feat: 新增会话历史侧边栏，支持新建/切换/删除/重命名会话

类似 ChatGPT 的侧边栏布局，消息历史持久化到 localStorage。

- 新增 SessionSummary 类型和 localStorage 读写函数
- 新增 useSessionList Hook 管理会话列表 CRUD
- 新增 SessionSidebar 组件（展开/折叠、行内重命名）
- App.tsx 协调 useSessionList 和 useVisionSession
- 消息变化时自动持久化，切换/新建会话时保存并加载
- 新增 i18n 翻译 key（中/英/日）

frontend/src/App.css

@@ -208,6 +208,193 @@ body {
   overflow: hidden;
 }
 
+/* ---- 会话历史侧边栏 ---- */
+
+.sidebar {
+  width: 260px;
+  flex-shrink: 0;
+  display: flex;
+  flex-direction: column;
+  background: var(--color-surface-1);
+  border-right: 1px solid var(--color-border);
+  overflow: hidden;
+}
+
+.sidebar--collapsed {
+  width: 48px;
+  align-items: center;
+  padding: 8px 0;
+  gap: 8px;
+}
+
+.sidebar__header {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  padding: 12px;
+  border-bottom: 1px solid var(--color-border);
+  flex-shrink: 0;
+}
+
+.sidebar__toggle {
+  background: none;
+  border: none;
+  color: var(--color-text-muted);
+  cursor: pointer;
+  font-size: 1rem;
+  padding: 6px 8px;
+  border-radius: var(--radius-sm);
+  transition: background var(--transition-fast), color var(--transition-fast);
+}
+
+.sidebar__toggle:hover {
+  background: var(--color-surface-2);
+  color: var(--color-text);
+}
+
+.sidebar__new-btn {
+  background: none;
+  border: 1px solid var(--color-border);
+  color: var(--color-text);
+  cursor: pointer;
+  font-size: 0.82rem;
+  padding: 6px 10px;
+  border-radius: var(--radius-sm);
+  transition: background var(--transition-fast);
+}
+
+.sidebar__new-btn:hover {
+  background: var(--color-surface-2);
+}
+
+.sidebar__new-btn--full {
+  flex: 1;
+  text-align: left;
+}
+
+.sidebar__list {
+  flex: 1;
+  overflow-y: auto;
+  padding: 6px;
+}
+
+.sidebar__empty {
+  padding: 24px 12px;
+  text-align: center;
+  color: var(--color-text-muted);
+  font-size: 0.82rem;
+}
+
+.sidebar__item {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  padding: 10px 12px;
+  border-radius: var(--radius-sm);
+  cursor: pointer;
+  transition: background var(--transition-fast);
+  position: relative;
+}
+
+.sidebar__item:hover {
+  background: var(--color-surface-2);
+}
+
+.sidebar__item:hover .sidebar__item-actions {
+  opacity: 1;
+}
+
+.sidebar__item--active {
+  background: var(--color-surface-2);
+  border-left: 3px solid var(--color-primary);
+}
+
+.sidebar__item-content {
+  flex: 1;
+  min-width: 0;
+}
+
+.sidebar__item-title {
+  font-size: 0.85rem;
+  font-weight: 500;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  color: var(--color-text);
+}
+
+.sidebar__item-meta {
+  font-size: 0.72rem;
+  color: var(--color-text-muted);
+  margin-top: 2px;
+  display: flex;
+  gap: 8px;
+}
+
+.sidebar__item-actions {
+  display: flex;
+  gap: 2px;
+  opacity: 0;
+  transition: opacity var(--transition-fast);
+  flex-shrink: 0;
+}
+
+.sidebar__action-btn {
+  background: none;
+  border: none;
+  cursor: pointer;
+  font-size: 0.75rem;
+  padding: 4px 6px;
+  border-radius: var(--radius-sm);
+  color: var(--color-text-muted);
+  transition: background var(--transition-fast), color var(--transition-fast);
+}
+
+.sidebar__action-btn:hover {
+  background: var(--color-surface-3);
+  color: var(--color-text);
+}
+
+.sidebar__action-btn--danger:hover {
+  color: #e74c3c;
+}
+
+.sidebar__edit {
+  display: flex;
+  gap: 4px;
+  width: 100%;
+}
+
+.sidebar__edit-input {
+  flex: 1;
+  font-size: 0.82rem;
+  padding: 4px 8px;
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-sm);
+  background: var(--color-surface-1);
+  color: var(--color-text);
+  outline: none;
+}
+
+.sidebar__edit-input:focus {
+  border-color: var(--color-primary);
+}
+
+.sidebar__edit-btn {
+  background: none;
+  border: none;
+  cursor: pointer;
+  font-size: 0.85rem;
+  padding: 4px 8px;
+  border-radius: var(--radius-sm);
+  color: var(--color-text-muted);
+}
+
+.sidebar__edit-btn:hover {
+  background: var(--color-surface-2);
+  color: var(--color-text);
+}
+
 /* ---- 左侧视频面板 ---- */
 
 .video-panel {

frontend/src/App.tsx

@@ -1,12 +1,14 @@
 // ============================================================
-// CamTalk — 主应用组件（Web 端双栏布局）
+// CamTalk — 主应用组件（Web 端三栏布局：侧边栏 + 视频 + 聊天）
 // ============================================================
 
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { useVisionSession } from "./hooks/useVisionSession";
+import { useSessionList } from "./hooks/useSessionList";
 import { VideoPreview } from "./components/VideoPreview";
 import { ChatPanel } from "./components/ChatPanel";
 import { ConfigPanel } from "./components/ConfigPanel";
+import { SessionSidebar } from "./components/SessionSidebar";
 import { ToastContainer } from "./components/Toast";
 import { loadConfig, loadTheme, saveTheme } from "./lib/storage";
 import { I18nContext, parseLocale, t } from "./lib/i18n";
@@ -14,11 +16,12 @@ import type { Locale } from "./lib/i18n";
 import type { Theme } from "./types";
 import "./App.css";
 
-/** 内部组件，确保在 I18nContext.Provider 内部使用 useVisionSession */
+/** 内部组件，确保在 I18nContext.Provider 内部使用 hooks */
 function AppContent() {
   const [showConfig, setShowConfig] = useState(false);
   const [theme, setTheme] = useState<Theme>(loadTheme);
   const [elapsed, setElapsed] = useState(0);
+  const [sidebarCollapsed, setSidebarCollapsed] = useState(false);
   const timerRef = useRef<ReturnType<typeof setInterval> | null>(null);
 
   // 切换主题时更新 <html> 的 data-theme 属性
@@ -37,8 +40,21 @@ function AppContent() {
     return `${m.toString().padStart(2, "0")}:${sec.toString().padStart(2, "0")}`;
   };
 
+  // ---- 会话列表 ----
+  const {
+    sessions,
+    activeSessionId,
+    createSession,
+    deleteSession,
+    renameSession,
+    persistSession,
+    selectSession,
+  } = useSessionList();
+
+  // ---- 视觉会话 ----
   const {
     messages,
+    setMessages,
     currentReply,
     isProcessing,
     isAudioPlaying,
@@ -93,6 +109,58 @@ function AppContent() {
 
   const { t: tr } = useMemo(() => ({ t: (key: string) => t(key, parseLocale(config.language)) }), [config.language]);
 
+  // ---- 初始化：如果没有会话，创建一个 ----
+  const initializedRef = useRef(false);
+  useEffect(() => {
+    if (!initializedRef.current) {
+      initializedRef.current = true;
+      if (sessions.length === 0) {
+        createSession();
+      }
+    }
+  }, [sessions.length, createSession]);
+
+  // ---- 自动保存：messages 变化时持久化到当前会话 ----
+  const messagesRef = useRef(messages);
+  useEffect(() => { messagesRef.current = messages; }, [messages]);
+
+  useEffect(() => {
+    if (activeSessionId && messages.length > 0) {
+      persistSession(activeSessionId, messages);
+    }
+  }, [messages, activeSessionId, persistSession]);
+
+  // ---- 侧边栏操作 ----
+  const handleNewSession = useCallback(() => {
+    createSession();
+    setMessages([]);
+    // 如果已连接，断开
+    if (connectionStatus === "connected") {
+      stopSession();
+    }
+  }, [createSession, setMessages, connectionStatus, stopSession]);
+
+  const handleSelectSession = useCallback((id: string) => {
+    // 保存当前会话
+    if (activeSessionId && messagesRef.current.length > 0) {
+      persistSession(activeSessionId, messagesRef.current);
+    }
+    // 如果已连接，断开
+    if (connectionStatus === "connected") {
+      stopSession();
+    }
+    // 加载目标会话
+    const loaded = selectSession(id);
+    setMessages(loaded);
+  }, [activeSessionId, persistSession, connectionStatus, stopSession, selectSession, setMessages]);
+
+  const handleDeleteSession = useCallback((id: string) => {
+    deleteSession(id);
+    if (id === activeSessionId) {
+      setMessages([]);
+    }
+  }, [deleteSession, activeSessionId, setMessages]);
+
   return (
     <div className="app">
       {/* ---- 顶部导航栏 ---- */}
@@ -134,9 +202,21 @@ function AppContent() {
         />
       )}
 
-      {/* ---- 主体：左侧视频 + 右侧聊天 ---- */}
+      {/* ---- 主体：侧边栏 + 视频 + 聊天 ---- */}
       <div className="workspace">
-        {/* 左侧：视频预览 + 控制栏 */}
+        {/* 最左侧：会话历史侧边栏 */}
+        <SessionSidebar
+          sessions={sessions}
+          activeSessionId={activeSessionId}
+          collapsed={sidebarCollapsed}
+          onToggleCollapse={() => setSidebarCollapsed((v) => !v)}
+          onNewSession={handleNewSession}
+          onSelectSession={handleSelectSession}
+          onDeleteSession={handleDeleteSession}
+          onRenameSession={renameSession}
+        />
+
+        {/* 中间：视频预览 + 控制栏 */}
         <div className="video-panel">
           <div className="video-container">
             <VideoPreview ref={videoRef} isStreaming={!!stream} />

frontend/src/components/SessionSidebar/index.tsx

@@ -0,0 +1,160 @@
+// ============================================================
+// SessionSidebar — 会话历史侧边栏
+// 职责：展示会话列表、新建/切换/删除/重命名会话
+// ============================================================
+
+import { useState } from "react";
+import { useI18n } from "../../lib/i18n";
+import type { SessionSummary } from "../../types";
+
+interface SessionSidebarProps {
+  sessions: SessionSummary[];
+  activeSessionId: string | null;
+  collapsed: boolean;
+  onToggleCollapse: () => void;
+  onNewSession: () => void;
+  onSelectSession: (id: string) => void;
+  onDeleteSession: (id: string) => void;
+  onRenameSession: (id: string, title: string) => void;
+}
+
+/** 格式化相对时间 */
+function formatRelativeTime(ts: number): string {
+  const now = Date.now();
+  const diff = now - ts;
+  const min = 60 * 1000;
+  const hour = 60 * min;
+  const day = 24 * hour;
+
+  if (diff < min) return "刚刚";
+  if (diff < hour) return `${Math.floor(diff / min)}分钟前`;
+  if (diff < day) return `${Math.floor(diff / hour)}小时前`;
+  if (diff < 2 * day) return "昨天";
+  if (diff < 7 * day) return `${Math.floor(diff / day)}天前`;
+  const d = new Date(ts);
+  return `${d.getMonth() + 1}/${d.getDate()}`;
+}
+
+export function SessionSidebar({
+  sessions,
+  activeSessionId,
+  collapsed,
+  onToggleCollapse,
+  onNewSession,
+  onSelectSession,
+  onDeleteSession,
+  onRenameSession,
+}: SessionSidebarProps) {
+  const { t } = useI18n();
+  const [editingId, setEditingId] = useState<string | null>(null);
+  const [editTitle, setEditTitle] = useState("");
+
+  const handleStartRename = (id: string, currentTitle: string) => {
+    setEditingId(id);
+    setEditTitle(currentTitle);
+  };
+
+  const handleConfirmRename = () => {
+    if (editingId && editTitle.trim()) {
+      onRenameSession(editingId, editTitle.trim());
+    }
+    setEditingId(null);
+    setEditTitle("");
+  };
+
+  const handleCancelRename = () => {
+    setEditingId(null);
+    setEditTitle("");
+  };
+
+  if (collapsed) {
+    return (
+      <div className="sidebar sidebar--collapsed">
+        <button className="sidebar__toggle" onClick={onToggleCollapse} title={t("sidebar.expand")}>
+          ☰
+        </button>
+        <button className="sidebar__new-btn" onClick={onNewSession} title={t("sidebar.new")}>
+          ✚
+        </button>
+      </div>
+    );
+  }
+
+  return (
+    <div className="sidebar">
+      <div className="sidebar__header">
+        <button className="sidebar__new-btn sidebar__new-btn--full" onClick={onNewSession}>
+          ✚ {t("sidebar.new")}
+        </button>
+        <button className="sidebar__toggle" onClick={onToggleCollapse} title={t("sidebar.collapse")}>
+          ◀
+        </button>
+      </div>
+
+      <div className="sidebar__list">
+        {sessions.length === 0 ? (
+          <div className="sidebar__empty">{t("sidebar.empty")}</div>
+        ) : (
+          sessions.map((session) => (
+            <div
+              key={session.id}
+              className={`sidebar__item ${session.id === activeSessionId ? "sidebar__item--active" : ""}`}
+              onClick={() => onSelectSession(session.id)}
+            >
+              {editingId === session.id ? (
+                <div className="sidebar__edit" onClick={(e) => e.stopPropagation()}>
+                  <input
+                    className="sidebar__edit-input"
+                    value={editTitle}
+                    onChange={(e) => setEditTitle(e.target.value)}
+                    onKeyDown={(e) => {
+                      if (e.key === "Enter") handleConfirmRename();
+                      if (e.key === "Escape") handleCancelRename();
+                    }}
+                    autoFocus
+                  />
+                  <button className="sidebar__edit-btn" onClick={handleConfirmRename}>✓</button>
+                  <button className="sidebar__edit-btn" onClick={handleCancelRename}>✕</button>
+                </div>
+              ) : (
+                <>
+                  <div className="sidebar__item-content">
+                    <div className="sidebar__item-title">{session.title}</div>
+                    <div className="sidebar__item-meta">
+                      {session.messageCount > 0 && (
+                        <span>{session.messageCount}{t("sidebar.messages")}</span>
+                      )}
+                      <span>{formatRelativeTime(session.lastActiveAt)}</span>
+                    </div>
+                  </div>
+                  <div className="sidebar__item-actions">
+                    <button
+                      className="sidebar__action-btn"
+                      onClick={(e) => {
+                        e.stopPropagation();
+                        handleStartRename(session.id, session.title);
+                      }}
+                      title={t("sidebar.rename")}
+                    >
+                      ✏
+                    </button>
+                    <button
+                      className="sidebar__action-btn sidebar__action-btn--danger"
+                      onClick={(e) => {
+                        e.stopPropagation();
+                        onDeleteSession(session.id);
+                      }}
+                      title={t("sidebar.delete")}
+                    >
+                      🗑
+                    </button>
+                  </div>
+                </>
+              )}
+            </div>
+          ))
+        )}
+      </div>
+    </div>
+  );
+}

frontend/src/hooks/useSessionList.ts

@@ -0,0 +1,117 @@
+// ============================================================
+// useSessionList — 会话历史列表管理
+// 职责：会话 CRUD、消息持久化、切换会话
+// ============================================================
+
+import { useCallback, useEffect, useRef, useState } from "react";
+import { v4 as uuidv4 } from "uuid";
+import {
+  loadSessionSummaries,
+  saveSessionSummaries,
+  loadSessionMessages,
+  saveSessionMessages,
+  deleteSessionMessages,
+} from "../lib/storage";
+import type { ChatMessage, SessionSummary } from "../types";
+
+/** 截取预览文本 */
+function getPreview(text: string, maxLen = 50): string {
+  const clean = text.replace(/[\n\r]/g, " ").trim();
+  return clean.length > maxLen ? clean.slice(0, maxLen) + "…" : clean;
+}
+
+export function useSessionList() {
+  const [sessions, setSessions] = useState<SessionSummary[]>(() => loadSessionSummaries());
+  const [activeSessionId, setActiveSessionId] = useState<string | null>(null);
+  const sessionsRef = useRef(sessions);
+  useEffect(() => { sessionsRef.current = sessions; }, [sessions]);
+
+  /** 创建新会话 */
+  const createSession = useCallback((): string => {
+    const id = uuidv4();
+    const now = Date.now();
+    const summary: SessionSummary = {
+      id,
+      title: "新对话",
+      createdAt: now,
+      lastActiveAt: now,
+      messageCount: 0,
+      preview: "",
+    };
+    setSessions((prev) => [summary, ...prev]);
+    setActiveSessionId(id);
+    // 持久化
+    const all = [summary, ...sessionsRef.current];
+    saveSessionSummaries(all);
+    return id;
+  }, []);
+
+  /** 删除会话 */
+  const deleteSession = useCallback((id: string) => {
+    setSessions((prev) => prev.filter((s) => s.id !== id));
+    deleteSessionMessages(id);
+    const remaining = sessionsRef.current.filter((s) => s.id !== id);
+    saveSessionSummaries(remaining);
+    // 如果删除的是当前会话，清空 active
+    setActiveSessionId((prev) => (prev === id ? null : prev));
+  }, []);
+
+  /** 重命名会话 */
+  const renameSession = useCallback((id: string, title: string) => {
+    setSessions((prev) => prev.map((s) => (s.id === id ? { ...s, title } : s)));
+    const updated = sessionsRef.current.map((s) => (s.id === id ? { ...s, title } : s));
+    saveSessionSummaries(updated);
+  }, []);
+
+  /** 保存当前会话的消息历史 */
+  const saveCurrentSession = useCallback((messages: ChatMessage[]) => {
+    const id = sessionsRef.current.length > 0 ? sessionsRef.current[0].id : null;
+    // 找到 activeSessionId 对应的会话
+    // 这里不依赖 activeSessionId state，而是通过参数传入
+    return messages;
+  }, []);
+
+  /** 保存指定会话的消息并更新摘要 */
+  const persistSession = useCallback((sessionId: string, messages: ChatMessage[]) => {
+    if (!sessionId) return;
+    saveSessionMessages(sessionId, messages);
+    // 更新摘要
+    const firstUserMsg = messages.find((m) => m.role === "user");
+    const title = firstUserMsg ? getPreview(firstUserMsg.content, 20) : "新对话";
+    const lastMsg = messages[messages.length - 1];
+    const summary: Partial<SessionSummary> = {
+      title,
+      messageCount: messages.length,
+      lastActiveAt: lastMsg?.timestamp || Date.now(),
+      preview: lastMsg ? getPreview(lastMsg.content) : "",
+    };
+    setSessions((prev) => {
+      const updated = prev.map((s) => (s.id === sessionId ? { ...s, ...summary } : s));
+      saveSessionSummaries(updated);
+      return updated;
+    });
+  }, []);
+
+  /** 加载指定会话的消息历史 */
+  const loadMessages = useCallback((sessionId: string): ChatMessage[] => {
+    return loadSessionMessages(sessionId);
+  }, []);
+
+  /** 选择会话（返回需要加载的消息） */
+  const selectSession = useCallback((id: string): ChatMessage[] => {
+    setActiveSessionId(id);
+    return loadSessionMessages(id);
+  }, []);
+
+  return {
+    sessions,
+    activeSessionId,
+    setActiveSessionId,
+    createSession,
+    deleteSession,
+    renameSession,
+    persistSession,
+    loadMessages,
+    selectSession,
+  };
+}

frontend/src/hooks/useVisionSession.ts

@@ -458,6 +458,7 @@ export function useVisionSession() {
 
   return {
     messages,
+    setMessages,
     currentReply,
     isProcessing,
     isAudioPlaying,

frontend/src/lib/i18n/en-US.ts

@@ -81,6 +81,15 @@ export const enUS: TranslationMap = {
   "error.INTERNAL_ERROR": "Internal server error, please retry",
   "error.unknown": "Unknown error",
 
+  // Sidebar
+  "sidebar.new": "New Chat",
+  "sidebar.expand": "Expand sidebar",
+  "sidebar.collapse": "Collapse sidebar",
+  "sidebar.empty": "No chat history",
+  "sidebar.messages": " messages",
+  "sidebar.rename": "Rename",
+  "sidebar.delete": "Delete",
+
   // Device errors
   "error.vadInit": "VAD initialization failed",
   "error.cameraAccess": "Cannot access camera",

frontend/src/lib/i18n/ja-JP.ts

@@ -81,6 +81,15 @@ export const jaJP: TranslationMap = {
   "error.INTERNAL_ERROR": "サーバー内部エラー。再試行してください",
   "error.unknown": "不明なエラー",
 
+  // Sidebar
+  "sidebar.new": "新しいチャット",
+  "sidebar.expand": "サイドバーを展開",
+  "sidebar.collapse": "サイドバーを折りたたむ",
+  "sidebar.empty": "会話履歴がありません",
+  "sidebar.messages": "件のメッセージ",
+  "sidebar.rename": "名前を変更",
+  "sidebar.delete": "削除",
+
   // Device errors
   "error.vadInit": "VAD初期化に失敗しました",
   "error.cameraAccess": "カメラにアクセスできません",

frontend/src/lib/i18n/zh-CN.ts

@@ -81,6 +81,15 @@ export const zhCN: TranslationMap = {
   "error.INTERNAL_ERROR": "服务内部错误，请重试",
   "error.unknown": "未知错误",
 
+  // Sidebar
+  "sidebar.new": "新对话",
+  "sidebar.expand": "展开侧边栏",
+  "sidebar.collapse": "收起侧边栏",
+  "sidebar.empty": "暂无会话记录",
+  "sidebar.messages": "条消息",
+  "sidebar.rename": "重命名",
+  "sidebar.delete": "删除",
+
   // Device errors
   "error.vadInit": "VAD 初始化失败",
   "error.cameraAccess": "无法访问摄像头",

frontend/src/lib/storage.ts

@@ -3,7 +3,7 @@
 // 职责：会话配置持久化
 // ============================================================
 
-import type { SessionConfig, Theme } from "../types";
+import type { ChatMessage, SessionConfig, SessionSummary, Theme } from "../types";
 
 const CONFIG_KEY = "camtalk:config";
 const THEME_KEY = "camtalk:theme";
@@ -52,3 +52,51 @@ export function saveTheme(theme: Theme): void {
     localStorage.setItem(THEME_KEY, theme);
   } catch { /* ignore */ }
 }
+
+// ---- 会话历史存储 ----
+
+const SESSIONS_KEY = "camtalk:sessions";
+const SESSION_MSG_PREFIX = "camtalk:session:";
+
+/** 加载所有会话摘要（按 lastActiveAt 倒序） */
+export function loadSessionSummaries(): SessionSummary[] {
+  try {
+    const raw = localStorage.getItem(SESSIONS_KEY);
+    if (!raw) return [];
+    return (JSON.parse(raw) as SessionSummary[]).sort((a, b) => b.lastActiveAt - a.lastActiveAt);
+  } catch {
+    return [];
+  }
+}
+
+/** 保存会话摘要列表 */
+export function saveSessionSummaries(sessions: SessionSummary[]): void {
+  try {
+    localStorage.setItem(SESSIONS_KEY, JSON.stringify(sessions));
+  } catch { /* ignore */ }
+}
+
+/** 加载单个会话的消息历史 */
+export function loadSessionMessages(sessionId: string): ChatMessage[] {
+  try {
+    const raw = localStorage.getItem(SESSION_MSG_PREFIX + sessionId);
+    if (!raw) return [];
+    return JSON.parse(raw) as ChatMessage[];
+  } catch {
+    return [];
+  }
+}
+
+/** 保存单个会话的消息历史 */
+export function saveSessionMessages(sessionId: string, messages: ChatMessage[]): void {
+  try {
+    localStorage.setItem(SESSION_MSG_PREFIX + sessionId, JSON.stringify(messages));
+  } catch { /* ignore */ }
+}
+
+/** 删除单个会话的消息历史 */
+export function deleteSessionMessages(sessionId: string): void {
+  try {
+    localStorage.removeItem(SESSION_MSG_PREFIX + sessionId);
+  } catch { /* ignore */ }
+}

frontend/src/types/index.ts

@@ -19,6 +19,16 @@ export interface Session {
   config: SessionConfig;
 }
 
+/** 会话摘要（侧边栏列表用） */
+export interface SessionSummary {
+  id: string;
+  title: string;
+  createdAt: number;
+  lastActiveAt: number;
+  messageCount: number;
+  preview: string;
+}
+
 // ---- 聊天消息 ----
 
 export interface ChatMessage {