diff --git a/backend/app/Controllers/CurriculumController.php b/backend/app/Controllers/CurriculumController.php
index fe1c3ec..5030e59 100644
--- a/backend/app/Controllers/CurriculumController.php
+++ b/backend/app/Controllers/CurriculumController.php
@@ -239,11 +239,24 @@ class CurriculumController
                 }
             }
 
-            foreach ($tree as &$grade) foreach (($grade['subjects'] ?? []) as &$subject) foreach (($subject['semesters'] ?? []) as &$semester) foreach (($semester['units'] ?? []) as &$unit) foreach (($unit['lessons'] ?? []) as &$lesson) {
-                $path = (string)($lesson['file'] ?? '');
-                if (isset($byPath[$path])) $lesson = array_merge($lesson, $byPath[$path]);
+            foreach ($tree as $gKey => $grade) {
+                if (!isset($tree[$gKey]['subjects']) || !is_array($tree[$gKey]['subjects'])) continue;
+                foreach ($tree[$gKey]['subjects'] as $sKey => $subject) {
+                    if (!isset($tree[$gKey]['subjects'][$sKey]['semesters']) || !is_array($tree[$gKey]['subjects'][$sKey]['semesters'])) continue;
+                    foreach ($tree[$gKey]['subjects'][$sKey]['semesters'] as $semKey => $semester) {
+                        if (!isset($tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units']) || !is_array($tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units'])) continue;
+                        foreach ($tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units'] as $uKey => $unit) {
+                            if (!isset($tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units'][$uKey]['lessons']) || !is_array($tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units'][$uKey]['lessons'])) continue;
+                            foreach ($tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units'][$uKey]['lessons'] as $lKey => $lesson) {
+                                $path = (string)($lesson['file'] ?? '');
+                                if (isset($byPath[$path])) {
+                                    $tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units'][$uKey]['lessons'][$lKey] = array_merge($lesson, $byPath[$path]);
+                                }
+                            }
+                        }
+                    }
+                }
             }
-            unset($grade, $subject, $semester, $unit, $lesson);
 
             // The manifest describes intake files only. Student-visible resources
             // are rebuilt from approved, rights-cleared assets in a published
@@ -274,22 +287,24 @@ class CurriculumController
                     'type' => $group === 'textbooks' ? 'textbook' : 'worksheet',
                 ];
             }
-            foreach ($tree as &$grade) foreach (($grade['subjects'] ?? []) as $subjectKey => &$subject) {
-                $subjectResources = $resourcesBySubject[(string)$subjectKey] ?? ['textbooks' => [], 'worksheets' => []];
-                foreach (['textbooks', 'worksheets'] as $group) {
-                    foreach ($subjectResources[$group] as $index => &$resource) {
-                        $resource['title'] = $group === 'textbooks'
-                            ? 'كتاب منشور ' . ($index + 1)
-                            : 'ورقة عمل منشورة ' . ($index + 1);
+            foreach ($tree as $gKey => $grade) {
+                if (!isset($tree[$gKey]['subjects']) || !is_array($tree[$gKey]['subjects'])) continue;
+                foreach ($tree[$gKey]['subjects'] as $sKey => $subject) {
+                    $subjectResources = $resourcesBySubject[(string)$sKey] ?? ['textbooks' => [], 'worksheets' => []];
+                    foreach (['textbooks', 'worksheets'] as $group) {
+                        foreach ($subjectResources[$group] as $index => &$resource) {
+                            $resource['title'] = $group === 'textbooks'
+                                ? 'كتاب منشور ' . ($index + 1)
+                                : 'ورقة عمل منشورة ' . ($index + 1);
+                        }
+                        unset($resource);
                     }
-                    unset($resource);
+                    $tree[$gKey]['subjects'][$sKey]['resources'] = [
+                        'textbooks' => ['items' => $subjectResources['textbooks']],
+                        'worksheets' => ['items' => $subjectResources['worksheets']],
+                    ];
                 }
-                $subject['resources'] = [
-                    'textbooks' => ['items' => $subjectResources['textbooks']],
-                    'worksheets' => ['items' => $subjectResources['worksheets']],
-                ];
             }
-            unset($grade, $subject);
         } catch (\Throwable $e) { error_log('Published curriculum tree enrichment unavailable: '.$e->getMessage()); }
         $response->json(['status'=>'success','data'=>$tree]);
     }
diff --git a/backend/scripts/diagnose_tree.php b/backend/scripts/diagnose_tree.php
index cb5239d..ccc1020 100644
--- a/backend/scripts/diagnose_tree.php
+++ b/backend/scripts/diagnose_tree.php
@@ -55,14 +55,18 @@ try {
     echo "   Mapped " . count($byPath) . " paths in \$byPath lookup table.\n";
 
     $matchCount = 0;
-    foreach ($tree as &$grade) {
-        foreach (($grade['subjects'] ?? []) as &$subject) {
-            foreach (($subject['semesters'] ?? []) as &$semester) {
-                foreach (($semester['units'] ?? []) as &$unit) {
-                    foreach (($unit['lessons'] ?? []) as &$lesson) {
+    foreach ($tree as $gKey => $grade) {
+        if (!isset($tree[$gKey]['subjects']) || !is_array($tree[$gKey]['subjects'])) continue;
+        foreach ($tree[$gKey]['subjects'] as $sKey => $subject) {
+            if (!isset($tree[$gKey]['subjects'][$sKey]['semesters']) || !is_array($tree[$gKey]['subjects'][$sKey]['semesters'])) continue;
+            foreach ($tree[$gKey]['subjects'][$sKey]['semesters'] as $semKey => $semester) {
+                if (!isset($tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units']) || !is_array($tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units'])) continue;
+                foreach ($tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units'] as $uKey => $unit) {
+                    if (!isset($tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units'][$uKey]['lessons']) || !is_array($tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units'][$uKey]['lessons'])) continue;
+                    foreach ($tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units'][$uKey]['lessons'] as $lKey => $lesson) {
                         $path = (string)($lesson['file'] ?? '');
                         if (isset($byPath[$path])) {
-                            $lesson = array_merge($lesson, $byPath[$path]);
+                            $tree[$gKey]['subjects'][$sKey]['semesters'][$semKey]['units'][$uKey]['lessons'][$lKey] = array_merge($lesson, $byPath[$path]);
                             $matchCount++;
                         }
                     }
@@ -70,7 +74,6 @@ try {
             }
         }
     }
-    unset($grade, $subject, $semester, $unit, $lesson);
 
     echo "   Enriched matches in manifest.json tree: {$matchCount}\n";