diff --git a/Applications/Pgan.PoracleWebNet.App/ClientApp/src/app/app.config.spec.ts b/Applications/Pgan.PoracleWebNet.App/ClientApp/src/app/app.config.spec.ts
new file mode 100644
index 00000000..e8842650
--- /dev/null
+++ b/Applications/Pgan.PoracleWebNet.App/ClientApp/src/app/app.config.spec.ts
@@ -0,0 +1,46 @@
+import { HttpTestingController, provideHttpClientTesting } from '@angular/common/http/testing';
+import { TestBed } from '@angular/core/testing';
+import { TranslateService } from '@ngx-translate/core';
+
+import { appConfig } from './app.config';
+
+/**
+ * Guards the NG0200 regression introduced by the ngx-translate v18 upgrade.
+ *
+ * v18 loads `fallbackLang` eagerly from inside the TranslateService constructor. Setting it in
+ * `provideTranslateService()` therefore resolves TranslateLoader while the injector is still
+ * building TranslateService, which fails with NG0200 (circular dependency) and leaves the
+ * fallback language — English — rendering raw keys, while every other locale loaded fine.
+ *
+ * These tests exercise the real `appConfig` providers, so re-adding `fallbackLang` there fails
+ * here rather than silently in production.
+ */
+describe('appConfig translation wiring', () => {
+  beforeEach(() => {
+    TestBed.resetTestingModule();
+    TestBed.configureTestingModule({
+      providers: [...appConfig.providers, provideHttpClientTesting()],
+    });
+  });
+
+  it('constructs TranslateService without a circular dependency', () => {
+    expect(() => TestBed.inject(TranslateService)).not.toThrow();
+  });
+
+  it('does not fetch any translation before a language is requested', () => {
+    TestBed.inject(TranslateService);
+    // An eager fallback load would already have issued a request here.
+    TestBed.inject(HttpTestingController).verify();
+  });
+
+  it('loads English through the configured HTTP loader once requested', () => {
+    const translate = TestBed.inject(TranslateService);
+    const http = TestBed.inject(HttpTestingController);
+
+    translate.use('en');
+    http.expectOne('./assets/i18n/en.json').flush({ NAV: { DASHBOARD: 'Dashboard' } });
+
+    expect(translate.instant('NAV.DASHBOARD')).toBe('Dashboard');
+    http.verify();
+  });
+});
diff --git a/Applications/Pgan.PoracleWebNet.App/ClientApp/src/app/app.config.ts b/Applications/Pgan.PoracleWebNet.App/ClientApp/src/app/app.config.ts
index 0144378f..f8888de9 100644
--- a/Applications/Pgan.PoracleWebNet.App/ClientApp/src/app/app.config.ts
+++ b/Applications/Pgan.PoracleWebNet.App/ClientApp/src/app/app.config.ts
@@ -18,8 +18,17 @@ export const appConfig: ApplicationConfig = {
     // refresh + retry) before errorInterceptor redirects to the login page.
     provideHttpClient(withInterceptors([authInterceptor, errorInterceptor, oidcRefreshInterceptor])),
     provideAnimationsAsync(),
+    // No `fallbackLang` here on purpose. ngx-translate v18 loads the fallback language eagerly
+    // from inside the TranslateService constructor, which resolves TranslateLoader while the
+    // injector is still building TranslateService -- a circular dependency that fails with
+    // NG0200 ("error loading translation for en"). Only the fallback language is affected, so
+    // English silently rendered raw keys while every other locale, loaded later via use(),
+    // worked fine. v17's `defaultLanguage` did not load eagerly, which is why this only
+    // appeared after the v18 upgrade.
+    //
+    // I18nService.init() calls setFallbackLang('en') instead, after bootstrap, where the
+    // injector is complete and the loader resolves normally.
     provideTranslateService({
-      fallbackLang: 'en',
       loader: {
         provide: TranslateLoader,
         useClass: TranslateHttpLoader,
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 451a9665..4e68384a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- **English UI showed raw translation keys (`NAV.DASHBOARD`, `AUTH.SIGN_IN`) after upgrading to v2.12.0.** The ngx-translate v18 upgrade moved `defaultLanguage` to `fallbackLang`, but v18 loads the fallback language *eagerly from inside the `TranslateService` constructor*. Setting it in `provideTranslateService()` therefore resolved `TranslateLoader` while the injector was still building `TranslateService`, failing with `NG0200: Circular dependency detected`. Only the fallback language was affected, so English rendered raw keys while every other locale — loaded later via `use()` — worked normally. The fallback is now set in `I18nService.init()` after bootstrap, where the injector is complete. Regression tests exercise the real `appConfig` providers, so re-adding `fallbackLang` to the provider config fails CI.
+
 ## [2.12.0] - 2026-08-05
 
 ### Added