Stdio

The TypeScript SDK exposes stdio through sandbox.stdio. Use stdio.start() to launch a process with an open stdin pipe, then send data, receive output, and close stdin or kill the process. For conceptual background see the Stdio feature overview.

`sandbox.stdio.start(cmd, opts?)` → `Promise<StdioProcess>`

Start a subprocess with an open stdin pipe.

const proc = await sandbox.stdio.start("cat", {
  envs: { FOO: "bar" },
  user: "user",
  cwd: "/workspace",
  onStdout: (data) => console.log(data),
  onStderr: (data) => console.error(data),
  requestTimeout: 5000,
});

`StdioStartOpts`

Field	Type	Default	Description
`envs`	`Record<string, string>`	`undefined`	Environment variables merged into the process env.
`user`	`string`	`"user"`	User the process runs as.
`cwd`	`string`	`undefined`	Working directory.
`onStdout`	`(data: Uint8Array) => void`	`undefined`	If provided, the handle auto-opens the SSE stream and invokes this for each stdout chunk.
`onStderr`	`(data: Uint8Array) => void`	`undefined`	Same, for stderr.
`requestTimeout`	`number`	`undefined`	Per-request timeout in milliseconds for the start POST.

`StdioProcess`

Handle for an interactive subprocess with stdin pipe.

Properties

proc.cmdId: string — server-assigned command identifier.
proc.exitCode: number | null — null while the process is running.

Methods

`proc.sendStdin(data, requestTimeout?): Promise<void>`

Send data to the process’s stdin. Accepts string or Uint8Array.

await proc.sendStdin("hello\n");
await proc.sendStdin(new Uint8Array([0x04]));  // Ctrl-D

`proc.closeStdin(requestTimeout?): Promise<void>`

Close the process’s stdin pipe, sending EOF.

`proc.kill(requestTimeout?): Promise<boolean>`

Terminate the process. Returns true if the process existed at the time of the call.

`proc.wait(): Promise<StdioResult>`

Resolves when the process exits. If callbacks were provided at start time, this awaits the background stream. Otherwise it opens a new stream and drains it (discarding output).

const result = await proc.wait();
console.log(result.exitCode);

`proc.stream(opts?): Promise<StdioResult>`

Opens the SSE output stream and delivers chunks via callbacks. Resolves when the process exits.

const proc = await sandbox.stdio.start("sh -c 'echo hi; echo err >&2'");
const result = await proc.stream({
  onStdout: (d) => console.log("out:", new TextDecoder().decode(d)),
  onStderr: (d) => console.log("err:", new TextDecoder().decode(d)),
});

Use stream() when you didn’t provide callbacks at start time.

`StdioResult`

interface StdioResult {
  exitCode: number;  // -1 if the stream ended without a clean exit frame
}

Python SDK

TypeScript SDK

Go SDK

`sandbox.stdio.start(cmd, opts?)` → `Promise<StdioProcess>`

`StdioStartOpts`

`StdioProcess`

Properties

Methods

`proc.sendStdin(data, requestTimeout?): Promise<void>`

`proc.closeStdin(requestTimeout?): Promise<void>`

`proc.kill(requestTimeout?): Promise<boolean>`

`proc.wait(): Promise<StdioResult>`

`proc.stream(opts?): Promise<StdioResult>`

`StdioResult`

​sandbox.stdio.start(cmd, opts?) → Promise<StdioProcess>

​StdioStartOpts

​StdioProcess

​Properties

​Methods

​proc.sendStdin(data, requestTimeout?): Promise<void>

​proc.closeStdin(requestTimeout?): Promise<void>

​proc.kill(requestTimeout?): Promise<boolean>

​proc.wait(): Promise<StdioResult>

​proc.stream(opts?): Promise<StdioResult>

​StdioResult

`sandbox.stdio.start(cmd, opts?)` → `Promise<StdioProcess>`

`StdioStartOpts`

`StdioProcess`

Properties

Methods

`proc.sendStdin(data, requestTimeout?): Promise<void>`

`proc.closeStdin(requestTimeout?): Promise<void>`

`proc.kill(requestTimeout?): Promise<boolean>`

`proc.wait(): Promise<StdioResult>`

`proc.stream(opts?): Promise<StdioResult>`

`StdioResult`