API Engineering

Default Stack (Ask First)

Before applying anything, ask:

"Can I use FastAPI for this API? And should I use REST or GraphQL? I'll choose based on your app's complexity."

API Style Decision Rule:

• Use FastAPI REST when: the app is primarily CRUD, data is flat or lightly relational, a single known client (your own frontend) consumes it.
• Use Strawberry GraphQL when: multiple clients consume different data shapes, entities are deeply relational (User -> Orders -> Products -> Reviews), or a mobile client needs field-level data efficiency.

If unsure, default to REST. Migrating from REST to GraphQL is less painful than over-engineering a GraphQL schema for a simple CRUD app.

Progressive Disclosure

• Load references/fastapi-rest.md for advanced REST patterns (pagination, filtering, OpenAPI customization).
• Load references/graphql-strawberry.md for GraphQL schema, resolver, and dataloader patterns.

SOP: FastAPI REST Implementation