From 537f03860e1586cd4a1e42fbebf33eb45acf4ea0 Mon Sep 17 00:00:00 2001
From: Quentin Gliech <quentingliech@gmail.com>
Date: Fri, 14 Aug 2026 15:11:30 +0200
Subject: [PATCH] Take an optional unthreaded receipt position in
 `_get_unread_counts_by_pos_txn`

The caller passed either the user's latest unthreaded receipt or, when they
had none, the stream ordering of their join, leaving the callee unable to tell
the two apart. Pass `None` instead and do the membership lookup in the callee,
so the fallback is explicit.

(cherry picked from commit e08b4dabdb8d04da97f7a7ce8d51564017995887)
---
 .../databases/main/event_push_actions.py      | 53 +++++++++----------
 1 file changed, 26 insertions(+), 27 deletions(-)

diff --git a/synapse/storage/databases/main/event_push_actions.py b/synapse/storage/databases/main/event_push_actions.py
index afbbe6b61a..86a9bed0bb 100644
--- a/synapse/storage/databases/main/event_push_actions.py
+++ b/synapse/storage/databases/main/event_push_actions.py
@@ -533,24 +533,8 @@ class EventPushActionsWorkerStore(ReceiptsWorkerStore, StreamWorkerStore, SQLBas
             receipt_types=(ReceiptTypes.READ, ReceiptTypes.READ_PRIVATE),
         )
 
-        if result:
-            _, stream_ordering = result
-
-        else:
-            # If the user has no receipts in the room, retrieve the stream ordering for
-            # the latest membership event from this user in this room (which we assume is
-            # a join).
-            event_id = self.db_pool.simple_select_one_onecol_txn(
-                txn=txn,
-                table="local_current_membership",
-                keyvalues={"room_id": room_id, "user_id": user_id},
-                retcol="event_id",
-            )
-
-            stream_ordering = self.get_stream_id_for_event_txn(txn, event_id)
-
         return self._get_unread_counts_by_pos_txn(
-            txn, room_id, user_id, stream_ordering
+            txn, room_id, user_id, result[1] if result else None
         )
 
     def _get_unread_counts_by_pos_txn(
@@ -558,7 +542,7 @@ class EventPushActionsWorkerStore(ReceiptsWorkerStore, StreamWorkerStore, SQLBas
         txn: LoggingTransaction,
         room_id: str,
         user_id: str,
-        unthreaded_receipt_stream_ordering: int,
+        unthreaded_receipt_stream_ordering: int | None,
     ) -> RoomNotifCounts:
         """Get the number of unread messages for a user/room that have happened
         since the given stream ordering.
@@ -568,8 +552,8 @@ class EventPushActionsWorkerStore(ReceiptsWorkerStore, StreamWorkerStore, SQLBas
             room_id: The room ID to get unread counts for.
             user_id: The user ID to get unread counts for.
             unthreaded_receipt_stream_ordering: The stream ordering of the user's latest
-                unthreaded receipt in the room. If there are no unthreaded receipts,
-                the stream ordering of the user's join event.
+                unthreaded receipt in the room, or None if they have none. In that case
+                we count from the user's latest membership event instead.
 
         Returns:
             A RoomNotifCounts object containing the notification count, the
@@ -577,6 +561,21 @@ class EventPushActionsWorkerStore(ReceiptsWorkerStore, StreamWorkerStore, SQLBas
             and threads.
         """
 
+        if unthreaded_receipt_stream_ordering is not None:
+            from_stream_ordering = unthreaded_receipt_stream_ordering
+        else:
+            # If the user has no unthreaded receipt in the room, retrieve the stream
+            # ordering for the latest membership event from this user in this room
+            # (which we assume is a join).
+            event_id = self.db_pool.simple_select_one_onecol_txn(
+                txn=txn,
+                table="local_current_membership",
+                keyvalues={"room_id": room_id, "user_id": user_id},
+                retcol="event_id",
+            )
+
+            from_stream_ordering = self.get_stream_id_for_event_txn(txn, event_id)
+
         main_counts = NotifCounts()
         thread_counts: dict[str, NotifCounts] = {}
 
@@ -631,12 +630,12 @@ class EventPushActionsWorkerStore(ReceiptsWorkerStore, StreamWorkerStore, SQLBas
             (
                 user_id,
                 room_id,
-                unthreaded_receipt_stream_ordering,
+                from_stream_ordering,
                 *receipts_args,
                 room_id,
                 user_id,
-                unthreaded_receipt_stream_ordering,
-                unthreaded_receipt_stream_ordering,
+                from_stream_ordering,
+                from_stream_ordering,
             ),
         )
         summarised_threads = set()
@@ -670,11 +669,11 @@ class EventPushActionsWorkerStore(ReceiptsWorkerStore, StreamWorkerStore, SQLBas
             (
                 user_id,
                 room_id,
-                unthreaded_receipt_stream_ordering,
+                from_stream_ordering,
                 *receipts_args,
                 user_id,
                 room_id,
-                unthreaded_receipt_stream_ordering,
+                from_stream_ordering,
             ),
         )
         for highlight_count, thread_id in txn:
@@ -748,11 +747,11 @@ class EventPushActionsWorkerStore(ReceiptsWorkerStore, StreamWorkerStore, SQLBas
             (
                 user_id,
                 room_id,
-                unthreaded_receipt_stream_ordering,
+                from_stream_ordering,
                 *receipts_args,
                 user_id,
                 room_id,
-                unthreaded_receipt_stream_ordering,
+                from_stream_ordering,
                 *thread_id_args,
             ),
         )