Environments & previews

Live previews

Every computer exposes a single preview URL on port 443, mapped to whichever port your dev server listens on (defaults to 3000). The URL is stable for the life of the computer and shareable with anyone you trust.

Previews work for any framework — Next.js, Vite, Remix, Express, FastAPI, Rails — anything that binds to a TCP port. If your app needs a different port, set it in Project settings → Previews.

Editor & terminal

We host a full editor and a real terminal for every computer. Use them to inspect the agent's changes, run commands by hand, debug failing tests, or take over a task entirely. Hosted VS Code is also available on a separate route.

Environment variables

Project-scoped environment variables are injected into every computer in the project. Set them in Project settings → Environment. Values are encrypted at rest and never shown to the agent in plaintext — the agent only sees a hint that a given variable exists.

When the agent finishes a turn, its final response includes an Environment Variables section listing any new env vars the code expects, so you know what to set before the next run.

Background services

For workers, queues, websocket servers, and other long-lived processes that don't serve HTTP, grasscoding supports background-service markers. Mark a service in your project and the agent will keep it running across turns and re-emit the marker on later runs so it stays synchronized.

SSH access

Each computer can be reached over SSH. Useful when you want to debug the environment yourself or run something the agent doesn't need to know about. Find SSH details in Project settings → Sandbox.

Cloning environments

Click Clone on any computer to get a brand-new VM with the same files, env vars, and install state. Cloning is how you safely run experiments without polluting your main working environment, and how you spin up parallel agents on the same project.