Design Points-from-Transactions Service
BrexSoftware Engineer · Technical Screen
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This question evaluates system design and distributed-systems competency, focusing on transaction processing, idempotency and deduplication, monetary precision and rounding, consistency models, data modeling, and operational controls like observability and fraud prevention.
Design a scalable service that converts purchase transactions in USD to loyalty points at a fixed rate of 1 dollar = 1.5 points. Cover API design (ingest transactions, query balances, redeem points), idempotency and deduplication, precision and rounding strategy, consistency model (eventual vs. strong), data model and schema, prevention of double counting and fraud, real-time and batch processing, backfill and correction flows, scaling and partitioning strategy, observability, and rollout/testing plans.
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