feat(chat): implement external browser prompt logic and update tests

src/app/chat/__tests__/chat-screen.helpers.test.ts

@@ -1,10 +1,15 @@
-import { describe, expect, it } from "vitest";
+import { afterEach, describe, expect, it, vi } from "vitest";
 
 import {
   getInsufficientCreditsMessageLimitView,
+  shouldStartExternalBrowserPrompt,
   shouldShowMessageLimitBanner,
 } from "../chat-screen.helpers";
 
+afterEach(() => {
+  vi.unstubAllEnvs();
+});
+
 describe("getInsufficientCreditsMessageLimitView", () => {
   it("asks guests to log in for more free chats", () => {
     expect(getInsufficientCreditsMessageLimitView("guest")).toEqual({
@@ -65,3 +70,73 @@ describe("shouldShowMessageLimitBanner", () => {
     ).toBe(false);
   });
 });
+
+describe("shouldStartExternalBrowserPrompt", () => {
+  it("shows for facebook users inside an in-app browser", () => {
+    vi.stubEnv("NEXT_PUBLIC_APP_ENV", "production");
+
+    expect(
+      shouldStartExternalBrowserPrompt({
+        hasInitialized: true,
+        isLoading: false,
+        loginStatus: "facebook",
+        isInAppBrowser: true,
+      }),
+    ).toBe(true);
+  });
+
+  it.each(["guest", "notLoggedIn", "email", "google"] as const)(
+    "hides for %s users even inside an in-app browser",
+    (loginStatus) => {
+      vi.stubEnv("NEXT_PUBLIC_APP_ENV", "production");
+
+      expect(
+        shouldStartExternalBrowserPrompt({
+          hasInitialized: true,
+          isLoading: false,
+          loginStatus,
+          isInAppBrowser: true,
+        }),
+      ).toBe(false);
+    },
+  );
+
+  it("hides for facebook users in normal browsers", () => {
+    vi.stubEnv("NEXT_PUBLIC_APP_ENV", "production");
+
+    expect(
+      shouldStartExternalBrowserPrompt({
+        hasInitialized: true,
+        isLoading: false,
+        loginStatus: "facebook",
+        isInAppBrowser: false,
+      }),
+    ).toBe(false);
+  });
+
+  it("shows in development for easier testing", () => {
+    vi.stubEnv("NEXT_PUBLIC_APP_ENV", "development");
+
+    expect(
+      shouldStartExternalBrowserPrompt({
+        hasInitialized: true,
+        isLoading: false,
+        loginStatus: "guest",
+        isInAppBrowser: false,
+      }),
+    ).toBe(true);
+  });
+
+  it("waits for auth initialization", () => {
+    vi.stubEnv("NEXT_PUBLIC_APP_ENV", "production");
+
+    expect(
+      shouldStartExternalBrowserPrompt({
+        hasInitialized: false,
+        isLoading: false,
+        loginStatus: "facebook",
+        isInAppBrowser: true,
+      }),
+    ).toBe(false);
+  });
+});

src/app/chat/chat-screen.helpers.ts

@@ -8,6 +8,7 @@ export interface ExternalBrowserPromptState {
   hasInitialized: boolean;
   isLoading: boolean;
   loginStatus: LoginStatus;
+  isInAppBrowser?: boolean;
 }
 
 export type InsufficientCreditsAction = "auth" | "topup";
@@ -63,11 +64,12 @@ export function shouldStartExternalBrowserPrompt({
   hasInitialized,
   isLoading,
   loginStatus,
+  isInAppBrowser = BrowserDetector.isInAppBrowser(),
 }: ExternalBrowserPromptState): boolean {
   if (!hasInitialized || isLoading) return false;
   return (
     isChatDevelopmentEnvironment() ||
-    (loginStatus === "facebook" && BrowserDetector.isInAppBrowser())
+    (loginStatus === "facebook" && isInAppBrowser)
   );
 }
 

src/app/chat/chat-screen.tsx

@@ -28,7 +28,7 @@ import {
 } from "./chat-image-overlay-url";
 import {
   deriveIsGuest,
-  isChatDevelopmentEnvironment,
+  shouldStartExternalBrowserPrompt,
 } from "./chat-screen.helpers";
 import { useFirstRechargeOfferBanner } from "./hooks/use-first-recharge-offer-banner";
 import { useChatUnlockNavigationFlow } from "./hooks/use-chat-unlock-navigation-flow";
@@ -90,6 +90,11 @@ export function ChatScreen() {
     loginStatus: authState.loginStatus,
   });
   const shouldShowPwaInstall = state.historyLoaded && state.messages.length >= 10;
+  const shouldShowBrowserHint = shouldStartExternalBrowserPrompt({
+    hasInitialized: authState.hasInitialized,
+    isLoading: authState.isLoading,
+    loginStatus: authState.loginStatus,
+  });
 
   useChatGuestLogin({
     dispatch: authDispatch,
@@ -186,7 +191,7 @@ export function ChatScreen() {
         </div>
 
         {/* 浏览器提示（应用内浏览器检测） */}
-        <BrowserHintOverlay forceShow={isChatDevelopmentEnvironment()} />
+        {shouldShowBrowserHint ? <BrowserHintOverlay forceShow /> : null}
 
         {/* PWA 安装提示触发器（聊天消息数量达到阈值后才允许弹出） */}
         <PwaInstallOverlay enabled={shouldShowPwaInstall} />

src/app/chat/components/browser-hint-overlay.tsx

@@ -14,7 +14,6 @@ import { useEffect, useState } from "react";
 import { ExternalLink } from "lucide-react";
 
 import { openChatInExternalBrowser } from "@/lib/chat/chat_external_browser";
-import { BrowserDetector } from "@/utils";
 
 import styles from "./browser-hint-overlay.module.css";
 
@@ -39,13 +38,11 @@ export function BrowserHintOverlay({
   forceShow = false,
   autoCollapseDelayMs = DEFAULT_AUTO_COLLAPSE_DELAY_MS,
 }: BrowserHintOverlayProps) {
-  // lazy initializer：首次渲染即计算（避免 useEffect 中调 setState 的 lint 错）
-  const [isInAppBrowser] = useState(BrowserDetector.isInAppBrowser);
   const [isExpanded, setIsExpanded] = useState(true);
   const [hasAutoCollapsed, setHasAutoCollapsed] = useState(false);
 
-  // 开发模式或应用内浏览器才显示
+  // 展示条件由调用方控制；forceShow 保留给开发/测试入口。
-  const shouldShow = forceShow || isInAppBrowser;
+  const shouldShow = forceShow;
 
   useEffect(() => {
     if (!shouldShow || hasAutoCollapsed || autoCollapseDelayMs <= 0) return;