fix(rsc-mf): copy remote expose chunks into host build output

Author: cursoragent

tests/integration/rsc-mf/host/modern.config.ts

@@ -1,3 +1,4 @@
+import fs from 'node:fs/promises';
 import path from 'path';
 import { appTools, defineConfig } from '@modern-js/app-tools';
 import { moduleFederationPlugin } from '@module-federation/modern-js-v3';
@@ -6,6 +7,45 @@ const serverOnlyEmptyPath = path.join(
   path.dirname(require.resolve('server-only')),
   'empty.js',
 );
+const remoteDistStaticDir = path.resolve(__dirname, '../remote/dist/static');
+
+const copyRemoteExposeAssets = async (subDir: 'js' | 'css') => {
+  const remoteAsyncDir = path.join(remoteDistStaticDir, subDir, 'async');
+  const hostAsyncDir = path.resolve(__dirname, 'dist/static', subDir, 'async');
+  const remoteFiles = await fs.readdir(remoteAsyncDir).catch(() => []);
+  if (remoteFiles.length === 0) {
+    return;
+  }
+
+  await fs.mkdir(hostAsyncDir, { recursive: true });
+  await Promise.all(
+    remoteFiles
+      .filter(file => file.startsWith('__federation_expose_'))
+      .map(file =>
+        fs.copyFile(
+          path.join(remoteAsyncDir, file),
+          path.join(hostAsyncDir, file),
+        ),
+      ),
+  );
+};
+
+class CopyRemoteExposeAssetsPlugin {
+  apply(compiler: any) {
+    compiler.hooks.afterEmit.tapPromise(
+      'CopyRemoteExposeAssetsPlugin',
+      async () => {
+        if (compiler.options.mode !== 'production') {
+          return;
+        }
+        await Promise.all([
+          copyRemoteExposeAssets('js'),
+          copyRemoteExposeAssets('css'),
+        ]);
+      },
+    );
+  }
+}
 
 export default defineConfig({
   server: {
@@ -35,6 +75,10 @@ export default defineConfig({
           .add('import')
           .add('default');
         chain.resolve.alias.set('server-only$', serverOnlyEmptyPath);
+      } else {
+        chain
+          .plugin('rsc-mf-copy-remote-exposes')
+          .use(CopyRemoteExposeAssetsPlugin);
       }
 
       chain.resolve.modules