During September 2025, this developer focused on enhancing build reliability for the OpenXiangShan/difftest repository by addressing a module-ambiguity issue in the VCS simulation environment. They resolved a persistent bug by updating the build system’s Makefile, explicitly specifying the top-level module through the addition of the -top $(VCS_TOP) flag to VCS_FLAGS. This change ensured that the correct module was always selected during simulation and compilation, reducing the risk of build failures and improving CI stability. Their work demonstrated practical expertise in build systems and version control, with a technical emphasis on Makefile scripting and continuous integration workflows.