Feature: add transaction size limits to chain definitions

[PaulRBerg]

Context

Some chains have transaction size limits that differ from Ethereum mainnet. For example, ZK rollups like zkSync Era have a 131,072 bytes (128 KB) limit on transaction size. This affects applications that batch multiple operations in a single transaction.

Currently, we have to maintain these constants separately in our codebase:

// Our current workaround
export const ZK_TRANSACTION_SIZE_LIMIT = 131_072;

Proposal

Add a txSizeLimit (or similar) property to chain definitions where applicable:

export const zkSync = defineChain({
  id: 324,
  name: 'zkSync Era',
  // ...existing properties
  txSizeLimit: 131_072, // bytes
});

This would allow apps to dynamically query the limit:

import { zkSync } from 'viem/chains';

if (estimatedTxSize > zkSync.txSizeLimit) {
  // Split into multiple transactions
}

Chains that would benefit

• zkSync Era: 131,072 bytes
• Scroll: Has similar ZK-related constraints
• Other ZK rollups and L2s with non-standard limits

Benefits

• Single source of truth for chain-specific limits
• Better DX for apps that need to handle large transactions
• Consistent with viem's existing chain metadata approach (gas limits, block time, etc.)

Would love to hear if this aligns with viem's scope, or if there's a preferred pattern for handling chain-specific constraints like this.