Your question is Backfill Missing Customer Data. 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 are supporting a customer data pipeline after an upstream defect caused a gap in downstream records. The source issue has been fixed, and the missing data now needs to be replayed without duplicating existing rows or breaking downstream reports. You need to decide how to reprocess the affected time range, validate completeness, and keep the pipeline stable while the backfill runs.
How would you backfill missing customer data after an upstream issue is fixed?