fix(@angular/build): ensure asset followSymlinks defaults to false

When `followSymlinks` is omitted from an asset configuration entry, its value is `undefined`. Because `tinyglobby` treats `followSymbolicLinks: undefined` as `true`, symlinked subdirectories within asset folders were traversed even though the schema documents the default as `false`.

Coerce `entry.followSymlinks` to a boolean (`entry.followSymlinks ?? false`) so the runtime behavior matches the documented schema default and the existing Webpack builder behavior.

Closes angular#34164

Author: alan-agius4

packages/angular/build/src/builders/application/tests/options/assets_spec.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
+import fs from 'node:fs/promises';
 import { buildApplication } from '../../index';
 import { APPLICATION_BUILDER_INFO, BASE_OPTIONS, describeBuilder } from '../setup';
 
@@ -408,6 +409,44 @@ describeBuilder(buildApplication, APPLICATION_BUILDER_INFO, (harness) => {
 
         harness.expectFile('dist/browser/test.svg').toNotExist();
       });
+
+      it('does not follow symlink directories by default', async () => {
+        await harness.writeFile('target/test.txt', 'symlink-content');
+        await fs.symlink(
+          harness.resolvePath('target'),
+          harness.resolvePath('src/symlink-dir'),
+          'junction',
+        );
+
+        harness.useTarget('build', {
+          ...BASE_OPTIONS,
+          assets: [{ glob: '**/*', input: 'src' }],
+        });
+
+        const { result } = await harness.executeOnce();
+
+        expect(result?.success).toBe(true);
+        harness.expectFile('dist/browser/symlink-dir/test.txt').toNotExist();
+      });
+
+      it('follows symlink directories when followSymlinks is true', async () => {
+        await harness.writeFile('target/test.txt', 'symlink-content');
+        await fs.symlink(
+          harness.resolvePath('target'),
+          harness.resolvePath('src/symlink-dir'),
+          'junction',
+        );
+
+        harness.useTarget('build', {
+          ...BASE_OPTIONS,
+          assets: [{ glob: '**/*', input: 'src', followSymlinks: true }],
+        });
+
+        const { result } = await harness.executeOnce();
+
+        expect(result?.success).toBe(true);
+        harness.expectFile('dist/browser/symlink-dir/test.txt').content.toBe('symlink-content');
+      });
     });
   });
 });

packages/angular/build/src/utils/resolve-assets.ts

@@ -39,7 +39,7 @@ export async function resolveAssets(
       cwd,
       dot: true,
       ignore: entry.ignore ? [...DEFAULT_ASSET_IGNORE, ...entry.ignore] : DEFAULT_ASSET_IGNORE,
-      followSymbolicLinks: entry.followSymlinks,
+      followSymbolicLinks: entry.followSymlinks ?? false,
     });
 
     for (const file of files) {

packages/angular_devkit/build_angular/src/utils/copy-assets.ts

@@ -33,7 +33,7 @@ export async function copyAssets(
       cwd,
       dot: true,
       ignore: entry.ignore ? defaultIgnore.concat(entry.ignore) : defaultIgnore,
-      followSymbolicLinks: entry.followSymlinks,
+      followSymbolicLinks: entry.followSymlinks ?? false,
     });
 
     const directoryExists = new Set<string>();