During August 2025, Leo worked on the starkware-libs/stwo repository, focusing on cryptographic hashing reliability within Poseidon-based channel operations. He addressed a subtle bug in the Poseidon252Channel by implementing a length padding fix, ensuring the last element of the hash input includes the original data length. This adjustment reinforced data integrity and correctness for the Poseidon mix_u32s function, reducing the risk of incorrect hashes in channel computations. Leo’s work required expertise in Rust, low-level programming, and hashing algorithms, demonstrating careful attention to cryptographic detail and contributing to the overall security and trustworthiness of the library’s primitives.