Code Room
System designHard
Question
Design a monitoring system for a loan-default prediction model where the true label — did the borrower actually default — only resolves months to years after the prediction. You can't wait that long to know the model is degrading. Walk through how you monitor model health when ground truth is delayed by quarters, what early proxy signals you use, and how you avoid both crying wolf and missing a real regression in the meantime.
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.
Learn the concepts
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Run or narrate your approach, then ask the coach.