fix(web): load most recent session instead of creating new chat

When clicking on the chat page, now loads the most recent conversation
instead of always creating a new empty chat. This improves UX by showing
users their last conversation context.

Changes:
- Modified usePicoChat hook to load recent session on mount
- Added isLoadingSession state to show loading indicator
- Added 'loading' translation key for both en and zh

Fixes #1373

web/frontend/src/components/chat/chat-page.tsx

@@ -26,6 +26,7 @@ export function ChatPage() {
     messages,
     isTyping,
     activeSessionId,
+    isLoadingSession,
     sendMessage,
     switchSession,
     newChat,
@@ -122,13 +123,19 @@ export function ChatPage() {
         className="min-h-0 flex-1 overflow-y-auto px-4 py-6 md:px-8 lg:px-24 xl:px-48"
       >
         <div className="mx-auto flex w-full max-w-250 flex-col gap-8 pb-8">
-          {messages.length === 0 && !isTyping && (
+          {isLoadingSession ? (
+            <div className="flex flex-1 items-center justify-center py-20">
+              <div className="text-muted-foreground animate-pulse">
+                {t("chat.loading")}
+              </div>
+            </div>
+          ) : messages.length === 0 && !isTyping ? (
             <ChatEmptyState
               hasConfiguredModels={hasConfiguredModels}
               defaultModelName={defaultModelName}
               isConnected={isConnected}
             />
-          )}
+          ) : null}
 
           {messages.map((msg) => (
             <div key={msg.id} className="flex w-full">

web/frontend/src/hooks/use-pico-chat.ts

@@ -108,8 +108,8 @@ export function usePicoChat() {
   const [connectionState, setConnectionState] =
     useState<ConnectionState>("disconnected")
   const [isTyping, setIsTyping] = useState(false)
-  const [activeSessionId, setActiveSessionId] =
+  const [activeSessionId, setActiveSessionId] = useState<string>("")
-    useState<string>(generateSessionId)
+  const [isLoadingSession, setIsLoadingSession] = useState(true)
 
   const wsRef = useRef<WebSocket | null>(null)
   const isConnectingRef = useRef(false)
@@ -290,6 +290,39 @@ export function usePicoChat() {
     return () => disconnect()
   }, [disconnect])
 
+  // Load most recent session on initial mount
+  useEffect(() => {
+    const loadRecentSession = async () => {
+      try {
+        const sessions = await getSessions(0, 1)
+        if (sessions.length > 0) {
+          const recentSession = sessions[0]
+          const detail = await getSessionHistory(recentSession.id)
+          const fallbackTime = detail.updated
+          const historyMessages = detail.messages.map((m, i) => ({
+            id: `hist-${i}-${Date.now()}`,
+            role: m.role as "user" | "assistant",
+            content: m.content,
+            timestamp: fallbackTime,
+          }))
+          setActiveSessionId(recentSession.id)
+          setMessages(historyMessages)
+        } else {
+          // No existing sessions, create a new one
+          setActiveSessionId(generateSessionId())
+        }
+      } catch (err) {
+        console.error("Failed to load recent session:", err)
+        // Fall back to new session on error
+        setActiveSessionId(generateSessionId())
+      } finally {
+        setIsLoadingSession(false)
+      }
+    }
+
+    void loadRecentSession()
+  }, [])
+
   const sendMessage = useCallback((content: string) => {
     if (!wsRef.current || wsRef.current.readyState !== WebSocket.OPEN) {
       console.warn("WebSocket not connected")
@@ -379,6 +412,7 @@ export function usePicoChat() {
     connectionState,
     isTyping,
     activeSessionId,
+    isLoadingSession,
     sendMessage,
     switchSession,
     newChat,

web/frontend/src/i18n/locales/en.json

@@ -31,6 +31,7 @@
     "historyLoadFailed": "Failed to load chat history",
     "historyOpenFailed": "Failed to open this chat history",
     "loadingMore": "Loading more...",
+    "loading": "Loading...",
     "deleteSession": "Delete session",
     "messagesCount": "{{count}} messages",
     "noModel": "Select model",

web/frontend/src/i18n/locales/zh.json

@@ -31,6 +31,7 @@
     "historyLoadFailed": "加载历史记录失败",
     "historyOpenFailed": "打开该历史会话失败",
     "loadingMore": "加载更多...",
+    "loading": "加载中...",
     "deleteSession": "删除会话",
     "messagesCount": "{{count}} 条消息",
     "noModel": "选择模型",