The browser knows the xid
since we generate/assign it in the wrapper app (even if it's just stored in localstorage and never goes to a server).
Using the xid
provided in url query param, we can get user details, including the conversation-specific participant ID in .ptpt.pid
(see attached for full response)
https://pol.is/api/v3/participationInit?conversation_id=4kjz5rrrfe&pid=mypid&xid=12334552
// snip