Add MaxUsedGas field to eth_simulateV1 response

[levin-p]

The eth_simulateV1 RPC method currently returns gasUsed in the call results, but it would be valuable to also include the maxUsedGas field that's already being tracked internally.

Current Behavior
The simCallResult struct in /internal/ethapi/simulate.go currently returns:

 {
    "returnData": "0x...",
    "logs": [...],
    "gasUsed": "0x1234",
    "status": "0x1",
    "error": null
  }

Proposed Enhancement
Add a maxUsedGas field to the response:

{
    "returnData": "0x...",
    "logs": [...],
    "gasUsed": "0x1234",
    "maxUsedGas": "0x5678",
    "status": "0x1",
    "error": null
  }

[s1na]

So you mean the gas usage before refunds? Can you elaborate on the use-case please?

[levin-p]

So you mean the gas usage before refunds? Can you elaborate on the use-case please?

Yes! We have many use cases. If we can utilize the maxUsedGas field, we will benefit greatly.

For example: Approve + Swap Transaction Simulation

In DeFi applications, a common pattern is the "approve + swap" flow where users need to:

1. First approve a token allowance for a DEX contract
2. Then execute the actual swap transaction

Currently, when we want to simulate both transactions together using eth_simulateV1, we can get the gasUsed for each
transaction, but this doesn't give us the peak gas consumption during execution - especially important for the swap
transaction which may have complex gas refund mechanisms.

Why maxUsedGas is needed:

For setting appropriate gas limits on the actual transactions, we need to know the maximum gas consumed during execution
(before any refunds). The current gasUsed field only shows the gas consumption after refunds, which can lead to:

• Underestimating gas limits: If we use gasUsed as the gas limit, transactions might fail due to insufficient gas during
  peak execution
• Safety margin guesswork: We currently have to add arbitrary safety margins (e.g., +25%) which is inefficient

Proposed benefit:

With maxUsedGas, we could:

1. Simulate the approve + swap transactions in batch
2. Apply a safety multiplier (e.g., 1.1x or 1.2x) to the maxUsedGas value to set a more accurate gas limit with
   appropriate buffer
3. Make gas limit calculation more predictable and reliable

This would be particularly valuable for DEX aggregators and wallets that need to provide reliable gas estimates for
complex DeFi operations.