---

name: api-contract-validation version: "2.0.0" description: API contract validation patterns for ensuring client-side models match backend JSON responses. Tech-stack agnostic. allowed-tools: Read, Grep, Glob, WebSearch

API Contract Validation

Purpose

Prevent bugs where client-side models don't match backend API responses.

Contract Location

docs/api-contracts/{feature}-{endpoint}.json

Schema Format

{
  "$schema": "api-contract-v1",
  "endpoint": "GET /api/items",
  "description": "What this endpoint does",
  "response": {
    "items": {
      "type": "array",
      "items": {
        "id": { "type": "string", "required": true },
        "name": { "type": "string", "required": true }
      }
    }
  }
}

Validation: required fields = non-nullable, optional = nullable. No ghost fields.