Heiko Theissen contributed targeted engineering work to the cap-js/openapi and capire/docs repositories over a two-month period, focusing on reliability and clarity in OData and OpenAPI integrations. He addressed a nuanced bug in cap-js/openapi by implementing logic in JavaScript to resolve parameter alias conflicts with system query options, enhancing OpenAPI conversion correctness and reducing downstream errors. In capire/docs, Heiko improved OData Aggregation documentation by enforcing the mandatory use of the Aggregation.default annotation and providing a practical SUM example, using Markdown to clarify configuration requirements. His work demonstrated depth in API development, OData, and technical documentation.