CSV report generator
Design a CSV report generator for a SaaS dashboard. A user clicks 'export', and the system produces a CSV of their data (could be a few rows or up to a few hundred thousand) and lets them download it. Small reports should feel instant; large ones can take a while. Describe how you generate the file and deliver it to the user without timing out the web request.
What a strong answer looks like
Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts (data model, bottlenecks, consistency, failure modes) and name the trade-offs you are making.
Clarify3:30 left
Estimate3:30 planned
Design10:00 planned
Deep dive8:00 planned
Failure5:00 planned
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.