Type-safe callback URL requests

[jhoseph88]

Description:

When implementing an API that accepts callback URLs from clients, I'd like type-safe support for making requests to those callbacks using the schema defined in the OpenAPI spec's callbacks section.

Use case:

My server exposes an endpoint where clients register a callback URL:

paths:
  /subscribe:
    post:
      requestBody:
        content:
          application/json:
            schema:
              type: object
              properties:
                callbackUrl:
                  type: string
                  format: uri
      callbacks:
        onEvent:
          '{$request.body#/callbackUrl}':
            post:
              requestBody:
                content:
                  application/json:
                    schema:
                      $ref: '#/components/schemas/EventPayload'

Later, my server needs to POST to that callback URL with the EventPayload shape. I'd like openapi-fetch to help me make that outbound request with type checking against the callback schema.

Question:

Is this already achievable with the current types generated by openapi-typescript? If so, what's the recommended pattern?

If not, would you be open to supporting this use case? I'm happy to contribute but wanted to check interest and get design guidance before starting.

Context:

This is for server-to-server scenarios where openapi-fetch is used on the backend to call external services (including client-provided callback URLs).