name: arbitrum-dapp-skill description: Opinionated guide for building dApps on Arbitrum using Stylus (Rust) and/or Solidity. Covers local devnode setup, contract development, testing, deployment, and React frontend integration with viem. Use when starting a new Arbitrum project, writing Stylus or Solidity contracts, deploying to Arbitrum, or building a frontend that interacts with Arbitrum contracts.

Arbitrum dApp Development

Stack

Decision Flow

When starting a new contract:

1. Need max performance / lower gas? → Stylus Rust. See references/stylus-rust-contracts.md.
2. Need broad tooling compatibility / rapid prototyping? → Solidity. See references/solidity-contracts.md.
3. Hybrid? → Use both. Stylus and Solidity contracts are fully interoperable on Arbitrum.

Project Scaffolding

Monorepo layout (recommended)

my-arbitrum-dapp/
├── apps/
│   ├── frontend/            # React / Next.js app
│   ├── contracts-stylus/    # Rust Stylus contracts
│   ├── contracts-solidity/  # Foundry Solidity contracts
│   └── nitro-devnode/       # Local dev chain (git submodule)
├── pnpm-workspace.yaml
└── package.json

Bootstrap steps

# 1. Create workspace
mkdir my-arbitrum-dapp && cd my-arbitrum-dapp
pnpm init
printf "packages:\n  - 'apps/*'\n" > pnpm-workspace.yaml

# 2. Local devnode
git clone https://github.com/OffchainLabs/nitro-devnode.git apps/nitro-devnode
cd apps/nitro-devnode && ./run-dev-node.sh && cd ../..

# 3a. Stylus contract
cargo stylus new apps/contracts-stylus

# 3b. Solidity contract
cd apps && forge init contracts-solidity && cd ..

# 4. Frontend
pnpm create next-app apps/frontend --typescript
cd apps/frontend
pnpm add viem wagmi @tanstack/react-query

Core Workflow

Stylus Rust

# Validate
cargo stylus check --endpoint http://localhost:8547

# Deploy (uses the nitro-devnode pre-funded deployer account)
cargo stylus deploy \
  --endpoint http://localhost:8547 \
  --private-key $PRIVATE_KEY

# Export ABI for frontend consumption
cargo stylus export-abi

Solidity (Foundry)

# Build
forge build

# Test
forge test

# Deploy locally (uses the nitro-devnode pre-funded deployer account)
forge script script/Deploy.s.sol --rpc-url http://localhost:8547 --broadcast \
  --private-key $PRIVATE_KEY

Note: The nitro-devnode ships with a pre-funded deployer account. See references/local-devnode.md for the default private key and address. For testnet/mainnet, use your own key via environment variables — never hardcode secrets.

Frontend (viem + wagmi)

import { createPublicClient, http } from "viem";
import { arbitrumSepolia } from "viem/chains";

const client = createPublicClient({
  chain: arbitrumSepolia,
  transport: http(),
});

// Read from contract
const result = await client.readContract({
  address: "0x...",
  abi: contractAbi,
  functionName: "myFunction",
});

See references/frontend-integration.md for full patterns with wagmi hooks, wallet connection, and write transactions.

Principles

• Always use viem for chain interaction.
• Test locally first against nitro-devnode before deploying to testnet.
• Export ABIs from both Stylus (cargo stylus export-abi) and Solidity (forge inspect) and keep them in a shared location the frontend can import.
• Use environment variables for RPC URLs, contract addresses, and private keys. Never hardcode secrets.
• Stylus contracts are EVM-compatible — they share the same address space, storage model, and ABI encoding as Solidity contracts. Cross-contract calls work seamlessly.

References

Load these as needed for deeper guidance:

• references/stylus-rust-contracts.md — Stylus SDK patterns, storage, macros, entrypoints
• references/solidity-contracts.md — Solidity on Arbitrum specifics and Foundry workflow
• references/frontend-integration.md — React + viem + wagmi patterns
• references/local-devnode.md — Nitro devnode setup, accounts, and debugging
• references/deployment.md — Deploying to testnet and mainnet
• references/testing.md — Testing strategies for both Stylus and Solidity