diff --git a/frontend/app/chat/page.tsx b/frontend/app/chat/page.tsx
index 8ec74c9..fb25834 100644
--- a/frontend/app/chat/page.tsx
+++ b/frontend/app/chat/page.tsx
@@ -4,10 +4,11 @@ import { useEffect, useState, useSyncExternalStore } from "react";
 import { ChatWidget } from "@/components/visitor/ChatWidget";
 import { FloatingButton } from "@/components/visitor/FloatingButton";
 import { isChatEmbedMode } from "@/lib/chat-embed";
+import { getOrCreateVisitorId } from "@/lib/visitor-id";
 
 /**
  * 访客聊天页面
- * - 独立打开：右下角浮动按钮 + 聊天小窗
+ * - 独立打开：默认展开聊天小窗（仍保留右下角浮动按钮）
  * - iframe / ?embed=1：直接铺满，供宿主站点一次点击打开 iframe 即可使用
  */
 export default function ChatPage() {
@@ -19,17 +20,16 @@ export default function ChatPage() {
     () => false
   );
 
-  // 初始化访客 ID（使用 localStorage 保持连续性）
   useEffect(() => {
-    let stored = window.localStorage.getItem("visitor_id");
-    if (!stored) {
-      stored = `${Date.now()}${Math.floor(Math.random() * 100000)}`;
-      window.localStorage.setItem("visitor_id", stored);
-    }
-    const parsed = Number.parseInt(stored, 10);
-    setVisitorId(Number.isNaN(parsed) ? null : parsed);
+    setVisitorId(getOrCreateVisitorId());
   }, []);
 
+  useEffect(() => {
+    if (!embedded && visitorId !== null) {
+      setIsOpen(true);
+    }
+  }, [embedded, visitorId]);
+
   const handleToggle = () => {
     setIsOpen((prev) => !prev);
   };
diff --git a/frontend/components/layout/Footer.tsx b/frontend/components/layout/Footer.tsx
index 8845ae0..248eb6a 100644
--- a/frontend/components/layout/Footer.tsx
+++ b/frontend/components/layout/Footer.tsx
@@ -5,10 +5,15 @@ import { Github, Mail, MessageSquare, Users } from "lucide-react";
 import { websiteConfig } from "@/lib/website-config";
 import { useI18n } from "@/lib/i18n/provider";
 
+interface FooterProps {
+  /** 首页打开右下角客服小窗；不传则回退为链到首页并带 openChat 参数 */
+  onOpenChat?: () => void;
+}
+
 /**
  * 官网底部页脚
  */
-export function Footer() {
+export function Footer({ onOpenChat }: FooterProps) {
   const { t } = useI18n();
 
   return (
@@ -145,10 +150,20 @@ export function Footer() {
                 </a>
               </li>
               <li className="flex items-center space-x-2 text-muted-foreground">
-                <MessageSquare className="h-4 w-4" />
-                <Link href="/chat" className="transition-colors hover:text-foreground">
-                  {t("footer.onlineChat")}
-                </Link>
+                <MessageSquare className="h-4 w-4 shrink-0" />
+                {onOpenChat ? (
+                  <button
+                    type="button"
+                    onClick={onOpenChat}
+                    className="text-left transition-colors hover:text-foreground"
+                  >
+                    {t("footer.onlineChat")}
+                  </button>
+                ) : (
+                  <Link href="/?openChat=1" className="transition-colors hover:text-foreground">
+                    {t("footer.onlineChat")}
+                  </Link>
+                )}
               </li>
             </ul>
           </div>
diff --git a/frontend/components/marketing/HomePageClient.tsx b/frontend/components/marketing/HomePageClient.tsx
index a870fa7..99e7f7a 100644
--- a/frontend/components/marketing/HomePageClient.tsx
+++ b/frontend/components/marketing/HomePageClient.tsx
@@ -28,6 +28,7 @@ import { Header } from "@/components/layout/Header";
 import { Footer } from "@/components/layout/Footer";
 import { FadeIn, FadeInStagger, FadeInItem } from "@/components/ui/fade-in";
 import { websiteConfig } from "@/lib/website-config";
+import { getOrCreateVisitorId } from "@/lib/visitor-id";
 import { stats } from "@/lib/stats-config";
 import type { I18nKey } from "@/lib/i18n/dict";
 import { useI18n } from "@/lib/i18n/provider";
@@ -149,15 +150,20 @@ export function HomePageClient() {
   const [activeScreenshot, setActiveScreenshot] = useState(0);
 
   useEffect(() => {
-    let stored = window.localStorage.getItem("visitor_id");
-    if (!stored) {
-      stored = `${Date.now()}${Math.floor(Math.random() * 100000)}`;
-      window.localStorage.setItem("visitor_id", stored);
-    }
-    const parsed = Number.parseInt(stored, 10);
-    setVisitorId(Number.isNaN(parsed) ? null : parsed);
+    setVisitorId(getOrCreateVisitorId());
   }, []);
 
+  useEffect(() => {
+    const params = new URLSearchParams(window.location.search);
+    if (params.get("openChat") === "1") {
+      handleOpenChat();
+      params.delete("openChat");
+      const next = `${window.location.pathname}${params.toString() ? `?${params}` : ""}`;
+      window.history.replaceState(null, "", next);
+    }
+    // eslint-disable-next-line react-hooks/exhaustive-deps -- 仅响应 URL 参数
+  }, [visitorId]);
+
   const handleToggleChat = () => setIsChatOpen((prev) => !prev);
 
   const handleOpenChat = () => {
@@ -469,7 +475,7 @@ export function HomePageClient() {
         </div>
       </section>
 
-      <Footer />
+      <Footer onOpenChat={handleOpenChat} />
 
       {visitorId !== null && (
         <>
diff --git a/frontend/lib/visitor-id.ts b/frontend/lib/visitor-id.ts
new file mode 100644
index 0000000..b1823f7
--- /dev/null
+++ b/frontend/lib/visitor-id.ts
@@ -0,0 +1,16 @@
+/**
+ * 访客 ID：写入 localStorage，保证为可安全表示的正整数。
+ * 旧版 `${Date.now()}${random}` 拼接过长会导致精度问题，此处会迁移为新格式。
+ */
+export function getOrCreateVisitorId(): number {
+  const stored = window.localStorage.getItem("visitor_id");
+  if (stored) {
+    const parsed = Number.parseInt(stored, 10);
+    if (!Number.isNaN(parsed) && parsed > 0) {
+      return parsed;
+    }
+  }
+  const id = Date.now() * 1000 + Math.floor(Math.random() * 100000);
+  window.localStorage.setItem("visitor_id", String(id));
+  return id;
+}