feat: complete platform core architecture upgrades

backend/logs/audit-immutable.log

@@ -153,3 +153,4 @@
 {"level":"info","logType":"audit","message":{"action":"USER_REGISTER","details":{"body":{"email":"timestamp@example.com","firstName":"Test","lastName":"Student","password":"SecurePass123!"},"method":"POST","path":"/register","query":{}},"entity":"User","entityId":null,"hash":"d7cd26b249d63d2037ea6c927cbf57214690ff3e14654eaa6cdcefdd307090d8","ipAddress":"::ffff:127.0.0.1","timestamp":"2026-06-24T11:53:47.387Z","userAgent":null,"userEmail":"timestamp@example.com","userId":null},"service":"web3-student-lab-backend","timestamp":"2026-06-24 12:53:47.387"}
 {"level":"info","logType":"audit","message":{"action":"USER_REGISTER","details":{"body":{"email":"journeystudent@example.com","firstName":"Test","lastName":"Student","password":"SecurePass123!"},"method":"POST","path":"/register","query":{}},"entity":"User","entityId":null,"hash":"6b6873394be2f87659c0a06df894f5c62302194ffedda6b45e84ad1180e423e7","ipAddress":"::ffff:127.0.0.1","timestamp":"2026-06-24T11:53:47.599Z","userAgent":null,"userEmail":"journeystudent@example.com","userId":null},"service":"web3-student-lab-backend","timestamp":"2026-06-24 12:53:47.599"}
 {"level":"info","logType":"audit","message":{"action":"TEST_MIDDLEWARE_ACTION","details":{"body":{"data":"test"},"method":"POST","path":"/test"},"entity":"TestEntity","entityId":"entity-1","hash":"5bae9c298321b23dd2f20880f6e664733b6ed0dc0f5ebff3c22d30269b891c17","ipAddress":"127.0.0.1","timestamp":"2026-06-24T11:54:19.538Z","userAgent":null,"userEmail":"test@example.com","userId":"user-1"},"service":"web3-student-lab-backend","timestamp":"2026-06-24 12:54:19.539"}
+{"level":"info","logType":"audit","message":{"action":"USER_LOGIN","timestamp":"2026-06-27T09:13:43.791Z","userId":"user-123"},"service":"web3-student-lab-backend","timestamp":"2026-06-27 09:13:43.792"}

backend/prisma/schema.prisma

@@ -294,3 +294,17 @@ model StudentActivity {
   @@map("student_activities")
 }
 
+model TranslationEntry {
+  id          String   @id @default(cuid())
+  workspaceId String   @default("default")
+  locale      String
+  namespace   String   @default("platform")
+  key         String
+  value       String
+  createdAt   DateTime @default(now())
+  updatedAt   DateTime @updatedAt
+
+  @@unique([workspaceId, locale, namespace, key])
+  @@index([workspaceId, locale, namespace])
+  @@map("translation_entries")
+}

backend/src/db/index.ts

@@ -18,6 +18,7 @@ const workspaceModels = new Set([
   'AuditLog',
   'Canvas',
   'WebhookSubscription',
+  'TranslationEntry',
 ]);
 
 

backend/src/index.ts

@@ -13,9 +13,11 @@ import config from './config/env.config.js';
 import { setRateLimitEnvOverrides } from './config/rateLimit.config.js';
 import { swaggerSpec } from './config/swagger.js';
 import prisma from './db/index.js';
+import { createGraphQLServer } from './graphql/server.js';
 import { dbRoutingMiddleware } from './middleware/dbRouting.js';
 import { decryptionMiddleware } from './middleware/encryptionMiddleware.js';
 import { errorHandler } from './middleware/errorHandler.js';
+import { createI18nMiddleware } from './middleware/i18n.js';
 import { rateLimiter } from './middleware/rateLimiter.js';
 import { requestLogger } from './middleware/requestLogger.js';
 import { requireWorkspaceMiddleware } from './middleware/WorkspaceContext.js';
@@ -26,7 +28,6 @@ import logger from './utils/logger.js';
 import { pubClient, redisConnection, subClient } from './utils/redis.js';
 import { getSentryErrorHandler, getSentryRequestHandler, initializeSentry } from './utils/sentry.js';
 import { initializeWebSocket } from './websocket/WebSocketServer.js';
-import { createGraphQLServer } from './graphql/server.js';
 
 // Load environment variables
 // dotenv.config(); // Skip in Docker Compose - use environment variables instead
@@ -158,7 +159,7 @@ async function setupGraphQL() {
   try {
     graphqlServer = await createGraphQLServer();
     const { expressMiddleware } = await import('@apollo/server/express4');
-    
+
     app.use(
       '/graphql',
       express.json(),
@@ -176,7 +177,7 @@ async function setupGraphQL() {
 setupGraphQL().catch(() => {});
 
 // API Routes - with workspace isolation
-app.use('/api/v1', requireWorkspaceMiddleware, routes);
+app.use('/api/v1', requireWorkspaceMiddleware, createI18nMiddleware(), routes);
 
 // Swagger Documentation
 app.use('/api-docs', swaggerUi.serve, swaggerUi.setup(swaggerSpec, {

backend/src/middleware/i18n.ts

@@ -0,0 +1,97 @@
+import { NextFunction, Request, Response } from 'express';
+import {
+    PrismaTranslationRepository,
+    TranslationRepository,
+} from '../services/i18n/translation.repository.js';
+
+declare global {
+  namespace Express {
+    interface Request {
+      locale?: string;
+      translationNamespace?: string;
+      t?: (key: string) => string;
+    }
+  }
+}
+
+export interface I18nOptions {
+  defaultLocale?: string;
+  supportedLocales?: string[];
+  namespace?: string;
+  repository?: TranslationRepository;
+}
+
+const FALLBACK_LOCALE = 'en';
+
+function parseAcceptLanguage(headerValue: string | undefined): string | null {
+  if (!headerValue) {
+    return null;
+  }
+
+  const first = headerValue.split(',')[0]?.trim();
+  if (!first) {
+    return null;
+  }
+
+  const language = first.split(';')[0]?.trim();
+  if (!language) {
+    return null;
+  }
+
+  const normalized = language.split('-')[0]?.toLowerCase();
+  return normalized || null;
+}
+
+function resolveLocale(req: Request, supportedLocales: string[], defaultLocale: string): string {
+  const queryLocale =
+    typeof req.query.locale === 'string'
+      ? req.query.locale
+      : typeof req.query.lang === 'string'
+        ? req.query.lang
+        : undefined;
+
+  if (queryLocale) {
+    const normalizedQuery = queryLocale.toLowerCase();
+    if (supportedLocales.includes(normalizedQuery)) {
+      return normalizedQuery;
+    }
+  }
+
+  const fromHeader = parseAcceptLanguage(req.headers['accept-language']);
+  if (fromHeader && supportedLocales.includes(fromHeader)) {
+    return fromHeader;
+  }
+
+  return defaultLocale;
+}
+
+export function createI18nMiddleware(options: I18nOptions = {}) {
+  const defaultLocale = options.defaultLocale ?? FALLBACK_LOCALE;
+  const supportedLocales = options.supportedLocales ?? ['en', 'es', 'fr', 'de'];
+  const namespace = options.namespace ?? 'platform';
+  const repository = options.repository ?? new PrismaTranslationRepository();
+
+  return async (req: Request, _res: Response, next: NextFunction) => {
+    const locale = resolveLocale(req, supportedLocales, defaultLocale);
+
+    try {
+      const localeTable = await repository.getTranslations(locale, namespace);
+      const fallbackTable =
+        locale === defaultLocale
+          ? localeTable
+          : await repository.getTranslations(defaultLocale, namespace);
+
+      req.locale = locale;
+      req.translationNamespace = namespace;
+      req.t = (key: string) => localeTable[key] ?? fallbackTable[key] ?? key;
+    } catch {
+      req.locale = defaultLocale;
+      req.translationNamespace = namespace;
+      req.t = (key: string) => key;
+    }
+
+    next();
+  };
+}
+
+export { resolveLocale };

backend/src/routes/i18n.routes.ts

@@ -0,0 +1,16 @@
+import { Router } from 'express';
+
+const router = Router();
+
+router.get('/resolve', (req, res) => {
+  const key = typeof req.query.key === 'string' ? req.query.key : 'welcome';
+
+  res.status(200).json({
+    locale: req.locale ?? 'en',
+    namespace: req.translationNamespace ?? 'platform',
+    key,
+    translation: req.t ? req.t(key) : key,
+  });
+});
+
+export default router;

backend/src/routes/index.ts

@@ -12,8 +12,10 @@ import enrollmentsRouter from './enrollments.js';
 import exportRouter from './export.routes.js';
 import generatorRouter from './generator/generator.routes.js';
 import healthRouter from './health.routes.js';
+import i18nRouter from './i18n.routes.js';
 import learningRoutes from './learning/learning.routes.js';
 import securityRouter from './security.routes.js';
+import seoRouter from './seo.routes.js';
 import studentsRouter from './students.js';
 
 import notificationRouter from '../notifications/notification.routes.js';
@@ -38,6 +40,8 @@ router.use('/contracts', contractRouter);
 router.use('/notifications', notificationRouter);
 router.use('/notifications/preferences', notificationPreferencesRouter);
 router.use('/security', securityRouter);
+router.use('/seo', seoRouter);
+router.use('/i18n', i18nRouter);
 router.use('/generator', generatorRouter);
 router.use('/export', exportRouter);
 router.use('/webhooks', webhooksRouter);

backend/src/routes/seo.routes.ts

@@ -0,0 +1,27 @@
+import { Router } from 'express';
+import { simulatorSeoService } from '../services/seo/simulatorSeo.service.js';
+
+const router = Router();
+
+router.get('/simulator/meta/:slug', async (req, res) => {
+  const { slug } = req.params;
+  const meta = await simulatorSeoService.getMetaTags(slug);
+
+  if (!meta) {
+    res.status(404).json({ error: `No simulator metadata found for slug: ${slug}` });
+    return;
+  }
+
+  res.status(200).json({ slug, meta });
+});
+
+router.get('/simulator/sitemap', async (_req, res) => {
+  const urls = await simulatorSeoService.getSitemapUrls();
+  res.status(200).json({ count: urls.length, urls });
+});
+
+router.get('/simulator/cache-stats', (_req, res) => {
+  res.status(200).json(simulatorSeoService.getCacheStats());
+});
+
+export default router;

backend/src/services/i18n/translation.repository.ts

@@ -0,0 +1,59 @@
+export interface TranslationRecord {
+  locale: string;
+  namespace: string;
+  key: string;
+  value: string;
+}
+
+export interface TranslationRepository {
+  getTranslations(locale: string, namespace: string): Promise<Record<string, string>>;
+}
+
+export class PrismaTranslationRepository implements TranslationRepository {
+  async getTranslations(locale: string, namespace: string): Promise<Record<string, string>> {
+    const { default: prisma } = await import('../../db/index.js');
+
+    const rows = await prisma.translationEntry.findMany({
+      where: {
+        locale,
+        namespace,
+      },
+      select: {
+        key: true,
+        value: true,
+      },
+    });
+
+    return rows.reduce<Record<string, string>>((acc, row) => {
+      acc[row.key] = row.value;
+      return acc;
+    }, {});
+  }
+}
+
+export class InMemoryTranslationRepository implements TranslationRepository {
+  private readonly table = new Map<string, string>();
+
+  constructor(rows: TranslationRecord[] = []) {
+    for (const row of rows) {
+      this.table.set(this.makeKey(row.locale, row.namespace, row.key), row.value);
+    }
+  }
+
+  async getTranslations(locale: string, namespace: string): Promise<Record<string, string>> {
+    const prefix = `${locale}:${namespace}:`;
+    const result: Record<string, string> = {};
+
+    for (const [compositeKey, value] of this.table.entries()) {
+      if (compositeKey.startsWith(prefix)) {
+        result[compositeKey.slice(prefix.length)] = value;
+      }
+    }
+
+    return result;
+  }
+
+  private makeKey(locale: string, namespace: string, key: string): string {
+    return `${locale}:${namespace}:${key}`;
+  }
+}