MSC4452: Preview URL capability by Half-Shot · Pull Request #19715 · element-hq/synapse

Half-Shot · 2026-04-21T16:26:16Z

Implementation of matrix-org/matrix-spec-proposals#4452

1vel

We will also need to return a 403/M_FORBIDDEN, which requires always registering the servlet in synapse/rest/client/media.py.

Half-Shot · 2026-04-21T17:37:04Z

We will also need to return a 403/M_FORBIDDEN, which requires always registering the servlet in synapse/rest/client/media.py.

Yep, got distracted 🫠 . Will do.

reivilibre

Seems broadly fine, appears to match the MSC, LGTM otherwise

reivilibre

LGTM otherwise

reivilibre · 2026-05-11T10:17:40Z

            access_token=self.tok,
        )
-        self.assertEqual(channel.code, 404, channel.result)
+        self.assertEqual(channel.code, 400, channel.result)


I think this changing to 400 is undesirable

M_UNRECOGNIZED
The server did not understand the request. This is expected to be returned with a 404 HTTP status code if the endpoint is not implemented or a 405 HTTP status code if the endpoint is implemented, but the incorrect HTTP method is used.
— https://spec.matrix.org/v1.18/client-server-api/

I think the 400 was an old-spec thing. Might need to set the status code onn UnrecognizedRequestError

…orkers when MSC4452: Preview URL capabilities API is enabled. (#19839) Fixes: #19825 Introduced in: #19715 Always populate `url_preview_enabled` so `/capabilities` can expose it Needed so this line can be happy: https://github.com/element-hq/synapse/blob/106ed3623d434891fe1ac50aacc851e9804404fe/synapse/rest/client/capabilities.py#L82 --------- Signed-off-by: Olivier 'reivilibre <oliverw@matrix.org>

Implementation of matrix-org/matrix-spec-proposals#4452

@jason-famedly

Tested on NetBSD 10 amd64 with 2026Q2 environment. # Synapse 1.156.0 (2026-07-07) ## Features - Expose [MSC4354 Sticky Events](matrix-org/matrix-spec-proposals#4354) over [MSC4186 (Simplified) Sliding Sync](matrix-org/matrix-spec-proposals#4186). ([\#19591](element-hq/synapse#19591)) - Stabilize support for sending ephemeral events to application services, as per [MSC2409](matrix-org/matrix-spec-proposals#2409). Contributed by @jason-famedly @ Famedly. ([\#19758](element-hq/synapse#19758)) - Include `allowed_room_ids` in the `/summary` client-server API response for rooms with restricted join rules, as required by Matrix 1.15. Contributed by @FrenchGithubUser @famedly. ([\#19762](element-hq/synapse#19762)) - [MSC4140: Cancellable delayed events](matrix-org/matrix-spec-proposals#4140): Allow authentication on delayed event management endpoints (such as `/restart`) to bypass ratelimits for unauthenticated requests based on the client IP address. ([\#19794](element-hq/synapse#19794)) - Add new metric `synapse_non_deactivated_user_count` which tracks the number of non-deactivated users in the database, split by `app_service`. ([\#19848](element-hq/synapse#19848)) - The `GET /_matrix/client/unstable/org.matrix.msc1763/retention/configuration` endpoint is now provided when retention is enabled and `experimental_features.msc1763_enabled` is enabled, based on [MSC1763](matrix-org/matrix-spec-proposals#1763). ([\#19853](element-hq/synapse#19853)) - Add experimental support for [MSC4491: Invite reasons in room creation](matrix-org/matrix-spec-proposals#4491). ([\#19874](element-hq/synapse#19874)) # Synapse 1.155.0 (2026-06-16) # Synapse 1.154.0 (2026-06-04) ## Features - Add support for [MSC4452: Preview URL capabilities API](matrix-org/matrix-spec-proposals#4452) which exposes a `io.element.msc4452.preview_url` capability. If `experimental_features.msc4452_enabled` is `true`, the `/_matrix/(client/v1/media|media/v3)/preview_url` endpoint now responds with a 403 status code when the capability is disabled. ([\#19715](element-hq/synapse#19715)) # Synapse 1.153.0 (2026-05-19) ## Features - Make ACLs apply to EDUs per [MSC4163](matrix-org/matrix-spec-proposals#4163). ([\#18475](element-hq/synapse#18475)) - Stabilize [MSC3266: Room summary API](matrix-org/matrix-spec-proposals#3266), removing the experimental config flag `msc3266_enabled`. Contributed by @dasha-uwu. ([\#19720](element-hq/synapse#19720)) - Partial [MSC4311](matrix-org/matrix-spec-proposals#4311) implementation: `m.room.create` is now a required part of stripped `invite_state`/`knock_state` . Contributed by @FrenchGithubUser @famedly. ([\#19722](element-hq/synapse#19722)) - Expose `tombstoned` and `replacement_room` in room details on admin API endpoint `GET /_synapse/admin/v1/rooms/<room_id>`. Contributed by Noah Markert. ([\#19737](element-hq/synapse#19737)) # Synapse 1.152.1 (2026-05-07) # Synapse 1.152.0 (2026-04-28) ## Features - 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](element-hq/synapse#19558), [\#19677](element-hq/synapse#19677), [\#19694](element-hq/synapse#19694)) - Advertise [MSC4445](matrix-org/matrix-spec-proposals#4445) sync timeline order in `unstable_features`. ([\#19642](element-hq/synapse#19642)) - Report the Rust compiler version used in the Prometheus metrics. Contributed by Noah Markert. ([\#19643](element-hq/synapse#19643)) - Passthrough 'article' and 'profile' OpenGraph metadata on URL preview requests. ([\#19659](element-hq/synapse#19659)) - Add a way to re-sign local events with a new signing key. ([\#19668](element-hq/synapse#19668)) - Support [MSC4450: Identity Provider selection for User-Interactive Authentication with Legacy Single Sign-On](matrix-org/matrix-spec-proposals#4450). ([\#19693](element-hq/synapse#19693)) - Add experimental support for [MSC4242](matrix-org/matrix-spec-proposals#4242): State DAGs. Excludes federation support. ([\#19424](element-hq/synapse#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](element-hq/synapse#19657)) - Reduce database disk space usage by pruning old rows from `device_lists_changes_in_room`. ([\#19473](element-hq/synapse#19473), [\#19709](element-hq/synapse#19709)) # Synapse 1.151.0 (2026-04-07) ## Features - Add stable support for [MSC4284](matrix-org/matrix-spec-proposals#4284) Policy Servers. ([\#19503](element-hq/synapse#19503)) - Update and stabilize support for [MSC2666](matrix-org/matrix-spec-proposals#2666): Get rooms in common with another user. Contributed by @tulir @ Beeper. ([\#19511](element-hq/synapse#19511)) - Updated experimental support for [MSC4388: Secure out-of-band channel for sign in with QR](matrix-org/matrix-spec-proposals#4388). ([\#19573](element-hq/synapse#19573)) - Stabilize `room_version` and `encryption` fields in the space/room `/hierarchy` API (part of [MSC3266](matrix-org/matrix-spec-proposals#3266)). ([\#19576](element-hq/synapse#19576)) - Introduce a [configuration option](https://element-hq.github.io/synapse/latest/usage/configuration/config_documentation.html#matrix_authentication_service) to allow using HTTP/2 over plaintext when Synapse connects to Matrix Authentication Service. ([\#19586](element-hq/synapse#19586)) ## Deprecations and Removals - Remove support for [MSC3852: Expose user agent information on Device](matrix-org/matrix-spec-proposals#3852) as the MSC was closed. ([\#19430](element-hq/synapse#19430)) # Synapse 1.150.0 (2026-03-24) ## Features - Add experimental support for the [MSC4370](matrix-org/matrix-spec-proposals#4370) Federation API `GET /extremities` endpoint. ([\#19314](element-hq/synapse#19314)) - [MSC4140: Cancellable delayed events](matrix-org/matrix-spec-proposals#4140): When persisting a delayed event to the timeline, include its `delay_id` in the event's `unsigned` section in `/sync` responses to the event sender. ([\#19479](element-hq/synapse#19479)) - Expose [MSC4354 Sticky Events](matrix-org/matrix-spec-proposals#4354) over the legacy (v3) /sync API. ([\#19487](element-hq/synapse#19487)) - When Matrix Authentication Service (MAS) integration is enabled, allow MAS to set the user locked status in Synapse. ([\#19554](element-hq/synapse#19554))

Add capability

7285553

Half-Shot requested a review from a team as a code owner April 21, 2026 16:26

fixup

fff9810

1vel suggested changes Apr 21, 2026

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Comment thread tests/rest/client/test_capabilities.py

Give proper error when disabling endpoint and add tests.

5c6188a

Half-Shot mentioned this pull request Apr 21, 2026

MSC4452: Preview URL capabilities API matrix-org/matrix-spec-proposals#4452

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1vel reviewed Apr 21, 2026

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Comment thread tests/rest/client/test_media.py Outdated

1vel reviewed Apr 21, 2026

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Comment thread tests/rest/client/test_media.py

MadLittleMods added the A-URL-Preview label Apr 21, 2026

Half-Shot added 2 commits April 22, 2026 10:09

Check auth first (so as not to leak configuration)

797a2eb

Request with an access token

074a465

Half-Shot commented Apr 22, 2026

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Comment thread synapse/rest/client/capabilities.py Outdated

Half-Shot commented Apr 22, 2026

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Comment thread synapse/rest/media/preview_url_resource.py Outdated

Half-Shot added 3 commits April 22, 2026 14:19

ensure disabled

1b84344

Cleanup

24baa89

Update to use an experimental_feature

484e780

Half-Shot mentioned this pull request Apr 23, 2026

MSC4452: Preview URL capability #19719

Open

Replace missing return

c96abf9

reivilibre requested changes Apr 28, 2026

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Comment thread synapse/rest/media/preview_url_resource.py Outdated

Comment thread synapse/config/repository.py Outdated

Comment thread synapse/rest/client/media.py Outdated

Half-Shot added 3 commits April 28, 2026 16:01

Fix disabled case

eecaf22

cleanup config

1f42358

remove out of date comment

25f49fb

Half-Shot requested a review from reivilibre April 28, 2026 15:05

fix test

5c96961

reivilibre approved these changes May 11, 2026

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fix based on review comments

d587acf

reivilibre merged commit 5c87faf into develop May 11, 2026
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reivilibre deleted the hs/4452-url-preview-caps branch May 11, 2026 11:39

Half-Shot mentioned this pull request May 11, 2026

Add msc4452_enabled to experimental_features. element-hq/ess-helm#1290

Merged

reivilibre mentioned this pull request Jun 9, 2026

Fix the /capabilities endpoint returning a 500 error on non-media workers when MSC4452: Preview URL capabilities API is enabled. #19839

Merged

FrenchGithubUser pushed a commit to famedly/synapse-upstreaming that referenced this pull request Jun 12, 2026

MSC4452: Preview URL capability (element-hq#19715)

8be67f2

Implementation of matrix-org/matrix-spec-proposals#4452

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MSC4452: Preview URL capability - #19715

MSC4452: Preview URL capability#19715
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