How does a request flow through FastAPI and its ASGI stack?

I avoid memorizing one oversimplified sequence because streaming responses, yield dependency scopes, exception handling, and background tasks change resource timing. Instead, I identify which component owns a resource and when the response becomes committed. Middleware must still produce required headers on failures, request-scoped objects must not escape into later work, and a stream must own anything it uses until iteration ends. Traces should separate queueing, validation, dependency, handler, serialization, and downstream time so lifecycle knowledge becomes operational evidence.