npx create-eth@latest my-dapp
cd my-dapp && yarn install
yarn fork --network base  # Terminal 1: fork of real chain (or mainnet, your target chain)
yarn deploy               # Terminal 2: deploy contracts

yarn fork --network base  # Terminal 1: fork of real chain (has Uniswap, USDC, etc.)
yarn deploy --watch       # Terminal 2: auto-redeploy on changes
yarn start                # Terminal 3: Next.js at localhost:3000

// Read
const { data } = useScaffoldReadContract({
  contractName: "YourContract",
  functionName: "balanceOf",
  args: [address],
  watch: true,
});

// Write
const { writeContractAsync, isMining } = useScaffoldWriteContract("YourContract");
await writeContractAsync({
  functionName: "swap",
  args: [tokenIn, tokenOut, amount],
  onBlockConfirmation: (receipt) => console.log("Done!", receipt),
});

// Events
const { data: events } = useScaffoldEventHistory({
  contractName: "YourContract",
  eventName: "SwapExecuted",
  fromBlock: 0n,
  watch: true,
});

// ❌ WRONG — key committed to public repo
rpcOverrides: {
  [chains.base.id]: "https://base-mainnet.g.alchemy.com/v2/8GVG8WjDs-LEAKED",
},

// ✅ RIGHT — key stays in .env.local
rpcOverrides: {
  [chains.base.id]: process.env.NEXT_PUBLIC_BASE_RPC || "https://mainnet.base.org",
},

# Check for leaked secrets
git diff --cached --name-only | grep -iE '\.env|key|secret|private'
grep -rn "0x[a-fA-F0-9]\{64\}" packages/ --include="*.ts" --include="*.js" --include="*.sol"
# Check for hardcoded API keys in config files
grep -rn "g.alchemy.com/v2/[A-Za-z0-9]" packages/ --include="*.ts" --include="*.js"
grep -rn "infura.io/v3/[A-Za-z0-9]" packages/ --include="*.ts" --include="*.js"
# If ANYTHING matches, STOP. Move the secret to .env and add .env to .gitignore.

.env
.env.*
*.key
broadcast/
cache/
node_modules/

yarn ipfs
# → https://YOUR_CID.ipfs.cf-ipfs.com

cd packages/nextjs && vercel

packages/
├── foundry/contracts/          # Solidity contracts
├── foundry/script/             # Deploy scripts
├── foundry/test/               # Tests
└── nextjs/
    ├── app/                    # Pages
    ├── components/             # React components
    ├── contracts/
    │   ├── deployedContracts.ts   # AUTO-GENERATED (don't edit)
    │   └── externalContracts.ts   # YOUR external contracts (edit this)
    ├── hooks/scaffold-eth/     # USE THESE hooks
    └── scaffold.config.ts      # Main config

┌─────────────────────────────────────────────────────────────┐
│  1. DISCOVER  Agent queries ERC-8004 IdentityRegistry       │
│               → finds agents with "weather" service tag      │
│                                                              │
│  2. TRUST     Agent checks ReputationRegistry                │
│               → filters by uptime >99%, quality >85          │
│               → picks best-rated weather agent               │
│                                                              │
│  3. CALL      Agent sends HTTP GET to weather endpoint       │
│               → receives 402 Payment Required                │
│               → PAYMENT-REQUIRED header: $0.10 USDC on Base  │
│                                                              │
│  4. PAY       Agent signs EIP-3009 transferWithAuthorization │
│               → retries request with PAYMENT-SIGNATURE       │
│               → server verifies via facilitator              │
│               → payment settled on Base (~$0.001 gas)        │
│                                                              │
│  5. RECEIVE   Server returns 200 OK + weather data           │
│               → PAYMENT-RESPONSE header with tx hash         │
│                                                              │
│  6. RATE      Agent posts feedback to ReputationRegistry     │
│               → value=95, tag="quality", endpoint="..."      │
│               → builds onchain reputation for next caller   │
└─────────────────────────────────────────────────────────────┘

import { x402Fetch } from '@x402/fetch';
import { createWallet } from '@x402/evm';
import { ethers } from 'ethers';

const wallet = createWallet(process.env.AGENT_PRIVATE_KEY);
const provider = new ethers.JsonRpcProvider(process.env.BASE_RPC_URL);

const IDENTITY_REGISTRY = '0x8004A169FB4a3325136EB29fA0ceB6D2e539a432';
const REPUTATION_REGISTRY = '0x8004BAa17C55a88189AE136b182e5fdA19dE9b63';

// 1. Discover: find agents offering weather service
const registry = new ethers.Contract(IDENTITY_REGISTRY, registryAbi, provider);
// Query events or use The Graph subgraph for indexed agent discovery

// 2. Trust: check reputation
const reputation = new ethers.Contract(REPUTATION_REGISTRY, reputationAbi, provider);
const [count, value, decimals] = await reputation.getSummary(
  agentId, trustedClients, "quality", "30days"
);
// Only proceed if value/10^decimals > 85

// 3-5. Pay + Receive: x402Fetch handles the entire 402 flow
const response = await x402Fetch(agentEndpoint, {
  wallet,
  preferredNetwork: 'eip155:8453'
});
const weatherData = await response.json();

// 6. Rate: post feedback onchain
const reputationWriter = new ethers.Contract(REPUTATION_REGISTRY, reputationAbi, signer);
await reputationWriter.giveFeedback(
  agentId, 95, 0, "quality", "weather", agentEndpoint, "", ethers.ZeroHash
);