fix tool result messages not containing latest user question

changelogs/fragments/10758.yml

@@ -0,0 +1,2 @@
+fix:
+- [BUG][Chat] fix tool result messages not containing latest user question ([#10758](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/10758))

src/plugins/chat/public/components/chat_window.tsx

@@ -60,6 +60,12 @@ function ChatWindowContent({
   const [input, setInput] = useState('');
   const [isStreaming, setIsStreaming] = useState(false);
   const [currentRunId, setCurrentRunId] = useState<string | null>(null);
+
+  const timelineRef = React.useRef<Message[]>(timeline);
+
+  React.useEffect(() => {
+    timelineRef.current = timeline;
+  }, [timeline]);
 
   // Create the event handler using useMemo
   const eventHandler = useMemo(
@@ -69,9 +75,9 @@ function ChatWindowContent({
         chatService,
         setTimeline,
         setIsStreaming,
-        () => timeline
+        () => timelineRef.current
       ),
-    [service, chatService, timeline] // Only recreate if services change
+    [service, chatService]
   );
 
   // Register actions

src/plugins/chat/public/services/chat_event_handler.ts

@@ -300,16 +300,6 @@ export class ChatEventHandler {
           result: result.data,
         });
 
-        // Add tool result message to timeline
-        const toolMessage: ToolMessage = {
-          id: `tool-result-${toolCallId}`,
-          role: 'tool',
-          content: typeof result.data === 'string' ? result.data : JSON.stringify(result.data),
-          toolCallId,
-        };
-
-        this.onTimelineUpdate((prev) => [...prev, toolMessage]);
-
         // Send tool result back to assistant if chatService is available
         if (this.chatService && (this.chatService as any).sendToolResult) {
           await this.sendToolResultToAssistant(toolCallId, result.data);
@@ -494,13 +484,16 @@ export class ChatEventHandler {
    */
   private async sendToolResultToAssistant(toolCallId: string, result: any): Promise<void> {
     try {
-      const messages = this.getTimeline(); // Now pass timeline directly - no transformation needed
-      const { observable } = await (this.chatService as any).sendToolResult(
+      const messages = this.getTimeline();
+
+      const { observable, toolMessage } = await (this.chatService as any).sendToolResult(
         toolCallId,
         result,
         messages
       );
 
+      this.onTimelineUpdate((prev) => [...prev, toolMessage]);
+
       // Set streaming state and subscribe to the response stream
       this.onStreamingStateChange(true);