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api-and-interface-design

Design stable API and module interfaces with contract-first specifications.

Updated Aug 27, 2026
Search Tags:#design#api#interfaces#validation#rest#graphql#contracts
One-click install
npx skills add https://github.com/Coldaine/agent-skills-vscode --skill api-and-interface-design-coldaine
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: api-and-interface-design
Source: https://github.com/Coldaine/agent-skills-vscode/tree/main/skills/api-and-interface-design
Command: npx skills add https://github.com/Coldaine/agent-skills-vscode --skill api-and-interface-design-coldaine

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Design stable, well-documented interfaces that prevent misuse and reduce breaking changes across APIs, module contracts, and inter-service boundaries.

Core Features & Use Cases

  • Contract-first design: define interfaces before implementation to establish a clear spec.
  • Consistent error semantics: unify error shapes and status mappings across endpoints for predictable integrations.
  • Boundary validation: enforce validation at API boundaries to prevent untrusted inputs from leaking into internal logic.

Quick Start

Draft the initial API contract and interface definitions before coding the endpoints.

Frequently Asked Questions about api-and-interface-design

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

FAQPage Schema
What is contract-first API design and when do I need it?▼

Contract-first API design means defining stable interface specifications before coding endpoints. You need it to prevent misuse and reduce breaking changes across REST or GraphQL boundaries before implementation begins.

How do I design consistent error semantics for REST and GraphQL APIs?▼

Design consistent error semantics by unifying error shapes and status mappings across all endpoints. This ensures predictable integrations by standardizing how failures are represented across REST or GraphQL interfaces.

Where should I enforce validation in an API architecture?▼

Enforce validation at API boundaries to prevent untrusted inputs from leaking into internal logic. Boundary validation ensures predictable behavior by intercepting invalid data before it reaches module contracts or core services.

What's the best way to prevent breaking changes in frontend-backend boundaries?▼

Prevent breaking changes by designing well-documented interfaces and stable module contracts before implementation. Establishing a clear spec upfront reduces integration friction and protects frontend-backend boundaries from shifting expectations.

Does this approach work for both REST and GraphQL endpoint design?▼

Yes, this approach applies to designing stable interfaces for both REST and GraphQL endpoints. It enforces contract-first design and boundary validation uniformly across inter-service boundaries and frontend-backend integrations.

How do I start designing an API contract before coding the endpoints?▼

Start by drafting the initial API contract and defining module interface boundaries before writing endpoint code. This establishes a clear specification that guides implementation and enforces predictable integrations.

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