pmwarden

pmwarden is a lightweight package-manager enforcement tool for Node.js projects. It helps teams and developers ensure that a project is executed with the intended package manager, reducing inconsistencies between local development, CI pipelines, and shared environments.

Supported managers include:

• npm
• pnpm
• yarn
• bun
• cnpm

Usage

Add the following preinstall script to your project package.json

{
  // package.json
  "scripts": {
    "preinstall": "npx pmwarden pnpm"
  }
}

If the active environment resolves to a different package manager, pmwarden will fail fast and report the mismatch.

API reference

pmwarden exposes a small set of functions that can be imported directly in your own tooling or tests.

getPackageManager(userAgent?)

Parses the package manager name from an npm-style user agent string and returns it as a lowercase string.

import { getPackageManager } from 'pmwarden';

const manager = getPackageManager('pnpm/9.0.0 npm/10.8.2 node/v20.0.0 darwin arm64');
// => 'pnpm'

If no user agent is provided, it uses the current npm environment value.

isValidPackageManager(manager)

Checks whether the provided value is one of the supported package managers.

import { isValidPackageManager } from 'pmwarden';

isValidPackageManager('pnpm'); // true
isValidPackageManager('yarn'); // true
isValidPackageManager('unknown'); // false

detect(argv?, env?)

Validates the requested package manager against the detected one and prints a helpful error message when they do not match. It returns an exit status code:

• 0 when the package manager matches
• 1 when a mismatch is detected
• 2 when the input is missing or invalid

import { detect } from 'pmwarden';

const exitCode = detect(['pnpm'], process.env);

This is the function used by the CLI entry point.

License

This project is licensed under the Apache License 2.0. See the LICENSE file for details.