Support Matrix 1.19

[turt2live]

Following #19932

Matrix Specification v1.19 Changelog

Git commit	https://github.com/matrix-org/matrix-spec/tree/v1.19
Release date	July 8, 2026

Client-Server API

New Endpoints

• Add GET /_matrix/client/v1/mutual_rooms, as per MSC2666. (#2367)

Backwards Compatible Changes

• Specify unsigned.replaces_state in client-formatted events. Contributed by @nexy7574. (#2345, #2403)
• Specify m.key_backup account data, as per MSC4287. (#2354)
• The room directory now returns rooms in a server-defined order rather than largest first, as per MSC4423. (#2392)
• Add support for image packs (m.room.image_pack and m.image_pack.rooms), allowing custom emoticons and stickers to be organised into packs and shared between users, as per MSC2545. (#2397)
• Specify encrypted history sharing, as per MSC4268. (#2399)

Spec Clarifications

• Clarify SAS commitment calculation for m.key.verification.accept messages. (#2344)
• Clarify formats of string types. (#2347, #2349, #2358, #2359, #2370, #2374, #2375, #2376)
• Restore alphabetical order of common error codes. (#2348)
• Fix various typos throughout the specification. (#2351, #2389)
• Clarify how to find via parameter when following room upgrades. (#2352)
• Clarify that room messages can be encrypted. (#2371)
• Clarify how to paginate messages using the pagination tokens returned by GET /rooms/{roomId}/context/{eventId}. (#2372)
• Clarify allowed characters in mxc:// URIs. (#2377)
• Add link to RFC 9700 OAuth 2.0 Best Current Practices. (#2379)
• Add links from the Client-Server spec to the Olm message definitions. (#2381)
• Disambiguate placeholder descriptions in OlmPayload example. (#2382)
• Replace "Olm message" with "event encrypted using Olm" where not referring to the Olm message format. (#2383)
• Removed unused components in OpenAPI definitions. (#2386)
• Clarify definitions of EncryptedFile structure. (#2398)

Server-Server API

Backwards Compatible Changes

• The room directory now returns rooms in a server-defined order rather than largest first, as per MSC4423. (#2392)

Spec Clarifications

• Clarify the behaviour and response format of GET /_matrix/federation/v1/query/profile. (#2326)
• Clarify that server ACLs are case-insensitive, as per MSC4436. (#2334)
• Clarify how multiple signatures should be handled during signature verification. Contributed by @nexy7574. (#2341)
• Fix various typos throughout the specification. (#2351)
• Clarify that policy servers might share a name with event origins, and that servers should avoid overwriting/discarding signatures for the event origin when getting a policy server signature. (#2385)

Application Service API

Spec Clarifications

• Fix various typos throughout the specification. (#2351)

Identity Service API

Spec Clarifications

• Fix various typos throughout the specification. (#2401)

Push Gateway API

No significant changes.

Room Versions

Spec Clarifications

• Fix various typos throughout the specification. (#2351, #2401)

Olm & Megolm

Spec Clarifications

• Update links to Olm in the Megolm section to point to the Matrix spec. (#2361)
• Fix various typos throughout the specification. (#2369)
• Update link from whispersystems.org to signal.org in the olm documentation. (#2387)

Appendices

Spec Clarifications

• Update the canonical JSON grammar with case sensitive strings and ABNF builtins to be easier to understand. (#2368)
• Fix various typos throughout the specification. (#2369)
• Clarify matrix.to RFC 3986 percent encoding requirements. Contributed by @HarHarLinks. (#2395)
• Add specification of URL-safe unpadded Base64. (#2398)

Internal Changes/Tooling

Backwards Compatible Changes

• Add page search widget. (#2331)

Spec Clarifications

• Update and fix GitHub Actions. (#2343, #2369)
• Upgrade Docsy theme to v0.14.3. (#2346)
• Configure a new changelog section for the Olm & Megolm specs. (#2364)
• Clarify use of UK vs US English in documentation style doc. (#2366)
• Ignore typos in copyright statements. (#2373)
• Update CODEOWNERS file. (#2400)
• Minor fixes to check-newsfragments CI script. (#2402)