From c139f7f4917b2224121718c25831a3307fc3dc73 Mon Sep 17 00:00:00 2001
From: Abhishek Agrawal <abhishekagrawal080@bitgo.com>
Date: Tue, 7 Jul 2026 14:05:22 +0530
Subject: [PATCH] fix(sdk-coin-sui): keep token coin type on addr-balance
 rebuild

TICKET: CSHLD-1146
---
 .../src/lib/tokenTransferBuilder.ts           | 28 ++++++++++++++++++-
 .../tokenTransferBuilder.ts                   | 26 +++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/modules/sdk-coin-sui/src/lib/tokenTransferBuilder.ts b/modules/sdk-coin-sui/src/lib/tokenTransferBuilder.ts
index ee45697964..5c7b36d06a 100644
--- a/modules/sdk-coin-sui/src/lib/tokenTransferBuilder.ts
+++ b/modules/sdk-coin-sui/src/lib/tokenTransferBuilder.ts
@@ -5,13 +5,14 @@ import { SuiTransaction, SuiTransactionType, TokenTransferProgrammableTransactio
 import { Transaction } from './transaction';
 import { TransactionBuilder } from './transactionBuilder';
 import { TokenTransferTransaction } from './tokenTransferTransaction';
-import { SuiObjectRef } from './mystenlab/types';
+import { normalizeSuiAddress, SuiObjectRef } from './mystenlab/types';
 import utils from './utils';
 import {
   Inputs,
   TransactionBlock as ProgrammingTransactionBlockBuilder,
   TransactionArgument,
 } from './mystenlab/builder';
+import { TypeTagSerializer } from './mystenlab/txn-data-serializers/type-tag-serializer';
 import BigNumber from 'bignumber.js';
 
 export class TokenTransferBuilder extends TransactionBuilder<TokenTransferProgrammableTransaction> {
@@ -25,6 +26,15 @@ export class TokenTransferBuilder extends TransactionBuilder<TokenTransferProgra
    */
   protected _fundsInAddressBalance: BigNumber = new BigNumber(0);
 
+  /**
+   * Coin type recovered from a deserialized transaction (the `redeem_funds` type argument /
+   * `BalanceWithdrawal` type). When set it takes precedence over the coin type derived from the
+   * coin config, so re-building a transaction (e.g. to attach a TSS signature before broadcast)
+   * preserves the exact coin type it was signed with even when the builder was constructed with
+   * the parent chain config rather than the token config.
+   */
+  protected _tokenCoinTypeOverride?: string;
+
   constructor(_coinConfig: Readonly<CoinConfig>) {
     super(_coinConfig);
     this._transaction = new TokenTransferTransaction(_coinConfig);
@@ -38,6 +48,9 @@ export class TokenTransferBuilder extends TransactionBuilder<TokenTransferProgra
    * The full coin type string derived from the coin config (e.g. `0xabc::my_token::MY_TOKEN`).
    */
   private get tokenCoinType(): string {
+    if (this._tokenCoinTypeOverride) {
+      return this._tokenCoinTypeOverride;
+    }
     const config = this._coinConfig as SuiCoin;
     return `${config.packageId}::${config.module}::${config.symbol}`;
   }
@@ -113,6 +126,19 @@ export class TokenTransferBuilder extends TransactionBuilder<TokenTransferProgra
     if (withdrawalInput) {
       const bw = withdrawalInput.BalanceWithdrawal ?? withdrawalInput.value?.BalanceWithdrawal;
       this._fundsInAddressBalance = new BigNumber(String(bw.reservation?.MaxAmountU64 ?? bw.amount));
+      // Recover the coin type from the withdrawal's TypeTag so that re-building uses the exact
+      // coin type the transaction was created (and signed) with. Without this, buildSuiTransaction
+      // would re-derive the coin type from this._coinConfig, which is the parent chain config
+      // (no packageId/module/symbol) when the builder is constructed via the chain — producing an
+      // `undefined::undefined::undefined` coin type and a signature that fails on-chain verification.
+      const withdrawalTypeTag = bw?.typeArg?.Balance;
+      if (withdrawalTypeTag) {
+        // BCS decodes the struct address without the `0x` prefix; normalize it so the recovered
+        // coin type matches the config-derived form (`0x<addr>::module::name`). The serialized
+        // bytes are identical either way since parseFromStr re-normalizes the address on encode.
+        const [address, ...rest] = TypeTagSerializer.tagToString(withdrawalTypeTag).split('::');
+        this._tokenCoinTypeOverride = [normalizeSuiAddress(address), ...rest].join('::');
+      }
     }
 
     if (txData.inputObjects && txData.inputObjects.length > 0) {
diff --git a/modules/sdk-coin-sui/test/unit/transactionBuilder/tokenTransferBuilder.ts b/modules/sdk-coin-sui/test/unit/transactionBuilder/tokenTransferBuilder.ts
index d79e0702a4..0eca2828c7 100644
--- a/modules/sdk-coin-sui/test/unit/transactionBuilder/tokenTransferBuilder.ts
+++ b/modules/sdk-coin-sui/test/unit/transactionBuilder/tokenTransferBuilder.ts
@@ -180,6 +180,32 @@ describe('Sui Token Transfer Builder', () => {
       rebuiltTx.toBroadcastFormat().should.equal(rawTx);
     });
 
+    it('should preserve the token coin type when rebuilt with the parent chain config', async function () {
+      // Reproduces the production broadcast path: the transaction is created with the token config
+      // (tsui:deep) but re-assembled for broadcast by a builder constructed with the parent CHAIN
+      // config (tsui, no packageId/module/symbol). Before the fix, buildSuiTransaction re-derived
+      // the coin type from the chain config and produced `undefined::undefined::undefined`, changing
+      // the tx bytes so the already-computed signature failed on-chain verification.
+      const txBuilder = factory.getTokenTransferBuilder();
+      txBuilder.type(SuiTransactionType.TokenTransfer);
+      txBuilder.sender(testData.sender.address);
+      txBuilder.send([{ address: testData.recipients[0].address, amount: '1000' }]);
+      txBuilder.gasData(testData.gasData);
+      txBuilder.fundsInAddressBalance(FUNDS_IN_ADDRESS_BALANCE);
+      const rawTx = (await txBuilder.build()).toBroadcastFormat();
+      // Rebuild using the CHAIN config, not the token config.
+      const chainFactory = getBuilderFactory('tsui');
+      const rebuilder = chainFactory.from(rawTx);
+      rebuilder.addSignature({ pub: testData.sender.publicKey }, Buffer.from(testData.sender.signatureHex));
+      const rebuiltTx = await rebuilder.build();
+      // Bytes must be unchanged so the signature still verifies.
+      rebuiltTx.toBroadcastFormat().should.equal(rawTx);
+      const rebuiltProgrammableTx = (rebuiltTx as SuiTransaction<TokenTransferProgrammableTransaction>).suiTransaction
+        .tx;
+      (rebuiltProgrammableTx.transactions[0] as any).target.should.equal('0x2::coin::redeem_funds');
+      (rebuiltProgrammableTx.transactions[0] as any).typeArguments[0].should.equal(TOKEN_COIN_TYPE);
+    });
+
     it('should build a token transfer with coin objects + address balance', async function () {
       const numberOfInputObjects = 3;
       const inputObjects = testData.generateObjects(numberOfInputObjects);