Designing a Subscription-Box E-Commerce System
A production-grade system-design walkthrough for subscription-box e-commerce: staggered recurring billing with idempotency keys, dunning with exponential backoff, preference-driven curation as constraint satisfaction, atomic optimistic inventory reservation, event-driven saga (billing → curation → fulfilment) over per-subscriber Kafka partitions, cutoff-aware APIs, PCI tokenisation at the gateway boundary, three-way reconciliation, and shadow →…
Designing a System for Black Friday-Scale Traffic (50x Spikes, 48-Hour Window)
A production-grade system-design walkthrough for absorbing a 50x, 48-hour Black Friday traffic spike: predictive pre-scaling and horizontal auto-scaling, virtual waiting rooms for graceful load shedding, circuit breakers and bulkheads around the payment gateway, atomic conditional inventory decrement, a Kafka-buffered async order pipeline, layered CDN+cache+read-replica offload protecting the primary database, and…
Detecting a Compromised Public-Figure Account from Anomalous Posting Behavior
A production-grade system-design walkthrough for detecting compromised public-figure accounts from anomalous posting behaviour: per-account behavioural baselining across temporal, content, session, and interaction features; ensemble risk scoring with high-confidence rule overrides; a tiered response ladder (passive log → flag → step-up auth → temporary hold and page); human-in-the-loop review; and fail-toward-caution…
