# Sandbox Worker Harness

> Worker plus a full sandbox shell, for agents that need real processes, packages and builds.

Source: <https://everruns.com/docs/built-ins/harnesses/sandbox-worker/>

**Sandbox Worker** extends [Worker](https://everruns.com/docs/built-ins/harnesses/worker/) and requires a full sandbox: a container or a managed provider such as Daytona, E2B or Modal. The Agent’s Sandbox policy chooses which one.

|                     |                                                             |
| ------------------- | ----------------------------------------------------------- |
| **Name**            | `sandbox-worker`                                            |
| **Parent**          | `worker`                                                    |
| **Sandbox policy**  | Required; must name a container or managed Sandbox Template |
| **Primary Sandbox** | Whatever the Agent’s policy selects                         |

Use it for coding agents, data work that installs packages, browser automation and long builds. The [Coding](https://everruns.com/docs/how-to/customize-a-harness/) harness example builds on it.

Sandbox Worker never falls back to Bashkit:

* Saving an Agent whose Sandbox policy can only resolve to Bashkit is rejected.
* An Agent with no Sandbox policy saves, but starting a Session on it fails with a message that names the missing policy.

Choose [Bashkit Worker](https://everruns.com/docs/built-ins/harnesses/bashkit-worker/) for a virtual shell that needs no provider. Custom Harnesses that inherit from Sandbox Worker inherit the requirement too.

Sandbox Worker is a Platform harness. In the Framework, express the same need as an Environment requirement on your harness and bind an Environment that provides it.

See [Sandbox Templates](https://everruns.com/docs/features/sandbox-templates/) for configuring providers.