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

• Retell AI SDK Documentation
• Retell AI Best Practices

Flagship Skills

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