fix: 使用 wrappedSendMessage 保存用户消息到独立状态

1. 创建 wrappedSendMessage 包装函数
2. 在发送消息时同时保存用户消息到 appendedMessages
3. 这样即使 useChat 重置消息状态，用户消息也会保留在 mergedMessages 中

Co-authored-by: Cursor <cursoragent@cursor.com>

components/chat.tsx

@@ -3,7 +3,7 @@
 import { useChat } from "@ai-sdk/react";
 import { DefaultChatTransport } from "ai";
 import { useRouter, useSearchParams } from "next/navigation";
-import { useEffect, useMemo, useRef, useState } from "react";
+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import useSWR, { useSWRConfig } from "swr";
 import { unstable_serialize } from "swr/infinite";
 import { ChatHeader } from "@/components/chat-header";
@@ -356,28 +356,8 @@ export function Chat({
       // 🆕 生成完成，清除持久化状态
       completeGeneration();
       console.log("[Chat] onFinish called");
-      
-      // 🆕 在流式传输完成后，将 appendedMessages 合并到 messages
-      // 延迟执行以确保 useChat 内部状态已稳定
-      setTimeout(() => {
-        setAppendedMessages((prevAppended) => {
-          if (prevAppended.length > 0) {
-            console.log("[Chat] Merging appendedMessages to messages:", prevAppended.length);
-            setMessages((prevMessages) => {
-              // 过滤掉已存在的消息
-              const newMessages = prevAppended.filter(
-                (appended) => !prevMessages.some((m) => m.id === appended.id)
-              );
-              if (newMessages.length > 0) {
-                console.log("[Chat] Actually adding new messages:", newMessages.length);
-                return [...prevMessages, ...newMessages];
-              }
-              return prevMessages;
-            });
-          }
-          return []; // 清空 appendedMessages
-        });
-      }, 100);
+      // 🆕 不再尝试在 onFinish 中合并消息，完全依赖 mergedMessages
+      // 消息会在下次页面加载时从数据库正确获取
     },
     onError: (error) => {
       if (error instanceof ChatSDKError) {
@@ -393,6 +373,27 @@ export function Chat({
     },
   });
 
+  // 🆕 包装 sendMessage，在发送时保存用户消息到 appendedMessages
+  // 这样即使 useChat 重置消息状态，用户消息也会保留在 mergedMessages 中
+  const wrappedSendMessage = useCallback((message: Parameters<typeof sendMessage>[0]) => {
+    // 保存用户消息到 appendedMessages
+    const textPart = message?.parts?.find((p: any) => p.type === "text") as any;
+    const userMessage: ChatMessage = {
+      id: generateUUID(),
+      role: "user",
+      content: textPart?.text || "",
+      createdAt: new Date(),
+      parts: message?.parts || [],
+      attachments: (message as any)?.attachments || [],
+    } as ChatMessage;
+    
+    console.log("[Chat] Saving user message to appendedMessages:", userMessage.id);
+    setAppendedMessages((prev) => [...prev, userMessage]);
+    
+    // 调用原始的 sendMessage
+    return sendMessage(message);
+  }, [sendMessage]);
+
   // 调试：监控聊天状态变化 & 持久化生成状态
   // 使用 ref 来访问最新的 modelsData，避免依赖数组问题
   const modelsDataRef = useRef(modelsData);
@@ -430,7 +431,7 @@ export function Chat({
 
   useEffect(() => {
     if (query && !hasAppendedQuery) {
-      sendMessage({
+      wrappedSendMessage({
         role: "user" as const,
         parts: [{ type: "text", text: query }],
       });
@@ -1113,7 +1114,7 @@ export function Chat({
           isReadonly={isReadonly}
           messages={mergedMessages}
           regenerate={regenerate}
-          sendMessage={sendMessage}
+          sendMessage={wrappedSendMessage}
           selectedModelId={currentModelId}
           setMessages={setMessages}
           status={status}
@@ -1143,7 +1144,7 @@ export function Chat({
               onModelChange={setCurrentModelId}
               selectedModelId={currentModelId}
               selectedVisibilityType={visibilityType}
-              sendMessage={sendMessage}
+              sendMessage={wrappedSendMessage}
               setAttachments={setAttachments}
               setInput={setInput}
               setMessages={setMessages}
@@ -1176,7 +1177,7 @@ export function Chat({
         regenerate={regenerate}
         selectedModelId={currentModelId}
         selectedVisibilityType={visibilityType}
-        sendMessage={sendMessage}
+        sendMessage={wrappedSendMessage}
         setAttachments={setAttachments}
         setInput={setInput}
         setMessages={setMessages}