/sandbox-migrate-to-next

name: sandbox-migrate-to-next
description: Use when porting a Cloudflare Sandbox app from stable @cloudflare/sandbox to @cloudflare/sandbox@next (Sandbox SDK 1.0 preview), or when the user asks to migrate or upgrade to Sandbox 1.0 / @next. Not for day-to-day stable work (sandbox-stable) or new @next apps (sandbox-next).

Migrate stable → Sandbox SDK 1.0 preview (`@next`)

**Perform** the port. Follow the steps in order. Depth lives in docs—fetch the linked page when a step needs detail.

Human guide: [Migrate](https://developers.cloudflare.com/sandbox/1-0-preview/migrate/) · [1.0 preview](https://developers.cloudflare.com/sandbox/1-0-preview/)

**New projects** should start on `@next` (**`sandbox-next`**), not this skill. **Day-to-day stable work** → **`sandbox-stable`**. Deprecated-API cleanup **without** moving to `@next` → [2026 deprecation guide](https://developers.cloudflare.com/sandbox/guides/2026-deprecation/) first if needed.

Existing apps should migrate **when you can**, so you are ready when 1.0 becomes the stable release. Do **not** force production cutover without the user agreeing.

**Prefer installed `@next` types and the migrate doc over memory.**

Workflow

1. **Review** hard rules and the replacement map 2. **Audit** the codebase; list hits and target shapes 3. **Clarify** with the user (cutover, bridge, Python image, unclear sites) 4. **Upgrade** package, image, and code 5. **Validate**

Stop after any step that needs a user decision.

Hard rules

• Worker package and container image must be the **same** `@next` line.
• Production cutover uses **immediate** container rollout. Stable and `@next` control protocols are incompatible both ways; gradual rollout leaves a broken mixed window. In-flight container work can stop.
• After cutover, `await sandbox.exec(...)` means process **started**, not command **finished**.
• Argv is as-is (no implicit shell). Shell syntax needs an explicit shell binary.
• Process handles have **no stdin** → terminals for interactive input.
• Observation `timeout` / `AbortSignal` cancel the **wait only**, not the process.
• No single retry loop for every error.
• Do not invent APIs (`gitCheckout` on core, process stdin, string-exec completion helper).
• Self-deployed bridge stays on **stable** (not part of the preview line yet).

Replacement map

| Stable | `@next` | | ------ | ------- | | `SANDBOX_TRANSPORT` / `transport` / `setTransport` | Remove — RPC only | | `await sandbox.exec("cmd")` → buffered result | `await sandbox.exec(argv)` → handle, then `output` / waits | | `execStream` / `startProcess` | Same handle: `logs`, `waitFor*`, `kill` | | Default / named sessions | Gone — `cwd`/`env` per launch, or one shell script | | `sandbox.terminal(request)` / session terminal | `createTerminal` + `terminal.connect(request)` | | xterm `sessionId` | `terminalId` | | Interpreter methods on `Sandbox` | `withInterpreter` → `sandbox.interpreter.*` | | `gitCheckout` | argv `git` via `exec` | | String kill signals | Numeric only | | Files, mounts, backups, ports, tunnels, `proxyToSandbox` | Mostly unchanged (ignore session/transport bits on stable pages) |

Depth: [Migrate](https://developers.cloudflare.com/sandbox/1-0-preview/migrate/) · after port, day-to-day → **`sandbox-next`**

Audit

rg 'SANDBOX_TRANSPORT|transport:|setTransport|enableDefaultSession|createSession|getSession|deleteSession|execStream\(|startProcess\(|killProcess\(|sandbox\.terminal\(|sessionId|gitCheckout\(|SandboxTransport|ExecutionSession'

Also: string `exec(`, `cd` then a later `exec`, bare `createCodeContext` / `runCode` on `Sandbox`.

Clarify (ask when needed)

• OK to cut production with `--containers-rollout=immediate` (live processes/terminals/streams may stop)?
• Self-deployed bridge? Leave on stable.
• Python interpreter → **`-python`** image variant?
• Call sites not covered by the map?

Upgrade

Package and image

npm install @cloudflare/sandbox@next

FROM cloudflare/sandbox:next
# Python: cloudflare/sandbox:next-python

Same prerelease tag on Worker and image when not on floating `next`.

Code by area

Apply replacements from the map. For each area, implement from the doc—not from stable habits:

| Area | Doc | | ---- | --- | | Commands / handles / waits | [Processes](https://developers.cloudflare.com/sandbox/1-0-preview/processes/) · [Processes API](https://developers.cloudflare.com/sandbox/1-0-preview/api/processes/) | | `cwd` / `env` / secrets | [Environment](https://developers.cloudflare.com/sandbox/1-0-preview/environment/) · [Outbound traffic](https://developers.cloudflare.com/sandbox/guides/outbound-traffic/) | | Drop sessions | [Migrate](https://developers.cloudflare.com/sandbox/1-0-preview/migrate/) · [Lifecycle](https://developers.cloudflare.com/sandbox/1-0-preview/lifecycle/) | | Terminals | [Terminals](https://developers.cloudflare.com/sandbox/1-0-preview/terminals/) | | Interpreter | [Interpreter](https://developers.cloudflare.com/sandbox/1-0-preview/interpreter/) | | Errors | [Errors](https://developers.cloudflare.com/sandbox/1-0-preview/errors/) | | Durable job across requests | [Process execution — lifetime / durability](https://developers.cloudflare.com/sandbox/1-0-preview/processes/) |

**Commands (shape):**

// Before (stable)
const result = await sandbox.exec("npm test");

// After (@next)
const process = await sandbox.exec(["/bin/bash", "-lc", "npm test"]);
const result = await process.output({ encoding: "utf8" });

const server = await sandbox.exec(["/bin/bash", "-lc", "npm run dev"], {
  cwd: "/workspace/app",
});
await server.waitForPort(3000, { timeout: 60_000 });
await server.kill(); // numeric; default 15

**Terminals (shape):**

const terminal = await sandbox.createTerminal({ command: ["bash"], cwd: "/workspace" });
const t = await sandbox.getTerminal(terminal.id);
if (!t) return new Response("terminal gone", {