Vercel Sandbox swaps its runtimes for versioned open-source base images with coding agents preinstalled

Vercel's changelog entry of 10 August 2026 makes Vercel Managed Images the default for Vercel Sandbox, replacing the previous Sandbox runtimes: versioned, open-source base images that already carry Node.js, Python and coding agents. The same week Vercel also brought `vercel connect create` to the terminal for all 100-plus preset connectors (11 August) and made Bun.serve() a valid entrypoint for Vercel Functions, including native WebSocket handlers.

What it means A pinned, inspectable image is the difference between an agent sandbox you can reproduce and one you can only describe — worth a look before your next "it worked yesterday" agent incident.