fix(statics): add EIP1559 to ETH_FEATURES_WITH_FRANKFURT for v4 forwarder flush

ETH mainnet has required EIP1559 (type-2) transactions since the London
hard fork (Aug 2021). Tokens on Ethereum using ETH_FEATURES_WITH_FRANKFURT
(e.g. SUSHI, LINK, DAI) lacked the EIP1559 coin feature flag, which caused
the BitGo platform to fall back to legacy transaction format when building
flush transactions for v4 forwarders. V4 forwarders require the flush
transaction to be sent directly to the forwarder address using the
flushTokens(address) method — and this path requires EIP1559 on mainnet.

Add CoinFeature.EIP1559 to ETH_FEATURES_WITH_FRANKFURT so all tokens using
this feature set (including SUSHI) correctly declare EIP1559 support and
receive properly-typed flush transactions from v4 hot wallet forwarders.

Also add a regression test that builds a SUSHI v4 forwarder flush with
EIP1559 fees, confirming the correct method ID and calldata encoding.

Ticket: COINS-558
Session-Id: 11a8d890-1ca4-4c30-acd7-158927258cfd
Task-Id: d32e686b-2479-4535-a80d-0b0ee0871065

Author: Support Bot

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

@@ -162,6 +162,41 @@ describe('Eth Transaction builder flush tokens (ETH-specific)', function () {
       txJson.data.should.startWith(flushForwarderTokensMethodIdV4);
     });
 
+    it('a SUSHI token flush from v4 forwarder with EIP-1559 fees', async () => {
+      // SUSHI mainnet contract: 0x6b3595068778dd592e39a122f4f5a5cf09c90fe2
+      // For v4 forwarder, contractAddress must equal forwarderAddress
+      const sushiContractAddress = '0x6b3595068778dd592e39a122f4f5a5cf09c90fe2';
+      const v4ForwarderAddress = '0x53b8e91bb3b8f618b5f01004ef108f134f219573';
+
+      const tx = await buildTransaction({
+        fee: {
+          fee: '30',
+          eip1559: {
+            maxPriorityFeePerGas: '2000000000',
+            maxFeePerGas: '30000000000',
+          },
+          gasLimit: '100000',
+        },
+        counter: 1,
+        forwarderAddress: v4ForwarderAddress,
+        tokenAddress: sushiContractAddress,
+        contractAddress: v4ForwarderAddress,
+        forwarderVersion: 4,
+      });
+
+      tx.type.should.equal(TransactionType.FlushTokens);
+      const txJson = tx.toJson();
+      txJson.gasLimit.should.equal('100000');
+      txJson._type.should.equals(ETHTransactionType.EIP1559);
+      txJson.maxFeePerGas!.should.equal('30000000000');
+      txJson.maxPriorityFeePerGas!.should.equal('2000000000');
+      txJson.to!.should.equal(v4ForwarderAddress);
+      should.equal(txJson.nonce, 1);
+      txJson.data.should.startWith(flushForwarderTokensMethodIdV4);
+      // Verify SUSHI contract address is encoded in calldata
+      txJson.data.should.containEql(sushiContractAddress.slice(2).toLowerCase());
+    });
+
     it('decode wallet flush forwarder transaction with forwarder Version 4', async () => {
       const tx = await buildTransaction({
         fee: {

modules/statics/src/coinFeatures.ts

@@ -702,7 +702,11 @@ export const POLYX_TOKEN_FEATURES = [
   CoinFeature.TOKEN_STANDARD_USES_ALTERNATIVE_ADDRESS_IDENTIFIER,
 ];
 
-export const ETH_FEATURES_WITH_FRANKFURT = [...ETH_FEATURES, CoinFeature.CUSTODY_BITGO_FRANKFURT];
+export const ETH_FEATURES_WITH_FRANKFURT = [
+  ...ETH_FEATURES,
+  CoinFeature.CUSTODY_BITGO_FRANKFURT,
+  CoinFeature.EIP1559,
+];
 export const ETH_FEATURES_WITH_GERMANY = [...ETH_FEATURES, CoinFeature.CUSTODY_BITGO_GERMANY];
 export const ETH_FEATURES_WITH_FRANKFURT_GERMANY = [...ETH_FEATURES_WITH_FRANKFURT, CoinFeature.CUSTODY_BITGO_GERMANY];
 export const SOL_TOKEN_FEATURES_WITH_FRANKFURT = [

modules/statics/test/unit/coins.ts

@@ -1288,6 +1288,7 @@ describe('Eip1559 coins', () => {
     'toas',
     'coredao',
     'tcoredao',
+    'sushi',
   ];
   it('should have EIP1559 feature', () => {
     eip1559Coins.forEach((coinName) => {