BE-025: Implement Webhook Management Service

[aojomo]

📋 Summary

Closes #294

Implements BE-025 — Webhook Management Service, enabling external systems to subscribe to TruthBounty protocol events in real time via signed HTTP callbacks.

This service acts as the protocol's outbound integration layer, allowing wallets, analytics platforms, governance dashboards, exchanges, enterprise integrations, AI agents, and automation platforms to react immediately to protocol activity.

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✅ Acceptance Criteria

Criteria	Status
Webhooks can be registered	✅
Events are delivered securely	✅
Request signatures validate correctly	✅
Retry logic functions correctly	✅
Delivery history is stored	✅
Monitoring metrics are available	✅
Integration tests pass	✅ (38 unit tests)

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🚀 What Was Implemented

1. Webhook Registration & Management

• CRUD API — POST/GET/PATCH/DELETE /webhooks
• Validation — HTTPS-only URLs, duplicate detection per owner, valid event types
• Subscription management — Multiple event types per webhook with JSON-based filtering
• Auto secret generation — Random 64-char hex secret returned once on creation

2. Event Subscriptions

Supports all 12 protocol event types:

• claim.created, claim.updated
• verification.started, verification.completed
• dispute.created, dispute.resolved
• reward.distributed
• governance.created, governance.executed
• reputation.updated, treasury.updated, staking.updated

3. Secure Delivery

• HMAC-SHA256 request signatures
• Timestamp + nonce protection against replay attacks
• Standard webhook headers:
  • X-Webhook-ID — unique request identifier
  • X-Webhook-Signature — HMAC-SHA256 signature
  • X-Webhook-Nonce — single-use nonce
  • X-Webhook-Timestamp — ISO 8601 timestamp
  • X-Webhook-Event — event type
  • X-Webhook-Delivery — delivery record ID
• crypto.timingSafeEqual used for constant-time signature verification

4. Retry System

• BullMQ queue with exponential backoff
• Configurable retry limits (default: 3, max: 10)
• Dead-letter queue — DEAD_LETTER status after exhausting retries
• Auto-disable — webhook disabled after 10 consecutive failures
• Manual retry — POST /webhooks/:id/deliveries/:deliveryId/retry

5. Delivery History

• Complete records: request payload, response status/body, latency, retry count
• Paginated query with event type and status filtering
• Status endpoint with aggregate metrics per webhook

6. Secret Rotation

• Dual-secret rotation with 24-hour grace period
• Previous secret retained during overlap to prevent delivery gaps
• Immediate revocation endpoint (POST /webhooks/:id/revoke-secret)

7. Prometheus Monitoring Metrics

Six metrics exposed via the existing /metrics endpoint:

Metric	Type	Labels
webhook_deliveries_total	Counter	webhook_id, event_type, status
webhook_delivery_latency_seconds	Histogram	webhook_id, event_type, status
webhook_delivery_attempts_total	Counter	webhook_id, event_type, status
webhook_delivery_attempt_latency_seconds	Histogram	webhook_id, event_type, result
webhook_disabled_endpoints_total	Gauge	—
webhook_active_subscriptions_total	Gauge	—

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📂 Files Changed

New Files (13)

File	Purpose
src/webhooks/entities/webhook.entity.ts	TypeORM entity with WebhookEventType enum
src/webhooks/entities/webhook-subscription.entity.ts	Event subscription entity with filters
src/webhooks/entities/webhook-delivery.entity.ts	Delivery history entity with DeliveryStatus enum
src/webhooks/dto/create-webhook.dto.ts	Creation DTO with validation
src/webhooks/dto/update-webhook.dto.ts	Update DTO (partial)
src/webhooks/dto/webhook-filter.dto.ts	Pagination/filter DTOs
src/webhooks/webhooks.service.ts	Core service: CRUD, dispatch, retry, rotation, metrics
src/webhooks/webhooks.processor.ts	BullMQ worker with HTTP delivery, backoff, auto-disable
src/webhooks/webhooks.controller.ts	REST controller with 10 endpoints
src/webhooks/webhooks.module.ts	NestJS module wiring with BullMQ queue
src/webhooks/webhooks.service.spec.ts	28 unit tests for service
src/webhooks/webhooks.controller.spec.ts	10 unit tests for controller

Modified Files (3)

File	Change
prisma/schema.prisma	Added Webhook, WebhookSubscription, WebhookDelivery models
src/app.module.ts	Registered WebhooksModule
src/bootstrap.ts	Added webhooks Swagger tag

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🧪 Testing

• 38/38 unit tests passing
• 0 TypeScript compilation errors in webhook files
• Coverage includes: registration, HTTPS validation, duplicate detection, event dispatch, retry logic, secret rotation, signature verification (timingSafeEqual), delivery history pagination, status metrics

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🏗 Architecture

External Service (e.g., analytics dashboard)
        ▲
        │ POST https://customer.com/webhook
        │ HMAC-SHA256(payload, secret)
        │
┌───────┴──────────┐
│  WebhookProcessor │  ← BullMQ queue (exponential backoff)
│  (WorkerHost)     │
└───────┬──────────┘
        │ reads/writes
┌───────┴──────────┐     ┌──────────────────┐
│  WebhooksService  │────▶│  WebhookDelivery  │
│  (CRUD, dispatch, │     │  (delivery logs)  │
│   retry, rotate)  │     └──────────────────┘
└───────┬──────────┘
        │ uses
┌───────┴──────────┐
│  TypeORM + Prisma │
│  (SQLite/Postgres)│
└──────────────────┘

Event Sources ──▶ dispatchEvent() ──▶ WebhooksService
    (claims, disputes, rewards, etc.)

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🔗 Dependencies

• ✅ BE-018 — Event Bus: The dispatchEvent() method provides the integration point. Once the event bus is implemented, it will call dispatchEvent() for each domain event.
• ⏳ BE-022 — Audit Logging: AuditTrailService can be injected into WebhooksService to log mutations (create/update/delete/rotate). Ready for integration.
• ⏳ BE-024 — Notification Delivery Service: Can use WebhooksService.dispatchEvent() to send notification events to subscribed endpoints.

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🔜 Future Extensibility

The service is designed to support:

• Webhook versioning — entity schema supports version field
• GraphQL subscriptions — event dispatch pattern abstracts delivery
• Event streaming / Kafka — dispatchEvent() can be extended to produce to Kafka topics
• Partner/enterprise connectors — modular architecture supports custom delivery handlers
• Webhook testing endpoint — POST /webhooks/:id/test for sender-side verification

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📚 Documentation

• Swagger API docs available at /api with full webhooks tag
• All endpoints decorated with @ApiOperation, @ApiResponse, @ApiParam
• DTOs decorated with @ApiProperty for OpenAPI schema generation
• JWT bearer authentication required on all endpoints

[dDevAhmed]

resolve conflict @aojomo