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

memento-note/lib/billing/cancel-subscription.ts

@@ -0,0 +1,66 @@
+import { prisma } from '@/lib/prisma';
+import { stripe } from '@/lib/stripe';
+
+export interface CancelSubscriptionResult {
+  success: boolean;
+  error?: string;
+}
+
+/**
+ * Cancels an active user subscription by setting its auto-renew (cancel_at_period_end) status to true
+ * in Stripe and synchronizing the status back into the local Prisma database.
+ * 
+ * @param userId - Unique identifier of the user
+ * @returns An object indicating the success or failure of the operation
+ */
+export async function cancelSubscription(userId: string): Promise<CancelSubscriptionResult> {
+  if (!userId) {
+    return { success: false, error: 'User ID is required' };
+  }
+
+  try {
+    const subscription = await prisma.subscription.findUnique({
+      where: { userId },
+    });
+
+    if (!subscription) {
+      return { success: false, error: 'No active subscription found' };
+    }
+
+    if (subscription.stripeSubscriptionId) {
+      // Direct call to Stripe API with period end cancellation set to true
+      const updatedSub = await stripe.subscriptions.update(subscription.stripeSubscriptionId, {
+        cancel_at_period_end: true,
+      });
+
+      // Local database synchronization
+      await prisma.subscription.update({
+        where: { userId },
+        data: {
+          cancelAtPeriodEnd: true,
+          canceledAt: updatedSub.canceled_at ? new Date(updatedSub.canceled_at * 1000) : new Date(),
+          currentPeriodEnd: updatedSub.current_period_end ? new Date(updatedSub.current_period_end * 1000) : subscription.currentPeriodEnd,
+          updatedAt: new Date(),
+        },
+      });
+    } else {
+      // Mock mode cancel (e.g. for development / local bypass testing)
+      await prisma.subscription.update({
+        where: { userId },
+        data: {
+          cancelAtPeriodEnd: true,
+          canceledAt: new Date(),
+          updatedAt: new Date(),
+        },
+      });
+    }
+
+    return { success: true };
+  } catch (error: any) {
+    console.error('[cancelSubscription] Error processing cancellation:', error);
+    return {
+      success: false,
+      error: error.message || 'Failed to cancel subscription',
+    };
+  }
+}