Your question is Power Analysis for Rare Metrics. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
You're evaluating an experiment where the outcome you care about happens very infrequently, such as a rare conversion or failure event in a product flow. The team wants to know how to reason about detectability when the primary metric is sparse.
How would you think about statistical power when the metric you care about is rare?