Hilbrand contributed to the kiesraad/abacus repository by focusing on code quality and reliability in the Rust-based Seat Assignment Module. Over two months, Hilbrand enhanced test data integrity, correcting a documentation error in the test suite to ensure that seat allocation logic was accurately reflected and reducing the risk of future regressions. In addition, Hilbrand improved code maintainability by updating in-code comments, clarifying the use of 'highest averages' terminology in the seat assignment process. Through targeted code refactoring, documentation updates, and rigorous testing, Hilbrand’s work supported clearer onboarding and more robust validation of the module’s core allocation functionality.