During November 2024, Der focused on API specification engineering for the mcgallan/azure-rest-api-specs repository, specifically targeting the Face Recognition API. He delivered a schema update that reordered the faceId and persistedFaceId fields, ensuring the primary identifier appears first to clarify data semantics and support updated integration requirements. Working with YAML and leveraging OpenAPI Specification, Der updated both the API schema and its documentation, verifying the impact on data flow and downstream processes. His disciplined approach to version control, including traceable commits and issue referencing, demonstrated attention to maintainability and future enhancements, though the scope was limited to a single feature change.