fix(assets-controllers): revert Snap account-asset enrichment added in 109.3.0 (#9454)

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## References

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## Checklist

- [ ] I've updated the test suite for new or updated code as appropriate
- [ ] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [ ] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/processes/updating-changelogs.md)
- [ ] I've introduced [breaking
changes](https://github.com/MetaMask/core/tree/main/docs/processes/breaking-changes.md)
in this PR and have prepared draft pull requests for clients and
consumer packages to resolve them

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **High Risk**
> Marked **BREAKING** in the changelog: removes exported types, changes
messenger event payloads, and alters balance merge semantics—consumers
relying on 109.3.0 enrichment or `refreshed` must migrate.
> 
> **Overview**
> **Breaking revert** of the 109.3.0 Snap `getAccountAssetInfo` flow:
multichain balance rows are again `{ amount, unit }` only, with
enrichment expected in the unified assets controller on the client.
> 
> `MultichainBalancesController` drops snap enrichment calls, the
`account-asset-info` module, and exported types `AccountAssetInfo` /
`MultichainAccountBalance`. Asset-list handling no longer treats
`refreshed` assets (only `added` / `removed`), and balance merges on
updates are simplified (e.g. full replace on `updateBalance`, shallow
assign on `accountBalancesUpdated`).
> 
> `MultichainAssetsController:accountAssetListUpdated` no longer emits a
`refreshed` list for snap adds that are already tracked; its payload
aligns with `AccountsController:accountAssetListUpdated`. Token
selectors stop exposing `accountAssetInfo` on `Asset` items. Tests and
changelog document the breaking removals; balance tests add coverage for
pruning stale balances when assets are removed.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
2263d69. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: stanleyyconsensys

packages/assets-controllers/CHANGELOG.md

@@ -13,6 +13,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - Add `Robinhood` in `SupportedTokenDetectionNetworks`
   - Add Robinhood BalanceFetcher address in `SINGLE_CALL_BALANCES_ADDRESS_BY_CHAINID`
 
+### Removed
+
+- **BREAKING:** Revert Snap account-asset enrichment added in 109.3.0 ([#9454](https://github.com/MetaMask/core/pull/9454))
+  - `MultichainBalancesController` no longer fetches or stores `accountAssetInfo` on balance rows; enrichment is handled client-side by the unified assets controller.
+  - Remove exported types `AccountAssetInfo` and `MultichainAccountBalance`.
+  - Remove optional `accountAssetInfo` from selector `Asset` items.
+  - `MultichainAssetsController:accountAssetListUpdated` no longer includes a `refreshed` asset list for already-tracked snap adds;
+
 ## [109.4.1]
 
 ### Changed

packages/assets-controllers/src/MultichainAssetsController/MultichainAssetsController.test.ts

@@ -796,50 +796,6 @@ describe('MultichainAssetsController', () => {
       });
     });
 
-    it('publishes refreshed assets when snap reports adds that are already tracked', async () => {
-      const mockSolanaAccountId1 = 'account1';
-      const existingToken =
-        'solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1/token:Gh9ZwEmdLJ8DscKNTkTqPbNwLNNBjuSzaG9Vp2KGtKJr' as CaipAssetType;
-      const { controller, messenger } = setupController({
-        state: {
-          accountsAssets: {
-            [mockSolanaAccountId1]: mockHandleRequestOnAssetsLookupReturnValue,
-          },
-          assetsMetadata: mockGetMetadataReturnValue,
-          allIgnoredAssets: {},
-        } as MultichainAssetsControllerState,
-      });
-
-      const eventListener = jest.fn();
-      messenger.subscribe(
-        'MultichainAssetsController:accountAssetListUpdated',
-        eventListener,
-      );
-
-      messenger.publish('AccountsController:accountAssetListUpdated', {
-        assets: {
-          [mockSolanaAccountId1]: {
-            added: [existingToken],
-            removed: [],
-          },
-        },
-      });
-      await jestAdvanceTime({ duration: 1 });
-
-      expect(
-        controller.state.accountsAssets[mockSolanaAccountId1],
-      ).toStrictEqual(mockHandleRequestOnAssetsLookupReturnValue);
-      expect(eventListener).toHaveBeenCalledWith({
-        assets: {
-          [mockSolanaAccountId1]: {
-            added: [],
-            removed: [],
-            refreshed: [existingToken],
-          },
-        },
-      });
-    });
-
     it('updates the assets list for an account when a an asset is removed', async () => {
       const mockSolanaAccountId1 = 'account1';
       const mockSolanaAccountId2 = 'account2';

packages/assets-controllers/src/MultichainAssetsController/MultichainAssetsController.ts

@@ -61,26 +61,9 @@ export type AssetMetadataResponse = {
   };
 };
 
-/**
- * Per-account asset list delta published by {@link MultichainAssetsController}.
- */
-export type MultichainAssetsControllerAccountAssetListDelta = {
-  added: CaipAssetType[];
-  removed: CaipAssetType[];
-  /**
-   * Snap-reported adds that are already tracked in MAC state. Downstream
-   * controllers should refresh balances and enrichment for these assets.
-   */
-  refreshed?: CaipAssetType[];
-};
-
-export type MultichainAssetsControllerAccountAssetListUpdatedPayload = {
-  assets: Record<string, MultichainAssetsControllerAccountAssetListDelta>;
-};
-
 export type MultichainAssetsControllerAccountAssetListUpdatedEvent = {
   type: `${typeof controllerName}:accountAssetListUpdated`;
-  payload: [MultichainAssetsControllerAccountAssetListUpdatedPayload];
+  payload: AccountsControllerAccountAssetListUpdatedEvent['payload'];
 };
 
 /**
@@ -468,9 +451,7 @@ export class MultichainAssetsController extends StaticIntervalPollingController<
     this.#assertControllerMutexIsLocked();
 
     const assetsForMetadataRefresh = new Set<CaipAssetType>([]);
-    const accountsAndAssetsForState: AccountAssetListUpdatedEventPayload['assets'] =
-      {};
-    const accountsAndAssetsToPublish: MultichainAssetsControllerAccountAssetListUpdatedPayload['assets'] =
+    const accountsAndAssetsToUpdate: AccountAssetListUpdatedEventPayload['assets'] =
       {};
     for (const [accountId, { added, removed }] of Object.entries(
       event.assets,
@@ -487,13 +468,6 @@ export class MultichainAssetsController extends StaticIntervalPollingController<
             !this.#isAssetIgnored(asset, accountId),
         );
 
-        const refreshedAssets = added.filter(
-          (asset): asset is CaipAssetType =>
-            existing.includes(asset) &&
-            isCaipAssetType(asset) &&
-            !this.#isAssetIgnored(asset, accountId),
-        );
-
         // Filter out tokens that cannot be verified or are flagged malicious
         const filteredToBeAddedAssets =
           await this.#filterBlockaidSpamTokensOnAdd(preFilteredToBeAddedAssets);
@@ -507,26 +481,12 @@ export class MultichainAssetsController extends StaticIntervalPollingController<
           filteredToBeAddedAssets.length > 0 ||
           filteredToBeRemovedAssets.length > 0
         ) {
-          accountsAndAssetsForState[accountId] = {
+          accountsAndAssetsToUpdate[accountId] = {
             added: filteredToBeAddedAssets,
             removed: filteredToBeRemovedAssets,
           };
         }
 
-        if (
-          filteredToBeAddedAssets.length > 0 ||
-          filteredToBeRemovedAssets.length > 0 ||
-          refreshedAssets.length > 0
-        ) {
-          accountsAndAssetsToPublish[accountId] = {
-            added: filteredToBeAddedAssets,
-            removed: filteredToBeRemovedAssets,
-            ...(refreshedAssets.length > 0
-              ? { refreshed: refreshedAssets }
-              : {}),
-          };
-        }
-
         for (const asset of existing) {
           assetsForMetadataRefresh.add(asset);
         }
@@ -541,7 +501,7 @@ export class MultichainAssetsController extends StaticIntervalPollingController<
 
     this.update((state) => {
       for (const [accountId, { added, removed }] of Object.entries(
-        accountsAndAssetsForState,
+        accountsAndAssetsToUpdate,
       )) {
         const assets = new Set([
           ...(state.accountsAssets[accountId] || []),
@@ -558,11 +518,9 @@ export class MultichainAssetsController extends StaticIntervalPollingController<
     // Trigger fetching metadata for new assets
     await this.#refreshAssetsMetadata(Array.from(assetsForMetadataRefresh));
 
-    if (Object.keys(accountsAndAssetsToPublish).length > 0) {
-      this.messenger.publish(`${controllerName}:accountAssetListUpdated`, {
-        assets: accountsAndAssetsToPublish,
-      });
-    }
+    this.messenger.publish(`${controllerName}:accountAssetListUpdated`, {
+      assets: accountsAndAssetsToUpdate,
+    });
   }
 
   /**