Merge pull request #1819 from matrix-org/neilj/msc-remove-presence-lists

MSC:1819 Remove Presence Lists

proposals/1819-remove-presence-lists.md

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+# Remove references to presence lists
+
+[Presence](https://matrix.org/docs/spec/client_server/r0.4.0.html#id107) lists
+allow a given user the ability to subscribe to other users and be alerted to
+their current presence status.
+
+While spec'd, no established client has implemented support and the only server
+side implementation raises privacy concerns.
+
+The proposal is to simply remove references to presence lists with a view to
+revisiting the same ideas in the future.
+
+This MSC addresses
+[#1810](https://github.com/matrix-org/matrix-doc/issues/1810)
+
+## Proposal
+
+Presence lists seem like a good fit for ['MSC1769: Extensible profiles as
+rooms'](https://github.com/matrix-org/matrix-doc/pull/1769) proposal, meaning
+that the current design will most likely be superceded.
+
+Additionally, no major client has implemented the behaviour to date and the
+only server implementation of presence lists (Synapse) auto-accepts invites
+leading to privacy concerns in the wild.
+
+With this in mind the most pragmatic solution is to remove presence lists ahead
+of the r0 release.
+
+Specifically:-
+
+CS API: Remove
+* [POST
+  /_matrix/client/r0/presence/list/{userId}](https://matrix.org/docs/spec/client_server/r0.4.0.html#post-matrix-client-r0-presence-list-userid)
+* [GET
+  /_matrix/client/r0/presence/list/{userId}](https://matrix.org/docs/spec/client_server/r0.4.0.html#get-matrix-client-r0-presence-list-userid)
+
+SS API: Remove
+ * [m.presence_invite](https://matrix.org/docs/spec/server_server/unstable.html#m-presence-invite-schema)
+ * [m.presence_accept](https://matrix.org/docs/spec/server_server/unstable.html#m-presence-accept-schema)
+ * [m.presence_deny](https://matrix.org/docs/spec/server_server/unstable.html#m-presence-deny-schema)
+
+
+## Tradeoffs
+
+Ideally this proposal would also come with an alternative design for this
+functionality. Out of pragmatism the proposal only covers removal of what is
+there today.
+
+
+## Conclusions
+
+This is a common sense attempt to remove unused portions of the spec ahead of
+an r0 release. It does not suggest that the ability to subscribe to the
+presence of others is undesirable and assumes that this behvaiour will return
+again in some form.