refactor(@angular/build): consolidate library asset collection and watch check

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

@@ -107,14 +107,14 @@ export async function* executeLibraryBuilder(
       target,
     );
 
-    // Track all referenced files for watch mode
-    const allWatchedFiles = new Set<string>([
+    // Track all referenced compilation files for watch mode
+    const watchedCompilationFiles = new Set<string>([
       toPosixPath(tsConfigPath),
       toPosixPath(packageJsonPath),
     ]);
 
     for (const entryPoint of normalizedOptions.entryPoints.values()) {
-      allWatchedFiles.add(toPosixPath(entryPoint.entryFilePath));
+      watchedCompilationFiles.add(toPosixPath(entryPoint.entryFilePath));
     }
 
     if (isWatchMode) {
@@ -131,7 +131,7 @@ export async function* executeLibraryBuilder(
         poll,
         preserveSymlinks,
         signal,
-        watchFiles: allWatchedFiles,
+        watchFiles: watchedCompilationFiles,
       });
 
       context.addTeardown?.(() => void watcher?.close());
@@ -143,7 +143,7 @@ export async function* executeLibraryBuilder(
       {
         options: normalizedOptions,
         stylesheetBundler,
-        allWatchedFiles,
+        watchedCompilationFiles,
         isWatchMode,
         context,
         buildState,
@@ -162,7 +162,7 @@ export async function* executeLibraryBuilder(
       watcher,
       normalizedOptions,
       stylesheetBundler,
-      allWatchedFiles,
+      watchedCompilationFiles,
       context,
       withProgress,
       buildState,
@@ -190,7 +190,7 @@ async function executeBuild(
   buildAction: typeof import('./pipeline/build-action').buildAction,
 ): Promise<BuilderOutput> {
   const startTime = process.hrtime.bigint();
-  const { context, allWatchedFiles, isWatchMode } = actionContext;
+  const { context, watchedCompilationFiles, isWatchMode } = actionContext;
 
   try {
     await withProgress(message, () => buildAction(actionContext));
@@ -206,7 +206,14 @@ async function executeBuild(
 
     return { success: false, error: error.message };
   } finally {
-    watcher?.add(Array.from(allWatchedFiles));
+    if (watcher) {
+      watcher.add(Array.from(watchedCompilationFiles));
+
+      const { assetsToEmit } = actionContext;
+      if (assetsToEmit?.length) {
+        watcher.add(assetsToEmit.map((asset) => asset.source));
+      }
+    }
   }
 }
 
@@ -217,15 +224,15 @@ async function* runWatchLoop(
   watcher: BuildWatcher,
   options: NormalizedLibraryOptions,
   stylesheetBundler: ReturnType<typeof createComponentStylesheetBundlerForLibrary>,
-  allWatchedFiles: Set<string>,
+  watchedCompilationFiles: Set<string>,
   context: BuilderContext,
   withProgress: typeof withSpinner,
   buildState: SingleBuildState,
   buildAction: typeof import('./pipeline/build-action').buildAction,
   hasModifiedWatchedFile: typeof import('./pipeline/build-action').hasModifiedWatchedFile,
   signal?: AbortSignal,
 ): AsyncIterableIterator<BuilderOutput> {
-  const { checkAssetChanges } = await import('./pipeline/assets');
+  const { collectAssetsToEmit } = await import('./pipeline/assets');
 
   const { workspaceRoot, packageJsonPath, assets, clearScreen } = options;
   const posixPackageJsonPath = toPosixPath(packageJsonPath);
@@ -281,7 +288,7 @@ async function* runWatchLoop(
           packageJson,
           options,
           buildState,
-          allWatchedFiles,
+          watchedCompilationFiles,
           packageJsonPath,
         );
 
@@ -302,13 +309,15 @@ async function* runWatchLoop(
       !buildState.singleProgramCache ||
       buildState.hasCompilationError ||
       buildState.hasEntryPointsChanges ||
-      hasModifiedWatchedFile(changedFiles, allWatchedFiles, posixPackageJsonPath);
+      hasModifiedWatchedFile(changedFiles, watchedCompilationFiles, posixPackageJsonPath);
+
+    const assetsToEmit = await collectAssetsToEmit(
+      assets,
+      workspaceRoot,
+      buildState.hasEmittedAssets ? changedFiles : undefined,
+    );
 
-    if (
-      !hasSourceChanges &&
-      !hasPackageJsonChanges &&
-      !checkAssetChanges(assets, workspaceRoot, changedFiles)
-    ) {
+    if (!hasSourceChanges && !hasPackageJsonChanges && assetsToEmit.length === 0) {
       continue;
     }
 
@@ -317,11 +326,12 @@ async function* runWatchLoop(
       {
         options,
         stylesheetBundler,
-        allWatchedFiles,
+        watchedCompilationFiles,
         isWatchMode: true,
         context,
         buildState,
         modifiedFiles: changedFiles,
+        assetsToEmit,
       },
       withProgress,
       watcher,

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

@@ -15,30 +15,23 @@ import type { NormalizedLibraryOptions } from '../types';
 import { type DiskOutputFile, createDiskOutputFile } from './utils';
 
 /**
- * Resolves and collects configured library assets to be emitted to disk,
- * and registers their source paths with the watch set.
+ * Resolves and collects configured library assets to be emitted to disk.
  *
  * @param assets The normalized asset patterns.
  * @param workspaceRoot The workspace root directory path.
- * @param allWatchedFiles Set collecting all watched file paths for watch mode.
  * @param modifiedFiles Optional set of modified file paths for incremental copying in watch mode.
  * @returns An array of disk file emission descriptors.
  */
 export async function collectAssetsToEmit(
   assets: NormalizedLibraryOptions['assets'],
   workspaceRoot: string,
-  allWatchedFiles: Set<string>,
   modifiedFiles?: ReadonlySet<string>,
 ): Promise<DiskOutputFile[]> {
-  if (assets.length === 0) {
+  if (assets.length === 0 || modifiedFiles?.size === 0) {
     return [];
   }
 
   if (modifiedFiles) {
-    if (modifiedFiles.size === 0) {
-      return [];
-    }
-
     const matchers = createAssetMatchers(assets, workspaceRoot);
     const filesToEmit: DiskOutputFile[] = [];
 
@@ -58,7 +51,6 @@ export async function collectAssetsToEmit(
 
         if (statSync(resolvedFile, { throwIfNoEntry: false })?.isFile()) {
           filesToEmit.push(createDiskOutputFile(resolvedFile, path.join(asset.output, relative)));
-          allWatchedFiles.add(posixFile);
         }
       }
     }
@@ -67,50 +59,8 @@ export async function collectAssetsToEmit(
   }
 
   const resolvedAssets = await resolveAssets(assets, workspaceRoot);
-  const filesToEmit: DiskOutputFile[] = [];
-
-  for (const { source, destination } of resolvedAssets) {
-    filesToEmit.push(createDiskOutputFile(source, destination));
-    allWatchedFiles.add(toPosixPath(source));
-  }
-
-  return filesToEmit;
-}
-
-/**
- * Checks whether any configured library assets were modified.
- *
- * @param assets The normalized asset patterns.
- * @param workspaceRoot The workspace root directory path.
- * @param changedFiles Set of changed file paths.
- * @returns True if any asset file was modified.
- */
-export function checkAssetChanges(
-  assets: NormalizedLibraryOptions['assets'],
-  workspaceRoot: string,
-  changedFiles: ReadonlySet<string>,
-): boolean {
-  if (assets.length === 0 || changedFiles.size === 0) {
-    return false;
-  }
-
-  const matchers = createAssetMatchers(assets, workspaceRoot);
-
-  for (const file of changedFiles) {
-    const resolvedFile = path.isAbsolute(file) ? file : path.resolve(workspaceRoot, file);
-    const posixFile = toPosixPath(resolvedFile);
-
-    for (const { posixInputPrefix, isMatch } of matchers) {
-      if (posixFile.startsWith(posixInputPrefix)) {
-        const relative = posixFile.slice(posixInputPrefix.length);
-        if (isMatch(relative)) {
-          return true;
-        }
-      }
-    }
-  }
 
-  return false;
+  return resolvedAssets.map(({ source, destination }) => createDiskOutputFile(source, destination));
 }
 
 function createAssetMatchers(assets: NormalizedLibraryOptions['assets'], workspaceRoot: string) {

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

@@ -9,15 +9,15 @@
 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 { toPosixPath } from '../../../utils/path';
 import type { NormalizedLibraryOptions, SingleBuildState } from '../types';
 import { collectAssetsToEmit } from './assets';
 import { type BundleEntryPointInput, bundleEntryPoints } from './bundler';
 import { compileLibrary } from './compilation';
 import { generatePackageManifests } from './package-manifests';
-import type { createComponentStylesheetBundlerForLibrary } from './stylesheet-bundler';
-import type { OutputFile } from './utils';
+import type { DiskOutputFile, OutputFile } from './utils';
 
 /**
  * Creates a fresh {@link SingleBuildState} instance.
@@ -35,13 +35,40 @@ export function createSingleBuildState(): SingleBuildState {
  * Context required to execute a single library build iteration.
  */
 export interface BuildActionContext {
+  /** Normalized options for the library build. */
   options: NormalizedLibraryOptions;
+
+  /** The Architect builder context. */
   context: BuilderContext;
-  stylesheetBundler: ReturnType<typeof createComponentStylesheetBundlerForLibrary>;
+
+  /** Bundler instance used to process component stylesheets. */
+  stylesheetBundler: ComponentStylesheetBundler;
+
+  /** Whether the builder is running in watch mode. */
   isWatchMode: boolean;
-  allWatchedFiles: Set<string>;
+
+  /**
+   * Set of file paths tracked for compilation and configuration
+   * (including `tsconfig.json`, `package.json`, entry points, and referenced source,
+   * template, and stylesheet files). Updated during compilation and used to determine
+   * whether file changes require recompiling entry points, excluding asset files so
+   * asset-only changes do not trigger code compilation.
+   */
+  watchedCompilationFiles: Set<string>;
+
+  /** State preserved across incremental builds in watch mode. */
   buildState: SingleBuildState;
+
+  /** Set of file paths modified since the last build iteration. */
   modifiedFiles?: Set<string>;
+
+  /**
+   * Asset files to emit to disk for the current build iteration.
+   * Pre-collected in the watch loop to avoid redundant asset matching, or resolved and
+   * populated by `buildAction` when omitted (such as during the initial build) so the
+   * caller can register their source paths with the file watcher.
+   */
+  assetsToEmit?: DiskOutputFile[];
 }
 
 /**
@@ -57,7 +84,7 @@ export async function buildAction(actionContext: BuildActionContext): Promise<vo
     context,
     stylesheetBundler,
     isWatchMode,
-    allWatchedFiles,
+    watchedCompilationFiles,
     buildState,
     modifiedFiles,
   } = actionContext;
@@ -76,7 +103,7 @@ export async function buildAction(actionContext: BuildActionContext): Promise<vo
     buildState.hasEntryPointsChanges ||
     pendingChangedEsmFiles.size > 0 ||
     pendingChangedDtsFiles.size > 0 ||
-    hasModifiedWatchedFile(modifiedFiles, allWatchedFiles, posixPackageJsonPath);
+    hasModifiedWatchedFile(modifiedFiles, watchedCompilationFiles, posixPackageJsonPath);
   const shouldGenerateManifests = !buildState.hasEmittedManifests;
 
   if (shouldGenerateManifests) {
@@ -107,7 +134,7 @@ export async function buildAction(actionContext: BuildActionContext): Promise<vo
     buildState.singleProgramCache = cache;
 
     for (const file of referencedFiles) {
-      allWatchedFiles.add(file);
+      watchedCompilationFiles.add(file);
     }
 
     for (const file of changedEsmFiles) {
@@ -170,14 +197,12 @@ export async function buildAction(actionContext: BuildActionContext): Promise<vo
     filesToEmit.push(...generatePackageManifests(options, isWatchMode));
   }
 
-  filesToEmit.push(
-    ...(await collectAssetsToEmit(
-      options.assets,
-      options.workspaceRoot,
-      allWatchedFiles,
-      buildState.hasEmittedAssets ? modifiedFiles : undefined,
-    )),
-  );
+  const resolvedAssetsToEmit = (actionContext.assetsToEmit ??= await collectAssetsToEmit(
+    options.assets,
+    options.workspaceRoot,
+    buildState.hasEmittedAssets ? modifiedFiles : undefined,
+  ));
+  filesToEmit.push(...resolvedAssetsToEmit);
 
   await emitFilesToDisk<OutputFile>(filesToEmit, async (file) => {
     const fullFilePath = path.join(options.outputPath, file.path);
@@ -200,11 +225,11 @@ export async function buildAction(actionContext: BuildActionContext): Promise<vo
 
 export function hasModifiedWatchedFile(
   modifiedFiles: ReadonlySet<string>,
-  allWatchedFiles: ReadonlySet<string>,
+  watchedCompilationFiles: ReadonlySet<string>,
   posixPackageJsonPath: string,
 ): boolean {
   for (const file of modifiedFiles) {
-    if (file !== posixPackageJsonPath && allWatchedFiles.has(file)) {
+    if (file !== posixPackageJsonPath && watchedCompilationFiles.has(file)) {
       return true;
     }
   }

packages/angular/build/src/builders/library/pipeline/entry-points.ts

@@ -238,7 +238,7 @@ export function updateWatchedEntryPoints(
   packageJson: PackageJsonData,
   options: NormalizedLibraryOptions,
   buildState: SingleBuildState,
-  allWatchedFiles: Set<string>,
+  watchedCompilationFiles: Set<string>,
   packageJsonPath: string,
 ): void {
   const newEntryPoints = normalizeEntryPoints(
@@ -250,7 +250,7 @@ export function updateWatchedEntryPoints(
 
   if (haveEntryPointsChanged(options.entryPoints, newEntryPoints)) {
     for (const entryPoint of newEntryPoints.values()) {
-      allWatchedFiles.add(toPosixPath(entryPoint.entryFilePath));
+      watchedCompilationFiles.add(toPosixPath(entryPoint.entryFilePath));
     }
 
     for (const name of buildState.previousBundleResults.keys()) {