Prepare a withdrawal with the SDK

Restore the backup first. The client then resolves current membership, checks the note’s spent state, reads the fee, builds the proof, and repeats the mutable checks before returning calldata.

Prepare a withdrawal

import type { HexString, Nullark } from "@nullark/sdk";

type RestoredBundle = Awaited<ReturnType<Nullark["recovery"]["restore"]>>;

export function prepareWithdrawal(input: {
  nullark: Nullark;
  bundle: RestoredBundle;
  childIndex: number;
  destination: HexString;
  maxFeeWei: string;
  minNetAmountWei: string;
}) {
  return input.nullark.withdrawals.prepare({
    bundle: input.bundle,
    childIndex: input.childIndex,
    destination: input.destination,
    maxFeeWei: input.maxFeeWei,
    minNetAmountWei: input.minNetAmountWei
  });
}

Set maxFeeWei and minNetAmountWei from values the user reviewed. Preparation stops when the live fee crosses either bound.

Input	Type	Use
`bundle`	Restored bundle	Private bundle returned by recovery or balance lookup
`childIndex`	`number`	Unspent child selected by the user
`destination`	`HexString`	Full recipient address
`maxFeeWei`	Decimal `string`	Highest fee the user accepts
`minNetAmountWei`	Decimal `string`	Lowest amount the recipient may receive

Review the result

Field	Show or verify
`destination`	Full recipient address
`grossAmountWei`	Selected private note
`feeWei`	Current fee used by the proof
`netAmountWei`	Amount the recipient gets
`transaction.to`	Active runtime pool
`transaction.value`	Always `0` for this withdrawal call

Simulate the unsigned request, submit it once, and retain the returned hash for reconciliation. resolveMembership, isNullifierSpent, and runtimeFeeReadClient must read the same runtime used to restore the bundle. Mixing sources fails the safety assumptions behind the proof.

Workflows

Setup and recovery

Reference

Prepare a withdrawal with the SDK