feat(聊天): 实现 AI 消息重新生成功能

- 消息 API 新增 DELETE 方法支持删除单条消息
- useStreamChat Hook 添加 regenerateMessage 方法
- 聊天页面添加 handleRegenerate 处理逻辑
- MessageBubble 组件添加重新生成按钮（仅 AI 消息显示）
- MessageBubble 使用 Tooltip 替代原生 title 属性
- 移除未使用的 ActionButton 组件和点赞/踩按钮

src/app/api/messages/[messageId]/route.ts

@@ -117,3 +117,48 @@ export async function GET(request: Request, { params }: RouteParams) {
     );
   }
 }
+
+/**
+ * DELETE /api/messages/[messageId] - 删除消息
+ * 用于重新生成功能：删除 AI 消息后重新生成
+ */
+export async function DELETE(request: Request, { params }: RouteParams) {
+  try {
+    const { messageId } = await params;
+
+    if (!messageId) {
+      return NextResponse.json(
+        { error: 'Message ID is required' },
+        { status: 400 }
+      );
+    }
+
+    // 查找消息
+    const existingMessage = await db.query.messages.findFirst({
+      where: eq(messages.messageId, messageId),
+    });
+
+    if (!existingMessage) {
+      return NextResponse.json(
+        { error: 'Message not found' },
+        { status: 404 }
+      );
+    }
+
+    // 删除消息
+    await db
+      .delete(messages)
+      .where(eq(messages.messageId, messageId));
+
+    return NextResponse.json({
+      success: true,
+      message: 'Message deleted successfully',
+    });
+  } catch (error) {
+    console.error('Delete message error:', error);
+    return NextResponse.json(
+      { error: 'Failed to delete message' },
+      { status: 500 }
+    );
+  }
+}

src/app/chat/[id]/page.tsx

@@ -53,6 +53,7 @@ export default function ChatPage({ params }: PageProps) {
     sendMessage,
     stopGeneration,
     setInitialMessages,
+    regenerateMessage,
   } = useStreamChat();
 
   // 当前选择的模型和工具
@@ -265,6 +266,30 @@ export default function ChatPage({ params }: PageProps) {
     setEnableThinking(!enableThinking);
   };
 
+  // 重新生成 AI 消息
+  const handleRegenerate = async (messageId: string) => {
+    if (isStreaming) return; // 正在生成时不允许重新生成
+
+    const result = await regenerateMessage(messageId);
+    if (!result) {
+      console.error('Failed to regenerate message');
+      return;
+    }
+
+    const { userMessage } = result;
+
+    // 重新发送用户消息
+    // 注意：历史消息中的图片已经是 base64 格式，保存在 uploadedImages 中
+    // sendMessage 会重新添加用户消息和 AI 消息占位
+    await sendMessage({
+      conversationId: chatId,
+      message: userMessage.content,
+      model: selectedModelId,
+      tools: enabledTools,
+      enableThinking,
+    });
+  };
+
   // 切换模型（持久化到数据库）
   const handleModelChange = async (modelId: string) => {
     if (!conversation || modelId === selectedModelId) return;
@@ -506,6 +531,7 @@ export default function ChatPage({ params }: PageProps) {
                   uploadedImages={message.uploadedImages}
                   uploadedDocuments={message.uploadedDocuments}
                   pyodideStatus={message.pyodideStatus}
+                  onRegenerate={message.role === 'assistant' && !isStreaming ? handleRegenerate : undefined}
                 />
               ))
             )}

src/components/features/MessageBubble.tsx

@@ -1,9 +1,10 @@
 'use client';
 
 import { useState } from 'react';
-import { Copy, ThumbsUp, ThumbsDown, RefreshCw, ChevronDown, ChevronUp, Brain, Loader2, AlertCircle, Check, FileText, FileCode } from 'lucide-react';
+import { Copy, RefreshCw, ChevronDown, ChevronUp, Brain, Loader2, AlertCircle, Check, FileText, FileCode } from 'lucide-react';
 import { Avatar } from '@/components/ui/Avatar';
 import { AILogo } from '@/components/ui/AILogo';
+import { Tooltip } from '@/components/ui/Tooltip';
 import { MarkdownRenderer } from '@/components/markdown/MarkdownRenderer';
 import { CodeExecutionResult, PyodideLoading } from '@/components/features/CodeExecutionResult';
 import { ImageLightbox } from '@/components/ui/ImageLightbox';
@@ -30,6 +31,8 @@ interface MessageBubbleProps {
     message: string;
     progress?: number;
   };
+  /** 重新生成回调（仅对 AI 消息有效），传入消息 ID */
+  onRegenerate?: (messageId: string) => void;
 }
 
 // 格式化文件大小
@@ -49,7 +52,7 @@ function getDocumentIcon(type: string) {
   return FileText;
 }
 
-export function MessageBubble({ message, user, thinkingContent, isStreaming, error, images, uploadedImages, uploadedDocuments, pyodideStatus }: MessageBubbleProps) {
+export function MessageBubble({ message, user, thinkingContent, isStreaming, error, images, uploadedImages, uploadedDocuments, pyodideStatus, onRegenerate }: MessageBubbleProps) {
   const isUser = message.role === 'user';
   const [thinkingExpanded, setThinkingExpanded] = useState(false);
   const [copied, setCopied] = useState(false);
@@ -158,8 +161,7 @@ export function MessageBubble({ message, user, thinkingContent, isStreaming, err
           {/* 悬停显示复制按钮 */}
           <button
             onClick={handleCopy}
-            className="absolute -bottom-8 right-0 opacity-0 group-hover:opacity-100 transition-opacity duration-200 flex items-center gap-1 px-2 py-1 text-xs text-[var(--color-text-tertiary)] hover:text-[var(--color-text-secondary)] hover:bg-[var(--color-bg-hover)] rounded-md"
+            className="absolute -bottom-8 right-0 opacity-0 group-hover:opacity-100 transition-opacity duration-200 flex items-center gap-1 px-2 py-1 text-xs text-[var(--color-text-tertiary)] hover:text-[var(--color-text-secondary)] hover:bg-[var(--color-bg-hover)] rounded-md cursor-pointer"
-            title={copied ? '已复制' : '复制'}
           >
             {copied ? (
               <>
@@ -307,16 +309,25 @@ export function MessageBubble({ message, user, thinkingContent, isStreaming, err
           {!isStreaming && message.content && (
             <>
               <div className="flex items-center gap-1 mt-4 pt-3">
+                <Tooltip content={copied ? '已复制' : '复制'}>
                   <button
                     onClick={handleCopy}
-                  className="w-8 h-8 flex items-center justify-center rounded-lg text-[var(--color-text-tertiary)] hover:bg-[var(--color-bg-hover)] hover:text-[var(--color-text-secondary)] transition-colors"
+                    className="w-8 h-8 flex items-center justify-center rounded-lg text-[var(--color-text-tertiary)] hover:bg-[var(--color-bg-hover)] hover:text-[var(--color-text-secondary)] transition-colors cursor-pointer"
-                  title={copied ? '已复制' : '复制'}
                   >
                     {copied ? <Check size={16} className="text-green-500" /> : <Copy size={16} />}
                   </button>
-                <ActionButton icon={ThumbsUp} title="好的回答" />
+                </Tooltip>
-                <ActionButton icon={ThumbsDown} title="不好的回答" />
+                {/* 重新生成按钮 */}
-                <ActionButton icon={RefreshCw} title="重新生成" />
+                {onRegenerate && (
+                  <Tooltip content="重新生成">
+                    <button
+                      onClick={() => onRegenerate(message.id)}
+                      className="w-8 h-8 flex items-center justify-center rounded-lg text-[var(--color-text-tertiary)] hover:bg-[var(--color-bg-hover)] hover:text-[var(--color-text-secondary)] transition-colors cursor-pointer"
+                    >
+                      <RefreshCw size={16} />
+                    </button>
+                  </Tooltip>
+                )}
               </div>
 
               {/* 免责声明 */}
@@ -346,24 +357,6 @@ export function MessageBubble({ message, user, thinkingContent, isStreaming, err
   );
 }
 
-interface ActionButtonProps {
-  icon: React.ComponentType<{ size?: number }>;
-  title: string;
-  onClick?: () => void;
-}
-
-function ActionButton({ icon: Icon, title, onClick }: ActionButtonProps) {
-  return (
-    <button
-      onClick={onClick}
-      className="w-8 h-8 flex items-center justify-center rounded-lg text-[var(--color-text-tertiary)] hover:bg-[var(--color-bg-hover)] hover:text-[var(--color-text-secondary)] transition-colors"
-      title={title}
-    >
-      <Icon size={16} />
-    </button>
-  );
-}
-
 /**
  * 工具调用结果显示组件
  * 专门处理代码执行结果和图片显示

src/hooks/useStreamChat.ts

@@ -527,6 +527,55 @@ export function useStreamChat() {
     setMessages(initialMessages);
   }, []);
 
+  /**
+   * 重新生成消息
+   * @param assistantMessageId 要重新生成的 AI 消息 ID
+   * @returns 对应的用户消息信息，用于重新发送；如果找不到则返回 null
+   */
+  const regenerateMessage = useCallback(async (assistantMessageId: string): Promise<{
+    userMessage: ChatMessage;
+  } | null> => {
+    // 1. 在消息列表中找到该 AI 消息的索引
+    const assistantIndex = messages.findIndex(m => m.id === assistantMessageId);
+    if (assistantIndex === -1) {
+      console.error('[regenerateMessage] AI message not found:', assistantMessageId);
+      return null;
+    }
+
+    // 2. 找到对应的用户消息（AI 消息的前一条）
+    const userIndex = assistantIndex - 1;
+    if (userIndex < 0 || messages[userIndex].role !== 'user') {
+      console.error('[regenerateMessage] User message not found for AI message:', assistantMessageId);
+      return null;
+    }
+
+    const userMessage = { ...messages[userIndex] };
+
+    // 3. 尝试从数据库删除 AI 消息（只有保存到数据库的消息才需要删除）
+    // 临时消息 ID 格式为 'assistant-timestamp'，数据库消息 ID 是 nanoid 格式
+    if (!assistantMessageId.startsWith('assistant-')) {
+      try {
+        const response = await fetch(`/api/messages/${assistantMessageId}`, {
+          method: 'DELETE',
+        });
+        if (!response.ok) {
+          console.warn('[regenerateMessage] Failed to delete message from database:', await response.text());
+        }
+      } catch (err) {
+        console.warn('[regenerateMessage] Error deleting message from database:', err);
+      }
+    }
+
+    // 4. 从前端状态中移除用户消息、AI 消息及其后的所有消息
+    // 因为 sendMessage 会重新添加用户消息和 AI 消息占位
+    setMessages(prev => prev.slice(0, userIndex));
+
+    // 5. 返回用户消息信息
+    return {
+      userMessage,
+    };
+  }, [messages]);
+
   return {
     messages,
     isStreaming,
@@ -535,5 +584,6 @@ export function useStreamChat() {
     stopGeneration,
     clearMessages,
     setInitialMessages,
+    regenerateMessage,
   };
 }