During December 2025, Hyln9 focused on stabilizing the build system for the pytorch/pytorch repository, addressing performance issues in CUDA workflows. They resolved a ccache-related caching problem in torch.utils.cpp_extension by replacing long-form nvcc dependency flags with their short-form equivalents, such as -MD and -MF. This technical approach, implemented in C++ and CUDA, improved build reliability and reduced cache misses during incremental builds. Hyln9 validated the solution across both CI and local environments, ensuring consistent results. Although the work centered on a single bug fix, it demonstrated a deep understanding of build systems and their interaction with CUDA toolchains.