api-contract

Enforce typed API contracts between FastAPI Pydantic and Next.js Zod schemas.

1|Updated Sep 14, 2025
One-click install
npx skills add https://github.com/CleanExpo/DR-NRPG --skill api-contract-cleanexpo
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: api-contract
Source: https://github.com/CleanExpo/DR-NRPG/tree/main/.skills/custom/api-contract
Command: npx skills add https://github.com/CleanExpo/DR-NRPG --skill api-contract-cleanexpo

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill prevents inconsistencies and runtime errors between your FastAPI backend API and your Next.js frontend by enforcing strict, typed API contracts.

Core Features & Use Cases

  • Typed Contracts: Enforces Pydantic models on the backend and Zod schemas on the frontend for all API responses.
  • Schema Synchronization: Ensures frontend and backend schemas match, preventing drift.
  • Error Handling: Standardizes error response formats and documentation.
  • Use Case: When a new API endpoint is created, this Skill ensures that the response structure defined in FastAPI's Pydantic model is precisely matched by a Zod schema on the frontend, guaranteeing type safety and predictable data handling.

Quick Start

Apply the api-contract skill to enforce typed API contracts between the FastAPI backend and Next.js frontend.

Frequently Asked Questions about api-contract

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I enforce API contracts between FastAPI and Next.js?

To enforce API contracts between FastAPI and Next.js, you apply typed schemas using Pydantic on the backend and Zod on the frontend. This ensures response structures match precisely, preventing schema drift and runtime errors.

What is the best way to keep Pydantic and Zod schemas synchronized?

Synchronizing Pydantic and Zod schemas requires using strict schema location conventions and OpenAPI documentation. This approach guarantees that frontend and backend models match, preventing data drift and ensuring predictable type safety.

How do I standardize error response formats in a FastAPI and Next.js stack?

Standardizing error response formats involves defining strict API contracts for errors using Pydantic and Zod. This ensures the FastAPI backend and Next.js frontend handle and document error responses consistently across all endpoints.

Can I use this API contract approach with existing FastAPI endpoints?

Yes, you can apply this API contract approach to existing FastAPI endpoints. It enforces typed Pydantic models for responses and matches them with Zod schemas on the Next.js frontend to guarantee type safety and predictable data handling.

Why do I need typed API contracts for my Next.js and FastAPI application?

Typed API contracts are needed to prevent inconsistencies and runtime errors between your FastAPI backend and Next.js frontend. By enforcing matching Pydantic and Zod schemas, you guarantee type safety and predictable data handling.

Does this approach cover API versioning strategies for FastAPI and Next.js?

Yes, this API contract approach covers versioning strategies. It uses schema conventions and OpenAPI documentation to manage API versions, ensuring consistency and preventing runtime errors as your FastAPI and Next.js application evolves.