TypeScript Sandbox SDK

The TypeScript SDK exposes two clients over the same sandbox resources:

import { Inngest } from "inngest";
import { sandboxMiddleware } from "inngest/experimental";

const inngest = new Inngest({
  id: "sandbox-demo",
  middleware: [sandboxMiddleware()],
});

// Direct REST-backed client
await inngest.sandboxes.create({
  name: "direct-sandbox",
  vcpu: 2,
  memoryMb: 512,
});

// Memoized middleware-backed step client
await step.sandbox.create("step-id", {
  name: "durable-sandbox",
  vcpu: 2,
  memoryMb: 512,
});

Live streams and file bodies cannot be reconstructed from memoized JSON step state, so they are deliberately excluded from step.sandbox.

sandboxMiddleware() is required only for the durable step.sandbox surface. The direct inngest.sandboxes client works without it.

Read Sandbox limitations before relying on process recovery, output retention, stream delivery, custom runtime configuration, or idempotency.

Sandbox resource

Create, List, and Get use one resource shape:

interface SandboxResource {
  id: string;
  name: string;
  status:
    | "PENDING"
    | "STARTING"
    | "RUNNING"
    | "PAUSED"
    | "TERMINATING"
    | "TERMINATED"
    | "FAILED";
  vpcId: string;
  imageRef: string;
  resources: {
    vcpu: number;
    memoryMb: number;
  };
  createdAt: string;
  startedAt?: string;
  endedAt?: string;
  error?: string;
}

id and vpcId are canonical lowercase UUIDs. Timestamps are RFC 3339 strings.

Create currently chooses the workspace's default egress-only VPC and default image. vpcId and imageRef describe the created resource; they are not Create options.

Sandbox objects are immutable snapshots:

const sandbox = await inngest.sandboxes.get(sandboxId);

if (sandbox) {
  console.log(Object.isFrozen(sandbox));           // true
  console.log(Object.isFrozen(sandbox.resources)); // true
}

Each Get returns a new object. It never mutates an earlier snapshot.

Process resource

interface SandboxProcessResource {
  id: string;
  command: readonly string[];
  pid?: number;
  state:
    | "STARTING"
    | "RUNNING"
    | "EXITED"
    | "KILLED"
    | "FAILED"
    | "LOST";
  exitCode?: number;
  terminationSignal?: number;
  startedAt?: string;
  endedAt?: string;
}

The public process ID is a UUID, not an internal p1 or p2 guest handle. pid is visible to commands inside the sandbox. exitCode is present only for EXITED; terminationSignal is present only for KILLED.

Reconnecting by ID

Store the sandbox ID when work needs to reconnect later:

const sandboxId = sandbox.id;
const current = await inngest.sandboxes.get(sandboxId);

Inside an Inngest function, use the durable Get operation:

const current = await step.sandbox.get("get-sandbox", sandboxId);

Get returns current state and confirms that the sandbox still exists in the active workspace. Reload a process through its sandbox:

const process = await current?.processes.get(processId);

Direct client: inngest.sandboxes

The direct client:

• uses the Inngest client's base URL, signing key, environment headers, and Fetch implementation;
• requires a signing key;
• executes each call immediately;
• never retries automatically or reconnects a stream; and
• returns SandboxError for API and transport failures.

Keep it in trusted server-side code.

create(options)

const sandbox = await inngest.sandboxes.create({
  name: "agent_job-42",
  vcpu: 2,
  memoryMb: 512,
});

An active name must be unique in the workspace.

Create returns a full Sandbox:

• HTTP 201 becomes RUNNING;
• HTTP 202 becomes STARTING.

The SDK does not poll a STARTING sandbox. Call inngest.sandboxes.get() or step.sandbox.get() with a bound.

list(options?)

let cursor: string | undefined;

do {
  const result = await inngest.sandboxes.list({
    cursor,
    limit: 100,
  });

  for (const sandbox of result.items) {
    console.log(sandbox.id, sandbox.status);
  }

  cursor = result.page.cursor;
} while (cursor);

interface SandboxListResult<TSandbox> {
  items: TSandbox[];
  page: {
    cursor?: string;
    hasMore: boolean;
    limit: number;
  };
  fetchedAt: string;
}

Sandbox List orders by creation time descending, then ID descending. It includes active and retained terminal resources. Cursors are opaque.

get(sandboxId)

const sandbox = await inngest.sandboxes.get(sandboxId);

Returns a Sandbox or null when the resource is missing or hidden by workspace scope. Other errors are thrown.

sandboxId must be a canonical lowercase, non-nil UUID.

sandbox.destroy()

const result = await sandbox.destroy();

type SandboxDestroyResult =
  | {
      status: "TERMINATING";
      sandbox: SandboxRef;
    }
  | {
      status: "TERMINATED";
      sandbox: null;
    };

TERMINATING means the destroy intent was accepted and teardown continues. TERMINATED means teardown completed synchronously. A missing sandbox throws sandbox_not_found.

sandbox.commands.run(options)

const result = await sandbox.commands.run({
  command: ["/bin/sh", "-c", "printf 'tests passed\n'"],
  environment: {
    PATH: "/usr/local/bin:/usr/bin:/bin",
    CI: "true",
  },
  cwd: "/",
  timeout: "5m",
});

Numeric durations are milliseconds. Strings accept forms such as "500ms", "30s", and "5m". Temporal.Duration is also supported, except calendar years, months, and weeks.

type SandboxCommandOutputMetadata =
  | {
      truncated: false;
    }
  | {
      truncated: true;
      strategy: "tail";
      originalBytes: {
        stdout: number;
        stderr: number;
      };
      retainedBytes: {
        stdout: number;
        stderr: number;
      };
    };

interface SandboxCommandResult {
  stdout: Uint8Array;
  stderr: Uint8Array;
  exitCode: number;
  output: SandboxCommandOutputMetadata;
}

The direct client accepts up to 4 MiB across stdout and stderr and reports output: { truncated: false }. A non-zero exit code is a successful result, not an exception.

sandbox.logs.stream(options?)

const stream = await sandbox.logs.stream({ follow: true });
const reader = stream.getReader();

for (;;) {
  const { done, value } = await reader.read();
  if (done) break;

  console.log(value.stream, new TextDecoder().decode(value.data));
}

follow defaults to false.

interface SandboxOutputChunk {
  stream: "STDOUT" | "STDERR";
  data: Uint8Array;
  at?: string;
}

The SDK decodes base64 NDJSON frames. A terminal errors[] frame makes the stream throw SandboxError. Cancelling the ReadableStream aborts the HTTP request. The SDK never reconnects automatically.

sandbox.files.upload(options)

const uploaded = await sandbox.files.upload({
  path: "/tmp/input.bin",
  data: new Uint8Array([0x00, 0xff]),
  mode: 0o640,
});

Uploads are limited to 100 MiB. A successful upload atomically replaces a regular file. It cannot replace /, a directory, symlink, device, socket, or FIFO.

An upload can return operation_ambiguous after replacement may have committed. Inspect the target before deciding whether to upload again.

sandbox.files.download(options)

const response = await sandbox.files.download({
  path: "/tmp/output.bin",
});

const bytes = new Uint8Array(await response.arrayBuffer());
const mode = response.headers.get("X-Sandbox-File-Mode");
const modifiedAt = response.headers.get("Last-Modified");

Returns the raw Fetch Response. Successful responses contain Content-Type, Content-Length, X-Sandbox-File-Mode, and, when available, Last-Modified.

Only regular files up to 100 MiB are downloadable.

sandbox.processes.start(options)

const process = await sandbox.processes.start({
  command: ["/bin/sh", "-c", "while :; do sleep 1; done"],
  environment: {
    PATH: "/usr/local/bin:/usr/bin:/bin",
  },
  cwd: "/",
});

Uses the same command, environment, and working-directory rules as captured Exec, but has no runtime timeout. Returns a RUNNING process with UUID and PID.

sandbox.processes.list(options?)

const page = await sandbox.processes.list({
  cursor,
  limit: 50,
});

SandboxProcessListOptions and SandboxProcessListResult use the same cursor, limit, items, page, and fetchedAt shapes as Sandbox List.

Pages are ordered by process UUID and include terminal processes while their metadata remains. Internal guest handles are excluded.

sandbox.processes.get(processId)

const process = await sandbox.processes.get(processId);

Returns a process snapshot or null.

Process methods

const current = await sandbox.processes.get(process.id);

await process.signal({
  signal: 15,
  includeChildren: false,
});

const terminal = await process.wait({ timeout: "1m" });
const output = await process.getOutput({ tailBytes: 64 * 1024 });
const stream = await process.streamOutput({ tailBytes: 8 * 1024 });

See Managed processes for state, signal, Wait, retention, and streaming semantics.

Step client: step.sandbox

Each operation that communicates with the API adds a stable step ID as its first argument:

const sandbox = await step.sandbox.create("create-sandbox", {
  name: "agent_job-42",
  vcpu: 2,
  memoryMb: 512,
});

const page = await step.sandbox.list("list-sandboxes", { limit: 50 });
const loaded = await step.sandbox.get("get-sandbox", sandbox.id);

const result = await sandbox.commands.run("run-command", {
  command: ["/bin/true"],
});

const process = await sandbox.processes.start("start-process", {
  command: ["/bin/sh", "-c", "while :; do sleep 1; done"],
  cwd: "/",
});

const processPage = await sandbox.processes.list("list-processes", {
  limit: 50,
});
const loadedProcess = await sandbox.processes.get(
  "get-process",
  process.id,
);

await process.signal("stop-process", {
  signal: 15,
  includeChildren: false,
});

const terminal = await process.wait("wait-process", {
  timeout: "1m",
});

const output = await process.getOutput("get-output", {
  tailBytes: 64 * 1024,
});

await sandbox.destroy("destroy-sandbox");

Complete signatures:

step.sandbox.create(step, options)
step.sandbox.list(step, options?)
step.sandbox.get(step, sandboxId)

sandbox.destroy(step)
sandbox.commands.run(step, options)
sandbox.processes.start(step, options)
sandbox.processes.list(step, options?)
sandbox.processes.get(step, processId)

process.signal(step, options)
process.wait(step, options?)
process.getOutput(step, options?)

step is a string ID or { id, name? }.

Replay and retries

The opt-in Sandbox middleware wraps each call in an ordinary step.run. The handler calls inngest.sandboxes, converts the result to JSON-safe data, and returns it for memoization.

• Retriable SandboxError becomes an ordinary retriable step error.
• Non-retryable SandboxError becomes NonRetriableError.
• SandboxValidationError becomes NonRetriableError.

On replay, a completed step reconstructs the Sandbox object from its memoized result.

There is no sandbox-specific executor opcode or dispatch fence. A mutation can happen twice if REST commits and the function process stops before the result is persisted. An observed operation_ambiguous is non-retriable.

Durable captured-output limit

step.sandbox retains at most 2 MiB across stdout and stderr before returning from step.run. It reserves half for each stream, gives unused capacity to the other stream, and keeps each tail.

Larger successful commands do not throw. Inspect result.output:

if (result.output.truncated) {
  console.warn({
    strategy: result.output.strategy,
    original: result.output.originalBytes,
    retained: result.output.retainedBytes,
  });
}

Excluded methods

step.sandbox deliberately does not expose:

sandbox.logs
sandbox.files
process.streamOutput()

Use inngest.sandboxes for live streams and file bodies.

Decode binary output

All command, log, and process output is Uint8Array.

const stdout = new TextDecoder().decode(result.stdout);

For streaming UTF-8, reuse a decoder so split multi-byte characters are handled correctly. Use one decoder per stream when stdout and stderr are decoded separately.

Handle errors

Inside an Inngest function, do not catch step.sandbox errors merely to log or retry them. Let them escape. The middleware turns retryable sandbox errors into retriable step errors and non-retryable failures into NonRetriableError.

Catch a failed step only when you intend to recover with a fallback, compensate for earlier work, or deliberately mark the error as handled.

The direct inngest.sandboxes client does not receive Inngest's automatic retries. It throws SandboxError for API and transport failures and SandboxValidationError for invalid local input or malformed responses. If you catch either error outside an Inngest function, make sure your code owns the resulting retry or reconciliation policy.

Read Sandbox errors and retries before implementing retry logic.