Sandbox Templates

A Sandbox Template is reusable, versioned configuration for filesystem and compute. A new Session pins one immutable template revision into its primary Sandbox. The Sandbox is the durable logical resource; its physical Daytona instance or other provider compute may be replaced without changing the Session or Sandbox identity.

Sandbox Templates and Harnesses are separate. A Harness defines behavior and may fix the Sandbox policy or let an Agent offer template bindings. A template selects Bashkit, Daytona, or another execution target without changing the ordinary shell and file tools the model uses.

Create a Sandbox Template

1. Open Sandbox Templates and select New Sandbox Template.
2. Give it a stable name and display name.
3. Select Bashkit or an available managed provider such as Daytona.
4. Configure durability, lifecycle, and bootstrap options, then save.

Editing a Sandbox Template creates a new immutable revision. Existing Agent versions and Sessions keep the revision they already reference. Managed templates such as Bashkit Virtual Workspace are provisioned by Everruns and cannot be edited or archived.

Configure an Agent

1. Open Agents, then open the Agent.
2. Under More, select Primary sandbox.
3. Add a Sandbox Template. The Agent stores its exact revision, not a moving pointer.
4. Choose the policy mode:
   • Fixed: every Session gets the single configured Sandbox; Session overrides are rejected.
   • Selectable: Playground can select one of the Agent’s declared template bindings.
   • Configurable: Playground may also submit constrained one-off configuration.
5. Choose the default binding when the policy permits multiple choices.
6. Select Done, then Save changes.

Bashkit is available without a provider connection. Daytona is shown as unavailable when its integration is not installed. A user who starts a Daytona Session also needs a Daytona connection under Settings → My agent experience. Do not put credentials in target options or bootstrap commands; use connection management instead.

The built-in Bashkit Worker seals the primary Sandbox to Everruns’ managed Bashkit template. Agents based on it cannot change the policy, and Session creation cannot override it. Use provider-neutral Worker or Worker Base when an Agent must select Daytona or another target.

Start a Playground Session

1. Open Playground and start a new Session.
2. Select the Agent.
3. For a selectable or configurable Agent, select an allowed Sandbox. A fixed Agent shows the resolved Sandbox as read-only.
4. Select Start Playground chat.

The Session pins the resolved specification. Editing the Agent or Sandbox Template later affects new Sessions only. Open the Session’s Workspace tab to inspect the primary Sandbox ID, pinned template revision, target, containment, capabilities, recovery class, generation, and lifecycle state.

Recovery after compute loss

A checkpointed Sandbox separates durable workspace state from replaceable physical compute. Everruns checkpoints successful mutations. If a Daytona instance disappears, the next sandbox operation creates replacement compute, restores the workspace, and continues the same Session.

Files under the managed workspace survive replacement. Running processes, open terminals, and in-memory process state do not.

API

Create a reusable template:

POST /v1/sandbox-templates
{
  "name": "daytona-build",
  "display_name": "Daytona Build",
  "spec": {
    "target": { "kind": "managed", "provider": "daytona" },
    "durability": "checkpointed"
  }
}

Bind exact revisions to an Agent:

{
  "sandbox_policy": {
    "mode": "selectable",
    "default": "scratch",
    "templates": {
      "scratch": {
        "template_revision_id": "sbxtplrev_...",
        "target": { "kind": "vfs", "provider": "bashkit" }
      },
      "build": {
        "template_revision_id": "sbxtplrev_...",
        "target": { "kind": "managed", "provider": "daytona" },
        "durability": "checkpointed"
      }
    }
  }
}

Select a declared binding in Playground when the mode is selectable or configurable:

{
  "agent_id": "agent_...",
  "sandbox": { "use": "build" }
}

Use GET /v1/sandbox-targets to discover available targets, GET /v1/sessions/{session_id}/sandbox to inspect the resolved Sandbox, and GET /v1/sandbox-templates to list reusable templates.

Resource Sandbox fleets

The primary Sandbox is implicit: ordinary shell and file tools always address it. An Agent with the sandbox_fleet capability can additionally create explicitly addressed resource Sandboxes through sandbox_create, then use sandbox_exec, sandbox_read_file, sandbox_write_file, sandbox_inspect, sandbox_checkpoint, and sandbox_manage. Fleet operations never change where ordinary shell or file tools run.