During May 2025, Haoyan Luo focused on enhancing the reliability of the VectifyAI/PageIndex repository by addressing a critical issue in table of contents (TOC) handling. He developed a robust backend solution in Python that validates and safely truncates TOC indices, ensuring references do not exceed document length or point to non-existent pages. By introducing a dedicated function for physical index validation and error handling, Haoyan improved the stability of navigation and indexing workflows in document-heavy pipelines. This targeted bug fix reduced user-facing errors and support needs, demonstrating depth in backend development, data validation, and defensive programming within production systems.