system-design

Design system architecture, choose patterns, and document trade-offs. Covers monolith vs microservices, modular monoliths, event-driven design, API contracts (OpenAPI), data modeling, caching strategy, and Architecture Decision Records (ADRs). Use this skill whenever the user mentions system design, architecture, HLD/LLD, microservices, monolith, event-driven, CQRS, API design, database choice, caching, or asks how the pieces of a system fit together, even if they only say "how should I structure this" or "design the backend for...". Not for framework setup or code scaffolding (see web-app-development), deploy pipelines (see devops-delivery), or scoping what to build (see product-planning).