Add experimental support for MSC4360: Sliding Sync Threads Extension

changelog.d/19005.feature

@@ -0,0 +1 @@
+Add experimental support for MSC4360: Sliding Sync Threads Extension.

synapse/api/constants.py

@@ -272,6 +272,9 @@ class EventContentFields:
     M_TOPIC: Final = "m.topic"
     M_TEXT: Final = "m.text"
 
+    # Event relations
+    RELATIONS: Final = "m.relates_to"
+
 
 class EventUnsignedContentFields:
     """Fields found inside the 'unsigned' data on events"""
@@ -360,3 +363,10 @@ class Direction(enum.Enum):
 class ProfileFields:
     DISPLAYNAME: Final = "displayname"
     AVATAR_URL: Final = "avatar_url"
+
+
+class MRelatesToFields:
+    """Fields found inside m.relates_to content blocks."""
+
+    EVENT_ID: Final = "event_id"
+    REL_TYPE: Final = "rel_type"

synapse/config/experimental.py

@@ -593,3 +593,6 @@ def read_config(
         # MSC4306: Thread Subscriptions
         # (and MSC4308: Thread Subscriptions extension to Sliding Sync)
         self.msc4306_enabled: bool = experimental.get("msc4306_enabled", False)
+
+        # MSC4360: Threads Extension to Sliding Sync
+        self.msc4360_enabled: bool = experimental.get("msc4360_enabled", False)

synapse/handlers/relations.py

@@ -105,8 +105,6 @@ async def get_relations(
     ) -> JsonDict:
         """Get related events of a event, ordered by topological ordering.
 
-        TODO Accept a PaginationConfig instead of individual pagination parameters.
-
         Args:
             requester: The user requesting the relations.
             event_id: Fetch events that relate to this event ID.

synapse/handlers/sliding_sync/__init__.py

@@ -305,6 +305,7 @@ async def handle_room(room_id: str) -> None:
             # account data, read receipts, typing indicators, to-device messages, etc).
             actual_room_ids=set(relevant_room_map.keys()),
             actual_room_response_map=rooms,
+            room_membership_for_user_at_to_token_map=room_membership_for_user_map,
             from_token=from_token,
             to_token=to_token,
         )