Try the CopilotKit demo

Try examples/copilotkit for a React UI using the same Harnest graph on ADK and LangGraph. This deterministic demo needs no model key.

Prerequisites

Use Python 3.11 or newer, Node.js 22 with npm, and a checkout of Harnest. Activate your Python environment before installing the dependencies. Ports 5173, 1910, and 1911 must be free.

Start the demo

From the Harnest repository root, install the Python framework extras in your environment, then start the demo:

python -m pip install -e ".[all]"
cd examples/copilotkit
npm ci
HARNEST_PYTHON="$(command -v python)" npm run dev

Open http://127.0.0.1:5173. The launcher keeps the UI and both local agent servers together; Ctrl+C stops them. Ports 5173, 1910 and 1911 must be available. Sessions use in-memory storage and reset when the backend restarts.

Try the flows

Try	What you can verify
Conversation or type a message	Progress and replies stream through CopilotKit; the shared turn count updates
Browser tool	Harnest requests `set_accent`; CopilotKit changes the page and returns the result before the agent continues
Human approval	Approve or decline a fictional publication through CopilotKit’s standard interrupt UI
Error recovery	A failed run appears in the UI; the next message can still succeed
Type `slow`, then Stop run	Cancel the active request and start another turn
New conversation	Start a fresh thread with independent state

Run the checks

To repeat the real-browser checks, run these commands from examples/copilotkit:

npx playwright install chromium
HARNEST_PYTHON="$(command -v python)" npm test
npm run build

The browser suite tests one complete journey per framework and starts the demo if needed. No hosted CopilotKit account or separate runtime is required.

How it connects

The UI uses CopilotKit’s open-source React components and HttpAgent to send requests through the local Vite proxy to each backend’s /agui route. Harnest compiles the same authored graph for both frameworks. Browser handlers run frontend tools; approval controls return the interrupt decision. The demo validates Harnest’s AG-UI transport without model variability. Replace the deterministic agent with your own agent when integrating your application; see Connect a client, Share state and context, and Handle interactions.

Overview

Get started

Harnest Studio

Guides

API reference

Try the CopilotKit demo

Prerequisites

Start the demo

Try the flows

Run the checks

How it connects

​Prerequisites

​Start the demo

​Try the flows

​Run the checks

​How it connects

Prerequisites

Start the demo

Try the flows

Run the checks

How it connects