Suppress duplicate valueChanged after writeValue

Add m_pendingWrite flag to skip the write-path valueAttributeUpdated
emission and let only the monitored item deliver the authoritative
server value. Mirrors the existing m_pendingRangeWrite pattern.

1 files changed, 16 insertions, 7 deletions

diff --git a/src/OpcUaMonitoredNode.cpp b/src/OpcUaMonitoredNode.cpp
index 290a1c2..beec934 100644
--- a/src/OpcUaMonitoredNode.cpp
+++ b/src/OpcUaMonitoredNode.cpp
@@ -179,6 +179,7 @@ OpcUaMonitoredNode::teardownNode ()
   emit infoChanged ();
 
   m_valueType = QOpcUa::Types::Undefined;
+  m_pendingWrite = false;
   m_pendingRangeWrite = false;
 
   if (m_writable)
@@ -312,11 +313,14 @@ OpcUaMonitoredNode::handleAttributeUpdated (QOpcUa::NodeAttribute attr,
 void
 OpcUaMonitoredNode::handleValueUpdated (const QVariant &value)
 {
-  // After a range write, Qt emits valueAttributeUpdated with only the
-  // partial written value instead of the full array. Ignore this
-  // update and let the monitored item deliver the correct full array
-  // on the next data change notification.
-  if (m_pendingRangeWrite)
+  // After a write, Qt emits valueAttributeUpdated from the write path
+  // before the server's monitored item notification arrives. For regular
+  // writes this is a duplicate; for range writes it carries only the
+  // partial written value. Ignore both and let monitoring deliver the
+  // authoritative value. Removing this guard would give an immediate UI
+  // update that does not reflect the actual server state, which could be
+  // useful for optimistic updates.
+  if (m_pendingWrite || m_pendingRangeWrite)
     return;
 
   // Store the new value pushed by the OPC UA monitored item.
@@ -357,6 +361,7 @@ OpcUaMonitoredNode::handleAttributeWritten (QOpcUa::NodeAttribute attr,
   if (attr != QOpcUa::NodeAttribute::Value)
     return;
 
+  m_pendingWrite = false;
   m_pendingRangeWrite = false;
 
   bool ok = (statusCode == QOpcUa::Good);
@@ -560,9 +565,13 @@ OpcUaMonitoredNode::writeValue (const QVariant &value)
       return;
     }
 
+  m_pendingWrite = true;
   if (!m_node->writeValueAttribute (coerced, m_valueType))
-    emit writeCompleted (false,
-                         QStringLiteral ("Write request failed to dispatch"));
+    {
+      m_pendingWrite = false;
+      emit writeCompleted (
+          false, QStringLiteral ("Write request failed to dispatch"));
+    }
 }
 
 void