api-and-interface-design

Design stable REST/GraphQL API contracts with consistent error semantics and boundary validation.

2|Updated Feb 16, 2026
One-click install
npx skills add https://github.com/d0whc3r/statsig-browser-extension --skill api-and-interface-design-d0whc3r
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: api-and-interface-design
Source: https://github.com/d0whc3r/statsig-browser-extension/tree/main/.agents/skills/api-and-interface-design
Command: npx skills add https://github.com/d0whc3r/statsig-browser-extension --skill api-and-interface-design-d0whc3r

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill helps you create stable, clear interfaces that reduce ambiguity and prevent consumers from depending on accidental behavior.

Core Features & Use Cases

  • Contract-first interface design: Define inputs/outputs and types before implementation to make the API self-documenting.
  • Consistent error semantics: Establish a single, predictable error format and status-code mapping so clients can handle failures reliably.
  • Boundary validation and safer evolution: Validate untrusted data at system edges and prefer additive, backward-compatible changes to avoid breaking consumers.

Quick Start

Use the api-and-interface-design skill to draft a contract-first REST API spec with consistent error responses, boundary validation rules, and a naming/pagination strategy for your next endpoint.

Frequently Asked Questions about api-and-interface-design

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

FAQPage Schema
How to design REST API contracts that prevent client misuse?▼

To design REST API contracts that prevent misuse, define inputs, outputs, and types before implementation to make the interface self-documenting and stable. This approach reduces ambiguity and prevents consumers from depending on accidental behavior.

What is the best way to handle REST API error semantics consistently?▼

The best way to handle REST API error semantics consistently is to establish a single, predictable error format with a clear status-code mapping. This ensures clients can handle failures reliably across all endpoints.

How do I validate untrusted inputs at system boundaries for an API?▼

Validate untrusted inputs at system boundaries by enforcing strict contract-first definitions for your REST or GraphQL endpoints. This ensures untrusted data is checked at the edges before entering internal module logic.

How to evolve a public API without breaking existing consumers?▼

To evolve a public API without breaking existing consumers, prefer additive, backward-compatible changes over modifying existing contracts. This approach minimizes accidental commitments and maintains stable interface boundaries.

Does contract-first interface design work for frontend-backend type contracts?▼

Yes, contract-first interface design works for frontend-backend type contracts and public component props. It defines predictable typing and naming conventions before implementation, ensuring stable module boundaries.

When should I establish interface contracts for module boundaries?▼

You should establish interface contracts for module boundaries when specifying REST or GraphQL endpoints, frontend-backend type contracts, or public component props to minimize misuse and reduce accidental commitments by consumers.