Lucas Silveira Ribeiro developed foundational backend modules for the marcosdosea/gcm-ufs repository over a two-month period, focusing on payments, sales, and client management systems. He established modular workflows by creating Java classes such as GerenciadorPagamentos and GerenciadorVendas, enabling transaction processing and sales operations. Lucas migrated client data management from a legacy system to a new CRUD-based approach, improving maintainability and scalability. His work emphasized object-oriented programming principles and careful class-level refactoring to support future extensibility. While the scope was limited to three features without bug fixes, the contributions provided a robust base for ongoing backend development in Java.