From 4247d7e5c97ce064d08a9170aa43be3cf5f35ae7 Mon Sep 17 00:00:00 2001
From: Abhishek Agrawal <abhishekagrawal080@bitgo.com>
Date: Tue, 14 Apr 2026 03:44:39 +0530
Subject: [PATCH] fix(sdk-coin-sui): handle epoch round trip

TICKET: CSHLD-601
---
 .../mystenlab/builder/TransactionDataBlock.ts | 22 +++++-----
 .../src/lib/mystenlab/types/sui-bcs.ts        |  3 +-
 .../transactionBuilder/transferBuilder.ts     | 41 +++++++++++++++++++
 3 files changed, 53 insertions(+), 13 deletions(-)

diff --git a/modules/sdk-coin-sui/src/lib/mystenlab/builder/TransactionDataBlock.ts b/modules/sdk-coin-sui/src/lib/mystenlab/builder/TransactionDataBlock.ts
index 1bb90d77ba..4cf7fd3099 100644
--- a/modules/sdk-coin-sui/src/lib/mystenlab/builder/TransactionDataBlock.ts
+++ b/modules/sdk-coin-sui/src/lib/mystenlab/builder/TransactionDataBlock.ts
@@ -20,17 +20,6 @@ import { TransactionType, TransactionBlockInput } from './Transactions';
 import { BuilderCallArg, PureCallArg } from './Inputs';
 import { create } from './utils';
 
-export const TransactionExpiration = optional(
-  nullable(
-    union([
-      object({ Epoch: integer() }),
-      object({ None: union([literal(true), literal(null)]) }),
-      object({ ValidDuring: object({ minEpoch: integer(), maxEpoch: integer(), chain: string(), nonce: integer() }) }),
-    ])
-  )
-);
-export type TransactionExpiration = Infer<typeof TransactionExpiration>;
-
 const SuiAddress = string();
 
 const StringEncodedBigint = define<string>('StringEncodedBigint', (val) => {
@@ -44,6 +33,17 @@ const StringEncodedBigint = define<string>('StringEncodedBigint', (val) => {
   }
 });
 
+export const TransactionExpiration = optional(
+  nullable(
+    union([
+      object({ Epoch: StringEncodedBigint }),
+      object({ None: union([literal(true), literal(null)]) }),
+      object({ ValidDuring: object({ minEpoch: integer(), maxEpoch: integer(), chain: string(), nonce: integer() }) }),
+    ])
+  )
+);
+export type TransactionExpiration = Infer<typeof TransactionExpiration>;
+
 const GasConfig = object({
   budget: optional(StringEncodedBigint),
   price: optional(StringEncodedBigint),
diff --git a/modules/sdk-coin-sui/src/lib/mystenlab/types/sui-bcs.ts b/modules/sdk-coin-sui/src/lib/mystenlab/types/sui-bcs.ts
index 9a58c65642..891c512a3a 100644
--- a/modules/sdk-coin-sui/src/lib/mystenlab/types/sui-bcs.ts
+++ b/modules/sdk-coin-sui/src/lib/mystenlab/types/sui-bcs.ts
@@ -123,7 +123,7 @@ export type ValidDuringExpiration = {
  *
  * Indications the expiration time for a transaction.
  */
-export type TransactionExpiration = { None: null } | { Epoch: number } | { ValidDuring: ValidDuringExpiration };
+export type TransactionExpiration = { None: null } | { Epoch: number | bigint | string } | { ValidDuring: ValidDuringExpiration };
 
 // Move name of the Vector type.
 const VECTOR = 'vector';
@@ -155,7 +155,6 @@ const BCS_SPEC: TypeSchema = {
     CallArg: {
       Pure: [VECTOR, BCS.U8],
       Object: 'ObjectArg',
-      ObjVec: [VECTOR, 'ObjectArg'],
       BalanceWithdrawal: 'BalanceWithdrawal',
     },
     TypeTag: {
diff --git a/modules/sdk-coin-sui/test/unit/transactionBuilder/transferBuilder.ts b/modules/sdk-coin-sui/test/unit/transactionBuilder/transferBuilder.ts
index 8fc943cc7c..583ae32ad7 100644
--- a/modules/sdk-coin-sui/test/unit/transactionBuilder/transferBuilder.ts
+++ b/modules/sdk-coin-sui/test/unit/transactionBuilder/transferBuilder.ts
@@ -470,5 +470,46 @@ describe('Sui Transfer Builder', () => {
       const rawTx = tx.toBroadcastFormat();
       should.equal(utils.isValidRawTransaction(rawTx), true);
     });
+
+    it('should round-trip a self-pay transfer with Epoch expiration via fromBytes', async function () {
+      // Regression test for the BigInt round-trip bug:
+      // BCS.U64 deserializes u64 as BigInt, but the previous superstruct schema used integer()
+      // which rejected BigInt, causing fromBytes() to throw a StructError at "expiration".
+      // StringEncodedBigint now accepts string | number | bigint, fixing the round-trip.
+      const gasDataNoPayment = {
+        ...testData.gasDataWithoutGasPayment,
+        payment: [],
+      };
+
+      const txBuilder = factory.getTransferBuilder();
+      txBuilder.type(SuiTransactionType.Transfer);
+      txBuilder.sender(testData.sender.address);
+      txBuilder.send(testData.recipients);
+      txBuilder.gasData(gasDataNoPayment);
+      txBuilder.fundsInAddressBalance(FUNDS_IN_ADDRESS_BALANCE);
+      txBuilder.expiration({ Epoch: 324 }); // number input
+
+      const tx = await txBuilder.build();
+      const rawTx = tx.toBroadcastFormat();
+      should.equal(utils.isValidRawTransaction(rawTx), true);
+
+      // fromBytes must not throw StructError — this was the failing case before the fix
+      should.doesNotThrow(() => {
+        const rebuilder = factory.from(rawTx);
+        should.exist(rebuilder);
+      });
+
+      // Full round-trip: rebuilt tx must serialize identically
+      const rebuilder = factory.from(rawTx);
+      rebuilder.addSignature({ pub: testData.sender.publicKey }, Buffer.from(testData.sender.signatureHex));
+      const rebuiltTx = await rebuilder.build();
+      rebuiltTx.toBroadcastFormat().should.equal(rawTx);
+
+      // Epoch value must survive the round-trip regardless of BigInt/number representation
+      const rebuiltJson = rebuiltTx.toJson();
+      const epochVal = (rebuiltJson.expiration as any)?.Epoch;
+      should.exist(epochVal);
+      Number(epochVal).should.equal(324);
+    });
   });
 });