diff --git a/tests/Unit/RouterTest.php b/tests/Unit/RouterTest.php
index a5584cd..f294816 100644
--- a/tests/Unit/RouterTest.php
+++ b/tests/Unit/RouterTest.php
@@ -4,6 +4,7 @@ namespace Tests\Unit;
 
 use Exception;
 use Libs\Neuron;
+use Libs\Request;
 use Libs\Router;
 use LogicException;
 use PDOException;
@@ -25,10 +26,14 @@ use TypeError;
 final class RouterTest extends TestCase
 {
     private array $serverBackup = [];
+    private array $getBackup = [];
+    private array $postBackup = [];
 
     protected function setUp(): void
     {
         $this->serverBackup = $_SERVER;
+        $this->getBackup = $_GET;
+        $this->postBackup = $_POST;
         $_SERVER['REQUEST_METHOD'] = 'GET';
         unset($_SERVER['HTTP_ACCEPT']);
         http_response_code(200);
@@ -38,6 +43,8 @@ final class RouterTest extends TestCase
     protected function tearDown(): void
     {
         $_SERVER = $this->serverBackup;
+        $_GET = $this->getBackup;
+        $_POST = $this->postBackup;
         http_response_code(200);
         $this->resetRouterState();
     }
@@ -206,4 +213,56 @@ final class RouterTest extends TestCase
         $this->assertSame('{"status":"ok"}', $output);
         $this->assertSame(200, http_response_code());
     }
+
+    #[Test]
+    public function customOnInvalidExceptionReachesTheExceptionCallbackThroughTheBoundary(): void
+    {
+        $_SERVER['REQUEST_METHOD'] = 'POST';
+        $_SERVER['REQUEST_URI'] = '/signup';
+        $_SERVER['DOCUMENT_ROOT'] = '/nonexistent-docroot';
+        $_POST = ['age' => '5'];
+
+        $caught = [];
+        Router::$exceptionCallback = function (\Throwable $exception) use (&$caught): void {
+            $caught[] = $exception;
+        };
+
+        $finalRan = false;
+        Router::post('/signup', function (StrictSignup $request) use (&$finalRan): void {
+            $finalRan = true;
+        });
+
+        Router::apply('/signup');
+
+        // The Request was built by the container for the final callback and its
+        // custom onInvalid() threw during dependency resolution: the custom type
+        // must arrive intact to the callback, and the final callback must not run.
+        $this->assertCount(1, $caught);
+        $this->assertInstanceOf(RequestRejected::class, $caught[0]);
+        $this->assertSame('The age must be at least 18.', $caught[0]->getMessage());
+        $this->assertSame(400, $caught[0]->getCode(), 'The status channel must survive custom exception types');
+        $this->assertFalse($finalRan, 'A Request that throws during DI resolution must stop the route');
+    }
+}
+
+// phpcs:disable PSR1.Classes.ClassDeclaration.MultipleClasses
+/**
+ * Fixtures locales de la prueba de simetría: un tipo de excepcion propio que
+ * un Request hijo lanza desde su onInvalid() reescrito.
+ */
+final class RequestRejected extends Exception
+{
+}
+
+final class StrictSignup extends Request
+{
+    public function rules(): array
+    {
+        return ['age' => 'required|min:18'];
+    }
+
+    public function onInvalid(string $error): never
+    {
+        throw new RequestRejected($error, 400);
+    }
 }