We need a better way of disambiguating users with the same display name than mxids. (SPEC-221)

Right now we disambiguate via MXID on the client. This isn't great, as MXIDs are ugly and not supposed to be shown to normal end-users in glossy apps. It also increases clientside complexity in performing the disambiguation.

We can't reliably disambiguate via 3PIDs, as users may not want their 3PIDs to be leaked to the wider room.

Perhaps we can just disambiguate with some kind of custom suffix in the displayname as calculated by the server (e.g. an emoji, or matrix-org/matrix-spec-proposals#1/#2/#3). Or perhaps we can use the whole idea of groups to disambiguate (e.g. Matthew from the Matrix Core Team group, v. Matthew from Debian Core Team group) or whatever. Or even just list the homeserver friendly name that the user has come from?

TBD.

(Imported from https://matrix.org/jira/browse/SPEC-221)

(Reported by @ara4n)

No file, test, or implementation entry point is named. Start by reviewing the existing Matrix specification and the linked discussion context, then resolve whether server-calculated suffixes, groups, or homeserver names provide an acceptable disambiguation method without exposing 3PIDs. Done requires an agreed design rather than a defined code change.

Written by the indexing model from the issue text.