umi Agent Skills & AI Rules

## How to add a built-in feature plugin?

1. add a ts file to `packages/preset-umi/src/features/${name}/${name}.ts`, the plugin api doc is in `docs/docs/docs/api/plugin-api.md`. 

Sample code:

```ts
import { IApi } from '../../types';
export default (api: IApi) => {
  api.describe({
    key: '404',
  });
};
```

2. Add to `packages/preset-umi/src/index.ts` to the `features` part.