Durable, long-running workflows with automatic retries, state persistence, and event handling on Cloudflare Workers.

• Supports three core step types: step.do() for work execution with configurable retries, step.sleep() for delays, and step.waitForEvent() for external event handling with timeouts
• Automatically persists serializable state across steps and hibernation; prevents 12 documented errors including waitForEvent timeout bugs, I/O context violations, and non-idempotent operation pitfalls
• Includes Vitest testing with introspection API, mock step results, and event simulation; local dev limitations documented (instance lifecycle, getPlatformProxy incompatibility)
• Scales to 10,000 concurrent instances with 100 steps/second creation rate; sleeping instances don't count toward concurrency; pricing at $0.30 per million step executions after 10M free monthly