C4 component diagram for CU-21 Verificar Estado del Peritaje—a layered inspection status verification system with React frontend, FastAPI REST controller, business logic service, and SQLAlchemy data access layer. User requests flow from the SPA through the PeritajeController to PeritajeService for validation and business rules, then to PeritajeDAO for database queries against PostgreSQL. This architecture demonstrates separation of concerns and testability, enabling secure, role-based access to inspection history and status details for buyers and sellers. Fork and customize this diagram on Diagrams.so to adapt the pattern for your own multi-tier applications.