Liwei Dai focused on backend development for the FlagTree/flagtree repository, addressing a core issue related to CPU support in the getPointer function. By reverting a previous workaround, Liwei restored the original functionality, ensuring the code aligned with its intended design and simplifying the code path. This change removed unnecessary complexity, improving maintainability and stability across CPU architectures while preserving performance. The work required a strong understanding of Python and CUDA, as well as careful attention to cross-platform compatibility. Although the period involved fixing a single bug, the solution demonstrated depth in codebase analysis and thoughtful engineering decision-making.