# Deploy Solidity Contracts

This guide covers deploying Solidity smart contracts on Rome EVM using Hardhat and Foundry.

## Prerequisites

* Node.js v18+ (Hardhat) or Foundry installed
* A funded Rome EVM address (see [Quickstart](/getting-started/quickstart.md))
* Your private key exported as an environment variable

```bash
export PRIVATE_KEY="0xYOUR_PRIVATE_KEY"
```

## Network Configuration

| Network           | RPC URL                                      | Chain ID |
| ----------------- | -------------------------------------------- | -------- |
| Local             | `http://localhost:9090`                      | `1001`   |
| Devnet (montispl) | `https://montispl.devnet.romeprotocol.xyz`   | `200002` |
| Testnet (Martius) | `https://martius-i.testnet.romeprotocol.xyz` | `121214` |
| Testnet (Caelian) | `https://caelian-i.testnet.romeprotocol.xyz` | `121215` |

## Hardhat

### Setup

```bash
mkdir my-rome-project && cd my-rome-project
npm init -y
npm install --save-dev hardhat @nomicfoundation/hardhat-toolbox
npx hardhat init
```

### hardhat.config.js

```javascript
require("@nomicfoundation/hardhat-toolbox");

module.exports = {
  solidity: {
    version: "0.8.28",
    settings: {
      optimizer: { enabled: true, runs: 200 },
    },
  },
  networks: {
    rome_local: {
      url: "http://localhost:9090",
      chainId: 1001,
      accounts: [process.env.PRIVATE_KEY],
    },
    rome_devnet: {
      url: "https://montispl.devnet.romeprotocol.xyz",
      chainId: 200002,
      accounts: [process.env.PRIVATE_KEY],
    },
    rome_martius: {
      url: "https://martius-i.testnet.romeprotocol.xyz",
      chainId: 121214,
      accounts: [process.env.PRIVATE_KEY],
    },
    rome_caelian: {
      url: "https://caelian-i.testnet.romeprotocol.xyz",
      chainId: 121215,
      accounts: [process.env.PRIVATE_KEY],
    },
  },
};
```

### Deploy

```bash
npx hardhat run scripts/deploy.js --network rome_devnet
```

### Verify on Block Explorer

```bash
npx hardhat verify --network rome_martius 0xCONTRACT_ADDRESS
```

## Foundry

### Setup

```bash
forge init my-rome-project
cd my-rome-project
```

### Deploy

```bash
# Local
forge create --rpc-url http://localhost:9090 \
  --private-key $PRIVATE_KEY \
  src/Counter.sol:Counter

# Devnet
forge create --rpc-url https://montispl.devnet.romeprotocol.xyz \
  --private-key $PRIVATE_KEY \
  src/Counter.sol:Counter
```

### Call Deployed Contract

```bash
# Read
cast call 0xCONTRACT_ADDRESS "number()" \
  --rpc-url https://montispl.devnet.romeprotocol.xyz

# Write
cast send 0xCONTRACT_ADDRESS "increment()" \
  --rpc-url https://montispl.devnet.romeprotocol.xyz \
  --private-key $PRIVATE_KEY
```

## Using the Rome Solidity SDK

For contracts that interact with Solana programs, install the Rome Solidity SDK:

```bash
npm install @rome-protocol/solidity-sdk
```

```solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.28;

import {SplToken, CpiProgram, SystemProgram} from "@rome-protocol/solidity-sdk/contracts/core/Precompiles.sol";
import {SPL_ERC20} from "@rome-protocol/solidity-sdk/contracts/token/ERC20SPL.sol";
import {RomeEVMAccount} from "@rome-protocol/solidity-sdk/contracts/core/RomeEVMAccount.sol";

contract MyRomeContract {
    // Read user's SPL token balance from Solana
    function getSolanaBalance(bytes32 mint) external view returns (uint64) {
        bytes32 userPda = RomeEVMAccount.pda(msg.sender);
        ISplToken.Account memory account = SplToken.account_state(userPda);
        return account.amount;
    }

    // Invoke any Solana program via CPI
    function callSolanaProgram(
        bytes32 programId,
        ICrossProgramInvocation.AccountMeta[] calldata accounts,
        bytes calldata data
    ) external {
        CpiProgram.invoke(programId, accounts, data);
    }
}
```

## Deployment Constraints

| Constraint             | Limit              | Notes                                                        |
| ---------------------- | ------------------ | ------------------------------------------------------------ |
| Max contract size      | 480 KB             | Raised from Ethereum's 24 KB for OP-Geth mode                |
| Transaction size limit | 80 KB per holder   | Large deploys are split across holder accounts transparently |
| Compute budget         | \~1.4M CU (atomic) | Use iterative mode for heavy contracts                       |
| Solidity version       | 0.8.28 recommended | Earlier versions work but 0.8.28 matches the SDK             |

## Common Errors

| Error                        | Cause                      | Fix                                              |
| ---------------------------- | -------------------------- | ------------------------------------------------ |
| `insufficient funds for gas` | EVM address has no balance | Deposit SOL via the deposit UI                   |
| `nonce too low`              | Stale nonce in wallet      | Reset MetaMask account or specify nonce manually |
| `execution reverted`         | Contract logic failed      | Debug with `eth_call` or `forge test --fork-url` |
| `transaction underpriced`    | Gas price below minimum    | Increase gas price in transaction                |

## What's Next

* [Call Solana from EVM](/developer-guides/call-solana-from-evm.md) — use CPI precompiles to interact with Solana programs
* [Token Wrapping](https://github.com/rome-protocol/docs/blob/main/developer-guides/token-wrapping.md) — deploy ERC-20 wrappers for SPL tokens
* [CU Optimization](https://github.com/rome-protocol/docs/blob/main/developer-guides/cu-optimization.md) — reduce compute unit consumption


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