MegaETH Development Skill

What this Skill is for

Use this Skill when the user asks for:

• Foundry project setup targeting MegaETH
• Writing and running tests (unit, fuzz, invariant) on MegaETH
• Deploying and verifying contracts on MegaETH
• Wallet setup and management on MegaETH
• Sending transactions, checking balances, token operations
• Token swaps via Kyber Network aggregator
• MegaETH dApp frontend (React / Next.js with real-time updates)
• RPC configuration and transaction flow optimization
• Smart contract development with MegaEVM considerations
• Storage optimization (transient storage, Solady patterns)
• Gas estimation and fee configuration
• Testing and debugging MegaETH transactions
• WebSocket subscriptions and mini-block streaming
• Bridging ETH from Ethereum to MegaETH
• Privy integration for headless/automated signing
• Ultra-low latency transaction patterns
• ERC-7710 delegations (scoped permissions, spending limits, redelegation chains)
• MetaMask Smart Accounts (ERC-4337 accounts, signers, user operations)
• Advanced permissions (ERC-7715) via MetaMask

Chain Configuration

Default stack decisions (opinionated)

1. Transaction submission: eth_sendRawTransactionSync first

• Use eth_sendRawTransactionSync (EIP-7966) — returns receipt in <10ms
• Eliminates polling for eth_getTransactionReceipt
• Docs: https://docs.megaeth.com/realtime-api

2. RPC: Multicall for eth_call batching (v2.0.14+)

• Prefer Multicall (aggregate3) for batching multiple eth_call requests
• As of v2.0.14, eth_call is 2-10x faster; Multicall amortizes per-RPC overhead
• Still avoid mixing slow methods (eth_getLogs) with fast ones in same request

Note: Earlier guidance recommended JSON-RPC batching over Multicall for caching benefits. With v2.0.14’s performance improvements, Multicall is now preferred.

3. WebSocket: keepalive required

• Send eth_chainId every 30 seconds
• 50 connections per VIP endpoint, 10 subscriptions per connection
• Use miniBlocks subscription for real-time data

4. Storage: slot reuse patterns

• SSTORE 0→non-zero costs 2M gas × multiplier (expensive)
• Use Solady’s RedBlackTreeLib instead of Solidity mappings
• Design for slot reuse, not constant allocation

5. Gas: skip estimation when possible

• Base fee stable at 0.001 gwei, no EIP-1559 adjustment
• Ignore eth_maxPriorityFeePerGas (returns 0)
• Hardcode gas limits to save round-trip
• Always use remote eth_estimateGas (MegaEVM costs differ from standard EVM)

6. Debugging: mega-evme CLI

• Replay transactions with full traces
• Profile gas by opcode
• https://github.com/megaeth-labs/mega-evm

Operating procedure

1. Classify the task layer

• Frontend/WebSocket layer
• RPC/transaction layer
• Smart contract layer
• Testing/debugging layer

2. Pick the right patterns

• Frontend: single WebSocket → broadcast to users (not per-user connections)
• Transactions: sign locally → eth_sendRawTransactionSync → done
• Contracts: check SSTORE patterns, avoid volatile data access limits
• Testing: use mega-evme for replay, Foundry with --skip-simulation
• Delegations: create scoped permissions → sign → share → redeem via eth_sendRawTransactionSync

3. Implement with MegaETH-specific correctness

Always be explicit about:

• Chain ID (4326 mainnet, 6343 testnet)
• Gas limit (hardcode when possible)
• Base fee (0.001 gwei, no buffer)
• Storage costs (new slots are expensive)
• Volatile data limits (20M gas after block.timestamp access)

4. Deliverables expectations

When implementing changes, provide:

• Exact files changed + diffs
• Commands to build/test/deploy
• Gas cost notes for storage-heavy operations
• RPC optimization notes if applicable

Progressive disclosure (read when needed)

• Foundry setup & deploy: foundry-config.md
• Wallet operations: wallet-operations.md
• Frontend patterns: frontend-patterns.md
• Privy integration: privy-integration.md
• RPC methods reference: rpc-methods.md
• Smart contract patterns: smart-contracts.md
• Storage optimization: storage-optimization.md
• Gas model: gas-model.md
• Testing & debugging: testing.md
• Security considerations: security.md
• ERC-7710 delegations: erc7710-delegations.md
• MetaMask Smart Accounts: smart-accounts.md
• Warren Protocol (on-chain websites): warren.md
• Reference links & attribution: resources.md