Backend

Outcome: Complete the task with Backend (Backend). User context: Al pagar, el servidor revisa el inventario, cobra el pago y guarda el resultado del pedido. Technical concept or control: Backend (Backend). Why it fits: Coloca reglas confiables, datos compartidos, integraciones y trabajo que necesite un servidor en el backend. Do not use it when: Nunca confíes solo en las comprobaciones del lado del cliente para la seguridad o el dinero. Engineering requirements: Define inputs, outputs, contracts, and rules that must always hold. Set authorization and input checks. Define failures, timeouts, retries, one-time effects, data moves, and compatibility limits. Operations: Add useful signals and logs that hide sensitive data. Set capacity limits and write an operator guide. Test recovery and rollback. Acceptance criteria: Contract and failure-path tests pass. Data and authorization rules still hold during retries and partial failures. Check performance limits, monitoring, recovery, and rollback. Evidence and limits (evidence boundary): Ningún estándar oficial único controla todo el término. Su significado puede cambiar según equipos, plataformas o marcos. Unknowns to confirm: Where the code runs, data stores, traffic shape, consistency needs, and the security boundary. Also confirm the compatibility period, service goals, and rollback limits.