Nicolas Oudard worked on data quality exploration for the incubateur-ademe/quefairedemesobjets repository, focusing on improving data type normalization during data downloads. Using Python and leveraging data engineering and ETL skills, he implemented a feature to cast all columns to strings, aiming to simplify downstream processing and ensure consistency. He also developed a refinement to format postal codes by padding leading zeros for codes below 10000, enhancing lookup accuracy. After evaluating the impact on existing data contracts, Nicolas reverted the changes and documented key learnings, outlining a plan for safer, incremental rollout with comprehensive testing in CI and staging environments.