diff --git a/app/radio.py b/app/radio.py
index ac58834..a9b19e2 100644
--- a/app/radio.py
+++ b/app/radio.py
@@ -192,6 +192,9 @@ class RadioManager:
         if not blocking:
             if self._operation_lock.locked():
                 raise RadioOperationBusyError(f"Radio is busy (operation: {name})")
+            # In single-threaded asyncio the lock cannot be acquired between the
+            # check above and the await below (no other coroutine runs until we
+            # yield). The await returns immediately for an uncontested lock.
             await self._operation_lock.acquire()
         else:
             await self._operation_lock.acquire()
diff --git a/app/repository/messages.py b/app/repository/messages.py
index d83e947..65c4799 100644
--- a/app/repository/messages.py
+++ b/app/repository/messages.py
@@ -557,10 +557,11 @@ class MessageRepository:
     @staticmethod
     async def increment_ack_count(message_id: int) -> int:
         """Increment ack count and return the new value."""
-        await db.conn.execute("UPDATE messages SET acked = acked + 1 WHERE id = ?", (message_id,))
-        await db.conn.commit()
-        cursor = await db.conn.execute("SELECT acked FROM messages WHERE id = ?", (message_id,))
+        cursor = await db.conn.execute(
+            "UPDATE messages SET acked = acked + 1 WHERE id = ? RETURNING acked", (message_id,)
+        )
         row = await cursor.fetchone()
+        await db.conn.commit()
         return row["acked"] if row else 1
 
     @staticmethod
diff --git a/frontend/src/hooks/useConversationMessages.ts b/frontend/src/hooks/useConversationMessages.ts
index 5c11b80..660c5da 100644
--- a/frontend/src/hooks/useConversationMessages.ts
+++ b/frontend/src/hooks/useConversationMessages.ts
@@ -372,6 +372,8 @@ export function useConversationMessages(
   const olderAbortControllerRef = useRef<AbortController | null>(null);
   const newerAbortControllerRef = useRef<AbortController | null>(null);
   const fetchingConversationIdRef = useRef<string | null>(null);
+  const activeConversationRef = useRef(activeConversation);
+  activeConversationRef.current = activeConversation;
   const latestReconcileRequestIdRef = useRef(0);
   const pendingReconnectReconcileRef = useRef(false);
   const messagesRef = useRef<Message[]>([]);
@@ -664,9 +666,11 @@ export function useConversationMessages(
   }, [activeConversation]);
 
   const reconcileOnReconnect = useCallback(() => {
-    if (!isMessageConversation(activeConversation)) {
-      return;
-    }
+    // Read the current conversation from the ref rather than closing over
+    // activeConversation, so that a conversation switch during WS reconnect
+    // targets the right conversation instead of a stale capture.
+    const current = activeConversationRef.current;
+    if (!isMessageConversation(current)) return;
 
     if (hasNewerMessagesRef.current) {
       pendingReconnectReconcileRef.current = true;
@@ -677,8 +681,8 @@ export function useConversationMessages(
     const controller = new AbortController();
     const requestId = latestReconcileRequestIdRef.current + 1;
     latestReconcileRequestIdRef.current = requestId;
-    reconcileFromBackend(activeConversation, controller.signal, requestId);
-  }, [activeConversation, reconcileFromBackend]);
+    reconcileFromBackend(current, controller.signal, requestId);
+  }, [reconcileFromBackend]);
 
   useEffect(() => {
     if (abortControllerRef.current) {