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+---
+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
+
+| Layer | Tool | Notes |
+|-------|------|-------|
+| Smart contracts (Rust) | `stylus-sdk` v0.10+ | Compiled to WASM, runs on Stylus VM |
+| Smart contracts (Solidity) | Solidity 0.8.x + Foundry | Standard EVM path on Arbitrum |
+| Local node | `nitro-devnode` | Docker-based local Arbitrum chain |
+| Contract CLI | `cargo-stylus` | Check, deploy, export-abi for Stylus |
+| Contract toolchain | Foundry (`forge`, `cast`, `anvil`) | Build, test, deploy, interact for Solidity |
+| Frontend | React / Next.js + viem + wagmi | viem for all chain interaction |
+| Package manager | pnpm | Workspace-friendly, fast |
+
+## 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
+
+```bash
+# 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
+
+```bash
+# 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)
+
+```bash
+# 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)
+
+```typescript
+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