Chengusky developed an OAuth2 API client for LLM services in the knownsec/aipyapp repository, focusing on secure token retrieval and efficient authorization header management. Using Python and the httpx library, Chengusky refactored the client to enable token reuse, reducing authentication overhead and improving compatibility with various clients. The migration to httpx enhanced performance and concurrency, resulting in lower API call latency. By clearly separating concerns and documenting the API surface, Chengusky improved both security and maintainability. The work addressed an incompatible client issue and delivered measurable business value through faster, more secure API calls and streamlined maintenance for client-server architectures.