Lesson 9 · path 5
Fan-out: many questions, one call
Ask many questions in one call, even ones you might not need. Your code picks which answers matter. It's cheaper and faster than one call per question.
Fan-out: many questions in one call
Put many questions into one call. They all read the same state. Your code decides which answers matter (Fan-out).
You can even include speculative questions. Those are questions you might not need. If an answer turns out to be useless, your code just ignores it.
It's like a doctor's intake form. You answer ten questions on one sheet during one visit, not ten questions over ten separate appointments.
The state gets read once. The questions run in parallel. So one fan-out call beats a long line of single-question calls on cost and speed.
The parallel-questions cookbook tested this. Batching did not change the answers compared with one question per call. On their GDPR briefing example, it was about 12 times cheaper and about 10 times faster (Parallel questions).
Lab bridge: newsletter triage. It asks an urgency Noul, a topic Choice, and a keep Noul, all in one call.