During August 2025, Schwertfeger enhanced authentication workflows in the modelix.core repository by implementing a seamless OAuth token refresh mechanism within the mps-sync-plugin. Using Kotlin and focusing on backend development and token management, he automated the refresh process so that expired access tokens are replaced without requiring user re-authorization, thereby reducing session interruptions. He also improved observability by adding detailed logging and debugging for OAuth port discovery, which aids in diagnosing authentication issues and reduces mean time to resolution. These changes maintained the existing security posture and authentication logic, reflecting a focused, maintainable approach to backend authentication engineering.