Your question is Design a Transaction Risk Scoring System. 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 building an ML system for a financial platform that must score incoming transactions in real time and help decide whether to approve, review, or block them. The system must learn from historical activity and adapt as fraud patterns and user behavior change.
How would you approach designing a system to handle millions of transactions per second?