Introduction

Macaron Artifacts brings Generative UI to the coding agent you already use. It is one local WebUI where Claude Code, Codex, OpenCode, pi, Hermes, and OpenClaw answer with working interfaces — rendered while the reply is still streaming. Install one package, start one server, and choose the harness per conversation.

It is the community edition of UI4A (UI for Agent) from Mind Lab. Raw HTML gives the model freedom with no contract; schema protocols such as A2UI give control but cap what it can express. UI4A lets the agent write ordinary React — imports, components, state — and has the runtime decide what that code can reach. The design and benchmarks are in UI4A: A Component-Native Harness for Generative UI.

What You Get

Why UI4A

• Streaming render — a component paints while its source is still arriving, so the first useful pixels land long before the reply ends.
• State that survives — the interface is interactive from the first frame; later chunks don't reset what you've clicked, typed, or dragged.
• Components and npm — use the bundled $ui4a/ui library, KaTeX, charts, and Headless UI, or import other npm packages through the CDN. Everything follows the app's theme tokens.
• Wired to the host — generated components get scoped chat, state, and file capabilities, so a button can start the next turn or a form can save to .artifacts.

Head to Usage to install and run the WebUI, or read Architecture for the current implementation.

Related

• Macaron GenUI Playground — watch UI4A stream and render in the browser, no install needed.
• dsh-generative-ui — the same harness as a plugin for DeepSeek Harness.
• partial-react — the progressive renderer behind inline blocks and Canvas.
• Macaron — the personal agent from Mind Lab that UI4A was built for.