Thanks for jumping in @mbondarenko! I got quite busy, glad to see you were on hand to answer.
@jbdoster the advice you were given is sound, if you set the _sp_duid cookie yourself that’s as close as you can get to floating domain_userid - but cookies are unreliable on AMP, which is why the primary recommended AMP strategy for user identification is to map across the available ids, with an ‘at least once mapped’ assumption. It’s quite awkward but it’s what the platform gives us.
So this feature isn’t not out of the question, it’s just one that still needs some ironing out.
If you’re keen to get something in place that passes the session id to AMP, it is possible to instrument some JS which retrieves the session id using the JS tracker’s
getDomainUserInfo callback method, then pass that in the querystring to AMP, and parse it on your AMP page to pass into a custom context. Also, there’s an AMP issue to allow session ids on AMP itself, which is something I’m keen to see happen - so giving that a thumbs up can’t do any harm if you’re interested in it. (it seems there is intent to do it, at least!)
Hope that’s helpful.