Bob Bobbio expanded the BigInt capabilities in the risc0/zirgen repository by introducing a new mul_256 bigint2 precompile and migrating the modmul_256 operation with updated build support. Working primarily in C++ and Rust, Bob designed and integrated new files and build configurations to enable efficient 256-bit arithmetic within the bigint circuit, directly supporting advanced cryptographic computations. The work focused on circuit design and build systems, laying a technical foundation for future optimizations. Over the course of the month, Bob’s contributions addressed the need for robust big-integer operations, demonstrating depth in both low-level implementation and system integration.