feat: Implement FiatStrategy submit flow with order polling and relay execution

packages/transaction-pay-controller/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Implement fiat strategy submit flow with order polling and relay execution ([#8347](https://github.com/MetaMask/core/pull/8347))
+
 ## [19.0.3]
 
 ### Changed

packages/transaction-pay-controller/src/TransactionPayController.test.ts

@@ -7,18 +7,21 @@ import { TransactionPayController } from '.';
 import { updateFiatPayment } from './actions/update-fiat-payment';
 import { updatePaymentToken } from './actions/update-payment-token';
 import { TransactionPayStrategy } from './constants';
+import { deriveFiatAssetForFiatPayment } from './strategy/fiat/utils';
 import { getMessengerMock } from './tests/messenger-mock';
 import type {
   TransactionPayControllerMessenger,
   TransactionPaySourceAmount,
+  UpdateTransactionDataCallback,
 } from './types';
 import { getStrategyOrder } from './utils/feature-flags';
 import { updateQuotes } from './utils/quotes';
 import { updateSourceAmounts } from './utils/source-amounts';
-import { pollTransactionChanges } from './utils/transaction';
+import { getTransaction, pollTransactionChanges } from './utils/transaction';
 
 jest.mock('./actions/update-fiat-payment');
 jest.mock('./actions/update-payment-token');
+jest.mock('./strategy/fiat/utils');
 jest.mock('./utils/source-amounts');
 jest.mock('./utils/quotes');
 jest.mock('./utils/transaction');
@@ -32,6 +35,10 @@ const CHAIN_ID_MOCK = '0x1' as Hex;
 describe('TransactionPayController', () => {
   const updateFiatPaymentMock = jest.mocked(updateFiatPayment);
   const updatePaymentTokenMock = jest.mocked(updatePaymentToken);
+  const deriveFiatAssetForFiatPaymentMock = jest.mocked(
+    deriveFiatAssetForFiatPayment,
+  );
+  const getTransactionMock = jest.mocked(getTransaction);
   const updateSourceAmountsMock = jest.mocked(updateSourceAmounts);
   const updateQuotesMock = jest.mocked(updateQuotes);
   const pollTransactionChangesMock = jest.mocked(pollTransactionChanges);
@@ -503,4 +510,129 @@ describe('TransactionPayController', () => {
       ).toBeUndefined();
     });
   });
+
+  describe('fiat token selection', () => {
+    const CAIP_ASSET_ID_MOCK = 'eip155:137/slip44:966';
+    const FIAT_ASSET_MOCK = {
+      address: '0x0000000000000000000000000000000000001010' as Hex,
+      caipAssetId: CAIP_ASSET_ID_MOCK,
+      chainId: '0x89' as Hex,
+      decimals: 18,
+    };
+
+    let setSelectedTokenMock: jest.Mock;
+
+    beforeEach(() => {
+      setSelectedTokenMock = jest.fn();
+      messenger.registerActionHandler(
+        'RampsController:setSelectedToken' as never,
+        setSelectedTokenMock as never,
+      );
+    });
+
+    function getUpdateTransactionData(): UpdateTransactionDataCallback {
+      const controller = createController();
+      controller.updatePaymentToken({
+        transactionId: TRANSACTION_ID_MOCK,
+        tokenAddress: TOKEN_ADDRESS_MOCK,
+        chainId: CHAIN_ID_MOCK,
+      });
+      return updatePaymentTokenMock.mock.calls[0][1].updateTransactionData;
+    }
+
+    it('does not call setSelectedToken when only fiat amount changes', () => {
+      getTransactionMock.mockReturnValue(TRANSACTION_META_MOCK);
+      deriveFiatAssetForFiatPaymentMock.mockReturnValue(FIAT_ASSET_MOCK);
+
+      const updateTransactionData = getUpdateTransactionData();
+
+      updateTransactionData(TRANSACTION_ID_MOCK, (data) => {
+        data.fiatPayment = { amountFiat: '100' };
+      });
+
+      expect(setSelectedTokenMock).not.toHaveBeenCalled();
+    });
+
+    it('calls RampsController:setSelectedToken when payment method changes', () => {
+      getTransactionMock.mockReturnValue(TRANSACTION_META_MOCK);
+      deriveFiatAssetForFiatPaymentMock.mockReturnValue(FIAT_ASSET_MOCK);
+
+      const updateTransactionData = getUpdateTransactionData();
+
+      updateTransactionData(TRANSACTION_ID_MOCK, (data) => {
+        data.fiatPayment = { selectedPaymentMethodId: 'card-123' };
+      });
+
+      expect(setSelectedTokenMock).toHaveBeenCalledWith(CAIP_ASSET_ID_MOCK);
+    });
+
+    it('triggers quote update when fiat payment changes', () => {
+      getTransactionMock.mockReturnValue(TRANSACTION_META_MOCK);
+      deriveFiatAssetForFiatPaymentMock.mockReturnValue(FIAT_ASSET_MOCK);
+
+      const updateTransactionData = getUpdateTransactionData();
+
+      updateTransactionData(TRANSACTION_ID_MOCK, (data) => {
+        data.fiatPayment = { amountFiat: '100' };
+      });
+
+      expect(updateQuotesMock).toHaveBeenCalledTimes(1);
+    });
+
+    it('does not call setSelectedToken when transaction is not found', () => {
+      getTransactionMock.mockReturnValue(undefined);
+
+      const updateTransactionData = getUpdateTransactionData();
+
+      updateTransactionData(TRANSACTION_ID_MOCK, (data) => {
+        data.fiatPayment = { selectedPaymentMethodId: 'card-123' };
+      });
+
+      expect(setSelectedTokenMock).not.toHaveBeenCalled();
+    });
+
+    it('does not call setSelectedToken when fiat asset cannot be derived', () => {
+      getTransactionMock.mockReturnValue(TRANSACTION_META_MOCK);
+      deriveFiatAssetForFiatPaymentMock.mockReturnValue(undefined);
+
+      const updateTransactionData = getUpdateTransactionData();
+
+      updateTransactionData(TRANSACTION_ID_MOCK, (data) => {
+        data.fiatPayment = { selectedPaymentMethodId: 'card-123' };
+      });
+
+      expect(setSelectedTokenMock).not.toHaveBeenCalled();
+    });
+
+    it('does not call setSelectedToken when fiat payment does not change', () => {
+      getTransactionMock.mockReturnValue(TRANSACTION_META_MOCK);
+      deriveFiatAssetForFiatPaymentMock.mockReturnValue(FIAT_ASSET_MOCK);
+
+      const updateTransactionData = getUpdateTransactionData();
+
+      updateTransactionData(TRANSACTION_ID_MOCK, (data) => {
+        data.sourceAmounts = [
+          { sourceAmountHuman: '1.23' } as TransactionPaySourceAmount,
+        ];
+      });
+
+      expect(setSelectedTokenMock).not.toHaveBeenCalled();
+    });
+
+    it('does not throw when setSelectedToken throws', () => {
+      getTransactionMock.mockReturnValue(TRANSACTION_META_MOCK);
+      deriveFiatAssetForFiatPaymentMock.mockReturnValue(FIAT_ASSET_MOCK);
+      setSelectedTokenMock.mockImplementation(() => {
+        throw new Error('Tokens not loaded');
+      });
+
+      const updateTransactionData = getUpdateTransactionData();
+
+      expect(() => {
+        updateTransactionData(TRANSACTION_ID_MOCK, (data) => {
+          data.fiatPayment = { selectedPaymentMethodId: 'card-123' };
+        });
+      }).not.toThrow();
+    });
+  });
 });

packages/transaction-pay-controller/src/TransactionPayController.ts

@@ -12,6 +12,7 @@ import {
   TransactionPayStrategy,
 } from './constants';
 import { QuoteRefresher } from './helpers/QuoteRefresher';
+import { deriveFiatAssetForFiatPayment } from './strategy/fiat/utils';
 import type {
   GetDelegationTransactionCallback,
   TransactionConfigCallback,
@@ -25,7 +26,7 @@ import type {
 import { getStrategyOrder } from './utils/feature-flags';
 import { updateQuotes } from './utils/quotes';
 import { updateSourceAmounts } from './utils/source-amounts';
-import { pollTransactionChanges } from './utils/transaction';
+import { getTransaction, pollTransactionChanges } from './utils/transaction';
 
 const MESSENGER_EXPOSED_METHODS = [
   'getDelegationTransaction',
@@ -207,6 +208,7 @@ export class TransactionPayController extends BaseController<
     fn: (transactionData: Draft<TransactionData>) => void,
   ): void {
     let shouldUpdateQuotes = false;
+    let shouldUpdateFiatToken = false;
 
     this.update((state) => {
       const { transactionData } = state;
@@ -215,6 +217,9 @@ export class TransactionPayController extends BaseController<
       const originalTokens = current?.tokens;
       const originalIsMaxAmount = current?.isMaxAmount;
       const originalIsPostQuote = current?.isPostQuote;
+      const originalFiatPaymentAmount = current?.fiatPayment?.amountFiat;
+      const originalFiatPaymentMethodId =
+        current?.fiatPayment?.selectedPaymentMethodId;
 
       if (!current) {
         transactionData[transactionId] = {
@@ -236,6 +241,11 @@ export class TransactionPayController extends BaseController<
       const isTokensUpdated = current.tokens !== originalTokens;
       const isIsMaxUpdated = current.isMaxAmount !== originalIsMaxAmount;
       const isPostQuoteUpdated = current.isPostQuote !== originalIsPostQuote;
+      const isFiatAmountUpdated =
+        current.fiatPayment?.amountFiat !== originalFiatPaymentAmount;
+      const isFiatPaymentMethodUpdated =
+        current.fiatPayment?.selectedPaymentMethodId !==
+        originalFiatPaymentMethodId;
 
       if (
         isPaymentTokenUpdated ||
@@ -247,8 +257,34 @@ export class TransactionPayController extends BaseController<
 
         shouldUpdateQuotes = true;
       }
+
+      if (isFiatAmountUpdated || isFiatPaymentMethodUpdated) {
+        shouldUpdateQuotes = true;
+      }
+
+      if (isFiatPaymentMethodUpdated) {
+        shouldUpdateFiatToken = true;
+      }
     });
 
+    if (shouldUpdateFiatToken) {
+      const transaction = getTransaction(
+        transactionId,
+        this.messenger,
+      ) as TransactionMeta;
+      const fiatAsset = deriveFiatAssetForFiatPayment(transaction);
+      if (fiatAsset) {
+        try {
+          this.messenger.call(
+            'RampsController:setSelectedToken',
+            fiatAsset.caipAssetId,
+          );
+        } catch {
+          // Intentionally no-op — tokens may not be loaded in RampsController yet.
+        }
+      }
+    }
+
     if (shouldUpdateQuotes) {
       updateQuotes({
         getStrategies: this.#getStrategiesWithFallback.bind(this),