Vercel AI Updates: July 29, 2026

1. Vercel Sandbox Adds Forking For Agent Branching

Vercel. Vercel added a Sandbox.fork() method that creates an independent copy of an existing sandbox, starting from the source’s current snapshot and inheriting its config and environment variables. The feature targets agent branching, multi-tenant deployments, and parallel testing, so teams can define a shared baseline and quickly spin up variations for different AI agent instances or workloads. Forking takes roughly as long as creating a new sandbox from scratch. Source

2. AI SDK Workflow Package Gains Dynamic Tool Descriptions

Vercel. The AI SDK Workflow package reached version 1.0.39 on July 28, adding support for dynamic tool descriptions and the ability to stream instructions and initial prepareStep inputs, along with prepareCall setting parity. The companion workflow-harness release added utility functions for defining agent-step based workflows, giving developers more control over how multi-step agents are configured and executed. Source

3. Sandstone Scales Legal AI Agents On The AI SDK

Vercel. Vercel published a case study on legal-tech startup Sandstone, which built agentic workflows on the AI SDK that search agreements, surface at-risk items, and send Slack notifications, alongside the Chat SDK and Flags SDK. The company reported 40x revenue growth in under six months, more than 1,000 legal requests handled daily across customer teams, and a $30M Series A led by Lightspeed. The account illustrates how teams compose multiple AI SDK primitives to ship agent-driven products quickly. Source