o-

o- is a Rust-based JavaScript runtime with multiple engine backends and an experimental npm-style package manager.

What It Does

• runs JavaScript through SpiderMonkey, V8, or JavaScriptCore
• loads a shared jstd bootstrap layer for common host behavior
• installs npm packages into local node_modules
• supports global package installs with generated .bin shims
• writes npm-style package-lock.json files
• formats runtime and package-manager failures through a shared Report flow

Workspace Layout

• o-: CLI and top-level integration crate
• o-core: shared runtime traits and error types
• jstd: shared JavaScript bootstrap layer
• o-toolchain-javascriptcore: JavaScriptCore embedding
• o-toolchain-spidermonkey: SpiderMonkey embedding
• o-toolchain-v8: V8 embedding
• www: documentation site

Configuration

The CLI reads the default engine from:

# ~/.config/o-/config.toml
[toolchain]
name = "spidermonkey"

Built-in engine names:

• spidermonkey
• v8
• javascriptcore or jsc on macOS

CLI

o- run <path>
o- install
o- install --global <package>
o- uninstall <package>
o- toolchain add <user> <repo>
o- toolchain remove <toolchain>

Running a Script

cargo run -- run index.js

Package Manager

Local install

Inside a project with a package.json:

o- install

This installs into:

<project>/node_modules
<project>/package-lock.json

Global install

o- install --global vite
o- install --global eslint@^9

Global packages are stored in:

~/.config/o-/packages/node_modules
~/.config/o-/packages/package-lock.json

Generated shims are stored in:

~/.config/o-/packages/node_modules/.bin

Uninstall

o- uninstall vite

Uninstall removes:

• the installed package directory
• generated .bin shims
• the matching entry in the global lockfile

Current Package-Manager Scope

Implemented:

• dependencies
• devDependencies
• optionalDependencies
• peerDependencies
• tarball download and extraction
• dist.integrity verification
• .bin shim creation
• global uninstall cleanup

Not implemented yet:

• lifecycle scripts
• workspaces
• hoisting optimization
• ci mode
• package.json mutation commands

Documentation

The docs app lives in www and includes:

• getting started
• engine backend notes
• package manager behavior

Release Process

This repository is configured for release-plz.

• push regular changes to main
• release-plz opens or updates a release PR
• merging that PR publishes unpublished crates and creates tags/releases

The release workflow expects a CARGO_REGISTRY_TOKEN secret with publish access to crates.io.