---

name: foundry-setup description: Templates and automation for initializing and configuring Foundry projects. Use when setting up new Foundry projects or adding Foundry to existing codebases.

Foundry Setup Skill

This skill provides templates, scripts, and best practices for setting up Foundry-based Solidity projects.

When to Use

Use this skill when:

• Initializing a new Foundry project
• Adding Foundry to an existing Solidity codebase
• Configuring Foundry settings (optimization, tests, etc.)
• Setting up Foundry in a hybrid Hardhat/Foundry project
• Updating Foundry configuration

Prerequisites: Foundry must be installed (foundryup)

Integration with Framework Detection

Before using this skill, reference the framework-detection skill to:

• Check if Foundry is already configured
• Determine if this is a hybrid setup
• Avoid overwriting existing configuration

Quick Setup

Basic Initialization

# Initialize new Foundry project
forge init my-project
cd my-project

# Or initialize in existing directory
forge init --force

Project Structure

Foundry creates this structure:

project/
├── foundry.toml          # Configuration
├── .env.example          # Environment variables template
├── lib/                  # Dependencies (git submodules)
├── src/                  # Contract source files
│   ├── interfaces        # Interfaces
│   │   └──ICounter       # Example interface
│   └── Counter.sol       # Example contract
├── test/                 # Test files
│   └── Counter.t.sol     # Example test
└── script/               # Deployment scripts
    └── Counter.s.sol     # Example script

Configuration Templates

foundry.toml

See ./templates/foundry.toml for the complete configuration template.

Key Configuration Sections:

[profile.default]
src = "src"
out = "out"
libs = ["lib"]
solc_version = "0.8.30"
optimizer = true
optimizer_runs = 200
via_ir = false

# Testing
verbosity = 2
fuzz_runs = 256

# Gas reporting
gas_reports = ["*"]

# Formatting
line_length = 120
tab_width = 4
bracket_spacing = false

Environment Variables

See ./templates/.env.example for complete environment variable template.

Essential Variables:

# RPC URLs
MAINNET_RPC_URL=
SEPOLIA_RPC_URL=
ARBITRUM_RPC_URL=

# Private Keys (NEVER commit actual keys)
PRIVATE_KEY=

# Etherscan API Keys
ETHERSCAN_API_KEY=
ARBISCAN_API_KEY=

# Gas Price Settings
GAS_PRICE=

Common Configurations

1. High Optimization for Production

[profile.production]
optimizer = true
optimizer_runs = 10000
via_ir = true

2. Detailed Testing

[profile.test]
verbosity = 3
fuzz_runs = 1000
invariant_runs = 256

3. Gas Optimization Focus

[profile.gas-optimized]
optimizer = true
optimizer_runs = 1000000
via_ir = true
gas_reports = ["*"]

4. Mainnet Forking for Tests

[profile.default]
fork_url = "${MAINNET_RPC_URL}"
fork_block_number = 18000000

Dependencies Management

Adding Libraries

# Add OpenZeppelin contracts
forge install OpenZeppelin/openzeppelin-contracts

# Add Solmate
forge install transmissions11/solmate

# Add Forge Standard Library (included by default)
forge install foundry-rs/forge-std

Remappings

Foundry auto-generates remappings.txt, but you can customize:

@openzeppelin/=lib/openzeppelin-contracts/
@solmate/=lib/solmate/src/
forge-std/=lib/forge-std/src/

Or configure in foundry.toml:

remappings = [
    "@openzeppelin/=lib/openzeppelin-contracts/",
    "@solmate/=lib/solmate/src/"
]

Initialization Script

See ./scripts/init-foundry.sh for automated setup.

Usage:

# Basic initialization
./scripts/init-foundry.sh

# With project name
./scripts/init-foundry.sh my-project

# In existing directory
./scripts/init-foundry.sh --force

What the script does:

1. Checks if Foundry is installed
2. Initializes Foundry project
3. Copies configuration templates
4. Sets up .gitignore
5. Installs essential dependencies
6. Creates initial directory structure

Hybrid Setup (Foundry + Hardhat)

When adding Foundry to an existing Hardhat project:

1. Initialize Foundry Without Overwriting

# Initialize but don't overwrite existing files
forge init --no-commit

2. Configure Separate Directories

# foundry.toml
[profile.default]
src = "contracts"          # Use Hardhat's contracts dir
test = "test/foundry"      # Separate Foundry tests
out = "out"
libs = ["node_modules", "lib"]  # Include both package managers

3. Update .gitignore

# Foundry
out/
cache/
lib/

# Hardhat
artifacts/
cache/
node_modules/

4. Install Shared Dependencies

# Install via Foundry
forge install OpenZeppelin/openzeppelin-contracts

# Reference in Hardhat
# Add to hardhat.config.js:
# paths: { sources: "./contracts" }

Testing Setup

Basic Test Structure

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.30;

import "forge-std/Test.sol";
import "../src/MyContract.sol";

contract MyContractTest is Test {
    MyContract public myContract;

    function setUp() public {
        myContract = new MyContract();
    }

    function testBasic() public {
        // Test implementation
    }

    function testFuzz_Amount(uint256 amount) public {
        // Fuzz test
    }
}

Running Tests

# Run all tests
forge test

# Run specific test
forge test --match-test testBasic

# Run with verbosity
forge test -vvvv

# Run with gas reporting
forge test --gas-report

# Run with coverage
forge coverage

Security Best Practices for Private Keys

⚠️ CRITICAL: Never store production private keys in .env files!

Recommended Approaches (in order of preference)

1. Hardware Wallets (Most Secure - Production)

# Deploy using Ledger
forge script script/Deploy.s.sol:DeployScript \
  --rpc-url $RPC_URL \
  --ledger \
  --broadcast

# Deploy using Trezor
forge script script/Deploy.s.sol:DeployScript \
  --rpc-url $RPC_URL \
  --trezor \
  --broadcast

2. Cast Wallet (Recommended - Development & Production)

Create a named keystore:

# Create a new wallet (prompts for password)
cast wallet new ~/.foundry/keystores/deployer

# Import existing private key into keystore
cast wallet import deployer --interactive

Use in deployment:

# Deploy using named account
forge script script/Deploy.s.sol:DeployScript \
  --rpc-url $RPC_URL \
  --account deployer \
  --sender 0xYourAddress \
  --broadcast

Update your script to use the account:

contract DeployScript is Script {
    function run() external {
        // No private key needed - uses --account flag
        vm.startBroadcast();

        MyContract myContract = new MyContract();

        vm.stopBroadcast();

        console.log("MyContract deployed to:", address(myContract));
    }
}

3. Interactive Private Key (Development Only)

# Prompts for private key (not stored anywhere)
forge script script/Deploy.s.sol:DeployScript \
  --rpc-url $RPC_URL \
  --private-key-interactive \
  --broadcast

4. .env Variables (Development/Testing ONLY)

⚠️ Use ONLY for local development or testnet testing with non-production keys!

contract DeployScript is Script {
    function run() external {
        uint256 deployerPrivateKey = vm.envUint("PRIVATE_KEY");

        vm.startBroadcast(deployerPrivateKey);

        MyContract myContract = new MyContract();

        vm.stopBroadcast();

        console.log("MyContract deployed to:", address(myContract));
    }
}

If using .env:

• ✅ Only use accounts created specifically for development/testing
• ✅ Never reuse production private keys
• ✅ Keep test funds minimal
• ✅ Add .env to .gitignore
• ❌ Never commit .env to version control
• ❌ Never use for mainnet deployments

Deployment Setup

Deploy Commands

# Dry run (simulation)
forge script script/Deploy.s.sol:DeployScript --rpc-url $RPC_URL

# Actual deployment with hardware wallet (RECOMMENDED for production)
forge script script/Deploy.s.sol:DeployScript \
  --rpc-url $RPC_URL \
  --ledger \
  --broadcast \
  --verify

# Actual deployment with cast wallet (RECOMMENDED for all deployments)
forge script script/Deploy.s.sol:DeployScript \
  --rpc-url $RPC_URL \
  --account deployer \
  --sender 0xYourAddress \
  --broadcast \
  --verify

# Development only: with .env private key
forge script script/Deploy.s.sol:DeployScript \
  --rpc-url $RPC_URL \
  --broadcast \
  --verify

Best Practices

1. Secure private key management - Use hardware wallets or cast wallet for all deployments; never store production keys in .env
2. Use profiles - Create different profiles for dev, test, production
3. High optimizer runs for production - Use 10,000+ optimizer runs for deployed contracts
4. Comprehensive .env.example - Document all required environment variables (but discourage private keys)
5. Git submodules for deps - Let Foundry manage dependencies via git
6. Separate test directories - Use test/foundry/ for Foundry tests in hybrid setups
7. Enable via-ir for optimization - Use via_ir = true for complex contracts
8. Version pin Solidity - Specify exact solc_version in foundry.toml

Troubleshooting

Issue: "forge: command not found"

# Install/update Foundry
curl -L https://foundry.paradigm.xyz | bash
foundryup

Issue: Dependency conflicts in hybrid setup

# Prioritize Foundry libs over node_modules
libs = ["lib", "node_modules"]

Issue: Compilation errors with remappings

# Regenerate remappings
forge remappings > remappings.txt

Issue: Tests not found

# Check test file naming (must end in .t.sol)
mv test/MyTest.sol test/MyTest.t.sol

Quick Reference

Task	Command	Notes
Init project	forge init	Creates new project
Add dependency	forge install <repo>	Uses git submodules
Build	forge build	Compiles contracts
Test	forge test	Runs tests
Coverage	forge coverage	Test coverage
Gas report	forge test --gas-report	Gas usage
Format	forge fmt	Code formatting
Deploy	forge script	Run deployment
Verify	forge verify-contract	Verify on Etherscan

Template Files

This skill provides the following templates:

• ./templates/foundry.toml - Complete Foundry configuration
• ./templates/.env.example - Environment variables template

Scripts

This skill provides the following scripts:

• ./scripts/init-foundry.sh - Automated project initialization

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Next Steps After Setup:

1. Configure foundry.toml for your specific needs
2. Copy .env.example to .env and fill in values
3. Install required dependencies with forge install
4. Write contracts in src/
5. Write tests in test/
6. Run forge test to verify setup