The best workflow engine is a programming language

This post introduces the Workflow SDK, an open-source library that enables writing durable workflows in TypeScript using familiar programming language constructs. It replaces traditional workflow engines by treating code itself as a Directed Acyclic Graph (DAG). Key contributions include: 1. A 'use workflow' and 'use step' directive system for defining workflow orchestrators and side-effecting units of work. 2. Automatic retries for steps with configurable error handling (FatalError, RetryableError). 3. A unified 'hook' primitive that replaces Temporal's signals, queries, and updates, simplifying inter-workflow communication and external interaction via ad-hoc webhooks. 4. A swappable backend architecture ('World') allowing integration with various storage (Postgres, Turso, Durable Objects) and queuing systems (Vercel Queues, SQS). 5. A Vercel-specific versioning strategy that pins runs to the starting deployment, simplifying in-flight workflow evolution. 6. A stated goal of minimizing step overhead to make them feel 'free'.