Clojurians Log v2

The returned value for opening a portal is an opaque :id... but somewhere in the deep state of portal the atom/buffer must be kept. Can I find it?

I think you might be looking for https://cljdoc.org/d/djblue/portal/0.59.1/api/portal.api#selected which accepts a session as its argument. The value returned by portal.api/open is the session, but you can also get all your sessions via portal.api/sessions.