diff --git a/routes/admin/courses.routes.js b/routes/admin/courses.routes.js
index 425a543..2fa24d0 100644
--- a/routes/admin/courses.routes.js
+++ b/routes/admin/courses.routes.js
@@ -3,11 +3,7 @@ const ctrl         = require("../../controllers/admin/courses.controller");
 const progressCtrl = require("../../controllers/admin/course_reading_progress.controller");
 const requirementsCtrl = require("../../controllers/admin/completion_requirements.controller");
 
-const { authenticate } = require("../../middleware/auth.middleware");
-const { requireAdmin } = require("../../middleware/rbac.middleware");
-const { adminLimiter } = require("../../middleware/rateLimiter.middleware");
-
-router.use(authenticate, requireAdmin(), adminLimiter);
+// Guards are applied by admin.routes.js (authenticate → requireAdmin → adminLimiter)
 
 // ══════════════════════════════════════════════════════════════════════════════
 // COURSES
diff --git a/tests/middleware/rateLimiter.test.js b/tests/middleware/rateLimiter.test.js
new file mode 100644
index 0000000..88a7793
--- /dev/null
+++ b/tests/middleware/rateLimiter.test.js
@@ -0,0 +1,76 @@
+'use strict';
+
+// courses.routes.js used to re-declare `router.use(authenticate, requireAdmin(), adminLimiter)`
+// on top of the guard chain admin.routes.js already applies to every mounted admin sub-router.
+// That double-application silently halved the effective adminLimiter budget (each request
+// incremented the shared store twice) and surfaced as premature "Too many admin requests"
+// errors. This suite locks in the invariant: the guard chain is applied exactly once, in
+// admin.routes.js, and never re-declared by the sub-routers it mounts.
+
+process.env.NODE_ENV = 'test';
+
+const path = require('path');
+const fs = require('fs');
+
+const { authenticate } = require('../../middleware/auth.middleware');
+const { adminLimiter } = require('../../middleware/rateLimiter.middleware');
+
+const adminRoutesDir = path.join(__dirname, '../../routes/admin');
+
+// Every admin sub-router mounted by admin.routes.js, discovered dynamically so newly
+// added route files are covered automatically.
+const subRouterFiles = fs
+  .readdirSync(adminRoutesDir)
+  .filter((f) => f.endsWith('.routes.js') && f !== 'admin.routes.js');
+
+function stackHandles(router) {
+  return router.stack.map((layer) => layer.handle);
+}
+
+describe('admin sub-routers do not re-declare inherited guards', () => {
+  test.each(subRouterFiles)('%s does not re-apply authenticate or adminLimiter', (file) => {
+    const router = require(path.join(adminRoutesDir, file));
+    const handles = stackHandles(router);
+
+    expect(handles).not.toContain(authenticate);
+    expect(handles).not.toContain(adminLimiter);
+  });
+
+  // Explicit named cases for clarity: the one that broke, plus known-good references.
+  test('courses.routes.js (regression case) has no top-level guard layer', () => {
+    const router = require(path.join(adminRoutesDir, 'courses.routes.js'));
+    const handles = stackHandles(router);
+
+    expect(handles).not.toContain(authenticate);
+    expect(handles).not.toContain(adminLimiter);
+  });
+
+  test('units.routes.js (already correct) has no top-level guard layer', () => {
+    const router = require(path.join(adminRoutesDir, 'units.routes.js'));
+    const handles = stackHandles(router);
+
+    expect(handles).not.toContain(authenticate);
+    expect(handles).not.toContain(adminLimiter);
+  });
+
+  test('lessons.routes.js (already correct) has no top-level guard layer', () => {
+    const router = require(path.join(adminRoutesDir, 'lessons.routes.js'));
+    const handles = stackHandles(router);
+
+    expect(handles).not.toContain(authenticate);
+    expect(handles).not.toContain(adminLimiter);
+  });
+});
+
+describe('admin.routes.js applies the guard chain exactly once', () => {
+  test('authenticate and adminLimiter each appear exactly one time in the stack', () => {
+    const adminRouter = require(path.join(adminRoutesDir, 'admin.routes.js'));
+    const handles = stackHandles(adminRouter);
+
+    const authCount  = handles.filter((h) => h === authenticate).length;
+    const limitCount = handles.filter((h) => h === adminLimiter).length;
+
+    expect(authCount).toBe(1);
+    expect(limitCount).toBe(1);
+  });
+});