diff --git a/app.py b/app.py
index cdc223e..ac9582a 100644
--- a/app.py
+++ b/app.py
@@ -811,7 +811,10 @@ def chat_claude(
                         "message_chunk",
                         {
                             "id": msg_id,
-                            "content": f"**{username} ({model_name}):**\n\n{content}",
+                            "content": content,
+                            "username": username,
+                            "model_name": model_name,
+                            "is_first_chunk": True,
                         },
                         room=room.name,
                     )
@@ -969,7 +972,10 @@ def chat_gpt(username, room_name, model_name="gpt-4o-mini"):
                     "message_chunk",
                     {
                         "id": msg_id,
-                        "content": f"**{username} ({model_name}):**\n\n{content}",
+                        "content": content,
+                        "username": username,
+                        "model_name": model_name,
+                        "is_first_chunk": True,
                     },
                     room=room.name,
                 )
@@ -1083,7 +1089,10 @@ def chat_llama(username, room_name, model_name="mistral-7b-instruct-v0.2.Q3_K_L.
                     "message_chunk",
                     {
                         "id": msg_id,
-                        "content": f"**{username} ({model_name}):**\n\n{content}",
+                        "content": content,
+                        "username": username,
+                        "model_name": model_name,
+                        "is_first_chunk": True,
                     },
                     room=room.name,
                 )
diff --git a/templates/chat.html b/templates/chat.html
index 29c82d5..2d4e57c 100644
--- a/templates/chat.html
+++ b/templates/chat.html
@@ -762,12 +762,18 @@ socket.on("message_chunk", (data) => {
 
     // Append the chunk to the buffer
     messageBuffers[data.id] += data.content;
-
-    // Process the entire buffer with marked and set it as the content of the target element
-    const sanitizedContent = DOMPurify.sanitize(marked.marked(messageBuffers[data.id]), dompurify_config);
+    
+    // Build the content for display (includes header for first chunk)
+    let displayContent = messageBuffers[data.id];
+    if (data.is_first_chunk && data.username && data.model_name) {
+        displayContent = `**${data.username} (${data.model_name}):**\n\n${displayContent}`;
+    }
+    
+    // Process the display content with marked and set it as the content of the target element
+    const sanitizedContent = DOMPurify.sanitize(marked.marked(displayContent), dompurify_config);
     targetMessageElement.innerHTML = sanitizedContent;
 
-    // Store the raw markdown in a data attribute for later use in editing
+    // Store the raw markdown in a data attribute for later use in editing (without header for clean editing)
     targetMessageElement.dataset.rawMarkdown = messageBuffers[data.id];
 
     // Apply syntax highlighting to code blocks within the content