Updated project changes

api/payments/create-checkout-session.js

@@ -38,8 +38,24 @@ export default async function handler(req, res) {
     }
 
     try {
-        const { invoiceId, customerEmail } = req.body || {};
-        const invoice = INVOICES[invoiceId];
+        const { invoiceId, customerEmail, fallback } = req.body || {};
+
+        // The static map is authoritative for seed invoices (amount can't be
+        // tampered). DEMO ONLY: invoices the owner created live in the browser's
+        // localStorage, so the server doesn't know them — accept the client's
+        // amount/title as a fallback for those. In production every invoice would
+        // be resolved from the billing DB here and this fallback removed.
+        let invoice = INVOICES[invoiceId];
+        if (!invoice && fallback) {
+            const amount = Number(fallback.amount);
+            if (Number.isInteger(amount) && amount > 0) {
+                invoice = {
+                    title: String(fallback.title || 'Payment').slice(0, 200),
+                    amount,
+                    currency: (fallback.currency || 'usd').toLowerCase(),
+                };
+            }
+        }
         if (!invoice) {
             return res.status(404).json({ error: `Unknown invoice: ${invoiceId}` });
         }