For deployments using workers, please note that this version introduces a new `quarantined_media_changes` stream writer, which may require configuration changes. Please see the [the relevant section in the upgrade notes](https://github.com/element-hq/synapse/blob/develop/docs/upgrade.md#upgrading-to-v11520) for details. Without configuring this new stream writer, only the main process will be able to handle the `/media/quarantine` admin API endpoints for quarantining media. - Add a ["Listing quarantined media changes" Admin API](https://element-hq.github.io/synapse/latest/admin_api/media_admin_api.html#listing-quarantined-media-changes) for retrieving a paginated record of when media became (un)quarantined. ([\#19558](https://github.com/element-hq/synapse/issues/19558), [\#19677](https://github.com/element-hq/synapse/issues/19677)) - Advertise [MSC4445](https://github.com/matrix-org/matrix-spec-proposals/pull/4445) sync timeline order in `unstable_features`. ([\#19642](https://github.com/element-hq/synapse/issues/19642)) - Report the Rust compiler version used in the Prometheus metrics. Contributed by Noah Markert. ([\#19643](https://github.com/element-hq/synapse/issues/19643)) - Passthrough 'article' and 'profile' OpenGraph metadata on URL preview requests. ([\#19659](https://github.com/element-hq/synapse/issues/19659)) - Add a way to re-sign local events with a new signing key. ([\#19668](https://github.com/element-hq/synapse/issues/19668)) - Support [MSC4450: Identity Provider selection for User-Interactive Authentication with Legacy Single Sign-On](https://github.com/matrix-org/matrix-spec-proposals/pull/4450). ([\#19693](https://github.com/element-hq/synapse/issues/19693)) - Add a ["Listing quarantined media changes" Admin API](https://element-hq.github.io/synapse/latest/admin_api/media_admin_api.html#listing-quarantined-media-changes) for retrieving a paginated record of when media became (un)quarantined. ([\#19694](https://github.com/element-hq/synapse/issues/19694)) - Add experimental support for [MSC4242](https://github.com/matrix-org/matrix-spec-proposals/pull/4242): State DAGs. Excludes federation support. ([\#19424](https://github.com/element-hq/synapse/issues/19424)) - Adds [Admin API](https://element-hq.github.io/synapse/latest/usage/administration/admin_api/index.html) endpoints to list, fetch and delete user reports. ([\#19657](https://github.com/element-hq/synapse/issues/19657)) - Reduce database disk space usage by pruning old rows from `device_lists_changes_in_room`. ([\#19473](https://github.com/element-hq/synapse/issues/19473), [\#19709](https://github.com/element-hq/synapse/issues/19709)) - Reject `device_keys: null` in the request to [`POST /_matrix/client/v3/keys/upload`](https://spec.matrix.org/v1.16/client-server-api/#post_matrixclientv3keysupload), as per the spec. This was temporarily allowed as a workaround for misbehaving clients. ([\#19637](https://github.com/element-hq/synapse/issues/19637)) - Fix database migrations failing on platforms where SQLite is configured with `SQLITE_DBCONFIG_DEFENSIVE` by default, such as macOS. ([\#19690](https://github.com/element-hq/synapse/issues/19690)) - Fix a bug introduced in v1.145 where a non-admin could bypass admin checks for downloading remote quarantined media. This relied on the media already being previously present on the homeserver. ([\#19639](https://github.com/element-hq/synapse/issues/19639)) - Include a workaround for running the unit tests with SQLite under recent versions of MacOS. ([\#19615](https://github.com/element-hq/synapse/issues/19615)) - Fix Docker image link typo in worker docs. ([\#19645](https://github.com/element-hq/synapse/issues/19645)) - Update developer stream docs for creating a new stream to point out `_setup_sequence(...)` in `portdb`. ([\#19675](https://github.com/element-hq/synapse/issues/19675)) - Update the developer stream docs for creating a new stream to highlight places that require documentation updates. ([\#19696](https://github.com/element-hq/synapse/issues/19696)) - Update CI to use re-usable Complement GitHub CI workflow. ([\#19533](https://github.com/element-hq/synapse/issues/19533)) - Fix docstring for `limit` argument in `_maybe_backfill_inner(...)`. ([\#19630](https://github.com/element-hq/synapse/issues/19630)) - Document context for why increase timeout for policy server requests. ([\#19633](https://github.com/element-hq/synapse/issues/19633)) - Run lint script to format Complement tests introduced in [#19509](https://github.com/element-hq/synapse/pull/19509). ([\#19636](https://github.com/element-hq/synapse/issues/19636)) - Small simplifications to the events class. ([\#19680](https://github.com/element-hq/synapse/issues/19680), [\#19712](https://github.com/element-hq/synapse/issues/19712)) - Introduce `spam_checker_spammy` internal event metadata. ([\#19453](https://github.com/element-hq/synapse/issues/19453)) - Add a `FilteredEvent` class that saves us copying events. ([\#19640](https://github.com/element-hq/synapse/issues/19640)) - Convert `EventInternalMetadata` to use `Arc<RwLock<_>>`. ([\#19669](https://github.com/element-hq/synapse/issues/19669))