This is a similar thing to ENG-11106 - here it allows me to satisfy Flow without complex type mappings

I don't think it matters, because we never check members' permissions, but if we want to be exact, we could rely on +role?: 'member' | 'admin', when choosing the role. I think we can leave it as it is, but it should be a conscious decision.

Ugh, hard.

As the first approximation, we could at least avoid breaking anything. We could do that by determining thread invitees by computing member IDs with the invitee role, and passing it to createMembersAndCurrentUser. It will make sure we don't promote a user by accident.

If we want to be exact, we would need to stop using the lightweight sync. The problem with the lighweight sync is that the inbox API doesn't return member or invitee IDs - just the admin IDs, for some reason. So based on the response, we can't reliably update members or invitees.

The current solution isn't ideal, because it is possible that a new user was added or invited to a thread, and the only way for us to learn about it is to open the thread. The only real impact of this is during the search. But if we want to have a proper solution, then we need to perform the full sync on every app open - or even more often, which would make the app unusable.

Addressed in D15436