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Introduction

Curb

Curb is a React framework for production voice agents. You write the agent as a tree of components, and Curb renders that tree into what the model gets on each turn: its context and its tools. When your state changes, the next request changes with it. A tool your code does not render is not in the request, so the model cannot call it.

Curb also runs the rest of the call: speech to text, text to speech, turn-taking and interruptions, a browser preview, and a test runner that plays whole conversations with no microphone.

How to use the docs

The docs have four parts:

  • Getting Started: read in order. It takes you from an empty folder to a deployed insurance agent, one feature at a time.
  • Guides: one task per page, such as handing a call to a person. Read the one you need.
  • Concepts: how Curb works underneath, for when you want the full picture.
  • API Reference: every component, hook, function, provider, command and setting.

Press / to search, or read any page as Markdown from the link beside it. For a coding agent, llms.txt lists every page, and the same guide ships inside the curb package at node_modules/curb/docs/agent-guide/, matched to the installed version.

What you should know first

The docs assume you know React and TypeScript. You do not need to know anything about speech: Curb runs that part, and the Voice page shows what you can change.

You need Node.js 22.12 or newer. A new project runs on KugelAudio with one sign-in. You can use other providers for every part of the pipeline, and you can host the agent yourself.

The core idea

export default function ReportClaim() {
  const [verified, setVerified] = useState(false);
  if (!verified) return <>
    <Instruction>Ask for the policy number.</Instruction>
    <Tool name="verify_policy" … />
  </>;
  return <>
    <Instruction>Ask what happened.</Instruction>
    <Tool name="open_claim" … />
  </>;
}

Until the policy is verified, open_claim does not exist for the model, whatever the caller says. What the model receives shows the real requests.

Next steps