Vercel Chat SDK adds streaming generative UI via json-render
Vercel's changelog announced that Chat SDK agents can now stream generative UI using json-render. An agent writes a JSON spec built from a typed component catalog, which is converted into a Chat SDK card and posted in each platform's native format, such as Block Kit on Slack and Adaptive Cards on Teams. The stream updates the message at most once every 500 ms by default, and a validation function checks element props and platform limits.
Why it matters
Builders using Chat SDK can render tables, charts, and buttons in agent replies on multiple chat platforms without writing separate tooling per platform or per message shape. Platform limits are enforced by the adapters, and specs can be rejected rather than silently degraded.
Who should care
Developers building chat-based agents or bots on Slack, Teams, or other Chat SDK platforms; teams shipping conversational commerce or support assistants.
What you can do
Read the Chat SDK json-render documentation and try the playground, then wire streamCard and validation with the limits option into one existing agent reply.