feat: implement audit logging system with service, controller, and interceptor to track user actions across core services

src/stripe/stripe-webhook.controller.ts

@@ -14,6 +14,8 @@ import { StripeService } from './stripe.service';
 import { SubscriptionService } from './subscription.service';
 import { Public } from '../auth/decorators/public.decorator';
 import { SubscriptionStatus } from '@prisma/client';
+import { AuditService } from '../audit/audit.service';
+import { AuditAction } from '../audit/audit.constants';
 
 @ApiTags('Stripe Webhooks')
 @Controller('stripe')
@@ -23,6 +25,7 @@ export class StripeWebhookController {
   constructor(
     private stripeService: StripeService,
     private subscriptionService: SubscriptionService,
+    private audit: AuditService,
   ) {}
 
   @Public()
@@ -131,6 +134,14 @@ export class StripeWebhookController {
       currentPeriodEnd,
     });
 
+    this.audit.log({
+      action: AuditAction.SUBSCRIPTION_CREATE,
+      resourceType: 'AgentSubscription',
+      resourceId: stripeSubscriptionId,
+      metadata: { userId, planId, stripeCustomerId },
+      actorOverride: { id: null, role: 'SYSTEM' },
+    });
+
     this.logger.log(`Created subscription for user ${userId}, plan ${planId}`);
   }
 
@@ -156,6 +167,19 @@ export class StripeWebhookController {
       receiptUrl: invoice.hosted_invoice_url,
     });
 
+    this.audit.log({
+      action: AuditAction.PAYMENT_SUCCESS,
+      resourceType: 'Payment',
+      resourceId: invoice.id,
+      metadata: {
+        userId: subscription.userId,
+        amount: invoice.amount_paid,
+        currency: invoice.currency,
+        stripeSubscriptionId,
+      },
+      actorOverride: { id: null, role: 'SYSTEM' },
+    });
+
     // Update subscription period
     const periodEnd = invoice.lines?.data?.[0]?.period?.end;
     const periodStart = invoice.lines?.data?.[0]?.period?.start;
@@ -193,6 +217,19 @@ export class StripeWebhookController {
       SubscriptionStatus.PAST_DUE,
     );
 
+    this.audit.log({
+      action: AuditAction.PAYMENT_FAILURE,
+      resourceType: 'Payment',
+      resourceId: invoice.id,
+      metadata: {
+        userId: subscription.userId,
+        amount: invoice.amount_due,
+        currency: invoice.currency,
+        stripeSubscriptionId,
+      },
+      actorOverride: { id: null, role: 'SYSTEM' },
+    });
+
     this.logger.warn(`Payment failed for subscription ${stripeSubscriptionId}`);
   }
 
@@ -224,6 +261,14 @@ export class StripeWebhookController {
       { canceledAt: new Date() },
     );
 
+    this.audit.log({
+      action: AuditAction.SUBSCRIPTION_CANCEL,
+      resourceType: 'AgentSubscription',
+      resourceId: subscription.id,
+      metadata: { source: 'stripe_webhook' },
+      actorOverride: { id: null, role: 'SYSTEM' },
+    });
+
     this.logger.log(`Subscription ${subscription.id} cancelled`);
   }
 }

src/stripe/stripe.service.ts

@@ -2,6 +2,8 @@ import { Injectable, Logger, BadRequestException } from '@nestjs/common';
 import { ConfigService } from '@nestjs/config';
 import Stripe from 'stripe';
 import { PrismaService } from '../prisma/prisma.service';
+import { AuditService } from '../audit/audit.service';
+import { AuditAction } from '../audit/audit.constants';
 
 @Injectable()
 export class StripeService {
@@ -11,6 +13,7 @@ export class StripeService {
   constructor(
     private configService: ConfigService,
     private prisma: PrismaService,
+    private audit: AuditService,
   ) {
     const secretKey = this.configService.get<string>('stripe.secretKey');
     if (secretKey) {
@@ -180,13 +183,20 @@ export class StripeService {
     stripeSubscriptionId: string,
     atPeriodEnd = true,
   ): Promise<Stripe.Subscription> {
-    if (atPeriodEnd) {
-      return this.getStripe().subscriptions.update(stripeSubscriptionId, {
-        cancel_at_period_end: true,
-      });
-    }
+    const result = atPeriodEnd
+      ? await this.getStripe().subscriptions.update(stripeSubscriptionId, {
+          cancel_at_period_end: true,
+        })
+      : await this.getStripe().subscriptions.cancel(stripeSubscriptionId);
 
-    return this.getStripe().subscriptions.cancel(stripeSubscriptionId);
+    this.audit.log({
+      action: AuditAction.SUBSCRIPTION_CANCEL,
+      resourceType: 'AgentSubscription',
+      resourceId: stripeSubscriptionId,
+      metadata: { atPeriodEnd, source: 'agent_action' },
+    });
+
+    return result;
   }
 
   async getSubscription(