refactor: remove swaps-controller package (#27547)

<!--
Please submit this PR as a draft initially.
Do not mark it as "Ready for review" until the template has been
completely filled out, and PR status checks have passed at least once.
-->

## **Description**

<!--
Write a short description of the changes included in this pull request,
also include relevant motivation and context. Have in mind the following
questions:
1. What is the reason for the change?
2. What is the improvement/solution?
-->

The `@metamask/swaps-controller` package is no longer needed — swaps
functionality is now handled by `BridgeController` and
`BridgeStatusController`. This PR removes the package and all associated
wiring:

- **Deleted** the controller initializer (`swaps-controller-init.ts`)
and its messenger (`swaps-controller-messenger.ts`), along with their
tests.
- **Removed** `SwapsController` from the Engine initialization, types,
state-change event constants, and Sentry state mask.
- **Cleaned up** the swaps Redux reducer by removing all selectors that
read from `SwapsController` state (e.g. `swapsTokensObjectSelector`,
`swapsTokensMultiChainObjectSelector`, `swapsTopAssetsSelector`, etc.)
and the helper functions they depended on.
- **Inlined** the `FeatureFlags` interface and `CHAIN_ID_TO_NAME_MAP`
constant locally in `app/reducers/swaps/utils.ts` so the remaining
liveness logic no longer imports from the deleted package.
- **Added** migration 126 to strip `SwapsController` from persisted
`backgroundState` on upgrade.
- **Removed** `SwapsController` entries from test fixtures
(`initial-background-state.json`, `default-fixture.json`), snapshot
files, and mock states (Bridge, EngineService).
- **Removed** the `@metamask/swaps-controller` dependency from
`package.json` and cleaned up `yarn.lock` (also drops transitive
`@metamask/utils@10`, `human-standard-token-abi`).

## **Changelog**

<!--
If this PR is not End-User-Facing and should not show up in the
CHANGELOG, you can choose to either:
1. Write `CHANGELOG entry: null`
2. Label with `no-changelog`

If this PR is End-User-Facing, please write a short User-Facing
description in the past tense like:
`CHANGELOG entry: Added a new tab for users to see their NFTs`
`CHANGELOG entry: Fixed a bug that was causing some NFTs to flicker`

(This helps the Release Engineer do their job more quickly and
accurately)
-->

CHANGELOG entry: null

## **Related issues**

Fixes: https://consensyssoftware.atlassian.net/browse/SWAPS-3927

## **Manual testing steps**

N/A — This is an internal refactoring with no UI or behavior changes.
Swaps functionality continues to work through BridgeController. Existing
unit tests and migration tests cover the removal.

## **Screenshots/Recordings**

<!-- If applicable, add screenshots and/or recordings to visualize the
before and after of your change. -->

### **Before**

N/A

### **After**

N/A

## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I've included tests if applicable
- [x] I've documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I've applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

<!-- Generated with the help of the pr-description AI skill -->

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Removes a controller from Engine wiring, persisted state, and selector
surface area; any missed references could cause runtime init or
state-shape regressions despite being a deletion-focused change.
> 
> **Overview**
> Removes the legacy `SwapsController` integration end-to-end: Engine
init/messenger/type wiring is deleted, state-change subscriptions and
Sentry masking are updated, and the `@metamask/swaps-controller`
dependency is dropped.
> 
> Strips `SwapsController`-backed Redux selectors and test/mocked state
that depended on its persisted background state, and adds migration
`127` to delete `engine.backgroundState.SwapsController` on upgrade.
Fixtures, snapshots, and Bridge/EngineService tests are updated
accordingly, with swaps liveness utilities inlining the needed
feature-flag types and chain-name mapping.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
23265cb. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: GeorgeGkas

.agents/skills/e2e-test/SKILL.md

@@ -89,10 +89,10 @@ Step 5 → Iterate (fix → lint → run) until green
 
 Documentation is split by **action**. Open only the reference that matches what you are doing.
 
-| Action                                        | File                                                       | When to open it                                                                                   |
-| --------------------------------------------- | ---------------------------------------------------------- | ------------------------------------------------------------------------------------------------- |
-| **Writing or updating a spec**                | [references/writing-tests.md](references/writing-tests.md) | New spec file, spec structure, FixtureBuilder patterns, smoke/regression templates.               |
-| **Page Objects and selectors**                | [references/page-objects.md](references/page-objects.md)   | Create or update POM classes, selector/testId conventions, Matchers/Gestures/Assertions API.      |
-| **API and feature flag mocking**              | [references/mocking.md](references/mocking.md)             | testSpecificMock, setupRemoteFeatureFlagsMock, setupMockRequest, shared mock files.               |
+| Action                                        | File                                                                | When to open it                                                                                                    |
+| --------------------------------------------- | ------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------ |
+| **Writing or updating a spec**                | [references/writing-tests.md](references/writing-tests.md)          | New spec file, spec structure, FixtureBuilder patterns, smoke/regression templates.                                |
+| **Page Objects and selectors**                | [references/page-objects.md](references/page-objects.md)            | Create or update POM classes, selector/testId conventions, Matchers/Gestures/Assertions API.                       |
+| **API and feature flag mocking**              | [references/mocking.md](references/mocking.md)                      | testSpecificMock, setupRemoteFeatureFlagsMock, setupMockRequest, shared mock files.                                |
 | **MetaMetrics / analytics expectations**      | [tests/docs/analytics-e2e.md](../../../tests/docs/analytics-e2e.md) | `analyticsExpectations` on `withFixtures`, declarative checks, presets in `tests/helpers/analytics/expectations/`. |
-| **Running tests, debugging, fixing failures** | [references/running-tests.md](references/running-tests.md) | Build check, detox run commands, lint/tsc, common failures table, retry patterns, iteration loop. |
+| **Running tests, debugging, fixing failures** | [references/running-tests.md](references/running-tests.md)          | Build check, detox run commands, lint/tsc, common failures table, retry patterns, iteration loop.                  |

app/components/UI/Bridge/Views/BridgeView/BridgeView.test.tsx

@@ -98,11 +98,6 @@ jest.mock('../../../../../core/Engine', () => {
       unsubscribe: jest.fn(),
     },
     context: {
-      SwapsController: {
-        fetchAggregatorMetadataWithCache: jest.fn(),
-        fetchTopAssetsWithCache: jest.fn(),
-        fetchTokenWithCache: jest.fn(),
-      },
       KeyringController: {
         state: {
           keyrings: [

app/components/UI/Bridge/_mocks_/initialState.ts

@@ -609,35 +609,6 @@ export const initialState = {
           },
         },
       },
-      SwapsController: {
-        chainCache: {
-          [ethChainId]: {
-            aggregatorMetadata: null,
-            tokens: null,
-            topAssets: [
-              {
-                address: ethToken1Address,
-                symbol: 'TOKEN1',
-              },
-              {
-                address: ethToken2Address,
-                symbol: 'HELLO',
-              },
-            ],
-            aggregatorMetadataLastFetched: 0,
-            topAssetsLastFetched: 0,
-            tokensLastFetched: 0,
-          },
-          [optimismChainId]: {
-            aggregatorMetadata: null,
-            tokens: null,
-            topAssets: null,
-            aggregatorMetadataLastFetched: 0,
-            topAssetsLastFetched: 0,
-            tokensLastFetched: 0,
-          },
-        },
-      },
       KeyringController: {
         vault: '',
         isUnlocked: true,

app/core/Engine/Engine.ts

@@ -164,7 +164,6 @@ import { earnControllerInit } from './controllers/earn-controller-init';
 import { geolocationApiServiceInit } from './controllers/geolocation-api-service-init';
 import { geolocationControllerInit } from './controllers/geolocation-controller';
 import { rewardsDataServiceInit } from './controllers/rewards-data-service-init';
-import { swapsControllerInit } from './controllers/swaps-controller-init';
 import { remoteFeatureFlagControllerInit } from './controllers/remote-feature-flag-controller-init';
 import { errorReportingServiceInit } from './controllers/error-reporting-service-init';
 import { storageServiceInit } from './controllers/storage-service/storage-service-init';
@@ -334,7 +333,6 @@ export class Engine {
         BridgeStatusController: bridgeStatusControllerInit,
         NftController: nftControllerInit,
         NftDetectionController: nftDetectionControllerInit,
-        SwapsController: swapsControllerInit,
         ///: BEGIN:ONLY_INCLUDE_IF(preinstalled-snaps,external-snaps)
         ExecutionService: executionServiceInit,
         CronjobController: cronjobControllerInit,
@@ -450,7 +448,6 @@ export class Engine {
     const bridgeController = controllersByName.BridgeController;
     const nftController = controllersByName.NftController;
     const nftDetectionController = controllersByName.NftDetectionController;
-    const swapsController = controllersByName.SwapsController;
     const networkController = controllersByName.NetworkController;
 
     ///: BEGIN:ONLY_INCLUDE_IF(preinstalled-snaps,external-snaps)
@@ -530,7 +527,6 @@ export class Engine {
       TransactionController: this.transactionController,
       TransactionPayController: controllersByName.TransactionPayController,
       SmartTransactionsController: this.smartTransactionsController,
-      SwapsController: swapsController,
       GasFeeController: this.gasFeeController,
       GatorPermissionsController: gatorPermissionsController,
       ApprovalController: approvalController,
@@ -1351,7 +1347,6 @@ export default {
       SelectedNetworkController,
       SignatureController,
       SmartTransactionsController,
-      SwapsController,
       TokenBalancesController,
       TokenListController,
       TokenRatesController,
@@ -1421,7 +1416,6 @@ export default {
       SelectedNetworkController: SelectedNetworkController.state,
       SignatureController: SignatureController.state,
       SmartTransactionsController: SmartTransactionsController.state,
-      SwapsController: SwapsController.state,
       TokenBalancesController: TokenBalancesController.state,
       TokenListController: TokenListController.state,
       TokenRatesController: TokenRatesController.state,

app/core/Engine/constants.ts

@@ -47,7 +47,6 @@ export const BACKGROUND_STATE_CHANGE_EVENT_NAMES = [
   'SelectedNetworkController:stateChange',
   'SignatureController:stateChange',
   'SmartTransactionsController:stateChange',
-  'SwapsController:stateChange',
   'TokenBalancesController:stateChange',
   'TokenListController:stateChange',
   'TokenRatesController:stateChange',
@@ -92,22 +91,6 @@ export const BACKGROUND_STATE_CHANGE_EVENT_NAMES = [
   'ComplianceController:stateChange',
 ] as const;
 
-export const swapsSupportedChainIds = [
-  NETWORK_CHAIN_ID.MAINNET,
-  NETWORK_CHAIN_ID.BSC,
-  NETWORK_CHAIN_ID.POLYGON,
-  NETWORK_CHAIN_ID.AVALANCHE,
-  NETWORK_CHAIN_ID.ARBITRUM,
-  NETWORK_CHAIN_ID.OPTIMISM,
-  NETWORK_CHAIN_ID.ZKSYNC_ERA,
-  NETWORK_CHAIN_ID.LINEA_MAINNET,
-  NETWORK_CHAIN_ID.BASE,
-  NETWORK_CHAIN_ID.SEI,
-  NETWORK_CHAIN_ID.MONAD,
-  NETWORK_CHAIN_ID.HYPE,
-  NETWORK_CHAIN_ID.MEGAETH_MAINNET,
-];
-
 export const MAINNET_DISPLAY_NAME = 'Ethereum';
 export const LINEA_MAINNET_DISPLAY_NAME = 'Linea';
 export const POLYGON_DISPLAY_NAME = 'Polygon';

app/core/Engine/controllers/swaps-controller-init.test.ts

@@ -118,7 +118,6 @@ import {
 import { getGeolocationApiServiceMessenger } from './geolocation-api-service-messenger';
 import { getGeolocationControllerMessenger } from './geolocation-controller-messenger';
 import { getRewardsDataServiceMessenger } from './rewards-data-service-messenger';
-import { getSwapsControllerMessenger } from './swaps-controller-messenger';
 import {
   getDelegationControllerInitMessenger,
   getDelegationControllerMessenger,
@@ -372,10 +371,6 @@ export const CONTROLLER_MESSENGERS = {
     getMessenger: getSmartTransactionsControllerMessenger,
     getInitMessenger: getSmartTransactionsControllerInitMessenger,
   },
-  SwapsController: {
-    getMessenger: getSwapsControllerMessenger,
-    getInitMessenger: noop,
-  },
   NetworkEnablementController: {
     getMessenger: getNetworkEnablementControllerMessenger,
     getInitMessenger: noop,