Merge 282a44f5c5 into 935c23485b

Changelog

changelogs/client_server/newsfragments/2232.clarification

@@ -0,0 +1 @@
+M_RESOURCE_LIMIT_EXCEEDED is now listed as a common error code.

changelogs/client_server/newsfragments/2240.clarification

@@ -0,0 +1 @@
+Clarify how to use `state_after` ahead of declaring full support for its spec version.

content/client-server-api/_index.md

@@ -136,6 +136,17 @@ code if the endpoint is implemented, but the incorrect HTTP method is used.
 {{% added-in v="1.17" %}} The device ID supplied by the application service does
 not belong to the user ID during [identity assertion](/application-service-api/#identity-assertion).
 
+`M_RESOURCE_LIMIT_EXCEEDED`
+The request cannot be completed because the homeserver has reached a
+resource limit imposed on it. For example, a homeserver held in a shared
+hosting environment may reach a resource limit if it starts using too
+much memory or disk space. The error MUST have an `admin_contact` field
+to provide the user receiving the error a place to reach out to.
+Typically, this error will appear on routes which attempt to modify
+state (e.g.: sending messages, account data, etc) and not routes which
+only read state (e.g.: [`/sync`](#get_matrixclientv3sync),
+[`/user/{userId}/account_data/{type}`](#get_matrixclientv3useruseridaccount_datatype), etc).
+
 `M_UNKNOWN`
 An unknown error has occurred.
 
@@ -221,17 +232,6 @@ The request or entity was too large.
 The resource being requested is reserved by an application service, or
 the application service making the request has not created the resource.
 
-`M_RESOURCE_LIMIT_EXCEEDED`
-The request cannot be completed because the homeserver has reached a
-resource limit imposed on it. For example, a homeserver held in a shared
-hosting environment may reach a resource limit if it starts using too
-much memory or disk space. The error MUST have an `admin_contact` field
-to provide the user receiving the error a place to reach out to.
-Typically, this error will appear on routes which attempt to modify
-state (e.g.: sending messages, account data, etc) and not routes which
-only read state (e.g.: [`/sync`](#get_matrixclientv3sync),
-[`/user/{userId}/account_data/{type}`](#get_matrixclientv3useruseridaccount_datatype), etc).
-
 `M_CANNOT_LEAVE_SERVER_NOTICE_ROOM`
 The user is unable to reject an invite to join the server notices room.
 See the [Server Notices](#server-notices) module for more information.

data/api/client-server/sync.yaml

@@ -133,10 +133,15 @@ paths:
             sync and the **start** of the timeline in `state` and MUST omit
             `state_after`.
 
-            Even if this is set to `true`, clients MUST update their local state
-            with events in `state` and `timeline` if `state_after` is missing in
-            the response, for compatibility with servers that don't support this
-            parameter.
+            Servers MAY implement this parameter ahead of declaring support for
+            the version of the spec in which it was introduced. Consequently,
+            clients MAY set this parameter to `true` regardless of the
+            [`/versions`](/client-server-api/#get_matrixclientversions) response.
+            If they do, they can infer whether the server actually supports this
+            parameter from the presence of `state_after` in the response. If
+            `state_after` is missing, clients MUST behave as if they had not
+            specified the parameter and update their local state with events
+            in `state` and `timeline`.
 
             By default, this is `false`.
           example: false