Lelantos SDK

Firecracker microVM code sandboxes + stealth browser sandboxes for AI agents — one TypeScript SDK.

Spin up an isolated Linux microVM, run real commands with real exit codes, read and write its filesystem, and get a public preview URL — or drive a fingerprint-resistant headless browser over CDP and a no-Playwright action API. One client, one auth config, the full Lelantos platform.

Install

npm i @lelantos-ai/sdk

Short alias: npm i lelantos (re-exports this package; import … from 'lelantos').

# the browser namespace's Playwright path also needs Playwright (optional peer):
npm i playwright

Quickstart (30 seconds)

import { createLelantos } from '@lelantos-ai/sdk';

const lel = createLelantos({
  apiKey: process.env.LELANTOS_API_KEY, // lel_… or its e2b_… alias
  domain: 'lelantos.ai',
});

const sbx = await lel.compute.create('base');         // boot a microVM
const r = await sbx.runCommand('echo hello from the vm');
console.log(r.exitCode, r.stdout);                    // 0  "hello from the vm\n"

await sbx.destroy();

runCommand returns the real exit code — a genuine non-zero (including a shell 127) is surfaced immediately, never a silent fake; only transient envd cold-starts are retried with bounded backoff.

Browser sandboxes

Stealth headless Chromium/Firefox, driven with Playwright over CDP:

const { browser, artifacts, close } = await lel.browser.createBrowser({
  engine: 'chromium',                 // or 'firefox'
});
try {
  const page = await browser.newPage();
  await page.goto('https://example.com');
  await artifacts.screenshot();       // captured via CDP, persisted server-side
  await artifacts.pdf();              // chromium only
} finally {
  await close();                      // closes browser + bridge + deletes the sandbox
}

…or drive the browser without Playwright via the NDJSON /rpc action API:

const client = await lel.browser.rpc(sandboxId);

await client.navigate('https://example.com');
const snap  = await client.snapshot();                 // accessibility tree → { tree_yaml, … }
const title = await client.evaluate('document.title'); // → { value, … }

await client.send('page.scroll', { dy: 600 });         // any daemon action via send()
await client.close();

Filesystem & preview URLs

await sbx.filesystem.write('/tmp/app.py', 'print("hi")');
const files = await sbx.filesystem.list('/tmp');
const url   = await sbx.getUrl(3000);                  // https://3000-<id>.lelantos.ai

Two API styles

The package ships both surfaces — pick one, they coexist:

• Modern (recommended) — createLelantos(config) returns namespaces (compute / browser / durable / snapshot / template). Auth + domain are baked into every call; no per-call threading.
• Legacy compat — the original LelantosClient / SandboxHandle classes are still exported unchanged, so existing code keeps working. New code should prefer createLelantos.

import { LelantosClient } from '@lelantos-ai/sdk'; // legacy, still supported

Features

• Compute — E2B-compatible Firecracker microVMs: create / connect / list / destroy, runCommand with real exit codes, normalized filesystem, preview URLs.
• Browser — CDP browser sandboxes via Playwright/Puppeteer, plus a Playwright-free NDJSON /rpc action client; per-context BYO proxy (hot-swap, no restart); screenshot/PDF artifacts.
• Durable pause / resume — snapshot a compute sandbox to S3 so a pause survives a node restart (compute only).
• Snapshots & templates — create snapshots; build custom templates via the v3 pipeline.
• Dual-key auth — accepts a lel_… key or its e2b_… alias; env fallbacks for key/domain/apiUrl.
• First-class TypeScript — full types, namespaced, no codegen step.
• Escape hatches — lel.http for any endpoint not yet surfaced; sbx.getInstance() for the raw underlying handle.

Durable pause / resume (compute only)

await lel.durable.pause(sbx.id, { durable: true });    // 202, async snapshot to S3
let s = await lel.durable.get(sbx.id);                 // poll until 'durable_paused'
await lel.durable.resume(sbx.id, { timeout: 3600 });

Default pause is an in-RAM vCPU freeze (lost on node restart); durable: true survives a restart. Never use this for browser sandboxes — their state is time-sensitive.

Links

• Website — https://lelantos.ai
• Docs — https://lelantos.ai/docs
• Agent homepage (llms.txt) — https://lelantos.ai/llms.txt

License

Apache-2.0