In particular: are rooms with an invite or knock join rule returned?

In particular: are rooms with an invite or knock join rule returned?

If the user has a pending invite they can see the room: https://github.com/matrix-org/synapse/blob/6236afc621925cd01b67cf026cb28b4f7bd0384e/synapse/handlers/room_summary.py#L585-L606

Knockable rooms are also shown: https://github.com/matrix-org/synapse/blob/6236afc621925cd01b67cf026cb28b4f7bd0384e/synapse/handlers/room_summary.py#L565-L573

This was definitely the intention of those lines in MSC2946, I can try to dig up old threads in the PR if you want.

Thanks for the clarifications @clokep.

It's somewhat surprising to me that changing the join rule to knock means that more information is returned to uninvited users than for an invite room, and it feels like that might catch users off-guard too?

It's somewhat surprising to me that changing the join rule to knock means that more information is returned to uninvited users than for an invite room, and it feels like that might catch users off-guard too?

I think knock rooms are generally thought to be "findable" and that's why they're returned. This fits pretty well into the description of discoverability given in MSC2403. If a room is knockable the implication is that you want people to find it, but they must ask to join it.

(I should also note that if the user has a pending invite the room will be returned regardless of the join rule, which I think is reasonable.)

Let's take discussion of whether that behaviour is correct to #1186.

Conclusion of #1186 was that we're fine for knockable rooms to be returned by /hierarchy. So this is just a spec clarification issue.

So this was actually defined in MSC3173:

This MSC [...] formalizes who can access the stripped state of a room in future cases.

Potential ways that a user might be able to join a room include, but are not limited to, the following mechanisms:

• A room that has join_rules set to public or knock.
• A room that the user is in possession of an invite to (regardless of the join_rules).

Seems like #3606 missed this part of the MSC?

Note that Synapse also returns rooms with world_readable set to true. This seems ok since the state is allowed by anyone, but isn't well defined and is mentioned in MSC3173 also, probably should have been a separate bullet though.