Vercel's Cursor Sandbox changelog is a useful execution-boundary signal for coding agents. The primary source says Cursor Cloud Agents can now run in Vercel Sandbox instead of Cursor's hosted machines, while Cursor continues to manage the agent harness and inference loop.
The mechanism is splitting the agent brain from the worker environment. Vercel says Cursor's Self-Hosted Machines APIs let customers supply the execution environment where agents clone repositories, edit files, and run commands and tests. Vercel Sandbox then provides an isolated Firecracker microVM for each agent request, with Vercel Functions and Vercel Workflow acting as a durable control plane that claims queued requests, provisions workers, monitors sessions, and cleans up automatically.
The immediate implication is that managed agent products are starting to compete on execution substrate, not only on model quality or IDE integration. The evidence boundary is Vercel's changelog and guide-level framing; it documents the architecture and claimed benefits, but not production reliability across customer fleets. Watch whether vendors expose enough policy, logging, credential scoping, and cleanup guarantees for these sandboxes to become default enterprise agent infrastructure.