fix: prevent duplicate subscriptions by validating active status in webhook and cleaning up stale records during creation

src/stripe/stripe-webhook.controller.ts

@@ -91,12 +91,19 @@ export class StripeWebhookController {
     const stripeCustomerId = session.customer as string;
 
     // Check if subscription already exists (idempotency)
-    const existing = await this.subscriptionService.getSubscriptionByStripeId(stripeSubscriptionId);
+    const existingByStripeId = await this.subscriptionService.getSubscriptionByStripeId(stripeSubscriptionId);
-    if (existing) {
+    if (existingByStripeId) {
       this.logger.log(`Subscription ${stripeSubscriptionId} already exists, skipping`);
       return;
     }
 
+    // Check if user already has an active subscription (prevent duplicates)
+    const existingActive = await this.subscriptionService.getActivePlan(userId);
+    if (existingActive) {
+      this.logger.log(`User ${userId} already has active subscription ${existingActive.id}, skipping duplicate`);
+      return;
+    }
+
     await this.subscriptionService.createSubscription({
       userId,
       planId,

src/stripe/stripe.service.ts

@@ -80,6 +80,34 @@ export class StripeService {
       throw new BadRequestException('You already have an active subscription');
     }
 
+    // Clean up any incomplete/failed subscriptions to prevent duplicates
+    // when user retries payment after a previous failure
+    const staleSubscriptions = await this.prisma.agentSubscription.findMany({
+      where: {
+        userId,
+        status: { in: ['INCOMPLETE', 'UNPAID', 'PAST_DUE'] },
+      },
+    });
+
+    if (staleSubscriptions.length > 0) {
+      // Cancel stale Stripe subscriptions before deleting DB records
+      for (const sub of staleSubscriptions) {
+        if (!sub.stripeSubscriptionId) continue;
+        try {
+          await this.getStripe().subscriptions.cancel(sub.stripeSubscriptionId);
+        } catch (err: any) {
+          this.logger.warn(`Could not cancel stale Stripe subscription ${sub.stripeSubscriptionId}: ${err.message}`);
+        }
+      }
+      await this.prisma.agentSubscription.deleteMany({
+        where: {
+          userId,
+          status: { in: ['INCOMPLETE', 'UNPAID', 'PAST_DUE'] },
+        },
+      });
+      this.logger.log(`Cleaned up ${staleSubscriptions.length} stale subscription(s) for user ${userId}`);
+    }
+
     // Get or create Stripe customer
     const user = await this.prisma.user.findUnique({
       where: { id: userId },