Sandbox Migrate to Next skill for Claude Code: port a Sandbox app to 1.0 preview

Cloudflare's skill that makes Claude port a Sandbox app from the stable SDK to @next, for teams moving to the 1.0 preview.

Installs: 73.1K; on skills.sh
Stars: 3.2K; on GitHub
Files: 1; besides SKILL.md
Updated: Oct 2026; last repo commit

Claude works through five steps in order: review the hard rules and replacement map, audit your code for stable-only APIs, ask you the open questions, upgrade the package, image and code, then validate. It stops after any step that needs a decision from you.

The upgrade step runs npm install for the preview package and edits your Dockerfile. The production deploy uses an immediate container rollout, which can stop work that is running. The SKILL.md says not to force a production cutover without your agreement. It bundles one reference file and no scripts.

Good for

Teams with a stable Cloudflare Sandbox app that want to move to 1.0 preview
Developers who need a checklist for the exec, session and terminal API changes
Reviewers planning a safe production cutover

Install sandbox-migrate-to-next

Claude Code

Copy this prompt.

Install the sandbox-migrate-to-next skill in Claude Code. Run this command:

/plugin marketplace add cloudflare/skills
/plugin install cloudflare@cloudflare

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

The three Sandbox skills hand over to each other: each one stops and loads another when it finds the wrong package line, so install all three. The plugin installs every Cloudflare skill plus Cloudflare's main remote MCP server (README). Pick one route, not both. Start a new session afterwards.

From the project README. Source.

What's in the skill

When it loads

Migrate Cloudflare Sandbox apps from stable @cloudflare/sandbox to @cloudflare/sandbox@next (SDK 1.0 preview). Use sandbox-next for apps already on the preview.

Sections in SKILL.md

Workflow
Hard rules
Replacement map
Audit
Clarify (ask when needed)
Upgrade
Package and image
Code by area
Deploy cutover
Validate
Red flags — stop and fix
Skill feedback

Key facts

Author: Cloudflare
Repository: cloudflare/skills
Installs on skills.sh: 73,079 (2 Nov 2026)
GitHub stars (repo): 3,244 (2 Nov 2026)
License: Apache-2.0
Last commit (repo): 31 Oct 2026
What installs: SKILL.md and references/skill-feedback.md (2 files); bundles no scripts
Works in: Claude Code, Codex, Cursor and VS Code / GitHub Copilot (install routes listed in the README)
skills.sh audits: Gen Agent Trust Hub pass, Socket pass, Snyk warn

What it includes

Read the hard rules and the replacement map
Claude learns the rules: package and image on the same @next line, exec returns when the process starts, no implicit shell, no stdin on handles.
Read · 1. Review
Search your code for stable-only APIs
Claude runs the skill's search command for transport settings, sessions, execStream, startProcess, terminal and gitCheckout, and lists what it finds.
Runs code · 2. Audit
Ask you about cutover, bridge, Python image and unclear sites
Claude asks before it changes anything that needs a decision, such as production cutover and Python interpreter images.
Read · 3. Clarify
Change the package, image and code
Claude installs the preview package, switches the Dockerfile base image, and rewrites calls from string exec to argv exec with handles, sessions to cwd and env, and terminals to createTerminal.
Try: “Migrate this Worker from @cloudflare/sandbox to @next and list every change.”
Runs code · 4. Upgrade
Typecheck, smoke tests and a second search for removed APIs
Claude checks lockfile and Dockerfile, typechecks, runs small smoke tests and searches again for removed APIs.
Runs code · 5. Validate
Immediate container rollout for production
The skill gives a wrangler deploy command with an immediate containers rollout. After it runs, old process and terminal IDs stop working.
Runs code · Deploy cutover
Draft a public GitHub issue about the skill, only with your approval
If you say the skill gave wrong or outdated advice, Claude can draft an issue for you to review before anything is posted.
Network · Skill feedback

From the official docs

Permissions

Medium risk

This skill rewrites your app and ends with a production deploy that can interrupt work that is already running. Work on a branch, try staging first, and approve the production deploy yourself.

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

Production cutover can stop running container work
The SKILL.md says production uses an immediate container rollout and in-flight processes, terminals and streams can stop. Deploy to staging first and only cut over when you agree.
It rewrites your dependencies, image and code
Claude changes the package, Dockerfile base image and many call sites. Work on a branch and read the diff.
Feedback can open a public GitHub issue
The skill's feedback steps ask permission, show you the exact title and body, and post to cloudflare/skills only after you say yes. Keep secrets, account IDs and private code out of that text. github.com

Security advisories

No published security advisories as of Nov 2, 2026.

Technical details

Turning on read-only	The skill defines no read-only switch.
Talks to	npm registry. Cloudflare, when you deploy. GitHub, only if you approve a feedback issue
Scopes	Claude edits package.json, lockfile, Dockerfile and Sandbox code Claude runs npm install for @cloudflare/sandbox@next and a code search The production step is a wrangler deploy command

Questions

What does the Sandbox Migrate to Next skill do?

It makes Claude port a Cloudflare Sandbox app from the stable @cloudflare/sandbox package to the @next preview. It follows five steps and stops whenever a decision is yours.

Should I migrate now?

The SKILL.md says existing apps should migrate when you can, so you are ready when 1.0 becomes the stable release. It also says not to force a production cutover without your agreement. New projects should start on @next with sandbox-next instead.

Can the migration break production?

It can if you cut over carelessly. The skill says production cutover uses an immediate container rollout, that stable and @next control protocols are incompatible both ways, and that in-flight container work can stop. Try staging or a branch first.

How do I install it?

Use the install box at the top of this page. The README also documents a Claude Code plugin (/plugin marketplace add cloudflare/skills, then /plugin install cloudflare@cloudflare) that installs all of Cloudflare's skills together with Cloudflare's main MCP server. Start a new session afterwards.

Sandbox Migrate to Next vs sandbox-next?

Use this skill once, to port a stable app. After the port, day-to-day work uses sandbox-next. Apps that stay on the stable package use sandbox-stable.

Is it safe to install?

Use it with care. It changes your dependencies and Dockerfile and gives a production deploy command, so review every change and deploy to staging first. Claude can also open a public GitHub issue about the skill, but only after you approve the exact text.

Information

updated Nov 2, 2026

Repository: cloudflare/skills
Folder: skills/sandbox-migrate-to-next

cloudflare/skills skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 4

cloudflare/skills README · github.com
skills CLI commands · github.com
sandbox-migrate-to-next SKILL.md · github.com
sandbox-migrate-to-next skill-feedback.md · github.com