sandbox-next

Sandbox SDK —

@next

(1.0 preview)

Isolated Linux environments on Cloudflare Containers, driven from Workers.

Prefer preview docs and installed
@next
types over memory. APIs change; this skill is a gate, a contract, and a retrieval map—not a full manual.

We recommend new projects on this line. Apps still on the default package use sandbox-stable
. Port only when asked, via sandbox-migrate-to-next
.

1. Gate — confirm the package line

Before writing code, inspect the app:

Check	Must match
npm dependency	`@cloudflare/sandbox@next` (or another preview tag)
Container image	Same line (e.g. `cloudflare/sandbox:next` , `next-python` )

If you find…	Action
Default `@cloudflare/sandbox` (no `@next` )	Stop. Load `sandbox-stable` . Do not apply this skill’s APIs.
User wants to port stable → `@next`	Stop. Load `sandbox-migrate-to-next` .
Self-deployed bridge only	Bridge is not on the 1.0 preview line yet. Keep bridge on stable package + image. Bridge (stable)

Never mix an

@next

Worker package with a stable container image (or the reverse).

Skills install: Agent setup · cloudflare/skills

2. Contract — non-negotiables

```
sandbox.exec(argv)
```
takes an argv list and resolves when the process starts. It returns a handle, not a finished command result.

Collect results with handle methods:

output()

logs()

waitForExit()

waitForPort()

waitForLog()

kill(signal?)

No implicit shell. Shell syntax needs an explicit shell, e.g.
```
["/bin/bash", "-lc", script]
```
.
Each launch is independent. A
```
cd
```
/
```
export
```
in one
```
exec
```
is not visible to the next. Pass
```
cwd
```
and
```
env
```
per launch, or one shell script.
Process handles have no stdin. Interactive use → terminals (
```
createTerminal
```
+
```
connect
```
).
Local wait
```
timeout
```
/
```
AbortSignal
```
cancel the wait only. They do not kill the process. Use
```
kill
```
or
```
exec
```
’s remote
```
timeout
```
.
```
getProcess
```
/
```
listProcesses
```
/
```
getTerminal
```
/
```
listTerminals
```
do not start a container; they return
```
null
```
/
```
[]
```
when none is up.
Process and terminal IDs belong to the current container, not forever to a sandbox ID. For work that must survive replace, store the full job (argv, cwd, env, app state)—not only an id.
Non-secret config only in
```
setEnvVars
```
/ launch
```
env
```
. Live credentials stay in the Worker; use outbound handlers when the sandbox calls external APIs.
Do not invent removed stable APIs (
```
gitCheckout
```
on core, string-
```
exec
```
completion, session execution,
```
sandbox.terminal(request)
```
).
Do not use one retry loop for every error (see Errors docs).

Minimal shape:

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

export { Sandbox };

const sandbox = getSandbox(env.Sandbox, "user-123");
const process = await sandbox.exec(["python3", "-c", "print(2 + 2)"]);
const result = await process.output({ encoding: "utf8" });
// result.stdout, result.exitCode

Optional non-exhaustive cheatsheet (process/terminal/interpreter only): references/api-quick-ref.md
Examples index (

next

branch): references/examples.md

3. Retrieve — open the doc for the task

Fetch the page before implementing. Installed

@next

types win over guesses.

You need to…	Open
Orient / choose preview	1.0 preview overview
First Worker, wrangler, Dockerfile	Get started
`exec` , handles, readiness, durability	Process execution
Process API signatures	Processes API
Sandbox ID vs container vs sleep/destroy	Lifecycle
`cwd` / `env` / `setEnvVars`	Environment
Interactive PTY / browser terminal	Terminals · Terminals API
Python/JS code interpreter	Interpreter · Interpreter API
Extensions model	Extensions
Error classes and recovery	Errors · Errors API
Common failures	Troubleshooting
API hub	API reference
Files, mounts, backups, ports, tunnels, `proxyToSandbox`	Main docs for shared surfaces (ignore stable-only session/transport/ `sandbox.terminal` ): Files · Storage / mounts · Ports · Tunnels · Backups · Outbound traffic · Expose services · Production
Example apps	examples on `next`
Still on stable package	`sandbox-stable` · Main Sandbox docs
Porting an existing stable app	`sandbox-migrate-to-next` · Migrate

4. Before you ship

Lockfile and Dockerfile on the same
```
@next
```
line
Typecheck against installed
```
@next
```
types
No live secrets in sandbox env
Production preview hostnames need wildcard DNS on a custom domain when using those URL patterns

sandbox-next

NPX Install

Tags

SKILL.md Content

Sandbox SDK —
`@next`
(1.0 preview)

1. Gate — confirm the package line

2. Contract — non-negotiables

3. Retrieve — open the doc for the task

4. Before you ship