Lightcone Documentation

Northstar is a vision-language model trained with reinforcement learning to operate computers. It looks at a screenshot, decides what to do — click, type, scroll, navigate — and acts. Give it a task in plain language and it works through it step by step, the same way a human would.

Lightcone is the API and runtime for Northstar. You describe what you want done, Northstar does it.

The Lightcone API and SDK are in beta. APIs, parameters, and behavior are subject to change. We recommend updating to the latest SDK version as new releases come out. If you have questions or run into issues, contact support@tzafon.ai.

Get started

Quickstart	Get Northstar running a task in under 5 minutes
Authentication	Get your API key and configure the SDK
How Lightcone works	Architecture, models, and the API layers
API Reference	Full reference for all endpoints

Choose your path

I want Northstar to do work for me

Describe a task in plain language. Northstar operates a computer to complete it — opening apps, filling forms, navigating between pages. Stream progress in real time.

• Tasks — start, monitor, pause, and resume work
• Run a task — streaming, polling, and steering

I want to build my own computer-use loop

Use the Responses API to build a multi-turn loop. Northstar looks at a screenshot, tells you what action to take, you execute it, feed back the new screenshot. You control the loop and can inject custom logic between steps.

• Responses API — create responses, process actions, chain turns
• Computer-use loop — full implementation guide

I want to control a computer programmatically (no model)

Create a cloud computer and send actions directly — click, type, scroll, navigate, screenshot, shell commands. No model involved.

• Computers — create, interact with, and manage cloud computers
• Operate a computer — end-to-end walkthrough

I want text generation / Chat Completions

OpenAI-compatible Chat Completions with tool calling, streaming, and structured outputs. Drop-in replacement — just change the base URL.

• Chat Completions — usage, streaming, tool calling, models

Use cases

Use case	What it does
Software testing	Northstar tests your app like a real user — no selectors, no scripts to maintain
Legacy software automation	Northstar operates enterprise software through the GUI — no API required
Cross-application workflows	Northstar moves data between apps that don’t talk to each other

Integrations

Lightcone works with the tools you already use.

LangChain	CrewAI	Browser-Use
Vercel AI SDK	Mastra	MCP Server
Playwright

View all integrations

Install the SDK

pip install tzafon

npm install @tzafon/lightcone

Having trouble? See the Troubleshooting guide.