Push relevant users if there's a knock on a room (MSC4506) by ara4n · Pull Request #19955 · element-hq/synapse

ara4n · 2026-07-14T15:49:01Z

Adds the recipient_permission push rule condition; matches if and only if the user the rules are being evaluated for has a power level >= that required to perform the power-levels action named by key.

Uses it in a new default override rule .org.matrix.msc4506.rule.knock (inserted before .m.rule.member_event, which otherwise suppresses all member events) so that members who can invite (i.e. accept the knock) are pushed when someone knocks.

Gated behind experimental_features.msc4506_enabled.

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Pull request is based on the develop branch
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Adds the recipient_permission push rule condition (unstable kind org.matrix.msc4506.recipient_permission): matches iff the user the rules are being evaluated for has a power level >= that required to perform the power-levels action named by `key`. Uses it in a new default override rule .org.matrix.msc4506.rule.knock (inserted before .m.rule.member_event, which otherwise suppresses all member events) so that members who can invite -- i.e. accept the knock (MSC2403) -- are pushed when someone knocks. Also lifts the member-event fast-path in the bulk evaluator for knocks, which otherwise evaluates rules for nobody (a knock's sender == state_key). Gated behind experimental_features.msc4506_enabled. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Uk8aPxHn3BHCe52L226jdG

Copilot

Pull request overview

Implements experimental MSC4506 push notifications for room knocks.

Changes:

Adds the recipient_permission condition and knock default rule.
Integrates recipient power levels and feature gating into push evaluation.
Adds Rust/Python tests, bindings, benchmarks, and changelog.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
`tests/push/test_push_rule_evaluator.py`	Tests the new condition.
`tests/push/test_bulk_push_rule_evaluator.py`	Tests knock notifications and gating.
`synapse/synapse_rust/push.pyi`	Updates Rust binding types.
`synapse/storage/databases/main/push_rule.py`	Passes the feature flag to rule filtering.
`synapse/push/bulk_push_rule_evaluator.py`	Computes recipient permissions and knock recipients.
`synapse/config/experimental.py`	Defines the experimental flag.
`rust/src/push/mod.rs`	Adds condition parsing and rule filtering.
`rust/src/push/evaluator.rs`	Evaluates recipient permissions.
`rust/src/push/base_rules.rs`	Defines the knock push rule.
`rust/benches/evaluator.rs`	Updates evaluator benchmarks.
`changelog.d/19955.feature`	Documents the feature.

Suppressed comments (2)

synapse/push/bulk_push_rule_evaluator.py:565

This lookup misses the room-version-specific creator power semantics. In v12 rooms, creators are deliberately absent from content.users, while get_user_power_level grants them CREATOR_POWER_LEVEL from the create event (synapse/event_auth.py:1133-1145). They therefore receive users_default here (normally 0) and are not notified when invite is 50 even though they can accept the knock. Calculate each recipient's level using the same create-event/auth-state logic as permission checks.

            recipient_power_level = _coerce_power_level(
                user_power_levels.get(uid, users_default_level), users_default_level
            )

synapse/push/bulk_push_rule_evaluator.py:565

recipient_permission remains active when msc4506_enabled is false: the Rust filter only removes the default MSC rule by ID, while a user-defined rule with this condition still receives a concrete power level and matches. Pass None while the feature is disabled so the condition is actually gated as described.

            recipient_power_level = _coerce_power_level(
                user_power_levels.get(uid, users_default_level), users_default_level
            )

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anoadragon453 · 2026-08-13T16:51:23Z

+        for key in list(action_power_levels.keys()):
+            level = action_power_levels[key]
+            if type(level) is not int:  # noqa: E721
+                try:
+                    action_power_levels[key] = int(level)
+                except (TypeError, ValueError):
+                    del action_power_levels[key]


Basically: if the power level is explicitly null (so None), then coerce it to 0, instead of ignoring it.

anoadragon453

Overall a useful addition, thank you!

I've done a rough review pass below.

anoadragon453 · 2026-08-13T16:03:06Z

@@ -0,0 +1 @@
+Push relevant users if there's a knock on a room (MSC4506).


Suggested change

Push relevant users if there's a knock on a room (MSC4506).

Implement experimental support for [MSC4506](https://github.com/matrix-org/matrix-spec-proposals/pull/4506): notify relevant users if there's a knock on a room.

anoadragon453 · 2026-08-13T16:36:27Z

+        .match_condition(&condition, Some("@bob:example.org"), None, None, None)
+        .unwrap());
+
+    // An action key we don't have a level for never matches.


It would be nice to have a test for the default behaviour of, say, invite not being defined in the m.room.power_levels state event.

Looks like the default behaviour is part of bulk_push_rule_evaluator.py.

anoadragon453 · 2026-08-13T16:42:00Z

+        # own level, for the `recipient_permission` condition. As above,
+        # non-integer levels in old room versions are interpreted as integers
+        # where possible and otherwise dropped.
+        action_power_levels = {


Suggested change

action_power_levels = {

# Note: membership state events do not use `state_default` as a fallback.

action_power_levels = {

anoadragon453 · 2026-08-13T16:43:01Z

+        for key in list(action_power_levels.keys()):
+            level = action_power_levels[key]
+            if type(level) is not int:  # noqa: E721
+                try:
+                    action_power_levels[key] = int(level)
+                except (TypeError, ValueError):
+                    del action_power_levels[key]


nit:

Suggested change

for key in list(action_power_levels.keys()):

level = action_power_levels[key]

if type(level) is not int: # noqa: E721

try:

action_power_levels[key] = int(level)

except (TypeError, ValueError):

del action_power_levels[key]

for key, level in enumerate(action_power_levels):

if type(level) is not int: # noqa: E721

try:

action_power_levels[key] = int(level)

except (TypeError, ValueError):

del action_power_levels[key]

anoadragon453 · 2026-08-13T16:45:32Z

+        users_default_level = _coerce_power_level(
+            power_levels.get("users_default", 0), 0
+        )
+        user_power_levels = power_levels.get("users", {})


This doesn't appear to take into account the fact that room creators have infinite power level in v12+ rooms, and are not included in m.room.power_levels->users.

anoadragon453 · 2026-08-13T16:48:29Z

This feature will need an experimental tracking issue before being merged.

anoadragon453 · 2026-08-13T16:51:23Z

+        for key in list(action_power_levels.keys()):
+            level = action_power_levels[key]
+            if type(level) is not int:  # noqa: E721
+                try:
+                    action_power_levels[key] = int(level)
+                except (TypeError, ValueError):
+                    del action_power_levels[key]


Basically: if the power level is explicitly null (so None), then coerce it to 0, instead of ignoring it.

ara4n requested a review from a team as a code owner July 14, 2026 15:49

ara4n changed the title ~~Add a default push rule notifying users who can act on a knock (MSC4506)~~ Push relevant users if there's a knock on a room (MSC4506) Jul 14, 2026

ara4n added 2 commits July 14, 2026 16:51

changelog

a218870

changelog.

b212bad

MadLittleMods added A-Push A-Knock labels Jul 14, 2026

ara4n mentioned this pull request Jul 14, 2026

Knocking element-hq/element-meta#43

Open

ara4n mentioned this pull request Jul 24, 2026

MSC4506: Push Rules for Knocking matrix-org/matrix-spec-proposals#4506

Open

anoadragon453 requested a balanced review from Copilot August 13, 2026 16:00

Copilot started reviewing on behalf of anoadragon453 August 13, 2026 16:00 View session

Copilot AI reviewed Aug 13, 2026

View reviewed changes

anoadragon453 requested changes Aug 13, 2026

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Push relevant users if there's a knock on a room (MSC4506) - #19955

Push relevant users if there's a knock on a room (MSC4506)#19955
ara4n wants to merge 3 commits into
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matthew/msc4506-knock-push-rule

ara4n commented Jul 14, 2026 •

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		@@ -0,0 +1 @@
		Push relevant users if there's a knock on a room (MSC4506).

	Push relevant users if there's a knock on a room (MSC4506).
	Implement experimental support for [MSC4506](https://github.com/matrix-org/matrix-spec-proposals/pull/4506): notify relevant users if there's a knock on a room.

	action_power_levels = {
	# Note: membership state events do not use `state_default` as a fallback.
	action_power_levels = {

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ara4n commented Jul 14, 2026 •

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