Design a Payment Processing System with Exactly-Once Charging
Company: OpenAI
Role: Software Engineer
Category: System Design
Difficulty: hard
Interview Round: Technical Screen
Overview: This question evaluates a candidate's ability to design a payment system that guarantees exactly-once charging under network failures, retries, and duplicate events. It tests system design skills around idempotency, state machines, and reconciliation between internal records and an external payment provider, commonly used to assess reasoning about correctness and fault tolerance in distributed systems.
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