MSC Support

MSCs (Matrix Spec Changes) are proposals to extend or modify the Matrix protocol. This page tracks the implementation status of notable MSCs in Zendrite.

Many MSCs listed here have since been merged into the Matrix specification proper. They are listed by their original MSC number and the first spec version which includes them.

Sync

MSC	Title	Spec	Status
MSC4186	Simplified Sliding Sync	N/A	Implemented (native, no proxy needed)
MSC3575	Sliding Sync (v1)	N/A	Implemented (legacy, superseded by MSC4186)

Messaging

MSC	Title	Spec	Status
MSC2675	Serverside aggregations of message relationships	1.3	Implemented
MSC2676	Message editing	1.4	Implemented
MSC2677	Reactions	1.7	Implemented
MSC2836	Threading	N/A	Opt-in (msc2836)
MSC2285	Private read receipts	1.4	Implemented

Rooms & Spaces

MSC	Title	Spec	Status
MSC1772	Spaces	1.2	Implemented
MSC2946	Spaces summary / room hierarchy	1.2	Implemented
MSC3083	Restricted rooms (space-based membership)	1.2	Implemented
MSC2403	Knocking	1.1	Implemented
MSC3266	Room summary API	1.15	Implemented
MSC3765	Rich text in room topics	1.15	Not implemented

Encryption & Security

MSC	Title	Spec	Status
MSC3916	Authenticated media	1.11	Implemented
MSC2732	OLM fallback keys	1.2	Implemented
MSC3814	Dehydrated devices v2	N/A	Opt-in (msc3814)
MSC4115	Membership metadata on events	1.11	Opt-in (msc4115)

Federation

MSC	Title	Spec	Status
MSC3706	Partial state in /send_join (faster joins)	1.6	Implemented
MSC2444	Peeking over federation	N/A	Opt-in (msc2444)
MSC2753	Peeking via /sync	N/A	Opt-in (msc2753)

Authentication

MSC	Title	Spec	Status
MSC2918	Refresh tokens	1.3	Implemented
MSC3861	Next-gen auth (OIDC)	1.15	Opt-in (msc3861)

VoIP

MSC	Title	Spec	Status
MSC4143	MatrixRTC transport discovery	N/A	Implemented

Opt-in MSCs

The following MSCs are not enabled by default and must be activated in the mscs section of the config file:

mscs:
  mscs:
    - msc2836
    - msc2444
    - msc2753
    - msc3814
    - msc3861
    - msc4115

MSC3814: Dehydrated Devices v2

MSC3814 allows clients to store a “dehydrated” device on the server so that encrypted to-device messages (e.g. key shares) can be delivered while the user is offline. When the user signs in again, the client rehydrates the device and retrieves messages it missed.

What changes when MSC3814 is enabled:

• PUT /_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device — store a dehydrated device with its keys.
• GET /_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device — retrieve the current dehydrated device metadata.
• DELETE /_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device — remove the dehydrated device.
• POST /_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device/{deviceID}/events — retrieve to-device events addressed to the dehydrated device.

Configuration:

mscs:
  mscs:
    - msc3814

No additional configuration is needed beyond enabling the MSC.

MSC3861: OIDC Delegated Authentication

MSC3861 delegates authentication to an external OpenID Connect (OIDC) provider such as Matrix Authentication Service (MAS). When enabled, Zendrite validates access tokens via OAuth 2.0 token introspection instead of managing passwords directly.

What changes when MSC3861 is enabled:

• Password-based registration and login are disabled.
• GET /login returns only the m.login.sso flow.
• POST /login, /register, /account/password, /account/deactivate, /logout, /logout/all, /delete_devices, and device modification endpoints return 403 M_FORBIDDEN.
• /.well-known/matrix/client includes an m.authentication section with the OIDC issuer.
• New users are auto-provisioned on first token introspection.

Configuration:

mscs:
  mscs:
    - msc3861
  msc3861:
    issuer: "https://auth.example.com/"
    client_id: "0000000000000000000ZENDRITE"
    client_secret: "secret"
    client_auth_method: "client_secret_basic"  # or "client_secret_post"
    admin_token: ""                            # optional: static token for admin API access
    account_management_url: ""                 # optional: URL for account management UI
    introspection_endpoint: ""                 # optional: defaults to {issuer}/oauth2/introspect

Field	Required	Description
issuer	Yes	The OIDC provider URL (e.g. your MAS instance).
client_id	Yes	OAuth 2.0 client ID registered with the OIDC provider for introspection.
client_secret	Yes	OAuth 2.0 client secret for introspection.
client_auth_method	No	Authentication method: client_secret_basic (default) or client_secret_post.
admin_token	No	A static bearer token that grants admin access, bypassing OIDC introspection. Useful for service-to-service calls.
account_management_url	No	URL where users can manage their account (shown in well-known response).
introspection_endpoint	No	Override the introspection endpoint URL. Defaults to {issuer}/oauth2/introspect.