What problem does it solve? Storefronts in composable commerce architectures often make 10+ API calls per page load across catalog, inventory, cart, and CMS services, creating latency, inconsistent authentication, and duplicated cross-cutting logic. This Skill provides patterns for building a single API gateway that unifies these services behind one entry point. ## Core Features & Use Cases - GraphQL Federation with Apollo Router: Compose catalog, inventory, and cart subgraphs into a unified supergraph using Rover CLI, with @key, @extends, and @external directives for shared entity types. - REST BFF with Fastify: Build composite endpoints (e.g., /api/pdp/:id) that call multiple upstream services in parallel with Promise.allSettled and graceful fallbacks for non-critical services. - Cross-Cutting Concerns at the Gateway: Apply JWT RS256 authentication, Redis-backed rate limiting, response caching, explicit CORS origins, and OpenTelemetry distributed tracing without modifying each microservice. - Use Case: A fashion retailer migrating from a monolith to composable commerce uses this Skill to consolidate 8-12 storefront API calls into single BFF endpoints, enforce per-user rate limits, and propagate trace context to all downstream services. ## Quick Start Ask the AI to build a Fastify BFF that aggregates catalog, inventory, and CMS services into a product detail endpoint with JWT auth and Redis rate limiting.
