w3c/spec-generator ? reverse-engineered prompt

Build me a small TypeScript service that generates specification documents from a source URL. I want one simple HTTP endpoint that takes a draft URL and a generator type, starts with the ReSpec flow, and returns the finished spec content in the response.

It should run locally on a port I can choose, work with Node 22 or newer, and be easy to start and watch during development. If something is wrong with the request, return a clear JSON error message. If the generator finishes with warnings or processing issues, still return the generated output but include counts in response headers so I can tell something went wrong.

Please make it easy to add more generators later, not just ReSpec, and keep the code clean enough that I can follow it. If you need current docs for the spec tooling, feel free to look them up online.