Reference

API surface of GasKillerSDK. Inheriting it gives your contract everything on this page.

abstract contract GasKillerSDK is
    StateTracker, TransitionGuard, ERC165, IGasKillerSDK, IGasKillerSDKBatch

Constants

The quorum threshold is not an SDK constant. It belongs to the SchnorrStakeRegistry the target is wired to, as thresholdNum / thresholdDen of the registry's total weight. The public testnet registry requires 2/3.

verifyAndUpdate

The settlement entrypoint. The router builds this call for you (you never encode it by hand), but its parameters explain every failure mode.

function verifyAndUpdate(
    bytes32 msgHash,
    uint32 referenceBlockNumber,
    bytes calldata storageUpdates,
    uint256 transitionIndex,
    bytes4 targetFunction,
    uint256 s,
    address Raddr,
    address[] calldata nonSigners
) external payable;

It executes in this order, so an earlier check masks any later one:

1. referenceBlockNumber < block.number → else FutureBlockNumber
2. referenceBlockNumber + blockStaleMeasure >= block.number → else StaleBlockNumber
3. transitionIndex + 1 == stateTransitionCount() → else InvalidTransitionIndex
4. Digest matches msgHash → else InvalidSignature
5. isValidSignature on the configured registry: subtract each non-signer's key and weight from the aggregate, check the threshold, verify the signature → else InvalidQuorumSignature, or a registry revert
6. Apply the updates

Verification gas doesn't grow with the size of the operator set: one ecrecover against the registry's cached aggregate key, plus one point subtraction per non-signer.

The signed digest

sha256(abi.encode(transitionIndex, address(this), targetFunction, storageUpdates))

Available as a view for off-chain cross-checking:

function getMessageHash(
    uint256 transitionIndex,
    bytes4 targetFunction,
    bytes calldata storageUpdates
) external view returns (bytes32);

Binding address(this) means a payload cannot be replayed against a different contract, and binding transitionIndex means it cannot be replayed against a different state of the same one.

verifyAndUpdateBatch

Settles several independently signed transitions in one transaction. Every transition after the first verifies at warm-access prices.

struct TaskSubmission {
    bytes32 msgHash;
    uint32 referenceBlockNumber;
    bytes storageUpdates;
    uint256 transitionIndex;
    bytes4 targetFunction;
    uint256 s;
    address Raddr;
    address[] nonSigners;
}

function verifyAndUpdateBatch(TaskSubmission[] calldata submissions) external payable;

Each submission is checked exactly as a standalone verifyAndUpdate would check it, so the signed digest does not change when a transition is batched. Submissions apply in order of ascending transitionIndex, and the batch is atomic.

A submission whose index has already settled is skipped rather than reverting the batch. Settlement is permissionless, so without the skip anyone could lift one submission from the mempool, settle it on its own first, and void the rest. Only a gap, meaning an index above the next expected one, reverts with InvalidTransitionIndex.

State update types

storageUpdates decodes to a list of operations applied in order.

Most integrations only ever produce STORE and LOG*. See Tracked functions for the funding rules that apply to the value-bearing types.

Inherited members

From StateTracker:

From TransitionGuard:

Both use fixed hashed slots, and TransitionGuard uses EIP-1153 transient storage, so a Cancun-or-later EVM is required.

Revert selectors

What a failed settlement means. Reverts from the SDK:

Reverts that come from the SchnorrStakeRegistry, not the SDK:

InvalidQuorumSignature

The registry returned false. There are two causes:

• Too few signers. The operators who signed hold less than the threshold share of the registry's weight. This is transient: too many operators missed the round.
• The aggregate doesn't match. The key the registry holds is not the one the operators signed with. If it happens on every task, your target is wired to the wrong registry. If it happens once, the operator set changed mid-round and a new task will settle.

cast call "$TO" "$DATA" --from "$FROM" --block <n> --rpc-url "$RPC_URL"

Source

• gas-killer/solidity-sdk — the SDK
• gas-killer/example-contracts — worked examples of progressively richer targets