Reset SMT Root

Operator-only instruction that rotates the Sparse Merkle Tree by incrementing Instance.current_tree_index and resetting the withdrawal root, allowing a new epoch of 65,536 withdrawals.

The escrow program is migrating from this Sparse Merkle Tree design to an on-chain nonce bitmap (tracked upstream), where this instruction becomes RotateBitmap. This page is accurate against the current escrow program and will be reworked once that change lands.

Accounts

Account	Writable	Signer	Description
`payer`	✓	✓	Fee payer
`operator`		✓	Operator signer
`instance`	✓		Escrow instance PDA (`current_tree_index` incremented)
`operator_pda`			Operator PDA proving the signer is provisioned
`event_authority`			Event authority PDA for `EmitEvent` CPI
`private_channel_escrow_program`			Escrow Program (self-reference for CPI)

Parameters

Parameter	Type	Description
`expected_current_tree_index`	`u64`	Replay guard; must match `Instance.current_tree_index` or the call fails

Returns

Returns a TransactionBuilder that can be used to build and send the transaction.

Example

import { getResetSmtRootInstruction } from "../private-channel-escrow-program/clients/typescript/src/generated";

const resetIx = getResetSmtRootInstruction({
  payer: operatorPayerSigner,
  operator: operatorSigner,
  instance: instancePda,
  operatorPda: operatorPdaAddress,
  eventAuthority: eventAuthorityPda,
  privateChannelEscrowProgram: ESCROW_PROGRAM_ID,
  expectedCurrentTreeIndex: currentTreeIndex // u64
});

Important Notes

Operator-only: requires a valid operator_pda; throws InvalidOperatorPda otherwise
expected_current_tree_index must equal Instance.current_tree_index at call time; a stale value throws UnexpectedTreeIndex, guarding against replaying a reset that already landed
Increments Instance.current_tree_index; nonces valid in the previous tree epoch are invalidated after rotation
The operator-private-channel service calls this automatically when transaction_nonce % 65536 == 0 (and nonce > 0), signaling the start of a new epoch; it should not need to be called manually under normal operation
After rotation, the withdrawal root resets to the empty tree, so new withdrawals start from a fresh SMT
Emits an event via EmitEvent CPI