Design user interview questions

You have five research calls booked and one chance to not lead the witness.

Write a user interview guide for the topic below, for a 30 minute call.

Rules:
1. Ask about past behaviour, not future intention. Replace every "would you" with a question about what they actually did.
2. No question may mention our idea or product until the final section.
3. Start broad, narrow later. Open with the last time they encountered the problem.
4. Include follow-up probes: what happened next, what did you do instead, how often, who else was involved.
5. Mark any question that is leading, and rewrite it.

Output: warm-up, main sequence with probes, a short section for reactions if they raise our area themselves, and a close. Then list the three things I am hoping to hear, and warn me how I might unconsciously steer the conversation towards them.

Topic and what I want to learn:

Discovery and evidence. Checking the idea before you commit: research, feedback, competitors, risky assumptions, success metrics.