3914-call-notif.md

MSC3914: Matrix native group call push rule

MSC3401 defines how group calls can happen over Matrix. It adds a an m.call state event with an m.intent field which, if it has a value of m.ring or m.prompt, should cause a notification should be shown to the user. This MSC defines a new push rule for this scenario.

Proposal

A new push-rule condition is added with the name call_started. For this condition to be met the following conditions have to be met:

• m.intent must either be m.ring or m.prompt
• m.terminated must not be in the content
• the prev_content is either missing or includes m.terminated

This is a new push condition since the current push-rule system is not flexible enough for this to be built out of existing rules.

A new default underride rule is to be added:

{
    "rule_id": ".m.rule.room.call",
    "default": true,
    "enabled": true,
    "conditions": [
        {
            "kind": "event_match",
            "key": "type",
            "pattern": "m.call"
        },
        {
            "kind": "call_started"
        }
    ],
    "actions": [
        "notify", 
        {"set_tweak": "sound", "value": "default"}
    ]
}

This new push rule is inserted immediately after .m.rule.call.

Potential issues

Once we have state event E2EE all notifications will have to be handled client-side as the server won't see the content of events.

Alternatives

This could be implemented entirely client-side without any push rule though this presents an issue for mobile devices which can't sync all the time and therefore need to receive push notifications.

Unstable prefix

During development, .org.matrix.msc3914.rule.room.call and org.matrix.msc3914.call_started is to be used instead of .m.rule.room.call and call_started respectively.