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This is an optional extension of the Running Agents on Sandboxes tutorial. Complete the main tutorial first.
The starter image is used when you start a devbox without specifying an image, and as the default base when you build a blueprint without providing Dockerfile content. It includes:
  • Core tools: jq, sudo
  • Extras: dnsutils, iputils-ping, less, vim, rsync, gh
  • Python stack: Python 3.12, pip, uv
  • Node stack: Node 22.15.0, npm, Yarn 1.22.22 via corepack

Overview

Instead of just pushing code changes, you can start a Next.js development server and create a tunnel to share a live preview link in your pull request. This allows reviewers to see the changes in action before merging.
1

Install dependencies and start the dev server

Install the project dependencies and start a Next.js development server. Make sure to bind to 0.0.0.0 so the tunnel can access it from outside the devbox.
2

Enable a tunnel to the dev server

Enable a tunnel on the Devbox to access port 3000 where the Next.js dev server is running. This will give you a public URL that you can share.
3

Post the preview link to the PR

Post the preview URL as a comment on your pull request so reviewers can view the changes live.
The tunnel URL will remain active as long as the devbox is running. Reviewers can click the link to see your changes in real-time. If you suspend the devbox, the tunnel will be unavailable until you resume it and re-enable the tunnel.

Next Steps