feat: wire translations into runtime via site.i18n webpack alias

- Add `site.i18n` webpack alias (dev, build, dev-shell configs) using a
  new `getResolvedSiteI18nPath` utility mirroring `getResolvedSiteConfigPath`
- Declare `site.i18n` module in `frontend-base.d.ts` using new `SiteMessages`
  type (`LocalizedMessages[]`) added to `types.ts`
- Remove `App.messages`, `addAppMessages()`, and `shell/i18n/` placeholder —
  all translations now flow through `initialize({ messages })` from the
  site-level pull
- Add `test-site/src/i18n/index.ts` (empty array) for the dev shell

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: brian-smith-tcril

frontend-base.d.ts

@@ -2,6 +2,10 @@ declare module 'site.config' {
   export default SiteConfig;
 }
 
+declare module 'site.i18n' {
+  export default SiteMessages;
+}
+
 declare module '*.svg' {
   const content: string;
   export default content;

runtime/i18n/index.js

@@ -97,7 +97,6 @@ export {
 } from 'react-intl';
 
 export {
-  addAppMessages,
   configureI18n,
   getLocale,
   getLocalizedLanguageName,

runtime/i18n/lib.ts

@@ -237,20 +237,6 @@ export function mergeMessages(newMessages = {}) {
   return messages;
 }
 
-/**
- * Adds all the messages found in the loaded apps.
- *
- * @memberof module:Internationalization
- */
-export function addAppMessages() {
-  const { apps } = getSiteConfig();
-  if (apps) {
-    apps.forEach((app) => {
-      mergeMessages(app.messages);
-    });
-  }
-}
-
 interface ConfigureI18nOptions {
   messages: LocalizedMessages[] | LocalizedMessages,
 }

shell/dev/devHome/app.ts

@@ -1,6 +1,5 @@
 import { App } from '../../../types';
 import HomePage from './HomePage';
-import messages from './i18n';
 
 const app: App = {
   appId: 'org.openedx.frontend.app.dev.home',
@@ -12,7 +11,6 @@ const app: App = {
       role: 'org.openedx.frontend.role.devHome'
     }
   }],
-  messages,
 };
 
 export default app;

shell/i18n/index.ts

@@ -10,16 +10,14 @@ import {
   subscribe
 } from '../runtime';
 import { addAppConfigs } from '../runtime/config';
-import { addAppMessages } from '../runtime/i18n';
-import messages from './i18n';
+import messages from 'site.i18n';
 import createRouter from './router/createRouter';
 
 subscribe(SITE_READY, async () => {
   const queryClient = new QueryClient();
   const router = createRouter();
 
   addAppConfigs();
-  addAppMessages();
 
   const root = createRoot(document.getElementById('root') as HTMLElement);
   root.render(

shell/site.tsx

@@ -1,5 +1,4 @@
 import { App, LinkMenuItem, WidgetOperationTypes } from '@openedx/frontend-base';
-import messages from './i18n';
 
 const config: App = {
   appId: 'test-authenticated-page-app',
@@ -22,7 +21,6 @@ const config: App = {
       )
     }
   ],
-  messages,
 };
 
 export default config;

test-site/src/authenticated-page/index.tsx

@@ -0,0 +1 @@
+export default [];

test-site/src/i18n/index.ts

@@ -0,0 +1,23 @@
+import fs from 'fs';
+import path from 'path';
+
+export default function getResolvedSiteI18nPath(defaultDirname: string) {
+  const siteI18nPath = process.env.SITE_I18N_PATH;
+
+  if (siteI18nPath !== undefined) {
+    const absolutePath = path.resolve(process.cwd(), siteI18nPath);
+    if (fs.existsSync(absolutePath)) {
+      return absolutePath;
+    }
+    console.error(`Invalid site i18n path (${siteI18nPath}) specified as an environment variable. Aborting.`);
+    process.exit(1);
+  }
+
+  const defaultPath = path.resolve(process.cwd(), defaultDirname);
+  if (fs.existsSync(defaultPath)) {
+    return defaultPath;
+  }
+
+  console.error(`Default site i18n directory (${defaultPath}) does not exist. Aborting.`);
+  process.exit(1);
+}

tools/webpack/utils/getResolvedSiteI18nPath.ts

@@ -16,8 +16,10 @@ import {
 
 import getPublicPath from './utils/getPublicPath';
 import getResolvedSiteConfigPath from './utils/getResolvedSiteConfigPath';
+import getResolvedSiteI18nPath from './utils/getResolvedSiteI18nPath';
 
 const resolvedSiteConfigPath = getResolvedSiteConfigPath('site.config.build.tsx');
+const resolvedSiteI18nPath = getResolvedSiteI18nPath('src/i18n');
 
 const config: Configuration = {
   mode: 'production',
@@ -34,6 +36,7 @@ const config: Configuration = {
   resolve: {
     alias: {
       'site.config': resolvedSiteConfigPath,
+      'site.i18n': resolvedSiteI18nPath,
     },
     plugins: [
       new TsconfigPathsPlugin({