The payoff

Done well, streaming transforms the perceived quality of an agent. A turn that takes fifteen seconds feels fast because the user sees reasoning, then "reading contract.pdf," then the answer flowing in, then a download card: a narrative of work, not a frozen screen. The architecture that delivers this, an event-emitting orchestrator, an SSE transport, a typed event timeline, and a persisted-events data model, is the same architecture that makes your agent debuggable and your history faithful. Streaming isn't a feature you add; it's a shape you build in.