# design-an-api

> Designs the contract for an API change inside one codebase — a component's props, a function surface, URL or query para…

Designs the contract for an API change inside one codebase — a component's props, a function surface, URL or query parameters, an event payload, or a module boundary — through a discovery pass, an options document with one recommendation, a question round, and an adversarial validation round, with every element of the contract justified from one stated goal. Use when you want to design, shape, decide, or nail down an interface, contract, signature, or API change for a capability you can already describe, sized for roughly one pull request. Produces a design document and changes no code. Does not specify what a feature should do — use plan-a-feature. Does not plan delivery or sequencing — use plan-implementation. Does not assess the architecture of existing code — use architectural-analysis. Does not write the code — use tdd. Does not restructure existing code — use refactor. Runs its rounds without pausing for review; to review each round as it lands, use pairing.

- Type: Skill
- Made by: testdouble
- Category: Developer tools
- Formats: Skills
- Version: 24eddfa
- Source: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api
- Page: https://pluginboard.ai/skills/design-an-api

## Works with

- ChatGPT
- Claude
- Gemini
- GitHub Copilot
- Cursor
- Claude Code
- Codex
- Antigravity
- Gemini CLI
- Replit
- OpenClaw
- OpenCode
- Hermes Agent

## Install

### ChatGPT

In ChatGPT: Download the design-an-api folder and zip it, then Plugins → Skills → Create → Upload from your computer. Business and Enterprise plans.

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

### Claude

In Claude (web or desktop): Download the design-an-api folder and zip the folder itself, then upload it in Customize → Skills.

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

### Gemini

In Gemini: Download the design-an-api folder, then at gemini.google.com click Customize → Skills → Create → Upload and pick the folder (or a .zip of it).

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

### GitHub Copilot

Run in your terminal:

```shell
npx -y degit testdouble/han/han-coding/skills/design-an-api ~/.copilot/skills/design-an-api
```

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

### Cursor

Run in your terminal:

```shell
npx -y degit testdouble/han/han-coding/skills/design-an-api ~/.cursor/skills/design-an-api
```

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

### Claude Code

Run in your terminal:

```shell
npx -y degit testdouble/han/han-coding/skills/design-an-api ~/.claude/skills/design-an-api
```

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

Or all of Han Coding, in Claude Code:

```text
/plugin marketplace add testdouble/han
/plugin install han-coding@han
```

### Codex

Run in your terminal:

```shell
npx -y degit testdouble/han/han-coding/skills/design-an-api ~/.agents/skills/design-an-api
```

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

### Antigravity

In Antigravity: Copy the design-an-api folder into ~/.gemini/config/skills (Antigravity app and IDE) or ~/.gemini/antigravity-cli/skills (Antigravity CLI).

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

### Gemini CLI

Run in your terminal:

```shell
npx -y degit testdouble/han/han-coding/skills/design-an-api ~/.gemini/skills/design-an-api
```

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

### Replit

Run in your terminal:

```shell
npx -y degit testdouble/han/han-coding/skills/design-an-api .agents/skills/design-an-api
```

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

### OpenClaw

Run in your terminal:

```shell
npx -y degit testdouble/han/han-coding/skills/design-an-api ~/.openclaw/skills/design-an-api
```

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

### OpenCode

Run in your terminal:

```shell
npx -y degit testdouble/han/han-coding/skills/design-an-api ~/.config/opencode/skills/design-an-api
```

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

### Hermes Agent

Run in your terminal:

```shell
npx -y degit testdouble/han/han-coding/skills/design-an-api ~/.hermes/skills/design-an-api
```

View the folder on GitHub: https://github.com/testdouble/han/tree/HEAD/han-coding/skills/design-an-api

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From Pluginboard (https://pluginboard.ai).