Prefer room v9 for restricted rooms. (#10772)

Hint to clients via the room capabilities API (MSC3244) that
room version 9 should be preferred for creating a room with
restricted join rules (instead of room version 8).

2 files changed, 2 insertions, 1 deletions

diff --git a/changelog.d/10772.feature b/changelog.d/10772.feature
new file mode 100644

index 0000000000..4a550711f6
--- /dev/null
+++ b/changelog.d/10772.feature
@@ -0,0 +1 @@
+Prefer [room version 9](https://github.com/matrix-org/matrix-doc/pull/3375) for restricted rooms per the [room version caapabilities](https://github.com/matrix-org/matrix-doc/pull/3244) API.
diff --git a/synapse/api/room_versions.py b/synapse/api/room_versions.py

index a19be6707a..61d9c658a9 100644
--- a/synapse/api/room_versions.py
+++ b/synapse/api/room_versions.py
@@ -324,7 +324,7 @@ MSC3244_CAPABILITIES = {
         ),
         RoomVersionCapability(
             "restricted",
-            RoomVersions.V8,
+            RoomVersions.V9,
             lambda room_version: room_version.msc3083_join_rules,
         ),
     )