fix(@angular/build): copy assets replaced by a rename in watch mode

packages/angular/build/src/builders/application/build-action.ts

@@ -321,7 +321,8 @@ function* emitOutputResults(
     if (!previousAssetsInfo.has(destination)) {
       incrementalResult.added.push(destination);
       incrementalResult.background = false;
-    } else if (changes.modified.has(source)) {
+    } else if (changes.modified.has(source) || changes.added.has(source)) {
+      // A file replaced by a rename (e.g. an atomic save) can be reported as added.
       incrementalResult.modified.push(destination);
       incrementalResult.background = false;
     } else {

packages/angular/build/src/builders/application/tests/behavior/rebuild-assets_spec.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
+import { rename } from 'node:fs/promises';
 import { buildApplication } from '../../index';
 import { APPLICATION_BUILDER_INFO, BASE_OPTIONS, describeBuilder } from '../setup';
 
@@ -43,6 +44,39 @@ describeBuilder(buildApplication, APPLICATION_BUILDER_INFO, (harness) => {
       ]);
     });
 
+    it('emits an asset replaced by renaming another file over it', async () => {
+      harness.useTarget('build', {
+        ...BASE_OPTIONS,
+        assets: [
+          {
+            glob: '**/*',
+            input: 'public',
+          },
+        ],
+        watch: true,
+        // Polling reports a replaced file as modified, while native watchers can report it as added.
+        poll: undefined,
+      });
+
+      await harness.executeWithCases([
+        async ({ result }) => {
+          expect(result?.success).toBeTrue();
+          harness.expectFile('dist/browser/asset.txt').content.toContain('foo');
+
+          // Editors with atomic save write a temporary file and rename it over the original.
+          await harness.writeFile('asset.txt.tmp', 'bar');
+          await rename(
+            harness.resolvePath('asset.txt.tmp'),
+            harness.resolvePath('public/asset.txt'),
+          );
+        },
+        ({ result }) => {
+          expect(result?.success).toBeTrue();
+          harness.expectFile('dist/browser/asset.txt').content.toContain('bar');
+        },
+      ]);
+    });
+
     it('remove deleted asset from output', async () => {
       await Promise.all([
         harness.writeFile('public/asset-two.txt', 'bar'),