Implement MSC3958: suppress notifications from edits (#14960)

Co-authored-by: Brad Murray <brad@beeper.com>
Co-authored-by: Nick Barrett <nick@beeper.com>

Copy the suppress_edits push rule from Beeper to implement MSC3958.

https://github.com/beeper/synapse/blame/9415a1284b1bfb558bd66f28c24ca1611e6c6fa2/rust/src/push/base_rules.rs#L98-L114

9 files changed, 76 insertions, 2 deletions

diff --git a/changelog.d/14960.feature b/changelog.d/14960.feature
new file mode 100644
index 0000000000..b9bb331273
--- /dev/null
+++ b/changelog.d/14960.feature
@@ -0,0 +1 @@
+Experimental support to suppress notifications from message edits ([MSC3958](https://github.com/matrix-org/matrix-spec-proposals/pull/3958)).
diff --git a/rust/benches/evaluator.rs b/rust/benches/evaluator.rs
index 859d54961c..35f7a50bce 100644
--- a/rust/benches/evaluator.rs
+++ b/rust/benches/evaluator.rs
@@ -170,6 +170,7 @@ fn bench_eval_message(b: &mut Bencher) {
         false,
         false,
         false,
+        false,
     );
 
     b.iter(|| eval.run(&rules, Some("bob"), Some("person")));
diff --git a/rust/src/push/base_rules.rs b/rust/src/push/base_rules.rs
index 49add4e951..e9af26dd4f 100644
--- a/rust/src/push/base_rules.rs
+++ b/rust/src/push/base_rules.rs
@@ -63,6 +63,23 @@ pub const BASE_PREPEND_OVERRIDE_RULES: &[PushRule] = &[PushRule {
 }];
 
 pub const BASE_APPEND_OVERRIDE_RULES: &[PushRule] = &[
+    // We don't want to notify on edits. Not only can this be confusing in real
+    // time (2 notifications, one message) but it's especially confusing
+    // if a bridge needs to edit a previously backfilled message.
+    PushRule {
+        rule_id: Cow::Borrowed("global/override/.com.beeper.suppress_edits"),
+        priority_class: 5,
+        conditions: Cow::Borrowed(&[Condition::Known(KnownCondition::EventMatch(
+            EventMatchCondition {
+                key: Cow::Borrowed("content.m.relates_to.rel_type"),
+                pattern: Some(Cow::Borrowed("m.replace")),
+                pattern_type: None,
+            },
+        ))]),
+        actions: Cow::Borrowed(&[Action::DontNotify]),
+        default: true,
+        default_enabled: true,
+    },
     PushRule {
         rule_id: Cow::Borrowed("global/override/.m.rule.suppress_notices"),
         priority_class: 5,
diff --git a/rust/src/push/evaluator.rs b/rust/src/push/evaluator.rs
index da6f704c0e..ec7a8c4453 100644
--- a/rust/src/push/evaluator.rs
+++ b/rust/src/push/evaluator.rs
@@ -523,7 +523,7 @@ fn test_requires_room_version_supports_condition() {
     };
     let rules = PushRules::new(vec![custom_rule]);
     result = evaluator.run(
-        &FilteredPushRules::py_new(rules, BTreeMap::new(), true, false, true, false),
+        &FilteredPushRules::py_new(rules, BTreeMap::new(), true, false, true, false, false),
         None,
         None,
     );
diff --git a/rust/src/push/mod.rs b/rust/src/push/mod.rs
index 7e449f2433..3c4f876cab 100644
--- a/rust/src/push/mod.rs
+++ b/rust/src/push/mod.rs
@@ -419,6 +419,7 @@ pub struct FilteredPushRules {
     msc3381_polls_enabled: bool,
     msc3664_enabled: bool,
     msc3952_intentional_mentions: bool,
+    msc3958_suppress_edits_enabled: bool,
 }
 
 #[pymethods]
@@ -431,6 +432,7 @@ impl FilteredPushRules {
         msc3381_polls_enabled: bool,
         msc3664_enabled: bool,
         msc3952_intentional_mentions: bool,
+        msc3958_suppress_edits_enabled: bool,
     ) -> Self {
         Self {
             push_rules,
@@ -439,6 +441,7 @@ impl FilteredPushRules {
             msc3381_polls_enabled,
             msc3664_enabled,
             msc3952_intentional_mentions,
+            msc3958_suppress_edits_enabled,
         }
     }
 
@@ -476,6 +479,11 @@ impl FilteredPushRules {
                 {
                     return false;
                 }
+                if !self.msc3958_suppress_edits_enabled
+                    && rule.rule_id == "global/override/.com.beeper.suppress_edits"
+                {
+                    return false;
+                }
 
                 true
             })
diff --git a/stubs/synapse/synapse_rust/push.pyi b/stubs/synapse/synapse_rust/push.pyi
index c0af2af3df..754acab2f9 100644
--- a/stubs/synapse/synapse_rust/push.pyi
+++ b/stubs/synapse/synapse_rust/push.pyi
@@ -47,6 +47,7 @@ class FilteredPushRules:
         msc3381_polls_enabled: bool,
         msc3664_enabled: bool,
         msc3952_intentional_mentions: bool,
+        msc3958_suppress_edits_enabled: bool,
     ): ...
     def rules(self) -> Collection[Tuple[PushRule, bool]]: ...
 
diff --git a/synapse/config/experimental.py b/synapse/config/experimental.py
index d2d0270ddd..53c0682dfd 100644
--- a/synapse/config/experimental.py
+++ b/synapse/config/experimental.py
@@ -173,3 +173,8 @@ class ExperimentalConfig(Config):
         self.msc3952_intentional_mentions = experimental.get(
             "msc3952_intentional_mentions", False
         )
+
+        # MSC3959: Do not generate notifications for edits.
+        self.msc3958_supress_edit_notifs = experimental.get(
+            "msc3958_supress_edit_notifs", False
+        )
diff --git a/synapse/storage/databases/main/push_rule.py b/synapse/storage/databases/main/push_rule.py
index 466a1145b7..9b2bbe060d 100644
--- a/synapse/storage/databases/main/push_rule.py
+++ b/synapse/storage/databases/main/push_rule.py
@@ -90,6 +90,7 @@ def _load_rules(
         msc3664_enabled=experimental_config.msc3664_enabled,
         msc3381_polls_enabled=experimental_config.msc3381_polls_enabled,
         msc3952_intentional_mentions=experimental_config.msc3952_intentional_mentions,
+        msc3958_suppress_edits_enabled=experimental_config.msc3958_supress_edit_notifs,
     )
 
     return filtered_rules
diff --git a/tests/push/test_bulk_push_rule_evaluator.py b/tests/push/test_bulk_push_rule_evaluator.py
index 3b2d082dcb..7567756135 100644
--- a/tests/push/test_bulk_push_rule_evaluator.py
+++ b/tests/push/test_bulk_push_rule_evaluator.py
@@ -19,7 +19,7 @@ from parameterized import parameterized
 
 from twisted.test.proto_helpers import MemoryReactor
 
-from synapse.api.constants import EventContentFields
+from synapse.api.constants import EventContentFields, RelationTypes
 from synapse.api.room_versions import RoomVersions
 from synapse.push.bulk_push_rule_evaluator import BulkPushRuleEvaluator
 from synapse.rest import admin
@@ -370,3 +370,43 @@ class TestBulkPushRuleEvaluator(HomeserverTestCase):
                 },
             )
         )
+
+    @override_config({"experimental_features": {"msc3958_supress_edit_notifs": True}})
+    def test_suppress_edits(self) -> None:
+        """Under the default push rules, event edits should not generate notifications."""
+        bulk_evaluator = BulkPushRuleEvaluator(self.hs)
+
+        # Create & persist an event to use as the parent of the relation.
+        event, context = self.get_success(
+            self.event_creation_handler.create_event(
+                self.requester,
+                {
+                    "type": "m.room.message",
+                    "room_id": self.room_id,
+                    "content": {
+                        "msgtype": "m.text",
+                        "body": "helo",
+                    },
+                    "sender": self.alice,
+                },
+            )
+        )
+        self.get_success(
+            self.event_creation_handler.handle_new_client_event(
+                self.requester, events_and_context=[(event, context)]
+            )
+        )
+
+        # Room mentions from those without power should not notify.
+        self.assertFalse(
+            self._create_and_process(
+                bulk_evaluator,
+                {
+                    "body": self.alice,
+                    "m.relates_to": {
+                        "rel_type": RelationTypes.REPLACE,
+                        "event_id": event.event_id,
+                    },
+                },
+            )
+        )