Worked on the mbta/api repository to enhance API contract fidelity by updating documentation to accurately reflect the data model. Focused on a targeted fix that marked Facility latitude and longitude fields as nullable in the Swagger specification, reducing integration risk for downstream clients. This change, implemented in Elixir and leveraging API development and documentation skills, ensured that API consumers could rely on precise contract details. The update was carefully tracked through issue and commit references, demonstrating a methodical approach to traceability and collaboration. The work improved developer experience by aligning documentation with actual API behavior, supporting more reliable client integrations.