ERC-8132: Wallet Call Gas Limit Override Capability

Abstract

With the introduction of EIP-5792, apps can now request calls to be batched by a Wallet, but there is no way for an app to set a gas limit for those calls. Gas estimation for EIP-5792 batches is currently fully delegated to the wallet. This proposal introduces a capability that restores the ability for apps to specify a gas limit for calls in an EIP-5792 batch, analogous to the gas parameter of an eth_sendTransaction request.

Motivation

Some calls can have nondeterministic behavior that make it difficult for a wallet to accurately estimate gas limits for them. Apps have the most context around the calls they are making and can provide reasonable gas limits for them.

Specification

One new EIP-5792 wallet capability is defined.

gasLimitOverride Capability

The gasLimitOverride capability is implemented by both apps and wallets.

Wallet Implementation

To conform to this specification, wallets that implement the gasLimitOverride capability:

1. MUST indicate support for the gasLimitOverride capability for all chains (0x0) in their EIP-5792 wallet_getCapabilities response.
2. SHOULD use the app-provided gas limits when processing calls that include them.
3. MUST estimate gas for calls that do not include a gasLimitOverride capability.
4. MAY add additional gas to account for batch processing overhead.
5. MUST return an invalid params error (-32602) if a provided gas limit is zero or exceeds the block gas limit of the target chain.

wallet_getCapabilities Response Specification

type GasLimitOverrideCapability = {
  supported: boolean;
}

wallet_getCapabilities Example Response

{
  "0x0": {
    "gasLimitOverride": {
      "supported": true
    }
  }
}

App Implementation

When an app wants to override the gas limits used for calls in a batch, they SHOULD do this using the gasLimitOverride capability as part of an EIP-5792 wallet_sendCalls call.

This is a call-level capability. Apps MAY specify gas limits for only some calls in a batch; the wallet MUST estimate gas for any calls that do not include a gasLimitOverride capability.

Apps SHOULD only include the gasLimitOverride capability in their wallet_sendCalls requests if they are aware that the wallet supports it (e.g., by checking the wallet_getCapabilities response). Apps MAY include the gasLimitOverride capability with optional: true (as defined in EIP-5792) to ensure compatibility with wallets that do not support this capability.

wallet_sendCalls Gas Limit Override Capability Specification

type GasLimitOverrideParams = {
  value: `0x${string}`; // hex-encoded uint256
}

wallet_sendCalls Example Parameters

[
  {
    "version": "1.0",
    "chainId": "0x01",
    "from": "0xd46e8dd67c5d32be8058bb8eb970870f07244567",
    "calls": [
      {
        "to": "0xd46e8dd67c5d32be8058bb8eb970870f07244567",
        "value": "0x9184e72a",
        "data": "0xd46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675",
        "capabilities": {
          "gasLimitOverride": {
            "value": "0x1234"
          }
        }
      },
      {
        "to": "0xd46e8dd67c5d32be8058bb8eb970870f07244567",
        "value": "0x182183",
        "data": "0xfbadbaf01",
        "capabilities": {
          "gasLimitOverride": {
            "value": "0x765"
          }
        }
      }
    ]
  }
]

The wallet will then account for these provided gas limits when processing the batch of calls.

Rationale

The complexities with applying app-supplied gas limits are discussed briefly in the Rationale section of EIP-5792.

To restate the issue, apps have no context around how calls may or may not be batched by wallets that implement EIP-5792, so they cannot account for any batching overhead. Wallets have low context around the nature of app-provided calls, so they cannot always provide an accurate gas limit.

This proposal allows apps to specify call-level gas limits, and delegates the responsibility of estimating batching overhead (via static analysis or tracing) to the wallet. Gas limit overrides are defined as a capability rather than a core part of EIP-5792 because supporting them requires a wallet to accurately estimate its batching overhead.

Alternative Approaches

Top-level Gas Limit Override Capability

This simplifies the interface somewhat by allowing the app to pass a single gas limit value, but there are a few issues with this approach

1. The app isn’t aware of what batching overhead the wallet might have.
2. Apps would need to sum the call gas limits on their end, which puts more responsibility on the app and more room for error (apps would need to understand that they need to sum gas limits for ALL calls)
3. This wouldn’t be compatible with atomic: false/EOA mode for wallet_sendCalls, where a wallet might be making multiple transactions.

Backwards Compatibility

Backwards compatibility with wallets that do not support this capability is handled by the EIP-5792 capability negotiation mechanism. Apps can check for support via wallet_getCapabilities, or include the capability with optional: true so that unsupported capabilities are ignored rather than rejected.

Security Considerations

• App-provided gas limits that are too low could cause calls to revert. Wallets should consider warning users if a provided gas limit appears insufficient.
• Malicious or misconfigured apps could provide excessively high gas limits. Wallets validate that provided gas limits do not exceed the block gas limit of the target chain, as specified in the Specification section.

Copyright

Copyright and related rights waived via CC0.