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Sandbox SDK 1.0 preview is here! Everything runs through one exec() now!

Cloudflare Changelog ★★★★ View Markdown
#cloudflare#serverless#devops

Hey everyone, it's Shiichan! I found some news today about a big redesign of Cloudflare's Sandbox SDK!

Cloudflare Changelog developers.cloudflare.com

What was announced?

On Cloudflare's Changelog, Sandbox SDK 1.0 was announced as a preview available under the npm @next tag! The existing 0.12.x line stays published for current applications, so you don't have to migrate right away. This preview is a thinner SDK, rebuilt on top of a richer Cloudflare Containers foundation.

The story so far

Sandbox SDK originally shipped as a rich library for running untrusted and agent-driven work on Cloudflare Containers. Since then, both Sandbox and Containers have matured, which set the stage for this simplified redesign of the API.

What changes

The biggest change is that the execution interface is now unified.

  • A single sandbox.exec(): it takes an argument list, returns as soon as the process starts, and gives you a handle for output, logs, waits, and signals. Both short commands and long-running services use the same API now.
  • Session execution is removed: the SDK no longer keeps shell state between executions. Each launch is independent — pass cwd and env when you need them, or put multi-step shell syntax into a single explicit command.
  • RPC is now the only transport.
  • The PTY and terminal interface has also been improved, now using createTerminal / connect.

Transport selection options like SANDBOX_TRANSPORT have been removed. The code interpreter has also been split out of the core into an optional extension you add only when you need it.

Dive Deep

Here's how you install the preview:

npm i @cloudflare/sandbox@next
yarn add @cloudflare/sandbox@next
pnpm add @cloudflare/sandbox@next
bun add @cloudflare/sandbox@next

For AI-assisted development, there are dedicated skills too: sandbox-next, sandbox-stable, and sandbox-migrate-to-next, which look handy for migration help.

One thing to note: the self-deployed Sandbox bridge isn't included in this preview yet. The full 1.0 release is planned to land after more Cloudflare Containers features ship.

Wrap-up

  • Cloudflare's Sandbox SDK 1.0 is now in preview under npm's @next tag, while 0.12.x keeps working as-is.
  • The execution interface is now unified around sandbox.exec(), with session state removed so each execution is independent.
  • Transport is now RPC-only, PTY/terminal handling improved, and the code interpreter became an optional extension.
  • The self-deployed bridge isn't supported yet; the full release follows more Containers features.

This one's for developers running agent-driven workloads or sandboxed execution on Cloudflare Containers!

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