Vercel released Workflow SDK 5 with regional runs and encrypted step state

Vercel released Workflow SDK 5. The announcement is on the Vercel blog under the byline of Pranay Prakash and Peter Wielander, dated 12 November. The post names each change in the release and quotes Vercel's own measurements for the engine rewrite.

The SDK runs regular async JavaScript and keeps it running through crashes, deployments and long waits, Vercel says. Vercel reports more than 4 billion steps and 700 million runs across earlier versions. The company groups the usage into two patterns: automation workflows that move data, and agents and harnesses.

What is in version 5

The engine is rewritten. Vercel reports p75 step-to-step overhead fell from 618 ms to 109 ms in internal benchmarks. Over 1,020 steps, late-run overhead was 25 times lower, Vercel says. Median stream delivery dropped from 226.1 seconds to 53.5 seconds. The company describes the gains as 1.6 times to 25 times improvements across measured workloads.

Workflow and step inputs and outputs are now encrypted. Hook payloads and stream data are also encrypted. The algorithm is AES-256-GCM. The key is unique per run. On Vercel, encryption needs no setup and no code changes, by the company's account. A payload retention option can delete sensitive data at the end of a run.

Regional runs replace the single-region model

Earlier versions ran workflows out of one region. Version 5 runs them in every Vercel Function region. A run has its own home region, Vercel says: its state, queue dispatch and streams stay there from the moment it starts. The company says this cuts the geographic distance between a workflow step and the service it calls.

Three packages aimed at agents

Vercel named three packages that sit on top of the SDK. @ai-sdk/workflow carries WorkflowAgent, a durable AI SDK agent loop. durable-harness wraps existing agent harnesses, named as Pi, OpenCode, Claude Code and Codex. eve builds agents with durable sessions on the SDK.

The post says v5 arrives with no major breaking changes and points at a separate upgrade guide. It does not give a deprecation date for v4 or a pricing change.

An AI engineering team already on Vercel gets the encryption, regional runs and the new engine with no code change. That is what the company's own account says. A team on different infrastructure can read the benchmarks as a floor. What is the p75 step-to-step overhead on the queue you wrote? The agent packages are the part worth watching. A durable wrapper that survives a deploy mid-run is a thing teams rebuild badly in-house.

Source

Primary source: Workflow SDK 5: built for production on the Vercel blog.