Your question is Real-Time Fraud Detection. 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).
Design a real-time fraud detection system for credit card transactions at Capital One.
Describe a production-ready streaming pipeline from transaction ingestion through validation, enrichment, fraud scoring, and decisioning. Address schema evolution, ordering, deduplication, idempotency, late events, replay and backfill, fault tolerance, data quality, observability, security, and how batch processing complements the real-time path. Explain the trade-offs behind your technology choices and how the design would support exactly-once or effectively-once outcomes.