Worked on backend stability for Buck 2, focusing on resolving multiprocessing spawn issues that affected parallel build reliability. Addressed environment setup problems in standalone fastzip PARs by coordinating and implementing targeted reverts across both the facebook/buck2 and facebook/buck2-prelude repositories. Used Python to restore stable multiprocessing behavior, reducing failures related to spawn preparation data changes. The approach emphasized cross-repository consistency and code health, ensuring that parallel builds remained robust while ongoing performance work continued. No new features were introduced during this period, but two critical bugs were fixed, demonstrating a methodical approach to backend development and system reliability.