Developed a new Block Kramdown Retrieval API for the siyuan-note/siyuan repository, focusing on enhancing multi-block data access and export flexibility. The work involved designing an endpoint that retrieves multiple block kramdowns based on provided IDs and export modes, with robust input validation to ensure data integrity and security. Integrated the feature with the internal kernel API, enabling seamless data retrieval workflows within the backend system. Utilized Go for backend and API development, emphasizing maintainable code and clear validation logic. The implementation addressed the need for flexible export options, supporting various data workflows without introducing new bugs during the development period.