From 7a2e679a098d5c0d9de117432ffb80b10843870d Mon Sep 17 00:00:00 2001
From: Micaela Estabillo <micaela.estabillo@consensys.net>
Date: Mon, 22 Sep 2025 11:07:16 -0700
Subject: [PATCH 1/8] wip

---
 .../app/wallet-overview/coin-buttons.tsx      |  9 ++-
 ui/ducks/bridge/selectors.ts                  | 69 ++++++++++++++++++-
 ui/hooks/bridge/useBridgeQueryParams.ts       |  3 +
 ui/hooks/bridge/useBridging.ts                | 48 ++++++++++---
 4 files changed, 113 insertions(+), 16 deletions(-)

diff --git a/ui/components/app/wallet-overview/coin-buttons.tsx b/ui/components/app/wallet-overview/coin-buttons.tsx
index fa06b3646f7d..d2c36c7af685 100644
--- a/ui/components/app/wallet-overview/coin-buttons.tsx
+++ b/ui/components/app/wallet-overview/coin-buttons.tsx
@@ -9,7 +9,7 @@ import { getNativeAssetForChainId } from '@metamask/bridge-controller';
 import { isEvmAccountType } from '@metamask/keyring-api';
 import { InternalAccount } from '@metamask/keyring-internal-api';
 ///: END:ONLY_INCLUDE_IF
-import { ChainId } from '../../../../shared/constants/network';
+import { CHAIN_IDS, ChainId } from '../../../../shared/constants/network';
 
 import { I18nContext } from '../../../contexts/i18n';
 
@@ -328,11 +328,14 @@ const CoinButtons = ({
 
   const handleBridgeOnClick = useCallback(
     async (isSwap: boolean) => {
-      await setCorrectChain();
       // Handle clicking from the wallet overview page
       openBridgeExperience(
         MetaMetricsSwapsEventSource.MainView,
-        getNativeAssetForChainId(chainId),
+        // TODO sync this with token filter or selectedChainId
+        getNativeAssetForChainId(
+          location.pathname.split('/').filter(Boolean).at(-1) ??
+            CHAIN_IDS.MAINNET,
+        ),
         isSwap,
       );
     },
diff --git a/ui/ducks/bridge/selectors.ts b/ui/ducks/bridge/selectors.ts
index c7efac2622d2..b82c12bd59af 100644
--- a/ui/ducks/bridge/selectors.ts
+++ b/ui/ducks/bridge/selectors.ts
@@ -24,7 +24,12 @@ import { createSelector } from 'reselect';
 import type { GasFeeState } from '@metamask/gas-fee-controller';
 import { BigNumber } from 'bignumber.js';
 import { calcTokenAmount } from '@metamask/notification-services-controller/push-services';
-import type { CaipAssetType, CaipChainId, Hex } from '@metamask/utils';
+import {
+  parseCaipChainId,
+  type CaipAssetType,
+  type CaipChainId,
+  type Hex,
+} from '@metamask/utils';
 import type {
   CurrencyRateState,
   MultichainAssetsControllerState,
@@ -182,9 +187,13 @@ export const getFromChains = createDeepEqualSelector(
 );
 
 export const getFromChain = createDeepEqualSelector(
-  getMultichainProviderConfig,
+  getMultichainProviderConfig, // TODO remove this reference
+  // TODO should be based on fromToken
   getFromChains,
   (providerConfig, fromChains) => {
+    // TODO move this to bridge state?
+    // TODO return null initially, wait for token selection then set to token's chainId
+    // otherwise should use EVM
     return fromChains.find(({ chainId }) => chainId === providerConfig.chainId);
   },
 );
@@ -228,6 +237,60 @@ export const getToChain = createSelector(
       : fromChain,
 );
 
+export const getDefaultTokenPair = createDeepEqualSelector(
+  [
+    (state) => getFromChain(state)?.chainId,
+    (state) =>
+      // @ts-expect-error will be fixed when controller is updated
+      getBridgeFeatureFlags(state).bip44DefaultPairs,
+    // TODO remove fallback and update LD to this
+    // ({
+    //   bip122: {
+    //     other: {},
+    //     standard: {
+    //       'bip122:000000000019d6689c085ae165831e93/slip44:0':
+    //         'eip155:1/slip44:60',
+    //     },
+    //   },
+    //   eip155: {
+    //     other: {},
+    //     standard: {
+    //       'eip155:1/slip44:60':
+    //         // 'eip155:1/erc20:0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48',
+    //         'eip155:1/erc20:0x1f9840a85d5aF5bf1D1762F925BDADdC4201F984',
+    //     },
+    //   },
+    //   solana: {
+    //     other: {},
+    //     standard: {
+    //       'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp/slip44:501':
+    //         'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp/token:EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v',
+    //     },
+    //   },
+    // }),
+  ],
+  (fromChainId, bip44DefaultPairs): null | [CaipAssetType, CaipAssetType] => {
+    console.log('=====getDefaultTokenPair', fromChainId);
+    if (!fromChainId) {
+      return null;
+    }
+    const { namespace } = parseCaipChainId(formatChainIdToCaip(fromChainId));
+    // console.log(
+    //   '=====getDefaultTokenPair namespace',
+    //   namespace,
+    //   bip44DefaultPairs,
+    // );
+    const defaultTokenPair = bip44DefaultPairs[namespace].standard;
+    if (defaultTokenPair) {
+      return Object.entries(defaultTokenPair).flat() as [
+        CaipAssetType,
+        CaipAssetType,
+      ];
+    }
+    return null;
+  },
+);
+
 export const getFromToken = createSelector(
   [(state: BridgeAppState) => state.bridge.fromToken, getFromChain],
   (fromToken, fromChain) => {
@@ -260,6 +323,8 @@ export const getToToken = createSelector(
     if (toToken) {
       return toToken;
     }
+    console.log('=====returning hardcoded toToken');
+    // TODO if fromToken is in bip44Defaults, return its mapped toToken
     // Otherwise, determine the default token to use based on fromToken and toChain
     const defaultToken = getDefaultToToken(toChain, fromToken);
     return defaultToken ? toBridgeToken(defaultToken) : null;
diff --git a/ui/hooks/bridge/useBridgeQueryParams.ts b/ui/hooks/bridge/useBridgeQueryParams.ts
index 8d8c8d75ae7e..17ded85579ac 100644
--- a/ui/hooks/bridge/useBridgeQueryParams.ts
+++ b/ui/hooks/bridge/useBridgeQueryParams.ts
@@ -150,6 +150,7 @@ export const useBridgeQueryParams = () => {
       if (searchParamsTo?.assetId || searchParamsFrom?.assetId) {
         abortController.current.abort();
         abortController.current = new AbortController();
+        console.log('=====fetching asset metadata');
         fetchAssetMetadata(
           abortController.current.signal,
           searchParamsFrom?.assetId,
@@ -173,6 +174,7 @@ export const useBridgeQueryParams = () => {
       const { chainId: fromChainId } = fromAsset;
 
       if (fromTokenMetadata) {
+        console.log('=====setting fromToken', fromTokenMetadata.symbol);
         const { chainId, assetReference } = parseCaipAssetType(
           fromTokenMetadata.assetId,
         );
@@ -214,6 +216,7 @@ export const useBridgeQueryParams = () => {
       const { chainId, assetReference } = parseCaipAssetType(
         toTokenMetadata.assetId,
       );
+      console.log('=====setting toToken', toTokenMetadata.symbol);
       dispatch(
         setToToken({
           ...toTokenMetadata,
diff --git a/ui/hooks/bridge/useBridging.ts b/ui/hooks/bridge/useBridging.ts
index 101d21f66814..c8fe45547e7a 100644
--- a/ui/hooks/bridge/useBridging.ts
+++ b/ui/hooks/bridge/useBridging.ts
@@ -34,6 +34,7 @@ import { trace, TraceName } from '../../../shared/lib/trace';
 import { toAssetId } from '../../../shared/lib/asset-utils';
 import { ALLOWED_BRIDGE_CHAIN_IDS_IN_CAIP } from '../../../shared/constants/bridge';
 import { getMultichainProviderConfig } from '../../selectors/multichain';
+import { getDefaultTokenPair } from '../../ducks/bridge/selectors';
 
 const useBridging = () => {
   const history = useHistory();
@@ -49,6 +50,10 @@ const useBridging = () => {
   const isBridgeChain = useSelector((state) =>
     getIsBridgeChain(state, providerConfig?.chainId),
   );
+
+  // TODO should set default toToken here too
+  const defaultTokenPair = useSelector(getDefaultTokenPair);
+
   const openBridgeExperience = useCallback(
     (
       location: MetaMetricsSwapsEventSource | 'Carousel',
@@ -57,19 +62,30 @@ const useBridging = () => {
       },
       isSwap = false,
     ) => {
-      const token =
-        srcToken ?? getNativeAssetForChainId(providerConfig.chainId);
+      console.log('=====useBridging', defaultTokenPair);
+      // TODO if no network filter, default to ethereum
+      // TODO if no srcToken, get default
+      const token = srcToken;
+
       const isBridgeToken =
         token?.chainId &&
         ALLOWED_BRIDGE_CHAIN_IDS_IN_CAIP.includes(
           formatChainIdToCaip(token.chainId),
         );
-      const isChainOrTokenSupported = isBridgeChain || isBridgeToken;
+
+      const isChainOrTokenSupported =
+        isBridgeChain || isBridgeToken || defaultTokenPair;
 
       if (!isChainOrTokenSupported || !providerConfig) {
         return;
       }
 
+      // TODO if srcToken is defined, use getDefaultToToken
+      // const defaultToken = getDefaultToToken(token.chainId, fromToken);
+      // const defaultDestToken ? toBridgeToken(defaultToken) : null;
+
+      const [defaultSrcAssetId, defaultDestAssetId] = defaultTokenPair ?? [];
+
       trace({
         name: isSwap ? TraceName.SwapViewLoaded : TraceName.BridgeViewLoaded,
         startTime: Date.now(),
@@ -82,7 +98,7 @@ const useBridging = () => {
         properties: {
           // TODO: Fix in https://github.com/MetaMask/metamask-extension/issues/31860
           // eslint-disable-next-line @typescript-eslint/naming-convention
-          token_symbol: token.symbol,
+          token_symbol: token?.symbol ?? defaultSrcAssetId ?? '',
           location,
           text: isSwap ? 'Swap' : 'Bridge',
           // TODO: Fix in https://github.com/MetaMask/metamask-extension/issues/31860
@@ -95,19 +111,28 @@ const useBridging = () => {
           location: location as never,
           // TODO: Fix in https://github.com/MetaMask/metamask-extension/issues/31860
           // eslint-disable-next-line @typescript-eslint/naming-convention
-          token_symbol_source: token.symbol,
+          token_symbol_source: token?.symbol ?? defaultSrcAssetId ?? '',
           // TODO: Fix in https://github.com/MetaMask/metamask-extension/issues/31860
           // eslint-disable-next-line @typescript-eslint/naming-convention
-          token_symbol_destination: null,
+          token_symbol_destination: defaultDestAssetId ?? '',
         }),
       );
       dispatch(resetInputFields());
       let url = `${CROSS_CHAIN_SWAP_ROUTE}${PREPARE_SWAP_ROUTE}`;
-      const assetId = toAssetId(
-        token.address,
-        formatChainIdToCaip(token.chainId ?? providerConfig.chainId),
-      );
-      url += `?${BridgeQueryParams.FROM}=${assetId}`;
+      const assetId =
+        (token
+          ? toAssetId(
+              token.address,
+              formatChainIdToCaip(token.chainId ?? providerConfig.chainId),
+            )
+          : defaultSrcAssetId) ??
+        getNativeAssetForChainId(providerConfig.chainId)?.assetId;
+      if (assetId) {
+        url += `?${BridgeQueryParams.FROM}=${assetId}`;
+      }
+      if (defaultDestAssetId && !srcToken) {
+        url += `&${BridgeQueryParams.TO}=${defaultDestAssetId}`;
+      }
       if (isSwap) {
         url += `&${BridgeQueryParams.SWAPS}=true`;
       }
@@ -121,6 +146,7 @@ const useBridging = () => {
       isMetaMetricsEnabled,
       isMarketingEnabled,
       providerConfig,
+      defaultTokenPair,
     ],
   );
 

From 172fea618b92aabe76e41c4da9815efb605bf236 Mon Sep 17 00:00:00 2001
From: Micaela Estabillo <micaela.estabillo@consensys.net>
Date: Mon, 22 Sep 2025 11:43:12 -0700
Subject: [PATCH 2/8] refactor: useBridging

---
 ui/hooks/bridge/useBridging.ts | 52 ++++++++++++++++++----------------
 1 file changed, 27 insertions(+), 25 deletions(-)

diff --git a/ui/hooks/bridge/useBridging.ts b/ui/hooks/bridge/useBridging.ts
index c8fe45547e7a..63bdd84c467e 100644
--- a/ui/hooks/bridge/useBridging.ts
+++ b/ui/hooks/bridge/useBridging.ts
@@ -35,6 +35,7 @@ import { toAssetId } from '../../../shared/lib/asset-utils';
 import { ALLOWED_BRIDGE_CHAIN_IDS_IN_CAIP } from '../../../shared/constants/bridge';
 import { getMultichainProviderConfig } from '../../selectors/multichain';
 import { getDefaultTokenPair } from '../../ducks/bridge/selectors';
+import { getDefaultToToken } from '../../ducks/bridge/utils';
 
 const useBridging = () => {
   const history = useHistory();
@@ -65,27 +66,36 @@ const useBridging = () => {
       console.log('=====useBridging', defaultTokenPair);
       // TODO if no network filter, default to ethereum
       // TODO if no srcToken, get default
-      const token = srcToken;
+      const [defaultBip44SrcAssetId, defaultBip44DestAssetId] =
+        defaultTokenPair ?? [];
+      const srcAssetIdToUse =
+        (srcToken
+          ? toAssetId(
+              srcToken.address,
+              formatChainIdToCaip(srcToken.chainId ?? providerConfig.chainId),
+            )
+          : defaultBip44SrcAssetId) ??
+        getNativeAssetForChainId(providerConfig.chainId)?.assetId;
+      // TODO use hardcoded dest token if srcToken is defined
+      const destAssetIdToUse = srcToken ? null : defaultBip44DestAssetId;
+
+      // TODO if srcToken is defined, use getDefaultToToken
+      // const defaultToken = srcToken? getDefaultToToken(srcToken.chainId, srcToken) : getDefaultToToken(providerConfig.chainId, fromToken);
+      // const defaultDestToken ? toBridgeToken(defaultToken) : null;
 
       const isBridgeToken =
-        token?.chainId &&
+        srcToken?.chainId &&
         ALLOWED_BRIDGE_CHAIN_IDS_IN_CAIP.includes(
-          formatChainIdToCaip(token.chainId),
+          formatChainIdToCaip(srcToken.chainId),
         );
 
       const isChainOrTokenSupported =
-        isBridgeChain || isBridgeToken || defaultTokenPair;
+        isBridgeChain || isBridgeToken || srcAssetIdToUse;
 
       if (!isChainOrTokenSupported || !providerConfig) {
         return;
       }
 
-      // TODO if srcToken is defined, use getDefaultToToken
-      // const defaultToken = getDefaultToToken(token.chainId, fromToken);
-      // const defaultDestToken ? toBridgeToken(defaultToken) : null;
-
-      const [defaultSrcAssetId, defaultDestAssetId] = defaultTokenPair ?? [];
-
       trace({
         name: isSwap ? TraceName.SwapViewLoaded : TraceName.BridgeViewLoaded,
         startTime: Date.now(),
@@ -98,7 +108,7 @@ const useBridging = () => {
         properties: {
           // TODO: Fix in https://github.com/MetaMask/metamask-extension/issues/31860
           // eslint-disable-next-line @typescript-eslint/naming-convention
-          token_symbol: token?.symbol ?? defaultSrcAssetId ?? '',
+          token_symbol: srcToken?.symbol ?? defaultBip44SrcAssetId ?? '',
           location,
           text: isSwap ? 'Swap' : 'Bridge',
           // TODO: Fix in https://github.com/MetaMask/metamask-extension/issues/31860
@@ -111,27 +121,19 @@ const useBridging = () => {
           location: location as never,
           // TODO: Fix in https://github.com/MetaMask/metamask-extension/issues/31860
           // eslint-disable-next-line @typescript-eslint/naming-convention
-          token_symbol_source: token?.symbol ?? defaultSrcAssetId ?? '',
+          token_symbol_source: srcToken?.symbol ?? defaultBip44SrcAssetId ?? '',
           // TODO: Fix in https://github.com/MetaMask/metamask-extension/issues/31860
           // eslint-disable-next-line @typescript-eslint/naming-convention
-          token_symbol_destination: defaultDestAssetId ?? '',
+          token_symbol_destination: destAssetIdToUse ?? '',
         }),
       );
       dispatch(resetInputFields());
       let url = `${CROSS_CHAIN_SWAP_ROUTE}${PREPARE_SWAP_ROUTE}`;
-      const assetId =
-        (token
-          ? toAssetId(
-              token.address,
-              formatChainIdToCaip(token.chainId ?? providerConfig.chainId),
-            )
-          : defaultSrcAssetId) ??
-        getNativeAssetForChainId(providerConfig.chainId)?.assetId;
-      if (assetId) {
-        url += `?${BridgeQueryParams.FROM}=${assetId}`;
+      if (srcAssetIdToUse) {
+        url += `?${BridgeQueryParams.FROM}=${srcAssetIdToUse}`;
       }
-      if (defaultDestAssetId && !srcToken) {
-        url += `&${BridgeQueryParams.TO}=${defaultDestAssetId}`;
+      if (destAssetIdToUse) {
+        url += `&${BridgeQueryParams.TO}=${destAssetIdToUse}`;
       }
       if (isSwap) {
         url += `&${BridgeQueryParams.SWAPS}=true`;

From ae67e76067d62ed17467434f51e0eacb767f4923 Mon Sep 17 00:00:00 2001
From: Micaela Estabillo <micaela.estabillo@consensys.net>
Date: Mon, 22 Sep 2025 11:58:25 -0700
Subject: [PATCH 3/8] fix: if srcToken is present, add default toToken to URL

---
 shared/constants/bridge.ts     | 22 +++++++++++-----------
 ui/ducks/bridge/selectors.ts   |  5 ++++-
 ui/ducks/bridge/utils.ts       | 11 ++++-------
 ui/hooks/bridge/useBridging.ts | 17 +++++++----------
 4 files changed, 26 insertions(+), 29 deletions(-)

diff --git a/shared/constants/bridge.ts b/shared/constants/bridge.ts
index 376787d2c0ed..bd1344ec5d82 100644
--- a/shared/constants/bridge.ts
+++ b/shared/constants/bridge.ts
@@ -88,7 +88,7 @@ export const STATIC_METAMASK_BASE_URL = 'https://static.cx.metamask.io';
 
 export const BRIDGE_CHAINID_COMMON_TOKEN_PAIR: Partial<
   Record<
-    AllowedBridgeChainIds,
+    (typeof ALLOWED_BRIDGE_CHAIN_IDS_IN_CAIP)[number],
     {
       address: string;
       symbol: string;
@@ -97,70 +97,70 @@ export const BRIDGE_CHAINID_COMMON_TOKEN_PAIR: Partial<
     }
   >
 > = {
-  [CHAIN_IDS.MAINNET]: {
+  [toEvmCaipChainId(CHAIN_IDS.MAINNET)]: {
     // ETH -> USDC on mainnet
     address: '0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48',
     symbol: 'USDC',
     decimals: 6,
     name: 'USD Coin',
   },
-  [CHAIN_IDS.OPTIMISM]: {
+  [toEvmCaipChainId(CHAIN_IDS.OPTIMISM)]: {
     // ETH -> USDC on Optimism
     address: '0x0b2c639c533813f4aa9d7837caf62653d097ff85',
     symbol: 'USDC',
     decimals: 6,
     name: 'USD Coin',
   },
-  [CHAIN_IDS.ARBITRUM]: {
+  [toEvmCaipChainId(CHAIN_IDS.ARBITRUM)]: {
     // ETH -> USDC on Arbitrum
     address: '0xaf88d065e77c8cc2239327c5edb3a432268e5831',
     symbol: 'USDC',
     decimals: 6,
     name: 'USD Coin',
   },
-  [CHAIN_IDS.BASE]: {
+  [toEvmCaipChainId(CHAIN_IDS.BASE)]: {
     // ETH -> USDC on Base
     address: '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913',
     symbol: 'USDC',
     decimals: 6,
     name: 'USD Coin',
   },
-  [CHAIN_IDS.POLYGON]: {
+  [toEvmCaipChainId(CHAIN_IDS.POLYGON)]: {
     // POL -> USDT on Polygon
     address: '0xc2132d05d31c914a87c6611c10748aeb04b58e8f',
     symbol: 'USDT',
     decimals: 6,
     name: 'Tether USD',
   },
-  [CHAIN_IDS.BSC]: {
+  [toEvmCaipChainId(CHAIN_IDS.BSC)]: {
     // BNB -> USDT on BSC
     address: '0x55d398326f99059ff775485246999027b3197955',
     symbol: 'USDT',
     decimals: 18,
     name: 'Tether USD',
   },
-  [CHAIN_IDS.AVALANCHE]: {
+  [toEvmCaipChainId(CHAIN_IDS.AVALANCHE)]: {
     // AVAX -> USDC on Avalanche
     address: '0xb97ef9ef8734c71904d8002f8b6bc66dd9c48a6e',
     symbol: 'USDC',
     decimals: 6,
     name: 'USD Coin',
   },
-  [CHAIN_IDS.ZKSYNC_ERA]: {
+  [toEvmCaipChainId(CHAIN_IDS.ZKSYNC_ERA)]: {
     // ETH -> USDT on zkSync Era
     address: '0x493257fd37edb34451f62edf8d2a0c418852ba4c',
     symbol: 'USDT',
     decimals: 6,
     name: 'Tether USD',
   },
-  [CHAIN_IDS.LINEA_MAINNET]: {
+  [toEvmCaipChainId(CHAIN_IDS.LINEA_MAINNET)]: {
     // ETH -> USDC on Linea
     address: '0x176211869ca2b568f2a7d4ee941e073a821ee1ff',
     symbol: 'USDC',
     decimals: 6,
     name: 'USD Coin',
   },
-  [CHAIN_IDS.SEI]: {
+  [toEvmCaipChainId(CHAIN_IDS.SEI)]: {
     // SEI -> USDC on Sei
     address: '0x3894085Ef7Ff0f0aeDf52E2A2704928d1Ec074F1',
     symbol: 'USDC',
diff --git a/ui/ducks/bridge/selectors.ts b/ui/ducks/bridge/selectors.ts
index b82c12bd59af..4ce4b8b543a1 100644
--- a/ui/ducks/bridge/selectors.ts
+++ b/ui/ducks/bridge/selectors.ts
@@ -326,7 +326,10 @@ export const getToToken = createSelector(
     console.log('=====returning hardcoded toToken');
     // TODO if fromToken is in bip44Defaults, return its mapped toToken
     // Otherwise, determine the default token to use based on fromToken and toChain
-    const defaultToken = getDefaultToToken(toChain, fromToken);
+    const defaultToken = getDefaultToToken(
+      formatChainIdToCaip(toChain.chainId),
+      fromToken,
+    );
     return defaultToken ? toBridgeToken(defaultToken) : null;
   },
 );
diff --git a/ui/ducks/bridge/utils.ts b/ui/ducks/bridge/utils.ts
index cdebc063129e..1e7ea3a69b6f 100644
--- a/ui/ducks/bridge/utils.ts
+++ b/ui/ducks/bridge/utils.ts
@@ -266,7 +266,7 @@ const createBridgeTokenPayload = (
     name?: string;
     assetId?: string;
   },
-  chainId: ChainId | Hex,
+  chainId: ChainId | Hex | CaipChainId,
 ): TokenPayload['payload'] | null => {
   const { assetId, ...rest } = tokenData;
   return toBridgeToken({
@@ -276,13 +276,10 @@ const createBridgeTokenPayload = (
 };
 
 export const getDefaultToToken = (
-  { chainId: targetChainId }: NetworkConfiguration | AddNetworkFields,
-  fromToken: NonNullable<TokenPayload['payload']>,
+  targetChainId: CaipChainId,
+  fromToken: Pick<NonNullable<TokenPayload['payload']>, 'address'>,
 ) => {
-  const commonPair =
-    BRIDGE_CHAINID_COMMON_TOKEN_PAIR[
-      targetChainId as keyof typeof BRIDGE_CHAINID_COMMON_TOKEN_PAIR
-    ];
+  const commonPair = BRIDGE_CHAINID_COMMON_TOKEN_PAIR[targetChainId];
 
   if (commonPair) {
     // If source is native token, default to USDC on same chain
diff --git a/ui/hooks/bridge/useBridging.ts b/ui/hooks/bridge/useBridging.ts
index 63bdd84c467e..43273f16772c 100644
--- a/ui/hooks/bridge/useBridging.ts
+++ b/ui/hooks/bridge/useBridging.ts
@@ -35,7 +35,7 @@ import { toAssetId } from '../../../shared/lib/asset-utils';
 import { ALLOWED_BRIDGE_CHAIN_IDS_IN_CAIP } from '../../../shared/constants/bridge';
 import { getMultichainProviderConfig } from '../../selectors/multichain';
 import { getDefaultTokenPair } from '../../ducks/bridge/selectors';
-import { getDefaultToToken } from '../../ducks/bridge/utils';
+import { getDefaultToToken, toBridgeToken } from '../../ducks/bridge/utils';
 
 const useBridging = () => {
   const history = useHistory();
@@ -63,9 +63,6 @@ const useBridging = () => {
       },
       isSwap = false,
     ) => {
-      console.log('=====useBridging', defaultTokenPair);
-      // TODO if no network filter, default to ethereum
-      // TODO if no srcToken, get default
       const [defaultBip44SrcAssetId, defaultBip44DestAssetId] =
         defaultTokenPair ?? [];
       const srcAssetIdToUse =
@@ -76,12 +73,12 @@ const useBridging = () => {
             )
           : defaultBip44SrcAssetId) ??
         getNativeAssetForChainId(providerConfig.chainId)?.assetId;
-      // TODO use hardcoded dest token if srcToken is defined
-      const destAssetIdToUse = srcToken ? null : defaultBip44DestAssetId;
-
-      // TODO if srcToken is defined, use getDefaultToToken
-      // const defaultToken = srcToken? getDefaultToToken(srcToken.chainId, srcToken) : getDefaultToToken(providerConfig.chainId, fromToken);
-      // const defaultDestToken ? toBridgeToken(defaultToken) : null;
+      // If srcToken is present, use the default dest token for that chain
+      const destAssetIdToUse = srcToken?.chainId
+        ? toBridgeToken(
+            getDefaultToToken(formatChainIdToCaip(srcToken.chainId), srcToken),
+          )?.assetId
+        : defaultBip44DestAssetId;
 
       const isBridgeToken =
         srcToken?.chainId &&

From 97db74a4b507b73cdea1a351863dccbe0c07262d Mon Sep 17 00:00:00 2001
From: Micaela Estabillo <micaela.estabillo@consensys.net>
Date: Mon, 22 Sep 2025 13:05:51 -0700
Subject: [PATCH 4/8] chore: add comments

---
 ui/ducks/bridge/selectors.ts   |  1 -
 ui/hooks/bridge/useBridging.ts | 13 ++++++++++---
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/ui/ducks/bridge/selectors.ts b/ui/ducks/bridge/selectors.ts
index 4ce4b8b543a1..1416d6f898cd 100644
--- a/ui/ducks/bridge/selectors.ts
+++ b/ui/ducks/bridge/selectors.ts
@@ -323,7 +323,6 @@ export const getToToken = createSelector(
     if (toToken) {
       return toToken;
     }
-    console.log('=====returning hardcoded toToken');
     // TODO if fromToken is in bip44Defaults, return its mapped toToken
     // Otherwise, determine the default token to use based on fromToken and toChain
     const defaultToken = getDefaultToToken(
diff --git a/ui/hooks/bridge/useBridging.ts b/ui/hooks/bridge/useBridging.ts
index 43273f16772c..8104cbd9f3b3 100644
--- a/ui/hooks/bridge/useBridging.ts
+++ b/ui/hooks/bridge/useBridging.ts
@@ -32,6 +32,7 @@ import {
 import { BridgeQueryParams } from '../../../shared/lib/deep-links/routes/swap';
 import { trace, TraceName } from '../../../shared/lib/trace';
 import { toAssetId } from '../../../shared/lib/asset-utils';
+import { CHAIN_IDS } from '../../../shared/constants/network';
 import { ALLOWED_BRIDGE_CHAIN_IDS_IN_CAIP } from '../../../shared/constants/bridge';
 import { getMultichainProviderConfig } from '../../selectors/multichain';
 import { getDefaultTokenPair } from '../../ducks/bridge/selectors';
@@ -52,7 +53,6 @@ const useBridging = () => {
     getIsBridgeChain(state, providerConfig?.chainId),
   );
 
-  // TODO should set default toToken here too
   const defaultTokenPair = useSelector(getDefaultTokenPair);
 
   const openBridgeExperience = useCallback(
@@ -65,14 +65,21 @@ const useBridging = () => {
     ) => {
       const [defaultBip44SrcAssetId, defaultBip44DestAssetId] =
         defaultTokenPair ?? [];
+
       const srcAssetIdToUse =
+        // If srcToken is present, use the srcToken assetId
         (srcToken
           ? toAssetId(
               srcToken.address,
               formatChainIdToCaip(srcToken.chainId ?? providerConfig.chainId),
             )
-          : defaultBip44SrcAssetId) ??
-        getNativeAssetForChainId(providerConfig.chainId)?.assetId;
+          : // Otherwise, use the default bip44 src asset id
+            defaultBip44SrcAssetId) ??
+        // Otherwise, use the native asset for Ethereum mainnet
+        // This should only happen if the feature flags are unavailable and the
+        // user clicks on Swap from the home page
+        getNativeAssetForChainId(CHAIN_IDS.MAINNET)?.assetId;
+
       // If srcToken is present, use the default dest token for that chain
       const destAssetIdToUse = srcToken?.chainId
         ? toBridgeToken(

From 0c27a4d52283f78f0479afb6423cdca60eb18a33 Mon Sep 17 00:00:00 2001
From: Micaela Estabillo <micaela.estabillo@consensys.net>
Date: Mon, 22 Sep 2025 15:00:56 -0700
Subject: [PATCH 5/8] chore: remove comments and logs

---
 .../app/wallet-overview/coin-buttons.tsx      |  1 -
 ui/ducks/bridge/selectors.ts                  | 38 +------------------
 ui/hooks/bridge/useBridgeQueryParams.ts       |  3 --
 3 files changed, 1 insertion(+), 41 deletions(-)

diff --git a/ui/components/app/wallet-overview/coin-buttons.tsx b/ui/components/app/wallet-overview/coin-buttons.tsx
index d2c36c7af685..e19490e3f5ee 100644
--- a/ui/components/app/wallet-overview/coin-buttons.tsx
+++ b/ui/components/app/wallet-overview/coin-buttons.tsx
@@ -331,7 +331,6 @@ const CoinButtons = ({
       // Handle clicking from the wallet overview page
       openBridgeExperience(
         MetaMetricsSwapsEventSource.MainView,
-        // TODO sync this with token filter or selectedChainId
         getNativeAssetForChainId(
           location.pathname.split('/').filter(Boolean).at(-1) ??
             CHAIN_IDS.MAINNET,
diff --git a/ui/ducks/bridge/selectors.ts b/ui/ducks/bridge/selectors.ts
index 1416d6f898cd..b684995d9af1 100644
--- a/ui/ducks/bridge/selectors.ts
+++ b/ui/ducks/bridge/selectors.ts
@@ -187,13 +187,8 @@ export const getFromChains = createDeepEqualSelector(
 );
 
 export const getFromChain = createDeepEqualSelector(
-  getMultichainProviderConfig, // TODO remove this reference
-  // TODO should be based on fromToken
-  getFromChains,
+  [getMultichainProviderConfig, getFromChains],
   (providerConfig, fromChains) => {
-    // TODO move this to bridge state?
-    // TODO return null initially, wait for token selection then set to token's chainId
-    // otherwise should use EVM
     return fromChains.find(({ chainId }) => chainId === providerConfig.chainId);
   },
 );
@@ -243,43 +238,12 @@ export const getDefaultTokenPair = createDeepEqualSelector(
     (state) =>
       // @ts-expect-error will be fixed when controller is updated
       getBridgeFeatureFlags(state).bip44DefaultPairs,
-    // TODO remove fallback and update LD to this
-    // ({
-    //   bip122: {
-    //     other: {},
-    //     standard: {
-    //       'bip122:000000000019d6689c085ae165831e93/slip44:0':
-    //         'eip155:1/slip44:60',
-    //     },
-    //   },
-    //   eip155: {
-    //     other: {},
-    //     standard: {
-    //       'eip155:1/slip44:60':
-    //         // 'eip155:1/erc20:0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48',
-    //         'eip155:1/erc20:0x1f9840a85d5aF5bf1D1762F925BDADdC4201F984',
-    //     },
-    //   },
-    //   solana: {
-    //     other: {},
-    //     standard: {
-    //       'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp/slip44:501':
-    //         'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp/token:EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v',
-    //     },
-    //   },
-    // }),
   ],
   (fromChainId, bip44DefaultPairs): null | [CaipAssetType, CaipAssetType] => {
-    console.log('=====getDefaultTokenPair', fromChainId);
     if (!fromChainId) {
       return null;
     }
     const { namespace } = parseCaipChainId(formatChainIdToCaip(fromChainId));
-    // console.log(
-    //   '=====getDefaultTokenPair namespace',
-    //   namespace,
-    //   bip44DefaultPairs,
-    // );
     const defaultTokenPair = bip44DefaultPairs[namespace].standard;
     if (defaultTokenPair) {
       return Object.entries(defaultTokenPair).flat() as [
diff --git a/ui/hooks/bridge/useBridgeQueryParams.ts b/ui/hooks/bridge/useBridgeQueryParams.ts
index 17ded85579ac..8d8c8d75ae7e 100644
--- a/ui/hooks/bridge/useBridgeQueryParams.ts
+++ b/ui/hooks/bridge/useBridgeQueryParams.ts
@@ -150,7 +150,6 @@ export const useBridgeQueryParams = () => {
       if (searchParamsTo?.assetId || searchParamsFrom?.assetId) {
         abortController.current.abort();
         abortController.current = new AbortController();
-        console.log('=====fetching asset metadata');
         fetchAssetMetadata(
           abortController.current.signal,
           searchParamsFrom?.assetId,
@@ -174,7 +173,6 @@ export const useBridgeQueryParams = () => {
       const { chainId: fromChainId } = fromAsset;
 
       if (fromTokenMetadata) {
-        console.log('=====setting fromToken', fromTokenMetadata.symbol);
         const { chainId, assetReference } = parseCaipAssetType(
           fromTokenMetadata.assetId,
         );
@@ -216,7 +214,6 @@ export const useBridgeQueryParams = () => {
       const { chainId, assetReference } = parseCaipAssetType(
         toTokenMetadata.assetId,
       );
-      console.log('=====setting toToken', toTokenMetadata.symbol);
       dispatch(
         setToToken({
           ...toTokenMetadata,

From a1fe60a0072612d58781dc0603740f6c8444b2b0 Mon Sep 17 00:00:00 2001
From: Micaela Estabillo <micaela.estabillo@consensys.net>
Date: Tue, 23 Sep 2025 09:32:32 -0700
Subject: [PATCH 6/8] fix: tests

---
 ui/ducks/bridge/selectors.test.ts | 2 +-
 ui/ducks/bridge/selectors.ts      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/ui/ducks/bridge/selectors.test.ts b/ui/ducks/bridge/selectors.test.ts
index 8412ebd05ddf..e85ae134a20a 100644
--- a/ui/ducks/bridge/selectors.test.ts
+++ b/ui/ducks/bridge/selectors.test.ts
@@ -505,7 +505,7 @@ describe('Bridge selectors', () => {
         address: '0xaca92e438df0b2401ff60da7e4337b687a2435da',
         assetId: 'eip155:1/erc20:0xaca92e438df0b2401ff60da7e4337b687a2435da',
         balance: '0',
-        chainId: '0x1',
+        chainId: 'eip155:1',
         decimals: 18,
         image:
           'https://static.cx.metamask.io/api/v2/tokenIcons/assets/eip155/1/erc20/0xaca92e438df0b2401ff60da7e4337b687a2435da.png',
diff --git a/ui/ducks/bridge/selectors.ts b/ui/ducks/bridge/selectors.ts
index 32324854eb42..bec99ec94424 100644
--- a/ui/ducks/bridge/selectors.ts
+++ b/ui/ducks/bridge/selectors.ts
@@ -246,7 +246,7 @@ export const getDefaultTokenPair = createDeepEqualSelector(
       return null;
     }
     const { namespace } = parseCaipChainId(formatChainIdToCaip(fromChainId));
-    const defaultTokenPair = bip44DefaultPairs[namespace].standard;
+    const defaultTokenPair = bip44DefaultPairs?.[namespace]?.standard;
     if (defaultTokenPair) {
       return Object.entries(defaultTokenPair).flat() as [
         CaipAssetType,

From 0d5aa7339ee150c8a421589fdc539103a4cbd346 Mon Sep 17 00:00:00 2001
From: Micaela Estabillo <micaela.estabillo@consensys.net>
Date: Tue, 23 Sep 2025 10:14:01 -0700
Subject: [PATCH 7/8] test: add useBridging unit test

---
 ui/hooks/bridge/useBridging.test.ts | 97 ++++++++++++++++++++++++++++-
 1 file changed, 94 insertions(+), 3 deletions(-)

diff --git a/ui/hooks/bridge/useBridging.test.ts b/ui/hooks/bridge/useBridging.test.ts
index 6c67048e8c8c..d88be31a5428 100644
--- a/ui/hooks/bridge/useBridging.test.ts
+++ b/ui/hooks/bridge/useBridging.test.ts
@@ -20,8 +20,8 @@ jest.mock('../../ducks/bridge/actions', () => ({
 
 const MOCK_METAMETRICS_ID = '0xtestMetaMetricsId';
 
-const renderUseBridging = (mockStoreState: object) =>
-  renderHookWithProvider(() => useBridging(), mockStoreState);
+const renderUseBridging = (mockStoreState: object, pathname?: string) =>
+  renderHookWithProvider(() => useBridging(), mockStoreState, pathname);
 
 describe('useBridging', () => {
   beforeAll(() => {
@@ -52,7 +52,7 @@ describe('useBridging', () => {
         false,
       ],
       [
-        '/cross-chain/swaps/prepare-swap-page?from=eip155:10/erc20:0x8ac76a51cc950d9822d68b83fe1ad97b32cd580d&swaps=true',
+        '/cross-chain/swaps/prepare-swap-page?from=eip155:10/erc20:0x8ac76a51cc950d9822d68b83fe1ad97b32cd580d&to=eip155:10/erc20:0x0b2c639c533813f4aa9d7837caf62653d097ff85&swaps=true',
         {
           iconUrl: 'https://icon.url',
           symbol: 'TEST',
@@ -110,5 +110,96 @@ describe('useBridging', () => {
         expect(openTabSpy).not.toHaveBeenCalled();
       },
     );
+
+    // @ts-expect-error This is missing from the Mocha type definitions
+    it.each([
+      [
+        '/',
+        '/cross-chain/swaps/prepare-swap-page?from=eip155:1/slip44:60&swaps=true',
+        undefined,
+        'Home',
+        true,
+      ],
+      [
+        '/asset/0xa/',
+        '/cross-chain/swaps/prepare-swap-page?from=eip155:1/slip44:60&swaps=true',
+        ETH_SWAPS_TOKEN_OBJECT,
+        MetaMetricsSwapsEventSource.TokenView,
+        true,
+      ],
+      [
+        '/asset/0xa/0x8ac76a51cc950d9822d68b83fe1ad97b32cd580d',
+        '/cross-chain/swaps/prepare-swap-page?from=eip155:10/erc20:0x8ac76a51cc950d9822d68b83fe1ad97b32cd580d&to=eip155:10/erc20:0x0b2c639c533813f4aa9d7837caf62653d097ff85&swaps=true',
+        {
+          iconUrl: 'https://icon.url',
+          symbol: 'TEST',
+          address: toChecksumAddress(
+            '0x8ac76a51cc950d9822d68b83fe1ad97b32cd580D',
+          ),
+          balance: '0x5f5e100',
+          string: '123',
+          chainId: '0xa',
+          decimals: 18,
+        },
+        MetaMetricsSwapsEventSource.TokenView,
+        true,
+      ],
+    ])(
+      'should open swap with correct token pair when pathname is %s',
+      async (
+        pathname: string,
+        expectedUrl: string,
+        token: string,
+        location: string,
+        isSwap: boolean,
+      ) => {
+        const openTabSpy = jest.spyOn(global.platform, 'openTab');
+        const { result, history } = renderUseBridging({
+          metamask: {
+            useExternalServices: true,
+            ...mockNetworkState({ chainId: CHAIN_IDS.MAINNET }),
+            metaMetricsId: MOCK_METAMETRICS_ID,
+            remoteFeatureFlags: {
+              bridgeConfig: {
+                bip44DefaultPairs: {
+                  eip155: {
+                    standard: {
+                      'eip155:1/slip44:60':
+                        'eip155:1/erc20:0x0b2c639c533813f4aa9d7837caf62653d097ff84',
+                    },
+                  },
+                },
+                refreshRate: 5000,
+                minimumVersion: '0.0.0',
+                maxRefreshCount: 5,
+                chains: {
+                  '1': {
+                    isActiveSrc: true,
+                    isActiveDest: true,
+                  },
+                  '10': {
+                    isActiveSrc: true,
+                    isActiveDest: true,
+                  },
+                },
+              },
+            },
+            internalAccounts: {
+              selectedAccount: '0xabc',
+              accounts: { '0xabc': { metadata: { keyring: {} } } },
+            },
+            pathname,
+          },
+        });
+        const mockHistoryPush = jest.spyOn(history, 'push');
+
+        result.current.openBridgeExperience(location, token, isSwap);
+
+        expect(mockDispatch.mock.calls).toHaveLength(2);
+        expect(mockHistoryPush.mock.calls).toHaveLength(1);
+        expect(mockHistoryPush).toHaveBeenCalledWith(expectedUrl);
+        expect(openTabSpy).not.toHaveBeenCalled();
+      },
+    );
   });
 });

From 32db4873868a1c91afd44e3921485f9d37cf200d Mon Sep 17 00:00:00 2001
From: Micaela Estabillo <micaela.estabillo@consensys.net>
Date: Tue, 23 Sep 2025 10:23:55 -0700
Subject: [PATCH 8/8] chore: comments

---
 ui/ducks/bridge/selectors.ts        | 1 -
 ui/hooks/bridge/useBridging.test.ts | 4 ++--
 ui/hooks/bridge/useBridging.ts      | 7 +++----
 3 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/ui/ducks/bridge/selectors.ts b/ui/ducks/bridge/selectors.ts
index bec99ec94424..3ae779dc2970 100644
--- a/ui/ducks/bridge/selectors.ts
+++ b/ui/ducks/bridge/selectors.ts
@@ -289,7 +289,6 @@ export const getToToken = createSelector(
     if (toToken) {
       return toToken;
     }
-    // TODO if fromToken is in bip44Defaults, return its mapped toToken
     // Otherwise, determine the default token to use based on fromToken and toChain
     const defaultToken = getDefaultToToken(
       formatChainIdToCaip(toChain.chainId),
diff --git a/ui/hooks/bridge/useBridging.test.ts b/ui/hooks/bridge/useBridging.test.ts
index d88be31a5428..af5a20eea70f 100644
--- a/ui/hooks/bridge/useBridging.test.ts
+++ b/ui/hooks/bridge/useBridging.test.ts
@@ -122,7 +122,7 @@ describe('useBridging', () => {
       ],
       [
         '/asset/0xa/',
-        '/cross-chain/swaps/prepare-swap-page?from=eip155:1/slip44:60&swaps=true',
+        '/cross-chain/swaps/prepare-swap-page?from=eip155:10/slip44:60&swaps=true',
         ETH_SWAPS_TOKEN_OBJECT,
         MetaMetricsSwapsEventSource.TokenView,
         true,
@@ -157,7 +157,7 @@ describe('useBridging', () => {
         const { result, history } = renderUseBridging({
           metamask: {
             useExternalServices: true,
-            ...mockNetworkState({ chainId: CHAIN_IDS.MAINNET }),
+            ...mockNetworkState({ chainId: CHAIN_IDS.OPTIMISM }),
             metaMetricsId: MOCK_METAMETRICS_ID,
             remoteFeatureFlags: {
               bridgeConfig: {
diff --git a/ui/hooks/bridge/useBridging.ts b/ui/hooks/bridge/useBridging.ts
index 8104cbd9f3b3..954378a26d2c 100644
--- a/ui/hooks/bridge/useBridging.ts
+++ b/ui/hooks/bridge/useBridging.ts
@@ -67,15 +67,14 @@ const useBridging = () => {
         defaultTokenPair ?? [];
 
       const srcAssetIdToUse =
-        // If srcToken is present, use the srcToken assetId
         (srcToken
           ? toAssetId(
               srcToken.address,
               formatChainIdToCaip(srcToken.chainId ?? providerConfig.chainId),
             )
-          : // Otherwise, use the default bip44 src asset id
-            defaultBip44SrcAssetId) ??
-        // Otherwise, use the native asset for Ethereum mainnet
+          : defaultBip44SrcAssetId) ??
+        // If neither the srcAsset or default BIP44 default pair are present
+        // use the native asset for Ethereum mainnet
         // This should only happen if the feature flags are unavailable and the
         // user clicks on Swap from the home page
         getNativeAssetForChainId(CHAIN_IDS.MAINNET)?.assetId;