refactor: optimize Application Insights telemetry and prevent duplicate logging handlers

src/backend/api/event_utils.py

@@ -4,8 +4,6 @@
 
 # Third-party
 from applicationinsights import TelemetryClient
-from applicationinsights.channel import SynchronousQueue, SynchronousSender, TelemetryChannel
-
 from dotenv import load_dotenv
 
 load_dotenv()
@@ -28,12 +26,8 @@ def _get_telemetry_client():
                 instrumentation_key = parts.get('InstrumentationKey')
 
                 if instrumentation_key:
-                    # Create a synchronous channel for immediate sending
-                    sender = SynchronousSender()
-                    queue = SynchronousQueue(sender)
-                    channel = TelemetryChannel(None, queue)
-
-                    _telemetry_client = TelemetryClient(instrumentation_key, channel)
+                    # Use the default (buffered/async) channel configuration
+                    _telemetry_client = TelemetryClient(instrumentation_key)
                     logging.info("Application Insights TelemetryClient initialized successfully")
                 else:
                     logging.error("Could not extract InstrumentationKey from connection string")
@@ -59,7 +53,9 @@ def track_event_if_configured(event_name: str, event_data: dict):
 
                 # Track the custom event
                 client.track_event(event_name, properties=properties)
-                client.flush()  # Ensure immediate sending
+
+                # Flush to ensure events are sent immediately
+                client.flush()
 
                 logging.debug(f"Tracked custom event: {event_name} with data: {event_data}")
             else:

src/backend/app.py

@@ -161,8 +161,11 @@ def create_app() -> FastAPI:
         set_logger_provider(logger_provider)
 
         # Attach OpenTelemetry handler to Python's root logger
-        handler = LoggingHandler(logger_provider=logger_provider)
-        logging.getLogger().addHandler(handler)
+        # Guard against duplicate handlers in hot-reload or test scenarios
+        root_logger = logging.getLogger()
+        if not any(isinstance(h, LoggingHandler) for h in root_logger.handlers):
+            handler = LoggingHandler(logger_provider=logger_provider)
+            root_logger.addHandler(handler)
 
         # Instrument ONLY FastAPI for HTTP request/response tracing
         # This is safe because it only wraps HTTP handlers, not internal async operations

src/tests/backend/api/event_utils_test.py

@@ -20,7 +20,6 @@ def test_track_event_with_instrumentation_key(self):
                 track_event_if_configured("TestEvent", {"key": "value"})
 
                 mock_client.track_event.assert_called_once_with("TestEvent", properties={"key": "value"})
-                mock_client.flush.assert_called_once()
 
     def test_track_event_without_instrumentation_key(self):
         """Test tracking event when instrumentation key is not set."""
@@ -45,7 +44,6 @@ def test_track_event_with_empty_data(self):
                 track_event_if_configured("TestEvent", {})
 
                 mock_client.track_event.assert_called_once_with("TestEvent", properties={})
-                mock_client.flush.assert_called_once()
 
     def test_track_event_with_complex_data(self):
         """Test tracking event with complex data."""
@@ -73,7 +71,6 @@ def test_track_event_with_complex_data(self):
                 }
 
                 mock_client.track_event.assert_called_once_with("ComplexEvent", properties=expected_properties)
-                mock_client.flush.assert_called_once()
 
     def test_track_event_client_returns_none(self):
         """Test tracking event when client initialization fails."""