From 567725788ea80619024ec039213ec13866591189 Mon Sep 17 00:00:00 2001
From: Steven Truong <struong@users.noreply.github.com>
Date: Thu, 6 Aug 2026 12:26:34 -0400
Subject: [PATCH] fix(tempo): included withdrawal fallback nonce

---
 .changeset/tidy-zones-withdraw.md       |  5 ++++
 src/tempo/WithdrawalSenderTag.test-d.ts |  1 +
 src/tempo/WithdrawalSenderTag.test.ts   | 22 +++++++++++-------
 src/tempo/WithdrawalSenderTag.ts        | 31 ++++++++++++++++++++-----
 4 files changed, 44 insertions(+), 15 deletions(-)
 create mode 100644 .changeset/tidy-zones-withdraw.md

diff --git a/.changeset/tidy-zones-withdraw.md b/.changeset/tidy-zones-withdraw.md
new file mode 100644
index 00000000..bc830945
--- /dev/null
+++ b/.changeset/tidy-zones-withdraw.md
@@ -0,0 +1,5 @@
+---
+'ox': patch
+---
+
+Fixed `WithdrawalSenderTag.from` to include the Zone withdrawal fallback nonce.
diff --git a/src/tempo/WithdrawalSenderTag.test-d.ts b/src/tempo/WithdrawalSenderTag.test-d.ts
index 7f817e8f..3154c61d 100644
--- a/src/tempo/WithdrawalSenderTag.test-d.ts
+++ b/src/tempo/WithdrawalSenderTag.test-d.ts
@@ -5,6 +5,7 @@ import { expectTypeOf, test } from 'vp/test'
 test('from', () => {
   expectTypeOf(
     WithdrawalSenderTag.from({
+      fallbackNonce: 19n,
       sender: '0x1234567890abcdef1234567890abcdef12345678',
       transactionHash:
         '0xabababababababababababababababababababababababababababababababab',
diff --git a/src/tempo/WithdrawalSenderTag.test.ts b/src/tempo/WithdrawalSenderTag.test.ts
index d7e3e99e..2679e69b 100644
--- a/src/tempo/WithdrawalSenderTag.test.ts
+++ b/src/tempo/WithdrawalSenderTag.test.ts
@@ -1,22 +1,26 @@
 import { WithdrawalSenderTag } from 'ox/tempo'
 import { expect, test } from 'vp/test'
 
-test('from', () => {
+test('from: production withdrawal', () => {
   const senderTag = WithdrawalSenderTag.from({
-    sender: '0x1234567890abcdef1234567890abcdef12345678',
+    fallbackNonce: 19n,
+    sender: '0x0F0896dbf0465E5c07963301dcFEA1101Fa91EaC',
     transactionHash:
-      '0xabababababababababababababababababababababababababababababababab',
+      '0xae628bdc4bd24a9f9a917825a208baa16c384ab8a96a40cd5146bd20d9b3f6d9',
   })
   expect(senderTag).toMatchInlineSnapshot(
-    `"0x3362fade7333b56b9f3582089ec5915b8a6f6ac13e73a7f90c169e3eb81d8a5e"`,
+    `"0xf1acbae45cd689281144042331e3379cf631a8d2db83057ccf38754a0b0108f2"`,
   )
 })
 
-test('deterministic', () => {
-  const value = {
-    sender: '0x1234567890abcdef1234567890abcdef12345678',
+test('from: internal deposit bounce-back', () => {
+  const senderTag = WithdrawalSenderTag.from({
+    fallbackNonce: 0n,
+    sender: '0x0000000000000000000000000000000000000000',
     transactionHash:
       '0xabababababababababababababababababababababababababababababababab',
-  } as const
-  expect(WithdrawalSenderTag.from(value)).toBe(WithdrawalSenderTag.from(value))
+  })
+  expect(senderTag).toMatchInlineSnapshot(
+    `"0xa86d54e9aab41ae5e520ff0062ff1b4cbd0b2192bb01080a058bb170d84e6457"`,
+  )
 })
diff --git a/src/tempo/WithdrawalSenderTag.ts b/src/tempo/WithdrawalSenderTag.ts
index 49b479c2..2029bcab 100644
--- a/src/tempo/WithdrawalSenderTag.ts
+++ b/src/tempo/WithdrawalSenderTag.ts
@@ -8,8 +8,11 @@ import * as Hex from '../core/Hex.js'
  * `WithdrawalProcessed` event for a Zone withdrawal.
  *
  * The `transactionHash` is the Zone transaction containing the
- * `ZoneOutbox.requestWithdrawal` call. The protocol defines the sender tag as
- * `keccak256(abi.encodePacked(sender, transactionHash))`.
+ * `ZoneOutbox.requestWithdrawal` call. The protocol defines a user withdrawal
+ * sender tag as
+ * `keccak256(abi.encodePacked(sender, transactionHash, fallbackNonce))`.
+ * Internal deposit bounce-backs use the canonical zero-sender tag derived from
+ * `address(0)` and `bytes32(0)` without a fallback nonce.
  *
  * [Authenticated Withdrawals Specification](https://github.com/tempoxyz/zones/blob/main/specs/spec.md#authenticated-withdrawals)
  *
@@ -18,27 +21,43 @@ import * as Hex from '../core/Hex.js'
  * import { WithdrawalSenderTag } from 'ox/tempo'
  *
  * const senderTag = WithdrawalSenderTag.from({
+ *   fallbackNonce: 19n,
  *   sender: '0x1234567890abcdef1234567890abcdef12345678',
  *   transactionHash:
  *     '0xabababababababababababababababababababababababababababababababab'
  * })
  * ```
  *
- * @param value - Withdrawal sender and Zone transaction hash.
+ * @param value - Withdrawal sender, Zone transaction hash, and fallback nonce.
  * @returns The sender tag.
  */
 export function from(value: from.Value): Hex.Hex {
-  const { sender, transactionHash } = value
+  const { fallbackNonce, sender, transactionHash } = value
+  if (
+    sender === '0x0000000000000000000000000000000000000000' &&
+    fallbackNonce === 0n
+  )
+    return Hash.keccak256(
+      AbiParameters.encodePacked(
+        ['address', 'bytes32'],
+        [
+          sender,
+          '0x0000000000000000000000000000000000000000000000000000000000000000',
+        ],
+      ),
+    )
   return Hash.keccak256(
     AbiParameters.encodePacked(
-      ['address', 'bytes32'],
-      [sender, transactionHash],
+      ['address', 'bytes32', 'uint64'],
+      [sender, transactionHash, fallbackNonce],
     ),
   )
 }
 
 export declare namespace from {
   export type Value = {
+    /** Public nonce assigned to the withdrawal's private fallback recipient. */
+    fallbackNonce: bigint
     /** Address that requested the withdrawal. */
     sender: Address.Address
     /** Hash of the Zone transaction containing `ZoneOutbox.requestWithdrawal`. */