Model Fallback & Circuit Breaker

import { openai, anthropic, withFallback } from "@agentium/core";

const resilientModel = withFallback([
  openai("gpt-4o"),
  anthropic("claude-sonnet-4-20250514"),
  openai("gpt-4o-mini"),
]);

const agent = new Agent({
  name: "resilient-agent",
  model: resilientModel,
  instructions: "You are a helpful assistant.",
});

import { CircuitBreaker } from "@agentium/core";

const breaker = new CircuitBreaker({
  failureThreshold: 5,      // failures before opening
  cooldownMs: 30_000,       // time before half-open
  halfOpenMaxAttempts: 2,    // probes before closing
  classifyError: (error) => {
    // Custom error classification
    if (isRateLimit(error)) return "retry";
    if (isAuthError(error)) return "cascade";
    return "fatal";
  },
});

import { FallbackProvider, openai, anthropic, google } from "@agentium/core";

const provider = new FallbackProvider({
  providers: [
    openai("gpt-4o"),
    anthropic("claude-sonnet-4-20250514"),
    google("gemini-2.5-flash"),
  ],
  circuitBreaker: {
    failureThreshold: 3,
    cooldownMs: 60_000,
  },
  onFallback: (from, to, error) => {
    console.log(`Falling back from ${from} to ${to}: ${error}`);
  },
});