During September 2025, Nathan Springer focused on stabilizing distributed Link Time Optimization (LTO) for macOS within the facebook/buck2-prelude repository. He addressed a critical build issue by reverting a previous change that had removed unused linker flags during the optimizer step, which had inadvertently caused LTO failures on Darwin systems. Using his expertise in build systems, compiler toolchains, and linker behavior, Nathan carefully restored the prior flag handling to ensure reliable cross-platform builds. Working primarily in Python, he validated the solution by maintaining build stability and minimizing risk, demonstrating a thoughtful approach to change management and repository-wide build integrity.