During December 2024, this developer delivered the ANTS Pre-application Number Validation feature for the betagouv/rdv-service-public repository. They designed and implemented a centralized validator that integrates with the ANTS API to verify pre-application status and check for existing appointments, streamlining applicant screening and reducing manual follow-ups. The work involved refactoring the validation logic to unify ANTS number checks, which improved reliability and maintainability across the backend. Utilizing Ruby and HTML, they focused on backend development, API integration, and form validation. Minor edge-case fixes were addressed as part of the refactor, strengthening compliance with ANTS data requirements throughout the system.