Worked on the alibaba/loongsuite-python-agent repository to enhance the reliability and observability of FastAPI applications by refactoring the middleware stack for improved error handling and tracing. Focused on hardening the FastAPI instrumentor middleware, the work ensured that exceptions are gracefully managed and accurately recorded within OpenTelemetry tracing spans. Developed comprehensive end-to-end tests to validate failsafe behavior and correct HTTP status code reporting, while also updating documentation and the project changelog. Utilized Python and backend development skills to streamline exception handling paths, reduce false positives, and enable more effective incident diagnosis in production environments through robust tracing improvements.