Design and explain your project architecture

Select one of your recent projects and draw a high-level architecture diagram. Walk through the system’s components and data stores, key APIs and data flows (sync vs. async, protocols), scaling and capacity planning, fault tolerance and backpressure, idempotency and retries, observability (logging/metrics/tracing), and security (authN/authZ, secrets, PII). Justify major trade-offs, discuss cost considerations, and propose concrete improvements. Be prepared to answer deep-dive follow-ups on specific components.