During February 2026, Fabrice contributed to the bitcoin/bitcoin repository by addressing a critical bug affecting mempool-spender index synchronization. He implemented an optimization in C++ and Python that ensures the transaction output spender index synchronizes only after confirming through a mempool check that no relevant spending transactions exist, and only when necessary. This approach minimizes locking on the mempool, reducing the risk of outdated spending transactions being included in blocks and improving block validity under dynamic network conditions. Fabrice’s work demonstrated depth in blockchain development and functional testing, resulting in a targeted performance improvement that enhanced protocol reliability and user trust.