From 9cf29e4a6c289c2e848a9fd4385df90758d78d6e Mon Sep 17 00:00:00 2001
From: spaced4ndy <8711996+spaced4ndy@users.noreply.github.com>
Date: Fri, 7 Aug 2026 23:49:27 +0400
Subject: [PATCH 1/2] server: prevent concurrent SKEY commands from overwriting
 queue sender key

---
 src/Simplex/Messaging/Server/QueueStore/Postgres.hs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/Simplex/Messaging/Server/QueueStore/Postgres.hs b/src/Simplex/Messaging/Server/QueueStore/Postgres.hs
index ce1cf25db..09574b91d 100644
--- a/src/Simplex/Messaging/Server/QueueStore/Postgres.hs
+++ b/src/Simplex/Messaging/Server/QueueStore/Postgres.hs
@@ -341,8 +341,10 @@ instance StoreQueueClass q => QueueStoreClass q (PostgresQueueStore q) where
   secureQueue st sq sKey =
     withQueueRec sq "secureQueue" $ \q -> do
       verify q
+      -- `verify` checks a snapshot of the queue record that a concurrent command may have
+      -- invalidated, so the update repeats the check atomically - the loser matches no rows.
       assertUpdated $ withDB' "secureQueue" st $ \db ->
-        DB.execute db "UPDATE msg_queues SET sender_key = ? WHERE recipient_id = ? AND deleted_at IS NULL" (sKey, rId)
+        DB.execute db "UPDATE msg_queues SET sender_key = ? WHERE recipient_id = ? AND deleted_at IS NULL AND (sender_key IS NULL OR sender_key = ?)" (sKey, rId, sKey)
       atomically $ writeTVar (queueRec sq) $ Just q {senderKey = Just sKey}
       withLog "secureQueue" st $ \s -> logSecureQueue s rId sKey
     where

From 2e46e56aa87196492e5ed3d944857818a721cf05 Mon Sep 17 00:00:00 2001
From: spaced4ndy <8711996+spaced4ndy@users.noreply.github.com>
Date: Sat, 8 Aug 2026 00:08:04 +0400
Subject: [PATCH 2/2] wip

---
 src/Simplex/Messaging/Server/QueueStore/Postgres.hs | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/Simplex/Messaging/Server/QueueStore/Postgres.hs b/src/Simplex/Messaging/Server/QueueStore/Postgres.hs
index 09574b91d..8738bee99 100644
--- a/src/Simplex/Messaging/Server/QueueStore/Postgres.hs
+++ b/src/Simplex/Messaging/Server/QueueStore/Postgres.hs
@@ -341,8 +341,6 @@ instance StoreQueueClass q => QueueStoreClass q (PostgresQueueStore q) where
   secureQueue st sq sKey =
     withQueueRec sq "secureQueue" $ \q -> do
       verify q
-      -- `verify` checks a snapshot of the queue record that a concurrent command may have
-      -- invalidated, so the update repeats the check atomically - the loser matches no rows.
       assertUpdated $ withDB' "secureQueue" st $ \db ->
         DB.execute db "UPDATE msg_queues SET sender_key = ? WHERE recipient_id = ? AND deleted_at IS NULL AND (sender_key IS NULL OR sender_key = ?)" (sKey, rId, sKey)
       atomically $ writeTVar (queueRec sq) $ Just q {senderKey = Just sKey}