@mammothb/pi-eval

A pi extension that adds an eval tool for executing JavaScript and Python code in isolated subprocesses

Packages

Package details

extension

Install @mammothb/pi-eval from npm and Pi will load the resources declared by the package manifest.

npm report

$ pi install npm:@mammothb/pi-eval

Package: @mammothb/pi-eval
Version: 2.1.1
Published: Jun 13, 2026
Downloads: 1,117/mo · 1,117/wk
Author: mammothb
License: MIT
Types: extension
Size: 24.5 KB
Dependencies: 1 dependency · 4 peers

Pi manifest JSON

{
  "extensions": [
    "./index.ts"
  ]
}

Security note

Pi packages can execute code and influence agent behavior. Review the source before installing third-party packages.

README

pi-eval

A pi extension that adds an eval tool for executing JavaScript and Python code in isolated subprocesses.

Usage

Once installed, the LLM can call the eval tool to run code snippets without managing temp files. Each call spawns a fresh subprocess — no state persists between calls.

Tool parameters

Parameter	Type	Default	Description
`language`	string	(required)	Programming language: `"javascript"` or `"python"`
`code`	string	(required)	Code to execute
`cwd`	string	agent's cwd	Working directory for the subprocess

Runtime configuration

Python binary and Node.js module paths are configured via JSON files, not per-call parameters:

Global: ~/.pi/agent/pi-eval.json
Project: .pi/pi-eval.json (overrides global)

{
  "pythonPath": ".venv/bin/python3",
  "nodeModulesPath": "./node_modules"
}

Relative paths in project configs are resolved relative to the project root.

Features

JavaScript: Writes code to a temp file, spawns node as a subprocess. Console output is captured as labeled STDOUT: / STDERR: sections. Set nodeModulesPath in config to make project packages available via require().
Python: Spawns python3 with -c, capturing stdout/stderr identically. By default, searches PATH for python3 (falling back to /usr/bin/python3, /usr/local/bin/python3). Set pythonPath in config to target a venv or custom binary.
Safety: 30-second timeout, 1 MB output cap, Escape to cancel a running evaluation.