@microsoft/mxc-sdk

Node.js / TypeScript SDK for MXC (Microsoft eXecution Containers). The versioned public request, execution, and lifecycle APIs are exported from @microsoft/mxc-sdk/v1, including platform discovery, errors, and telemetry consent. The package root exports no public APIs. These APIs use the SDK-owned V1 contract; callers do not select the wire version.

npm install @microsoft/mxc-sdk

Node.js 24 or later is required. On Windows, native stdio transfer requires Node.js 24.21.0 or later within the Node.js 24 release line, or Node.js 26.8.0 or later.

Run to completion

import { getPlatformSupport } from '@microsoft/mxc-sdk/v1';
import { run } from '@microsoft/mxc-sdk/v1';
import type { ContainerRequest } from '@microsoft/mxc-sdk/v1';

if (!getPlatformSupport().isSupported) {
  throw new Error('MXC is not available on this host');
}

const request: ContainerRequest = {
  filesystem: { readonlyPaths: [process.cwd()] },
  network: { egress: { default: 'deny' } },
  timeoutMs: 30_000,
  command: 'node -e "console.log(\'hello from container\')"',
};

const output = await run(request);
console.log(output.stdout, output.exitCode);

run returns a Promise<ExecutionResult> containing captured stdout, stderr, the workload exit code, timeout state, warnings, and optional output metadata.

Spawn with streaming output

import { spawn } from '@microsoft/mxc-sdk/v1';

const processHandle = await spawn({
  command: 'node -e "console.log(\'hello from container\')"',
  timeoutMs: 30_000,
});
try {
  processHandle.standardOutput?.on('data', (chunk) => process.stdout.write(chunk));
  processHandle.standardError?.on('data', (chunk) => process.stderr.write(chunk));
  console.log(await processHandle.wait());
} finally {
  processHandle.dispose();
}

spawn returns a Promise<MxcProcess> with standard pipes, wait, termination, and disposal operations. Access output streams before awaiting completion; any untaken streams are drained internally to avoid pipe-buffer deadlocks. Each operation accepts its own optional options type: RunOptions, SpawnOptions, or SpawnWithPtyOptions. Execution options do not support dryRun.

ContainerRequest holds the command, cross-backend filesystem, network, and UI settings, and the selected backend's typed configuration. The SDK selects its exact V1 contract; callers do not provide a schema version or raw executor configuration.

When UI settings are supplied, ui.disable explicitly controls whether UI is disabled; clipboard and input-injection permissions remain separate.

Spawn with a caller-controlled terminal

PTY execution supports all backends except WSLc.

import { spawnWithPty } from '@microsoft/mxc-sdk/v1';

const terminal = await spawnWithPty({
  containment: { type: 'isolation_session' },
  command: 'cmd.exe',
  network: {
    egress: { default: 'allow' },
    ingress: { default: 'allow', hostLoopback: 'allow' },
  },
  timeoutMs: 30_000,
}, { size: { rows: 24, columns: 80 } });
try {
  terminal.output.on('data', (chunk) => process.stdout.write(chunk));
  terminal.input.end('echo hello from terminal\r\nexit\r\n');
  console.log(await terminal.wait());
} finally {
  terminal.dispose();
}

spawnWithPty returns a Promise<MxcPtyProcess> with merged terminal output and resizing support. Initial dimensions default to 24 rows by 80 columns. Terminal stderr is merged into output. Closing input requests terminal EOF when supported; raw-mode applications must use their own completion protocol. Seatbelt rejects PTY mode with guiAccess or legacy launchMethod: "open". Unsupported combinations are rejected before sandbox creation.

Lifecycle API

ProvisionResult<C>.metadata uses ProvisionMetadata<C> to select the backend's metadata type. IsolationSession returns IsolationSessionProvisionMetadata; WSLC returns no provision metadata.

The V1 lifecycle API provisions and controls supported persistent backends. provisionContainer returns a branded ContainerId; use it for later phases without inspecting its runtime string.

import {
  deprovisionContainer,
  runInContainer,
  provisionContainer,
  startContainer,
  stopContainer,
} from '@microsoft/mxc-sdk/v1';

const { containerId } = await provisionContainer({
  containment: 'isolation_session',
  network: {
    egress: { default: 'allow' },
    ingress: { default: 'allow', hostLoopback: 'allow' },
  },
});
try {
  await startContainer(containerId);
  try {
    const result = await runInContainer(containerId, {
      command: 'echo hello from lifecycle',
      timeoutMs: 30_000,
    });
    console.log(result.stdout, result.exitCode);
  } finally {
    await stopContainer(containerId);
  }
} finally {
  await deprovisionContainer(containerId);
}

spawnInContainer returns a Promise<MxcProcess> with live standard pipes; runInContainer returns a Promise<ExecutionResult> with captured output. spawnInContainerWithPty(containerId, request, options?) starts an IsolationSession exec with a caller-driven terminal and returns a Promise<MxcPtyProcess>. Set options.size for initial dimensions; it defaults to 24 rows by 80 columns. IsolationSession provision requires an explicit unrestricted directional network posture; WSLC network posture is fixed at provision. See the IsolationSession and WSLC guides for backend and phase requirements.

Provisioning takes a discriminated ProvisionRequest and optional ProvisionOptions. Start, stop, and deprovision take the identity followed by their own StartOptions, StopOptions, or DeprovisionOptions. Existing-container execution takes the identity, a flat ExecutionRequest, and SpawnInContainerOptions or RunInContainerOptions; PTY execution carries initial dimensions on SpawnInContainerWithPtyOptions. Process settings use command, workingDirectory, environment, inheritDefaultEnvironment, and timeoutMs, just as creation does.

Lifecycle and existing-container options can override request telemetry. validateProvision, validateStart, validateStop, validateDeprovision, and validateProcess perform native dry-run validation without creating a container or returning an execution result. They return ValidationResult with a warnings array and use the corresponding operation options. Existing-container execution accepts runtime-only network settings at network.runtimeConfig; it cannot change the container's provision-time network policy. The runtime values are typed as NetworkRuntimeConfig.

The creation containment types are compile-time-only choices under the Containment namespace, such as Containment.Process and Containment.ProcessContainer. Containment is also their closed union; the SDK does not create runtime containment objects or factories.

ContainerRequest uses the named FilesystemPolicy, NetworkPolicy, and UiPolicy types for cross-backend restrictions. Backend-specific settings remain on the selected containment configuration.

Public V1 types

| Purpose | TypeScript type | | --- | --- | | Creation request and cross-backend restrictions | ContainerRequest | | Persistent container identity | ContainerId | | Persistent container provision input | ProvisionRequest | | Existing-container workload | ExecutionRequest | | Live process with standard pipes | MxcProcess | | Live process with a terminal | MxcPtyProcess | | Terminal dimensions | MxcPtySize | | Captured execution | ExecutionResult | | Terminal process outcome | WaitResult | | Validation warnings | ValidationResult | | Provisioned identity, optional metadata, and warnings | ProvisionResult<C> | | Start, stop, and deprovision warnings | LifecycleResult | | Structured execution outputs | ExecutionMetadata | | Denial-capture output and failure | CaptureDenialsResult, CaptureDenialsError | | Runtime network values | NetworkRuntimeConfig | | Native host backend and optional capability | AvailableBackend, BackendCapability | | Consent status and operation result | TelemetryConsentStatus, TelemetryConsentOutcome | | Host consent presenter | TelemetryConsentPresenter |

Network policy details are in the networking guide; host-specific behavior and supported capabilities are documented in the backend guides under docs/. See the SDK API reference for complete signatures and types.

Errors, warnings, and telemetry

Native errors are surfaced as MxcError with a typed error code and optional operation, native status, and remediation. Security and operational warnings are returned in ExecutionResult.warnings and MxcProcess.warnings. Captured stdout and stderr are workload output; warnings and structured denial-capture metadata are not appended to those streams. Validation warnings are returned in ValidationResult.warnings. Provision warnings are returned in ProvisionResult.warnings; start, stop, and deprovision return LifecycleResult.warnings. Omitted native warnings become an empty array; malformed warnings fail explicitly. When provision metadata is present for IsolationSession, all three fields are required: agentUserName, agentUserSid, and ephemeralWorkspacePath. ExecutionResult.outputMetadata, MxcProcess.outputMetadata, and the inherited PTY property expose optional ExecutionMetadata. Live-process metadata is available after terminal settling; denial-capture fields are populated only when the backend produces them.

Creation telemetry is supplied through telemetry: { enabled: true } on RunOptions, SpawnOptions, or SpawnWithPtyOptions, not on ContainerRequest. Omission leaves telemetry disabled; enabled: false explicitly disables it. Opt-in remains subject to MXC's persisted user consent and administrative policy. Telemetry consent APIs and getPlatformSupport are exported from @microsoft/mxc-sdk/v1.

getTelemetryConsentStatus reads stored/effective consent and policy, requestTelemetryConsent accepts an application-owned presenter, and withdrawTelemetryConsent withdraws consent. Each returns a Promise. These operations are Windows-only and report not-applicable on other platforms.

getAvailableBackends() reads native host availability, isolation tiers, capabilities, and warnings through in-process mxc_ffi. It returns AvailableBackend[]; a reported host backend is not necessarily launchable through V1 creation. Discovery is advisory, and launch-time validation still applies. Native failures and malformed discovery results throw rather than reporting an unsupported host.

Filesystem discovery helpers and their result/options types are grouped under policy.filesystem from @microsoft/mxc-sdk/v1. They take an optional environment map; omission uses process.env, and {} stays empty. getAvailableToolsPolicy also accepts ToolsPolicyOptions; set containerType: 'processcontainer' to exclude directories with ALL APPLICATION PACKAGES access on Windows. ACL inspection is bounded to five seconds per directory; failures retain the directory and emit a diagnostic warning. getUserProfilePolicy uses the supplied environment, and getTemporaryFilesPolicy returns existing temporary storage without creating directories.