## Fix: mobile signup modal freeze (defer Google Sign-In)

**Problem:** On mobile Safari, tapping "Sign up to create" on the create pages froze for 5–10s before the signup modal appeared. Desktop was fine.

**Cause:** The modal mounts Google's GSI sign-in widget (`<GoogleLogin>`), which boots a cross-site iframe to `accounts.google.com`. Mobile Safari's tracking prevention (ITP) throttles that cross-site init for several seconds, and because the widget mounted synchronously when the modal opened, the modal's first paint was blocked behind it. The login/signup pages didn't show this because they mount the widget during a route change, hiding the cost.

**Fix:** Defer mounting the real GSI iframe until after first paint (`useEffect` + `requestAnimationFrame`). The custom "Continue with Google" button shows instantly; the actual Google button hydrates a frame later, off the critical path. The container has a fixed height, so there's no layout shift.

- Centralized in `GoogleLoginButton`, so the login/signup pages benefit too.
- Tradeoff: the Google button becomes clickable ~1 frame later (imperceptible).
- No behavior change on desktop.

frontend/apps/artcraft-webapp/src/components/auth/GoogleLoginButton.tsx

@@ -8,7 +8,7 @@ import {
 } from "@storyteller/common";
 import { faSpinnerThird } from "@fortawesome/pro-solid-svg-icons";
 import { FontAwesomeIcon } from "@fortawesome/react-fontawesome";
-import { useState } from "react";
+import { useEffect, useState } from "react";
 
 interface GoogleLoginButtonProps {
   onSuccess: (isNewUser: boolean) => void;
@@ -25,6 +25,17 @@ export function GoogleLoginButton({
 }: GoogleLoginButtonProps) {
   const [isLoading, setIsLoading] = useState(false);
 
+  // Defer mounting Google's GSI widget until after first paint. Its cross-site
+  // init stalls for several seconds on mobile Safari (ITP throttles
+  // accounts.google.com), so mounting it inline blocks the surrounding UI (e.g.
+  // the signup modal) from appearing. The custom visual button below shows
+  // instantly; the real Google button hydrates a frame later.
+  const [mountGsi, setMountGsi] = useState(false);
+  useEffect(() => {
+    const raf = requestAnimationFrame(() => setMountGsi(true));
+    return () => cancelAnimationFrame(raf);
+  }, []);
+
   const handleGoogleSuccess = async (
     credentialResponse: CredentialResponse,
   ) => {
@@ -75,19 +86,23 @@ export function GoogleLoginButton({
         )}
       </div>
 
-      {/* Google's actual button - invisible overlay that receives clicks */}
-      <div
-        className="absolute inset-0 w-full h-full overflow-hidden cursor-pointer flex items-center justify-center"
-        style={{ opacity: 0.01, zIndex: 10, transform: "scaleY(1.2)" }}
-      >
-        <GoogleLogin
-          onSuccess={handleGoogleSuccess}
-          onError={() => onError("Google login failed")}
-          size="large"
-          width={400}
-          text="continue_with"
-        />
-      </div>
+      {/* Google's actual button - invisible overlay that receives clicks.
+          Mounted after first paint (see mountGsi) so its slow cross-site init
+          never blocks the surrounding UI from showing. */}
+      {mountGsi && (
+        <div
+          className="absolute inset-0 w-full h-full overflow-hidden cursor-pointer flex items-center justify-center"
+          style={{ opacity: 0.01, zIndex: 10, transform: "scaleY(1.2)" }}
+        >
+          <GoogleLogin
+            onSuccess={handleGoogleSuccess}
+            onError={() => onError("Google login failed")}
+            size="large"
+            width={400}
+            text="continue_with"
+          />
+        </div>
+      )}
     </div>
   );
 }