Swap LLM backends without rebuilding your React chat UI

What it does

Provides a set of composable React components—Thread, Message, Composer, ActionBar, and others—that handle the tedious parts of a modern chat interface. You get streaming message rendering, auto-scroll, markdown, code highlighting, voice dictation, and keyboard shortcuts out of the box while keeping full control over styling. It also supports “generative UI,” where tool calls and JSON responses render as live React components and can pause for inline human approval.

The interesting bit

The runtime layer is deliberately backend-agnostic. The same UI primitives talk to Vercel AI SDK, LangGraph, LangChain, AG-UI, Google ADK, or a plain HTTP stream via swappable adapters. The README also notes ports for React Native and terminal (Ink), suggesting the core architecture isn’t married to the DOM.

Key highlights

• Radix-style composable primitives rather than a single monolithic chat widget
• CLI scaffolds a Next.js starter or drops a shadcn/ui theme into an existing codebase
• Generative UI: tool calls render as React components with human-in-the-loop approvals
• Typed end-to-end, from runtime APIs to message parts and tool schemas
• Backend packages for Vercel AI SDK, LangGraph, A2A, OpenCode, and custom data streams

Verdict

Worth evaluating if you’re building a serious AI chat product in React and are tired of reimplementing message lists. Skip it if your chat needs are a single input box and a static response.