Welcome to your interview.
The question is on your right: Plan an Offline Mobile Feature. Take a moment with it first.
Talk your thinking through with me if you like - when you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes). Discussion and graded submissions share your five interviewer interactions, so spend them well.
You're building a mobile feature that users may need to rely on even when their device has no connectivity for up to 30 minutes. You want the experience to remain useful during that window, while avoiding data loss, duplicate actions, or confusing state once the device reconnects.
How would you handle a feature that needs to work when the device is offline for 30 minutes at a time?