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Sandbox

Quirks, env vars, and debugging tips for code running inside a Vendo customize sandbox.

When you customize a tool through the Vendo UI, your edits run inside a per-deployment customize sandbox. The sandbox sets a handful of env vars at boot, runs the SDK in Vendo mode, and exposes MCP servers to the customize agent.

If you're writing code that uses vendo_sdk or @vendodev/sdk inside that sandbox, the pages below cover the gotchas you'll hit and the env vars you can rely on.

Gotchas

The 10 things that bite agents writing SDK code in the sandbox.

Runtime env vars

Every env var the sandbox injects into your tool's processes.

Healthchecks

The contract Vendo uses to decide whether your deployment is alive — and what happens when it isn't.

Sandbox SDK gotchas

Read this before writing code that uses vendo_sdk inside a customize sandbox. Most "Loading..." spirals trace back to one of the items below.