Fix live multi-turn: pass the resolved drug, stop did-you-mean garbage

apps/web/app/_components/ChatPanel.tsx

@@ -21,10 +21,20 @@ export interface ChatPanelProps {
   className?: string;
 }
 
+const ERROR_MESSAGE =
+  "Hệ thống tạm thời không phản hồi. Vui lòng thử lại — nếu vẫn lỗi, có thể dịch vụ tra cứu đang tạm ngưng.";
+
 export function ChatPanel({ onCitationClick, className }: ChatPanelProps) {
   const [messages, setMessages] = useState<ChatMessage[]>([]);
   const [input, setInput] = useState("");
   const [isSending, setIsSending] = useState(false);
+  // One id per chat session, so follow-ups ("còn trẻ em thì sao?") resolve
+  // against the same conversation on the backend.
+  const [conversationId] = useState(() =>
+    typeof crypto !== "undefined" && crypto.randomUUID
+      ? crypto.randomUUID()
+      : `conv-${Date.now()}`
+  );
 
   async function handleSubmit(event: React.FormEvent) {
     event.preventDefault();
@@ -41,8 +51,20 @@ export function ChatPanel({ onCitationClick, className }: ChatPanelProps) {
     setInput("");
     setIsSending(true);
     try {
-      const response = await sendChatMessage(content);
+      const response = await sendChatMessage(content, conversationId);
       setMessages((prev) => [...prev, response.message]);
+    } catch {
+      // Never leave the user staring at their own message with no reply: an
+      // error is surfaced as a labelled bubble, not swallowed silently.
+      setMessages((prev) => [
+        ...prev,
+        {
+          id: `error-${messages.length}`,
+          role: "assistant",
+          content: ERROR_MESSAGE,
+          createdAt: new Date().toISOString(),
+        },
+      ]);
     } finally {
       setIsSending(false);
     }