refactor(@angular/build): unify and deduplicate emitFilesToDisk across builders

Relocate emitFilesToDisk into src/utils/emit-files-to-disk.ts and unify the file emission descriptor shape across the application and library builders around origin ('memory' | 'disk') and source.

Update emitFilesToDisk to manage per-invocation parent directory creation internally with bounded concurrency, allowing application/index.ts, library/pipeline/build-action.ts, and utils/test-files.ts to share the same helper. This also removes the cross-rebuild directoryExists cache from the library builder's SingleBuildState so deleted output subdirectories are properly recreated during watch mode rebuilds.

Author: alan-agius4

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

@@ -333,7 +333,7 @@ function* emitOutputResults(
     incrementalResult.files.push({
       path: destination,
       type: BuildOutputFileType.Browser,
-      inputPath: source,
+      source: source,
       origin: 'disk',
     });
   }
@@ -406,7 +406,7 @@ function createFullResult(
       ...assetFiles.map(({ source, destination }) => ({
         path: destination,
         type: BuildOutputFileType.Browser,
-        inputPath: source,
+        source,
         origin: 'disk' as const,
       })),
       ...outputFiles.map((file) => ({

packages/angular/build/src/builders/application/index.ts

@@ -11,9 +11,10 @@ import assert from 'node:assert';
 import fs from 'node:fs/promises';
 import path from 'node:path';
 import { BuildOutputFileType } from '../../tools/esbuild/bundler-files';
-import { createJsonBuildManifest, emitFilesToDisk } from '../../tools/esbuild/utils';
+import { createJsonBuildManifest } from '../../tools/esbuild/utils';
 import { colors as ansiColors } from '../../utils/color';
 import { deleteOutputDir } from '../../utils/delete-output-dir';
+import { emitFilesToDisk } from '../../utils/emit-files-to-disk';
 import { bazelEsbuildPluginPath, useJSONBuildLogs } from '../../utils/environment-options';
 import { isSubDirectory } from '../../utils/path';
 import { purgeStaleBuildCache } from '../../utils/purge-cache';
@@ -197,37 +198,14 @@ export async function* buildApplication(
     }
 
     // Writes the output files to disk and ensures the containing directories are present
-    const directoryExists = new Set<string>();
     try {
-      await emitFilesToDisk(result.files, async (file) => {
-        if (
-          outputOptions.ignoreServer &&
-          (file.type === BuildOutputFileType.ServerApplication ||
-            file.type === BuildOutputFileType.ServerRoot)
-        ) {
-          return;
-        }
-
-        const fullFilePath = generateFullPath(file.path, file.type, outputOptions);
-
-        // Ensure output subdirectories exist
-        const fileBasePath = path.dirname(fullFilePath);
-        if (fileBasePath && !directoryExists.has(fileBasePath)) {
-          await fs.mkdir(fileBasePath, { recursive: true });
-          directoryExists.add(fileBasePath);
-        }
-
-        if (file.origin === 'memory') {
-          // Write file contents
-          await fs.writeFile(fullFilePath, file.contents);
-        } else {
-          // Copy file contents
-          await fs.cp(file.inputPath, fullFilePath, {
-            mode: fs.constants.COPYFILE_FICLONE,
-            preserveTimestamps: true,
-          });
-        }
-      });
+      await emitFilesToDisk(result.files, (file) =>
+        outputOptions.ignoreServer &&
+        (file.type === BuildOutputFileType.ServerApplication ||
+          file.type === BuildOutputFileType.ServerRoot)
+          ? undefined
+          : generateFullPath(file.path, file.type, outputOptions),
+      );
     } catch (error) {
       context.logger.error(error instanceof Error ? error.message : String(error));
       yield { success: false };

packages/angular/build/src/builders/application/results.ts

@@ -53,7 +53,7 @@ export interface BaseResultFile {
 
 export interface DiskFile extends BaseResultFile {
   origin: 'disk';
-  inputPath: string;
+  source: string;
 }
 
 export interface MemoryFile extends BaseResultFile {

packages/angular/build/src/builders/dev-server/vite/utils.ts

@@ -40,7 +40,7 @@ export function updateResultRecord(
 ): void {
   if (file.origin === 'disk') {
     assetFiles.set('/' + normalizePath(file.path), {
-      source: normalizePath(file.inputPath),
+      source: normalizePath(file.source),
       updated: !initial,
     });
 

packages/angular/build/src/builders/extract-i18n/application-extraction.ts

@@ -107,7 +107,7 @@ function setupLocalizeExtractor(
       if (file?.origin === 'memory') {
         content = textDecoder.decode(file.contents);
       } else if (file?.origin === 'disk') {
-        content = readFileSync(file.inputPath, 'utf-8');
+        content = readFileSync(file.source, 'utf-8');
       }
       if (content === undefined) {
         throw new Error('Unknown file requested: ' + requestedPath);

packages/angular/build/src/builders/karma/assets-middleware.ts

@@ -60,7 +60,7 @@ export class AngularAssetsMiddleware {
     // https://github.com/karma-runner/karma/blob/84f85e7016efc2266fa6b3465f494a3fa151c85c/lib/middleware/common.js#L10
     switch (file.origin) {
       case 'disk':
-        this.serveFile(file.inputPath, undefined, res, undefined, undefined, /* doNotCache */ true);
+        this.serveFile(file.source, undefined, res, undefined, undefined, /* doNotCache */ true);
         break;
       case 'memory':
         // Include pathname to help with Content-Type headers.

packages/angular/build/src/builders/library/pipeline/build-action.ts

@@ -7,10 +7,9 @@
  */
 
 import type { BuilderContext } from '@angular-devkit/architect';
-import { constants, copyFile, mkdir, writeFile } from 'node:fs/promises';
 import path from 'node:path';
 import type { ComponentStylesheetBundler } from '../../../tools/esbuild/angular/component-stylesheets';
-import { emitFilesToDisk } from '../../../tools/esbuild/utils';
+import { emitFilesToDisk } from '../../../utils/emit-files-to-disk';
 import { toPosixPath } from '../../../utils/path';
 import type { NormalizedLibraryOptions, SingleBuildState } from '../types';
 import { collectAssetsToEmit } from './assets';
@@ -27,7 +26,6 @@ export function createSingleBuildState(): SingleBuildState {
     previousBundleResults: new Map(),
     pendingChangedEsmFiles: new Set(),
     pendingChangedDtsFiles: new Set(),
-    directoryExists: new Set(),
   };
 }
 
@@ -90,7 +88,7 @@ export async function buildAction(actionContext: BuildActionContext): Promise<vo
   } = actionContext;
 
   const posixPackageJsonPath = toPosixPath(options.packageJsonPath);
-  const { pendingChangedEsmFiles, pendingChangedDtsFiles, directoryExists } = buildState;
+  const { pendingChangedEsmFiles, pendingChangedDtsFiles } = buildState;
 
   if (!modifiedFiles || modifiedFiles.has(posixPackageJsonPath)) {
     buildState.hasEmittedManifests = false;
@@ -231,20 +229,7 @@ export async function buildAction(actionContext: BuildActionContext): Promise<vo
   ));
   filesToEmit.push(...resolvedAssetsToEmit);
 
-  await emitFilesToDisk<OutputFile>(filesToEmit, async (file) => {
-    const fullFilePath = path.join(options.outputPath, file.path);
-    const fileBasePath = path.dirname(fullFilePath);
-    if (fileBasePath && !directoryExists.has(fileBasePath)) {
-      await mkdir(fileBasePath, { recursive: true });
-      directoryExists.add(fileBasePath);
-    }
-
-    if (file.type === 'memory') {
-      await writeFile(fullFilePath, file.contents);
-    } else {
-      await copyFile(file.source, fullFilePath, constants.COPYFILE_FICLONE);
-    }
-  });
+  await emitFilesToDisk(filesToEmit, (file) => path.join(options.outputPath, file.path));
 
   buildState.hasEmittedManifests = true;
   buildState.hasEmittedTslib = hasTslibImport;

packages/angular/build/src/builders/library/pipeline/utils.ts

@@ -26,7 +26,7 @@ export const TYPES_OUTPUT_DIR = 'types';
  * Represents an in-memory file to be emitted to disk.
  */
 export interface MemoryOutputFile {
-  type: 'memory';
+  origin: 'memory';
 
   /** The destination path where the file should be written. */
   path: string;
@@ -39,7 +39,7 @@ export interface MemoryOutputFile {
  * Represents an existing file on disk to be copied to a destination path.
  */
 export interface DiskOutputFile {
-  type: 'disk';
+  origin: 'disk';
 
   /** The path to the source file on disk. */
   source: string;
@@ -62,7 +62,7 @@ export type OutputFile = MemoryOutputFile | DiskOutputFile;
  */
 export function createDiskOutputFile(source: string, path: string): DiskOutputFile {
   return {
-    type: 'disk',
+    origin: 'disk',
     source,
     path,
   };
@@ -80,7 +80,7 @@ export function createMemoryOutputFile(
   contents: string | Uint8Array | Record<string, unknown>,
 ): MemoryOutputFile {
   return {
-    type: 'memory',
+    origin: 'memory',
     path,
     contents:
       typeof contents === 'string' || contents instanceof Uint8Array

packages/angular/build/src/builders/library/tests/behavior/watch_spec.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
+import { rm } from 'node:fs/promises';
 import { executeLibraryBuilder } from '../../builder';
 import { BASE_OPTIONS, LIBRARY_BUILDER_INFO, describeLibraryBuilder } from '../setup';
 
@@ -563,5 +564,42 @@ describeLibraryBuilder(executeLibraryBuilder, LIBRARY_BUILDER_INFO, (harness) =>
         },
       ]);
     });
+
+    it('should recreate deleted output directories on subsequent watch rebuilds', async () => {
+      harness.useTarget('build', {
+        ...BASE_OPTIONS,
+        watch: true,
+      });
+
+      await harness.executeWithCases([
+        async ({ result }) => {
+          expect(result?.success).toBeTrue();
+          expect(harness.hasFile('dist/lib/fesm2022/lib.mjs')).toBeTrue();
+
+          // Remove output subdirectory externally between rebuilds
+          await rm(harness.resolvePath('dist/lib/fesm2022'), { recursive: true, force: true });
+          expect(harness.hasFile('dist/lib/fesm2022/lib.mjs')).toBeFalse();
+
+          // Trigger a rebuild
+          await harness.writeFile(
+            'projects/lib/src/lib/lib.component.ts',
+            `
+            import { Component } from '@angular/core';
+
+            @Component({
+              selector: 'lib-recreated',
+              template: '<span>Recreated</span>',
+            })
+            export class LibComponent {}
+            `,
+          );
+        },
+        async ({ result }) => {
+          expect(result?.success).toBeTrue();
+          const content = harness.readFile('dist/lib/fesm2022/lib.mjs');
+          expect(content).toContain('lib-recreated');
+        },
+      ]);
+    });
   });
 });

packages/angular/build/src/builders/library/types.ts

@@ -153,7 +153,4 @@ export interface SingleBuildState {
 
   /** Whether entry points in package.json changed since the last compilation. */
   hasEntryPointsChanges?: boolean;
-
-  /** Cache of output directory paths known to exist on disk. */
-  directoryExists: Set<string>;
 }