Approvals - DZap

Before any swap/bridge/zap that spends ERC20s, a spender must be approved. The SDK supports several modes via getAllowance(), approve(), and sign() — pick AutoPermit unless you have a reason not to.

The modes

approve()’s mode param takes an ApprovalModes value; sign()’s permitType param takes a PermitTypes value. They’re closely related but not identical sets:

`ApprovalModes` (for `approve()`)	`PermitTypes` (for `sign()`)	How	Spender
`Default`	—	Standard ERC20 `approve()` transaction	DZap router
`PermitSingle`	`PermitSingle`	One-time approve to Permit2; sign a single-token Permit2 permit per trade	Permit2 contract
`PermitWitnessTransferFrom`	`PermitWitnessTransferFrom`	One-time approve to Permit2; sign a witness-bound Permit2 transfer per trade	Permit2 contract
`PermitBatchWitnessTransferFrom`	`PermitBatchWitnessTransferFrom`	One-time approve to Permit2; sign one batched permit covering multiple tokens	Permit2 contract
—	`EIP2612Permit`	Sign the token’s native EIP-2612 permit message; no approval transaction at all	DZap router
`AutoPermit`	`AutoPermit`	EIP-2612 if the token supports it, otherwise falls back to Permit2	Auto

Most modern tokens support EIP-2612 or are routable through Permit2, so AutoPermit covers the long tail. ApprovalModes has no EIP2612Permit member — a token that supports EIP-2612 never needs an approve() call at all, only a sign() call.

Check allowance

import { ApprovalModes, Services } from '@dzapio/sdk';

const { status, data } = await dzap.getAllowance({
  chainId: 42161,
  sender: '0xUser',
  tokens: [{ address: '0xaf88d065e77c8cC2239327C5EDb3A432268e5831', amount: '1000000' }],
  service: Services.trade, // 'trade' | 'dca' | 'zap'
  mode: ApprovalModes.AutoPermit,
});

// data['0xaf88...'] => { allowance: bigint, type: 'dzap' | 'permit2' | 'eip2612' }

type tells you whether the token will use a direct DZap approval, a Permit2 approval, or an EIP-2612 permit. There is no approvalNeeded/signatureNeeded field — derive that yourself:

const entry = data['0xaf88d065e77c8cC2239327C5EDb3A432268e5831'];
const needsApproval = entry.type !== 'eip2612' && entry.allowance < BigInt('1000000');
const needsSignature = entry.type !== 'dzap'; // permit2 and eip2612 both require a per-trade signature

Approve

if (needsApproval) {
  await dzap.approve({
    chainId: 42161,
    signer: walletClient,
    sender: '0xUser',
    tokens: [{ address: '0xaf88d065e77c8cC2239327C5EDb3A432268e5831', amount: '1000000' }],
    service: Services.trade,
    mode: ApprovalModes.AutoPermit,
    approvalTxnCallback: async ({ txnDetails, address }) => {
      // txnDetails: { txnHash: string; code: StatusCodes; status: TxnStatus }
      console.log('approval', address, txnDetails.status, txnDetails.txnHash);
    },
  });
}

approvalTxnCallback fires once per token (viem WalletClient signers only). If it returns a TxnStatus other than success, remaining tokens in the batch are skipped.

Sign (gasless permits)

For Permit2/EIP-2612 paths — returns the permit response directly, not wrapped in .data:

import { PermitTypes } from '@dzapio/sdk';

if (needsSignature) {
  const result = await dzap.sign({
    chainId: 42161,
    sender: '0xUser',
    tokens: [{ address: '0xaf88d065e77c8cC2239327C5EDb3A432268e5831', amount: '1000000' }],
    service: Services.trade,
    signer: walletClient,
    permitType: PermitTypes.AutoPermit,
  });

  if (result.status === 'success') {
    if ('batchPermitData' in result) {
      // PermitBatchWitnessTransferFrom → single encoded payload covering all tokens
      console.log(result.batchPermitData);
    } else {
      // Every other permitType → per-token entries
      result.tokens.forEach((t) => console.log(t.address, t.permitData));
    }
  }
}

Recommended flow

Check

getAllowance() with mode: AutoPermit, then derive needsApproval/needsSignature from allowance/type as shown above.

Approve or sign

If needsApproval: approve(). If needsSignature: sign().

Execute

Pass the resulting permitData (per-token) into the matching data[].permitData field of your trade()/zap() request.

Common pitfalls

Multi-token operations — getAllowance and approve both accept arrays. Don’t loop one-by-one; you’ll trigger N wallet popups.
Service must match — service: Services.trade checks the trade router; service: Services.zap checks the zap router. They differ on some chains. Services only has trade, dca, and zap — there is no 'swap' value.
Permit deadlines — gasless permits include a deadline. Sign close to execution.

​The modes

​Check allowance

​Approve

​Sign (gasless permits)

​Recommended flow

​Common pitfalls