Support a thread_id parameter for receipts.

changelog.d/13782.feature

@@ -0,0 +1 @@
+Experimental support for thread-specific receipts ([MSC3771](https://github.com/matrix-org/matrix-spec-proposals/pull/3771)).

synapse/config/experimental.py

@@ -83,6 +83,8 @@ def read_config(self, config: JsonDict, **kwargs: Any) -> None:
         # MSC3786 (Add a default push rule to ignore m.room.server_acl events)
         self.msc3786_enabled: bool = experimental.get("msc3786_enabled", False)
 
+        # MSC3771: Thread read receipts
+        self.msc3771_enabled: bool = experimental.get("msc3771_enabled", False)
         # MSC3772: A push rule for mutual relations.
         self.msc3772_enabled: bool = experimental.get("msc3772_enabled", False)
 

synapse/handlers/receipts.py

@@ -91,13 +91,23 @@ async def _received_remote_receipt(self, origin: str, content: JsonDict) -> None
                         )
                         continue
 
+                    # Check if these receipts apply to a thread.
+                    thread_id = None
+                    data = user_values.get("data", {})
+                    if isinstance(data, dict):
+                        thread_id = data.get("thread_id")
+                        # If the thread ID is invalid, consider it missing.
+                        if not isinstance(thread_id, str):
+                            thread_id = None
+
                     receipts.append(
                         ReadReceipt(
                             room_id=room_id,
                             receipt_type=receipt_type,
                             user_id=user_id,
                             event_ids=user_values["event_ids"],
-                            data=user_values.get("data", {}),
+                            thread_id=thread_id,
+                            data=data,
                         )
                     )
 
@@ -146,7 +156,12 @@ async def _handle_new_receipts(self, receipts: List[ReadReceipt]) -> bool:
         return True
 
     async def received_client_receipt(
-        self, room_id: str, receipt_type: str, user_id: str, event_id: str
+        self,
+        room_id: str,
+        receipt_type: str,
+        user_id: str,
+        event_id: str,
+        thread_id: Optional[str],
     ) -> None:
         """Called when a client tells us a local user has read up to the given
         event_id in the room.
@@ -156,6 +171,7 @@ async def received_client_receipt(
             receipt_type=receipt_type,
             user_id=user_id,
             event_ids=[event_id],
+            thread_id=thread_id,
             data={"ts": int(self.clock.time_msec())},
         )
 

synapse/replication/tcp/client.py

@@ -427,7 +427,8 @@ async def _on_new_receipts(
                 receipt.receipt_type,
                 receipt.user_id,
                 [receipt.event_id],
-                receipt.data,
+                thread_id=receipt.thread_id,
+                data=receipt.data,
             )
             await self.federation_sender.send_read_receipt(receipt_info)
 

synapse/rest/client/read_marker.py

@@ -83,6 +83,8 @@ async def on_POST(
                     receipt_type,
                     user_id=requester.user.to_string(),
                     event_id=event_id,
+                    # Setting the thread ID is not possible with the /read_markers endpoint.
+                    thread_id=None,
                 )
 
         return 200, {}

synapse/rest/client/receipts.py

@@ -49,6 +49,7 @@ def __init__(self, hs: "HomeServer"):
             ReceiptTypes.READ_PRIVATE,
             ReceiptTypes.FULLY_READ,
         }
+        self._msc3771_enabled = hs.config.experimental.msc3771_enabled
 
     async def on_POST(
         self, request: SynapseRequest, room_id: str, receipt_type: str, event_id: str
@@ -61,7 +62,17 @@ async def on_POST(
                 f"Receipt type must be {', '.join(self._known_receipt_types)}",
             )
 
-        parse_json_object_from_request(request, allow_empty_body=False)
+        body = parse_json_object_from_request(request)
+
+        # Pull the thread ID, if one exists.
+        thread_id = None
+        if self._msc3771_enabled:
+            if "thread_id" in body:
+                thread_id = body.get("thread_id")
+                if not thread_id or not isinstance(thread_id, str):
+                    raise SynapseError(
+                        400, "thread_id field must be a non-empty string"
+                    )
 
         await self.presence_handler.bump_presence_active_time(requester.user)
 
@@ -77,6 +88,7 @@ async def on_POST(
                 receipt_type,
                 user_id=requester.user.to_string(),
                 event_id=event_id,
+                thread_id=thread_id,
             )
 
         return 200, {}

synapse/rest/client/versions.py

@@ -103,6 +103,8 @@ def on_GET(self, request: Request) -> Tuple[int, JsonDict]:
                     "org.matrix.msc3030": self.config.experimental.msc3030_enabled,
                     # Adds support for thread relations, per MSC3440.
                     "org.matrix.msc3440.stable": True,  # TODO: remove when "v1.3" is added above
+                    # Support for thread read receipts.
+                    "org.matrix.msc3771": self.config.experimental.msc3771_enabled,
                     # Allows moderators to fetch redacted event content as described in MSC2815
                     "fi.mau.msc2815": self.config.experimental.msc2815_enabled,
                     # Adds support for login token requests as per MSC3882

synapse/types.py

@@ -835,6 +835,7 @@ class ReadReceipt:
     receipt_type: str
     user_id: str
     event_ids: List[str]
+    thread_id: Optional[str]
     data: JsonDict
 
 

tests/federation/test_federation_sender.py

@@ -49,7 +49,12 @@ def test_send_receipts(self):
 
         sender = self.hs.get_federation_sender()
         receipt = ReadReceipt(
-            "room_id", "m.read", "user_id", ["event_id"], {"ts": 1234}
+            "room_id",
+            "m.read",
+            "user_id",
+            ["event_id"],
+            thread_id=None,
+            data={"ts": 1234},
         )
         self.successResultOf(defer.ensureDeferred(sender.send_read_receipt(receipt)))
 
@@ -89,7 +94,12 @@ def test_send_receipts_with_backoff(self):
 
         sender = self.hs.get_federation_sender()
         receipt = ReadReceipt(
-            "room_id", "m.read", "user_id", ["event_id"], {"ts": 1234}
+            "room_id",
+            "m.read",
+            "user_id",
+            ["event_id"],
+            thread_id=None,
+            data={"ts": 1234},
         )
         self.successResultOf(defer.ensureDeferred(sender.send_read_receipt(receipt)))
 
@@ -121,7 +131,12 @@ def test_send_receipts_with_backoff(self):
 
         # send the second RR
         receipt = ReadReceipt(
-            "room_id", "m.read", "user_id", ["other_id"], {"ts": 1234}
+            "room_id",
+            "m.read",
+            "user_id",
+            ["other_id"],
+            thread_id=None,
+            data={"ts": 1234},
         )
         self.successResultOf(defer.ensureDeferred(sender.send_read_receipt(receipt)))
         self.pump()