Hooks run shell commands at points in a sandbox’s lifecycle. They’re how you install dependencies, select a runtime, or do any one-time setup so the agent starts from a ready-to-work environment.
SandboxReady
SandboxReady is the hook that runs once the sandbox is up and your repository
is checked out — before preview processes start. Provide an array of commands;
they run in order.
{
"hooks": {
"SandboxReady": [
{ "command": "source /usr/local/share/nvm/nvm.sh && nvm use 24" },
{ "command": "bun install" }
]
}
}Each entry is an object with a command string. Commands run in your
repository’s working directory.
What to put here
- Install dependencies —
bun install,npm ci,pip install -r requirements.txt, etc. - Select a runtime/toolchain — e.g. activate a Node version.
- One-time setup — generate code, prepare a database schema, seed fixtures.