api-contract

Guide backward-compatible API contract changes across endpoints, DTOs, and OpenAPI/Swagger.

Updated Feb 18, 2026

Search Tags:#versioning #api #openapi #endpoints #dto #contract

Ready to run

npx skills add https://github.com/askaret/codex-skills --skill api-contract-askaret

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: api-contract
Source: https://github.com/askaret/codex-skills/tree/main/.agents/skills/api-contract
Command: npx skills add https://github.com/askaret/codex-skills --skill api-contract-askaret

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

API contracts govern how endpoints, DTOs, and clients interact; changes can introduce breaking behavior if not managed properly. This Skill guides safe, backward-compatible API evolution and ensures changes are well-documented and coordinated.

Core Features & Use Cases

Additive changes: introduce new fields or endpoints without removing existing ones, with a clear deprecation plan.
Consistent error handling and status codes across endpoints for predictable client behavior.
Documentation and client updates: keeps OpenAPI/Swagger, docs, and SDKs aligned with contract changes.

Quick Start

Outline a concrete API contract change and its backward-compatibility impact.

Frequently Asked Questions about api-contract

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

FAQPage Schema

How do I maintain backward compatibility when evolving API endpoints and DTOs?▼

To maintain backward compatibility during API evolution, apply additive changes by introducing new fields or endpoints without removing existing ones, while establishing a clear deprecation plan for outdated contract elements. This prevents breaking client code across versions.

What is the best way to keep OpenAPI and Swagger documentation aligned with API contract changes?▼

Keeping OpenAPI and Swagger documentation aligned requires standardizing error handling and status codes across endpoints for predictable client behavior, and systematically updating SDKs and docs to reflect additive contract changes and deprecation plans.

Can I remove deprecated fields from my API contract without breaking existing client versions?▼

Removing deprecated fields from an API contract risks breaking existing client versions. Instead of immediate removal, enforce additive changes and outline a structured deprecation plan that allows clients sufficient time to synchronize their code across versions.

How do I standardize error handling and status codes across multiple API endpoints?▼

Standardizing error handling and status codes across API endpoints involves enforcing consistent contract rules for predictable client behavior, ensuring that documentation and SDKs are updated simultaneously to reflect these standardized error responses.

When do I need to synchronize client code with API contract updates?▼

You need to synchronize client code with API contract updates whenever endpoint adjustments or DTO evolution occur. Coordinating these updates alongside OpenAPI documentation and deprecation plans ensures clients maintain consistent interaction with the API.