Sandbox Stable

# Sandbox SDK — stable package

Isolated Linux environments on [Cloudflare Containers](https://developers.cloudflare.com/containers/index.md), driven from Workers.

**Prefer the main Sandbox docs and installed stable types over memory.** This skill is a gate, a contract, and a retrieval map—not a full manual.

This line is the **current stable** default npm package. The main [Sandbox documentation](https://developers.cloudflare.com/sandbox/index.md) describes it. Existing apps can stay here and keep shipping.

We recommend **new projects** on `@cloudflare/sandbox@next` with **`sandbox-next`**. When you can, plan a move with **`sandbox-migrate-to-next`** so you are ready when 1.0 becomes the stable release. Do not force that port unless the user asks.

## 1. Gate — confirm the package line

Before writing code, inspect the app:

| Check | Must match | | ----- | ---------- | | npm dependency | Default `@cloudflare/sandbox` (**not** `@next` / preview tags) | | Container image | Matching **stable** image (not `cloudflare/sandbox:next`) |

| If you find… | Action | | ------------ | ------ | | `@cloudflare/sandbox@next` or a `next` image | **Stop.** Load **`sandbox-next`**. | | User wants to port to 1.0 / `@next` | **Stop.** Load **`sandbox-migrate-to-next`**. Do not half-apply preview APIs on a stable package. | | Only cleaning deprecated stable APIs | Stay here; use the [2026 deprecation guide](https://developers.cloudflare.com/sandbox/sdk/migrate/index.md). That is **not** a move to `@next`. |

Never mix a stable Worker package with an `@next` container image (or the reverse).

Skills install: [Agent setup](https://developers.cloudflare.com/agent-setup/index.md) · [cloudflare/skills](https://github.com/cloudflare/skills)

## 2. Contract — non-negotiables

- `await sandbox.exec(command)` takes a **command string** and resolves when the command **finishes**, with buffered `stdout` / `stderr` / `exitCode` (and related fields). - Long-running and streaming work use the **stable** command APIs (`startProcess`, `execStream`, and related helpers)—not the `@next` single-handle model. Open the Commands docs; do not invent `@next` `output()` handles on stable. - **Sessions** can preserve working directory and environment across commands (default session / `enableDefaultSession`, `createSession`). See Sessions docs when state must carry across calls. - Interactive browser terminals often use **`sandbox.terminal(request)`** and session/xterm helpers on stable—not preview `createTerminal` unless the package is `@next`. - Prefer **RPC** transport when using tunnels or large/binary streaming. HTTP/WebSocket transports are deprecated (cleanup guide below). - Files, mounts, ports, tunnels, backups, lifecycle, and interpreter: use main docs for signatures; trust installed **stable** types. - Non-secret config in sandbox env; live credentials in the Worker. Use outbound handlers when processes call external APIs. - Production preview hostnames need wildcard DNS on a custom domain when using those URL patterns. - Do **not** apply `@next` argv/`process.output()` APIs while the dependency is still stable. - Self-deployed **bridge** stays on the stable package and image. [Bridge](https://developers.cloudflare.com/sandbox/sdk/bridge/index.md)

Minimal shape:

```ts import { getSandbox, proxyToSandbox, Sandbox } from "@cloudflare/sandbox";

export { Sandbox };

const sandbox = getSandbox(env.Sandbox, "user-123"); const result = await sandbox.exec('python3 -c "print(2 + 2)"'); // result.stdout, result.exitCode, result.success ```

## 3. Retrieve — open the doc for the task

Fetch the page before implementing. Installed stable types win over guesses.

| You need to… | Open | | ------------ | ---- | | Orient | [Sandbox overview](https://developers.cloudflare.com/sandbox/index.md) | | First Worker, template, Docker | [Get started](https://developers.cloudflare.com/sandbox/get-started/index.md) | | `exec`, streaming, background processes | [Commands API](https://developers.cloudflare.com/sandbox/sdk/api/commands/index.md) · [Execute commands](https://developers.cloudflare.com/sandbox/sdk/guides/execute-commands/index.md) · [Background processes](https://developers.cloudflare.com/sandbox/sdk/guides/background-processes/index.md) · [Streaming output](https://developers.cloudflare.com/sandbox/sdk/guides/streaming-output/index.md) | | Sessions / shell state across commands | [Sessions concept](https://developers.cloudflare.com/sandbox/sdk/concepts/sessions/index.md) · [Sessions API](https://developers.cloudflare.com/sandbox/sdk/api/sessions/index.md) | | `getSandbox` options, sleep, destroy | [Lifecycle API](https://developers.cloudflare.com/sandbox/sdk/api/lifecycle/index.md) · [Sandbox options](https://developers.cloudflare.com/sandbox/sdk/configuration/sandbox-options/index.md) | | Env vars | [Environment variables](https://developers.cloudflare.com/sandbox/sdk/configuration/environment-variables/index.md) | | Files | [Files API](https://d