Transient storage for claims gate

[naddison36]

Summary

• Upgrade Solidity from 0.8.23 to 0.8.36.
• Target the Cancun EVM version.
• Use transient storage for the claimingEtherFi guard in:
  • EtherFiAssetAdapter
  • WeETHAssetAdapter

The guard is declared as:

bool internal transient claimingEtherFi;

It is only needed while redeem calls Ether.fi's batchClaimWithdraw:

claimingEtherFi = true;
etherfiWithdrawalNFT.batchClaimWithdraw(requestIds);
claimingEtherFi = false;

The adapters’ receive functions use it to reject ETH sent outside an adapter-initiated claim:

receive() external payable {
    if (!claimingEtherFi) {
        revert UnauthorizedEtherFiClaim();
    }
}

Using transient storage avoids writing and clearing a persistent storage slot while preserving the existing authorization behavior.

Gas savings

Gas was measured with Solidity 0.8.36, targeting Cancun, using gasleft() immediately before and after the redeem call. Request setup was excluded from the measurement.

Adapter	Requests claimed	Persistent storage	Transient storage	Gas saved
EtherFi	1	140,456	118,560	21,896
EtherFi	2	150,306	128,409	21,897
EtherFi	5	179,865	157,965	21,900
weETH	1	140,857	118,964	21,893
weETH	2	151,111	129,217	21,894
weETH	5	181,882	159,985	21,897

This saves approximately 21,900 gas per Ether.fi redemption transaction, independent of the number of requests claimed in the batch.

Testing

• Full Foundry build with Solidity 0.8.36
• EtherFiAssetAdapter unit tests
• WeETHAssetAdapter unit tests
• Hardhat compilation targeting Cancun

[sparrowDom]

LGTM