diff --git a/packages/angular/build/src/tools/angular/compilation/parallel-compilation.ts b/packages/angular/build/src/tools/angular/compilation/parallel-compilation.ts
index 3e37271ca1e6..0b58423a418b 100644
--- a/packages/angular/build/src/tools/angular/compilation/parallel-compilation.ts
+++ b/packages/angular/build/src/tools/angular/compilation/parallel-compilation.ts
@@ -66,28 +66,23 @@ export class ParallelCompilation extends AngularCompilation {
     );
 
     this.#webWorkerChannel?.port1.close();
-    this.#webWorkerChannel = undefined;
 
-    let webWorkerSignal: Int32Array | undefined;
-    if (buildType !== 'library') {
-      // The web worker processing is a synchronous operation and uses shared memory combined with
-      // the Atomics API to block execution here until a response is received.
-      const webWorkerChannel = new MessageChannel();
-      this.#webWorkerChannel = webWorkerChannel;
-      const signal = new Int32Array(new SharedArrayBuffer(4));
-      webWorkerSignal = signal;
-      webWorkerChannel.port1.on('message', ({ workerFile, containingFile }) => {
-        try {
-          const workerCodeFile = hostOptions.processWebWorker(workerFile, containingFile);
-          webWorkerChannel.port1.postMessage({ workerCodeFile });
-        } catch (error) {
-          webWorkerChannel.port1.postMessage({ error });
-        } finally {
-          Atomics.store(signal, 0, 1);
-          Atomics.notify(signal, 0);
-        }
-      });
-    }
+    // The web worker processing is a synchronous operation and uses shared memory combined with
+    // the Atomics API to block execution here until a response is received.
+    const webWorkerChannel = new MessageChannel();
+    this.#webWorkerChannel = webWorkerChannel;
+    const webWorkerSignal = new Int32Array(new SharedArrayBuffer(4));
+    webWorkerChannel.port1.on('message', ({ workerFile, containingFile }) => {
+      try {
+        const workerCodeFile = hostOptions.processWebWorker(workerFile, containingFile);
+        webWorkerChannel.port1.postMessage({ workerCodeFile });
+      } catch (error) {
+        webWorkerChannel.port1.postMessage({ error });
+      } finally {
+        Atomics.store(webWorkerSignal, 0, 1);
+        Atomics.notify(webWorkerSignal, 0);
+      }
+    });
 
     let success = false;
     try {
@@ -100,14 +95,12 @@ export class ParallelCompilation extends AngularCompilation {
           browserOnlyBuild: this.browserOnlyBuild,
           compilerOptionOverrides,
           stylesheetPort: stylesheetChannel.port2,
-          webWorkerPort: this.#webWorkerChannel?.port2,
+          webWorkerPort: webWorkerChannel.port2,
           webWorkerSignal,
         },
         {
           name: 'initialize',
-          transferList: this.#webWorkerChannel
-            ? [stylesheetChannel.port2, this.#webWorkerChannel.port2]
-            : [stylesheetChannel.port2],
+          transferList: [stylesheetChannel.port2, webWorkerChannel.port2],
         },
       );
       success = true;
diff --git a/packages/angular/build/src/tools/angular/compilation/parallel-compilation_spec.ts b/packages/angular/build/src/tools/angular/compilation/parallel-compilation_spec.ts
deleted file mode 100644
index 7157251e1ab9..000000000000
--- a/packages/angular/build/src/tools/angular/compilation/parallel-compilation_spec.ts
+++ /dev/null
@@ -1,59 +0,0 @@
-/**
- * @license
- * Copyright Google LLC All Rights Reserved.
- *
- * Use of this source code is governed by an MIT-style license that can be
- * found in the LICENSE file at https://angular.dev/license
- */
-
-import { MessageChannel } from 'node:worker_threads';
-import { AotCompilation } from './aot-compilation';
-import { initialize } from './parallel-worker';
-
-describe('parallel-worker', () => {
-  it('uses incrementing numeric request IDs for transformStylesheet and handles omitted webWorkerPort in library builds', async () => {
-    const receivedRequestIds: unknown[] = [];
-    let workerResult: string | undefined;
-
-    spyOn(AotCompilation.prototype, 'initialize').and.callFake(async (_tsconfig, hostOptions) => {
-      const [style1, style2] = await Promise.all([
-        hostOptions.transformStylesheet('body {}', '/src/a.ts', '/src/a.css', 0, 'CompA'),
-        hostOptions.transformStylesheet('div {}', '/src/b.ts', '/src/b.css', 1, 'CompB'),
-      ]);
-      expect(style1).toBe('transformed:body {}');
-      expect(style2).toBe('transformed:div {}');
-
-      workerResult = hostOptions.processWebWorker('./my.worker', '/src/a.ts');
-
-      return {
-        compilerOptions: {},
-        referencedFiles: ['/src/a.ts'],
-      };
-    });
-
-    const stylesheetChannel = new MessageChannel();
-    stylesheetChannel.port1.on('message', ({ requestId, data }) => {
-      receivedRequestIds.push(requestId);
-      stylesheetChannel.port1.postMessage({
-        requestId,
-        value: `transformed:${data}`,
-      });
-    });
-
-    try {
-      const result = await initialize({
-        jit: false,
-        browserOnlyBuild: false,
-        tsconfig: '/src/tsconfig.lib.json',
-        buildType: 'library',
-        stylesheetPort: stylesheetChannel.port2,
-      });
-
-      expect(receivedRequestIds).toEqual([1, 2]);
-      expect(workerResult).toBe('./my.worker');
-      expect(result.referencedFiles).toEqual(['/src/a.ts']);
-    } finally {
-      stylesheetChannel.port1.close();
-    }
-  });
-});
diff --git a/packages/angular/build/src/tools/angular/compilation/parallel-worker.ts b/packages/angular/build/src/tools/angular/compilation/parallel-worker.ts
index 56cbdd612d68..5bf293da727d 100644
--- a/packages/angular/build/src/tools/angular/compilation/parallel-worker.ts
+++ b/packages/angular/build/src/tools/angular/compilation/parallel-worker.ts
@@ -8,6 +8,7 @@
 
 import type { PartialMessage } from 'esbuild';
 import assert from 'node:assert';
+import { randomUUID } from 'node:crypto';
 import { type MessagePort, receiveMessageOnPort } from 'node:worker_threads';
 import { initializeHash } from '../../../utils/hash';
 import { getAndClearCumulativeDurations } from '../../../utils/profiling';
@@ -27,8 +28,8 @@ export interface InitRequest {
   fileReplacements?: Record<string, string>;
   compilerOptionOverrides?: CompilerOptionOverrides;
   stylesheetPort: MessagePort;
-  webWorkerPort?: MessagePort;
-  webWorkerSignal?: Int32Array;
+  webWorkerPort: MessagePort;
+  webWorkerSignal: Int32Array;
 }
 
 let compilation: AngularCompilation | undefined;
@@ -50,9 +51,8 @@ export async function initialize(request: InitRequest): Promise<AngularCompilati
       ? new JitCompilation(request.browserOnlyBuild)
       : new AotCompilation(request.browserOnlyBuild);
 
-    let nextRequestId = 0;
     const stylesheetRequests = new Map<
-      number,
+      string,
       [(value: string) => void, (reason: Error) => void]
     >();
     request.stylesheetPort.on('message', ({ requestId, value, error }) => {
@@ -80,7 +80,7 @@ export async function initialize(request: InitRequest): Promise<AngularCompilati
         fileReplacements: request.fileReplacements,
         modifiedFiles: currentModifiedFiles,
         transformStylesheet(data, containingFile, stylesheetFile, order, className) {
-          const requestId = ++nextRequestId;
+          const requestId = randomUUID();
           const resultPromise = new Promise<string>((resolve, reject) =>
             stylesheetRequests.set(requestId, [resolve, reject]),
           );
@@ -97,10 +97,6 @@ export async function initialize(request: InitRequest): Promise<AngularCompilati
           return resultPromise;
         },
         processWebWorker(workerFile, containingFile) {
-          if (!request.webWorkerPort || !request.webWorkerSignal) {
-            return workerFile;
-          }
-
           Atomics.store(request.webWorkerSignal, 0, 0);
           request.webWorkerPort.postMessage({ workerFile, containingFile });