Sliding Sync: Add receipts extension (MSC3960) (#17489)

[MSC3960](matrix-org/matrix-spec-proposals#3960): Receipts extension

Based on
[MSC3575](matrix-org/matrix-spec-proposals#3575):
Sliding Sync

Author: MadLittleMods

changelog.d/17489.feature

@@ -0,0 +1 @@
+Add receipts extension support to experimental [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575) Sliding Sync `/sync` endpoint.

synapse/handlers/receipts.py

@@ -286,8 +286,10 @@ async def get_new_events(
         room_ids: Iterable[str],
         is_guest: bool,
         explicit_room_id: Optional[str] = None,
+        to_key: Optional[MultiWriterStreamToken] = None,
     ) -> Tuple[List[JsonMapping], MultiWriterStreamToken]:
-        to_key = self.get_current_key()
+        if to_key is None:
+            to_key = self.get_current_key()
 
         if from_key == to_key:
             return [], to_key

synapse/handlers/sliding_sync.py

@@ -1150,6 +1150,12 @@ async def encode_extensions(
                 },
             }
 
+        if extensions.receipts is not None:
+            serialized_extensions["receipts"] = {
+                # Same as the the top-level `account_data.events` field in Sync v2.
+                "rooms": extensions.receipts.room_id_to_receipt_map,
+            }
+
         return serialized_extensions
 
 

synapse/rest/client/sync.py

@@ -152,7 +152,7 @@ class SlidingSyncResult:
     Attributes:
         next_pos: The next position token in the sliding window to request (next_batch).
         lists: Sliding window API. A map of list key to list results.
-        rooms: Room subscription API. A map of room ID to room subscription to room results.
+        rooms: Room subscription API. A map of room ID to room results.
         extensions: Extensions API. A map of extension key to extension results.
     """
 
@@ -361,12 +361,28 @@ def __bool__(self) -> bool:
                     self.global_account_data_map or self.account_data_by_room_map
                 )
 
+        @attr.s(slots=True, frozen=True, auto_attribs=True)
+        class ReceiptsExtension:
+            """The Receipts extension (MSC3960)
+
+            Attributes:
+                room_id_to_receipt_map: Mapping from room_id to `m.receipt` event (type, content)
+            """
+
+            room_id_to_receipt_map: Mapping[str, JsonMapping]
+
+            def __bool__(self) -> bool:
+                return bool(self.room_id_to_receipt_map)
+
         to_device: Optional[ToDeviceExtension] = None
         e2ee: Optional[E2eeExtension] = None
         account_data: Optional[AccountDataExtension] = None
+        receipts: Optional[ReceiptsExtension] = None
 
         def __bool__(self) -> bool:
-            return bool(self.to_device or self.e2ee or self.account_data)
+            return bool(
+                self.to_device or self.e2ee or self.account_data or self.receipts
+            )
 
     next_pos: SlidingSyncStreamToken
     lists: Dict[str, SlidingWindowList]

synapse/types/handlers/__init__.py

@@ -342,9 +342,27 @@ class AccountDataExtension(RequestBodyModel):
             # Process all room subscriptions defined in the Room Subscription API. (This is the default.)
             rooms: Optional[List[StrictStr]] = ["*"]
 
+        class ReceiptsExtension(RequestBodyModel):
+            """The Receipts extension (MSC3960)
+
+            Attributes:
+                enabled
+                lists: List of list keys (from the Sliding Window API) to apply this
+                    extension to.
+                rooms: List of room IDs (from the Room Subscription API) to apply this
+                    extension to.
+            """
+
+            enabled: Optional[StrictBool] = False
+            # Process all lists defined in the Sliding Window API. (This is the default.)
+            lists: Optional[List[StrictStr]] = ["*"]
+            # Process all room subscriptions defined in the Room Subscription API. (This is the default.)
+            rooms: Optional[List[StrictStr]] = ["*"]
+
         to_device: Optional[ToDeviceExtension] = None
         e2ee: Optional[E2eeExtension] = None
         account_data: Optional[AccountDataExtension] = None
+        receipts: Optional[ReceiptsExtension] = None
 
     conn_id: Optional[str]