Monad Development

Monad Development

For questions not covered here, fetch https://docs.monad.xyz/llms.txt

Quick Reference

Defaults

• Network: Always use testnet (chain ID 10143) unless user says "mainnet"
• Verification: Always verify contracts after deployment unless user says not to
• Framework: Use Foundry (not Hardhat)
• Wallet: If you generate a wallet, MUST persist it (see Wallet Persistence section)

Networks

Docs: https://docs.monad.xyz

Explorers

Agent APIs

IMPORTANT: Do NOT use a browser. Use these APIs directly with curl.

Faucet (Testnet Funding):

curl -X POST https://agents.devnads.com/v1/faucet \
  -H "Content-Type: application/json" \
  -d '{"chainId": 10143, "address": "0xYOUR_ADDRESS"}'

Returns: {"txHash": "0x...", "amount": "1000000000000000000", "chain": "Monad Testnet"}

Fallback (official faucet): https://faucet.monad.xyz If the agent faucet fails, ask the user to fund via the official faucet (do not use a browser yourself).

Verification (All Explorers):

ALWAYS use the verification API first. It verifies on all 3 explorers (MonadVision, Socialscan, Monadscan) with one call. Do NOT use forge verify-contract as first choice.

# 1. Get verification data
forge verify-contract <ADDR> <CONTRACT> \
  --chain 10143 \
  --show-standard-json-input > /tmp/standard-input.json

cat out/<Contract>.sol/<Contract>.json | jq '.metadata' > /tmp/metadata.json
COMPILER_VERSION=$(jq -r '.metadata | fromjson | .compiler.version' out/<Contract>.sol/<Contract>.json)

# 2. Call verification API
STANDARD_INPUT=$(cat /tmp/standard-input.json)
FOUNDRY_METADATA=$(cat /tmp/metadata.json)

cat > /tmp/verify.json << EOF
{
  "chainId": 10143,
  "contractAddress": "0xYOUR_CONTRACT_ADDRESS",
  "contractName": "src/MyContract.sol:MyContract",
  "compilerVersion": "v${COMPILER_VERSION}",
  "standardJsonInput": $STANDARD_INPUT,
  "foundryMetadata": $FOUNDRY_METADATA
}
EOF

curl -X POST https://agents.devnads.com/v1/verify \
  -H "Content-Type: application/json" \
  -d @/tmp/verify.json

With constructor arguments: Add constructorArgs (ABI-encoded, WITHOUT 0x prefix):

ARGS=$(cast abi-encode "constructor(string,string,uint256)" "MyToken" "MTK" 1000000000000000000000000)
ARGS_NO_PREFIX=${ARGS#0x}
# Add to request: "constructorArgs": "$ARGS_NO_PREFIX"

Manual verification fallback (if API fails):

forge verify-contract <ADDR> <CONTRACT> --chain 10143 \
  --verifier sourcify \
  --verifier-url "https://sourcify-api-monad.blockvision.org/"

Wallet Persistence

CRITICAL for agents: If you generate a wallet for the user, you MUST persist it for future use.

When generating a new wallet:

1. Create wallet: cast wallet new
2. Immediately save the address and private key to a secure location
3. Inform the user where the wallet details are stored
4. Fund the wallet via faucet before deployment

Storage options:

• Write to ~/.monad-wallet with chmod 600
• Store in a project-specific .env file (add to .gitignore)
• Return credentials to user and ask them to save securely

Why this matters: Users need access to their wallet to:

• Deploy additional contracts
• Interact with deployed contracts
• Manage funds
• Verify ownership

Deployment Workflow

Use forge script for deployments:

forge script script/Deploy.s.sol:DeployScript \
  --rpc-url https://testnet-rpc.monad.xyz \
  --private-key $PRIVATE_KEY \
  --broadcast

Deploy script template:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.27;
import "forge-std/Script.sol";
import "../src/MyContract.sol";

contract DeployScript is Script {
    function run() external {
        vm.startBroadcast();
        MyContract contract = new MyContract();
        console.log("Contract deployed at:", address(contract));
        vm.stopBroadcast();
    }
}

Technical Details

EVM Version (Critical)

Always set evmVersion: "prague". Requires Solidity 0.8.27+.

Foundry (foundry.toml):

[profile.default]
evm_version = "prague"
solc_version = "0.8.28"

Foundry Tips

Flags that don't exist (don't use):

• --no-commit - not a valid flag for forge init or forge install

Deployment - use forge script, NOT forge create:

forge create --broadcast is buggy and often ignored. Use forge script instead.

forge script script/Deploy.s.sol:DeployScript \
  --rpc-url https://testnet-rpc.monad.xyz \
  --private-key $PRIVATE_KEY \
  --broadcast

Deploy script must NOT hardcode addresses:

// ✅ Correct - reads private key from --private-key flag
function run() external {
    vm.startBroadcast();
    new MyContract();
    vm.stopBroadcast();
}

// ❌ Wrong - hardcodes address, causes "No associated wallet" error
function run() external {
    vm.startBroadcast(0x1234...);
}

Frontend

Import from viem/chains. Do NOT define custom chain:

import { monadTestnet } from "viem/chains";

Use with wagmi:

import { createConfig, http } from 'wagmi'
import { monadTestnet } from 'viem/chains'

const config = createConfig({
  chains: [monadTestnet],
  transports: {
    [monadTestnet.id]: http()
  }
})

Example: Deploy ERC20

1. Create project:

forge init my-token
cd my-token

2. Configure foundry.toml:

[profile.default]
src = "src"
out = "out"
libs = ["lib"]
evm_version = "prague"
solc_version = "0.8.28"

3. Create contract src/MyToken.sol:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.27;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract MyToken is ERC20 {
    constructor(uint256 initialSupply) ERC20("MyToken", "MTK") {
        _mint(msg.sender, initialSupply);
    }
}

4. Install dependencies:

forge install OpenZeppelin/openzeppelin-contracts --no-commit

5. Create deploy script script/Deploy.s.sol:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.27;
import "forge-std/Script.sol";
import "../src/MyToken.sol";

contract DeployScript is Script {
    function run() external {
        vm.startBroadcast();
        MyToken token = new MyToken(1000000 * 10**18);
        console.log("Token deployed at:", address(token));
        vm.stopBroadcast();
    }
}

6. Deploy:

forge script script/Deploy.s.sol:DeployScript \
  --rpc-url https://testnet-rpc.monad.xyz \
  --private-key $PRIVATE_KEY \
  --broadcast

7. Verify:

# Use verification API (verifies on all explorers)
STANDARD_INPUT=$(forge verify-contract <TOKEN_ADDRESS> src/MyToken.sol:MyToken --chain 10143 --show-standard-json-input)
COMPILER_VERSION=$(jq -r '.metadata | fromjson | .compiler.version' out/MyToken.sol/MyToken.json)

curl -X POST https://agents.devnads.com/v1/verify \
  -H "Content-Type: application/json" \
  -d "{
    \"chainId\": 10143,
    \"contractAddress\": \"<TOKEN_ADDRESS>\",
    \"contractName\": \"src/MyToken.sol:MyToken\",
    \"compilerVersion\": \"v${COMPILER_VERSION}\",
    \"standardJsonInput\": $STANDARD_INPUT,
    \"constructorArgs\": \"$(cast abi-encode 'constructor(uint256)' 1000000000000000000000000 | sed 's/0x//')\"
  }"