Ethereum Development Skill

Master Ethereum development including EVM internals, gas optimization, transaction mechanics, and client interactions.

Quick Start

# Invoke this skill for Ethereum development
Skill("ethereum-development", topic="gas", network="mainnet")

Topics Covered

1. EVM (Ethereum Virtual Machine)

Understand the execution environment:

• Stack Machine: 256-bit words, 1024 depth
• Memory: Linear byte array, expansion costs
• Storage: Persistent key-value, 32-byte slots
• Opcodes: Costs, effects, gas consumption

2. Gas Optimization

Reduce transaction costs:

• Storage Packing: Fit multiple values in one slot
• Calldata vs Memory: Choose efficiently
• Loop Optimization: Cache storage reads
• Custom Errors: Save gas on reverts

3. Transaction Mechanics

Master transaction lifecycle:

• Types: Legacy (0), Access List (1), EIP-1559 (2)
• Fee Estimation: Base fee, priority fee, max fee
• Nonce Management: Sequential ordering
• Receipts: Status, logs, gas used

4. Client Interactions

Work with Ethereum nodes:

• RPC Methods: eth_, debug_, trace_
• State Queries: Storage slots, code, balance
• Event Subscriptions: Filter logs, topics

Code Examples

Gas-Efficient Storage

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

contract Optimized {
    // Pack into single slot (32 bytes)
    struct User {
        uint128 balance;    // 16 bytes
        uint64 lastUpdate;  // 8 bytes
        uint32 nonce;       // 4 bytes
        bool active;        // 1 byte
        // 3 bytes padding
    }

    mapping(address => User) public users;
}

Read Storage Slot

import { createPublicClient, http, keccak256, encodePacked, pad } from 'viem';
import { mainnet } from 'viem/chains';

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

// Read mapping value: balances[address]
async function getBalance(contract: `0x${string}`, user: `0x${string}`) {
  const slot = keccak256(encodePacked(['address', 'uint256'], [user, 0n]));
  return await client.getStorageAt({ address: contract, slot });
}

EIP-1559 Transaction

import { createWalletClient, http, parseEther } from 'viem';

const client = createWalletClient({ transport: http() });

const hash = await client.sendTransaction({
  to: '0x...',
  value: parseEther('0.1'),
  type: 'eip1559',
  maxFeePerGas: parseGwei('30'),
  maxPriorityFeePerGas: parseGwei('2'),
});

Gas Optimization Cheatsheet

Common Pitfalls

Troubleshooting

"Transaction underpriced"

# Check current gas prices
cast gas-price --rpc-url $RPC
cast basefee --rpc-url $RPC

Set maxFeePerGas to at least 2x current base fee.

"Out of gas"

# Trace transaction to find issue
cast run --trace $TX_HASH --rpc-url $RPC

"Nonce too low"

# Get current nonce
cast nonce $ADDRESS --rpc-url $RPC

CLI Commands

# Foundry essentials
forge build --sizes          # Contract sizes
forge test --gas-report      # Gas consumption
forge snapshot               # Gas snapshots
cast storage $ADDR $SLOT     # Read storage
cast call $ADDR "fn()"       # Simulate call

Test Template

contract GasTest is Test {
    function test_GasOptimization() public {
        uint256 gasBefore = gasleft();
        target.optimizedFunction();
        uint256 gasUsed = gasBefore - gasleft();

        assertLt(gasUsed, 50000, "Too much gas used");
    }
}

Cross-References

• Bonded Agent: 02-ethereum-development
• Related Skills: solidity-development, web3-frontend

Version History