During October 2024, Cheng Ji focused on backend development and refactoring within the xupefei/delta repository, delivering a targeted improvement to the checkpointing workflow. He refactored the internal checkpoint function to accept a CatalogTable object instead of a TableIdentifier, enabling the process to leverage richer table metadata. This change, implemented in Scala, enhanced the robustness and future extensibility of checkpointing without introducing user-facing modifications. By exposing more comprehensive metadata, Cheng’s work laid the groundwork for easier evolution of catalog-based features. The depth of the refactor demonstrates a thoughtful approach to maintainability and adaptability in backend API design and implementation.