pnpm/AGENTS.md

Agent Guide to pnpm Repository

This document provides context and instructions for AI agents working on the pnpm codebase.

Repository Structure

The pnpm codebase is a monorepo managed by pnpm itself. The root contains functional directories organized by domain:

Core Directories

• pnpm/: The CLI entry point and main package.
• pkg-manager/: Core package management logic (installation, linking, etc.).
• resolving/: Dependency resolution logic (resolvers for npm, tarballs, git, etc.).
• fetching/: Package fetching logic.
• store/: Store management logic (content-addressable storage).
• lockfile/: Lockfile handling, parsing, and utilities.

CLI & Configuration

• cli/: CLI command implementations and infrastructure.
• config/: Configuration management and parsing.
• hooks/: pnpm hooks (readPackage, etc.).
• completion/: Shell completion support.

Other Functional Directories

• network/: Network-related utilities (proxy, fetch, auth).
• workspace/: Workspace-related utilities.
• exec/: Execution-related commands (run, exec, dlx).
• env/: Node.js environment management.
• cache/: Cache-related commands and utilities.
• patching/: Package patching functionality.
• reviewing/: License and dependency review tools.
• releasing/: Release and publishing utilities.

Shared Utilities

• packages/: Shared utility packages (constants, error handling, logger, types, etc.).
• fs/: Filesystem utilities.
• crypto/: Cryptographic utilities.
• text/: Text processing utilities.

Setup & Build

To set up the environment and build the project:

pnpm install
pnpm run compile

Testing

Never run all tests in the repository as it takes a lot of time.

Run tests for a specific project instead:

# From the project directory
pnpm test

# From the root, filtering by package name
pnpm --filter <package_name> test

Or better yet, run tests for a specific file:

pnpm --filter <package_name> test <file_path>

Or a specific test case in a specific file:

pnpm --filter <package_name> test <file_path> -t <test_name_pattern>

Linting

To run all linting checks:

pnpm run lint

Contribution Workflow

Changesets

If your changes affect published packages, you MUST create a changeset file in the .changeset directory. The changeset file should describe the change and specify the packages that are affected with the pending version bump types: patch, minor, or major.

IMPORTANT: Always explicitly include "pnpm" in the changeset with the appropriate version bump (patch, minor, or major). The pnpm CLI will only receive automatic patch bumps from its dependencies, so if your change warrants a minor or major version bump for the CLI, you must specify it explicitly. The changeset description will appear on the release notes page.

Example:

---
"@pnpm/core": minor
"pnpm": minor
---

Added a new setting `blockExoticSubdeps` that prevents the resolution of exotic protocols in transitive dependencies [#10352](https://github.com/pnpm/pnpm/issues/10352).

Versioning Guidelines for pnpm CLI:

• patch: Bug fixes, internal refactors, and changes that don't require documentation updates
• minor: New features, settings, or commands that should be documented (anything users should know about)
• major: Breaking changes

Commit Messages

Follow the Conventional Commits specification. - feat: a new feature - fix: a bug fix - docs: documentation only changes - style: formatting, missing semi-colons, etc. - refactor: code change that neither fixes a bug nor adds a feature - perf: a code change that improves performance - test: adding missing tests - chore: changes to build process or auxiliary tools

Code Style

This repository uses Standard Style with a few modifications:

• Trailing commas are used.
• Functions are preferred over classes.
• Functions are declared after they are used (hoisting is relied upon).
• Import Order:
  1. Standard libraries (e.g., fs, path).
  2. External dependencies (sorted alphabetically).
  3. Relative imports.

To ensure your code adheres to the style guide, run:

pnpm run lint

Common Gotchas

Error Type Checking in Jest

When checking if a caught error is an Error object, do not use instanceof Error. Jest runs tests in a VM context where instanceof checks can fail across realms.

Instead, use util.types.isNativeError():

import util from 'util'

try {
  // ... some operation
} catch (err: unknown) {
  // ❌ Wrong - may fail in Jest
  if (err instanceof Error && 'code' in err && err.code === 'ENOENT') {
    return null
  }
  
  // ✅ Correct - works across realms
  if (util.types.isNativeError(err) && 'code' in err && err.code === 'ENOENT') {
    return null
  }
  throw err
}

Key Configuration Files

• pnpm-workspace.yaml: Defines the workspace structure.
• package.json (root): Root scripts and devDependencies.
• CONTRIBUTING.md: Detailed contribution guidelines.