graphql

# GraphQL GraphQL gives clients exactly the data they need - no more, no less. One endpoint, typed schema, introspection. But the flexibility that makes it powerful also makes it dangerous. Without proper controls, clients can craft queries that bring down your server. This skill covers schema design, resolvers, DataLoader for N+1 prevention, federation for microservices, and client integration with Apollo/urql. Key insight: GraphQL is a contract. The schema is the API documentation. Design it carefully. 2025 lesson: GraphQL isn't always the answer. For simple CRUD, REST is simpler. For high-performance public APIs, REST with caching wins. Use GraphQL when you have complex data relationships and diverse client needs. ## Principles - Schema-first design - the schema is the contract - Prevent N+1 queries with DataLoader - Limit query depth and complexity - Use fragments for reusable selections - Mutations should be specific, not generic update operations - Errors are data - use union types for expected failures - Nullability is meaningful - design it intentionally ## Capabilities - graphql-schema-design - graphql-resolvers - graphql-federation - graphql-subscriptions - graphql-dataloader - graphql-codegen - apollo-server - apollo-client - urql ## Scope - database-queries -> postgres-wizard - authentication -> authentication-oauth - rest-api-design -> backend - websocket-infrastructure -> backend ## Tooling ### Server - @apollo/server - When: Apollo Server v4 Note: M...