refactor: 标题生成重构、UI样式优化、测试增强

- 将标题生成逻辑提取为独立函数，提前到Agent调用前非阻塞执行

- 修复模型/供应商不存在时的HTTP状态码 500→400

- ChatPanel: 分离模型选择useEffect、CSS类替代内联样式、按钮样式统一

- use-conversations: fetchConversations/fetchMessages改用handleResponse去重

- 聊天面板滚动优化(scroll-behavior: smooth, overflow-anchor: auto)

- 测试: mock支持onFinish回调，新增首次消息标题生成测试

- 移除未使用的SendMessageRequest接口

src/web/consoles/workbench/components/chat/ChatPanel.tsx

@@ -70,21 +70,11 @@ export function ChatPanel({ conversationId, onConversationCreated, projectId }:
       setInput("");
       setMessages([]);
       try {
-        const convPromise = fetchConversation(projectId, conversationId);
         const msgPromise = fetchRef.current(projectId, conversationId);
 
-        const conv = await convPromise;
         const data = await msgPromise;
         if (cancelled) return;
 
-        const firstTextId = textModels[0]?.id;
-        if (firstTextId && textModels.every((m) => m.id !== conv.modelId)) {
-          setSelectedModelId(firstTextId);
-          void updateConversation(projectId, conversationId, { modelId: firstTextId });
-        } else {
-          setSelectedModelId(conv.modelId);
-        }
-
         const history = data.items
           .filter((m: { role: string }) => m.role === "user" || m.role === "assistant")
           .reverse()
@@ -109,7 +99,22 @@ export function ChatPanel({ conversationId, onConversationCreated, projectId }:
     return () => {
       cancelled = true;
     };
-  }, [conversationId, projectId, setMessages, message, textModels]);
+  }, [conversationId, projectId, setMessages, message]);
+
+  useEffect(() => {
+    if (!conversationId) return;
+    const firstTextId = textModels[0]?.id;
+    if (!firstTextId) return;
+
+    void fetchConversation(projectId, conversationId).then((conv) => {
+      if (textModels.every((m) => m.id !== conv.modelId)) {
+        setSelectedModelId(firstTextId);
+        void updateConversation(projectId, conversationId, { modelId: firstTextId });
+      } else {
+        setSelectedModelId(conv.modelId);
+      }
+    });
+  }, [conversationId, textModels, projectId]);
 
   useEffect(() => {
     scrollRef.current?.scrollTo({ behavior: "smooth", top: scrollRef.current.scrollHeight });
@@ -213,18 +218,39 @@ export function ChatPanel({ conversationId, onConversationCreated, projectId }:
       const buttons: React.ReactNode[] = [];
 
       buttons.push(
-        <Button icon={<CopyOutlined />} key="copy" onClick={() => handleCopy(msg)} size="small" type="text" />,
+        <Button
+          className="btn-dimmed"
+          icon={<CopyOutlined />}
+          key="copy"
+          onClick={() => handleCopy(msg)}
+          size="small"
+          type="text"
+        />,
       );
 
       if (isLastUser && !isEditing) {
         buttons.push(
-          <Button icon={<EditOutlined />} key="edit" onClick={() => handleEditStart(msg)} size="small" type="text" />,
+          <Button
+            className="btn-dimmed"
+            icon={<EditOutlined />}
+            key="edit"
+            onClick={() => handleEditStart(msg)}
+            size="small"
+            type="text"
+          />,
         );
       }
 
       if (isLastAssistant) {
         buttons.push(
-          <Button icon={<RedoOutlined />} key="regenerate" onClick={handleRegenerate} size="small" type="text" />,
+          <Button
+            className="btn-dimmed"
+            icon={<RedoOutlined />}
+            key="regenerate"
+            onClick={handleRegenerate}
+            size="small"
+            type="text"
+          />,
         );
       }
 
@@ -238,8 +264,8 @@ export function ChatPanel({ conversationId, onConversationCreated, projectId }:
       <div className="app-chat-panel">
         <div className="chat-welcome-area">
           <Flex align="center" gap={12} vertical>
-            <RobotOutlined style={{ color: "var(--ant-color-primary)", fontSize: 48 }} />
-            <Typography.Title level={3} style={{ margin: 0 }}>
+            <RobotOutlined className="welcome-icon" />
+            <Typography.Title className="welcome-title" level={3}>
               你好，我是阿福
             </Typography.Title>
             <Typography.Text type="secondary">有什么我可以帮助你的吗？</Typography.Text>
@@ -274,6 +300,7 @@ export function ChatPanel({ conversationId, onConversationCreated, projectId }:
           <Flex gap={8} vertical>
             {messages.map((msg, idx) => (
               <Card
+                classNames={{ extra: "card-extra-actions" }}
                 extra={getCardExtra(msg, idx)}
                 key={msg.id}
                 size="small"

src/web/hooks/use-conversations.ts

@@ -29,20 +29,12 @@ export async function fetchConversation(projectId: string, conversationId: strin
 
 export async function fetchConversations(projectId: string): Promise<ConversationListResponse> {
   const response = await fetch(`/api/projects/${projectId}/conversations?pageSize=100`);
-  if (!response.ok) {
-    const body = (await response.json().catch(() => null)) as null | { error?: string };
-    throw new Error(body?.error ?? `HTTP ${response.status}`);
-  }
-  return response.json() as Promise<ConversationListResponse>;
+  return handleResponse(response, (data) => data as ConversationListResponse);
 }
 
 export async function fetchMessages(projectId: string, conversationId: string): Promise<MessageListResponse> {
   const response = await fetch(`/api/projects/${projectId}/conversations/${conversationId}/messages?pageSize=200`);
-  if (!response.ok) {
-    const body = (await response.json().catch(() => null)) as null | { error?: string };
-    throw new Error(body?.error ?? `HTTP ${response.status}`);
-  }
-  return response.json() as Promise<MessageListResponse>;
+  return handleResponse(response, (data) => data as MessageListResponse);
 }
 
 export async function updateConversation(

src/web/styles.css

@@ -184,7 +184,9 @@ body {
   flex: 1;
   min-height: 0;
   overflow: auto;
+  overflow-anchor: auto;
   padding-left: var(--ant-padding-sm);
+  scroll-behavior: smooth;
 }
 
 .chat-loading-indicator {
@@ -228,14 +230,23 @@ body {
   color: var(--ant-color-error);
 }
 
+.welcome-icon {
+  color: var(--ant-color-primary);
+  font-size: 48px;
+}
+
+.welcome-title {
+  margin: 0;
+}
+
 .chat-model-select {
   width: 180px;
 }
 
-.ant-card-extra .ant-btn-text {
+.card-extra-actions .btn-dimmed {
   color: var(--ant-color-text-quaternary);
 }
 
-.ant-card-extra .ant-btn-text:hover {
+.card-extra-actions .btn-dimmed:hover {
   color: var(--ant-color-text-secondary);
 }