feat(api): 实现消息合并 API，支持工具调用显示

- 新增 MergedMessage、ToolCallInfo 类型定义
- 创建 message-merger.ts 消息合并工具
- 更新 sessions 路由使用合并后的消息格式
- 前端新增 ToolCallsDisplay 组件展示工具调用
- 工具调用显示状态、时长，可展开查看参数和结果

packages/ui/src/components/ChatMessage.tsx

@@ -2,13 +2,25 @@
  * Chat Message Component
  */
 
-import { User, Bot, Copy, Check } from 'lucide-react';
-import { motion } from 'framer-motion';
+import {
+  User,
+  Bot,
+  Copy,
+  Check,
+  Wrench,
+  ChevronDown,
+  ChevronRight,
+  Clock,
+  AlertCircle,
+  CheckCircle2,
+  Loader2,
+} from 'lucide-react';
+import { motion, AnimatePresence } from 'framer-motion';
 import { useState, forwardRef } from 'react';
 import { cn } from '../utils/cn';
 import { fadeInUp, smoothTransition } from '../utils/animations';
 import { Markdown } from './Markdown';
-import type { Message } from '../api/client.js';
+import type { Message, ToolCallInfo, ToolCallStatus } from '../api/types.js';
 
 interface ChatMessageProps {
   message: Message;
@@ -59,6 +71,10 @@ export const ChatMessage = forwardRef<HTMLDivElement, ChatMessageProps>(
               {copied ? <Check size={14} className="text-green-500" /> : <Copy size={14} />}
             </button>
           </div>
+          {/* 工具调用显示 */}
+          {!isUser && message.toolCalls && message.toolCalls.length > 0 && (
+            <ToolCallsDisplay toolCalls={message.toolCalls} />
+          )}
           <div className="message-content text-gray-200">
             {isUser ? (
               // 用户消息：保持原样显示
@@ -135,3 +151,137 @@ export function TypingIndicator() {
     </motion.div>
   );
 }
+
+// ============ 工具调用显示组件 ============
+
+/**
+ * 获取工具状态图标
+ */
+function getStatusIcon(status: ToolCallStatus) {
+  switch (status) {
+    case 'pending':
+      return <Clock size={14} className="text-yellow-500" />;
+    case 'running':
+      return <Loader2 size={14} className="text-blue-500 animate-spin" />;
+    case 'completed':
+      return <CheckCircle2 size={14} className="text-green-500" />;
+    case 'error':
+      return <AlertCircle size={14} className="text-red-500" />;
+  }
+}
+
+/**
+ * 格式化执行时长
+ */
+function formatDuration(ms?: number): string {
+  if (!ms) return '';
+  if (ms < 1000) return `${ms}ms`;
+  return `${(ms / 1000).toFixed(1)}s`;
+}
+
+/**
+ * 工具调用列表容器
+ */
+interface ToolCallsDisplayProps {
+  toolCalls: ToolCallInfo[];
+}
+
+function ToolCallsDisplay({ toolCalls }: ToolCallsDisplayProps) {
+  return (
+    <div className="mb-3 space-y-2">
+      {toolCalls.map((toolCall) => (
+        <ToolCallItem key={toolCall.id} toolCall={toolCall} />
+      ))}
+    </div>
+  );
+}
+
+/**
+ * 单个工具调用项
+ */
+interface ToolCallItemProps {
+  toolCall: ToolCallInfo;
+}
+
+function ToolCallItem({ toolCall }: ToolCallItemProps) {
+  const [expanded, setExpanded] = useState(false);
+  const hasDetails =
+    Object.keys(toolCall.arguments).length > 0 ||
+    toolCall.result !== undefined ||
+    toolCall.error !== undefined;
+
+  return (
+    <div className="border border-gray-700 rounded-lg overflow-hidden bg-gray-800/30">
+      {/* 头部：工具名称、状态、时长 */}
+      <button
+        onClick={() => hasDetails && setExpanded(!expanded)}
+        className={cn(
+          'w-full flex items-center gap-2 px-3 py-2 text-sm',
+          hasDetails && 'hover:bg-gray-700/50 cursor-pointer',
+          !hasDetails && 'cursor-default'
+        )}
+      >
+        <Wrench size={14} className="text-gray-400 flex-shrink-0" />
+        <span className="font-mono text-gray-200 flex-1 text-left truncate">
+          {toolCall.name}
+        </span>
+        {getStatusIcon(toolCall.status)}
+        {toolCall.duration && (
+          <span className="text-xs text-gray-500">{formatDuration(toolCall.duration)}</span>
+        )}
+        {hasDetails && (
+          <span className="text-gray-500">
+            {expanded ? <ChevronDown size={14} /> : <ChevronRight size={14} />}
+          </span>
+        )}
+      </button>
+
+      {/* 展开的详情 */}
+      <AnimatePresence>
+        {expanded && hasDetails && (
+          <motion.div
+            initial={{ height: 0, opacity: 0 }}
+            animate={{ height: 'auto', opacity: 1 }}
+            exit={{ height: 0, opacity: 0 }}
+            transition={{ duration: 0.2 }}
+            className="border-t border-gray-700 overflow-hidden"
+          >
+            <div className="px-3 py-2 space-y-2 text-xs">
+              {/* 参数 */}
+              {Object.keys(toolCall.arguments).length > 0 && (
+                <div>
+                  <div className="text-gray-500 mb-1">Arguments:</div>
+                  <pre className="bg-gray-900 rounded p-2 overflow-x-auto text-gray-300 max-h-48 overflow-y-auto">
+                    {JSON.stringify(toolCall.arguments, null, 2)}
+                  </pre>
+                </div>
+              )}
+
+              {/* 结果 */}
+              {toolCall.result !== undefined && (
+                <div>
+                  <div className="text-gray-500 mb-1">Result:</div>
+                  <pre className="bg-gray-900 rounded p-2 overflow-x-auto text-green-300 max-h-48 overflow-y-auto">
+                    {typeof toolCall.result === 'string'
+                      ? toolCall.result
+                      : JSON.stringify(toolCall.result, null, 2)}
+                  </pre>
+                </div>
+              )}
+
+              {/* 错误 */}
+              {toolCall.error && (
+                <div>
+                  <div className="text-red-400 mb-1">Error:</div>
+                  <pre className="bg-gray-900 rounded p-2 overflow-x-auto text-red-300 max-h-48 overflow-y-auto">
+                    {toolCall.error}
+                  </pre>
+                </div>
+              )}
+            </div>
+          </motion.div>
+        )}
+      </AnimatePresence>
+    </div>
+  );
+}