penpot-plugins/docs/create-api.md

Add your API in libs/plugins-runtime/src/lib/api/index.ts.

Try to use zod to validate the input an output, for example:

{
  sum: z.function()
    .args(z.number(), z.number())
    .returns(z.number())
    .implement((callback, time) => {
      setTimeout(callback, time);
    });
}

Update /libs/plugins-runtime/src/lib/api/index.d.ts.