A compact Next.js example showing how to build a custom CopilotKit chat UI with ShadCN-style primitives. It uses useAgent with a CopilotKit Built-in Agent at /api/copilotkit, renders assistant messages with local chat components, and includes two frontend interactions:

A generated line chart rendered through useFrontendTool
A human-in-the-loop taco rain picker rendered through useHumanInTheLoop

The app intentionally keeps the chat prompt fixed to make the demo repeatable.

Prerequisites

Node.js 20 or newer
pnpm, via Corepack or your local install. The example declares pnpm@10.33.4 in package.json.
An OpenAI API key

Environment Variables

Create a local environment file:

cp .env.example .env.local

Then set:

OPENAI_API_KEY=sk-...
COPILOTKIT_MODEL=openai/gpt-5.4

OPENAI_API_KEY is required for the Built-in Agent. COPILOTKIT_MODEL is optional and defaults to openai/gpt-5.4 in app/api/copilotkit/route.ts.

Setup

From this example directory:

cd examples/shadcn
corepack enable
pnpm install
pnpm dev

Open the local URL printed by Next.js, usually http://localhost:3000.

Try It

Press the send button to run each queued example:

Ask for a brief explanation of ShadCN
Render a simple generated line chart
Open the taco rain picker, choose an emoji, and make it rain

Use the reset button in the chat header to replay the sequence.

Available Checks

pnpm typecheck
pnpm lint
pnpm build

pnpm check-types is also available as an alias for pnpm typecheck.