contracts — zkScatter Docs


import { /* ... */ } from "@zkscatter/sdk/contracts";

These functions wrap proof results in the correct ABI calls. They return ethers TransactionResponse — call .wait() to confirm.

ensureAllowance


async function ensureAllowance(
  signer: Signer,
  token: string,
  spender: string,
  amount: bigint,
): Promise<TransactionResponse[]>

Sets ERC-20 allowance with USDT-safe semantics: if the current allowance is non-zero and not exact, it issues approve(0) first, then approve(amount). Returns one or two pending transactions — await all of them before proceeding.

callDeposit


async function callDeposit(
  signer: Signer,
  poolAddress: string,
  result: DepositProofResult,
  token: string,
  amount: bigint,
): Promise<TransactionResponse>

Submits CommitmentPool.deposit(token, amount, commitment, proof) after ensureAllowance has cleared.

callSettleAuth


async function callSettleAuth(
  signer: Signer,
  settlementAddress: string,
  maker: SettleAuthSide,
  taker: SettleAuthSide,
  fees: SettleAuthFees,
): Promise<TransactionResponse>
 
interface SettleAuthSide {
  proof: Groth16Proof;
  sellToken: string;
  buyToken: string;
  sellAmount: bigint;
  buyAmount: bigint;
  maxFee: bigint;
  expiry: number;
  relayer: string;
  // ...remaining public signals
}
 
interface SettleAuthFees {
  makerFee: bigint;
  takerFee: bigint;
}

Called by relayers, not end users. Both sides must match (token pair flipped, amounts inverse). The contract verifies both Groth16 proofs, records nullifiers, and writes payout commitments.

callClaimWithProof


async function callClaimWithProof(
  signer: Signer,
  settlementAddress: string,
  proof: Groth16Proof,
  inputs: ClaimCallInputs,
): Promise<TransactionResponse>
 
interface ClaimCallInputs {
  recipient: string;
  token: string;
  amount: bigint;
  releaseTime: number;  // 0 = unlocked, else unix seconds
}

callClaimWithProofBatch


async function callClaimWithProofBatch(
  signer: Signer,
  settlementAddress: string,
  items: BatchClaimItem[],  // up to MAX_CLAIM_BATCH_SIZE = 20
): Promise<TransactionResponse>
 
interface BatchClaimItem {
  proof: Groth16Proof;
  inputs: ClaimCallInputs;
}

Atomic — if any claim reverts, the batch reverts. Cap at 20 to stay under typical block gas budgets.

callCancel


async function callCancel(
  signer: Signer,
  settlementAddress: string,
  proof: CancelProofResult,
): Promise<TransactionResponse>

Cancels an active order, advances the maker’s nullifier, and writes a new commitment for the unspent balance.

Common errors

`ERC20: transfer amount exceeds allowance`

ensureAllowance was skipped or the second approve(amount) failed silently. Re-run ensureAllowance before the deposit.

`PrivateSettlement: nullifier reused`

The note has already been spent. Refresh from loadCommitmentInsertedHistory

your nullifier scan to find the next unspent leaf.

`PrivateSettlement: order expired`

expiry < block.timestamp. Generate a fresh authorize proof with a later expiry.