Wencheng Yao developed a new User Defined Function (UDF) called split_part for the OpenSPG/openspg repository, enabling flexible string splitting and retrieval of specific segments, including support for negative indices to access elements from the end of a string. He approached the task with a strong emphasis on test-driven development, creating comprehensive unit tests to cover a wide range of inputs and edge cases, ensuring both correctness and regression safety. Working primarily in Java and focusing on backend and UDF development, Wencheng enhanced the Reasoner module’s data extraction capabilities, allowing for more robust and adaptable query expressions within the project.