Add checkout.session.completed webhook handler for Pro key creation

- Extract customer email from session.customer_details?.email
- Check if Pro key already exists for that email (idempotent)
- Create Pro key only if one does not exist
- Add comprehensive logging for debugging
- Ensures webhook and success page work together without duplicates

src/routes/billing.ts

@@ -1,6 +1,6 @@
 import { Router, Request, Response } from "express";
 import Stripe from "stripe";
-import { createProKey, revokeByCustomer } from "../services/keys.js";
+import { createProKey, revokeByCustomer, getAllKeys } from "../services/keys.js";
 
 function escapeHtml(s: string): string {
   return s.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;").replace(/"/g, "&quot;").replace(/'/g, "&#39;");
@@ -105,6 +105,39 @@ router.post("/webhook", async (req: Request, res: Response) => {
   }
 
   switch (event.type) {
+    case "checkout.session.completed": {
+      const session = event.data.object as Stripe.Checkout.Session;
+      const customerId = session.customer as string;
+      const email = session.customer_details?.email;
+      
+      console.log(`[Webhook] checkout.session.completed - sessionId: ${session.id}, customerId: ${customerId}, email: ${email}`);
+      
+      if (!email) {
+        console.error(`[Webhook] No customer email found for session ${session.id}`);
+        break;
+      }
+      
+      if (!customerId) {
+        console.error(`[Webhook] No customer ID found for session ${session.id}`);
+        break;
+      }
+      
+      // Check if a Pro key already exists for this email (idempotent handling)
+      const existingKeys = getAllKeys();
+      const existingProKey = existingKeys.find(k => k.email === email && k.tier === "pro");
+      
+      if (existingProKey) {
+        console.log(`[Webhook] Pro key already exists for email ${email}, skipping creation`);
+      } else {
+        try {
+          const keyInfo = createProKey(email, customerId);
+          console.log(`[Webhook] Created Pro key for ${email}: ${keyInfo.key}`);
+        } catch (err: any) {
+          console.error(`[Webhook] Failed to create Pro key for ${email}:`, err.message);
+        }
+      }
+      break;
+    }
     case "customer.subscription.deleted": {
       const sub = event.data.object as Stripe.Subscription;
       const customerId = sub.customer as string;
@@ -113,6 +146,7 @@ router.post("/webhook", async (req: Request, res: Response) => {
       break;
     }
     default:
+      console.log(`[Webhook] Unhandled event type: ${event.type}`);
       break;
   }
 
@@ -154,4 +188,4 @@ async function getOrCreateProPrice(): Promise<string> {
   return cachedPriceId;
 }
 
-export { router as billingRouter };
+export { router as billingRouter };