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Build reliable, long-running processes with automatic retries, state persistence, and observability built in.

server.ts

import { RetryableError, FatalError } from "workflow";async function callAPI(endpoint) {  "use step";  const response = await fetch(endpoint);  if (response.status >= 500) {    // Uncaught exceptions are retried by default    throw new Error("Server error");  }  if (response.status === 404) {    // Explicitly throw a FatalError to skip retrying    throw new FatalError("Resource not found. Skipping retries.");  }  if (response.status === 429) {    const retryAfter = response.headers.get('Retry-After');    // Customize the duration before retrying    throw new RetryableError("Too many requests. Retrying...", {      retryAfter: parseInt(retryAfter)    });  }  return response.json();}// Customize max retrieschargeCard.maxRetries = 5;