Session 10: Internal auth refactor, prefetch cascade keys, Sentry, welcome email (1286 tests)

web/src/app/welcome/page.tsx

@@ -2,16 +2,34 @@
 
 import { useRouter } from 'next/navigation';
 import { useAuth } from '@/contexts/AuthContext';
-import { useEffect } from 'react';
+import { useEffect, useRef } from 'react';
 
 export default function WelcomePage() {
   const router = useRouter();
-  const { user, loading } = useAuth();
+  const { user, session, loading } = useAuth();
+  const welcomeFiredRef = useRef(false);
 
   useEffect(() => {
     if (!loading && !user) router.replace('/signup');
   }, [loading, user, router]);
 
+  // Session 10 — trigger the welcome email exactly once per mount.
+  // The server-side handler is idempotent via user_metadata
+  // (welcome_email_sent flag), so re-triggers from a refresh are
+  // safe; the ref is just a UX optimization to avoid duplicate
+  // network requests on this page.
+  useEffect(() => {
+    if (welcomeFiredRef.current) return;
+    if (loading || !user || !session) return;
+    welcomeFiredRef.current = true;
+    fetch('/api/welcome-email', {
+      method: 'POST',
+      headers: { Authorization: `Bearer ${session.access_token}` },
+    }).catch(() => {
+      // Fail silent — onboarding must not block on email outages.
+    });
+  }, [loading, user, session]);
+
   return (
     <section
       className="tex-scan"