Worked on transaction validation optimization in the aptos-labs/aptos-core repository, focusing on improving the reliability and performance of the cold validation path. Refactored the pending requirements structure from a list to a single optional entry, ensuring only one pending requirement could exist and aligning with the commit-only recording flow. Introduced an optimization to skip unnecessary indices when advancing the minimum unprocessed index, which increased throughput. Added invariant checks to enforce correctness and prevent regressions, and enhanced documentation to clarify the new logic. Utilized Rust and backend development skills to deliver maintainable, well-documented code that reduces commit-block risk.