Added Ruff linting

src/main.py

@@ -106,10 +106,10 @@ async def pull_notifications(
 		)
 	except (AMQPException, OSError) as e:
 		logger.error(f"[FastAPI] RabbitMQ unavailable for user_id={user_id}: {e}")
-		raise HTTPException(status_code=503, detail="Message broker unavailable")
+		raise HTTPException(status_code=503, detail="Message broker unavailable") from e
 	except RuntimeError as e:
 		logger.error(f"[FastAPI] Consumer not ready: {e}")
-		raise HTTPException(status_code=503, detail="Service not ready")
+		raise HTTPException(status_code=503, detail="Service not ready") from e
 
 	logger.info(f"[FastAPI] Retrieved {len(messages)} message(s) for user_id={user_id}")
 	return PullResponse(messages=messages, count=len(messages), has_more=len(messages) >= MAX_MESSAGES)

src/metrics_server.py

@@ -1,5 +1,5 @@
 from fastapi import FastAPI, Response
-from prometheus_client import generate_latest, CONTENT_TYPE_LATEST, Counter
+from prometheus_client import CONTENT_TYPE_LATEST, Counter, generate_latest
 
 metrics_api = FastAPI(title="Metrics Server", description="Prometheus metrics endpoint")
 

src/rabbitmq_handler.py

@@ -78,11 +78,11 @@ class RabbitMQConsumer:
 
 		- Only one fetch per user runs at a time; different users run concurrently.
 		- Messages are acked after the whole batch has been read, so an error mid-read
-		  puts the batch back on the queue and re-raises.
+		puts the batch back on the queue and re-raises.
 		- Undecodable messages are rejected without requeue (discarded).
 		- Returns an empty list if nothing is queued.
 		- Delivery is at-most-once towards the client: messages are acked before the
-		  HTTP response is sent.
+		HTTP response is sent.
 		"""
 
 		if self._closing: