@lov3kaizen/agentsea-gateway

@lov3kaizen/agentsea-gateway

High-performance TypeScript-native LLM gateway with unified API access, intelligent routing, caching, and cost optimization.

Features

• Unified API: OpenAI-compatible API for all providers (OpenAI, Anthropic, Google)
• Intelligent Routing: Round-robin, failover, cost-optimized, and latency-optimized strategies
• Virtual Models: Use best, cheapest, or fastest to auto-route to optimal providers
• Caching: Built-in LRU cache to reduce costs and latency
• Streaming: Full streaming support with SSE
• Metrics: Request tracking, cost calculation, and latency monitoring
• Failover: Automatic retry with circuit breaker protection
• Type-Safe: Full TypeScript support with comprehensive types

Installation

pnpm add @lov3kaizen/agentsea-gateway

Quick Start

As HTTP Proxy

import {
  Gateway,
  createHTTPServer,
  startServer,
} from '@lov3kaizen/agentsea-gateway';

const gateway = new Gateway({
  providers: [
    {
      name: 'openai',
      apiKey: process.env.OPENAI_API_KEY,
      models: ['gpt-5.5', 'gpt-5.4-mini'],
    },
    {
      name: 'anthropic',
      apiKey: process.env.ANTHROPIC_API_KEY,
      models: ['claude-sonnet-4-6'],
    },
  ],
  routing: {
    strategy: 'cost-optimized',
  },
});

const app = createHTTPServer({ gateway });
startServer(app, { port: 3000 });

Then use it like the OpenAI API:

curl http://localhost:3000/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "cheapest",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

As SDK

import { Gateway } from '@lov3kaizen/agentsea-gateway';

const gateway = new Gateway({
  providers: [
    { name: 'openai', apiKey: process.env.OPENAI_API_KEY, models: ['gpt-5.5'] },
  ],
});

// OpenAI-compatible interface
const response = await gateway.chat.completions.create({
  model: 'gpt-5.5',
  messages: [{ role: 'user', content: 'Hello!' }],
});

console.log(response.choices[0].message.content);
console.log(response._gateway); // Gateway metadata (provider, cost, latency)

Virtual Models

Instead of specifying a model, use virtual models for automatic routing:

// Route to highest quality available model
await gateway.chat.completions.create({
  model: 'best',
  messages: [{ role: 'user', content: 'Complex reasoning task...' }],
});

// Route to cheapest model
await gateway.chat.completions.create({
  model: 'cheapest',
  messages: [{ role: 'user', content: 'Simple task...' }],
});

// Route to fastest provider
await gateway.chat.completions.create({
  model: 'fastest',
  messages: [{ role: 'user', content: 'Time-sensitive task...' }],
});

Routing Strategies

Round-Robin

Distributes requests evenly across providers:

const gateway = new Gateway({
  providers: [...],
  routing: {
    strategy: 'round-robin',
    weights: { openai: 2, anthropic: 1 }, // 2:1 ratio
  },
});

Failover

Tries providers in order until one succeeds:

const gateway = new Gateway({
  providers: [...],
  routing: {
    strategy: 'failover',
    fallbackChain: ['openai', 'anthropic', 'google'],
  },
});

Cost-Optimized

Selects the cheapest model meeting quality requirements:

import { CostOptimizedStrategy } from '@lov3kaizen/agentsea-gateway';

const gateway = new Gateway({
  providers: [...],
  routing: { strategy: 'cost-optimized' },
});

Latency-Optimized

Routes to the fastest provider based on observed latencies:

const gateway = new Gateway({
  providers: [...],
  routing: { strategy: 'latency-optimized' },
});

Caching

Enable caching to reduce costs and latency for repeated requests:

const gateway = new Gateway({
  providers: [...],
  cache: {
    enabled: true,
    ttl: 3600, // 1 hour
    maxEntries: 1000,
    type: 'exact', // Hash-based matching
  },
});

Request Metadata

Add gateway-specific options to requests:

const response = await gateway.chat.completions.create({
  model: 'gpt-5.5',
  messages: [...],
  _gateway: {
    preferredProvider: 'anthropic',
    excludeProviders: ['google'],
    maxCost: 0.01, // Max $0.01 per request
    maxLatency: 5000, // Max 5 seconds
    cachePolicy: 'no-cache', // Skip cache
    tags: { user: 'user-123' },
  },
});

Response Metadata

Every response includes gateway metadata:

const response = await gateway.chat.completions.create({ ... });

console.log(response._gateway);
// {
//   provider: 'openai',
//   originalModel: 'cheapest',
//   latencyMs: 1234,
//   cost: 0.000123,
//   cached: false,
//   retries: 0,
//   routingDecision: { ... }
// }

Streaming

Full streaming support:

const stream = await gateway.chat.completions.create({
  model: 'gpt-5.5',
  messages: [{ role: 'user', content: 'Tell me a story' }],
  stream: true,
});

for await (const chunk of stream) {
  process.stdout.write(chunk.choices[0]?.delta?.content || '');
}

Metrics

Track usage and costs:

const metrics = gateway.getMetrics();

console.log(metrics.requests.total);
console.log(metrics.cost.total);
console.log(metrics.cost.byProvider);
console.log(metrics.latency.avg);
console.log(metrics.cache.hitRate);

Events

Listen to gateway events:

gateway.on('request:complete', (event) => {
  console.log(`${event.provider}: ${event.latencyMs}ms, $${event.cost}`);
});

gateway.on('request:error', (event) => {
  console.error(`Error: ${event.error.message}`);
});

gateway.on('provider:unhealthy', (provider) => {
  console.warn(`Provider ${provider} is unhealthy`);
});

API Reference

Gateway

Main gateway class:

• constructor(config: GatewayConfig)
• chat.completions.create(request) - Create completion
• getMetrics() - Get usage metrics
• getRegistry() - Get provider registry
• getRouter() - Get router instance
• checkHealth() - Check provider health
• shutdown() - Clean shutdown

Providers

Built-in providers:

• OpenAIProvider - OpenAI/Azure OpenAI
• AnthropicProvider - Anthropic Claude
• GoogleProvider - Google Gemini

Routing Strategies

• RoundRobinStrategy - Even distribution
• FailoverStrategy - Ordered fallback
• CostOptimizedStrategy - Cheapest model
• LatencyOptimizedStrategy - Fastest provider

License

MIT