diff --git a/backend/agentpress/processor/llm_response_processor.py b/backend/agentpress/processor/llm_response_processor.py
index 0f879f1f..21985a79 100644
--- a/backend/agentpress/processor/llm_response_processor.py
+++ b/backend/agentpress/processor/llm_response_processor.py
@@ -133,19 +133,11 @@ class LLMResponseProcessor:
                 if self.tool_calls_accumulated:
                     message["tool_calls"] = self.tool_calls_accumulated
 
-                if not hasattr(self, '_message_added'):
-                    await self.results_adder.add_initial_response(
-                        self.thread_id,
-                        self.content_buffer,
-                        self.tool_calls_accumulated
-                    )
-                    self._message_added = True
-                else:
-                    await self.results_adder.update_response(
-                        self.thread_id,
-                        self.content_buffer,
-                        self.tool_calls_accumulated
-                    )
+                await self.results_adder.update_response(
+                    self.thread_id,
+                    self.content_buffer,
+                    self.tool_calls_accumulated
+                )
 
                 # Handle stream completion
                 if chunk.choices[0].finish_reason:
diff --git a/backend/agentpress/processor/xml/xml_results_adder.py b/backend/agentpress/processor/xml/xml_results_adder.py
index c8835f87..b41ec01c 100644
--- a/backend/agentpress/processor/xml/xml_results_adder.py
+++ b/backend/agentpress/processor/xml/xml_results_adder.py
@@ -55,15 +55,23 @@ class XMLResultsAdder(ResultsAdderBase):
             - Creates initial message if none exists
             - Preserves XML structure in updates
         """
-        if not self.message_added:
-            await self.add_initial_response(thread_id, content, tool_calls)
-            return
-        
         message = {
             "role": "assistant",
             "content": content
         }
-        await self.update_message(thread_id, message)
+        
+        # Check if an assistant message already exists in the thread
+        existing_messages = await self.get_messages(thread_id)
+        assistant_msg = next((msg for msg in reversed(existing_messages) 
+                           if msg['role'] == 'assistant'), None)
+        
+        if assistant_msg:
+            # Update existing message
+            await self.update_message(thread_id, message)
+        else:
+            # Add new message
+            await self.add_message(thread_id, message)
+            self.message_added = True
     
     async def add_tool_result(self, thread_id: str, result: Dict[str, Any]):
         """Add XML tool result with proper referencing.