How can I integrate the remix request with my express/koa/whatever middleware ?

[Nick-Minutello]

I really like the BYO server design of remix.

We have an existing koa server, serving a public rest api & now we also have some UI. I like that they can be hosted on the same instance.

However, I have been struggling to figure out how leverage/integrate remix server-side code with the existing koa middleware:
e.g.

1. We have koa middleware that handles authentication. We just want to access the user object that has been placed on the koa request.
2. One could imagine using something like passport to do the same.
3. We have existing middleware doing distributed request tracing - that appears to be working fine, but we don't have access to the trace-id and span-id from within the remix load/action.

Obviously, any such integration would be server-specific.
Presumably, this could be handled via the various adapters.

Has anyone managed a work-around?