Workflow SDK 5: built for production

Vercel released Workflow SDK 5, which encrypts every payload end to end before it leaves your code. The event log stores step arguments and return values so a run can recover after a crash or deployment. That data can include customer information, model context, credentials, and tool-call results.

Workflow and step inputs and outputs, hook payloads, and stream data are encrypted with AES-256-GCM, using a unique key for each run. With encryption enabled, any Workflow SDK backend, Vercel included, only sees and stores ciphertext. Plaintext is decrypted in your deployment or in authorized observability tools.

On Vercel there's nothing to set up and your workflow code stays the same. Each run's key is derived from a key scoped to the deployment that created it, so a run can only decrypt its own data.

Vercel also says Workflow has handled more than 4 billion steps and 700 million runs, mostly automation like order processing and ETL pipelines, plus long-running agents. For the agent side, there's an experimental guide to running Claude Code in a Vercel Sandbox, driven by a Vercel Function. The session lives in a durable log, so a crashed turn resumes on a new function.