Colm Donelan focused on improving build stability for the google/XNNPACK repository by addressing a critical SME2 compatibility issue in September 2025. He resolved a blocking build failure in the GEMMBenchmark component by updating the constructor signature from size_t to ConstantOrFunction in both the implementation and header files. This change maintained API compatibility, ensuring that SME2-enabled builds remained stable without requiring modifications from downstream consumers. Colm applied his expertise in C++ and build systems to reinforce release reliability for ARM configurations, demonstrating a thoughtful approach to type-system improvements and risk mitigation during the early stages of the release cycle.