Workflow SDK v5.2.0 writes events and streams over WebSockets on Vercel by default
The Workflow SDK now sends event writes and stream writes over a WebSocket by default, replacing one HTTP request per write (or per write group for streams). No code change is required beyond upgrading to workflow@5.2.0 or later. In a benchmark replaying an AI agent's token stream, v5.2.0 delivered the full response 4.2× faster than v4.8.12, with no chunk delayed over a second.
Why it matters
Workflows with many steps make fewer HTTP requests, and streamed AI output such as tokens reaches clients faster. The changelog states the efficiency also improves performance and reduces costs. New runs use the upgrade after deployment, while in-flight runs finish on the deployment they started on.
Who should care
Developers running durable workflows or AI agents on Vercel Workflow, especially those streaming AI model output.
What you can do
Upgrade to workflow@5.2.0 or later, deploy, and rerun a streaming workflow to measure the difference in token delivery time.