MSC3958: Suppress notifications from message edits

proposals/3958-suppress-notifications-of-message-edits.md

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+# MSC3958: Suppress notifications from message edits
+
+[Event replacement](https://spec.matrix.org/v1.5/client-server-api/#event-replacements)
+(more commonly known as message edits) signals that a message is intended to
+be replaced with new content.
+
+This works well for fixing typos or other minor correction, but can cause
+spurious notifications if the event mentions a user's display name / localpart or
+if it includes `@room` (which is particularly bad in large rooms as every user
+is re-notified). This contributes to notification fatigue as the additional
+notifications contain no new information.
+
+## Proposal
+
+A new default push rule is added to suppress notifications due to [edits](https://spec.matrix.org/v1.5/client-server-api/#event-replacements).
+
+```json
+{
+    "rule_id": ".m.rule.suppress_edits",
+    "default": true,
+    "enabled": true,
+    "conditions": [
+        {
+            "kind": "event_match",
+            "key": "content.m.relates_to.rel_type",
+            "pattern": "m.replace"
+        }
+    ],
+    "actions": []
+}
+```
+
+This rule should be placed before the [`.m.rule.suppress_notices` rule](https://spec.matrix.org/v1.5/client-server-api/#default-override-rules)
+as the first non-master, non-user added override rule.
+
+It would match events such as those given in [event replacements](https://spec.matrix.org/v1.5/client-server-api/#event-replacements)
+portion of the spec:
+
+```json5
+{
+    "type": "m.room.message",
+    "content": {
+        "body": "* Hello! My name is bar",
+        "msgtype": "m.text",
+        "m.new_content": {
+            "body": "Hello! My name is bar",
+            "msgtype": "m.text"
+        },
+        "m.relates_to": {
+            "rel_type": "m.replace",
+            "event_id": "$some_event_id"
+        }
+    },
+    // ... other fields required by events
+}
+```
+
+Some users may be depending on notifications of edits. If a user would like to
+revert to the old behavior they can disable the `.m.rule.suppress_edits` push rule.
+
+## Potential issues
+
+### Editing mentions
+
+With this MSC it would no longer possible to edit a message to change who is going
+to be notified. For instance, if you write a message and then edit it to put another
+user pill in it, in this case the user would not be notified. Socially it seems more
+likely for the sender to send another message instead of editing:
+
+> @alice:example.com see above ^
+
+### Rule Ambiguity
+
+The rule is ambiguous (see [MSC3873](https://github.com/matrix-org/matrix-spec-proposals/pull/3873))
+due to the `.` in `m.relates_to` and could also match other, unrelated, events:
+
+```json5
+{
+    "type": "m.room.message",
+    "content": {
+        "body": "* Hello! My name is bar",
+        "msgtype": "m.text",
+        "m.new_content": {
+            "body": "Hello! My name is bar",
+            "msgtype": "m.text"
+        },
+        "m": {
+            "relates_to": {
+                "rel_type": "m.replace",
+                "event_id": "$some_event_id"
+            }
+        }
+    },
+    // ... other fields required by events
+}
+```
+
+(Note that `relates_to` being embedded inside of the `m`.)
+
+### Keeping notifications up-to-date
+
+Another issues is that mobile clients would no longer receive push notifications for
+message edits, which are currently used to update the text of on-screen notifications
+to show the updated content. The proposed push rule would mean that mobile clients would
+no longer receive this update, but showing slightly outdated text on a notification screen
+is only a minor impact and it would be better to separate when (& why) we send pushes vs.
+when we generate notifications.
+
+## Alternatives
+
+An alternative solution would be to add a push rule with no actions and a condition to
+check whether a notification should have been generated for the user in the original
+message.
+
+This should be placed as an override rule before the `.m.rule.contains_display_name`
+and the `.m.rule.roomnotif` [push rules](https://spec.matrix.org/v1.5/client-server-api/#push-rules).
+
+This would suppress duplicate notifications, while still allow for new notifications due
+to new mentions or keywords changing.
+
+## Security considerations
+
+None forseen.
+
+## Future extensions
+
+If message edits by other senders were allowed than it would be useful to
+know when your own message was edited, but this
+[is not currently allowed](https://spec.matrix.org/v1.5/client-server-api/#validity-of-replacement-events).
+A future MSC to define this behavior should take into account notifying
+users in this situation.
+
+## Unstable prefix
+
+The unstable prefix of `.com.beeper.suppress_edits` should be used in place of
+`.m.rule.suppress_edits`.
+
+## Dependencies
+
+N/A