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

@@ -1,21 +1,27 @@
 // ============================================================
-// 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, useRef, useState } from "react";
+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 { loadTheme, saveTheme } from "./lib/storage";
+import { loadConfig, loadTheme, saveTheme } from "./lib/storage";
+import { I18nContext, parseLocale, t } from "./lib/i18n";
+import type { Locale } from "./lib/i18n";
 import type { Theme } from "./types";
 import "./App.css";
 
-function App() {
+/** 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
@@ -34,8 +40,21 @@ function App() {
     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,
@@ -88,28 +107,82 @@ function App() {
     return () => clearInterval(id);
   }, [isConnected]);
 
+  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 ---- */}
       <header className="header">
         <div className="header__left">
           <h1 className="header__title">CamTalk</h1>
-          <span className="header__subtitle">AI 视觉对话助手</span>
+          <span className="header__subtitle">{tr("app.title")}</span>
         </div>
         <div className="header__right">
-          {isConnected && (stats.queryCount > 0 || stats.totalTokens > 0) && (
+          {isConnected && stats.queryCount > 0 && (
             <span className="header__stats">
-              {stats.queryCount} 次请求 · {stats.totalTokens} tokens
+              {stats.queryCount} {tr("app.stats.requests")}
             </span>
           )}
           <span className={`badge badge--${connectionStatus}`}>
-            {isConnected ? "已连接" : connectionStatus === "connecting" ? "连接中..." : "未连接"}
+            {isConnected ? tr("status.connected") : connectionStatus === "connecting" ? tr("status.connecting") : tr("status.disconnected")}
           </span>
           <button
             className="btn-icon"
             onClick={() => setShowConfig((v) => !v)}
-            title="设置"
+            title={tr("settings.title")}
-            aria-label="设置"
+            aria-label={tr("settings.title")}
           >
             <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.8" strokeLinecap="round" strokeLinejoin="round">
               <circle cx="12" cy="12" r="3" />
@@ -129,9 +202,21 @@ function App() {
         />
       )}
 
-      {/* ---- 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} />
@@ -145,16 +230,16 @@ function App() {
               <div className="detail-badge">HD</div>
             )}
             {isObserving && (
-              <div className="observation-badge">👁️ 观察中</div>
+              <div className="observation-badge">{tr("video.observing")}</div>
             )}
             {isSpeaking && (
-              <div className="video-indicator">🎤 正在聆听...</div>
+              <div className="video-indicator">{tr("video.listening")}</div>
             )}
             {isAudioPlaying && config.ttsEnabled && (
-              <div className="video-indicator video-indicator--audio">🔊 正在播放...</div>
+              <div className="video-indicator video-indicator--audio">{tr("video.playing")}</div>
             )}
             {isConnected && !isVADReady && !vadError && (
-              <div className="video-indicator video-indicator--loading">正在初始化语音检测...</div>
+              <div className="video-indicator video-indicator--loading">{tr("video.initVad")}</div>
             )}
             {vadError && (
               <div className="video-indicator video-indicator--error">⚠️ {vadError}</div>
@@ -170,7 +255,7 @@ function App() {
                   <path d="M23 19a2 2 0 0 1-2 2H3a2 2 0 0 1-2-2V8a2 2 0 0 1 2-2h4l2-3h6l2 3h4a2 2 0 0 1 2 2z" />
                   <circle cx="12" cy="13" r="4" />
                 </svg>
-                <span>点击下方按钮开始对话</span>
+                <span>{tr("video.placeholder")}</span>
               </div>
             )}
             {isConnected && !isCameraOn && (
@@ -179,8 +264,8 @@ function App() {
                   <path d="M23 19a2 2 0 0 1-2 2H3a2 2 0 0 1-2-2V8a2 2 0 0 1 2-2h4l2-3h6l2 3h4a2 2 0 0 1 2 2z" />
                   <circle cx="12" cy="13" r="4" />
                 </svg>
-                <span>摄像头未开启</span>
+                <span>{tr("video.cameraOff")}</span>
-                <span className="video-placeholder__hint">可在右侧聊天框打字对话</span>
+                <span className="video-placeholder__hint">{tr("video.cameraOff.hint")}</span>
               </div>
             )}
           </div>
@@ -189,21 +274,21 @@ function App() {
           <div className="video-controls">
             {!isConnected ? (
               <button className="btn btn--primary btn--lg" onClick={startSession}>
-                {connectionStatus === "connecting" ? "连接中..." : "🎙️ 开始对话"}
+                {connectionStatus === "connecting" ? tr("controls.connecting") : tr("controls.startVideo")}
               </button>
             ) : (
               <div className="video-controls__row">
                 <button
                   className={`btn btn--ctrl ${isCameraOn ? "btn--ctrl-on" : "btn--ctrl-off"}`}
                   onClick={toggleCamera}
-                  title={isCameraOn ? "关闭摄像头" : "开启摄像头"}
+                  title={isCameraOn ? tr("controls.cameraOff") : tr("controls.cameraOn")}
                 >
                   📷
                 </button>
                 <button
                   className={`btn btn--ctrl ${isMicOn ? "btn--ctrl-on" : "btn--ctrl-off"} ${isSpeaking ? "btn--speaking" : ""}`}
                   onClick={toggleMic}
-                  title={isMicOn ? "关闭麦克风" : "开启麦克风"}
+                  title={isMicOn ? tr("controls.micOff") : tr("controls.micOn")}
                 >
                   🎤
                 </button>
@@ -211,15 +296,15 @@ function App() {
                   className={`btn ${mode === "observation" ? "btn--active" : "btn--secondary"}`}
                   onClick={toggleMode}
                 >
-                  {mode === "observation" ? "👁️ 观察中" : "👁️ 观察模式"}
+                  {mode === "observation" ? tr("controls.observing") : tr("controls.observation")}
                 </button>
                 {isProcessing && (
                   <button className="btn btn--warning" onClick={interrupt}>
-                    ⏹ 打断
+                    {tr("controls.interrupt")}
                   </button>
                 )}
                 <button className="btn btn--danger" onClick={stopSession}>
-                  结束对话
+                  {tr("controls.stop")}
                 </button>
               </div>
             )}
@@ -229,15 +314,15 @@ function App() {
         {/* 右侧：聊天面板 */}
         <div className="chat-panel-wrapper">
           <div className="chat-panel-header">
-            <span>对话</span>
+            <span>{tr("chat.title")}</span>
             {isConnected && mode === "observation" && (
-              <span className="chat-panel-header__mode">观察模式</span>
+              <span className="chat-panel-header__mode">{tr("chat.mode.observation")}</span>
             )}
           </div>
           <div className="chat-panel-body">
             {connectionStatus === "disconnected" && messages.length > 0 && (
               <div className="system-message system-message--warning">
-                连接已断开，正在重连...
+                {tr("chat.reconnecting")}
               </div>
             )}
             <ChatPanel
@@ -255,4 +340,30 @@ function App() {
   );
 }
 
+function App() {
+  const [locale, setLocale] = useState<Locale>(() => parseLocale(loadConfig().language));
+
+  const i18nValue = useMemo(() => ({
+    locale,
+    t: (key: string) => t(key, locale),
+  }), [locale]);
+
+  // 监听配置变化以更新 locale
+  useEffect(() => {
+    const handler = () => {
+      const cfg = loadConfig();
+      setLocale(parseLocale(cfg.language));
+    };
+    // 自定义事件，由 saveConfig 触发
+    window.addEventListener("camtalk-config-changed", handler);
+    return () => window.removeEventListener("camtalk-config-changed", handler);
+  }, []);
+
+  return (
+    <I18nContext.Provider value={i18nValue}>
+      <AppContent />
+    </I18nContext.Provider>
+  );
+}
+
 export default App;

frontend/src/components/CameraManager/index.tsx

@@ -4,6 +4,7 @@
 // ============================================================
 
 import { useCallback, useRef, useState } from "react";
+import { useI18n } from "../../lib/i18n";
 
 export interface CameraManagerHandle {
   /** 获取当前视频轨道 */
@@ -13,6 +14,7 @@ export interface CameraManagerHandle {
 }
 
 export function useCamera() {
+  const { t } = useI18n();
   const videoRef = useRef<HTMLVideoElement>(null);
   const [stream, setStream] = useState<MediaStream | null>(null);
   const [error, setError] = useState<string | null>(null);
@@ -29,7 +31,7 @@ export function useCamera() {
       }
       setError(null);
     } catch (err) {
-      const message = err instanceof Error ? err.message : "无法访问摄像头";
+      const message = err instanceof Error ? err.message : t("error.cameraAccess");
       setError(message);
       console.error("[Camera] 获取摄像头失败:", err);
     }

frontend/src/components/ChatPanel/index.tsx

@@ -4,6 +4,7 @@
 // ============================================================
 
 import { useEffect, useRef, useState } from "react";
+import { useI18n } from "../../lib/i18n";
 import type { ChatMessage } from "../../types";
 import type { ConnectionStatus } from "../../lib/websocket";
 
@@ -19,6 +20,7 @@ export function ChatPanel({ messages, currentReply, connectionStatus, onSendText
   const containerRef = useRef<HTMLDivElement>(null);
   const isAutoScroll = useRef(true);
   const [inputText, setInputText] = useState("");
+  const { t } = useI18n();
 
   const isConnected = connectionStatus === "connected";
 
@@ -51,17 +53,6 @@ export function ChatPanel({ messages, currentReply, connectionStatus, onSendText
     setInputText("");
   };
 
-  // 未连接时的空状态
-  if (!isConnected) {
-    return (
-      <div className="chat-panel chat-panel--empty">
-        <span className="chat-panel--empty-icon">💬</span>
-        <p>点击下方按钮开始对话</p>
-        <span className="chat-panel--empty-hint">连接后可打字或语音与 AI 交互</span>
-      </div>
-    );
-  }
-
   return (
     <div className="chat-panel">
       <div className="chat-panel__messages" ref={containerRef}>
@@ -69,15 +60,15 @@ export function ChatPanel({ messages, currentReply, connectionStatus, onSendText
         {messages.length === 0 && !currentReply && (
           <div className="chat-panel__welcome">
             <span className="chat-panel__welcome-icon">💬</span>
-            <p>在下方输入文字开始对话</p>
+            <p>{isConnected ? t("chat.welcome.prompt") : t("chat.empty.prompt")}</p>
-            <span className="chat-panel__welcome-hint">也可以开启麦克风用语音对话</span>
+            <span className="chat-panel__welcome-hint">{isConnected ? t("chat.welcome.hint") : t("chat.empty.hint")}</span>
           </div>
         )}
 
         {messages.map((msg, index) => (
           <div key={index} className={`chat-message chat-message--${msg.role}`}>
             <div className="chat-message__role">
-              {msg.role === "user" ? "你" : "AI"}
+              {msg.role === "user" ? t("chat.userLabel") : "AI"}
             </div>
             <div className="chat-message__content">{msg.content}</div>
             {msg.role === "assistant" && msg.tokensUsed !== undefined && (
@@ -104,21 +95,22 @@ export function ChatPanel({ messages, currentReply, connectionStatus, onSendText
         <div ref={bottomRef} />
       </div>
 
-      {/* 文本输入框 - 连接后始终显示 */}
+      {/* 文本输入框 - 始终显示 */}
       {onSendText && (
         <form className="chat-input" onSubmit={handleSubmit}>
           <input
             type="text"
             className="chat-input__field"
-            placeholder="输入文字对话..."
+            placeholder={t("chat.input.placeholder")}
             value={inputText}
             onChange={(e) => setInputText(e.target.value)}
+            disabled={connectionStatus === "connecting"}
           />
           <button
             type="submit"
             className="chat-input__send"
-            disabled={!inputText.trim()}
+            disabled={!inputText.trim() || connectionStatus === "connecting"}
-            title="发送"
+            title={t("chat.send")}
           >
             ➤
           </button>

frontend/src/components/ConfigPanel/index.tsx

@@ -3,6 +3,7 @@
 // 职责：主题切换、TTS 开关、detail level 切换、语言选择
 // ============================================================
 
+import { useI18n } from "../../lib/i18n";
 import type { SessionConfig, Theme } from "../../types";
 
 interface ConfigPanelProps {
@@ -14,40 +15,42 @@ interface ConfigPanelProps {
 }
 
 export function ConfigPanel({ config, theme, onUpdate, onThemeChange, onClose }: ConfigPanelProps) {
+  const { t } = useI18n();
+
   return (
     <div className="drawer-overlay" onClick={onClose}>
       <div className="drawer" onClick={(e) => e.stopPropagation()}>
         <div className="drawer__header">
-          <span className="drawer__title">设置</span>
+          <span className="drawer__title">{t("settings.title")}</span>
           <button className="drawer__close" onClick={onClose}>✕</button>
         </div>
 
         <div className="drawer__body">
           <div className="config-group">
-            <div className="config-group__title">外观</div>
+            <div className="config-group__title">{t("settings.appearance")}</div>
 
             <label className="config-row">
               <div className="config-row__info">
-                <span className="config-row__label">主题</span>
+                <span className="config-row__label">{t("settings.theme")}</span>
-                <span className="config-row__desc">切换明暗主题</span>
+                <span className="config-row__desc">{t("settings.theme.desc")}</span>
               </div>
               <select
                 value={theme}
                 onChange={(e) => onThemeChange(e.target.value as Theme)}
               >
-                <option value="dark">深色</option>
+                <option value="dark">{t("settings.theme.dark")}</option>
-                <option value="light">浅色</option>
+                <option value="light">{t("settings.theme.light")}</option>
               </select>
             </label>
           </div>
 
           <div className="config-group">
-            <div className="config-group__title">会话</div>
+            <div className="config-group__title">{t("settings.session")}</div>
 
             <label className="config-row">
               <div className="config-row__info">
-                <span className="config-row__label">语音回答</span>
+                <span className="config-row__label">{t("settings.tts")}</span>
-                <span className="config-row__desc">AI 回答时同步播放语音</span>
+                <span className="config-row__desc">{t("settings.tts.desc")}</span>
               </div>
               <input
                 type="checkbox"
@@ -58,22 +61,22 @@ export function ConfigPanel({ config, theme, onUpdate, onThemeChange, onClose }:
 
             <label className="config-row">
               <div className="config-row__info">
-                <span className="config-row__label">图像精度</span>
+                <span className="config-row__label">{t("settings.detail")}</span>
-                <span className="config-row__desc">高精度适合识别文字，低精度省流量</span>
+                <span className="config-row__desc">{t("settings.detail.desc")}</span>
               </div>
               <select
                 value={config.detailLevel}
                 onChange={(e) => onUpdate({ detailLevel: e.target.value as "low" | "high" })}
               >
-                <option value="low">低</option>
+                <option value="low">{t("settings.detail.low")}</option>
-                <option value="high">高</option>
+                <option value="high">{t("settings.detail.high")}</option>
               </select>
             </label>
 
             <label className="config-row">
               <div className="config-row__info">
-                <span className="config-row__label">语言</span>
+                <span className="config-row__label">{t("settings.language")}</span>
-                <span className="config-row__desc">交互语言偏好</span>
+                <span className="config-row__desc">{t("settings.language.desc")}</span>
               </div>
               <select
                 value={config.language}

frontend/src/components/EdgeProcessor/index.tsx

@@ -6,6 +6,7 @@
 
 import { useCallback, useEffect, useRef, useState } from "react";
 import { MicVAD } from "@ricky0123/vad-web";
+import { useI18n } from "../../lib/i18n";
 
 export interface VADOptions {
   /** 语音结束回调，携带录音 Float32Array（16kHz） */
@@ -21,6 +22,7 @@ export interface VADOptions {
  * 基于 @ricky0123/vad-web 的 MicVAD，检测用户说话并回调
  */
 export function useVAD(options?: VADOptions) {
+  const { t } = useI18n();
   const [isSpeaking, setIsSpeaking] = useState(false);
   const [isReady, setIsReady] = useState(false);
   const [error, setError] = useState<string | null>(null);
@@ -79,7 +81,7 @@ export function useVAD(options?: VADOptions) {
       setIsReady(true);
       setError(null);
     } catch (err) {
-      const message = err instanceof Error ? err.message : "VAD 初始化失败";
+      const message = err instanceof Error ? err.message : t("error.vadInit");
       setError(message);
       console.error("[VAD] 初始化失败:", err);
     }

frontend/src/components/MicManager/index.tsx

@@ -4,8 +4,10 @@
 // ============================================================
 
 import { useCallback, useRef, useState } from "react";
+import { useI18n } from "../../lib/i18n";
 
 export function useMicrophone() {
+  const { t } = useI18n();
   const [stream, setStream] = useState<MediaStream | null>(null);
   const [error, setError] = useState<string | null>(null);
   const audioContextRef = useRef<AudioContext | null>(null);
@@ -25,7 +27,7 @@ export function useMicrophone() {
       setError(null);
       return mediaStream;
     } catch (err) {
-      const message = err instanceof Error ? err.message : "无法访问麦克风";
+      const message = err instanceof Error ? err.message : t("error.micAccess");
       setError(message);
       console.error("[Mic] 获取麦克风失败:", err);
       return null;

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/components/VideoPreview/index.tsx

@@ -4,6 +4,7 @@
 // ============================================================
 
 import { forwardRef } from "react";
+import { useI18n } from "../../lib/i18n";
 
 interface VideoPreviewProps {
   isStreaming: boolean;
@@ -11,6 +12,8 @@ interface VideoPreviewProps {
 
 export const VideoPreview = forwardRef<HTMLVideoElement, VideoPreviewProps>(
   function VideoPreview({ isStreaming }, ref) {
+    const { t } = useI18n();
+
     return (
       <div className="video-preview">
         <video
@@ -22,7 +25,7 @@ export const VideoPreview = forwardRef<HTMLVideoElement, VideoPreviewProps>(
         />
         {!isStreaming && (
           <div className="video-preview__placeholder">
-            摄像头未开启
+            {t("video.cameraOff")}
           </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

@@ -12,6 +12,7 @@ import { getErrorMessage } from "../lib/errors";
 import { TTSPlayer } from "../lib/ttsPlayer";
 import { showToast } from "../lib/toast";
 import { loadConfig, saveConfig } from "../lib/storage";
+import { useI18n } from "../lib/i18n";
 import { useCamera } from "../components/CameraManager";
 import { useMicrophone } from "../components/MicManager";
 import { useVAD, sampleFrame, compareFrames } from "../components/EdgeProcessor";
@@ -29,6 +30,7 @@ export interface SessionStats {
 }
 
 export function useVisionSession() {
+  const { t } = useI18n();
   const [messages, setMessages] = useState<ChatMessage[]>([]);
   const [currentReply, setCurrentReply] = useState<string>("");
   const [isProcessing, setIsProcessing] = useState(false);
@@ -45,6 +47,9 @@ export function useVisionSession() {
   // 对话历史（role + content），用于多轮上下文
   const historyRef = useRef<Array<{ role: string; content: string }>>([]);
 
+  // 待发消息队列（未连接时暂存，连接后自动发送）
+  const pendingMessagesRef = useRef<Array<{ text: string; requestId: string }>>([]);
+
   // TTS 播放器
   const ttsPlayerRef = useRef<TTSPlayer | null>(null);
   const getTTSPlayer = useCallback(() => {
@@ -66,6 +71,12 @@ export function useVisionSession() {
     isProcessingRef.current = isProcessing;
   }, [isProcessing]);
 
+  // 用 ref 跟踪连接状态，避免回调闭包问题
+  const statusRef = useRef(status);
+  useEffect(() => {
+    statusRef.current = status;
+  }, [status]);
+
   // 观察模式：画面变化时自动发送 query
   const { isObserving, startObserving, stopObserving } = useObservationMode({
     onChange: useCallback(
@@ -84,7 +95,7 @@ export function useVisionSession() {
           ...prev,
           {
             role: "user",
-            content: "👁️ 画面变化检测",
+            content: t("session.changeDetected"),
             timestamp: Date.now(),
           },
         ]);
@@ -108,7 +119,7 @@ export function useVisionSession() {
     });
   }, [videoRef, captureFrame, startObserving, stopObserving]);
 
-  // WebSocket 连接成功后发送 config
+  // WebSocket 连接成功后发送 config + flush 待发消息
   useEffect(() => {
     if (status === "connected") {
       send({
@@ -119,6 +130,27 @@ export function useVisionSession() {
           language: config.language,
         },
       });
+
+      // flush 待发消息队列
+      const pending = pendingMessagesRef.current;
+      pendingMessagesRef.current = [];
+      for (const msg of pending) {
+        const frame = captureFrame();
+        send({
+          type: "query",
+          request_id: msg.requestId,
+          image: frame ? dataUrlToBase64(frame) : "",
+          audio: "",
+          text: msg.text,
+        });
+        setStats((prev) => ({ ...prev, queryCount: prev.queryCount + 1 }));
+        setMessages((prev) => [
+          ...prev,
+          { role: "user", content: msg.text, timestamp: Date.now() },
+        ]);
+        historyRef.current.push({ role: "user", content: msg.text });
+        setIsProcessing(true);
+      }
     }
   }, [status]); // eslint-disable-line react-hooks/exhaustive-deps -- 仅在连接状态变化时发送
 
@@ -199,7 +231,7 @@ export function useVisionSession() {
         // 添加用户消息（STT 流式结果会逐步更新文本）
         setMessages((prev) => [
           ...prev,
-          { role: "user", content: "（语音识别中...）", timestamp: Date.now() },
+          { role: "user", content: t("session.recognizing"), timestamp: Date.now() },
         ]);
         setIsProcessing(true);
       },
@@ -219,7 +251,7 @@ export function useVisionSession() {
             if (lastUserIdx >= 0) {
               updated[lastUserIdx] = {
                 ...updated[lastUserIdx],
-                content: msg.text || "（未识别到语音）",
+                content: msg.text || t("session.noSpeech"),
               };
             }
             return updated;
@@ -271,7 +303,7 @@ export function useVisionSession() {
 
         case "error":
           console.error("[Session] 服务端错误:", msg.code, msg.message);
-          showToast(getErrorMessage(msg.code), "error");
+          showToast(getErrorMessage(msg.code, t), "error");
           setIsProcessing(false);
           break;
       }
@@ -280,10 +312,13 @@ export function useVisionSession() {
     return unsub;
   }, [getTTSPlayer]);
 
-  /** 启动会话 */
+  /** 启动视频通话（摄像头 + 麦克风 + VAD） */
   const startSession = useCallback(async () => {
-    // 1. 连接 WebSocket（必须）
+    // 1. 确保 WebSocket 已连接
-    connect();
+    if (statusRef.current !== "connected") {
+      connect();
+      // 等待连接完成（通过 status 变化触发后续流程，这里直接继续）
+    }
 
     // 2. 尝试获取摄像头（可选）
     try {
@@ -359,7 +394,7 @@ export function useVisionSession() {
     setIsAudioPlaying(false);
     // 将未完成的流式内容保存为最终消息
     if (currentReply) {
-      const interrupted = currentReply + "（已打断）";
+      const interrupted = currentReply + t("session.interrupted");
       historyRef.current.push({ role: "assistant", content: interrupted });
       setMessages((prev) => [
         ...prev,
@@ -379,10 +414,23 @@ export function useVisionSession() {
       ttsPlayerRef.current?.stop();
       setIsAudioPlaying(false);
 
-      // 捕获当前摄像头画面
-      const frame = captureFrame();
-
       const requestId = uuidv4();
+
+      // 未连接时：自动连接，消息加入待发队列
+      if (statusRef.current !== "connected") {
+        pendingMessagesRef.current.push({ text: text.trim(), requestId });
+        // 添加用户消息到 UI（立即反馈）
+        setMessages((prev) => [
+          ...prev,
+          { role: "user", content: text.trim(), timestamp: Date.now() }],
+        );
+        // 自动连接 WebSocket
+        connect();
+        return;
+      }
+
+      // 已连接：直接发送
+      const frame = captureFrame();
       send({
         type: "query",
         request_id: requestId,
@@ -405,11 +453,12 @@ export function useVisionSession() {
 
       setIsProcessing(true);
     },
-    [captureFrame, send],
+    [captureFrame, send, connect],
   );
 
   return {
     messages,
+    setMessages,
     currentReply,
     isProcessing,
     isAudioPlaying,

frontend/src/lib/errors.ts

@@ -5,20 +5,13 @@
 
 import type { ErrorCode } from "../types";
 
-const ERROR_MESSAGES: Record<ErrorCode, string> = {
+/** 将错误码转为用户友好文案（需要传入翻译函数） */
-  INVALID_MESSAGE: "消息格式异常，请重试",
+export function getErrorMessage(code: string, translate: (key: string) => string): string {
-  SESSION_NOT_FOUND: "会话已过期，请重新连接",
+  const key = `error.${code}`;
-  RATE_LIMITED: "请求太频繁，请稍后再试",
+  const translated = translate(key);
-  IMAGE_TOO_LARGE: "图像过大，请降低分辨率",
+  // 如果翻译函数返回 key 本身（未找到翻译），用 fallback
-  AUDIO_TOO_SHORT: "语音太短，请再说一句",
+  if (translated === key) {
-  LLM_TIMEOUT: "AI 响应超时，请重试",
+    return translate("error.unknown") + `: ${code}`;
-  LLM_ERROR: "AI 服务异常，请稍后重试",
+  }
-  STT_ERROR: "语音识别失败，请重试",
+  return translated;
-  TTS_ERROR: "语音合成失败",
-  INTERNAL_ERROR: "服务内部错误，请重试",
-};
-
-/** 将错误码转为用户友好文案 */
-export function getErrorMessage(code: string): string {
-  return ERROR_MESSAGES[code as ErrorCode] ?? `未知错误: ${code}`;
 }

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

@@ -0,0 +1,97 @@
+import type { TranslationMap } from "./index";
+
+export const enUS: TranslationMap = {
+  // App header
+  "app.title": "AI Vision Assistant",
+  "app.stats.requests": "requests",
+
+  // Connection status
+  "status.connected": "Connected",
+  "status.connecting": "Connecting...",
+  "status.disconnected": "Disconnected",
+
+  // Settings
+  "settings.title": "Settings",
+  "settings.appearance": "Appearance",
+  "settings.theme": "Theme",
+  "settings.theme.desc": "Switch between light and dark theme",
+  "settings.theme.dark": "Dark",
+  "settings.theme.light": "Light",
+  "settings.session": "Session",
+  "settings.tts": "Voice Response",
+  "settings.tts.desc": "Play voice along with AI response",
+  "settings.detail": "Image Quality",
+  "settings.detail.desc": "High quality for text recognition, low saves bandwidth",
+  "settings.detail.low": "Low",
+  "settings.detail.high": "High",
+  "settings.language": "Language",
+  "settings.language.desc": "Interaction language preference",
+
+  // Video indicators
+  "video.observing": "👁️ Observing",
+  "video.listening": "🎤 Listening...",
+  "video.playing": "🔊 Playing...",
+  "video.initVad": "Initializing voice detection...",
+  "video.clickToStart": "Click the button below to start",
+  "video.placeholder": "Type in the chat panel to start",
+  "video.cameraOff": "Camera is off",
+  "video.cameraOff.hint": "You can type in the chat panel",
+
+  // Controls
+  "controls.connecting": "Connecting...",
+  "controls.start": "🎙️ Start Session",
+  "controls.startVideo": "🎙️ Start Video Call",
+  "controls.cameraOff": "Turn off camera",
+  "controls.cameraOn": "Turn on camera",
+  "controls.micOff": "Turn off microphone",
+  "controls.micOn": "Turn on microphone",
+  "controls.observing": "👁️ Observing",
+  "controls.observation": "👁️ Observe",
+  "controls.interrupt": "⏹ Interrupt",
+  "controls.stop": "End Session",
+
+  // Chat panel
+  "chat.title": "Chat",
+  "chat.mode.observation": "Observing",
+  "chat.reconnecting": "Connection lost, reconnecting...",
+  "chat.empty.prompt": "Type below to start chatting",
+  "chat.empty.hint": "Type to chat with AI, or click the button on the left to start video",
+  "chat.welcome.prompt": "Type below to start chatting",
+  "chat.welcome.hint": "Or enable microphone for voice chat",
+  "chat.userLabel": "You",
+  "chat.input.placeholder": "Type a message...",
+  "chat.send": "Send",
+
+  // Session messages
+  "session.changeDetected": "👁️ Scene change detected",
+  "session.recognizing": "(Recognizing speech...)",
+  "session.noSpeech": "(No speech detected)",
+  "session.interrupted": "(Interrupted)",
+
+  // Errors
+  "error.INVALID_MESSAGE": "Invalid message format, please retry",
+  "error.SESSION_NOT_FOUND": "Session expired, please reconnect",
+  "error.RATE_LIMITED": "Too many requests, please try again later",
+  "error.IMAGE_TOO_LARGE": "Image too large, please reduce resolution",
+  "error.AUDIO_TOO_SHORT": "Audio too short, please try again",
+  "error.LLM_TIMEOUT": "AI response timed out, please retry",
+  "error.LLM_ERROR": "AI service error, please try again later",
+  "error.STT_ERROR": "Speech recognition failed, please retry",
+  "error.TTS_ERROR": "Voice synthesis failed",
+  "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",
+  "error.micAccess": "Cannot access microphone",
+};

frontend/src/lib/i18n/index.ts

@@ -0,0 +1,47 @@
+// ============================================================
+// i18n — 轻量国际化模块
+// 职责：提供翻译函数和 React Context，根据 locale 返回对应语言文本
+// ============================================================
+
+import { createContext, useContext } from "react";
+import { zhCN } from "./zh-CN";
+import { enUS } from "./en-US";
+import { jaJP } from "./ja-JP";
+
+export type Locale = "zh-CN" | "en-US" | "ja-JP";
+
+export type TranslationMap = Record<string, string>;
+
+const translations: Record<Locale, TranslationMap> = {
+  "zh-CN": zhCN,
+  "en-US": enUS,
+  "ja-JP": jaJP,
+};
+
+/** 翻译函数：根据 key 和 locale 返回翻译文本 */
+export function t(key: string, locale: Locale): string {
+  return translations[locale]?.[key] ?? translations["zh-CN"][key] ?? key;
+}
+
+/** 从 config.language 值解析为合法 Locale */
+export function parseLocale(lang: string): Locale {
+  if (lang === "en-US" || lang === "ja-JP") return lang;
+  return "zh-CN";
+}
+
+// ---- React Context ----
+
+export interface I18nContextValue {
+  locale: Locale;
+  t: (key: string) => string;
+}
+
+export const I18nContext = createContext<I18nContextValue>({
+  locale: "zh-CN",
+  t: (key) => t(key, "zh-CN"),
+});
+
+/** 组件内获取 i18n 的便捷 Hook */
+export function useI18n() {
+  return useContext(I18nContext);
+}

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

@@ -0,0 +1,97 @@
+import type { TranslationMap } from "./index";
+
+export const jaJP: TranslationMap = {
+  // App header
+  "app.title": "AI ビジョンアシスタント",
+  "app.stats.requests": "リクエスト",
+
+  // Connection status
+  "status.connected": "接続済み",
+  "status.connecting": "接続中...",
+  "status.disconnected": "未接続",
+
+  // Settings
+  "settings.title": "設定",
+  "settings.appearance": "外観",
+  "settings.theme": "テーマ",
+  "settings.theme.desc": "ライト/ダークテーマを切り替え",
+  "settings.theme.dark": "ダーク",
+  "settings.theme.light": "ライト",
+  "settings.session": "セッション",
+  "settings.tts": "音声応答",
+  "settings.tts.desc": "AI応答と同時に音声を再生",
+  "settings.detail": "画像品質",
+  "settings.detail.desc": "高品質は文字認識に最適、低品質は帯域節約",
+  "settings.detail.low": "低",
+  "settings.detail.high": "高",
+  "settings.language": "言語",
+  "settings.language.desc": "インタラクション言語の設定",
+
+  // Video indicators
+  "video.observing": "👁️ 観察中",
+  "video.listening": "🎤 聞き取り中...",
+  "video.playing": "🔊 再生中...",
+  "video.initVad": "音声検出を初期化中...",
+  "video.clickToStart": "下のボタンをクリックして開始",
+  "video.placeholder": "右側のチャットに入力して開始",
+  "video.cameraOff": "カメラがオフです",
+  "video.cameraOff.hint": "右側のチャットでテキスト対話ができます",
+
+  // Controls
+  "controls.connecting": "接続中...",
+  "controls.start": "🎙️ 対話を開始",
+  "controls.startVideo": "🎙️ ビデオ通話を開始",
+  "controls.cameraOff": "カメラをオフ",
+  "controls.cameraOn": "カメラをオン",
+  "controls.micOff": "マイクをオフ",
+  "controls.micOn": "マイクをオン",
+  "controls.observing": "👁️ 観察中",
+  "controls.observation": "👁️ 観察モード",
+  "controls.interrupt": "⏹ 中断",
+  "controls.stop": "対話を終了",
+
+  // Chat panel
+  "chat.title": "チャット",
+  "chat.mode.observation": "観察モード",
+  "chat.reconnecting": "接続が切断されました。再接続中...",
+  "chat.empty.prompt": "下にテキストを入力して対話を開始",
+  "chat.empty.hint": "テキストでAIと対話、または左のボタンでビデオ通話を開始",
+  "chat.welcome.prompt": "下にテキストを入力して対話を開始",
+  "chat.welcome.hint": "マイクを有効にして音声対話もできます",
+  "chat.userLabel": "あなた",
+  "chat.input.placeholder": "メッセージを入力...",
+  "chat.send": "送信",
+
+  // Session messages
+  "session.changeDetected": "👁️ シーン変化を検出",
+  "session.recognizing": "（音声認識中...）",
+  "session.noSpeech": "（音声が検出されませんでした）",
+  "session.interrupted": "（中断済み）",
+
+  // Errors
+  "error.INVALID_MESSAGE": "メッセージ形式が無効です。再試行してください",
+  "error.SESSION_NOT_FOUND": "セッションが期限切れです。再接続してください",
+  "error.RATE_LIMITED": "リクエストが多すぎます。しばらく待ってから再試行してください",
+  "error.IMAGE_TOO_LARGE": "画像が大きすぎます。解像度を下げてください",
+  "error.AUDIO_TOO_SHORT": "音声が短すぎます。もう一度お試しください",
+  "error.LLM_TIMEOUT": "AI応答がタイムアウトしました。再試行してください",
+  "error.LLM_ERROR": "AIサービスエラー。しばらく待ってから再試行してください",
+  "error.STT_ERROR": "音声認識に失敗しました。再試行してください",
+  "error.TTS_ERROR": "音声合成に失敗しました",
+  "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",
+  "error.micAccess": "マイクにアクセスできません",
+};

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

@@ -0,0 +1,97 @@
+import type { TranslationMap } from "./index";
+
+export const zhCN: TranslationMap = {
+  // App header
+  "app.title": "AI 视觉对话助手",
+  "app.stats.requests": "次请求",
+
+  // Connection status
+  "status.connected": "已连接",
+  "status.connecting": "连接中...",
+  "status.disconnected": "未连接",
+
+  // Settings
+  "settings.title": "设置",
+  "settings.appearance": "外观",
+  "settings.theme": "主题",
+  "settings.theme.desc": "切换明暗主题",
+  "settings.theme.dark": "深色",
+  "settings.theme.light": "浅色",
+  "settings.session": "会话",
+  "settings.tts": "语音回答",
+  "settings.tts.desc": "AI 回答时同步播放语音",
+  "settings.detail": "图像精度",
+  "settings.detail.desc": "高精度适合识别文字，低精度省流量",
+  "settings.detail.low": "低",
+  "settings.detail.high": "高",
+  "settings.language": "语言",
+  "settings.language.desc": "交互语言偏好",
+
+  // Video indicators
+  "video.observing": "👁️ 观察中",
+  "video.listening": "🎤 正在聆听...",
+  "video.playing": "🔊 正在播放...",
+  "video.initVad": "正在初始化语音检测...",
+  "video.clickToStart": "点击下方按钮开始对话",
+  "video.placeholder": "在右侧聊天框输入即可开始对话",
+  "video.cameraOff": "摄像头未开启",
+  "video.cameraOff.hint": "可在右侧聊天框打字对话",
+
+  // Controls
+  "controls.connecting": "连接中...",
+  "controls.start": "🎙️ 开始对话",
+  "controls.startVideo": "🎙️ 开始视频通话",
+  "controls.cameraOff": "关闭摄像头",
+  "controls.cameraOn": "开启摄像头",
+  "controls.micOff": "关闭麦克风",
+  "controls.micOn": "开启麦克风",
+  "controls.observing": "👁️ 观察中",
+  "controls.observation": "👁️ 观察模式",
+  "controls.interrupt": "⏹ 打断",
+  "controls.stop": "结束对话",
+
+  // Chat panel
+  "chat.title": "对话",
+  "chat.mode.observation": "观察模式",
+  "chat.reconnecting": "连接已断开，正在重连...",
+  "chat.empty.prompt": "在下方输入文字开始对话",
+  "chat.empty.hint": "输入文字即可与 AI 交互，也可点击左侧按钮开启视频",
+  "chat.welcome.prompt": "在下方输入文字开始对话",
+  "chat.welcome.hint": "也可以开启麦克风用语音对话",
+  "chat.userLabel": "你",
+  "chat.input.placeholder": "输入文字对话...",
+  "chat.send": "发送",
+
+  // Session messages
+  "session.changeDetected": "👁️ 画面变化检测",
+  "session.recognizing": "（语音识别中...）",
+  "session.noSpeech": "（未识别到语音）",
+  "session.interrupted": "（已打断）",
+
+  // Errors
+  "error.INVALID_MESSAGE": "消息格式异常，请重试",
+  "error.SESSION_NOT_FOUND": "会话已过期，请重新连接",
+  "error.RATE_LIMITED": "请求太频繁，请稍后再试",
+  "error.IMAGE_TOO_LARGE": "图像过大，请降低分辨率",
+  "error.AUDIO_TOO_SHORT": "语音太短，请再说一句",
+  "error.LLM_TIMEOUT": "AI 响应超时，请重试",
+  "error.LLM_ERROR": "AI 服务异常，请稍后重试",
+  "error.STT_ERROR": "语音识别失败，请重试",
+  "error.TTS_ERROR": "语音合成失败",
+  "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",
+  "error.micAccess": "无法访问麦克风",
+};

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";
@@ -30,6 +30,8 @@ export function loadConfig(): SessionConfig {
 export function saveConfig(config: SessionConfig): void {
   try {
     localStorage.setItem(CONFIG_KEY, JSON.stringify(config));
+    // 派发自定义事件，通知 App 更新 locale
+    window.dispatchEvent(new CustomEvent("camtalk-config-changed"));
   } catch {
     // localStorage 不可用时静默失败
   }
@@ -50,3 +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 {