fix: add assets-controller temp state migration healing

packages/assets-controller/CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fetch balances when switching account groups, enabling RPC-only networks, or after a new account is added to the account tree ([#9388](https://github.com/MetaMask/core/pull/9388))
+- Add temporary `tempMigrateAssetsInfoMetadataAssets3346` constructor option that heals `assetsInfo` metadata (and custom-asset tracking) wiped by a prior defect for tokens on niche EVM chains, using legacy `TokensController` state provided by the host ([#9393](https://github.com/MetaMask/core/pull/9393))
 
 ## [10.0.1]
 

packages/assets-controller/src/AssetsController.test.ts

@@ -22,6 +22,7 @@ import type { PriceDataSourceConfig } from './data-sources/PriceDataSource';
 import { PriceDataSource } from './data-sources/PriceDataSource';
 import { TokenDataSource } from './data-sources/TokenDataSource';
 import { buildDefaultAssetsInfo } from './defaults';
+import type { Assets3346MigrationState } from './migrations/healAssetsInfoMetadata';
 import type {
   Caip19AssetId,
   AccountId,
@@ -125,6 +126,8 @@ type WithControllerOptions = {
     trace: TraceCallback;
     priceDataSourceConfig: PriceDataSourceConfig;
     isEnabled: () => boolean;
+    captureException: (error: Error) => void;
+    tempMigrateAssetsInfoMetadataAssets3346: () => Assets3346MigrationState;
   }>;
 };
 
@@ -320,6 +323,123 @@ describe('AssetsController', () => {
       });
     });
 
+    describe('temporary assetsInfo metadata healing (tempMigrateAssetsInfoMetadataAssets3346)', () => {
+      const HEALED_ASSET_ID =
+        'eip155:14/erc20:0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48' as Caip19AssetId;
+      const LEGACY_ACCOUNT_ADDRESS =
+        '0x1234567890123456789012345678901234567890';
+      const legacyState: Assets3346MigrationState = {
+        TokensController: {
+          allTokens: {
+            // Flare (0xe / 14) is not covered by the Accounts API.
+            '0xe': {
+              [LEGACY_ACCOUNT_ADDRESS]: [
+                {
+                  address: '0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48',
+                  symbol: 'TST',
+                  name: 'Test Token',
+                  decimals: 18,
+                },
+              ],
+            },
+          },
+        },
+        AccountsController: {
+          internalAccounts: {
+            accounts: {
+              [MOCK_ACCOUNT_ID]: { address: LEGACY_ACCOUNT_ADDRESS },
+            },
+          },
+        },
+      };
+
+      it('heals wiped niche-chain token metadata from legacy state on construction', async () => {
+        await withController(
+          {
+            controllerOptions: {
+              tempMigrateAssetsInfoMetadataAssets3346: () => legacyState,
+            },
+          },
+          ({ controller }) => {
+            expect(controller.state.assetsInfo[HEALED_ASSET_ID]).toStrictEqual({
+              type: 'erc20',
+              symbol: 'TST',
+              name: 'Test Token',
+              decimals: 18,
+            });
+            expect(
+              controller.state.customAssets[MOCK_ACCOUNT_ID],
+            ).toStrictEqual([HEALED_ASSET_ID]);
+          },
+        );
+      });
+
+      it('does not overwrite existing assetsInfo metadata', async () => {
+        const existingMetadata: FungibleAssetMetadata = {
+          type: 'erc20',
+          symbol: 'EXISTING',
+          name: 'Existing Token',
+          decimals: 6,
+        };
+
+        await withController(
+          {
+            state: {
+              assetsInfo: { [HEALED_ASSET_ID]: existingMetadata },
+            },
+            controllerOptions: {
+              tempMigrateAssetsInfoMetadataAssets3346: () => legacyState,
+            },
+          },
+          ({ controller }) => {
+            expect(controller.state.assetsInfo[HEALED_ASSET_ID]).toStrictEqual(
+              existingMetadata,
+            );
+          },
+        );
+      });
+
+      it('leaves state untouched when the legacy state has nothing restorable', async () => {
+        await withController(
+          {
+            controllerOptions: {
+              tempMigrateAssetsInfoMetadataAssets3346: () => ({}),
+            },
+          },
+          ({ controller }) => {
+            expect(controller.state).toStrictEqual(
+              getDefaultAssetsControllerState(),
+            );
+          },
+        );
+      });
+
+      it('reports getter errors via captureException without breaking construction', async () => {
+        const captureException = jest.fn();
+
+        await withController(
+          {
+            controllerOptions: {
+              captureException,
+              tempMigrateAssetsInfoMetadataAssets3346: () => {
+                throw new Error('legacy state unavailable');
+              },
+            },
+          },
+          ({ controller }) => {
+            expect(controller.state).toStrictEqual(
+              getDefaultAssetsControllerState(),
+            );
+            expect(captureException).toHaveBeenCalledWith(
+              expect.objectContaining({
+                message: expect.stringContaining('legacy state unavailable'),
+              }),
+            );
+          },
+        );
+      });
+    });
+
     it('initializes normally when isEnabled returns true', async () => {
       await withController(({ controller, messenger }) => {
         // Controller should have default state

packages/assets-controller/src/AssetsController.ts

@@ -107,6 +107,8 @@ import {
   createParallelMiddleware,
 } from './middlewares/ParallelMiddleware';
 import { RpcFallbackMiddleware } from './middlewares/RpcFallbackMiddleware';
+import type { Assets3346MigrationState } from './migrations/healAssetsInfoMetadata';
+import { tempHealAssetsInfoMetadata } from './migrations/healAssetsInfoMetadata';
 import type {
   AccountId,
   AssetPreferences,
@@ -435,6 +437,12 @@ export type AssetsControllerOptions = {
    * Defaults to () => true.
    */
   isOnboarded?: () => boolean;
+
+  /**
+   * TEMPORARY — will be removed in a future release.
+   * Issue: https://consensyssoftware.atlassian.net/browse/ASSETS-3346
+   */
+  tempMigrateAssetsInfoMetadataAssets3346?: () => Assets3346MigrationState;
 };
 
 // ============================================================================
@@ -849,6 +857,7 @@ export class AssetsController extends BaseController<
     priceDataSourceConfig,
     stakedBalanceDataSourceConfig,
     isOnboarded,
+    tempMigrateAssetsInfoMetadataAssets3346,
   }: AssetsControllerOptions) {
     super({
       name: CONTROLLER_NAME,
@@ -868,6 +877,18 @@ export class AssetsController extends BaseController<
     this.#queryApiClient = queryApiClient;
     const rpcConfig = rpcDataSourceConfig ?? {};
 
+    // TEMPORARY: heal assetsInfo metadata wiped by a prior defect
+    // (see extension migration #215 / ASSETS-3346). Remove in a future release.
+    if (tempMigrateAssetsInfoMetadataAssets3346) {
+      this.update(() =>
+        tempHealAssetsInfoMetadata({
+          state: this.state,
+          getMigrationState: tempMigrateAssetsInfoMetadataAssets3346,
+          captureException,
+        }),
+      );
+    }
+
     this.#initializeNativeAssetsMap(queryApiClient);
 
     this.#onActiveChainsUpdated = (