diff --git a/src/script.php b/src/script.php
index c6d0023..5fa417a 100644
--- a/src/script.php
+++ b/src/script.php
@@ -122,11 +122,14 @@ class Tpl_MokocassiopeiaInstallerScript implements InstallerScriptInterface
         // 5. Redirect update server to MokoOnyx
         $this->updateUpdateServer();
 
-        // 6. Notify
+        // 6. Unlock MokoCassiopeia (allow uninstall) + lock MokoOnyx (prevent accidental uninstall)
+        $this->updateExtensionLocks();
+
+        // 7. Notify
         $app->enqueueMessage(
             '<strong>MokoOnyx has been installed as a replacement for MokoCassiopeia.</strong><br>'
             . 'Your template settings have been migrated. MokoOnyx is now your active site template.<br>'
-            . 'You can safely uninstall MokoCassiopeia from Extensions &rarr; Manage.',
+            . 'MokoCassiopeia has been unlocked — you can uninstall it from Extensions &rarr; Manage.',
             'success'
         );
 
@@ -362,6 +365,42 @@ class Tpl_MokocassiopeiaInstallerScript implements InstallerScriptInterface
         }
     }
 
+    private function updateExtensionLocks(): void
+    {
+        $db = Factory::getDbo();
+
+        // Unlock MokoCassiopeia — allow uninstall
+        try {
+            $query = $db->getQuery(true)
+                ->update('#__extensions')
+                ->set($db->quoteName('locked') . ' = 0')
+                ->set($db->quoteName('protected') . ' = 0')
+                ->where($db->quoteName('element') . ' = ' . $db->quote(self::OLD_NAME))
+                ->where($db->quoteName('type') . ' = ' . $db->quote('template'));
+            $db->setQuery($query)->execute();
+            if ($db->getAffectedRows() > 0) {
+                $this->log('Bridge: unlocked MokoCassiopeia (can be uninstalled).');
+            }
+        } catch (\Throwable $e) {
+            $this->log('Bridge: failed to unlock MokoCassiopeia: ' . $e->getMessage(), 'warning');
+        }
+
+        // Lock MokoOnyx — prevent accidental uninstall
+        try {
+            $query = $db->getQuery(true)
+                ->update('#__extensions')
+                ->set($db->quoteName('locked') . ' = 1')
+                ->where($db->quoteName('element') . ' = ' . $db->quote(self::NEW_NAME))
+                ->where($db->quoteName('type') . ' = ' . $db->quote('template'));
+            $db->setQuery($query)->execute();
+            if ($db->getAffectedRows() > 0) {
+                $this->log('Bridge: locked MokoOnyx (protected from uninstall).');
+            }
+        } catch (\Throwable $e) {
+            $this->log('Bridge: failed to lock MokoOnyx: ' . $e->getMessage(), 'warning');
+        }
+    }
+
     // ── Logging ────────────────────────────────────────────────────────
 
     private function log(string $message, string $priority = 'info'): void