Move CSS modules fix into function to ensure it applies on each call

The previous fix modified baseClientRspackConfig at module load time,
but generateWebpackConfig() returns a fresh config each time. Moving
the CSS modules configuration inside the commonRspackConfig() function
ensures the fix is applied every time the config is requested.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: justin808

config/rspack/commonRspackConfig.js

@@ -1,7 +1,6 @@
 // Common configuration applying to client and server configuration
 const { generateWebpackConfig, merge } = require('shakapacker');
 
-const baseClientRspackConfig = generateWebpackConfig();
 const commonOptions = {
   resolve: {
     extensions: ['.css', '.ts', '.tsx', '.bs.js'],
@@ -20,57 +19,61 @@ const ignoreWarningsConfig = {
   ignoreWarnings: [/Module not found: Error: Can't resolve 'react-dom\/client'/],
 };
 
-// Fix all CSS-related loaders to use default exports instead of named exports
-// Shakapacker 9 defaults to namedExport: true, but existing code expects default exports
-baseClientRspackConfig.module.rules.forEach((rule) => {
-  if (rule.use && Array.isArray(rule.use)) {
-    const cssLoader = rule.use.find((loader) => {
-      const loaderName = typeof loader === 'string' ? loader : loader?.loader;
-      return loaderName?.includes('css-loader');
-    });
-
-    if (cssLoader?.options?.modules) {
-      cssLoader.options.modules.namedExport = false;
-      cssLoader.options.modules.exportLocalsConvention = 'camelCase';
-    }
-  }
-});
+// Copy the object using merge b/c the baseClientRspackConfig and commonOptions are mutable globals
+const commonRspackConfig = () => {
+  const baseClientRspackConfig = generateWebpackConfig();
 
-const scssConfigIndex = baseClientRspackConfig.module.rules.findIndex((config) =>
-  '.scss'.match(config.test) && config.use,
-);
+  // Fix all CSS-related loaders to use default exports instead of named exports
+  // Shakapacker 9 defaults to namedExport: true, but existing code expects default exports
+  baseClientRspackConfig.module.rules.forEach((rule) => {
+    if (rule.use && Array.isArray(rule.use)) {
+      const cssLoader = rule.use.find((loader) => {
+        const loaderName = typeof loader === 'string' ? loader : loader?.loader;
+        return loaderName?.includes('css-loader');
+      });
 
-if (scssConfigIndex === -1) {
-  console.warn('No SCSS rule with use array found in rspack config');
-} else {
-  // Configure sass-loader to use the modern API
-  const scssRule = baseClientRspackConfig.module.rules[scssConfigIndex];
-  const sassLoaderIndex = scssRule.use.findIndex((loader) => {
-    if (typeof loader === 'string') {
-      return loader.includes('sass-loader');
+      if (cssLoader?.options?.modules) {
+        cssLoader.options.modules.namedExport = false;
+        cssLoader.options.modules.exportLocalsConvention = 'camelCase';
+      }
     }
-    return loader.loader && loader.loader.includes('sass-loader');
   });
 
-  if (sassLoaderIndex !== -1) {
-    const sassLoader = scssRule.use[sassLoaderIndex];
-    if (typeof sassLoader === 'string') {
-      scssRule.use[sassLoaderIndex] = {
-        loader: sassLoader,
-        options: {
-          api: 'modern'
-        }
-      };
-    } else {
-      sassLoader.options = sassLoader.options || {};
-      sassLoader.options.api = 'modern';
+  const scssConfigIndex = baseClientRspackConfig.module.rules.findIndex((config) =>
+    '.scss'.match(config.test) && config.use,
+  );
+
+  if (scssConfigIndex === -1) {
+    console.warn('No SCSS rule with use array found in rspack config');
+  } else {
+    // Configure sass-loader to use the modern API
+    const scssRule = baseClientRspackConfig.module.rules[scssConfigIndex];
+    const sassLoaderIndex = scssRule.use.findIndex((loader) => {
+      if (typeof loader === 'string') {
+        return loader.includes('sass-loader');
+      }
+      return loader.loader && loader.loader.includes('sass-loader');
+    });
+
+    if (sassLoaderIndex !== -1) {
+      const sassLoader = scssRule.use[sassLoaderIndex];
+      if (typeof sassLoader === 'string') {
+        scssRule.use[sassLoaderIndex] = {
+          loader: sassLoader,
+          options: {
+            api: 'modern'
+          }
+        };
+      } else {
+        sassLoader.options = sassLoader.options || {};
+        sassLoader.options.api = 'modern';
+      }
     }
-  }
 
-  baseClientRspackConfig.module.rules[scssConfigIndex].use.push(sassLoaderConfig);
-}
+    baseClientRspackConfig.module.rules[scssConfigIndex].use.push(sassLoaderConfig);
+  }
 
-// Copy the object using merge b/c the baseClientRspackConfig and commonOptions are mutable globals
-const commonRspackConfig = () => merge({}, baseClientRspackConfig, commonOptions, ignoreWarningsConfig);
+  return merge({}, baseClientRspackConfig, commonOptions, ignoreWarningsConfig);
+};
 
 module.exports = commonRspackConfig;