                         return
                     time.sleep(1)
+                    wait_count += 1
 
                 logger.error(
                     f"MQTT fresh connection attempt {attempt} timed out, will retry"
                 )
-                # Continue the loop to retry
+                # Continue the outer while loop to retry
             except Exception as e:
                 logger.error(f"MQTT fresh connection attempt {attempt} failed: {e}")
-                # Continue the loop to retry
+                # Continue the outer while loop to retry
 
         logger.error("MQTT reconnection loop finished")