refactor: decouple core-storage services from static keys and update i18n setup to use configurable storage adapters

packages/core-i18n/README.md

@@ -2,13 +2,13 @@
 
 [← Back to Root](../../README.md)
 
-A highly decoupled, type-safe internationalization engine for the Eigen Monorepo. 
+A highly decoupled, type-safe internationalization engine for the monorepo. 
 
 It uses a **Hybrid Namespace Strategy**:
-1. **Centralized Engine**: Setup, local persistence (`@repo/core-storage`), and global words (`common`).
+1. **Centralized Engine**: Setup, local persistence orchestration, and global words (`common`).
 2. **Decentralized Dictionaries**: Feature-specific translations (`booking`, `billing`) live inside the application modules and are lazy-loaded.
 
-This architecture strictly adheres to **Inversion of Control (IoC)**. The core engine handles local state and performance, but leaves API and networking decisions entirely to the consuming applications.
+This architecture strictly adheres to **Inversion of Control (IoC)**. The core engine handles local state and performance, but leaves API, networking, and storage implementation decisions entirely to the consuming applications.
 
 ---
 
@@ -65,18 +65,29 @@ graph TD
 
 ## 1. App-Level Setup (Bootstrap)
 
-Initialize the engine *before* your React application mounts to prevent UI flashing.
+Initialize the engine *before* your React application mounts to prevent UI flashing. Provide an `I18nStorageAdapter` using Dependency Injection so the core engine can persist the user's language without being tightly coupled to a specific storage implementation.
 
 ```tsx
 // apps/web/src/main.tsx
 import { StrictMode } from 'react';
 import { createRoot } from 'react-dom/client';
 import { setupI18n } from '@repo/core-i18n';
+import { secureStorage, AppStorageKey } from './core/storage';
 import App from './app';
 
 async function bootstrap() {
-  // Synchronously reads preferred language from storage & inits i18next
-  await setupI18n();
+  // Synchronously reads preferred language from injected storage & inits i18next
+  await setupI18n({
+    storageAdapter: {
+      getLanguage: async () => {
+        const stored = await secureStorage.getItem(AppStorageKey.LOCALE);
+        return typeof stored === 'string' ? stored : null;
+      },
+      setLanguage: async (lng: string) => {
+        await secureStorage.setItem(AppStorageKey.LOCALE, lng);
+      },
+    },
+  });
 
   createRoot(document.getElementById('app')!).render(
     <StrictMode><App /></StrictMode>,

packages/core-i18n/package.json

@@ -12,7 +12,6 @@
     "typecheck": "tsc --noEmit"
   },
   "dependencies": {
-    "@repo/core-storage": "workspace:*",
     "@repo/utils": "workspace:*",
     "i18next": "^24.2.2",
     "react-i18next": "^15.4.0"

packages/core-i18n/src/manager.ts

@@ -1,5 +1,5 @@
 import i18n from 'i18next';
-import { secureStorage, StorageKey } from '@repo/core-storage';
+import { globalStorageAdapter } from './setup';
 
 /**
  * Changes the active language, saves the preference locally, and optionally syncs with the backend.
@@ -16,7 +16,9 @@ export async function changeLanguage(
   if (prevLng === newLng) return;
 
   // 1. Update local storage & i18next optimistically
-  await secureStorage.setItem(StorageKey.LOCALE, newLng);
+  if (globalStorageAdapter) {
+    await globalStorageAdapter.setLanguage(newLng);
+  }
   await i18n.changeLanguage(newLng);
 
   // 2. Trigger optional backend sync
@@ -26,7 +28,9 @@ export async function changeLanguage(
     } catch (error) {
       console.error('[i18n] Backend sync failed, rolling back language', error);
       // Rollback on failure
-      await secureStorage.setItem(StorageKey.LOCALE, prevLng);
+      if (globalStorageAdapter) {
+        await globalStorageAdapter.setLanguage(prevLng);
+      }
       await i18n.changeLanguage(prevLng);
       throw error; // Rethrow so the caller can show an error toast
     }

packages/core-i18n/src/setup.ts

@@ -1,6 +1,5 @@
 import i18n from 'i18next';
 import { initReactI18next } from 'react-i18next';
-import { secureStorage, StorageKey } from '@repo/core-storage';
 import commonEn from './locales/en/common.json';
 import commonId from './locales/id/common.json';
 
@@ -14,18 +13,33 @@ export const resources = {
   id: { common: commonId.common },
 } as const;
 
+export interface I18nStorageAdapter {
+  getLanguage(): Promise<string | null>;
+  setLanguage(lng: string): Promise<void>;
+}
+
+export interface I18nConfig {
+  storageAdapter?: I18nStorageAdapter;
+}
+
+// Store the adapter module-wide so manager.ts can access it
+export let globalStorageAdapter: I18nStorageAdapter | undefined;
+
 /**
  * Bootstraps the central i18n engine.
  *
- * This reads the preferred locale from secureStorage and initializes
- * i18next synchronously before React renders.
+ * It accepts an optional storage adapter to read the initial language.
  */
-export async function setupI18n(): Promise<void> {
+export async function setupI18n(config: I18nConfig = {}): Promise<void> {
+  globalStorageAdapter = config.storageAdapter;
+
   let initialLng = DEFAULT_LANGUAGE;
   try {
-    const storedLng = await secureStorage.getItem<string>(StorageKey.LOCALE);
-    if (storedLng && SUPPORTED_LANGUAGES.includes(storedLng as SupportedLanguage)) {
-      initialLng = storedLng;
+    if (globalStorageAdapter) {
+      const storedLng = await globalStorageAdapter.getLanguage();
+      if (storedLng && SUPPORTED_LANGUAGES.includes(storedLng as SupportedLanguage)) {
+        initialLng = storedLng;
+      }
     }
   } catch (err) {
     console.warn('[i18n] Failed to read locale from storage', err);