GraphQL API Development for Mobile & SPA Applications

We're migrating from a legacy REST API to GraphQL to serve our React Native mobile app and React SPA. Need a senior developer to build it from scratch.

Scope

1. Schema Design
— Type-first schema: User, Product, Order, Review, Notification
— Input types and mutation definitions
— Custom scalars (Date, JSON, Upload)
— Enum types for status fields

2. Implementation
— Apollo Server 4 with Express middleware
— DataLoader for N+1 query prevention
— JWT authentication via context
— Field-level authorization (middleware / directives)
— Subscriptions via WebSocket (order status, notifications)

3. Performance & Quality
— Query depth/complexity limiting
— Persisted queries for mobile clients
— PostgreSQL queries optimized (EXPLAIN ANALYZE review)
— Unit tests for resolvers (Jest + Supertest)
— Apollo Studio integration

4. Documentation & Handoff
— Schema documentation with descriptions on all types
— Postman/Insomnia collection
— Migration guide from REST endpoints