This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [element-hq/synapse](https://github.com/element-hq/synapse) | minor | `1.145.0` → `1.146.0` |

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### Release Notes

<details>
<summary>element-hq/synapse (element-hq/synapse)</summary>

### [`v1.146.0`](https://github.com/element-hq/synapse/releases/tag/v1.146.0)

[Compare Source](element-hq/synapse@v1.145.0...v1.146.0rc1)

### Synapse 1.146.0 (2026-01-27)

No significant changes since 1.146.0rc1.

#### Deprecations and Removals

- [MSC2697](matrix-org/matrix-spec-proposals#2697) (Dehydrated devices) has been removed, as the MSC is closed. Developers should migrate to [MSC3814](matrix-org/matrix-spec-proposals#3814). ([#&#8203;19346](element-hq/synapse#19346))
- Support for Ubuntu 25.04 (Plucky Puffin) has been dropped. Synapse no longer builds debian packages for Ubuntu 25.04.

### Synapse 1.146.0rc1 (2026-01-20)

#### Features

- Add a new config option [`enable_local_media_storage`](https://element-hq.github.io/synapse/latest/usage/configuration/config_documentation.html#enable_local_media_storage) which controls whether media is additionally stored locally when using configured `media_storage_providers`. Setting this to `false` allows off-site media storage without a local cache. Contributed by Patrice Brend'amour [@&#8203;dr](https://github.com/dr).allgood. ([#&#8203;19204](element-hq/synapse#19204))
- Stabilise support for [MSC4312](matrix-org/matrix-spec-proposals#4312 `m.oauth` User-Interactive Auth stage for resetting cross-signing identity with the OAuth 2.0 API. The old, unstable name (`org.matrix.cross_signing_reset`) is now deprecated and will be removed in a future release. ([#&#8203;19273](element-hq/synapse#19273))
- Refactor Grafana dashboard to use `server_name` label (instead of `instance`). ([#&#8203;19337](element-hq/synapse#19337))

#### Bugfixes

- Fix joining a restricted v12 room locally when no local room creator is present but local users with sufficient power levels are. Contributed by [@&#8203;nexy7574](https://github.com/nexy7574). ([#&#8203;19321](element-hq/synapse#19321))
- Fixed parallel calls to `/_matrix/media/v1/create` being ratelimited for appservices even if `rate_limited: false` was set in the registration. Contributed by [@&#8203;tulir](https://github.com/tulir) @&#8203; Beeper. ([#&#8203;19335](element-hq/synapse#19335))
- Fix a bug introduced in 1.61.0 where a user's membership in a room was accidentally ignored when considering access to historical state events in rooms with the "shared" history visibility. Contributed by Lukas Tautz. ([#&#8203;19353](element-hq/synapse#19353))
- [MSC4140](matrix-org/matrix-spec-proposals#4140): Store the JSON content of scheduled delayed events as text instead of a byte array. This fixes the inability to schedule a delayed event with non-ASCII characters in its content. ([#&#8203;19360](element-hq/synapse#19360))
- Always rollback database transactions when retrying (avoid orphaned connections). ([#&#8203;19372](element-hq/synapse#19372))
- Fix `InFlightGauge` typing to allow upgrading to `prometheus_client` 0.24. ([#&#8203;19379](element-hq/synapse#19379))

#### Updates to the Docker image

- Add [Prometheus HTTP service discovery](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#http_sd_config) endpoint for easy discovery of all workers when using the `docker/Dockerfile-workers` image (see the [*Metrics* section of our Docker testing docs](docker/README-testing.md#metrics)). ([#&#8203;19336](element-hq/synapse#19336))

#### Improved Documentation

- Remove docs on legacy metric names (no longer in the codebase since 2022-12-06). ([#&#8203;19341](element-hq/synapse#19341))
- Clarify how the estimated value of room complexity is calculated internally. ([#&#8203;19384](element-hq/synapse#19384))

#### Internal Changes

- Add an internal `cancel_task` API to the task scheduler. ([#&#8203;19310](element-hq/synapse#19310))
- Tweak docstrings and signatures of `auth_types_for_event` and `get_catchup_room_event_ids`. ([#&#8203;19320](element-hq/synapse#19320))
- Replace usage of deprecated `assertEquals` with `assertEqual` in unit test code. ([#&#8203;19345](element-hq/synapse#19345))
- Drop support for Ubuntu 25.04 'Plucky Puffin', add support for Ubuntu 25.10 'Questing Quokka'. ([#&#8203;19348](element-hq/synapse#19348))
- Revert "Add an Admin API endpoint for listing quarantined media ([#&#8203;19268](element-hq/synapse#19268))". ([#&#8203;19351](element-hq/synapse#19351))
- Bump `mdbook` from 0.4.17 to 0.5.2 and remove our custom table-of-contents plugin in favour of the new default functionality. ([#&#8203;19356](element-hq/synapse#19356))
- Replace deprecated usage of PyGitHub's `GitRelease.title` with `.name` in release script. ([#&#8203;19358](element-hq/synapse#19358))
- Update the Element logo in Synapse's README to be an absolute URL, allowing it to render on other sites (such as PyPI). ([#&#8203;19368](element-hq/synapse#19368))
- Apply minor tweaks to v1.145.0 changelog. ([#&#8203;19376](element-hq/synapse#19376))
- Update Grafana dashboard syntax to use the latest from importing/exporting with Grafana 12.3.1. ([#&#8203;19381](element-hq/synapse#19381))
- Warn about skipping reactor metrics when using unknown reactor type. ([#&#8203;19383](element-hq/synapse#19383))
- Add support for reactor metrics with the `ProxiedReactor` used in worker Complement tests. ([#&#8203;19385](element-hq/synapse#19385))

</details>

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support for [MSC4140](matrix-org/matrix-spec-proposals#4140) scheduled messages