Vercel AI SDK 6: Agents Promoted to First-Class Abstraction with ToolLoopAgent, Single-Flag HITL (needsApproval), and Native SSE Streaming

Vercel·medium signal

AI SDK 6 introduces the Agent interface and ToolLoopAgent default implementation — define once, use across the app with full end-to-end type safety and up to 20 tool execution steps per loop. Human-in-the-loop control requires only a needsApproval flag, no custom scaffolding. Streaming migrates to native SSE, eliminating custom wire formats and making agent communication debuggable with browser dev tools. Positions Vercel as the production-grade TypeScript agent runtime for Next.js developers who need agent patterns without framework fragmentation.