Create rscWebpackConfig.js for the RSC bundle

Derives from serverWebpackConfig(true) — inherits target:'node',
libraryTarget:'commonjs2', CSS filtering, and all server transforms.
Adds three RSC-specific pieces:

1. RSC WebpackLoader pushed into the babel rule's use array (runs
   before babel per right-to-left order) to detect 'use client'
   directives in raw source and replace client exports with
   registerClientReference proxies.

2. react-server resolve condition so React's RSC-specific entry
   points are used.

3. react-dom/server aliased to false (RSC bundles generate Flight
   payloads, not HTML; importing react-dom/server causes a runtime
   error).

Loader placement follows Pro dummy pattern (push into rule.use) per
docs/oss/migrating/rsc-preparing-app.md:167-195. NOT marketplace's
enforce:'post' which runs after transpilation and can miss directive
AST nodes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ihabadham

config/webpack/rscWebpackConfig.js

@@ -0,0 +1,40 @@
+const { default: serverWebpackConfig, extractLoader } = require('./serverWebpackConfig');
+
+const configureRsc = () => {
+  const rscConfig = serverWebpackConfig(true);
+
+  const rscEntry = {
+    'rsc-bundle': rscConfig.entry['server-bundle'],
+  };
+  rscConfig.entry = rscEntry;
+
+  // Runs before babel-loader (webpack loaders execute right-to-left) to
+  // detect 'use client' directives in raw source before transpilation.
+  const { rules } = rscConfig.module;
+  rules.forEach((rule) => {
+    if (Array.isArray(rule.use)) {
+      const babelLoader = extractLoader(rule, 'babel-loader');
+      if (babelLoader) {
+        rule.use.push({
+          loader: 'react-on-rails-rsc/WebpackLoader',
+        });
+      }
+    }
+  });
+
+  rscConfig.resolve = {
+    ...rscConfig.resolve,
+    conditionNames: ['react-server', '...'],
+    alias: {
+      ...rscConfig.resolve?.alias,
+      // RSC payload generation doesn't need react-dom/server; importing
+      // it in the react-server environment causes a runtime error.
+      'react-dom/server': false,
+    },
+  };
+
+  rscConfig.output.filename = 'rsc-bundle.js';
+  return rscConfig;
+};
+
+module.exports = configureRsc;