[Feature]: Join request links / knocking / join approvals from link

[Mikaela]

Is there an existing issue for this?

• I have searched the existing issues

Platform

all

App version

5.1.2

Feature

This is practically another take on #2543, I would like to create a link that creates a join approval (or knocking) request that would require admin approval before the user is added to the group.

I think this would help with group specific policies like friend group that doesn't want incognito mode or that share the link in wider group e.g. another platform that plans to move to SimpleX, without having to worry about the link getting leaked to unintendedly wider audience (the possibility of someone impersonating a group member is something occurring to me, but outside of scope of this request).

This is also supported in other platforms such as Telegram (blog) and Matrix.

[Mikaela]

Additional context: my friends are cats who come and go and I would like to keep the door open for them or at least have a method for letting them signal their wish to return rather than having to ask me with words which often raises the treshold for asking.

In Matrix I would use join rule knock_restricted, but I don't think that maps to SimpleX so well, especially when not using groups for all devices of both parties.

[epoberezkin]

The challenge with the current design is that group links are hosted by a specific member, often an unattended directory bot, and approval should be done by some other admins in the group.

We do consider re-design of how group links are managed, both to make them a formal part of group profile (not informally mentioned in group description as now) and to have joining redundancy, when the next link design will make new member connect to multiple admins at once. Knocking seems to be part of this redesign.