Yifan Feng worked on stabilizing the build environment for the ucb-bar/chipyard repository by focusing on build configuration and dependency management using YAML. During this period, Yifan addressed reproducibility issues in the continuous integration process by pinning the which tool dependency to version 2.21. This technical approach reduced build fragility and minimized failures caused by dependency drift, resulting in more predictable and repeatable builds. By locking a critical build tool to a known-good version, Yifan enabled smoother onboarding for contributors and supported more reliable development cycles. The work demonstrated a targeted, foundational improvement rather than broad or complex feature development.