fix(platform-service): make Stripe webhook product routing resilient

- Added cross-product fallback lookup by stripeCustomerId when metadata lacks productId
- Ensure invoice payments are stored under the resolved subscription productId
- Normalize checkout metadata plan value before persistence/sync
- Keep auth plan sync aligned with resolved product context
- Verified: tsc --noEmit clean, 20 test files / 183 tests passing

services/platform-service/src/modules/stripe/routes.ts

@@ -115,7 +115,7 @@ export async function stripeRoutes(app: FastifyInstance) {
       case 'checkout.session.completed': {
         const session = event.data.object as Stripe.Checkout.Session;
         const userId = session.metadata?.userId;
-        const plan = session.metadata?.plan || 'pro';
+        const plan = normalizePlan(session.metadata?.plan) ?? 'pro';
         if (userId && session.customer) {
           const existing = await subRepo.getByUserId(userId, eventProductId);
           const now = new Date();
@@ -177,8 +177,11 @@ export async function stripeRoutes(app: FastifyInstance) {
       case 'customer.subscription.updated': {
         const sub = event.data.object as Stripe.Subscription;
         const customerId = typeof sub.customer === 'string' ? sub.customer : sub.customer.id;
-        const existing = await subRepo.getByStripeCustomerId(customerId, eventProductId);
+        const existing = metadata?.productId
+          ? await subRepo.getByStripeCustomerId(customerId, eventProductId)
+          : await subRepo.getByStripeCustomerIdAnyProduct(customerId);
         if (existing) {
+          const effectiveProductId = existing.productId;
           const updatedPlan = getPlanFromSubscription(sub) ?? existing.plan;
           const newStatus = sub.cancel_at_period_end
             ? 'cancelled'
@@ -191,7 +194,7 @@ export async function stripeRoutes(app: FastifyInstance) {
             cancelAtPeriodEnd: sub.cancel_at_period_end,
             currentPeriodEnd: new Date(sub.current_period_end * 1000).toISOString(),
           });
-          await authRepo.updatePlan(existing.userId, eventProductId, updatedPlan);
+          await authRepo.updatePlan(existing.userId, effectiveProductId, updatedPlan);
           // Sync plan to backend users container
           await syncUserPlan(existing.userId, updatedPlan, app.log);
         }
@@ -201,14 +204,17 @@ export async function stripeRoutes(app: FastifyInstance) {
       case 'customer.subscription.deleted': {
         const sub = event.data.object as Stripe.Subscription;
         const customerId = typeof sub.customer === 'string' ? sub.customer : sub.customer.id;
-        const existing = await subRepo.getByStripeCustomerId(customerId, eventProductId);
+        const existing = metadata?.productId
+          ? await subRepo.getByStripeCustomerId(customerId, eventProductId)
+          : await subRepo.getByStripeCustomerIdAnyProduct(customerId);
         if (existing) {
+          const effectiveProductId = existing.productId;
           await subRepo.updateSubscription(existing.id, existing.userId, {
             status: 'cancelled',
             plan: 'free',
             cancelAtPeriodEnd: false,
           });
-          await authRepo.updatePlan(existing.userId, eventProductId, 'free');
+          await authRepo.updatePlan(existing.userId, effectiveProductId, 'free');
           // Sync plan downgrade to backend users container
           await syncUserPlan(existing.userId, 'free', app.log);
         }
@@ -220,11 +226,13 @@ export async function stripeRoutes(app: FastifyInstance) {
         const customerId =
           typeof invoice.customer === 'string' ? invoice.customer : invoice.customer?.id;
         if (customerId) {
-          const existing = await subRepo.getByStripeCustomerId(customerId, eventProductId);
+          const existing = metadata?.productId
+            ? await subRepo.getByStripeCustomerId(customerId, eventProductId)
+            : await subRepo.getByStripeCustomerIdAnyProduct(customerId);
           if (existing && invoice.amount_paid > 0) {
             await subRepo.createPayment({
               id: `pay_${randomUUID()}`,
-              productId: eventProductId,
+              productId: existing.productId,
               userId: existing.userId,
               amount: invoice.amount_paid,
               currency: invoice.currency,
@@ -286,3 +294,8 @@ function getPlanFromSubscription(sub: Stripe.Subscription): SubscriptionDoc['pla
   if (priceId === priceIds.pro) return 'pro';
   return null;
 }
+
+function normalizePlan(plan: string | undefined): SubscriptionDoc['plan'] | null {
+  if (plan === 'free' || plan === 'pro' || plan === 'enterprise') return plan;
+  return null;
+}

services/platform-service/src/modules/subscriptions/repository.ts

@@ -32,6 +32,18 @@ export async function getByUserId(
   return resources[0] ?? null;
 }
 
+export async function getByStripeCustomerIdAnyProduct(
+  stripeCustomerId: string
+): Promise<SubscriptionDoc | null> {
+  const { resources } = await subContainer()
+    .items.query<SubscriptionDoc>({
+      query: 'SELECT * FROM c WHERE c.stripeCustomerId = @cid ORDER BY c.createdAt DESC',
+      parameters: [{ name: '@cid', value: stripeCustomerId }],
+    })
+    .fetchAll();
+  return resources[0] ?? null;
+}
+
 export async function getByStripeCustomerId(
   stripeCustomerId: string,
   productId: string