Backend

Outcome: Complete the task with Backend (Backend). User context: No checkout, o backend checa o estoque, cobra o pagamento e salva o resultado do pedido. Technical concept or control: Backend (Backend). Why it fits: Coloque regras confiáveis, dados compartilhados, integrações e trabalhos que necessitam de servidor no backend. Do not use it when: Nunca confie apenas em verificações no lado do cliente para segurança ou dinheiro. 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): Nenhum padrão oficial único controla todo o termo. Seu significado pode mudar entre equipes, plataformas ou frameworks. 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.