coden-msb

A CodeN npm plugin that runs Python inside a disposable MicroSandbox microVM. Unlike running Python directly in the agent's /tmp, each call boots a fresh, hardware-isolated container, executes the script, returns its output, and then destroys the container.

Tools

| Tool | Purpose | Risk | | ---- | ------- | ---- | | msb_python | Run a Python script in a disposable microVM and return output | modify |

msb_python accepts code (required) and optional image (default python:3.12-slim), cpus (1), memory (512 MiB), timeout (60s), and network (false). Network is off by default; set network: true to allow sandbox egress.

Requirements

• MicroSandbox runtime (installed automatically by the microsandbox npm dependency on first use; needs a KVM/hypervisor-capable host, e.g. Apple Silicon on macOS).
• CodeN ≥ 0.1.0 with npm plugin support.

Install into CodeN

coden plugin install npm:coden-msb
coden plugin list

Install locally for a single project, or --global for the current user. Installing or upgrading requires a CodeN restart. The microsandbox dependency (and its platform binary) is installed into the plugin runtime automatically — you don't install microsandbox separately.

Development

bun install
bun run check     # biome + tsc + vitest (offline)
CODEN_LIVE_TEST=1 vitest run test/live.test.ts   # real microVM smoke
bun run build     # bundle src/ -> dist/index.js

Publishing / Release

.github/workflows/publish.yml publishes to npm when you push a v* tag (or run it manually via Actions → Publish to npm → Run workflow). It requires a GitHub secret named NPM_TOKEN set to an npm auth token with publish access for the coden-msb package.

Create a version tag matching package.json and push it:

# bump version in package.json first, then:
git tag v0.1.0
git push origin v0.1.0

The workflow verifies the tag matches package.json, runs bun run check, then npm publish (which runs prepack → build and prepublishOnly → check). Configuring this release action the first time:

1. Generate an npm token (npm token create) with publish scope.
2. Add it as a GitHub repo secret named NPM_TOKEN (Settings → Secrets and variables → Actions).

Not a sandbox substitute

The plugin runs in the CodeN process and owns host permissions. MicroSandbox isolates the Python execution, but CodeN plugins are not a security sandbox. The network: false default reduces egress; resource limits prevent runaway.