type: "Stack layer"
title: "Contracts and interfaces"
description: "Authoritative, machine-readable descriptions of what a capability is and how to call it."
tags: [stack, contracts, standards]
generated: { by: human:crpage, at: 2026-07-09T09:44:00Z }
status: stable

Role in the stack

The base layer: formal, machine-readable interface contracts. OpenAPI describes HTTP APIs; AsyncAPI describes message-driven ones; GraphQL exposes a typed query layer; gRPC/protobuf define typed RPC; JSON Schema validates arguments; Arazzo describes multi-step workflows over them.

Principle

A schema-valid call is not the same as a valid or authorised action — contracts give form, not authority or correctness. Prefer authoritative published contracts over inferred schemas.

Relates to: Understanding and grounding, Control plane.