OpenAPIs using remote functions

Describe the problem

Remote functions are a blast to work with in SvelteKit. But of course, there is a whole world out there beyond SvelteKit. So often one would want to expose a REST API. OpenAPI is a well established standard, not only providing automated documentation solutions, but also automated SDK generation in many languages.

Describe the proposed solution

Since remote functions already compile to endpoints, I wondered if it may be feasible to support generating REST APIs like this:

// src/openapi.server.ts
import { 
  createFooCommand,
  readFooQuery,
  updateFooCommand,
  deleteFooCommand
} from '$lib/remotes/foo.remote.ts';
import { 
  createBarCommand,
  readBarQuery,
  updateBarCommand,
  deleteBarCommand
} from '$lib/remotes/bar.remote.ts';

export const spec = {
  foo: {
    POST: createFooCommand
       .endpoint({
           // additional options passed here
       }),
    GET: readFooCommand,
    PUT: updateFooCommand
    DELETE: deleteFooCommand
  },
  bar: {
     // etc
  }
}

Alternatives considered

Currently, as far as I know, one can either:

1. Manually write endpoint wrappers for remote functions and somehow generate and serve an openapi.json file
2. Use a fallback method handler to dynamically generate the full API and serve the openapi.json

Importance

would make my life easier

Additional Information

I'm not exactly sure how this sort of proposal plays with guards such as proposed here: https://github.com/sveltejs/kit/issues/14612

Start by reviewing how remote functions compile to endpoints and the fallback method handler described in the issue. Compare the proposal with the guard discussion in issue 14612. Done would require a decided approach for exposing remote functions as REST endpoints and generating and serving an openapi.json specification.