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proposals/3032-presence-revamp.md

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+MSC3032: Thoughts on updating presence
+======================================
+
+This is deliberately a loose-form, draft MSC to note down my current thoughts
+on how we might improve the presence system and integrate it with
+profiles-as-rooms (MSC1769).
+
+## `PUT /_matrix/client/r0/presence/{userId}/status`
+`status_msg` becomes deprecated. In it's place there's a new state event in the
+user's MSC1769 profile room, `m.status`. It's not a field in the `m.profile`
+object because it's intended to be updated fairly frequently and we don't need
+to update the whole profile each time (this would be inefficient and risk data
+races).
+
+`presence` stays, with the additional value of `busy` as per MSC3026, but this
+endpoint is explicitly for the *user* setting their presence manually, eg. selecting
+'busy' or 'unavailable' from a checkbox in the UI.
+
+## `set_presence` in `/sync`
+This is differentiated from `PUT /_matrix/client/r0/presence/{userId}/status`
+by being explicitly for automatic updates from clients, eg.:
+ * A client supplies `unavailable` if it doesn't believe the user is paying attention
+   (eg. they haven't moved the mouse ina  while).
+ * A client supplies `busy` if the user is on a call in that client.
+
+## Effective presence
+The homeserver can then combine the multiple sources of presence information from
+the clients and the user-set value to determine an effective presence for the user.
+This is a black-box as far as the spec is concerned, but semantics will be along
+the lines of 'if any status is busy, the user is busy'.
+
+Question: if a user sets themselves 'busy', what status do they set when they're
+free again? 'online'?
+
+## Publishing presence
+Homeservers take the effective presence and publish it as an `m.presence` state
+event in the user's profile room. You subscribe to a user's presence by peeking
+into their profile room.
+
+m.presence events go away entirely after some deprecation period.
+
+Question: How would we restrict the set of people allowed to see presence
+   info (ie. assuming we allow a wider set of people to see the user's profile)
+Question: What happens if a user send an `m.presence`event to their profile room?
+          Should they be allowed to?
+
+## `GET /_matrix/client/r0/presence/{userId}/status`
+Also goes away.
+
+## Presence for the smartphone generation
+The presence status enum was designed in a time when smartphones were relatively
+new and it was still assumed that if you weren't at your computer, you were
+unavailable. This isn't true now we all carry our computers in our pockets.
+This probably requires only a small change in how we interpret the values though:
+ * `online`: Actively using a client right this moment
+ * `unavailable`: No particular status / default. It's assumed the user may be
+   available and respond if you message them, or maybe not.
+ * `busy`: Unavailable to talk.
+ * `offline`: It should be assumed that messages won't reach the user.