feat(build): support copying library assets in monorepo builds

actions/build.action.ts

@@ -128,6 +128,37 @@ export class BuildAction extends AbstractAction {
         watchAssetsMode,
       );
 
+      const includeLibraryAssets = getValueOrDefault<boolean>(
+        configuration,
+        'compilerOptions.includeLibraryAssets',
+        appName,
+        'includeLibraryAssets',
+        commandOptions,
+      );
+      if (includeLibraryAssets && configuration.projects) {
+        for (const [projectName, project] of Object.entries(
+          configuration.projects,
+        )) {
+          if (projectName === appName) {
+            continue;
+          }
+          if (
+            project &&
+            project.type === 'library' &&
+            project.compilerOptions &&
+            Array.isArray(project.compilerOptions.assets) &&
+            project.compilerOptions.assets.length > 0
+          ) {
+            this.assetsManager.copyAssets(
+              configuration,
+              projectName,
+              outDir,
+              watchAssetsMode,
+            );
+          }
+        }
+      }
+
       const typeCheck = getValueOrDefault<boolean>(
         configuration,
         'compilerOptions.typeCheck',
@@ -220,9 +251,8 @@ export class BuildAction extends AbstractAction {
     watchMode: boolean,
     onSuccess: (() => void) | undefined,
   ) {
-    const { WebpackCompiler } = await import(
-      '../lib/compiler/webpack-compiler'
-    );
+    const { WebpackCompiler } =
+      await import('../lib/compiler/webpack-compiler');
     const webpackCompiler = new WebpackCompiler(this.pluginsLoader);
 
     const webpackPath =

commands/build.command.ts

@@ -24,6 +24,10 @@ export class BuildCommand extends AbstractCommand {
         'Use "preserveWatchOutput" option when using tsc watch mode.',
       )
       .option('--all', 'Build all projects in a monorepo.')
+      .option(
+        '--include-library-assets',
+        'Also copy assets from library projects when building an app in a monorepo.',
+      )
       .description('Build Nest application.')
       .action(async (apps: string[], command: Command) => {
         const options: Input[] = [];
@@ -76,6 +80,11 @@ export class BuildCommand extends AbstractCommand {
 
         options.push({ name: 'all', value: !!command.all });
 
+        options.push({
+          name: 'includeLibraryAssets',
+          value: command.includeLibraryAssets,
+        });
+
         const inputs: Input[] = apps.map((app) => ({
           name: 'app',
           value: app,

lib/compiler/helpers/get-value-or-default.ts

@@ -13,7 +13,8 @@ export function getValueOrDefault<T = any>(
     | 'sourceRoot'
     | 'exec'
     | 'builder'
-    | 'typeCheck',
+    | 'typeCheck'
+    | 'includeLibraryAssets',
   options: Input[] = [],
   defaultValue?: T,
 ): T {

lib/configuration/configuration.ts

@@ -66,6 +66,12 @@ export interface CompilerOptions {
   deleteOutDir?: boolean;
   manualRestart?: boolean;
   builder?: Builder;
+  /**
+   * When building an application in a monorepo, also copy assets configured
+   * for sibling library projects into the application's output directory.
+   * Disabled by default to preserve backward compatibility.
+   */
+  includeLibraryAssets?: boolean;
 }
 
 export interface PluginOptions {