add suggested fix from copilot

Author: paulbalandan

system/Autoloader/Autoloader.php

@@ -93,6 +93,12 @@ class Autoloader
      */
     protected $helpers = ['url'];
 
+    /**
+     * Track whether Composer namespaces have been loaded to prevent
+     * re-loading in parallel test execution contexts.
+     */
+    private bool $composerNamespacesLoaded = false;
+
     public function __construct(private readonly string $composerPath = COMPOSER_PATH)
     {
     }
@@ -109,6 +115,8 @@ public function initialize(Autoload $config, Modules $modules)
         $this->classmap = [];
         $this->files    = [];
 
+        $this->composerNamespacesLoaded = false;
+
         // We have to have one or the other, though we don't enforce the need
         // to have both present in order to work.
         if ($config->psr4 === [] && $config->classmap === []) {
@@ -150,9 +158,11 @@ private function loadComposerAutoloader(Modules $modules): void
         $composer = include $this->composerPath;
 
         // Should we load through Composer's namespaces, also?
-        if ($modules->discoverInComposer) {
+        // Guard against repeated loading in parallel execution environments
+        if ($modules->discoverInComposer && ! $this->composerNamespacesLoaded) {
             $composerPackages = $modules->composerPackages;
             $this->loadComposerNamespaces($composer, $composerPackages ?? []);
+            $this->composerNamespacesLoaded = true;
         }
 
         unset($composer);