Cellix

Native Windows agent sandbox — npm install cellix — real node.exe / npm.cmd / MSVC on the host, not WSL2.

Status: MVP preview (v0.2.0 · 2026-06-20) · config v0.2 · MXC public preview · blast-radius reducer, not a kernel security product.

The problem (Cursor, Claude, and every Windows agent)

| Product | Windows sandbox today | Pain | |---------|----------------------|------| | Cursor | Linux sandbox inside WSL2 | Agents run Linux binaries — not native node.exe, npm.cmd, or MSVC on your Windows project. | | Claude Code | No native Windows — use WSL2 | Docs: "Native Windows is not supported. On Windows, run Claude Code inside a WSL2 distribution." | | Browser/AppContainer primitives | Built for browsers | Cursor: "tailored to browsers and do not support general-purpose developer tools." | | Microsoft MXC (Build 2026) | OS-level execution containers | Raw policy JSON — no agent presets, action logs, or exec() ergonomics. |

Cellix closes that gap: Microsoft MXC processcontainer on native Windows 11, with agent-friendly createAgentSandbox() → exec() → audit JSON at .cellix/sessions/cellix-<uuid>.json.

Independent library — not a Cursor or Anthropic product. Reference only.

Who buys / builds with Cellix

| You are… | Cellix gives you… | |----------|-------------------| | Custom agent harness on Windows | Native toolchain + session logs without WSL2 translation. | | Cursor power user needing native exec | Sidecar pattern — see docs/cursor.md. | | Claude Code on Windows hitting WSL2 limits | Native node/npm on the same drive as your repo. | | MXC early adopter | Presets, mirror modes, structured Action logs on top of @microsoft/mxc-sdk. |

When to use what

| Approach | Best for | |----------|----------| | Cellix | Native Windows dev tools, same node_modules layout, MSVC, real PATH. | | WSL2 sandbox (Cursor / Claude default) | Linux-only toolchains, acceptable VM hop. | | Docker | Reproducible Linux images; extra VM boundary on Windows. | | No sandbox | Maximum risk — approval fatigue or full trust. |

Quick start

npm install cellix
cp .env.example .env   # set CELLIX_WORKSPACE

import { loadCellixEnvFile, readCellixConfig, mergeSandboxOptions, createAgentSandbox, getSupportStatus } from 'cellix';

loadCellixEnvFile();
if (!getSupportStatus().supported) throw new Error('unsupported host');

const box = createAgentSandbox(
  mergeSandboxOptions({ preset: 'node-dev' }, readCellixConfig()),
);
console.log((await box.exec('node -e "console.log(2)"')).stdout);
await box.destroy();

Configuration (v0.2)

| Variable | Default | One line | |----------|---------|----------| | CELLIX_MIRROR | minimal | PATH mirror: minimal, full, or none | | CELLIX_WORKSPACE | — | Agent readwrite project root | | CELLIX_TIMEOUT | 300000 | Per-exec timeout (ms) | | CELLIX_LOGS | .cellix/sessions | Session JSON directory | | CELLIX_DEBUG | 0 | 1 = [cellix:exec] phase logs |

See docs/config.md — legacy CELLIX_*_PATH aliases still supported.

Prerequisites

| Requirement | One line | |-------------|----------| | OS | Windows 11 24H2+ (build 26100) | | Node | ≥ 18 (ESM only) | | MXC | Bundled @microsoft/[email protected] | | Preflight | npm run diagnose or getSupportStatus() |

Commands

| Command | One line | |---------|----------| | npm run ci | Build + unit tests | | npm test | 55 unit tests | | npm run example:cursor | Native Windows pattern vs Cursor WSL2 gap | | npm run diagnose | MXC preflight | | npm run benchmark | Cellix vs Docker on Windows |

Documentation

| Doc | One line | |-----|----------| | docs/positioning.md | Cursor / Claude / MXC comparison (sales) | | docs/cursor.md | Sidecar pattern for Cursor workspaces | | docs/config.md | Config v0.2 design | | docs/scaling.md | Multi-agent + CI/CD | | CHANGELOG.md | Release history |

License

MIT — LICENSE.md · Security — SECURITY.md