fix(http): cleanup session flash values

packages/router/src/HttpApplication.php

@@ -10,7 +10,7 @@
 use Tempest\Core\Kernel;
 use Tempest\Core\Tempest;
 use Tempest\Http\RequestFactory;
-use Tempest\Http\Session\SessionManager;
+use Tempest\Http\Session\Session;
 use Tempest\Log\Channels\AppendLogChannel;
 use Tempest\Log\LogConfig;
 
@@ -57,7 +57,7 @@ public function run(): void
             $router->dispatch($psrRequest),
         );
 
-        $this->container->get(SessionManager::class)->cleanup();
+        $this->container->get(Session::class)->cleanup();
 
         $this->container->get(Kernel::class)->shutdown();
     }

tests/Fixtures/Controllers/ControllerWithSession.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Tests\Tempest\Fixtures\Controllers;
+
+use Tempest\Http\Responses\Ok;
+use Tempest\Http\Session\Session;
+use Tempest\Router\Get;
+
+final class ControllerWithSession
+{
+    #[Get('/controller-with-session')]
+    public function __invoke(Session $session): Ok
+    {
+        $session->flash('test', 'hi');
+
+        return new Ok();
+    }
+}

tests/Fixtures/Controllers/ControllerWithoutSession.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace Tests\Tempest\Fixtures\Controllers;
+
+use Tempest\Http\Responses\Ok;
+use Tempest\Router\Get;
+use Tempest\Router\Stateless;
+
+final class ControllerWithoutSession
+{
+    #[Stateless, Get('/controller-without-session')]
+    public function __invoke(): Ok
+    {
+        return new Ok();
+    }
+}

tests/Integration/Application/HttpApplicationTest.php

@@ -4,8 +4,16 @@
 
 namespace Tests\Tempest\Integration\Application;
 
+use PHPUnit\Framework\Attributes\Test;
+use Symfony\Component\Process\Process;
+use Tempest\HttpClient\HttpClient;
+use Tests\Tempest\Fixtures\Controllers\ControllerWithoutSession;
+use Tests\Tempest\Fixtures\Controllers\ControllerWithSession;
 use Tests\Tempest\Integration\FrameworkIntegrationTestCase;
 
+use function Tempest\Router\uri;
+use function Tempest\Support\arr;
+
 /**
  * @internal
  */
@@ -17,4 +25,29 @@ public function test_http_application_run(): void
             ->get('/')
             ->assertOk();
     }
+
+    #[Test]
+    public function session_is_not_set_even_when_it_was_cleaned_and_empty(): void
+    {
+        $this->appConfig->baseUri = 'http://127.0.0.1:8081';
+        $process = new Process(['./tempest', 'serve', '127.0.0.1:8081'], getcwd());
+        $process->start();
+        usleep(200_000);
+
+        $client = $this->get(HttpClient::class);
+
+        $response = $client->get(uri(ControllerWithoutSession::class));
+        $cookies = arr($response->getHeader('set-cookie')->values ?? [])
+            ->map(fn (string $cookie) => explode('=', $cookie)[0]);
+
+        $this->assertFalse($cookies->contains('tempest_session_id'));
+
+        $response = $client->get(uri(ControllerWithSession::class));
+        $cookies = arr($response->getHeader('set-cookie')->values ?? [])
+            ->map(fn (string $cookie) => explode('=', $cookie)[0]);
+
+        $this->assertTrue($cookies->contains('tempest_session_id'));
+
+        $process->stop();
+    }
 }

tests/Integration/Http/RedisSessionTest.php

@@ -29,6 +29,10 @@ protected function setUp(): void
     {
         parent::setUp();
 
+        if (! extension_loaded('redis') || ! class_exists(\Redis::class)) {
+            $this->markTestSkipped('The `redis` extension is not loaded.');
+        }
+
         $this->container->config(new RedisSessionConfig(expiration: Duration::hours(2), prefix: 'test_session:'));
         $this->container->singleton(
             SessionManager::class,