fix(client-utils): harden native fee metadata and address review feedback

Keep wei decimals on network fees, skip chainlist testnet slip44:1,
restore guarded POL alias, mock chainlist in unit tests, cover inbound
STANDARD synthesis, and trim eth-chainlist typings.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: n3ps

packages/client-utils/src/mappers/api-transaction-mapper.test.ts

@@ -1006,6 +1006,28 @@ describe('mapApiTransaction', () => {
     });
   });
 
+  it('maps a STANDARD receive with empty valueTransfers to a native receive', () => {
+    const item = mapApiTransaction(
+      apiTransactionFixtures.mapArgs.mapsAStandardInboundWithoutTransfers,
+    );
+
+    expect(item).toMatchObject({
+      type: 'receive',
+      chainId: 'eip155:1',
+      data: {
+        to: subjectAddress,
+        token: {
+          direction: 'in',
+          amount: '1000000000000000000',
+          decimals: 18,
+          symbol: 'ETH',
+          assetType: 'native',
+          assetId: 'eip155:1/slip44:60',
+        },
+      },
+    });
+  });
+
   it('maps an Across USDT exchange with no native valueTransfers to a swap with native fees', () => {
     const item = mapApiTransaction(
       apiTransactionFixtures.mapArgs.mapsAnAcrossUsdtExchangeWithNativeFee,

packages/client-utils/src/mappers/api-transaction-mapper.ts

@@ -224,7 +224,9 @@ export function mapApiTransaction({
         const nativeAsset = getNativeAsset(chainId);
         if (nativeAsset) {
           token = {
-            ...nativeAsset,
+            symbol: nativeAsset.symbol,
+            decimals: nativeAsset.decimals,
+            assetId: nativeAsset.assetId,
             amount: transaction.value,
             direction,
             assetType: 'native',

packages/client-utils/src/mappers/constants.ts

@@ -32,6 +32,8 @@ export const tokenTransferLogTopicHash =
 
 export const nativeTokenAddress = '0x0000000000000000000000000000000000000000';
 
+export const nativeTokenDecimals = 18;
+
 export const swapsWrappedTokensAddresses = {
   '0x1': '0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2',
   '0x539': '0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2',

packages/client-utils/src/mappers/helpers/caip.test.ts

@@ -8,17 +8,14 @@ import {
 } from './caip.js';
 
 jest.mock('eth-chainlist', () => ({
-  ...jest.requireActual('eth-chainlist'),
   getChainById: jest.fn(),
 }));
 
 const mockGetChainById = jest.mocked(getChainById);
 
 describe('caip helpers', () => {
   beforeEach(() => {
-    mockGetChainById.mockImplementation(
-      jest.requireActual('eth-chainlist').getChainById,
-    );
+    mockGetChainById.mockReset();
   });
 
   describe('formatChainIdToCaip', () => {
@@ -131,15 +128,24 @@ describe('caip helpers', () => {
   });
 
   describe('getNativeAsset', () => {
-    it('resolves mainnet native asset from chainlist slip44', () => {
+    it('resolves native asset from chainlist slip44', () => {
+      mockGetChainById.mockReturnValue({
+        slip44: 60,
+        nativeCurrency: { name: 'Ether', symbol: 'ETH', decimals: 18 },
+      } as ReturnType<typeof getChainById>);
+
       expect(getNativeAsset('eip155:1')).toStrictEqual({
         symbol: 'ETH',
         decimals: 18,
         assetId: 'eip155:1/slip44:60',
       });
     });
 
-    it('resolves arbitrum native asset via symbol fallback when chainlist omits slip44', () => {
+    it('falls back to symbol lookup when chainlist omits slip44', () => {
+      mockGetChainById.mockReturnValue({
+        nativeCurrency: { name: 'Ether', symbol: 'ETH', decimals: 18 },
+      } as ReturnType<typeof getChainById>);
+
       expect(getNativeAsset('eip155:42161')).toStrictEqual({
         symbol: 'ETH',
         decimals: 18,
@@ -148,6 +154,11 @@ describe('caip helpers', () => {
     });
 
     it('ignores chainlist testnet slip44:1 and uses the native symbol coin type', () => {
+      mockGetChainById.mockReturnValue({
+        slip44: 1,
+        nativeCurrency: { name: 'Ether', symbol: 'ETH', decimals: 18 },
+      } as ReturnType<typeof getChainById>);
+
       expect(getNativeAsset('eip155:11155111')).toStrictEqual({
         symbol: 'ETH',
         decimals: 18,
@@ -156,21 +167,29 @@ describe('caip helpers', () => {
     });
 
     it('prefers chainlist slip44 over the slip44 registry symbol mapping', () => {
+      mockGetChainById.mockReturnValue({
+        slip44: 9005,
+        nativeCurrency: { name: 'Avalanche', symbol: 'AVAX', decimals: 18 },
+      } as ReturnType<typeof getChainById>);
+
       expect(getNativeAsset('eip155:43114')).toStrictEqual({
         symbol: 'AVAX',
         decimals: 18,
         assetId: 'eip155:43114/slip44:9005',
       });
     });
 
-    it('returns undefined for unknown chains', () => {
+    it('returns undefined when the chain is unknown', () => {
+      mockGetChainById.mockReturnValue(undefined);
+
       expect(getNativeAsset('eip155:999999991')).toBeUndefined();
     });
 
     it('returns undefined for non-eip155 chain ids', () => {
       expect(
         getNativeAsset('solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp'),
       ).toBeUndefined();
+      expect(mockGetChainById).not.toHaveBeenCalled();
     });
 
     it('returns undefined when chainlist omits native currency symbol', () => {
@@ -182,7 +201,28 @@ describe('caip helpers', () => {
       expect(getNativeAsset('eip155:1')).toBeUndefined();
     });
 
+    it('defaults decimals when chainlist omits native currency decimals', () => {
+      mockGetChainById.mockReturnValue({
+        slip44: 60,
+        nativeCurrency: { name: 'Ether', symbol: 'ETH' },
+      } as ReturnType<typeof getChainById>);
+
+      expect(getNativeAsset('eip155:1')).toStrictEqual({
+        symbol: 'ETH',
+        decimals: 18,
+        assetId: 'eip155:1/slip44:60',
+      });
+    });
+
     it('returns undefined when slip44 and symbol lookup both fail', () => {
+      mockGetChainById.mockReturnValue({
+        nativeCurrency: {
+          name: 'Unknown',
+          symbol: 'NOTACOIN',
+          decimals: 18,
+        },
+      } as ReturnType<typeof getChainById>);
+
       expect(getNativeAsset('eip155:1088')).toBeUndefined();
     });
   });

packages/client-utils/src/mappers/helpers/caip.ts

@@ -11,7 +11,7 @@ import {
 } from '@metamask/utils';
 import { getChainById } from 'eth-chainlist';
 
-import { nativeTokenAddress } from '../constants.js';
+import { nativeTokenAddress, nativeTokenDecimals } from '../constants.js';
 
 const slip44BySymbol = ((): Map<string, string> => {
   const coinTypeBySymbol = new Map<string, string>();
@@ -26,7 +26,10 @@ const slip44BySymbol = ((): Map<string, string> => {
     }
   }
 
-  coinTypeBySymbol.set('POL', coinTypeBySymbol.get('MATIC') as string);
+  const maticCoinType = coinTypeBySymbol.get('MATIC');
+  if (maticCoinType && !coinTypeBySymbol.has('POL')) {
+    coinTypeBySymbol.set('POL', maticCoinType);
+  }
 
   return coinTypeBySymbol;
 })();
@@ -91,6 +94,14 @@ export function resolveNativeAssetId(
   return toCaipAssetType(namespace, reference, 'slip44', assetReference);
 }
 
+/**
+ * Resolves EVM native symbol, decimals, and slip44 asset id for a chain.
+ * Prefers eth-chainlist slip44 except testnet coin type 1, then falls back to
+ * `@metamask/slip44` by native symbol.
+ *
+ * @param chainId - CAIP-2 chain id (eip155 only).
+ * @returns Native asset metadata, or undefined when it cannot be resolved.
+ */
 export function getNativeAsset(chainId: CaipChainId):
   | {
       symbol: string;
@@ -125,7 +136,7 @@ export function getNativeAsset(chainId: CaipChainId):
 
   return {
     symbol: nativeCurrency.symbol,
-    decimals: nativeCurrency.decimals,
+    decimals: nativeCurrency.decimals ?? nativeTokenDecimals,
     assetId: toCaipAssetType(namespace, reference, 'slip44', assetReference),
   };
 }

packages/client-utils/src/mappers/helpers/transactions.test.ts

@@ -252,7 +252,8 @@ describe('transaction helpers', () => {
   });
 
   describe('getLocalTransactionFees', () => {
-    it('resolves native fee metadata from chain id when nativeAssetSymbol is omitted', () => {
+    it('resolves fee assetId via ETH symbol when chainlist only has testnet slip44:1', () => {
+      // 0x539 = Geth Testnet (1337); chainlist slip44 is 1, which we skip.
       expect(
         getLocalTransactionFees({
           primaryTransaction: {
@@ -326,6 +327,55 @@ describe('transaction helpers', () => {
         } as Parameters<typeof getLocalTransactionFees>[0]),
       ).toBeUndefined();
     });
+
+    it('resolves fee assetId from nativeAssetSymbol when the chain is unknown', () => {
+      expect(
+        getLocalTransactionFees({
+          nativeAssetSymbol: 'ETH',
+          primaryTransaction: {
+            chainId: '0x3b9ac9f7',
+            txParams: {},
+            txReceipt: {
+              gasUsed: '0x1',
+              effectiveGasPrice: '0x2',
+            },
+          },
+        } as Parameters<typeof getLocalTransactionFees>[0]),
+      ).toStrictEqual([
+        {
+          type: 'base',
+          amount: '2',
+          decimals: 18,
+          assetType: 'native',
+          symbol: 'ETH',
+          assetId: 'eip155:999999991/slip44:60',
+        },
+      ]);
+    });
+
+    it('keeps the nativeAssetSymbol on fees when it cannot be mapped to an assetId', () => {
+      expect(
+        getLocalTransactionFees({
+          nativeAssetSymbol: 'NOTACOIN',
+          primaryTransaction: {
+            chainId: '0x3b9ac9f7',
+            txParams: {},
+            txReceipt: {
+              gasUsed: '0x1',
+              effectiveGasPrice: '0x2',
+            },
+          },
+        } as Parameters<typeof getLocalTransactionFees>[0]),
+      ).toStrictEqual([
+        {
+          type: 'base',
+          amount: '2',
+          decimals: 18,
+          assetType: 'native',
+          symbol: 'NOTACOIN',
+        },
+      ]);
+    });
   });
 
   describe('getFees', () => {
@@ -443,6 +493,22 @@ describe('transaction helpers', () => {
         },
       ]);
     });
+
+    it('keeps wei decimals for fees when chainlist nativeCurrency.decimals is not 18', () => {
+      expect(
+        getFees({
+          chainId: 4160,
+          gasUsed: '21000',
+          effectiveGasPrice: '1000000000',
+        } as Parameters<typeof getFees>[0]),
+      ).toMatchObject({
+        0: {
+          amount: '21000000000000',
+          decimals: 18,
+          symbol: 'ALGO',
+        },
+      });
+    });
   });
 
   describe('getLocalTransactionStatus', () => {

packages/client-utils/src/mappers/helpers/transactions.ts

@@ -18,6 +18,7 @@ import type {
   TokenAmount,
   ValueTransfer,
 } from '../../types.js';
+import { nativeTokenDecimals } from '../constants.js';
 import {
   formatAddressToAssetId,
   formatChainIdToCaip,
@@ -36,8 +37,6 @@ export type TransactionGroup = {
   transactions: TransactionMeta[];
 };
 
-const nativeTokenDecimals = 18;
-
 function calculateNetworkFee(
   gasUsed: string | number | undefined,
   gasPrice: string | number | undefined,
@@ -64,16 +63,14 @@ function toNetworkFee(
     return {
       type: 'base',
       amount,
-      decimals: nativeAsset.decimals,
+      decimals: nativeTokenDecimals,
       assetType: 'native',
       symbol: symbol ?? nativeAsset.symbol,
       assetId: nativeAsset.assetId,
     };
   }
 
-  const assetId = symbol
-    ? resolveNativeAssetId(chainId, symbol)
-    : undefined;
+  const assetId = symbol ? resolveNativeAssetId(chainId, symbol) : undefined;
 
   return {
     type: 'base',

packages/client-utils/test/fixtures/api-transactions.ts

@@ -1044,6 +1044,19 @@ const transactions = {
     readable: 'Sent',
     readableExtended: 'Sent',
   },
+  mapsAStandardInboundWithoutTransfers: {
+    hash: '0xstandardinboundwithouttransfers',
+    timestamp: '2026-05-12T13:37:47.000Z',
+    chainId: 1,
+    from: '0x1111111111111111111111111111111111111111',
+    to: addresses.subjectAddress,
+    transactionCategory: 'STANDARD',
+    value: '1000000000000000000',
+    valueTransfers: [],
+    isError: false,
+    gasUsed: 21000,
+    effectiveGasPrice: '1',
+  },
   mapsAnAcrossUsdtExchangeWithNativeFee: {
     hash: '0x34bbaa01262f2e9221913316f4548a4b5981e05ee338ea586fc267a6868f9526',
     timestamp: '2026-07-28T10:29:49.000Z',
@@ -1243,6 +1256,10 @@ const mapArgs = {
     subjectAddress: addresses.subjectAddress,
     transaction: transactions.mapsAZeroValueStandardSendWithoutTransfers,
   },
+  mapsAStandardInboundWithoutTransfers: {
+    subjectAddress: addresses.subjectAddress,
+    transaction: transactions.mapsAStandardInboundWithoutTransfers,
+  },
   mapsAnAcrossUsdtExchangeWithNativeFee: {
     subjectAddress: addresses.subjectAddress,
     transaction: transactions.mapsAnAcrossUsdtExchangeWithNativeFee,

types/eth-chainlist.d.ts

@@ -5,23 +5,11 @@ declare module 'eth-chainlist' {
     networkId?: number;
     slip44?: number;
     nativeCurrency?: {
-      name: string;
-      symbol: string;
-      decimals: number;
+      name?: string;
+      symbol?: string;
+      decimals?: number;
     };
   };
 
   export function getChainById(chainId: number): ChainListEntry | undefined;
-
-  export function getChainByNetworkId(
-    networkId: number,
-  ): ChainListEntry | undefined;
-
-  export function getChainByName(name: string): ChainListEntry | undefined;
-
-  export function getChainByShortName(
-    shortName: string,
-  ): ChainListEntry | undefined;
-
-  export function rawChainData(): ChainListEntry[];
 }