Adrien developed the ANTS Pre-application Number Validation feature for the betagouv/rdv-service-public repository, focusing on backend development and API integration using Ruby and HTML. He designed and implemented a centralized validator that connects with the ANTS API to verify pre-application statuses and check for existing appointments, streamlining applicant screening and reducing manual follow-ups. As part of this work, Adrien refactored the validation logic to unify and standardize ANTS number checks across the system, improving code maintainability and reliability. The project addressed edge-case validation issues and strengthened compliance with ANTS data requirements, demonstrating thoughtful form validation and refactoring practices.