Merge 70f6749c92 into 2a8c0bc7b8

* Part 1: Invites

* Part 2: Knocks

* Use correct schema and examples; Remind readers often about formats

* changelogs

* Add schema warning

* Name the objects

* Move changed-in and expand upon it

* Rename the example

* address review feedback

changelogs/appendices/newsfragments/2193.feature

@@ -1 +0,0 @@
-Room IDs can now appear without a domain component in [room version 12](/rooms/v12), as per [MSC4291](https://github.com/matrix-org/matrix-spec-proposals/pull/4291).

changelogs/application_service/newsfragments/2132.clarification

@@ -1 +0,0 @@
-Declare the Application Service Registration schema to follow JSON Schema spec 2020-12.

changelogs/application_service/newsfragments/2182.clarification

@@ -1 +0,0 @@
-Minor fixes to JSON schemas.

changelogs/client_server/newsfragments/2071.deprecation

@@ -1 +0,0 @@
-Deprecate `m.set_avatar_url` and `m.set_displayname` capabilities, as per [MSC4133](https://github.com/matrix-org/matrix-spec-proposals/pull/4133).

changelogs/client_server/newsfragments/2071.feature

@@ -1 +0,0 @@
-Update user profile endpoints to handle custom fields, and add a new `m.profile_fields` capability, as per [MSC4133](https://github.com/matrix-org/matrix-spec-proposals/pull/4133).

changelogs/client_server/newsfragments/2132.clarification

@@ -1 +0,0 @@
-Declare the event schemas to follow JSON Schema spec 2020-12.

changelogs/client_server/newsfragments/2167.clarification

@@ -1 +0,0 @@
-Clarify that `format` is required if `formatted_body` is specified.

changelogs/client_server/newsfragments/2169.clarification

@@ -1 +0,0 @@
-The `latest_event` in an aggregated set of thread events uses the same format as the event itself.

changelogs/client_server/newsfragments/2171.clarification

@@ -1 +0,0 @@
-Fix various typos throughout the specification.

changelogs/client_server/newsfragments/2175.feature

@@ -1 +0,0 @@
-Add `format` query parameter to `GET /state/{eventType}/{stateKey}` to allow fetching metadata of a specific state event.

changelogs/client_server/newsfragments/2177.clarification

@@ -1 +0,0 @@
-Fix various typos throughout the specification.

changelogs/client_server/newsfragments/2179.clarification

@@ -1 +0,0 @@
-Fix various typos throughout the specification.

changelogs/client_server/newsfragments/2182.clarification

@@ -1 +0,0 @@
-Minor fixes to JSON schemas.

changelogs/client_server/newsfragments/2187.feature

@@ -1 +0,0 @@
-Add the `use_state_after` query parameter and `state_after` response property to `GET /sync`, as per [MSC4222](https://github.com/matrix-org/matrix-spec-proposals/issues/4222).

changelogs/client_server/newsfragments/2193.feature.1

@@ -1 +0,0 @@
-When upgrading rooms to [room version 12](/rooms/v12), `additional_creators` may be specified on the [`POST /_matrix/client/v3/rooms/{roomId}/upgrade`](/client-server-api/#post_matrixclientv3roomsroomidupgrade) endpoint, as per [MSC4289](https://github.com/matrix-org/matrix-spec-proposals/pull/4289).

changelogs/client_server/newsfragments/2193.feature.2

@@ -1 +0,0 @@
-When creating rooms with [room version 12](/rooms/v12), the `trusted_private_chat` preset should merge the invitees into the supplied `content.additional_creators` in the resulting room, as per [MSC4289](https://github.com/matrix-org/matrix-spec-proposals/pull/4289).

changelogs/client_server/newsfragments/2193.feature.3

@@ -1 +0,0 @@
-In [room version 12](/rooms/v12), the power level of room creators is now infinitely high as per [MSC4289](https://github.com/matrix-org/matrix-spec-proposals/pull/4289).

changelogs/client_server/newsfragments/2193.feature.4

@@ -1 +0,0 @@
-In [room version 12](/rooms/v12), room IDs no longer have a domain component as per [MSC4291](https://github.com/matrix-org/matrix-spec-proposals/pull/4291).

changelogs/client_server/newsfragments/2193.feature.5

@@ -1 +0,0 @@
-When creating rooms with [room version 12](/rooms/v12), the initial power levels will restrict the ability to upgrade rooms by default, as per [MSC4289](https://github.com/matrix-org/matrix-spec-proposals/pull/4289).

changelogs/client_server/newsfragments/2195.clarification

@@ -1 +0,0 @@
-Fix `/sync` flow referencing incorrect parameter to use with `/messages`.

changelogs/client_server/newsfragments/2204.clarification

@@ -1 +0,0 @@
-Clarify wording around the `world_readable` history visibility setting. Contributed by @HarHarLinks.

changelogs/client_server/newsfragments/2206.feature

@@ -1 +0,0 @@
-Add a profile field for a user's time zone, per [MSC4175](https://github.com/matrix-org/matrix-spec-proposals/pull/4175).

changelogs/internal/newsfragments/2157.feature

@@ -1 +0,0 @@
-Add "placeholder MSC" process definition.

changelogs/internal/newsfragments/2160.clarification

@@ -1 +0,0 @@
-Upgrade the docsy theme to version 0.12.0.

changelogs/internal/newsfragments/2172.clarification

@@ -1 +0,0 @@
-GitHub actions are now building the OpenAPI `spec/identity-service-api/api.json` file.

changelogs/internal/newsfragments/2189.clarification

@@ -1 +0,0 @@
-Specify a correct spelling for "display name".

changelogs/internal/newsfragments/2190.clarification

@@ -1 +0,0 @@
-Clarify that clients should replace events with the most recent replacement by origin_server_ts.

changelogs/internal/newsfragments/2193.feature

@@ -1 +0,0 @@
-TODO: Placeholder

changelogs/internal/newsfragments/2205.clarification

@@ -1 +0,0 @@
-Fix a grammatical typo on the Matrix Spec Process documentation page.

changelogs/room_versions/newsfragments/2193.clarification

@@ -1 +0,0 @@
-In room versions 1 through 12, an event's `auth_events` have always needed to belong to the same room as per [MSC4307](https://github.com/matrix-org/matrix-spec-proposals/pull/4307).

changelogs/room_versions/newsfragments/2193.feature.1

@@ -1 +0,0 @@
-Add [room version 12](/rooms/v12) as per [MSC4304](https://github.com/matrix-org/matrix-spec-proposals/pull/4304).

changelogs/room_versions/newsfragments/2193.feature.2

@@ -1 +0,0 @@
-Room IDs in room version 12 are now the event ID of the create event with the normal room ID sigil (`!`), as per [MSC4291](https://github.com/matrix-org/matrix-spec-proposals/pull/4291).

changelogs/room_versions/newsfragments/2193.feature.3

@@ -1 +0,0 @@
-Room creators are formalized in room version 12 and have infinitely high power level, as per [MSC4289](https://github.com/matrix-org/matrix-spec-proposals/pull/4289).

changelogs/room_versions/newsfragments/2193.feature.4

@@ -1 +0,0 @@
-State Resolution is updated in room version 12 to reduce the opportunity for "state resets", as per [MSC4297](https://github.com/matrix-org/matrix-spec-proposals/pull/4297).

changelogs/room_versions/newsfragments/2193.feature.5

@@ -1 +0,0 @@
-The default room version is now room version 12, though servers SHOULD keep using room version 11 for a little while, as per [MSC4304](https://github.com/matrix-org/matrix-spec-proposals/pull/4304).

changelogs/room_versions/newsfragments/2199.feature

@@ -1 +0,0 @@
-Add [room version 12](/rooms/v12) as per [MSC4304](https://github.com/matrix-org/matrix-spec-proposals/pull/4304).

config/_default/hugo.toml

@@ -67,7 +67,7 @@ current_version_url = "https://spec.matrix.org/latest"
 # The following is used when status = "stable", and is displayed in various UI elements on a released version
 # of the spec.
 # major = "1"
-# minor = "15"
+# minor = "16"
 
 # User interface configuration
 [params.ui]

content/changelog/v1.16.md

@@ -0,0 +1,103 @@
+---
+title: v1.16 Changelog
+linkTitle: v1.16
+type: docs
+layout: changelog
+outputs:
+  - html
+  - checklist
+date: 2025-09-17
+---
+
+## Client-Server API
+
+**Deprecations**
+
+- Deprecate `m.set_avatar_url` and `m.set_displayname` capabilities, as per [MSC4133](https://github.com/matrix-org/matrix-spec-proposals/pull/4133). ([#2071](https://github.com/matrix-org/matrix-spec/issues/2071))
+
+**Removed Endpoints**
+
+- Remove unintentional intentional mentions in replies, as per [MSC4142](https://github.com/matrix-org/matrix-spec-proposals/pull/4142). ([#2210](https://github.com/matrix-org/matrix-spec/issues/2210))
+
+**Backwards Compatible Changes**
+
+- Update user profile endpoints to handle custom fields, and add a new `m.profile_fields` capability, as per [MSC4133](https://github.com/matrix-org/matrix-spec-proposals/pull/4133). ([#2071](https://github.com/matrix-org/matrix-spec/issues/2071))
+- Add `format` query parameter to `GET /state/{eventType}/{stateKey}` to allow fetching metadata of a specific state event. ([#2175](https://github.com/matrix-org/matrix-spec/issues/2175))
+- Add the `use_state_after` query parameter and `state_after` response property to `GET /sync`, as per [MSC4222](https://github.com/matrix-org/matrix-spec-proposals/issues/4222). ([#2187](https://github.com/matrix-org/matrix-spec/issues/2187))
+- When upgrading rooms to [room version 12](/rooms/v12), `additional_creators` may be specified on the [`POST /_matrix/client/v3/rooms/{roomId}/upgrade`](/client-server-api/#post_matrixclientv3roomsroomidupgrade) endpoint, as per [MSC4289](https://github.com/matrix-org/matrix-spec-proposals/pull/4289). ([#2193](https://github.com/matrix-org/matrix-spec/issues/2193))
+- When creating rooms with [room version 12](/rooms/v12), the `trusted_private_chat` preset should merge the invitees into the supplied `content.additional_creators` in the resulting room, as per [MSC4289](https://github.com/matrix-org/matrix-spec-proposals/pull/4289). ([#2193](https://github.com/matrix-org/matrix-spec/issues/2193))
+- In [room version 12](/rooms/v12), the power level of room creators is now infinitely high as per [MSC4289](https://github.com/matrix-org/matrix-spec-proposals/pull/4289). ([#2193](https://github.com/matrix-org/matrix-spec/issues/2193))
+- In [room version 12](/rooms/v12), room IDs no longer have a domain component as per [MSC4291](https://github.com/matrix-org/matrix-spec-proposals/pull/4291). ([#2193](https://github.com/matrix-org/matrix-spec/issues/2193))
+- When creating rooms with [room version 12](/rooms/v12), the initial power levels will restrict the ability to upgrade rooms by default, as per [MSC4289](https://github.com/matrix-org/matrix-spec-proposals/pull/4289). ([#2193](https://github.com/matrix-org/matrix-spec/issues/2193))
+- Add a profile field for a user's time zone, as per [MSC4175](https://github.com/matrix-org/matrix-spec-proposals/pull/4175). ([#2206](https://github.com/matrix-org/matrix-spec/issues/2206))
+- Invites and knocks are now expected to contain the `m.room.create` event in their stripped state entries, as per [MSC4311](https://github.com/matrix-org/matrix-spec-proposals/pull/4311). ([#2207](https://github.com/matrix-org/matrix-spec/issues/2207))
+
+**Spec Clarifications**
+
+- Clarify that `format` is required if `formatted_body` is specified. ([#2167](https://github.com/matrix-org/matrix-spec/issues/2167))
+- The `latest_event` in an aggregated set of thread events uses the same format as the event itself. ([#2169](https://github.com/matrix-org/matrix-spec/issues/2169))
+- Fix various typos throughout the specification. ([#2171](https://github.com/matrix-org/matrix-spec/issues/2171), [#2177](https://github.com/matrix-org/matrix-spec/issues/2177), [#2179](https://github.com/matrix-org/matrix-spec/issues/2179))
+- Clarify that clients should replace events with the most recent replacement by `origin_server_ts`. ([#2190](https://github.com/matrix-org/matrix-spec/issues/2190))
+- Fix `/sync` flow referencing incorrect parameter to use with `/messages`. ([#2195](https://github.com/matrix-org/matrix-spec/issues/2195))
+- Clarify wording around the `world_readable` history visibility setting. Contributed by @HarHarLinks. ([#2204](https://github.com/matrix-org/matrix-spec/issues/2204))
+
+
+## Server-Server API
+
+**Backwards Compatible Changes**
+
+- `invite_room_state` and `knock_room_state` now have additional requirements and validation depending on the room version, as per [MSC4311](https://github.com/matrix-org/matrix-spec-proposals/pull/4311). ([#2207](https://github.com/matrix-org/matrix-spec/issues/2207))
+
+
+## Application Service API
+
+No significant changes.
+
+
+## Identity Service API
+
+No significant changes.
+
+
+## Push Gateway API
+
+No significant changes.
+
+
+## Room Versions
+
+**Backwards Compatible Changes**
+
+- Room IDs in room version 12 are now the event ID of the create event with the normal room ID sigil (`!`), as per [MSC4291](https://github.com/matrix-org/matrix-spec-proposals/pull/4291). ([#2193](https://github.com/matrix-org/matrix-spec/issues/2193))
+- Room creators are formalized in room version 12 and have infinitely high power level, as per [MSC4289](https://github.com/matrix-org/matrix-spec-proposals/pull/4289). ([#2193](https://github.com/matrix-org/matrix-spec/issues/2193))
+- State Resolution is updated in room version 12 to reduce the opportunity for "state resets", as per [MSC4297](https://github.com/matrix-org/matrix-spec-proposals/pull/4297). ([#2193](https://github.com/matrix-org/matrix-spec/issues/2193))
+- The default room version is now room version 12, though servers SHOULD keep using room version 11 for a little while, as per [MSC4304](https://github.com/matrix-org/matrix-spec-proposals/pull/4304). ([#2193](https://github.com/matrix-org/matrix-spec/issues/2193))
+- Add [room version 12](/rooms/v12) as per [MSC4304](https://github.com/matrix-org/matrix-spec-proposals/pull/4304). ([#2193](https://github.com/matrix-org/matrix-spec/issues/2193), [#2199](https://github.com/matrix-org/matrix-spec/issues/2199))
+
+**Spec Clarifications**
+
+- In room versions 1 through 12, an event's `auth_events` have always needed to belong to the same room as per [MSC4307](https://github.com/matrix-org/matrix-spec-proposals/pull/4307). ([#2193](https://github.com/matrix-org/matrix-spec/issues/2193))
+
+
+## Appendices
+
+**Backwards Compatible Changes**
+
+- Room IDs can now appear without a domain component in [room version 12](/rooms/v12), as per [MSC4291](https://github.com/matrix-org/matrix-spec-proposals/pull/4291). ([#2193](https://github.com/matrix-org/matrix-spec/issues/2193))
+
+
+## Internal Changes/Tooling
+
+**Backwards Compatible Changes**
+
+- Add "placeholder MSC" process definition. ([#2157](https://github.com/matrix-org/matrix-spec/issues/2157))
+
+**Spec Clarifications**
+
+- Declare the Application Service Registration schema to follow JSON Schema spec 2020-12. ([#2132](https://github.com/matrix-org/matrix-spec/issues/2132))
+- Declare the event schemas to follow JSON Schema spec 2020-12. ([#2132](https://github.com/matrix-org/matrix-spec/issues/2132))
+- Upgrade the docsy theme to version 0.12.0. ([#2160](https://github.com/matrix-org/matrix-spec/issues/2160))
+- GitHub actions are now building the OpenAPI `spec/identity-service-api/api.json` file. ([#2172](https://github.com/matrix-org/matrix-spec/issues/2172))
+- Minor fixes to JSON schemas. ([#2182](https://github.com/matrix-org/matrix-spec/issues/2182))
+- Specify a correct spelling for "display name". ([#2189](https://github.com/matrix-org/matrix-spec/issues/2189))
+- Fix a grammatical typo on the Matrix Spec Process documentation page. ([#2205](https://github.com/matrix-org/matrix-spec/issues/2205))

content/client-server-api/_index.md

@@ -2818,6 +2818,14 @@ should be represented as stripped state events when possible:
 * [`m.room.canonical_alias`](#mroomcanonical_alias)
 * [`m.room.encryption`](#mroomencryption)
 
+{{% changed-in v="1.16" %}} The `m.room.create` event is now **required** in
+the following places:
+* [`invite_state`](#get_matrixclientv3sync_response-200_invited-room) and
+  [`knock_state`](#get_matrixclientv3sync_response-200_knocked-room) on
+  [`/sync`](#get_matrixclientv3sync) responses.
+* On [`m.room.member`](#mroommember) events, the `invite_room_state`
+  and `knock_room_state` under `unsigned` on the event.
+
 {{% boxes/note %}}
 Clients should inspect the list of stripped state events and not assume any
 particular event is present. The server might include events not described
@@ -2848,6 +2856,12 @@ events are not signed and could theoretically be modified, or outdated due to
 updates not being sent.
 {{% /boxes/warning %}}
 
+{{% boxes/warning %}}
+{{% added-in v="1.16" %}} Servers cannot pass through what they receive over
+federation to clients as stripped state. Servers are expected to prune the events
+into the stripped state schema below before passing the details onto clients.
+{{% /boxes/warning %}}
+
 {{% event-fields event_type="stripped_state" %}}
 
 ### Size limits

content/client-server-api/modules/rich_replies.md

@@ -64,11 +64,16 @@ as if it were to be under `m.relates_to` directly instead.
 
 #### Mentioning the replied to user
 
-In order to notify users of the reply, it may be desirable to include the `sender`
-of the replied to event and any users mentioned in that event. See
-[user and room mentions](#user-and-room-mentions) for additional information.
+{{% boxes/note %}}
+{{% changed-in v="1.16" %}}
+Clients SHOULD no longer propagate mentioned users in the replied to event.
+{{% /boxes/note %}}
 
-An example including mentioning the original sender and other users:
+In order to notify users of the reply, it MAY be desirable to include the `sender`
+of the replied to event. See [user and room mentions](#user-and-room-mentions) for
+additional information.
+
+An example including mentioning the original sender:
 
 ```json
 {
@@ -83,8 +88,6 @@ An example including mentioning the original sender and other users:
       "user_ids": [
         // The sender of $another_event.
         "@alice:example.org",
-        // Another Matrix ID copied from the m.mentions property of $another_event.
-        "@bob:example.org"
       ]
     }
   },

content/server-server-api.md

@@ -945,6 +945,18 @@ Note that invites are used to indicate that knocks were accepted. As such,
 receiving servers should be prepared to manually link up a previous knock
 to an invite if the invite event does not directly reference the knock.
 
+{{% boxes/note %}}
+{{% added-in v="1.16" %}} `invite_room_state` MUST now have its entries formatted
+according to the room's version (see [room version specification](/rooms)). However,
+servers SHOULD consider their local ecosystems before returning the described
+`400 M_MISSING_PARAM` error code. While migrating, servers SHOULD warn about
+invites which fail the validation rather than error in room versions 1 through 11.
+All invites to other room versions which fail validation SHOULD result in an error.
+
+The specification suggests that servers finish their migration no later than
+January 2026, though servers may extend this as required to support their users.
+{{% /boxes/note %}}
+
 {{% http-api spec="server-server" api="invites-v1" %}}
 
 {{% http-api spec="server-server" api="invites-v2" %}}

data/api/server-server/examples/invite_or_knock_state.json

@@ -0,0 +1,9 @@
+[
+  {"$ref": "./minimal_pdu.json"},
+  {
+    "type": "m.room.create",
+    "content": {
+      "see_room_version_spec": "The event format changes depending on the room version."
+    }
+  }
+]

data/api/server-server/invites-v1.yaml

@@ -71,13 +71,32 @@ paths:
                       properties:
                         invite_room_state:
                           type: array
+                          x-changedInMatrixVersion:
+                            "1.16": |
+                              `m.room.create` and format requirements were added.
                           description: |-
-                            An optional list of [stripped state events](/client-server-api/#stripped-state)
-                            to help the receiver of the invite identify the room.
+                            A list of state events to help the receiver of the invite identify the room.
+                            Translated as [stripped state events](/client-server-api/#stripped-state)
+                            over the Client-Server API.
+
+                            MUST contain the `m.room.create` event for the room. All events listed
+                            MUST additionally be formatted according to the room version specification.
+
+                            Servers might need to apply validation to the `invite_room_state` depending
+                            on room version. See the `400 M_MISSING_PARAM` error definition for more
+                            information.
+
+                            Note that events have a different format depending on the room
+                            version - check the [room version specification](/rooms) for
+                            precise event formats.
                           items:
-                            $ref: ../../event-schemas/schema/core-event-schema/stripped_state.yaml
-                          example:
-                            $ref: ../../event-schemas/examples/invite_room_state.json
+                            type: object
+                            title: PDU
+                            properties: {}
+                            description: |-
+                              Note that events have a different format depending on the room
+                              version - check the [room version specification](/rooms) for
+                              precise event formats.
               type: object
         required: true
       responses:
@@ -118,24 +137,7 @@ paths:
                         "origin_server_ts": 1549041175876,
                         "sender": "@someone:example.org",
                         "unsigned": {
-                          "invite_room_state": [
-                            {
-                              "type": "m.room.name",
-                              "sender": "@bob:example.org",
-                              "state_key": "",
-                              "content": {
-                                "name": "Example Room"
-                              }
-                            },
-                            {
-                              "type": "m.room.join_rules",
-                              "sender": "@bob:example.org",
-                              "state_key": "",
-                              "content": {
-                                "join_rule": "invite"
-                              }
-                            }
-                          ]
+                          "invite_room_state": {"$ref": "./examples/invite_or_knock_state.json"}
                         },
                         "content": {
                           "membership": "invite"
@@ -168,6 +170,35 @@ paths:
                     "errcode": "M_FORBIDDEN",
                     "error": "User cannot invite the target user."
                   }
+        "400":
+          description: |-
+            The `M_MISSING_PARAM` error code is used to indicate one or more of
+            the following:
+
+            * The `m.room.create` event is missing from `invite_room_state`.
+            * One or more entries in `invite_room_state` are not formatted according
+              to the room's version.
+            * One or more events fails a [signature check](/server-server-api/#validating-hashes-and-signatures-on-received-events).
+            * One or more events does not reside in the same room as the invite.
+              Note: Some room versions may require calculating the room ID for an
+              event rather than relying on the presence of `room_id`.
+
+            Servers MAY apply the validation above to room versions 1 through 11,
+            and SHOULD apply the validation above to all other room versions.
+
+            If `M_MISSING_PARAM` is returned and the request is associated with a
+            Client-Server API request, the Client-Server API request SHOULD fail
+            with a 5xx error rather than being passed through.
+          content:
+            application/json:
+              schema:
+                $ref: ../client-server/definitions/errors/error.yaml
+              examples:
+                response:
+                  value: {
+                    "errcode": "M_MISSING_PARAM",
+                    "error": "Create event not among invite state entries."
+                  }
 servers:
   - url: "{protocol}://{hostname}{basePath}"
     variables:

data/api/server-server/invites-v2.yaml

@@ -72,13 +72,32 @@ paths:
                   $ref: definitions/invite_event.yaml
                 invite_room_state:
                   type: array
+                  x-changedInMatrixVersion:
+                    "1.16": |
+                      `m.room.create` and format requirements were added.
                   description: |-
-                    An optional list of [stripped state events](/client-server-api/#stripped-state)
-                    to help the receiver of the invite identify the room.
+                    A list of state events to help the receiver of the invite identify the room.
+                    Translated as [stripped state events](/client-server-api/#stripped-state)
+                    over the Client-Server API.
+
+                    MUST contain the `m.room.create` event for the room. All events listed
+                    MUST additionally be formatted according to the room version specification.
+
+                    Servers might need to apply validation to the `invite_room_state` depending
+                    on room version. See the `400 M_MISSING_PARAM` error definition for more
+                    information.
+
+                    Note that events have a different format depending on the room
+                    version - check the [room version specification](/rooms) for
+                    precise event formats.
                   items:
-                    $ref: ../../event-schemas/schema/core-event-schema/stripped_state.yaml
-                  example:
-                    $ref: ../../event-schemas/examples/invite_room_state.json
+                    type: object
+                    title: PDU
+                    properties: {}
+                    description: |-
+                      Note that events have a different format depending on the room
+                      version - check the [room version specification](/rooms) for
+                      precise event formats.
               required:
                 - room_version
                 - event
@@ -111,24 +130,7 @@ paths:
                       "origin_server_ts": 1549041175876,
                       "sender": "@someone:example.org",
                       "unsigned": {
-                        "invite_room_state": [
-                          {
-                            "type": "m.room.name",
-                            "sender": "@bob:example.org",
-                            "state_key": "",
-                            "content": {
-                              "name": "Example Room"
-                            }
-                          },
-                          {
-                            "type": "m.room.join_rules",
-                            "sender": "@bob:example.org",
-                            "state_key": "",
-                            "content": {
-                              "join_rule": "invite"
-                            }
-                          }
-                        ]
+                        "invite_room_state": {"$ref": "./examples/invite_or_knock_state.json"}
                       },
                       "content": {
                         "membership": "invite"
@@ -151,6 +153,24 @@ paths:
 
             The error should be passed through to clients so that they
             may give better feedback to users.
+
+            The `M_MISSING_PARAM` error code is used to indicate one or more of
+            the following:
+
+            * The `m.room.create` event is missing from `invite_room_state`.
+            * One or more entries in `invite_room_state` are not formatted according
+              to the room's version.
+            * One or more events fails a [signature check](/server-server-api/#validating-hashes-and-signatures-on-received-events).
+            * One or more events does not reside in the same room as the invite.
+              Note: Some room versions may require calculating the room ID for an
+              event rather than relying on the presence of `room_id`.
+
+            Servers MAY apply the validation above to room versions 1 through 11,
+            and SHOULD apply the validation above to all other room versions.
+
+            If `M_MISSING_PARAM` is returned and the request is associated with a
+            Client-Server API request, the Client-Server API request SHOULD fail
+            with a 5xx error rather than being passed through.
           content:
             application/json:
               schema:

data/api/server-server/knocks.yaml

@@ -293,19 +293,41 @@ paths:
                   knock_room_state:
                     type: array
                     items:
-                      $ref: ../../event-schemas/schema/core-event-schema/stripped_state.yaml
+                      type: object
+                      title: PDU
+                      properties: {}
+                      description: |-
+                        Note that events have a different format depending on the room
+                        version - check the [room version specification](/rooms) for
+                        precise event formats.
+                    x-changedInMatrixVersion:
+                      "1.16": |
+                        `m.room.create` and format requirements were added.
                     description: |-
-                      A list of [stripped state events](/client-server-api/#stripped-state)
-                      to help the initiator of the knock identify the room.
+                      A list of state events to help the initiator of the knock identify
+                      the room. Translated as [stripped state events](/client-server-api/#stripped-state)
+                      over the Client-Server API.
+
+                      MUST contain the `m.room.create` event for the room. All events
+                      listed MUST additionally be formatted according to the room
+                      version specification.
+
+                      Entries which are [improperly signed](/server-server-api/#validating-hashes-and-signatures-on-received-events)
+                      or formatted SHOULD be removed by the server prior to supplying
+                      them over the Client-Server API.
+
+                      Note that events have a different format depending on the room
+                      version - check the [room version specification](/rooms) for
+                      precise event formats.
                     example:
-                      $ref: ../../event-schemas/examples/knock_room_state.json
+                      "$ref": "./examples/invite_or_knock_state.json"
                 required:
                   - knock_room_state
               examples:
                 response:
                   value: {
                     "knock_room_state": {
-                      "$ref": "../../event-schemas/examples/knock_room_state.json"
+                      "$ref": "./examples/invite_or_knock_state.json"
                     }
                   }
         "403":

data/event-schemas/schema/m.room.member.yaml

@@ -137,6 +137,9 @@ properties:
       - type: object
         properties:
           invite_room_state:
+            x-changedInMatrixVersion:
+              "1.16": |
+                `m.room.create` was made a required event type for stripped state.
             description: |-
               A subset of the state of the room at the time of the invite, if `membership` is `invite`.
               Note that this state is informational, and SHOULD NOT be trusted; once the client has
@@ -145,16 +148,21 @@ properties:
               they SHOULD behave properly (with possibly a degraded but not a broken experience) in
               the absence of any particular events here. If they are set on the room, at least the
               state for `m.room.avatar`, `m.room.canonical_alias`, `m.room.join_rules`, and `m.room.name`
-              SHOULD be included.
+              SHOULD be included. The `m.room.create` event MUST be included, though MAY be missing if
+              the server hasn't updated to support the Matrix 1.16 specification.
             items:
               $ref: "core-event-schema/stripped_state.yaml"
             type: array
           knock_room_state:
+            x-changedInMatrixVersion:
+              "1.16": |
+                `m.room.create` was made a required event type for stripped state.
             description: |-
               A subset of the state of the room at the time of the knock, if `membership` is `knock`.
               This has the same restrictions as `invite_room_state`. If they are set on the room, at least
               the state for `m.room.avatar`, `m.room.canonical_alias`, `m.room.join_rules`, `m.room.name`,
-              and `m.room.encryption` SHOULD be included.
+              and `m.room.encryption` SHOULD be included. The `m.room.create` event MUST be included,
+              though MAY be missing if the server hasn't updated to support the Matrix 1.16 specification.
             items:
               $ref: "core-event-schema/stripped_state.yaml"
             type: array