Design Credit Card Application System

Design a cloud-native credit-card application platform that can process 10 000+ applications per hour with sub-second p99 latency for the synchronous “apply” API while orchestrating a multi-step back-office workflow that includes identity (KYC) verification, credit-bureau pulls, real-time fraud screening, ML-based risk scoring, and an auditable approve/decline/manual-review decision. The system must be resilient to downstream failures, horizontally scalable across regions, and satisfy U.S. financial-regulatory requirements (adverse-action notices, fair-lending auditability, 7-year immutable data retention, PII encryption). Provide high-level architecture, data models, API contracts, workflow orchestration strategy, external-service integration patterns (circuit breaker, retries, idempotency), risk-engine design, and compliance/observability hooks. You have 45 minutes: start with requirements clarification, then walk through your design, justify technology choices, and discuss scale, failure modes, and cost.