feat: HTS NFT support

modules/abstract-eth/src/lib/transferBuilders/transferBuilderERC721.ts

@@ -4,7 +4,12 @@ import { hexlify, hexZeroPad } from 'ethers/lib/utils';
 import { ContractCall } from '../contractCall';
 import { decodeERC721TransferData, isValidEthAddress, sendMultiSigData } from '../utils';
 import { BaseNFTTransferBuilder } from './baseNFTTransferBuilder';
-import { ERC721SafeTransferTypeMethodId, ERC721SafeTransferTypes } from '../walletUtil';
+import {
+  ERC721SafeTransferTypeMethodId,
+  ERC721SafeTransferTypes,
+  ERC721TransferFromMethodId,
+  ERC721TransferFromTypes,
+} from '../walletUtil';
 import { coins, EthereumNetwork as EthLikeNetwork } from '@bitgo/statics';
 
 export class ERC721TransferBuilder extends BaseNFTTransferBuilder {
@@ -54,6 +59,17 @@ export class ERC721TransferBuilder extends BaseNFTTransferBuilder {
     return contractCall.serialize();
   }
 
+  /**
+   * Build using transferFrom(address,address,uint256) without the bytes data parameter.
+   * Required for HTS NFT transfers on Hedera EVM, which only supports transferFrom.
+   */
+  buildTransferFrom(): string {
+    const types = ERC721TransferFromTypes;
+    const values = [this._fromAddress, this._toAddress, this._tokenId];
+    const contractCall = new ContractCall(ERC721TransferFromMethodId, types, values);
+    return contractCall.serialize();
+  }
+
   signAndBuild(chainId: string): string {
     this._chainId = chainId;
     if (this.hasMandatoryFields()) {

modules/abstract-eth/src/lib/utils.ts

@@ -51,6 +51,8 @@ import {
   ERC1155SafeTransferTypes,
   ERC721SafeTransferTypeMethodId,
   ERC721SafeTransferTypes,
+  ERC721TransferFromMethodId,
+  ERC721TransferFromTypes,
   flushCoinsMethodId,
   flushCoinsTypes,
   flushForwarderTokensMethodId,
@@ -509,26 +511,46 @@ export function decodeERC721TransferData(data: string): ERC721TransferData {
   );
 
   const internalDataHex = bufferToHex(internalData as Buffer);
-  if (!internalDataHex.startsWith(ERC721SafeTransferTypeMethodId)) {
-    throw new BuildTransactionError(`Invalid transfer bytecode: ${data}`);
+
+  if (internalDataHex.startsWith(ERC721SafeTransferTypeMethodId)) {
+    const [from, receiver, tokenId, userSentData] = getRawDecoded(
+      ERC721SafeTransferTypes,
+      getBufferedByteCode(ERC721SafeTransferTypeMethodId, internalDataHex)
+    );
+
+    return {
+      to: addHexPrefix(receiver as string),
+      from: addHexPrefix(from as string),
+      expireTime: bufferToInt(expireTime as Buffer),
+      amount: new BigNumber(bufferToHex(amount as Buffer)).toFixed(),
+      tokenId: new BigNumber(bufferToHex(tokenId as Buffer)).toFixed(),
+      sequenceId: bufferToInt(sequenceId as Buffer),
+      signature: bufferToHex(signature as Buffer),
+      tokenContractAddress: addHexPrefix(to as string),
+      userData: bufferToHex(userSentData as Buffer),
+    };
   }
 
-  const [from, receiver, tokenId, userSentData] = getRawDecoded(
-    ERC721SafeTransferTypes,
-    getBufferedByteCode(ERC721SafeTransferTypeMethodId, internalDataHex)
-  );
+  if (internalDataHex.startsWith(ERC721TransferFromMethodId)) {
+    const [from, receiver, tokenId] = getRawDecoded(
+      ERC721TransferFromTypes,
+      getBufferedByteCode(ERC721TransferFromMethodId, internalDataHex)
+    );
 
-  return {
-    to: addHexPrefix(receiver as string),
-    from: addHexPrefix(from as string),
-    expireTime: bufferToInt(expireTime as Buffer),
-    amount: new BigNumber(bufferToHex(amount as Buffer)).toFixed(),
-    tokenId: new BigNumber(bufferToHex(tokenId as Buffer)).toFixed(),
-    sequenceId: bufferToInt(sequenceId as Buffer),
-    signature: bufferToHex(signature as Buffer),
-    tokenContractAddress: addHexPrefix(to as string),
-    userData: bufferToHex(userSentData as Buffer),
-  };
+    return {
+      to: addHexPrefix(receiver as string),
+      from: addHexPrefix(from as string),
+      expireTime: bufferToInt(expireTime as Buffer),
+      amount: new BigNumber(bufferToHex(amount as Buffer)).toFixed(),
+      tokenId: new BigNumber(bufferToHex(tokenId as Buffer)).toFixed(),
+      sequenceId: bufferToInt(sequenceId as Buffer),
+      signature: bufferToHex(signature as Buffer),
+      tokenContractAddress: addHexPrefix(to as string),
+      userData: '',
+    };
+  }
+
+  throw new BuildTransactionError(`Invalid transfer bytecode: ${data}`);
 }
 
 export function decodeERC1155TransferData(data: string): ERC1155TransferData {

modules/abstract-eth/src/lib/walletUtil.ts

@@ -16,6 +16,7 @@ export const flushERC1155ForwarderTokensMethodId = '0xe6bd0aa4';
 export const flushERC1155ForwarderTokensMethodIdV4 = '0x8972c17c';
 
 export const ERC721SafeTransferTypeMethodId = '0xb88d4fde';
+export const ERC721TransferFromMethodId = '0x23b872dd';
 export const ERC1155SafeTransferTypeMethodId = '0xf242432a';
 export const ERC1155BatchTransferTypeMethodId = '0x2eb2c2d6';
 export const defaultForwarderVersion = 0;
@@ -38,6 +39,7 @@ export const sendMultiSigTokenTypes = ['address', 'uint', 'address', 'uint', 'ui
 export const sendMultiSigTokenTypesFirstSigner = ['string', 'address', 'uint', 'address', 'uint', 'uint'];
 
 export const ERC721SafeTransferTypes = ['address', 'address', 'uint256', 'bytes'];
+export const ERC721TransferFromTypes = ['address', 'address', 'uint256'];
 
 export const ERC1155SafeTransferTypes = ['address', 'address', 'uint256', 'uint256', 'bytes'];
 export const ERC1155BatchTransferTypes = ['address', 'address', 'uint256[]', 'uint256[]', 'bytes'];

modules/abstract-eth/test/unit/utils.ts

@@ -5,6 +5,8 @@ import {
   decodeFlushERC721TokensData,
   decodeFlushERC1155TokensData,
 } from '../../src/lib/utils';
+import { ERC721TransferBuilder } from '../../src/lib/transferBuilders/transferBuilderERC721';
+import { ERC721TransferFromMethodId, ERC721SafeTransferTypeMethodId } from '../../src/lib/walletUtil';
 
 describe('Abstract ETH Utils', () => {
   describe('ERC721 Flush Functions', () => {
@@ -209,6 +211,44 @@ describe('Abstract ETH Utils', () => {
     });
   });
 
+  describe('ERC721TransferBuilder.buildTransferFrom', () => {
+    const owner = '0x19645032c7f1533395d44a629462e751084d3e4d';
+    const recipient = '0x19645032c7f1533395d44a629462e751084d3e4c';
+    const htsNftAddress = '0x00000000000000000000000000000000007ac203';
+
+    it('should encode transferFrom with selector 0x23b872dd', () => {
+      const builder = new ERC721TransferBuilder();
+      builder.tokenContractAddress(htsNftAddress).to(recipient).from(owner).tokenId('12');
+
+      const data = builder.buildTransferFrom();
+
+      should.exist(data);
+      data.should.startWith(ERC721TransferFromMethodId); // 0x23b872dd
+    });
+
+    it('should encode safeTransferFrom with selector 0xb88d4fde via build()', () => {
+      const builder = new ERC721TransferBuilder();
+      builder.tokenContractAddress(htsNftAddress).to(recipient).from(owner).tokenId('12');
+
+      const data = builder.build();
+
+      should.exist(data);
+      data.should.startWith(ERC721SafeTransferTypeMethodId); // 0xb88d4fde
+    });
+
+    it('should produce different encodings for build() vs buildTransferFrom()', () => {
+      const builder = new ERC721TransferBuilder();
+      builder.tokenContractAddress(htsNftAddress).to(recipient).from(owner).tokenId('12');
+
+      const safeTransferData = builder.build();
+      const transferFromData = builder.buildTransferFrom();
+
+      safeTransferData.should.not.equal(transferFromData);
+      // transferFrom encoding should be shorter (no bytes param)
+      transferFromData.length.should.be.lessThan(safeTransferData.length);
+    });
+  });
+
   describe('Token Address Validation', () => {
     it('should preserve address format in encoding/decoding', () => {
       const forwarderAddress = '0x8f977e912ef500548a0c3be6ddde9899f1199b81';

modules/sdk-coin-eth/test/unit/transactionBuilder/sendNFT.ts

@@ -266,6 +266,60 @@ describe('Eth transaction builder sendNFT', () => {
   });
 });
 
+// ABI for transferFrom(address,address,uint256) used by HTS native NFTs on Hedera EVM
+const transferFromABI = [
+  {
+    inputs: [
+      { internalType: 'address', name: 'from', type: 'address' },
+      { internalType: 'address', name: 'to', type: 'address' },
+      { internalType: 'uint256', name: 'tokenId', type: 'uint256' },
+    ],
+    name: 'transferFrom',
+    outputs: [],
+    stateMutability: 'nonpayable',
+    type: 'function',
+  },
+];
+
+describe('ERC721 HTS native NFT transferFrom', () => {
+  const owner = '0x19645032c7f1533395d44a629462e751084d3e4d';
+  const recipient = '0x19645032c7f1533395d44a629462e751084d3e4c';
+  // HTS native NFT address (long-zero format)
+  const htsNftContractAddress = '0x00000000000000000000000000000000007ac203';
+  const tokenId = '12';
+
+  it('should build ERC721 transferFrom calldata with correct selector and params', () => {
+    const builder = new ERC721TransferBuilder();
+    builder.tokenContractAddress(htsNftContractAddress).to(recipient).from(owner).tokenId(tokenId);
+
+    const calldata = builder.buildTransferFrom();
+
+    // Should use transferFrom selector 0x23b872dd
+    calldata.should.startWith('0x23b872dd');
+
+    // Decode and verify parameters
+    const decoded = decodeTransaction(JSON.stringify(transferFromABI), calldata);
+    should.equal(decoded.args[0].toLowerCase(), owner.toLowerCase());
+    should.equal(decoded.args[1].toLowerCase(), recipient.toLowerCase());
+    should.equal(decoded.args[2].toString(), tokenId);
+  });
+
+  it('should not include bytes data parameter in transferFrom calldata', () => {
+    const builder = new ERC721TransferBuilder();
+    builder.tokenContractAddress(htsNftContractAddress).to(recipient).from(owner).tokenId(tokenId);
+
+    const transferFromData = builder.buildTransferFrom();
+    const safeTransferData = builder.build();
+
+    // transferFrom has 3 params (from, to, tokenId), safeTransferFrom has 4 (+ bytes data)
+    // So transferFrom encoding should be shorter
+    transferFromData.length.should.be.lessThan(safeTransferData.length);
+
+    // Verify safeTransferFrom uses 0xb88d4fde
+    safeTransferData.should.startWith('0xb88d4fde');
+  });
+});
+
 function decodeTransaction(abi: string, calldata: string) {
   const contractInterface = new ethers.utils.Interface(abi);
   return contractInterface.parseTransaction({ data: calldata });

modules/sdk-coin-evm/src/evmCoin.ts

@@ -1,10 +1,19 @@
 /**
  * @prettier
  */
-import { BaseCoin, BitGoBase, common, MPCAlgorithm, MultisigType, multisigTypes } from '@bitgo/sdk-core';
+import {
+  BaseCoin,
+  BitGoBase,
+  BuildNftTransferDataOptions,
+  common,
+  MPCAlgorithm,
+  MultisigType,
+  multisigTypes,
+} from '@bitgo/sdk-core';
 import { BaseCoin as StaticsBaseCoin, CoinFeature, coins, CoinFamily } from '@bitgo/statics';
 import {
   AbstractEthLikeNewCoins,
+  ERC721TransferBuilder,
   OfflineVaultTxInfo,
   RecoverOptions,
   recoveryBlockchainExplorerQuery,
@@ -13,7 +22,7 @@ import {
   VerifyEthTransactionOptions,
 } from '@bitgo/abstract-eth';
 import { TransactionBuilder } from './lib';
-import { recovery_HBAREVM_BlockchainExplorerQuery, validateHederaAccountId } from './lib/utils';
+import { isHtsEvmAddress, recovery_HBAREVM_BlockchainExplorerQuery, validateHederaAccountId } from './lib/utils';
 import assert from 'assert';
 
 export class EvmCoin extends AbstractEthLikeNewCoins {
@@ -135,4 +144,17 @@ export class EvmCoin extends AbstractEthLikeNewCoins {
     }
     return super.isValidAddress(address);
   }
+
+  /** @inheritDoc */
+  buildNftTransferData(params: BuildNftTransferDataOptions): string {
+    if (params.type === 'ERC721' && isHtsEvmAddress(params.tokenContractAddress)) {
+      return new ERC721TransferBuilder()
+        .tokenContractAddress(params.tokenContractAddress)
+        .to(params.recipientAddress)
+        .from(params.fromAddress)
+        .tokenId(params.tokenId)
+        .buildTransferFrom();
+    }
+    return super.buildNftTransferData(params);
+  }
 }

modules/sdk-coin-evm/src/lib/utils.ts

@@ -224,6 +224,18 @@ async function getGasLimitFromRPC(query: Record<string, string>, rpcUrl: string)
   return response.body;
 }
 
+/**
+ * Check if an EVM address is an HTS (Hedera Token Service) native address.
+ * HTS entities on Hedera EVM use "long-zero" addresses where the first 12 bytes are all zeros
+ * and the entity number occupies the last 8 bytes (e.g. 0x00000000000000000000000000000000007ac203).
+ * Standard Solidity contracts have normal EVM addresses derived from public key hashes.
+ */
+export function isHtsEvmAddress(address: string): boolean {
+  const normalized = address.toLowerCase();
+  // First 12 bytes (24 hex chars) after '0x' prefix are all zeros
+  return /^0x0{24}[0-9a-f]{16}$/.test(normalized);
+}
+
 export function validateHederaAccountId(address: string): { valid: boolean; error: string | null } {
   const parts = address.split('.');
   if (parts.length !== 3) {

modules/sdk-coin-evm/test/unit/utils.ts

@@ -1,9 +1,35 @@
 import nock from 'nock';
 import 'should';
 
-import { recovery_HBAREVM_BlockchainExplorerQuery } from '../../src/lib/utils';
+import { isHtsEvmAddress, recovery_HBAREVM_BlockchainExplorerQuery } from '../../src/lib/utils';
 
 describe('EVM Coin Utils', function () {
+  describe('isHtsEvmAddress', () => {
+    it('should return true for HTS native token addresses (long-zero format)', () => {
+      isHtsEvmAddress('0x00000000000000000000000000000000007ac203').should.be.true();
+      isHtsEvmAddress('0x00000000000000000000000000000000007103a5').should.be.true();
+      isHtsEvmAddress('0x0000000000000000000000000000000000728a62').should.be.true();
+      isHtsEvmAddress('0x00000000000000000000000000000000007ac19c').should.be.true();
+    });
+
+    it('should return false for standard Solidity contract addresses', () => {
+      isHtsEvmAddress('0x5df4076613e714a4cc4284abac87caa927b918a8').should.be.false();
+      isHtsEvmAddress('0xcee79325714727016c125f80ef1a5d1f47b3d8d2').should.be.false();
+      isHtsEvmAddress('0xc795c4faae7f16a69bec13c5dfd9e8a156a68625').should.be.false();
+      isHtsEvmAddress('0x8f977e912ef500548a0c3be6ddde9899f1199b81').should.be.false();
+    });
+
+    it('should handle uppercase hex characters', () => {
+      isHtsEvmAddress('0x00000000000000000000000000000000007AC203').should.be.true();
+      isHtsEvmAddress('0x5DF4076613E714A4CC4284ABAC87CAA927B918A8').should.be.false();
+    });
+
+    it('should return false for invalid format', () => {
+      isHtsEvmAddress('0x1234').should.be.false();
+      isHtsEvmAddress('not-an-address').should.be.false();
+    });
+  });
+
   describe('recovery_HBAREVM_BlockchainExplorerQuery', function () {
     const mockRpcUrl = 'https://testnet.hashio.io/api';
     const mockExplorerUrl = 'https://testnet.mirrornode.hedera.com/api/v1';