During October 2024, Cheng Ji refactored the checkpointing workflow in the xupefei/delta repository to enhance backend robustness and future extensibility. He redesigned the internal checkpoint function to accept a CatalogTable object instead of a TableIdentifier, enabling the process to leverage richer metadata and better support catalog-based features. This backend development and refactoring effort, implemented in Scala, improved the API surface and metadata exposure without introducing user-facing changes. The work demonstrated a thoughtful approach to evolving internal APIs for maintainability and scalability, focusing on long-term stability and easier feature evolution within the checkpointing infrastructure. No bugs were reported or fixed.