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Overview

The CoW Protocol Contracts project uses a hybrid build system that compiles both Solidity smart contracts and TypeScript bindings. The build process is managed through npm scripts and uses Hardhat as the development environment.
This repository is migrating to Foundry. For Hardhat-based development, refer to the v1 branch.

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Prerequisites

Before building the project, ensure you have:
  • Node.js (v16 or higher recommended)
  • Yarn package manager
  • Git

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Installation

1

Clone the repository

git clone https://github.com/cowprotocol/contracts.git
cd contracts
2

Install dependencies

yarn
3

Build the project

yarn build

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Build Commands

The project provides several build commands for different purposes: 
yarn build

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Build Script Details

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yarn build

Executes the complete build process:
  1. Compiles Solidity contracts with Hardhat
  2. Generates TypeScript bindings
  3. Compiles TypeScript in three configurations (ESM, CommonJS, and default)
This is equivalent to running: 
yarn build:sol && yarn build:ts

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yarn build:sol

Compiles all Solidity smart contracts using Hardhat with the --force flag to ensure a clean build: 
hardhat compile --force
The Solidity compiler settings are optimized for production:
  • Optimizer: Enabled
  • Optimizer runs: 1,000,000
  • EVM version: Cancun
  • IR compilation: Disabled

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yarn build:ts

Compiles TypeScript files in multiple module formats: 
tsc && tsc -p tsconfig.lib.esm.json && tsc -p tsconfig.lib.commonjs.json
This generates:
  • Default TypeScript output
  • ESM (ECMAScript Modules) build in lib/esm/
  • CommonJS build in lib/commonjs/

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Compiler Configuration

The project uses Foundry’s configuration system with settings optimized for gas efficiency: 
[profile.default]
src = "src"
out = "out"
libs = ["node_modules", "lib"]

via_ir = false
optimizer = true
optimizer_runs = 1000000
evm_version = "cancun"
The optimizer is configured with 1,000,000 runs, which prioritizes minimal gas costs for contract execution over deployment costs.

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Output Structure

After a successful build, you’ll find:
  • Compiled contracts: out/ directory (Foundry) or contract artifacts
  • TypeScript ESM: lib/esm/ directory
  • TypeScript CommonJS: lib/commonjs/ directory
  • Type definitions: .d.ts files alongside compiled JavaScript

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Linting

The project includes comprehensive linting for both Solidity and TypeScript: 
yarn lint

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Formatting

Code formatting is available for both Solidity and TypeScript: 
# Format Solidity contracts
yarn fmt:sol

# Format TypeScript files
yarn fmt:ts

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Troubleshooting

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Build Failures

If you encounter build errors:
  1. Clean the build artifacts: 
    rm -rf out/ lib/ cache/
  2. Reinstall dependencies: 
    rm -rf node_modules/
yarn
  3. Force rebuild: 
    yarn build:sol
yarn build:ts

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Compiler Version Issues

Ensure your Solidity compiler version matches the project requirements. The project uses Hardhat’s built-in compiler management.

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Next Steps

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