diff --git a/pubspec.yaml b/pubspec.yaml
index e784e26..c2ae3fd 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -75,4 +75,26 @@ flutter:
     - assets/audio/
     - assets/mockups/
     - assets/generated/
+    # Flutter NO recurse: declarar 'assets/content/' incluye solo los
+    # ficheros sueltos de esa carpeta, nunca los de sus subcarpetas. Todo
+    # el contenido vive en subcarpetas, asi que NADA de esto viajaba en el
+    # APK -- verificado abriendo el binario instalado: cero entradas de
+    # assets/content. El onboarding reventaba en cada arranque con
+    # 'Unable to load asset: assets/content/onboarding/en.md' aunque el
+    # fichero existe en disco. Mismo fallo de familia que los drawables
+    # resueltos por nombre: referencia sin validacion en compilacion.
     - assets/content/
+    - assets/content/onboarding/
+    - assets/content/updates/ar/
+    - assets/content/updates/bn/
+    - assets/content/updates/de/
+    - assets/content/updates/en/
+    - assets/content/updates/es/
+    - assets/content/updates/fr/
+    - assets/content/updates/hi/
+    - assets/content/updates/id/
+    - assets/content/updates/it/
+    - assets/content/updates/ja/
+    - assets/content/updates/pt/
+    - assets/content/updates/ru/
+    - assets/content/updates/zh/
diff --git a/test/assets_contenido_declarados_test.dart b/test/assets_contenido_declarados_test.dart
new file mode 100644
index 0000000..f844d23
--- /dev/null
+++ b/test/assets_contenido_declarados_test.dart
@@ -0,0 +1,55 @@
+import 'dart:io';
+
+import 'package:flutter/services.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+/// Every file under `assets/content/` must be loadable through `rootBundle`,
+/// which is the only thing that proves it is DECLARED in pubspec.yaml and
+/// therefore actually ships.
+///
+/// Found by reading the installed APK: it contained ZERO entries under
+/// `assets/content/`, while `assets/icons/alarmas/*` was present. pubspec
+/// declared `assets/content/` — and Flutter does NOT recurse: naming a
+/// directory includes the files sitting directly in it, never its
+/// subdirectories. All of this content lives in subdirectories
+/// (`onboarding/`, `updates/<locale>/`), so the entire onboarding and
+/// release-notes feature had never shipped in any build. On the device it
+/// surfaced on every launch as:
+///
+///   Unable to load asset: "assets/content/onboarding/en.md"
+///
+/// with the file plainly present on disk.
+///
+/// Same family as the drawables the resource shrinker deleted: a reference by
+/// NAME that nothing validates at compile time, so it fails only on a device.
+/// A test that merely checked `File(...).existsSync()` would have stayed green
+/// throughout — the files were never missing. Loading through `rootBundle` is
+/// what makes it a real guard, because that is the path the app itself takes.
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  final directorio = Directory('assets/content');
+  final ficheros =
+      directorio
+          .listSync(recursive: true)
+          .whereType<File>()
+          .map((f) => f.path.replaceAll(r'\', '/'))
+          .toList()
+        ..sort();
+
+  test('hay contenido que comprobar (si no, este test sería vacuo)', () {
+    expect(ficheros, isNotEmpty);
+  });
+
+  for (final ruta in ficheros) {
+    test('$ruta está declarado y se puede cargar', () async {
+      await expectLater(
+        rootBundle.loadString(ruta),
+        completes,
+        reason:
+            'existe en disco pero rootBundle no lo encuentra: falta declarar '
+            'su directorio en pubspec.yaml, y no viajará en el APK',
+      );
+    });
+  }
+}