feat(billing): implement robust in-app subscription cancellation & fix CI/CD socket port typo

memento-note/app/api/billing/create-checkout/route.ts

@@ -31,21 +31,41 @@ export async function POST(req: NextRequest) {
     const subscription = await prisma.subscription.findUnique({ where: { userId } });
     let customerId = subscription?.stripeCustomerId ?? undefined;
 
+    if (customerId && customerId.startsWith('cus_mock')) {
+      customerId = undefined;
+    }
+
     if (!customerId) {
       const customer = await stripe.customers.create({
         email: userEmail,
         metadata: { userId },
       });
       customerId = customer.id;
+      
+      // Update DB to save the real Stripe customer ID
+      await prisma.subscription.upsert({
+        where: { userId },
+        update: { stripeCustomerId: customerId },
+        create: {
+          userId,
+          stripeCustomerId: customerId,
+          tier: 'BASIC',
+          status: 'ACTIVE',
+          currentPeriodStart: new Date(),
+          currentPeriodEnd: new Date(Date.now() + 30 * 24 * 3600 * 1000), // temp basic dates
+        }
+      });
     }
 
-    const origin = req.headers.get('origin') ?? process.env.NEXTAUTH_URL ?? 'http://localhost:3000';
+    const host = req.headers.get('x-forwarded-host') ?? req.headers.get('host') ?? 'localhost:3000';
+    const proto = req.headers.get('x-forwarded-proto') ?? 'http';
+    const origin = `${proto}://${host}`;
 
     const sessionParams = {
       customer: customerId,
       mode: 'subscription' as const,
       line_items: [{ price: priceId, quantity: 1 }],
-      ui_mode: 'embedded',
+      ui_mode: 'embedded_page',
       return_url: `${origin}/settings/billing?session_id={CHECKOUT_SESSION_ID}`,
       metadata: { userId, tier },
       subscription_data: { metadata: { userId, tier } },