diff --git a/packages/metro-file-map/src/__tests__/index-test.js b/packages/metro-file-map/src/__tests__/index-test.js
index 6db43b0238..1df6420416 100644
--- a/packages/metro-file-map/src/__tests__/index-test.js
+++ b/packages/metro-file-map/src/__tests__/index-test.js
@@ -94,7 +94,7 @@ jest.mock('../crawlers/watchman', () => ({
               '', // dependencies
               hash,
               typeof contentOrLink !== 'string' ? 1 : 0,
-              '', // Haste name
+              null, // Haste name
             ]);
           }
         } else {
@@ -524,7 +524,7 @@ describe('FileMap', () => {
           'Melon',
           null,
           0,
-          '',
+          null,
         ],
         [path.join('vegetables', 'Melon.js')]: [
           32,
@@ -582,7 +582,7 @@ describe('FileMap', () => {
         // $FlowFixMe[missing-local-annot]
         node.mockImplementation(options => {
           // The node crawler returns "null" for the SHA-1.
-          const changedFiles = createMap({
+          const changedFiles = createMap<FileMetadata>({
             [path.join('fruits', 'Banana.js')]: [
               32,
               42,
@@ -617,7 +617,7 @@ describe('FileMap', () => {
               'Melon',
               null,
               0,
-              '',
+              null,
             ],
             [path.join('vegetables', 'Melon.js')]: [
               32,
@@ -637,7 +637,7 @@ describe('FileMap', () => {
                     '',
                     null,
                     1,
-                    '',
+                    null,
                   ],
                 }
               : null),
@@ -695,7 +695,7 @@ describe('FileMap', () => {
               'Melon',
               '8d40afbb6e2dc78e1ba383b6d02cafad35cceef2',
               0,
-              '',
+              null,
             ],
             [path.join('vegetables', 'Melon.js')]: [
               32,
@@ -714,7 +714,7 @@ describe('FileMap', () => {
                     1,
                     '',
                     null,
-                    '',
+                    null,
                   ],
                 }
               : null),
@@ -1422,7 +1422,7 @@ describe('FileMap', () => {
     // $FlowFixMe[missing-local-annot]
     watchman.mockImplementation(async options => {
       const {changedFiles} = await mockImpl(options);
-      changedFiles.set(invalidFilePath, [34, 44, 0, '', null, 0, '']);
+      changedFiles.set(invalidFilePath, [34, 44, 0, '', null, 0, null]);
       return {
         changedFiles,
         removedFiles: new Set(),
@@ -1466,9 +1466,8 @@ describe('FileMap', () => {
           computeDependencies: true,
           computeSha1: false,
           dependencyExtractor,
-          enableHastePackages: true,
           filePath: path.join('/', 'project', 'fruits', 'Banana.js'),
-          hasteImplModulePath: undefined,
+          isNodeModules: false,
           maybeReturnContent: false,
         },
       ],
@@ -1477,9 +1476,8 @@ describe('FileMap', () => {
           computeDependencies: true,
           computeSha1: false,
           dependencyExtractor,
-          enableHastePackages: true,
           filePath: path.join('/', 'project', 'fruits', 'Pear.js'),
-          hasteImplModulePath: undefined,
+          isNodeModules: false,
           maybeReturnContent: false,
         },
       ],
@@ -1488,9 +1486,8 @@ describe('FileMap', () => {
           computeDependencies: true,
           computeSha1: false,
           dependencyExtractor,
-          enableHastePackages: true,
           filePath: path.join('/', 'project', 'fruits', 'Strawberry.js'),
-          hasteImplModulePath: undefined,
+          isNodeModules: false,
           maybeReturnContent: false,
         },
       ],
@@ -1499,9 +1496,8 @@ describe('FileMap', () => {
           computeDependencies: true,
           computeSha1: false,
           dependencyExtractor,
-          enableHastePackages: true,
           filePath: path.join('/', 'project', 'fruits', '__mocks__', 'Pear.js'),
-          hasteImplModulePath: undefined,
+          isNodeModules: false,
           maybeReturnContent: false,
         },
       ],
@@ -1510,9 +1506,8 @@ describe('FileMap', () => {
           computeDependencies: true,
           computeSha1: false,
           dependencyExtractor,
-          enableHastePackages: true,
           filePath: path.join('/', 'project', 'vegetables', 'Melon.js'),
-          hasteImplModulePath: undefined,
+          isNodeModules: false,
           maybeReturnContent: false,
         },
       ],
@@ -1533,7 +1528,7 @@ describe('FileMap', () => {
     node.mockImplementation((() => {
       return Promise.resolve({
         changedFiles: createMap({
-          [path.join('fruits', 'Banana.js')]: [32, 42, 0, '', null, 0, ''],
+          [path.join('fruits', 'Banana.js')]: [32, 42, 0, '', null, 0, null],
         }),
         removedFiles: new Set(),
       });
@@ -1575,7 +1570,7 @@ describe('FileMap', () => {
     node.mockImplementation(() => {
       return Promise.resolve({
         changedFiles: createMap<FileMetadata>({
-          [path.join('fruits', 'Banana.js')]: [32, 42, 0, '', null, 0, ''],
+          [path.join('fruits', 'Banana.js')]: [32, 42, 0, '', null, 0, null],
         }),
         removedFiles: new Set(),
       });
@@ -1681,7 +1676,8 @@ describe('FileMap', () => {
     fm_it('build returns a "live" fileSystem and hasteMap', async hm => {
       const {fileSystem, hasteMap} = await hm.build();
       const filePath = path.join('/', 'project', 'fruits', 'Banana.js');
-      expect(fileSystem.getModuleName(filePath)).toBeDefined();
+      expect(fileSystem.exists(filePath)).toBe(true);
+      expect(hasteMap.getModuleNameByPath(filePath)).toBe('Banana');
       expect(hasteMap.getModule('Banana')).toBe(filePath);
       mockDeleteFile(path.join('/', 'project', 'fruits'), 'Banana.js');
       mockDeleteFile(path.join('/', 'project', 'fruits'), 'Banana.js');
@@ -1698,7 +1694,8 @@ describe('FileMap', () => {
       };
       expect(eventsQueue).toEqual([deletedBanana]);
       // Verify that the initial result has been updated
-      expect(fileSystem.getModuleName(filePath)).toBeNull();
+      expect(fileSystem.exists(filePath)).toBe(false);
+      expect(hasteMap.getModuleNameByPath(filePath)).toBeNull();
       expect(hasteMap.getModule('Banana')).toBeNull();
     });
 
@@ -1765,10 +1762,8 @@ describe('FileMap', () => {
         },
       ]);
       expect(
-        fileSystem.getModuleName(
-          path.join('/', 'project', 'fruits', 'Tomato.js'),
-        ),
-      ).not.toBeNull();
+        fileSystem.exists(path.join('/', 'project', 'fruits', 'Tomato.js')),
+      ).toBe(true);
       expect(hasteMap.getModule('Tomato')).toBeDefined();
       expect(hasteMap.getModule('Pear')).toBe(
         path.join('/', 'project', 'fruits', 'Pear.js'),
@@ -1940,7 +1935,7 @@ describe('FileMap', () => {
         expect(eventsQueue).toEqual([
           {filePath, metadata: MOCK_CHANGE_FILE, type: 'add'},
         ]);
-        expect(fileSystem.getModuleName(filePath)).toBeDefined();
+        expect(fileSystem.exists(filePath)).toBe(true);
       },
     );
 
@@ -1967,7 +1962,7 @@ describe('FileMap', () => {
         expect(eventsQueue).toEqual([
           {filePath, metadata: MOCK_CHANGE_FILE, type: 'change'},
         ]);
-        expect(fileSystem.getModuleName(filePath)).toBeDefined();
+        expect(fileSystem.exists(filePath)).toBe(true);
       },
     );
 
@@ -1990,7 +1985,7 @@ describe('FileMap', () => {
       expect(eventsQueue).toEqual([
         {filePath, metadata: MOCK_DELETE_FILE, type: 'delete'},
       ]);
-      expect(fileSystem.getModuleName(filePath)).toBeDefined();
+      expect(fileSystem.exists(filePath)).toBe(false);
       expect(console.warn).not.toHaveBeenCalled();
       expect(console.error).not.toHaveBeenCalled();
     });
@@ -2025,8 +2020,13 @@ describe('FileMap', () => {
           modifiedTime: 46,
           size: 5,
         });
-        // getModuleName traverses the symlink, verifying the link is read.
-        expect(fileSystem.getModuleName(filePath)).toEqual('Strawberry');
+        // lookup traverses the symlink, verifying the link is read.
+        expect(fileSystem.lookup(filePath)).toEqual(
+          expect.objectContaining({
+            exists: true,
+            realPath: expect.stringMatching(/Strawberry\.js$/),
+          }),
+        );
       },
       {config: {enableSymlinks: true}},
     );
@@ -2044,8 +2044,8 @@ describe('FileMap', () => {
         );
         const realPath = path.join('/', 'project', 'fruits', 'Strawberry.js');
 
-        expect(fileSystem.getModuleName(symlinkPath)).toEqual('Strawberry');
-        expect(fileSystem.getModuleName(realPath)).toEqual('Strawberry');
+        expect(hasteMap.getModuleNameByPath(symlinkPath)).toEqual('Strawberry');
+        expect(hasteMap.getModuleNameByPath(realPath)).toEqual('Strawberry');
         expect(hasteMap.getModule('Strawberry', 'g')).toEqual(realPath);
 
         // Delete the symlink
@@ -2065,8 +2065,8 @@ describe('FileMap', () => {
         // Symlink is deleted without affecting the Haste module or real file.
         expect(fileSystem.exists(symlinkPath)).toBe(false);
         expect(fileSystem.exists(realPath)).toBe(true);
-        expect(fileSystem.getModuleName(symlinkPath)).toEqual(null);
-        expect(fileSystem.getModuleName(realPath)).toEqual('Strawberry');
+        expect(hasteMap.getModuleNameByPath(symlinkPath)).toEqual(null);
+        expect(hasteMap.getModuleNameByPath(realPath)).toEqual('Strawberry');
         expect(hasteMap.getModule('Strawberry', 'g')).toEqual(realPath);
       },
       {config: {enableSymlinks: true}},
@@ -2075,7 +2075,7 @@ describe('FileMap', () => {
     fm_it(
       'correctly tracks changes to both platform-specific versions of a single module name',
       async hm => {
-        const {hasteMap, fileSystem} = await hm.build();
+        const {hasteMap} = await hm.build();
         expect(hasteMap.getModule('Orange', 'ios')).toBeTruthy();
         expect(hasteMap.getModule('Orange', 'android')).toBeTruthy();
         const e = mockEmitters[path.join('/', 'project', 'fruits')];
@@ -2104,12 +2104,12 @@ describe('FileMap', () => {
           },
         ]);
         expect(
-          fileSystem.getModuleName(
+          hasteMap.getModuleNameByPath(
             path.join('/', 'project', 'fruits', 'Orange.ios.js'),
           ),
         ).toBeTruthy();
         expect(
-          fileSystem.getModuleName(
+          hasteMap.getModuleNameByPath(
             path.join('/', 'project', 'fruits', 'Orange.android.js'),
           ),
         ).toBeTruthy();
diff --git a/packages/metro-file-map/src/__tests__/worker-test.js b/packages/metro-file-map/src/__tests__/worker-test.js
index 899dc654af..45375ee386 100644
--- a/packages/metro-file-map/src/__tests__/worker-test.js
+++ b/packages/metro-file-map/src/__tests__/worker-test.js
@@ -13,6 +13,7 @@ import type {WorkerMessage, WorkerMetadata} from '../flow-types';
 import typeof TWorker from '../worker';
 import typeof FS from 'fs';
 
+import {HastePlugin} from '..';
 import {Worker} from '../worker';
 import * as fs from 'fs';
 import * as path from 'path';
@@ -65,13 +66,35 @@ jest.mock('fs', () => {
 });
 
 const defaults: WorkerMessage = {
+  isNodeModules: false,
   computeDependencies: false,
   computeSha1: false,
-  enableHastePackages: false,
   filePath: path.join('/project', 'notexist.js'),
   maybeReturnContent: false,
 };
 
+const defaultHasteConfig = {
+  enableHastePackages: true,
+  failValidationOnConflicts: false,
+  hasteImplModulePath: require.resolve('./haste_impl.js'),
+  platforms: new Set(['ios', 'android']),
+  rootDir: path.normalize('/project'),
+};
+
+function workerWithHaste(
+  message: WorkerMessage,
+  hasteOverrides: Partial<typeof defaultHasteConfig> = {},
+) {
+  return new Worker({
+    plugins: [
+      new HastePlugin({
+        ...defaultHasteConfig,
+        ...hasteOverrides,
+      }).getWorker(),
+    ],
+  }).processFile(message);
+}
+
 describe('worker', () => {
   let worker: (message: WorkerMessage) => Promise<WorkerMetadata>;
 
@@ -84,7 +107,7 @@ describe('worker', () => {
   const defaults: WorkerMessage = {
     computeDependencies: false,
     computeSha1: false,
-    enableHastePackages: false,
+    isNodeModules: false,
     filePath: path.join('/project', 'notexist.js'),
     maybeReturnContent: false,
   };
@@ -98,6 +121,7 @@ describe('worker', () => {
       }),
     ).toEqual({
       dependencies: ['Banana', 'Strawberry'],
+      pluginData: [],
     });
 
     expect(
@@ -108,12 +132,13 @@ describe('worker', () => {
       }),
     ).toEqual({
       dependencies: [],
+      pluginData: [],
     });
   });
 
   test('accepts a custom dependency extractor', async () => {
     expect(
-      new Worker({}).processFile({
+      await worker({
         ...defaults,
         computeDependencies: true,
         dependencyExtractor: path.join(__dirname, 'dependencyExtractor.js'),
@@ -121,62 +146,63 @@ describe('worker', () => {
       }),
     ).toEqual({
       dependencies: ['Banana', 'Strawberry', 'Lime'],
+      pluginData: [],
     });
   });
 
   test('delegates to hasteImplModulePath for getting the id', async () => {
     expect(
-      await worker({
+      await workerWithHaste({
         ...defaults,
         computeDependencies: true,
         filePath: path.join('/project', 'fruits', 'Pear.js'),
-        hasteImplModulePath: require.resolve('./haste_impl.js'),
       }),
     ).toEqual({
       dependencies: ['Banana', 'Strawberry'],
-      id: 'Pear',
+      pluginData: ['Pear'],
     });
 
     expect(
-      await worker({
+      await workerWithHaste({
         ...defaults,
         computeDependencies: true,
         filePath: path.join('/project', 'fruits', 'Strawberry.js'),
-        hasteImplModulePath: require.resolve('./haste_impl.js'),
       }),
     ).toEqual({
       dependencies: [],
-      id: 'Strawberry',
+      pluginData: ['Strawberry'],
     });
   });
 
   test('parses package.json files as haste packages when enableHastePackages=true', async () => {
-    const worker = new Worker({});
     expect(
-      worker.processFile({
-        ...defaults,
-        computeDependencies: true,
-        enableHastePackages: true,
-        filePath: path.join('/project', 'package.json'),
-      }),
+      await workerWithHaste(
+        {
+          ...defaults,
+          computeDependencies: true,
+          filePath: path.join('/project', 'package.json'),
+        },
+        {enableHastePackages: true},
+      ),
     ).toEqual({
       dependencies: undefined,
-      id: 'haste-package',
+      pluginData: ['haste-package'],
     });
   });
 
   test('does not parse package.json files as haste packages when enableHastePackages=false', async () => {
-    const worker = new Worker({});
     expect(
-      worker.processFile({
-        ...defaults,
-        computeDependencies: true,
-        enableHastePackages: false,
-        filePath: path.join('/project', 'package.json'),
-      }),
+      await workerWithHaste(
+        {
+          ...defaults,
+          computeDependencies: true,
+          filePath: path.join('/project', 'package.json'),
+        },
+        {enableHastePackages: false},
+      ),
     ).toEqual({
       dependencies: undefined,
-      id: undefined,
+      pluginData: [null],
     });
   });
 
@@ -203,7 +229,10 @@ describe('worker', () => {
         computeSha1: true,
         filePath: path.join('/project', 'fruits', 'apple.png'),
       }),
-    ).toEqual({sha1: '4caece539b039b16e16206ea2478f8c5ffb2ca05'});
+    ).toEqual({
+      pluginData: [],
+      sha1: '4caece539b039b16e16206ea2478f8c5ffb2ca05',
+    });
 
     expect(
       await worker({
@@ -211,7 +240,7 @@ describe('worker', () => {
         computeSha1: false,
         filePath: path.join('/project', 'fruits', 'Banana.js'),
       }),
-    ).toEqual({sha1: undefined});
+    ).toEqual({pluginData: [], sha1: undefined});
 
     expect(
       await worker({
@@ -219,7 +248,10 @@ describe('worker', () => {
         computeSha1: true,
         filePath: path.join('/project', 'fruits', 'Banana.js'),
       }),
-    ).toEqual({sha1: '7772b628e422e8cf59c526be4bb9f44c0898e3d1'});
+    ).toEqual({
+      pluginData: [],
+      sha1: '7772b628e422e8cf59c526be4bb9f44c0898e3d1',
+    });
 
     expect(
       await worker({
@@ -227,7 +259,10 @@ describe('worker', () => {
         computeSha1: true,
         filePath: path.join('/project', 'fruits', 'Pear.js'),
       }),
-    ).toEqual({sha1: 'c7a7a68a1c8aaf452669dd2ca52ac4a434d25552'});
+    ).toEqual({
+      pluginData: [],
+      sha1: 'c7a7a68a1c8aaf452669dd2ca52ac4a434d25552',
+    });
 
     await expect(() =>
       worker({...defaults, computeSha1: true, filePath: '/i/dont/exist.js'}),
@@ -236,15 +271,14 @@ describe('worker', () => {
 
   test('avoids computing dependencies if not requested and Haste does not need it', async () => {
     expect(
-      await worker({
+      await workerWithHaste({
         ...defaults,
         computeDependencies: false,
         filePath: path.join('/project', 'fruits', 'Pear.js'),
-        hasteImplModulePath: path.resolve(__dirname, 'haste_impl.js'),
       }),
     ).toEqual({
       dependencies: undefined,
-      id: 'Pear',
+      pluginData: ['Pear'],
       sha1: undefined,
     });
 
@@ -255,7 +289,7 @@ describe('worker', () => {
 
   test('returns content if requested and content is read', async () => {
     expect(
-      await worker({
+      await workerWithHaste({
         ...defaults,
         computeSha1: true,
         filePath: path.join('/project', 'fruits', 'Pear.js'),
@@ -263,23 +297,23 @@ describe('worker', () => {
       }),
     ).toEqual({
       content: expect.any(Buffer),
+      pluginData: ['Pear'],
       sha1: 'c7a7a68a1c8aaf452669dd2ca52ac4a434d25552',
     });
   });
 
   test('does not return content if maybeReturnContent but content is not read', async () => {
     expect(
-      await worker({
+      await workerWithHaste({
         ...defaults,
         computeSha1: false,
         filePath: path.join('/project', 'fruits', 'Pear.js'),
-        hasteImplModulePath: path.resolve(__dirname, 'haste_impl.js'),
         maybeReturnContent: true,
       }),
     ).toEqual({
       content: undefined,
       dependencies: undefined,
-      id: 'Pear',
+      pluginData: ['Pear'],
       sha1: undefined,
     });
   });
diff --git a/packages/metro-file-map/src/cache/__tests__/DiskCacheManager-test.js b/packages/metro-file-map/src/cache/__tests__/DiskCacheManager-test.js
index 6fe313dd2c..d03d7ca127 100644
--- a/packages/metro-file-map/src/cache/__tests__/DiskCacheManager-test.js
+++ b/packages/metro-file-map/src/cache/__tests__/DiskCacheManager-test.js
@@ -138,6 +138,9 @@ describe('cacheManager', () => {
       getSerializableSnapshot() {
         return {};
       },
+      getWorker() {
+        return null;
+      },
       onNewOrModifiedFile() {},
       onRemovedFile() {},
       getCacheKey() {
diff --git a/packages/metro-file-map/src/constants.js b/packages/metro-file-map/src/constants.js
index f2c11f4488..78fd7a58a8 100644
--- a/packages/metro-file-map/src/constants.js
+++ b/packages/metro-file-map/src/constants.js
@@ -36,7 +36,7 @@ const constants/*: HType */ = {
   DEPENDENCIES: 3,
   SHA1: 4,
   SYMLINK: 5,
-  ID: 6,
+  PLUGINDATA: 6,
 
   /* module map attributes */
   PATH: 0,
diff --git a/packages/metro-file-map/src/crawlers/__tests__/integration-test.js b/packages/metro-file-map/src/crawlers/__tests__/integration-test.js
index 876ba633fc..775aaaed88 100644
--- a/packages/metro-file-map/src/crawlers/__tests__/integration-test.js
+++ b/packages/metro-file-map/src/crawlers/__tests__/integration-test.js
@@ -84,18 +84,26 @@ const CASES = [
   [
     true,
     new Map([
-      ['foo.js', [expect.any(Number), 245, 0, '', null, 0, '']],
+      ['foo.js', [expect.any(Number), 245, 0, '', null, 0, null]],
       [
         join('directory', 'bar.js'),
-        [expect.any(Number), 245, 0, '', null, 0, ''],
+        [expect.any(Number), 245, 0, '', null, 0, null],
       ],
       [
         'link-to-directory',
-        [expect.any(Number), 9, 0, '', null, expect.oneOf(1, 'directory'), ''],
+        [
+          expect.any(Number),
+          9,
+          0,
+          '',
+          null,
+          expect.oneOf(1, 'directory'),
+          null,
+        ],
       ],
       [
         'link-to-foo.js',
-        [expect.any(Number), 6, 0, '', null, expect.oneOf(1, 'foo.js'), ''],
+        [expect.any(Number), 6, 0, '', null, expect.oneOf(1, 'foo.js'), null],
       ],
     ]),
   ],
@@ -104,9 +112,9 @@ const CASES = [
     new Map([
       [
         join('directory', 'bar.js'),
-        [expect.any(Number), 245, 0, '', null, 0, ''],
+        [expect.any(Number), 245, 0, '', null, 0, null],
       ],
-      ['foo.js', [expect.any(Number), 245, 0, '', null, 0, '']],
+      ['foo.js', [expect.any(Number), 245, 0, '', null, 0, null]],
     ]),
   ],
 ];
@@ -126,7 +134,9 @@ describe.each(Object.keys(CRAWLERS))(
           previousState: {
             fileSystem: new TreeFS({
               rootDir: FIXTURES_DIR,
-              files: new Map([['removed.js', [123, 234, 0, '', null, 0, '']]]),
+              files: new Map([
+                ['removed.js', [123, 234, 0, '', null, 0, null]],
+              ]),
               processFile: () => {
                 throw new Error('Not implemented');
               },
diff --git a/packages/metro-file-map/src/crawlers/__tests__/node-test.js b/packages/metro-file-map/src/crawlers/__tests__/node-test.js
index 1bc720543b..6fbba2fa70 100644
--- a/packages/metro-file-map/src/crawlers/__tests__/node-test.js
+++ b/packages/metro-file-map/src/crawlers/__tests__/node-test.js
@@ -185,9 +185,9 @@ describe('node crawler', () => {
 
     expect(changedFiles).toEqual(
       createMap({
-        'fruits/strawberry.js': [32, 42, 0, '', null, 0, ''],
-        'fruits/tomato.js': [33, 42, 0, '', null, 0, ''],
-        'vegetables/melon.json': [34, 42, 0, '', null, 0, ''],
+        'fruits/strawberry.js': [32, 42, 0, '', null, 0, null],
+        'fruits/tomato.js': [33, 42, 0, '', null, 0, null],
+        'vegetables/melon.json': [34, 42, 0, '', null, 0, null],
       }),
     );
 
@@ -198,9 +198,9 @@ describe('node crawler', () => {
     nodeCrawl = require('../node').default;
 
     // In this test sample, strawberry is changed and tomato is unchanged
-    const tomato = [33, 42, 1, '', null, 0, ''];
+    const tomato = [33, 42, 1, '', null, 0, null];
     const files = createMap({
-      'fruits/strawberry.js': [30, 40, 1, '', null, 0, ''],
+      'fruits/strawberry.js': [30, 40, 1, '', null, 0, null],
       'fruits/tomato.js': tomato,
     });
 
@@ -215,7 +215,7 @@ describe('node crawler', () => {
     // Tomato is not included because it is unchanged
     expect(changedFiles).toEqual(
       createMap({
-        'fruits/strawberry.js': [32, 42, 0, '', null, 0, ''],
+        'fruits/strawberry.js': [32, 42, 0, '', null, 0, null],
       }),
     );
 
@@ -228,9 +228,9 @@ describe('node crawler', () => {
     // In this test sample, previouslyExisted was present before and will not be
     // when crawling this directory.
     const files = createMap({
-      'fruits/previouslyExisted.js': [30, 40, 1, '', null, 0, ''],
-      'fruits/strawberry.js': [33, 42, 0, '', null, 0, ''],
-      'fruits/tomato.js': [32, 42, 0, '', null, 0, ''],
+      'fruits/previouslyExisted.js': [30, 40, 1, '', null, 0, null],
+      'fruits/strawberry.js': [33, 42, 0, '', null, 0, null],
+      'fruits/tomato.js': [32, 42, 0, '', null, 0, null],
     });
 
     const {changedFiles, removedFiles} = await nodeCrawl({
@@ -243,8 +243,8 @@ describe('node crawler', () => {
 
     expect(changedFiles).toEqual(
       createMap({
-        'fruits/strawberry.js': [32, 42, 0, '', null, 0, ''],
-        'fruits/tomato.js': [33, 42, 0, '', null, 0, ''],
+        'fruits/strawberry.js': [32, 42, 0, '', null, 0, null],
+        'fruits/tomato.js': [33, 42, 0, '', null, 0, null],
       }),
     );
     expect(removedFiles).toEqual(new Set(['fruits/previouslyExisted.js']));
@@ -272,8 +272,8 @@ describe('node crawler', () => {
     );
     expect(changedFiles).toEqual(
       createMap({
-        'fruits/directory/strawberry.js': [33, 42, 0, '', null, 0, ''],
-        'fruits/tomato.js': [32, 42, 0, '', null, 0, ''],
+        'fruits/directory/strawberry.js': [33, 42, 0, '', null, 0, null],
+        'fruits/tomato.js': [32, 42, 0, '', null, 0, null],
       }),
     );
     expect(removedFiles).toEqual(new Set());
@@ -297,8 +297,8 @@ describe('node crawler', () => {
 
     expect(changedFiles).toEqual(
       createMap({
-        'fruits/directory/strawberry.js': [33, 42, 0, '', null, 0, ''],
-        'fruits/tomato.js': [32, 42, 0, '', null, 0, ''],
+        'fruits/directory/strawberry.js': [33, 42, 0, '', null, 0, null],
+        'fruits/tomato.js': [32, 42, 0, '', null, 0, null],
       }),
     );
     expect(removedFiles).toEqual(new Set());
@@ -321,8 +321,8 @@ describe('node crawler', () => {
     expect(childProcess.spawn).toHaveBeenCalledTimes(0);
     expect(changedFiles).toEqual(
       createMap({
-        'fruits/directory/strawberry.js': [33, 42, 0, '', null, 0, ''],
-        'fruits/tomato.js': [32, 42, 0, '', null, 0, ''],
+        'fruits/directory/strawberry.js': [33, 42, 0, '', null, 0, null],
+        'fruits/tomato.js': [32, 42, 0, '', null, 0, null],
       }),
     );
     expect(removedFiles).toEqual(new Set());
@@ -386,8 +386,8 @@ describe('node crawler', () => {
 
     expect(changedFiles).toEqual(
       createMap({
-        'fruits/directory/strawberry.js': [33, 42, 0, '', null, 0, ''],
-        'fruits/tomato.js': [32, 42, 0, '', null, 0, ''],
+        'fruits/directory/strawberry.js': [33, 42, 0, '', null, 0, null],
+        'fruits/tomato.js': [32, 42, 0, '', null, 0, null],
       }),
     );
     expect(removedFiles).toEqual(new Set());
diff --git a/packages/metro-file-map/src/crawlers/__tests__/watchman-test.js b/packages/metro-file-map/src/crawlers/__tests__/watchman-test.js
index 2d971458cd..ee4b25363f 100644
--- a/packages/metro-file-map/src/crawlers/__tests__/watchman-test.js
+++ b/packages/metro-file-map/src/crawlers/__tests__/watchman-test.js
@@ -118,9 +118,9 @@ describe('watchman watch', () => {
     };
 
     mockFiles = createMap({
-      [MELON_RELATIVE]: [33, 43, 0, '', null, 0, ''],
-      [STRAWBERRY_RELATIVE]: [30, 40, 0, '', null, 0, ''],
-      [TOMATO_RELATIVE]: [31, 41, 0, '', null, 0, ''],
+      [MELON_RELATIVE]: [33, 43, 0, '', null, 0, null],
+      [STRAWBERRY_RELATIVE]: [30, 40, 0, '', null, 0, null],
+      [TOMATO_RELATIVE]: [31, 41, 0, '', null, 0, null],
     });
   });
 
@@ -223,7 +223,7 @@ describe('watchman watch', () => {
 
     expect(changedFiles).toEqual(
       createMap({
-        [KIWI_RELATIVE]: [42, 40, 0, '', null, 0, ''],
+        [KIWI_RELATIVE]: [42, 40, 0, '', null, 0, null],
       }),
     );
 
@@ -296,7 +296,7 @@ describe('watchman watch', () => {
     // banana is not included because it is unchanged
     expect(changedFiles).toEqual(
       createMap({
-        [KIWI_RELATIVE]: [42, 52, 0, '', null, 0, ''],
+        [KIWI_RELATIVE]: [42, 52, 0, '', null, 0, null],
         [TOMATO_RELATIVE]: [76, 41, 1, '', mockTomatoSha1, 0, 'Tomato'],
       }),
     );
@@ -373,7 +373,7 @@ describe('watchman watch', () => {
     // Melon is not included because it is unchanged.
     expect(changedFiles).toEqual(
       createMap({
-        [KIWI_RELATIVE]: [42, 52, 0, '', null, 0, ''],
+        [KIWI_RELATIVE]: [42, 52, 0, '', null, 0, null],
       }),
     );
 
@@ -542,7 +542,7 @@ describe('watchman watch', () => {
 
     expect(changedFiles).toEqual(
       createMap({
-        [KIWI_RELATIVE]: [42, 40, 0, '', null, 0, ''],
+        [KIWI_RELATIVE]: [42, 40, 0, '', null, 0, null],
       }),
     );
 
diff --git a/packages/metro-file-map/src/crawlers/node/index.js b/packages/metro-file-map/src/crawlers/node/index.js
index a21fb02b1e..075a87516c 100644
--- a/packages/metro-file-map/src/crawlers/node/index.js
+++ b/packages/metro-file-map/src/crawlers/node/index.js
@@ -82,7 +82,7 @@ function find(
                   '',
                   null,
                   stat.isSymbolicLink() ? 1 : 0,
-                  '',
+                  null,
                 ]);
               }
             }
@@ -160,7 +160,7 @@ function findNative(
               '',
               null,
               stat.isSymbolicLink() ? 1 : 0,
-              '',
+              null,
             ]);
           }
           if (--count === 0) {
diff --git a/packages/metro-file-map/src/crawlers/watchman/index.js b/packages/metro-file-map/src/crawlers/watchman/index.js
index 5a3d15868e..68baacc658 100644
--- a/packages/metro-file-map/src/crawlers/watchman/index.js
+++ b/packages/metro-file-map/src/crawlers/watchman/index.js
@@ -339,7 +339,7 @@ export default async function watchmanCrawl({
           '',
           sha1hex ?? null,
           symlinkInfo,
-          '',
+          null,
         ];
 
         // If watchman is fresh, the removed files map starts with all files
diff --git a/packages/metro-file-map/src/flow-types.js b/packages/metro-file-map/src/flow-types.js
index 228b43de79..cbf2253425 100644
--- a/packages/metro-file-map/src/flow-types.js
+++ b/packages/metro-file-map/src/flow-types.js
@@ -165,45 +165,68 @@ export type EventsQueue = Array<{
   type: string,
 }>;
 
-export type FileMapDelta = $ReadOnly<{
-  removed: Iterable<[CanonicalPath, FileMetadata]>,
-  addedOrModified: Iterable<[CanonicalPath, FileMetadata]>,
+export type FileMapDelta<T = null | void> = $ReadOnly<{
+  removed: Iterable<[CanonicalPath, T]>,
+  addedOrModified: Iterable<[CanonicalPath, T]>,
 }>;
 
-interface FileSystemState {
-  metadataIterator(
-    opts: $ReadOnly<{
-      includeNodeModules: boolean,
-      includeSymlinks: boolean,
+export type FileMapPluginInitOptions<
+  SerializableState,
+  PerFileData = null | void,
+> = $ReadOnly<{
+  files: $ReadOnly<{
+    metadataIterator(
+      opts: $ReadOnly<{
+        includeNodeModules: boolean,
+        includeSymlinks: boolean,
+      }>,
+    ): Iterable<{
+      baseName: string,
+      canonicalPath: string,
+      data: PerFileData,
     }>,
-  ): Iterable<{
-    baseName: string,
-    canonicalPath: string,
-    metadata: FileMetadata,
-  }>;
-}
-
-export type FileMapPluginInitOptions<SerializableState> = $ReadOnly<{
-  files: FileSystemState,
+    getFilePluginData(mixedPath: string): ?PerFileData,
+  }>,
   pluginState: ?SerializableState,
 }>;
 
-type V8Serializable = interface {};
+export type FileMapPluginWorker = $ReadOnly<{
+  workerModulePath: string,
+  workerSetupArgs: JsonData,
+}>;
 
-export interface FileMapPlugin<SerializableState = V8Serializable> {
+export type V8Serializable =
+  | string
+  | number
+  | boolean
+  | null
+  | $ReadOnlyArray<V8Serializable>
+  | $ReadOnlySet<V8Serializable>
+  | $ReadOnlyMap<string, V8Serializable>
+  | {[key: string]: V8Serializable};
+
+export interface FileMapPlugin<
+  SerializableState = V8Serializable,
+  PerFileData = null | void,
+> {
   +name: string;
   initialize(
-    initOptions: FileMapPluginInitOptions<SerializableState>,
+    initOptions: FileMapPluginInitOptions<SerializableState, PerFileData>,
   ): Promise<void>;
   assertValid(): void;
-  bulkUpdate(delta: FileMapDelta): Promise<void>;
+  bulkUpdate(delta: FileMapDelta<?PerFileData>): Promise<void>;
   getSerializableSnapshot(): SerializableState;
-  onRemovedFile(relativeFilePath: string, fileMetadata: FileMetadata): void;
-  onNewOrModifiedFile(
-    relativeFilePath: string,
-    fileMetadata: FileMetadata,
-  ): void;
+  onRemovedFile(relativeFilePath: string, pluginData: PerFileData): void;
+  onNewOrModifiedFile(relativeFilePath: string, pluginData: PerFileData): void;
   getCacheKey(): string;
+  getWorker(): ?FileMapPluginWorker;
+}
+
+export interface MetadataWorker {
+  processFile(
+    WorkerMessage,
+    $ReadOnly<{getContent: () => Buffer}>,
+  ): V8Serializable;
 }
 
 export type HType = {
@@ -213,7 +236,7 @@ export type HType = {
   DEPENDENCIES: 3,
   SHA1: 4,
   SYMLINK: 5,
-  ID: 6,
+  PLUGINDATA: number,
   PATH: 0,
   TYPE: 1,
   MODULE: 0,
@@ -236,7 +259,8 @@ export type FileMetadata = [
   /* dependencies */ string,
   /* sha1 */ ?string,
   /* symlink */ 0 | 1 | string, // string specifies target, if known
-  /* id */ string,
+  /* plugindata */
+  ...
 ];
 
 export type FileStats = $ReadOnly<{
@@ -253,7 +277,6 @@ export interface FileSystem {
     changedFiles: FileData,
     removedFiles: Set<string>,
   };
-  getModuleName(file: Path): ?string;
   getSerializableSnapshot(): CacheData['fileSystemData'];
   getSha1(file: Path): ?string;
   getOrComputeSha1(file: Path): Promise<?{sha1: string, content?: Buffer}>;
@@ -324,6 +347,14 @@ export interface FileSystem {
 
 export type Glob = string;
 
+export type JsonData =
+  | string
+  | number
+  | boolean
+  | null
+  | Array<JsonData>
+  | {[key: string]: JsonData};
+
 export type LookupResult =
   | {
       // The node is missing from the FileSystem implementation (note this
@@ -366,6 +397,8 @@ export interface HasteMap {
     type?: ?HTypeValue,
   ): ?Path;
 
+  getModuleNameByPath(file: Path): ?string;
+
   getPackage(
     name: string,
     platform: ?string,
@@ -460,17 +493,18 @@ export type WorkerMessage = $ReadOnly<{
   computeDependencies: boolean,
   computeSha1: boolean,
   dependencyExtractor?: ?string,
-  enableHastePackages: boolean,
+  isNodeModules: boolean,
   filePath: string,
-  hasteImplModulePath?: ?string,
   maybeReturnContent: boolean,
 }>;
 
 export type WorkerMetadata = $ReadOnly<{
   dependencies?: ?$ReadOnlyArray<string>,
-  id?: ?string,
   sha1?: ?string,
   content?: ?Buffer,
+  pluginData?: $ReadOnlyArray<V8Serializable>,
 }>;
 
-export type WorkerSetupArgs = $ReadOnly<{}>;
+export type WorkerSetupArgs = $ReadOnly<{
+  plugins?: $ReadOnlyArray<FileMapPluginWorker>,
+}>;
diff --git a/packages/metro-file-map/src/index.js b/packages/metro-file-map/src/index.js
index 7430775a89..556b2ac34f 100644
--- a/packages/metro-file-map/src/index.js
+++ b/packages/metro-file-map/src/index.js
@@ -123,6 +123,13 @@ type InternalOptions = $ReadOnly<{
   watchmanDeferStates: $ReadOnlyArray<string>,
 }>;
 
+// $FlowFixMe[unclear-type] Plugin types cannot be known statically
+type AnyFileMapPlugin = FileMapPlugin<any, any>;
+type IndexedPlugin = $ReadOnly<{
+  plugin: AnyFileMapPlugin,
+  dataIdx: ?number,
+}>;
+
 export {DiskCacheManager} from './cache/DiskCacheManager';
 export {DuplicateHasteCandidatesError} from './plugins/haste/DuplicateHasteCandidatesError';
 export {HasteConflictsError} from './plugins/haste/HasteConflictsError';
@@ -143,7 +150,7 @@ export type {
 // This should be bumped whenever a code change to `metro-file-map` itself
 // would cause a change to the cache data structure and/or content (for a given
 // filesystem state and build parameters).
-const CACHE_BREAKER = '10';
+const CACHE_BREAKER = '11';
 
 const CHANGE_INTERVAL = 30;
 
@@ -252,7 +259,7 @@ export default class FileMap extends EventEmitter {
 
   #hastePlugin: HastePlugin;
   #mockPlugin: ?MockPlugin = null;
-  #plugins: $ReadOnlyArray<FileMapPlugin<>>;
+  #plugins: $ReadOnlyArray<IndexedPlugin>;
 
   static create(options: InputOptions): FileMap {
     return new FileMap(options);
@@ -293,13 +300,14 @@ export default class FileMap extends EventEmitter {
     this.#hastePlugin = new HastePlugin({
       console: this._console,
       enableHastePackages,
+      hasteImplModulePath: options.hasteImplModulePath,
       perfLogger: this._startupPerfLogger,
       platforms: new Set(options.platforms),
       rootDir: options.rootDir,
       failValidationOnConflicts: throwOnModuleCollision,
     });
 
-    const plugins: Array<FileMapPlugin<$FlowFixMe>> = [this.#hastePlugin];
+    const plugins: Array<AnyFileMapPlugin> = [this.#hastePlugin];
 
     if (options.mocksPattern != null && options.mocksPattern !== '') {
       this.#mockPlugin = new MockPlugin({
@@ -311,7 +319,11 @@ export default class FileMap extends EventEmitter {
       plugins.push(this.#mockPlugin);
     }
 
-    this.#plugins = plugins;
+    let dataSlot: number = H.PLUGINDATA;
+    this.#plugins = plugins.map(plugin => ({
+      plugin,
+      dataIdx: isDataPlugin(plugin) ? dataSlot++ : null,
+    }));
 
     const buildParameters: BuildParameters = {
       computeDependencies:
@@ -353,12 +365,11 @@ export default class FileMap extends EventEmitter {
 
     this._fileProcessor = new FileProcessor({
       dependencyExtractor: buildParameters.dependencyExtractor,
-      enableHastePackages: buildParameters.enableHastePackages,
       enableWorkerThreads: options.enableWorkerThreads ?? false,
-      hasteImplModulePath: buildParameters.hasteImplModulePath,
       maxFilesPerWorker: options.maxFilesPerWorker,
       maxWorkers: options.maxWorkers,
       perfLogger: this._startupPerfLogger,
+      pluginWorkers: plugins.map(plugin => plugin.getWorker()).filter(Boolean),
     });
 
     this._buildPromise = null;
@@ -428,9 +439,28 @@ export default class FileMap extends EventEmitter {
             clocks: initialData?.clocks ?? new Map(),
           }),
           Promise.all(
-            plugins.map(plugin =>
+            plugins.map(({plugin, dataIdx}) =>
               plugin.initialize({
-                files: fileSystem,
+                files: {
+                  getFilePluginData:
+                    dataIdx != null
+                      ? (filePath: string) =>
+                          fileSystem.getFileMetadata(filePath)?.[dataIdx]
+                      : () => {
+                          throw new Error(
+                            'Plugin does not store file metadata',
+                          );
+                        },
+                  metadataIterator: opts =>
+                    mapIterator(
+                      fileSystem.metadataIterator(opts),
+                      ({baseName, canonicalPath, metadata}) => ({
+                        baseName,
+                        canonicalPath,
+                        data: dataIdx != null ? metadata[dataIdx] : null,
+                      }),
+                    ),
+                },
                 pluginState: initialData?.plugins.get(plugin.name),
               }),
             ),
@@ -441,7 +471,7 @@ export default class FileMap extends EventEmitter {
         await this._applyFileDelta(fileSystem, plugins, fileDelta);
 
         // Validate the mock and Haste maps before persisting them.
-        plugins.forEach(plugin => plugin.assertValid());
+        plugins.forEach(({plugin}) => plugin.assertValid());
 
         const watchmanClocks = new Map(fileDelta.clocks ?? []);
         await this._takeSnapshotAndPersist(
@@ -565,7 +595,7 @@ export default class FileMap extends EventEmitter {
 
   async _applyFileDelta(
     fileSystem: MutableFileSystem,
-    plugins: $ReadOnlyArray<FileMapPlugin<>>,
+    plugins: $ReadOnlyArray<IndexedPlugin>,
     delta: $ReadOnly<{
       changedFiles: FileData,
       removedFiles: $ReadOnlySet<CanonicalPath>,
@@ -695,13 +725,18 @@ export default class FileMap extends EventEmitter {
     this._startupPerfLogger?.point('applyFileDelta_add_end');
 
     this._startupPerfLogger?.point('applyFileDelta_updatePlugins_start');
+
     await Promise.all([
-      plugins.map(plugin =>
-        plugin.bulkUpdate({
-          addedOrModified: changedFiles,
-          removed,
-        }),
-      ),
+      plugins.map(({plugin, dataIdx}) => {
+        const mapFn: ([CanonicalPath, FileMetadata]) => [CanonicalPath, mixed] =
+          dataIdx != null
+            ? ([relativePath, fileData]) => [relativePath, fileData[dataIdx]]
+            : ([relativePath, fileData]) => [relativePath, null];
+        return plugin.bulkUpdate({
+          addedOrModified: mapIterator(changedFiles.entries(), mapFn),
+          removed: mapIterator(removed.values(), mapFn),
+        });
+      }),
     ]);
     this._startupPerfLogger?.point('applyFileDelta_updatePlugins_end');
     this._startupPerfLogger?.point('applyFileDelta_end');
@@ -713,7 +748,7 @@ export default class FileMap extends EventEmitter {
   async _takeSnapshotAndPersist(
     fileSystem: FileSystem,
     clocks: WatchmanClocks,
-    plugins: $ReadOnlyArray<FileMapPlugin<>>,
+    plugins: $ReadOnlyArray<IndexedPlugin>,
     changed: FileData,
     removed: Set<CanonicalPath>,
   ) {
@@ -723,7 +758,7 @@ export default class FileMap extends EventEmitter {
         fileSystemData: fileSystem.getSerializableSnapshot(),
         clocks: new Map(clocks),
         plugins: new Map(
-          plugins.map(plugin => [
+          plugins.map(({plugin}) => [
             plugin.name,
             plugin.getSerializableSnapshot(),
           ]),
@@ -758,7 +793,7 @@ export default class FileMap extends EventEmitter {
   async _watch(
     fileSystem: MutableFileSystem,
     clocks: WatchmanClocks,
-    plugins: $ReadOnlyArray<FileMapPlugin<>>,
+    plugins: $ReadOnlyArray<IndexedPlugin>,
   ): Promise<void> {
     this._startupPerfLogger?.point('watch_start');
     if (!this._options.watch) {
@@ -913,7 +948,7 @@ export default class FileMap extends EventEmitter {
               '',
               null,
               change.metadata.type === 'l' ? 1 : 0,
-              '',
+              null,
             ];
 
             try {
@@ -932,8 +967,13 @@ export default class FileMap extends EventEmitter {
               }
               fileSystem.addOrModify(relativeFilePath, fileMetadata);
               this._updateClock(clocks, change.clock);
-              plugins.forEach(plugin =>
-                plugin.onNewOrModifiedFile(relativeFilePath, fileMetadata),
+              plugins.forEach(({plugin, dataIdx}) =>
+                dataIdx != null
+                  ? plugin.onNewOrModifiedFile(
+                      relativeFilePath,
+                      fileMetadata[dataIdx],
+                    )
+                  : plugin.onNewOrModifiedFile(relativeFilePath),
               );
               enqueueEvent(change.metadata);
             } catch (e) {
@@ -957,8 +997,10 @@ export default class FileMap extends EventEmitter {
             // exists in the file map and remove should always return metadata.
             const metadata = nullthrows(fileSystem.remove(relativeFilePath));
             this._updateClock(clocks, change.clock);
-            plugins.forEach(plugin =>
-              plugin.onRemovedFile(relativeFilePath, metadata),
+            plugins.forEach(({plugin, dataIdx}) =>
+              dataIdx != null
+                ? plugin.onRemovedFile(relativeFilePath, metadata[dataIdx])
+                : plugin.onRemovedFile(relativeFilePath),
             );
 
             enqueueEvent({
@@ -1074,3 +1116,19 @@ export default class FileMap extends EventEmitter {
 
   static H: HType = H;
 }
+
+// TODO: Replace with it.map() from Node 22+
+const mapIterator: <T, S>(Iterator<T>, (T) => S) => Iterable<S> = (it, fn) =>
+  'map' in it
+    ? it.map(fn)
+    : (function* mapped() {
+        for (const item of it) {
+          yield fn(item);
+        }
+      })();
+
+function isDataPlugin(plugin: AnyFileMapPlugin): boolean {
+  // TODO: Allow plugins to declare whether they store per-file data,
+  // remove this special-casing of HastePlugin.
+  return plugin instanceof HastePlugin;
+}
diff --git a/packages/metro-file-map/src/lib/FileProcessor.js b/packages/metro-file-map/src/lib/FileProcessor.js
index d22d4e9cd5..9ea252a118 100644
--- a/packages/metro-file-map/src/lib/FileProcessor.js
+++ b/packages/metro-file-map/src/lib/FileProcessor.js
@@ -10,6 +10,7 @@
  */
 
 import type {
+  FileMapPluginWorker,
   FileMetadata,
   PerfLogger,
   WorkerMessage,
@@ -68,21 +69,20 @@ export class FileProcessor {
   constructor(
     opts: $ReadOnly<{
       dependencyExtractor: ?string,
-      enableHastePackages: boolean,
       enableWorkerThreads: boolean,
-      hasteImplModulePath: ?string,
       maxFilesPerWorker?: ?number,
       maxWorkers: number,
+      pluginWorkers: ?$ReadOnlyArray<FileMapPluginWorker>,
       perfLogger: ?PerfLogger,
     }>,
   ) {
     this.#dependencyExtractor = opts.dependencyExtractor;
-    this.#enableHastePackages = opts.enableHastePackages;
     this.#enableWorkerThreads = opts.enableWorkerThreads;
-    this.#hasteImplModulePath = opts.hasteImplModulePath;
     this.#maxFilesPerWorker = opts.maxFilesPerWorker ?? MAX_FILES_PER_WORKER;
     this.#maxWorkers = opts.maxWorkers;
-    this.#workerArgs = {};
+    this.#workerArgs = {
+      plugins: [...(opts.pluginWorkers ?? [])],
+    };
     this.#inBandWorker = new Worker(this.#workerArgs);
     this.#perfLogger = opts.perfLogger;
   }
@@ -153,7 +153,7 @@ export class FileProcessor {
     req: ProcessFileRequest,
   ): ?WorkerMessage {
     const computeSha1 = req.computeSha1 && fileMetadata[H.SHA1] == null;
-
+    const isNodeModules = absolutePath.includes(NODE_MODULES);
     const {computeDependencies, maybeReturnContent} = req;
 
     // Use a cheaper worker configuration for node_modules files, because we
@@ -168,9 +168,8 @@ export class FileProcessor {
           computeDependencies: false,
           computeSha1: true,
           dependencyExtractor: null,
-          enableHastePackages: false,
+          isNodeModules,
           filePath: absolutePath,
-          hasteImplModulePath: null,
           maybeReturnContent,
         };
       }
@@ -181,9 +180,8 @@ export class FileProcessor {
       computeDependencies,
       computeSha1,
       dependencyExtractor: this.#dependencyExtractor,
-      enableHastePackages: this.#enableHastePackages,
+      isNodeModules,
       filePath: absolutePath,
-      hasteImplModulePath: this.#hasteImplModulePath,
       maybeReturnContent,
     };
   }
@@ -235,11 +233,13 @@ function processWorkerReply(
   fileMetadata: FileMetadata,
 ) {
   fileMetadata[H.VISITED] = 1;
-
-  const metadataId = metadata.id;
-
-  if (metadataId != null) {
-    fileMetadata[H.ID] = metadataId;
+  if (metadata.pluginData) {
+    // $FlowFixMe[incompatible-type] - treat inexact tuple as array to set tail entries
+    (fileMetadata as Array<mixed>).splice(
+      H.PLUGINDATA,
+      metadata.pluginData.length,
+      ...metadata.pluginData,
+    );
   }
 
   fileMetadata[H.DEPENDENCIES] = metadata.dependencies
diff --git a/packages/metro-file-map/src/lib/TreeFS.js b/packages/metro-file-map/src/lib/TreeFS.js
index 76a653e6b7..8c6507d715 100644
--- a/packages/metro-file-map/src/lib/TreeFS.js
+++ b/packages/metro-file-map/src/lib/TreeFS.js
@@ -134,9 +134,8 @@ export default class TreeFS implements MutableFileSystem {
     return tfs;
   }
 
-  getModuleName(mixedPath: Path): ?string {
-    const fileMetadata = this._getFileData(mixedPath);
-    return (fileMetadata && fileMetadata[H.ID]) ?? null;
+  getFileMetadata(mixedPath: Path): ?FileMetadata {
+    return this._getFileData(mixedPath, {followLeaf: true});
   }
 
   getSize(mixedPath: Path): ?number {
@@ -1006,7 +1005,7 @@ export default class TreeFS implements MutableFileSystem {
       includeSymlinks: boolean,
       includeNodeModules: boolean,
     }>,
-  ): Iterable<{
+  ): Iterator<{
     baseName: string,
     canonicalPath: string,
     metadata: FileMetadata,
diff --git a/packages/metro-file-map/src/lib/__tests__/FileProcessor-test.js b/packages/metro-file-map/src/lib/__tests__/FileProcessor-test.js
index 16c66bcc45..3d632da108 100644
--- a/packages/metro-file-map/src/lib/__tests__/FileProcessor-test.js
+++ b/packages/metro-file-map/src/lib/__tests__/FileProcessor-test.js
@@ -10,6 +10,7 @@
  */
 
 import type {
+  FileMapPluginWorker,
   FileMetadata,
   WorkerMessage,
   WorkerMetadata,
@@ -25,11 +26,10 @@ const mockWorkerFn = jest.fn().mockReturnValue({});
 
 const defaultOptions = {
   dependencyExtractor: null,
-  enableHastePackages: false,
   enableWorkerThreads: true,
-  hasteImplModulePath: null,
   maxWorkers: 5,
   perfLogger: null,
+  pluginWorkers: [] as $ReadOnlyArray<FileMapPluginWorker>,
 };
 
 describe('processBatch', () => {
@@ -133,6 +133,6 @@ function getNMockFiles(numFiles: number): Array<[string, FileMetadata]> {
     .fill(null)
     .map((_, i) => [
       `file${i}.js`,
-      [123, 234, 0, '', null, 0, ''] as FileMetadata,
+      [123, 234, 0, '', null, 0, null] as FileMetadata,
     ]);
 }
diff --git a/packages/metro-file-map/src/lib/__tests__/TreeFS-test.js b/packages/metro-file-map/src/lib/__tests__/TreeFS-test.js
index de81077a7a..49734decdc 100644
--- a/packages/metro-file-map/src/lib/__tests__/TreeFS-test.js
+++ b/packages/metro-file-map/src/lib/__tests__/TreeFS-test.js
@@ -36,18 +36,18 @@ describe.each([['win32'], ['posix']])('TreeFS on %s', platform => {
       rootDir: p('/project'),
       files: new Map<CanonicalPath, FileMetadata>([
         [p('foo/another.js'), [123, 2, 0, '', '', 0, 'another']],
-        [p('foo/owndir'), [0, 0, 0, '', '', '.', '']],
-        [p('foo/link-to-bar.js'), [0, 0, 0, '', '', p('../bar.js'), '']],
-        [p('foo/link-to-another.js'), [0, 0, 0, '', '', p('another.js'), '']],
-        [p('../outside/external.js'), [0, 0, 0, '', '', 0, '']],
+        [p('foo/owndir'), [0, 0, 0, '', '', '.', null]],
+        [p('foo/link-to-bar.js'), [0, 0, 0, '', '', p('../bar.js'), null]],
+        [p('foo/link-to-another.js'), [0, 0, 0, '', '', p('another.js'), null]],
+        [p('../outside/external.js'), [0, 0, 0, '', '', 0, null]],
         [p('bar.js'), [234, 3, 0, '', '', 0, 'bar']],
-        [p('link-to-foo'), [456, 0, 0, '', '', p('./../project/foo'), '']],
-        [p('abs-link-out'), [456, 0, 0, '', '', p('/outside/./baz/..'), '']],
-        [p('root'), [0, 0, 0, '', '', '..', '']],
-        [p('link-to-nowhere'), [123, 0, 0, '', '', p('./nowhere'), '']],
-        [p('link-to-self'), [123, 0, 0, '', '', p('./link-to-self'), '']],
-        [p('link-cycle-1'), [123, 0, 0, '', '', p('./link-cycle-2'), '']],
-        [p('link-cycle-2'), [123, 0, 0, '', '', p('./link-cycle-1'), '']],
+        [p('link-to-foo'), [456, 0, 0, '', '', p('./../project/foo'), null]],
+        [p('abs-link-out'), [456, 0, 0, '', '', p('/outside/./baz/..'), null]],
+        [p('root'), [0, 0, 0, '', '', '..', null]],
+        [p('link-to-nowhere'), [123, 0, 0, '', '', p('./nowhere'), null]],
+        [p('link-to-self'), [123, 0, 0, '', '', p('./link-to-self'), null]],
+        [p('link-cycle-1'), [123, 0, 0, '', '', p('./link-cycle-2'), null]],
+        [p('link-cycle-2'), [123, 0, 0, '', '', p('./link-cycle-1'), null]],
         [p('node_modules/pkg/a.js'), [123, 0, 0, '', '', 0, 'a']],
         [p('node_modules/pkg/package.json'), [123, 0, 0, '', '', 0, 'pkg']],
       ]),
@@ -187,8 +187,8 @@ describe.each([['win32'], ['posix']])('TreeFS on %s', platform => {
       const tfs = new TreeFS({
         rootDir: p('/deep/project/root'),
         files: new Map<CanonicalPath, FileMetadata>([
-          [p('foo/index.js'), [123, 0, 0, '', '', 0, '']],
-          [p('link-up'), [123, 0, 0, '', '', p('..'), '']],
+          [p('foo/index.js'), [123, 0, 0, '', '', 0, null]],
+          [p('link-up'), [123, 0, 0, '', '', p('..'), null]],
         ]),
         processFile: () => {
           throw new Error('Not implemented');
@@ -215,7 +215,7 @@ describe.each([['win32'], ['posix']])('TreeFS on %s', platform => {
 
   describe('symlinks to an ancestor of the project root', () => {
     beforeEach(() => {
-      tfs.addOrModify(p('foo/link-up-2'), [0, 0, 0, '', '', p('../..'), '']);
+      tfs.addOrModify(p('foo/link-up-2'), [0, 0, 0, '', '', p('../..'), null]);
     });
 
     test.each([
@@ -269,23 +269,23 @@ describe.each([['win32'], ['posix']])('TreeFS on %s', platform => {
   describe('getDifference', () => {
     test('returns changed (inc. new) and removed files in given FileData', () => {
       const newFiles: FileData = new Map<CanonicalPath, FileMetadata>([
-        [p('new-file'), [789, 0, 0, '', '', 0, '']],
-        [p('link-to-foo'), [456, 0, 0, '', '', p('./foo'), '']],
+        [p('new-file'), [789, 0, 0, '', '', 0, null]],
+        [p('link-to-foo'), [456, 0, 0, '', '', p('./foo'), null]],
         // Different modified time, expect new mtime in changedFiles
-        [p('foo/another.js'), [124, 0, 0, '', '', 0, '']],
-        [p('link-cycle-1'), [123, 0, 0, '', '', p('./link-cycle-2'), '']],
-        [p('link-cycle-2'), [123, 0, 0, '', '', p('./link-cycle-1'), '']],
+        [p('foo/another.js'), [124, 0, 0, '', '', 0, null]],
+        [p('link-cycle-1'), [123, 0, 0, '', '', p('./link-cycle-2'), null]],
+        [p('link-cycle-2'), [123, 0, 0, '', '', p('./link-cycle-1'), null]],
         // Was a symlink, now a regular file
-        [p('link-to-self'), [123, 0, 0, '', '', 0, '']],
-        [p('link-to-nowhere'), [123, 0, 0, '', '', p('./nowhere'), '']],
+        [p('link-to-self'), [123, 0, 0, '', '', 0, null]],
+        [p('link-to-nowhere'), [123, 0, 0, '', '', p('./nowhere'), null]],
         [p('node_modules/pkg/a.js'), [123, 0, 0, '', '', 0, 'a']],
         [p('node_modules/pkg/package.json'), [123, 0, 0, '', '', 0, 'pkg']],
       ]);
       expect(tfs.getDifference(newFiles)).toEqual({
         changedFiles: new Map<CanonicalPath, FileMetadata>([
-          [p('new-file'), [789, 0, 0, '', '', 0, '']],
-          [p('foo/another.js'), [124, 0, 0, '', '', 0, '']],
-          [p('link-to-self'), [123, 0, 0, '', '', 0, '']],
+          [p('new-file'), [789, 0, 0, '', '', 0, null]],
+          [p('foo/another.js'), [124, 0, 0, '', '', 0, null]],
+          [p('link-to-self'), [123, 0, 0, '', '', 0, null]],
         ]),
         removedFiles: new Set([
           p('foo/owndir'),
@@ -310,24 +310,24 @@ describe.each([['win32'], ['posix']])('TreeFS on %s', platform => {
           ([
             [
               p('a/1/package.json'),
-              [0, 0, 0, '', '', './real-package.json', ''],
+              [0, 0, 0, '', '', './real-package.json', null],
             ],
             [
               p('a/2/package.json'),
-              [0, 0, 0, '', '', './notexist-package.json', ''],
+              [0, 0, 0, '', '', './notexist-package.json', null],
             ],
-            [p('a/b/c/d/link-to-C'), [0, 0, 0, '', '', p('../../../..'), '']],
+            [p('a/b/c/d/link-to-C'), [0, 0, 0, '', '', p('../../../..'), null]],
             [
               p('a/b/c/d/link-to-B'),
-              [0, 0, 0, '', '', p('../../../../..'), ''],
+              [0, 0, 0, '', '', p('../../../../..'), null],
             ],
             [
               p('a/b/c/d/link-to-A'),
-              [0, 0, 0, '', '', p('../../../../../..'), ''],
+              [0, 0, 0, '', '', p('../../../../../..'), null],
             ],
             [
               p('n_m/workspace/link-to-pkg'),
-              [0, 0, 0, '', '', p('../../../workspace-pkg'), ''],
+              [0, 0, 0, '', '', p('../../../workspace-pkg'), null],
             ],
           ]: Array<[CanonicalPath, FileMetadata]>).concat(
             [
@@ -347,7 +347,7 @@ describe.each([['win32'], ['posix']])('TreeFS on %s', platform => {
               '../../package.json',
               '../../../a/b/package.json',
               '../workspace-pkg/package.json',
-            ].map(posixPath => [p(posixPath), [0, 0, 0, '', '', 0, '']]),
+            ].map(posixPath => [p(posixPath), [0, 0, 0, '', '', 0, null]]),
           ),
         ),
         processFile: () => {
@@ -711,8 +711,16 @@ describe.each([['win32'], ['posix']])('TreeFS on %s', platform => {
   describe('mutation', () => {
     describe('addOrModify', () => {
       test('accepts non-real and absolute paths', () => {
-        tfs.addOrModify(p('link-to-foo/new.js'), [0, 1, 0, '', '', 0, '']);
-        tfs.addOrModify(p('/project/fileatroot.js'), [0, 2, 0, '', '', 0, '']);
+        tfs.addOrModify(p('link-to-foo/new.js'), [0, 1, 0, '', '', 0, null]);
+        tfs.addOrModify(p('/project/fileatroot.js'), [
+          0,
+          2,
+          0,
+          '',
+          '',
+          0,
+          null,
+        ]);
         expect(tfs.getAllFiles().sort()).toEqual([
           p('/outside/external.js'),
           p('/project/bar.js'),
@@ -733,10 +741,10 @@ describe.each([['win32'], ['posix']])('TreeFS on %s', platform => {
           new Map<CanonicalPath, FileMetadata>([
             [
               p('newdir/link-to-link-to-bar.js'),
-              [0, 0, 0, '', '', p('../foo/link-to-bar.js'), ''],
+              [0, 0, 0, '', '', p('../foo/link-to-bar.js'), null],
             ],
-            [p('foo/baz.js'), [0, 0, 0, '', '', 0, '']],
-            [p('bar.js'), [999, 1, 0, '', '', 0, '']],
+            [p('foo/baz.js'), [0, 0, 0, '', '', 0, null]],
+            [p('bar.js'), [999, 1, 0, '', '', 0, null]],
           ]),
         );
 
@@ -830,7 +838,7 @@ describe.each([['win32'], ['posix']])('TreeFS on %s', platform => {
         {
           baseName: 'external.js',
           canonicalPath: p('../outside/external.js'),
-          metadata: [0, 0, 0, '', '', 0, ''],
+          metadata: [0, 0, 0, '', '', 0, null],
         },
         {
           baseName: 'bar.js',
@@ -868,7 +876,7 @@ describe.each([['win32'], ['posix']])('TreeFS on %s', platform => {
           {
             baseName: 'link-to-bar.js',
             canonicalPath: p('foo/link-to-bar.js'),
-            metadata: [0, 0, 0, '', '', p('../bar.js'), ''],
+            metadata: [0, 0, 0, '', '', p('../bar.js'), null],
           },
         ]),
       );
@@ -882,9 +890,9 @@ describe.each([['win32'], ['posix']])('TreeFS on %s', platform => {
       tfs = new TreeFS({
         rootDir: p('/project'),
         files: new Map<CanonicalPath, FileMetadata>([
-          [p('foo.js'), [123, 0, 0, '', 'def456', 0, '']],
-          [p('bar.js'), [123, 0, 0, '', '', 0, '']],
-          [p('link-to-bar'), [456, 0, 0, '', '', p('./bar.js'), '']],
+          [p('foo.js'), [123, 0, 0, '', 'def456', 0, null]],
+          [p('bar.js'), [123, 0, 0, '', '', 0, null]],
+          [p('link-to-bar'), [456, 0, 0, '', '', p('./bar.js'), null]],
         ]),
         processFile: mockProcessFile,
       });
@@ -958,7 +966,7 @@ describe.each([['win32'], ['posix']])('TreeFS on %s', platform => {
         {computeSha1: true},
       );
       // Simulate the file being modified while we're waiting for the SHA1.
-      tfs.addOrModify(p('bar.js'), [123, 0, 0, '', '', 0, '']);
+      tfs.addOrModify(p('bar.js'), [123, 0, 0, '', '', 0, null]);
       resolve?.('newsha1');
       expect(await getOrComputePromise).toEqual({sha1: 'newsha1'});
       // A second call re-computes
diff --git a/packages/metro-file-map/src/plugins/HastePlugin.js b/packages/metro-file-map/src/plugins/HastePlugin.js
index e63f4cf27c..6666f3b24e 100644
--- a/packages/metro-file-map/src/plugins/HastePlugin.js
+++ b/packages/metro-file-map/src/plugins/HastePlugin.js
@@ -16,7 +16,7 @@ import type {
   FileMapDelta,
   FileMapPlugin,
   FileMapPluginInitOptions,
-  FileMetadata,
+  FileMapPluginWorker,
   HasteConflict,
   HasteMap,
   HasteMapItem,
@@ -44,13 +44,16 @@ const YIELD_EVERY_NUM_HASTE_FILES = 10000;
 type HasteMapOptions = $ReadOnly<{
   console?: ?Console,
   enableHastePackages: boolean,
-  perfLogger: ?PerfLogger,
+  hasteImplModulePath?: ?string,
+  perfLogger?: ?PerfLogger,
   platforms: $ReadOnlySet<string>,
   rootDir: Path,
-  failValidationOnConflicts: boolean,
+  failValidationOnConflicts?: boolean,
 }>;
 
-export default class HastePlugin implements HasteMap, FileMapPlugin<null> {
+export default class HastePlugin
+  implements HasteMap, FileMapPlugin<null, string>
+{
   +name = 'haste';
 
   +#rootDir: Path;
@@ -59,41 +62,67 @@ export default class HastePlugin implements HasteMap, FileMapPlugin<null> {
 
   +#console: ?Console;
   +#enableHastePackages: boolean;
+  +#hasteImplCacheKey: ?string;
+  +#hasteImplModulePath: ?string;
   +#perfLogger: ?PerfLogger;
   +#pathUtils: RootPathUtils;
   +#platforms: $ReadOnlySet<string>;
   +#failValidationOnConflicts: boolean;
+  #getModuleNameByPath: string => ?string;
 
   constructor(options: HasteMapOptions) {
     this.#console = options.console ?? null;
     this.#enableHastePackages = options.enableHastePackages;
+    const hasteImplPath = options.hasteImplModulePath;
+
+    if (hasteImplPath != null) {
+      // $FlowFixMe[unsupported-syntax] - dynamic require
+      const hasteImpl = require(hasteImplPath);
+      if (typeof hasteImpl.getCacheKey !== 'function') {
+        throw new Error(
+          `HasteImpl module ${hasteImplPath} must export a function named "getCacheKey"`,
+        );
+      }
+      this.#hasteImplCacheKey = hasteImpl.getCacheKey();
+      this.#hasteImplModulePath = hasteImplPath;
+    }
+
     this.#perfLogger = options.perfLogger;
     this.#platforms = options.platforms;
     this.#rootDir = options.rootDir;
     this.#pathUtils = new RootPathUtils(options.rootDir);
-    this.#failValidationOnConflicts = options.failValidationOnConflicts;
+    this.#failValidationOnConflicts =
+      options.failValidationOnConflicts ?? false;
   }
 
-  async initialize({files}: FileMapPluginInitOptions<null>): Promise<void> {
+  async initialize({
+    files,
+  }: FileMapPluginInitOptions<null, string>): Promise<void> {
     this.#perfLogger?.point('constructHasteMap_start');
     let hasteFiles = 0;
-    for (const {baseName, canonicalPath, metadata} of files.metadataIterator({
+    for (const {
+      baseName,
+      canonicalPath,
+      data: hasteId,
+    } of files.metadataIterator({
       // Symlinks and node_modules are never Haste modules or packages.
       includeNodeModules: false,
       includeSymlinks: false,
     })) {
-      if (metadata[H.ID]) {
-        this.setModule(metadata[H.ID], [
-          canonicalPath,
-          this.#enableHastePackages && baseName === 'package.json'
-            ? H.PACKAGE
-            : H.MODULE,
-        ]);
-        if (++hasteFiles % YIELD_EVERY_NUM_HASTE_FILES === 0) {
-          await new Promise(setImmediate);
-        }
+      if (hasteId == null) {
+        continue;
+      }
+      this.setModule(hasteId, [
+        canonicalPath,
+        this.#enableHastePackages && baseName === 'package.json'
+          ? H.PACKAGE
+          : H.MODULE,
+      ]);
+      if (++hasteFiles % YIELD_EVERY_NUM_HASTE_FILES === 0) {
+        await new Promise(setImmediate);
       }
     }
+    this.#getModuleNameByPath = files.getFilePluginData;
     this.#perfLogger?.point('constructHasteMap_end');
     this.#perfLogger?.annotate({int: {hasteFiles}});
   }
@@ -126,6 +155,15 @@ export default class HastePlugin implements HasteMap, FileMapPlugin<null> {
     return null;
   }
 
+  getModuleNameByPath(mixedPath: Path): ?string {
+    if (this.#getModuleNameByPath == null) {
+      throw new Error(
+        'HastePlugin has not been initialized before getModuleNameByPath',
+      );
+    }
+    return this.#getModuleNameByPath(mixedPath) ?? null;
+  }
+
   getPackage(
     name: string,
     platform: ?string,
@@ -207,19 +245,19 @@ export default class HastePlugin implements HasteMap, FileMapPlugin<null> {
     );
   }
 
-  async bulkUpdate(delta: FileMapDelta): Promise<void> {
+  async bulkUpdate(delta: FileMapDelta<?string>): Promise<void> {
     // Process removals first so that moves aren't treated as duplicates.
-    for (const [normalPath, metadata] of delta.removed) {
-      this.onRemovedFile(normalPath, metadata);
+    for (const [normalPath, maybeHasteId] of delta.removed) {
+      this.onRemovedFile(normalPath, maybeHasteId);
     }
-    for (const [normalPath, metadata] of delta.addedOrModified) {
-      this.onNewOrModifiedFile(normalPath, metadata);
+    for (const [normalPath, maybeHasteId] of delta.addedOrModified) {
+      this.onNewOrModifiedFile(normalPath, maybeHasteId);
     }
   }
 
-  onNewOrModifiedFile(relativeFilePath: string, fileMetadata: FileMetadata) {
-    const id = fileMetadata[H.ID] || null; // Empty string indicates no module
+  onNewOrModifiedFile(relativeFilePath: string, id: ?string) {
     if (id == null) {
+      // Not a Haste module or package
       return;
     }
 
@@ -294,9 +332,9 @@ export default class HastePlugin implements HasteMap, FileMapPlugin<null> {
     hasteMapItem[platform] = module;
   }
 
-  onRemovedFile(relativeFilePath: string, fileMetadata: FileMetadata) {
-    const moduleName = fileMetadata[H.ID] || null; // Empty string indicates no module
+  onRemovedFile(relativeFilePath: string, moduleName: ?string) {
     if (moduleName == null) {
+      // Not a Haste module or package
       return;
     }
 
@@ -454,7 +492,18 @@ export default class HastePlugin implements HasteMap, FileMapPlugin<null> {
   getCacheKey(): string {
     return JSON.stringify([
       this.#enableHastePackages,
+      this.#hasteImplCacheKey,
       [...this.#platforms].sort(),
     ]);
   }
+
+  getWorker(): FileMapPluginWorker {
+    return {
+      workerModulePath: require.resolve('./haste/worker.js'),
+      workerSetupArgs: {
+        enableHastePackages: this.#enableHastePackages,
+        hasteImplModulePath: this.#hasteImplModulePath ?? null,
+      },
+    };
+  }
 }
diff --git a/packages/metro-file-map/src/plugins/MockPlugin.js b/packages/metro-file-map/src/plugins/MockPlugin.js
index 43ad69f589..d0b34f0e3e 100644
--- a/packages/metro-file-map/src/plugins/MockPlugin.js
+++ b/packages/metro-file-map/src/plugins/MockPlugin.js
@@ -13,6 +13,7 @@ import type {
   FileMapDelta,
   FileMapPlugin,
   FileMapPluginInitOptions,
+  FileMapPluginWorker,
   MockMap as IMockMap,
   Path,
   RawMockMap,
@@ -80,7 +81,7 @@ export default class MockPlugin implements FileMapPlugin<RawMockMap>, IMockMap {
             includeNodeModules: false,
             includeSymlinks: false,
           }),
-        ].map(({canonicalPath, metadata}) => [canonicalPath, metadata]),
+        ].map(({canonicalPath}) => [canonicalPath, null]),
         removed: [],
       });
     }
@@ -97,7 +98,7 @@ export default class MockPlugin implements FileMapPlugin<RawMockMap>, IMockMap {
     );
   }
 
-  async bulkUpdate(delta: FileMapDelta): Promise<void> {
+  async bulkUpdate(delta: FileMapDelta<>): Promise<void> {
     // Process removals first so that moves aren't treated as duplicates.
     for (const [relativeFilePath] of delta.removed) {
       this.onRemovedFile(relativeFilePath);
@@ -213,4 +214,8 @@ export default class MockPlugin implements FileMapPlugin<RawMockMap>, IMockMap {
       this.#mocksPattern.flags
     );
   }
+
+  getWorker(): ?FileMapPluginWorker {
+    return null;
+  }
 }
diff --git a/packages/metro-file-map/src/plugins/haste/__tests__/HastePlugin-test.js b/packages/metro-file-map/src/plugins/haste/__tests__/HastePlugin-test.js
index 513994be01..a0783e1c5c 100644
--- a/packages/metro-file-map/src/plugins/haste/__tests__/HastePlugin-test.js
+++ b/packages/metro-file-map/src/plugins/haste/__tests__/HastePlugin-test.js
@@ -9,7 +9,6 @@
  * @oncall react_native
  */
 
-import type {FileMetadata} from '../../../flow-types';
 import type HasteMapType from '../../HastePlugin';
 
 let mockPathModule;
@@ -25,22 +24,22 @@ describe.each([['win32'], ['posix']])('HastePlugin on %s', platform => {
     {
       canonicalPath: p('project/Foo.js'),
       baseName: 'Foo.js',
-      metadata: hasteMetadata('NameForFoo'),
+      data: 'NameForFoo',
     },
     {
       canonicalPath: p('project/Bar.js'),
       baseName: 'Bar.js',
-      metadata: hasteMetadata('Bar'),
+      data: 'Bar',
     },
     {
       canonicalPath: p('project/Duplicate.js'),
       baseName: 'Duplicate.js',
-      metadata: hasteMetadata('Duplicate'),
+      data: 'Duplicate',
     },
     {
       canonicalPath: p('project/other/Duplicate.js'),
       baseName: 'Duplicate.js',
-      metadata: hasteMetadata('Duplicate'),
+      data: 'Duplicate',
     },
   ];
 
@@ -73,9 +72,10 @@ describe.each([['win32'], ['posix']])('HastePlugin on %s', platform => {
           {
             canonicalPath: p('project/Foo.js'),
             baseName: 'Foo.js',
-            metadata: hasteMetadata('NameForFoo'),
+            data: 'NameForFoo',
           },
         ]),
+        getFilePluginData: jest.fn(),
       },
       pluginState: null,
     };
@@ -93,14 +93,17 @@ describe.each([['win32'], ['posix']])('HastePlugin on %s', platform => {
     beforeEach(async () => {
       hasteMap = new HasteMap(opts);
       await hasteMap.initialize({
-        files: {metadataIterator: jest.fn().mockReturnValue(INITIAL_FILES)},
+        files: {
+          metadataIterator: jest.fn().mockReturnValue(INITIAL_FILES),
+          getFilePluginData: jest.fn(),
+        },
         pluginState: null,
       });
     });
 
     test('removes a module, without affecting others', () => {
       expect(hasteMap.getModule('NameForFoo')).not.toBeNull();
-      hasteMap.onRemovedFile(p('project/Foo.js'), hasteMetadata('NameForFoo'));
+      hasteMap.onRemovedFile(p('project/Foo.js'), 'NameForFoo');
       expect(hasteMap.getModule('NameForFoo')).toBeNull();
       expect(hasteMap.getModule('Bar')).not.toBeNull();
     });
@@ -109,10 +112,7 @@ describe.each([['win32'], ['posix']])('HastePlugin on %s', platform => {
       expect(() => hasteMap.getModule('Duplicate')).toThrow(
         DuplicateHasteCandidatesError,
       );
-      hasteMap.onRemovedFile(
-        p('project/Duplicate.js'),
-        hasteMetadata('Duplicate'),
-      );
+      hasteMap.onRemovedFile(p('project/Duplicate.js'), 'Duplicate');
       expect(hasteMap.getModule('Duplicate')).toBe(
         p('/root/project/other/Duplicate.js'),
       );
@@ -125,14 +125,17 @@ describe.each([['win32'], ['posix']])('HastePlugin on %s', platform => {
     beforeEach(async () => {
       hasteMap = new HasteMap(opts);
       await hasteMap.initialize({
-        files: {metadataIterator: jest.fn().mockReturnValue(INITIAL_FILES)},
+        files: {
+          metadataIterator: jest.fn().mockReturnValue(INITIAL_FILES),
+          getFilePluginData: jest.fn(),
+        },
         pluginState: null,
       });
     });
 
     test('removes a module, without affecting others', () => {
       expect(hasteMap.getModule('NameForFoo')).not.toBeNull();
-      hasteMap.onRemovedFile(p('project/Foo.js'), hasteMetadata('NameForFoo'));
+      hasteMap.onRemovedFile(p('project/Foo.js'), 'NameForFoo');
       expect(hasteMap.getModule('NameForFoo')).toBeNull();
       expect(hasteMap.getModule('Bar')).not.toBeNull();
     });
@@ -143,12 +146,12 @@ describe.each([['win32'], ['posix']])('HastePlugin on %s', platform => {
       );
       await hasteMap.bulkUpdate({
         removed: [
-          [p('project/Duplicate.js'), hasteMetadata('Duplicate')],
-          [p('project/Foo.js'), hasteMetadata('NameForFoo')],
+          [p('project/Duplicate.js'), 'Duplicate'],
+          [p('project/Foo.js'), 'NameForFoo'],
         ],
         addedOrModified: [
-          [p('project/Baz.js'), hasteMetadata('Baz')], // New
-          [p('project/other/Bar.js'), hasteMetadata('Bar')], // New duplicate
+          [p('project/Baz.js'), 'Baz'], // New
+          [p('project/other/Bar.js'), 'Bar'], // New duplicate
         ],
       });
       expect(hasteMap.getModule('Duplicate')).toBe(
@@ -161,8 +164,35 @@ describe.each([['win32'], ['posix']])('HastePlugin on %s', platform => {
       );
     });
   });
-});
 
-function hasteMetadata(hasteName: string): FileMetadata {
-  return [0, 0, 0, '', '', 0, hasteName];
-}
+  describe('getModuleNameByPath', () => {
+    let hasteMap: HasteMapType;
+    let getFilePluginData;
+
+    beforeEach(async () => {
+      hasteMap = new HasteMap(opts);
+      getFilePluginData = jest.fn().mockReturnValue(null);
+
+      await hasteMap.initialize({
+        files: {
+          metadataIterator: jest.fn().mockReturnValue(INITIAL_FILES),
+          getFilePluginData,
+        },
+        pluginState: null,
+      });
+    });
+
+    test('returns the correct module name', () => {
+      getFilePluginData.mockImplementation(
+        filePath =>
+          ({
+            [p('/root/Foo.js')]: 'Foo' as ?string,
+            [p('/root/not-haste.js')]: null,
+          })[filePath] ?? null,
+      );
+      expect(hasteMap.getModuleNameByPath(p('/root/Foo.js'))).toBe('Foo');
+      expect(hasteMap.getModuleNameByPath(p('/root/not-haste.js'))).toBe(null);
+      expect(hasteMap.getModuleNameByPath(p('/root/not-exists.js'))).toBe(null);
+    });
+  });
+});
diff --git a/packages/metro-file-map/src/plugins/haste/types.js b/packages/metro-file-map/src/plugins/haste/types.js
new file mode 100644
index 0000000000..044ab781c2
--- /dev/null
+++ b/packages/metro-file-map/src/plugins/haste/types.js
@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict-local
+ * @format
+ */
+
+export type WorkerSetupArgs = $ReadOnly<{
+  hasteImplModulePath: string,
+  enableHastePackages: boolean,
+}>;
diff --git a/packages/metro-file-map/src/plugins/haste/worker.js b/packages/metro-file-map/src/plugins/haste/worker.js
new file mode 100644
index 0000000000..2a4779e13b
--- /dev/null
+++ b/packages/metro-file-map/src/plugins/haste/worker.js
@@ -0,0 +1,63 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict-local
+ * @format
+ */
+
+/* eslint-disable import/no-commonjs */
+
+'use strict';
+
+const excludedExtensions = require('../../workerExclusionList');
+const path = require('path');
+
+/*::
+import type {WorkerSetupArgs} from './types';
+import type {MetadataWorker, WorkerMessage, V8Serializable} from '../../flow-types';
+*/
+
+const PACKAGE_JSON = path.sep + 'package.json';
+
+module.exports = class Worker /*:: implements MetadataWorker */ {
+  #enableHastePackages /*: boolean */;
+  #hasteImpl /*: ?$ReadOnly<{getHasteName: string => ?string}> */;
+  #hasteImplModulePath /*: ?string */ = null;
+
+  constructor(setupArgs /*: WorkerSetupArgs */) {
+    this.#enableHastePackages = setupArgs.enableHastePackages;
+    if (setupArgs.hasteImplModulePath) {
+      // $FlowFixMe[unsupported-syntax] - dynamic require
+      this.#hasteImpl = require(setupArgs.hasteImplModulePath);
+    }
+  }
+
+  processFile(
+    data /*: WorkerMessage */,
+    utils /*: $ReadOnly<{getContent: () => Buffer }> */,
+  ) /*: V8Serializable */ {
+    let hasteName /*: string | null */ = null;
+    const {filePath} = data;
+    if (this.#enableHastePackages && filePath.endsWith(PACKAGE_JSON)) {
+      // Process a package.json that is returned as a PACKAGE type with its name.
+      try {
+        const fileData = JSON.parse(utils.getContent().toString());
+        if (fileData.name) {
+          hasteName = fileData.name;
+        }
+      } catch (err) {
+        throw new Error(`Cannot parse ${filePath} as JSON: ${err.message}`);
+      }
+    } else if (
+      this.#hasteImpl != null &&
+      !excludedExtensions.has(filePath.substr(filePath.lastIndexOf('.')))
+    ) {
+      // Process a random file that is returned as a MODULE.
+      hasteName = this.#hasteImpl?.getHasteName(filePath) || null;
+    }
+    return hasteName;
+  }
+};
diff --git a/packages/metro-file-map/src/plugins/mocks/__tests__/MockPlugin-test.js b/packages/metro-file-map/src/plugins/mocks/__tests__/MockPlugin-test.js
index 33fbbd3ef7..2f81febc80 100644
--- a/packages/metro-file-map/src/plugins/mocks/__tests__/MockPlugin-test.js
+++ b/packages/metro-file-map/src/plugins/mocks/__tests__/MockPlugin-test.js
@@ -100,6 +100,9 @@ Duplicate manual mock found for \`foo\`:
         metadataIterator: () => {
           throw new Error('should not be used');
         },
+        getFilePluginData: () => {
+          throw new Error('should not be used');
+        },
       },
       pluginState: {
         mocks: new Map([
diff --git a/packages/metro-file-map/src/worker.js b/packages/metro-file-map/src/worker.js
index 5c135dd397..34d3a479cb 100644
--- a/packages/metro-file-map/src/worker.js
+++ b/packages/metro-file-map/src/worker.js
@@ -13,6 +13,8 @@
 /*::
 import type {
   DependencyExtractor,
+  FileMapPluginWorker,
+  MetadataWorker,
   WorkerMessage,
   WorkerMetadata,
   WorkerSetupArgs,
@@ -25,43 +27,28 @@ const defaultDependencyExtractor = require('./lib/dependencyExtractor');
 const excludedExtensions = require('./workerExclusionList');
 const {createHash} = require('crypto');
 const fs = require('graceful-fs');
-const path = require('path');
-
-const PACKAGE_JSON = path.sep + 'package.json';
-
-let hasteImpl /*: ?{getHasteName: string => ?string} */ = null;
-let hasteImplModulePath /*: ?string */ = null;
-
-function getHasteImpl(
-  requestedModulePath /*: string */,
-) /*: {getHasteName: string => ?string} */ {
-  if (hasteImpl) {
-    if (requestedModulePath !== hasteImplModulePath) {
-      throw new Error('metro-file-map: hasteImplModulePath changed');
-    }
-    return hasteImpl;
-  }
-  hasteImplModulePath = requestedModulePath;
-  // $FlowFixMe[unsupported-syntax] - dynamic require
-  hasteImpl = require(hasteImplModulePath);
-  return hasteImpl;
-}
 
 function sha1hex(content /*: string | Buffer */) /*: string */ {
   return createHash('sha1').update(content).digest('hex');
 }
 
 class Worker {
-  constructor(args /*: WorkerSetupArgs */) {}
+  #plugins /*: $ReadOnlyArray<MetadataWorker> */;
+
+  constructor({plugins = []} /*: WorkerSetupArgs */) {
+    this.#plugins = plugins.map(({workerModulePath, workerSetupArgs}) => {
+      // $FlowFixMe[unsupported-syntax] - dynamic require
+      const PluginWorker = require(workerModulePath);
+      return new PluginWorker(workerSetupArgs);
+    });
+  }
 
   processFile(data /*: WorkerMessage */) /*: WorkerMetadata */ {
     let content /*: ?Buffer */;
     let dependencies /*: WorkerMetadata['dependencies'] */;
-    let id /*: WorkerMetadata['id'] */;
     let sha1 /*: WorkerMetadata['sha1'] */;
 
-    const {computeDependencies, computeSha1, enableHastePackages, filePath} =
-      data;
+    const {computeDependencies, computeSha1, filePath} = data;
 
     const getContent = () /*: Buffer */ => {
       if (content == null) {
@@ -71,43 +58,30 @@ class Worker {
       return content;
     };
 
-    if (enableHastePackages && filePath.endsWith(PACKAGE_JSON)) {
-      // Process a package.json that is returned as a PACKAGE type with its name.
-      try {
-        const fileData = JSON.parse(getContent().toString());
+    const workerUtils = {getContent};
+    const pluginData = this.#plugins.map(plugin =>
+      plugin.processFile(data, workerUtils),
+    );
 
-        if (fileData.name) {
-          id = fileData.name;
-        }
-      } catch (err) {
-        throw new Error(`Cannot parse ${filePath} as JSON: ${err.message}`);
-      }
-    } else if (
-      (data.hasteImplModulePath != null || computeDependencies) &&
+    if (
+      computeDependencies &&
       !excludedExtensions.has(filePath.substr(filePath.lastIndexOf('.')))
     ) {
-      // Process a random file that is returned as a MODULE.
-      if (data.hasteImplModulePath != null) {
-        id = getHasteImpl(data.hasteImplModulePath).getHasteName(filePath);
-      }
-
-      if (computeDependencies) {
-        const dependencyExtractor /*: ?DependencyExtractor */ =
-          data.dependencyExtractor != null
-            ? // $FlowFixMe[unsupported-syntax] - dynamic require
-              require(data.dependencyExtractor)
-            : null;
-
-        dependencies = Array.from(
-          dependencyExtractor != null
-            ? dependencyExtractor.extract(
-                getContent().toString(),
-                filePath,
-                defaultDependencyExtractor.extract,
-              )
-            : defaultDependencyExtractor.extract(getContent().toString()),
-        );
-      }
+      const dependencyExtractor /*: ?DependencyExtractor */ =
+        data.dependencyExtractor != null
+          ? // $FlowFixMe[unsupported-syntax] - dynamic require
+            require(data.dependencyExtractor)
+          : null;
+
+      dependencies = Array.from(
+        dependencyExtractor != null
+          ? dependencyExtractor.extract(
+              getContent().toString(),
+              filePath,
+              defaultDependencyExtractor.extract,
+            )
+          : defaultDependencyExtractor.extract(getContent().toString()),
+      );
     }
 
     // If a SHA-1 is requested on update, compute it.
@@ -116,8 +90,8 @@ class Worker {
     }
 
     return content && data.maybeReturnContent
-      ? {content, dependencies, id, sha1}
-      : {dependencies, id, sha1};
+      ? {content, dependencies, pluginData, sha1}
+      : {dependencies, pluginData, sha1};
   }
 }
 
diff --git a/packages/metro/src/node-haste/DependencyGraph.js b/packages/metro/src/node-haste/DependencyGraph.js
index c905dc9140..7f517d1653 100644
--- a/packages/metro/src/node-haste/DependencyGraph.js
+++ b/packages/metro/src/node-haste/DependencyGraph.js
@@ -381,7 +381,7 @@ export default class DependencyGraph extends EventEmitter {
   };
 
   getHasteName(filePath: string): string {
-    const hasteName = this._fileSystem.getModuleName(filePath);
+    const hasteName = this._hasteMap.getModuleNameByPath(filePath);
 
     if (hasteName) {
       return hasteName;