Design a Credit Approval Risk Engine

Design a system that evaluates credit card applications and decides whether to approve, deny, or send them to manual review. The system calls many external providers (credit bureau, KYC/AML, fraud, income/employment verification), so downstream integrations are slow and failure-prone. The core challenge is decoupling these calls with async orchestration while preserving correctness.

This walkthrough follows the Interview Framework. Use it as a guide, not a script.

This is intentionally a "general" interview question without one fixed answer. Interviewers usually look for good decomposition, idempotent workflows, failure handling, and practical trade-offs.