- Stabilise support for [MSC3966](https://github.com/matrix-org/matrix-spec-proposals/pull/3966): `event_property_contains` push condition. ([\#15187](https://github.com/matrix-org/synapse/issues/15187))
- Implement [MSC2659](https://github.com/matrix-org/matrix-spec-proposals/pull/2659): application service ping endpoint. Contributed by Tulir @ Beeper. ([\#15249](https://github.com/matrix-org/synapse/issues/15249))
- Allow loading `/register/available` endpoint on workers. ([\#15268](https://github.com/matrix-org/synapse/issues/15268))
Bugfixes
--------
- Fix a long-standing bug in which the user directory would assume any remote membership state events represent a profile change. ([\#14755](https://github.com/matrix-org/synapse/issues/14755), [\#14756](https://github.com/matrix-org/synapse/issues/14756))
- Implement [MSC3873](https://github.com/matrix-org/matrix-spec-proposals/pull/3873) to fix a long-standing bug where properties with dots were handled ambiguously in push rules. ([\#15190](https://github.com/matrix-org/synapse/issues/15190))
- Faster joins: Fix a bug introduced in Synapse 1.66 where spurious "Failed to find memberships ..." errors would be logged. ([\#15232](https://github.com/matrix-org/synapse/issues/15232))
- Fix long-standing error when sending message into deleted room. ([\#15235](https://github.com/matrix-org/synapse/issues/15235))
Updates to the Docker image
---------------------------
- Ensure the Dockerfile builds on platforms that don't have a `cryptography` wheel. ([\#15239](https://github.com/matrix-org/synapse/issues/15239))
- Mirror images to the GitHub Container Registry (`ghcr.io/matrix-org/synapse`). ([\#15281](https://github.com/matrix-org/synapse/issues/15281), [\#15282](https://github.com/matrix-org/synapse/issues/15282))
Improved Documentation
----------------------
- Add a missing endpoint to the workers documentation. ([\#15223](https://github.com/matrix-org/synapse/issues/15223))
Internal Changes
----------------
- Add additional functionality to declaring worker types when starting Complement in worker mode. ([\#14921](https://github.com/matrix-org/synapse/issues/14921))
- Add `Synapse-Trace-Id` to `access-control-expose-headers` header. ([\#14974](https://github.com/matrix-org/synapse/issues/14974))
- Improve performance of creating and authenticating events. ([\#15195](https://github.com/matrix-org/synapse/issues/15195))
- Make the `HttpTransactionCache` use the `Requester` in addition of the just the `Request` to build the transaction key. ([\#15200](https://github.com/matrix-org/synapse/issues/15200))
- Improve log lines when purging rooms. ([\#15222](https://github.com/matrix-org/synapse/issues/15222))
- Add topic and name events to group of events that are batch persisted when creating a room. ([\#15229](https://github.com/matrix-org/synapse/issues/15229))
- Improve type hints. ([\#15230](https://github.com/matrix-org/synapse/issues/15230), [\#15231](https://github.com/matrix-org/synapse/issues/15231), [\#15238](https://github.com/matrix-org/synapse/issues/15238))
- Move various module API callback registration methods to a dedicated class. ([\#15237](https://github.com/matrix-org/synapse/issues/15237))
- Configure GitHub Actions for merge queues. ([\#15244](https://github.com/matrix-org/synapse/issues/15244))
- Add schema comments about the `destinations` and `destination_rooms` tables. ([\#15247](https://github.com/matrix-org/synapse/issues/15247))
- Bump hiredis from 2.2.1 to 2.2.2. ([\#15252](https://github.com/matrix-org/synapse/issues/15252))
- Bump serde from 1.0.152 to 1.0.155. ([\#15253](https://github.com/matrix-org/synapse/issues/15253))
- Bump pysaml2 from 7.2.1 to 7.3.1. ([\#15254](https://github.com/matrix-org/synapse/issues/15254))
- Bump msgpack from 1.0.4 to 1.0.5. ([\#15255](https://github.com/matrix-org/synapse/issues/15255))
- Bump gitpython from 3.1.30 to 3.1.31. ([\#15256](https://github.com/matrix-org/synapse/issues/15256))
- Bump cryptography from 39.0.1 to 39.0.2. ([\#15257](https://github.com/matrix-org/synapse/issues/15257))
- Skip processing of auto-join room behaviour if there are not auto-join rooms configured. ([\#15262](https://github.com/matrix-org/synapse/issues/15262))
- Remove unused store method `_set_destination_retry_timings_emulated`. ([\#15266](https://github.com/matrix-org/synapse/issues/15266))
- Clean-up direct TCP replication code. ([\#15272](https://github.com/matrix-org/synapse/issues/15272), [\#15274](https://github.com/matrix-org/synapse/issues/15274))
- Make `configure_workers_and_start` script used in Complement tests compatible with older versions of Python. ([\#15275](https://github.com/matrix-org/synapse/issues/15275))
- Bump pydantic from 1.10.4 to 1.10.6. ([\#15286](https://github.com/matrix-org/synapse/issues/15286))
- Bump serde from 1.0.155 to 1.0.157. ([\#15287](https://github.com/matrix-org/synapse/issues/15287))
- Bump anyhow from 1.0.69 to 1.0.70. ([\#15288](https://github.com/matrix-org/synapse/issues/15288))
- Bump txredisapi from 1.4.7 to 1.4.9. ([\#15289](https://github.com/matrix-org/synapse/issues/15289))
- Bump pygithub from 1.57 to 1.58.1. ([\#15290](https://github.com/matrix-org/synapse/issues/15290))
- Bump types-requests from 2.28.11.12 to 2.28.11.15. ([\#15291](https://github.com/matrix-org/synapse/issues/15291))
- Add a `/versions` flag for [MSC3952](https://github.com/matrix-org/matrix-spec-proposals/pull/3952). ([\#15293](https://github.com/matrix-org/synapse/issues/15293))
Implement [MSC3873](https://github.com/matrix-org/matrix-spec-proposals/pull/3873) to fix a long-standing bug where properties with dots were handled ambiguously in push rules.