Merge 4842d9e9aa into 8ebf4a4789

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

changelogs/client_server/newsfragments/2245.clarification

@@ -0,0 +1 @@
+`device_one_time_keys_count` is only optional if no unclaimed one-time keys exist.

changelogs/room_versions/newsfragments/2249.clarification

@@ -0,0 +1 @@
+In room versions 3 through 12, clarify that when you have the power to redact, it is possible to redact events that you don't have the power to send.  

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

@@ -1775,17 +1775,16 @@ property is required for inclusion, though previous versions of the
 specification did not have it. In addition to `/versions`, this can be
 a way to identify the server's support for fallback keys.
 
-
 | Parameter                        | Type              | Description                                                                                                            |
-|----------------------------------|--------------------|------------------------------------------------------------------------------------------------------------------------|
+|----------------------------------|-------------------|------------------------------------------------------------------------------------------------------------------------|
 | device_lists                     | DeviceLists       | Optional. Information on e2e device updates. Note: only present on an incremental sync.                                |
-| device_one_time_keys_count       | {string: integer}  | Optional. For each key algorithm, the number of unclaimed one-time keys currently held on the server for this device.  If an algorithm is unlisted, the count for that algorithm is assumed to be zero.  If this entire parameter is missing, the count for all algorithms is assumed to be zero.  |
+| device_one_time_keys_count       | {string: integer} | **Required if any unclaimed one-time keys exist.** For each key algorithm, the number of unclaimed one-time keys currently held on the server for this device. If the count for an algorithm is zero, servers MAY omit that algorithm. If the count for all algorithms is zero, servers MAY omit this parameter entirely. |
 | device_unused_fallback_key_types | [string]          | **Required.** The unused fallback key algorithms.                                                                      |
 
 `DeviceLists`
 
 | Parameter | Type     | Description                                                                                                                                                      |
-|------------|-----------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|-----------|----------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | changed   | [string] | List of users who have updated their device identity or cross-signing keys, or who now share an encrypted room with the client since the previous sync response. |
 | left      | [string] | List of users with whom we do not share any encrypted rooms anymore since the previous sync response.                                                            |
 

content/rooms/fragments/v3-handling-redactions.md

@@ -17,6 +17,9 @@ is met:
 2. The domain of the redaction event's `sender` matches that of the
    original event's `sender`.
 
+Note that the first condition holds true even when the `sender` doesn't have a
+high enough power level to send the type of event that they're redacting.
+
 If the server would apply a redaction, the redaction event is also sent
 to clients. Otherwise, the server simply waits for a valid partner event
 to arrive where it can then re-check the above.