Which messages have been read? #14
Description
Both in email and in chat clients like Matrix and Signal, it is common UX to show which messages remain unread, or what is the last read message. Some messaging systems (notably email) keep this info private to the reader, while others (e.g. Matrix) share this info among the channel readers, or make it configurable (e.g. Signal).
I have previously approached this by sending ActivityStreams notification about a new message to the receiver's inbox, and assuming that the message is unread as long as the notification remains in the inbox. This is used to show an indication of unread messages in the UI of the app.
It would also be possible to store this info in an associated document, or in the channel itself by attaching a fictional predicate meeting:readAt or similar.
Has this been addressed by the specification or by the implementations?