Retell AI Reference Architecture

Overview

Production-ready architecture patterns for Retell AI integrations.

Prerequisites

Understanding of layered architecture
Retell AI SDK knowledge
TypeScript project setup
Testing framework configured

Project Structure

my-retellai-project/
├── src/
│   ├── retellai/
│   │   ├── client.ts           # Singleton client wrapper
│   │   ├── config.ts           # Environment configuration
│   │   ├── types.ts            # TypeScript types
│   │   ├── errors.ts           # Custom error classes
│   │   └── handlers/
│   │       ├── webhooks.ts     # Webhook handlers
│   │       └── events.ts       # Event processing
│   ├── services/
│   │   └── retellai/
│   │       ├── index.ts        # Service facade
│   │       ├── sync.ts         # Data synchronization
│   │       └── cache.ts        # Caching layer
│   ├── api/
│   │   └── retellai/
│   │       └── webhook.ts      # Webhook endpoint
│   └── jobs/
│       └── retellai/
│           └── sync.ts         # Background sync job
├── tests/
│   ├── unit/
│   │   └── retellai/
│   └── integration/
│       └── retellai/
├── config/
│   ├── retellai.development.json
│   ├── retellai.staging.json
│   └── retellai.production.json
└── docs/
    └── retellai/
        ├── SETUP.md
        └── RUNBOOK.md

Layer Architecture

┌─────────────────────────────────────────┐
│             API Layer                    │
│   (Controllers, Routes, Webhooks)        │
├─────────────────────────────────────────┤
│           Service Layer                  │
│  (Business Logic, Orchestration)         │
├─────────────────────────────────────────┤
│          Retell AI Layer        │
│   (Client, Types, Error Handling)        │
├─────────────────────────────────────────┤
│         Infrastructure Layer             │
│    (Cache, Queue, Monitoring)            │
└─────────────────────────────────────────┘

Key Components

Step 1: Client Wrapper

// src/retellai/client.ts
export class Retell AIService {
  private client: RetellAIClient;
  private cache: Cache;
  private monitor: Monitor;

  constructor(config: Retell AIConfig) {
    this.client = new RetellAIClient(config);
    this.cache = new Cache(config.cacheOptions);
    this.monitor = new Monitor('retellai');
  }

  async get(id: string): Promise<Resource> {
    return this.cache.getOrFetch(id, () =>
      this.monitor.track('get', () => this.client.get(id))
    );
  }
}

Step 2: Error Boundary

// src/retellai/errors.ts
export class Retell AIServiceError extends Error {
  constructor(
    message: string,
    public readonly code: string,
    public readonly retryable: boolean,
    public readonly originalError?: Error
  ) {
    super(message);
    this.name = 'Retell AIServiceError';
  }
}

export function wrapRetell AIError(error: unknown): Retell AIServiceError {
  // Transform SDK errors to application errors
}

Step 3: Health Check

// src/retellai/health.ts
export async function checkRetell AIHealth(): Promise<HealthStatus> {
  try {
    const start = Date.now();
    await retellaiClient.ping();
    return {
      status: 'healthy',
      latencyMs: Date.now() - start,
    };
  } catch (error) {
    return { status: 'unhealthy', error: error.message };
  }
}

Data Flow Diagram

User Request
     │
     ▼
┌─────────────┐
│   API       │
│   Gateway   │
└──────┬──────┘
       │
       ▼
┌─────────────┐    ┌─────────────┐
│   Service   │───▶│   Cache     │
│   Layer     │    │   (Redis)   │
└──────┬──────┘    └─────────────┘
       │
       ▼
┌─────────────┐
│ Retell AI    │
│   Client    │
└──────┬──────┘
       │
       ▼
┌─────────────┐
│ Retell AI    │
│   API       │
└─────────────┘

Configuration Management

// config/retellai.ts
export interface Retell AIConfig {
  apiKey: string;
  environment: 'development' | 'staging' | 'production';
  timeout: number;
  retries: number;
  cache: {
    enabled: boolean;
    ttlSeconds: number;
  };
}

export function loadRetell AIConfig(): Retell AIConfig {
  const env = process.env.NODE_ENV || 'development';
  return require(`./retellai.${env}.json`);
}

Instructions

Step 1: Create Directory Structure

Set up the project layout following the reference structure above.

Step 2: Implement Client Wrapper

Create the singleton client with caching and monitoring.

Step 3: Add Error Handling

Implement custom error classes for Retell AI operations.

Step 4: Configure Health Checks

Add health check endpoint for Retell AI connectivity.

Output

Structured project layout
Client wrapper with caching
Error boundary implemented
Health checks configured

Error Handling

| Issue | Cause | Solution | |-------|-------|----------| | Circular dependencies | Wrong layering | Separate concerns by layer | | Config not loading | Wrong paths | Verify config file locations | | Type errors | Missing types | Add Retell AI types | | Test isolation | Shared state | Use dependency injection |

Examples

Quick Setup Script

# Create reference structure
mkdir -p src/retellai/{handlers} src/services/retellai src/api/retellai
touch src/retellai/{client,config,types,errors}.ts
touch src/services/retellai/{index,sync,cache}.ts

Resources

Flagship Skills

For multi-environment setup, see retellai-multi-env-setup.