Stylus

A lightweight fork of the Stylus crates from Arbitrum Nitro.

Overview

This repository contains the core Stylus VM components extracted from Nitro, providing a minimal dependency set for Stylus development and integration.

Included Crates

All crates are required dependencies of stylus:

Crate	Description
arbutil	Core utilities and types
brotli	Brotli compression
caller-env	Caller environment for host functions
prover	WASM parsing, config, machine execution
stylus	Main Stylus VM implementation

Building

cargo build --release

Testing

cargo test

Fork Maintenance

Upstream Information

• Repository: https://github.com/OffchainLabs/nitro
• Source Path: crates/
• Current Base: v3.9.5

Merging Upstream Changes

1. Add Upstream Remote (First Time Only)

git remote add upstream https://github.com/OffchainLabs/nitro.git
git fetch upstream --tags

2. Review Changes

# See what changed between tags
git diff v3.9.5..v3.9.6 -- crates/

3. Apply Changes

# Create a branch for the merge
git checkout -b merge-upstream-v3.9.6

# Cherry-pick or manually apply relevant changes

4. Update Documentation

After merging:

1. Update FORK-CHANGES.md with the new base tag
2. Add entry to the Maintenance Log

5. Commit

git commit -m "Merge upstream tag 'vX.Y.Z'"

Crates NOT to Merge

• bench/ - Benchmarking binary
• jit/ - JIT compilation layer
• langs/ - Language binding examples
• validator/ - Validation service
• wasm-testsuite/ - Test suite

Verification After Merge

cargo build --release
cargo test

Directory Structure

stylus/
├── Cargo.toml
├── Cargo.lock
├── README.md
├── FORK-CHANGES.md
└── crates/
    ├── arbutil/
    ├── brotli/
    ├── caller-env/
    ├── prover/
    ├── stylus/
    ├── tools/wasmer/               # Wasmer runtime
    └── wasm-libraries/
        ├── forward/                # Build tool for prover
        └── user-host-trait/        # Host trait for stylus

License

BSL (Business Source License)

Links

• Upstream Nitro Repository
• Arbitrum Documentation
• Stylus Documentation