diff --git a/src/Turbo/CONTRIBUTING.md b/src/Turbo/CONTRIBUTING.md
index ba533f39cb2..6080d68fa7d 100644
--- a/src/Turbo/CONTRIBUTING.md
+++ b/src/Turbo/CONTRIBUTING.md
@@ -7,7 +7,7 @@ Start a Mercure Hub:
         -e MERCURE_PUBLISHER_JWT_KEY='!ChangeMe!' \
         -e MERCURE_SUBSCRIBER_JWT_KEY='!ChangeMe!' \
         -p 3000:3000 \
-        dunglas/mercure caddy run -config /etc/caddy/Caddyfile.dev
+        dunglas/mercure caddy run --config /etc/caddy/Caddyfile.dev
 
 Install the test app:
 
@@ -29,6 +29,7 @@ Start the test app:
 -   `http://localhost:8000/authors`: broadcast
 -   `http://localhost:8000/artists`: broadcast
 -   `http://localhost:8000/songs`: broadcast
+-   `http://localhost:8000/cart_products`: broadcast
 
 ## Run tests
 
diff --git a/src/Turbo/config/services.php b/src/Turbo/config/services.php
index 0cd1e6a1d5f..2c3a95e7e3f 100644
--- a/src/Turbo/config/services.php
+++ b/src/Turbo/config/services.php
@@ -13,9 +13,12 @@
 
 use Symfony\UX\Turbo\Broadcaster\BroadcasterInterface;
 use Symfony\UX\Turbo\Broadcaster\IdAccessor;
+use Symfony\UX\Turbo\Broadcaster\IdFormatter;
 use Symfony\UX\Turbo\Broadcaster\ImuxBroadcaster;
 use Symfony\UX\Turbo\Broadcaster\TwigBroadcaster;
 use Symfony\UX\Turbo\Doctrine\BroadcastListener;
+use Symfony\UX\Turbo\Doctrine\DoctrineClassResolver;
+use Symfony\UX\Turbo\Doctrine\DoctrineIdAccessor;
 use Symfony\UX\Turbo\Twig\TwigExtension;
 
 /*
@@ -29,10 +32,22 @@
 
         ->alias(BroadcasterInterface::class, 'turbo.broadcaster.imux')
 
+        ->set('turbo.doctrine_class_resolver', DoctrineClassResolver::class)
+            ->args([
+                service('doctrine')->nullOnInvalid(),
+            ])
+
+        ->set('turbo.id_formatter', IdFormatter::class)
+
+        ->set('turbo.doctrine_id_accessor', DoctrineIdAccessor::class)
+            ->args([
+                service('doctrine')->nullOnInvalid(),
+            ])
+
         ->set('turbo.id_accessor', IdAccessor::class)
             ->args([
                 service('property_accessor')->nullOnInvalid(),
-                service('doctrine')->nullOnInvalid(),
+                service('turbo.doctrine_id_accessor'),
             ])
 
         ->set('turbo.broadcaster.action_renderer', TwigBroadcaster::class)
@@ -41,6 +56,8 @@
                 service('twig'),
                 abstract_arg('entity template prefixes'),
                 service('turbo.id_accessor'),
+                service('turbo.id_formatter'),
+                service('turbo.doctrine_class_resolver'),
             ])
             ->decorate('turbo.broadcaster.imux')
 
@@ -52,6 +69,8 @@
             ->args([
                 service('turbo.broadcaster.imux'),
                 service('annotation_reader')->nullOnInvalid(),
+                service('turbo.doctrine_id_accessor'),
+                service('turbo.doctrine_class_resolver'),
             ])
             ->tag('doctrine.event_listener', ['event' => 'onFlush'])
             ->tag('doctrine.event_listener', ['event' => 'postFlush'])
diff --git a/src/Turbo/src/Bridge/Mercure/Broadcaster.php b/src/Turbo/src/Bridge/Mercure/Broadcaster.php
index e727a1276db..924a82c51c8 100644
--- a/src/Turbo/src/Bridge/Mercure/Broadcaster.php
+++ b/src/Turbo/src/Bridge/Mercure/Broadcaster.php
@@ -15,7 +15,8 @@
 use Symfony\Component\Mercure\HubInterface;
 use Symfony\Component\Mercure\Update;
 use Symfony\UX\Turbo\Broadcaster\BroadcasterInterface;
-use Symfony\UX\Turbo\Doctrine\ClassUtil;
+use Symfony\UX\Turbo\Broadcaster\IdFormatter;
+use Symfony\UX\Turbo\Doctrine\DoctrineClassResolver;
 
 /**
  * Broadcasts updates rendered using Twig with Mercure.
@@ -42,14 +43,18 @@ final class Broadcaster implements BroadcasterInterface
 
     private $name;
     private $hub;
+    private $idFormatter;
+    private $doctrineClassResolver;
 
     /** @var ExpressionLanguage|null */
     private $expressionLanguage;
 
-    public function __construct(string $name, HubInterface $hub)
+    public function __construct(string $name, HubInterface $hub, ?IdFormatter $idFormatter = null, ?DoctrineClassResolver $doctrineClassResolver = null)
     {
         $this->name = $name;
         $this->hub = $hub;
+        $this->idFormatter = $idFormatter ?? new IdFormatter();
+        $this->doctrineClassResolver = $doctrineClassResolver ?? new DoctrineClassResolver();
 
         if (class_exists(ExpressionLanguage::class)) {
             $this->expressionLanguage = new ExpressionLanguage();
@@ -62,7 +67,7 @@ public function broadcast(object $entity, string $action, array $options): void
             return;
         }
 
-        $entityClass = ClassUtil::getEntityClass($entity);
+        $entityClass = $this->doctrineClassResolver->resolve($entity);
 
         if (!isset($options['rendered_action'])) {
             throw new \InvalidArgumentException(sprintf('Cannot broadcast entity of class "%s" as option "rendered_action" is missing.', $entityClass));
@@ -99,7 +104,9 @@ public function broadcast(object $entity, string $action, array $options): void
                 throw new \InvalidArgumentException(sprintf('Cannot broadcast entity of class "%s": the option "topics" is empty and "id" is missing.', $entityClass));
             }
 
-            $options['topics'] = (array) sprintf(self::TOPIC_PATTERN, rawurlencode($entityClass), rawurlencode(implode('-', (array) $options['id'])));
+            $id = $this->idFormatter->format($options['id']);
+
+            $options['topics'] = (array) sprintf(self::TOPIC_PATTERN, rawurlencode($entityClass), rawurlencode($id));
         }
 
         $update = new Update(
diff --git a/src/Turbo/src/Bridge/Mercure/TurboStreamListenRenderer.php b/src/Turbo/src/Bridge/Mercure/TurboStreamListenRenderer.php
index 97dd22b76e7..d86e7032434 100644
--- a/src/Turbo/src/Bridge/Mercure/TurboStreamListenRenderer.php
+++ b/src/Turbo/src/Bridge/Mercure/TurboStreamListenRenderer.php
@@ -14,6 +14,8 @@
 use Symfony\Component\Mercure\HubInterface;
 use Symfony\UX\StimulusBundle\Helper\StimulusHelper;
 use Symfony\UX\Turbo\Broadcaster\IdAccessor;
+use Symfony\UX\Turbo\Broadcaster\IdFormatter;
+use Symfony\UX\Turbo\Doctrine\DoctrineClassResolver;
 use Symfony\UX\Turbo\Twig\TurboStreamListenRendererInterface;
 use Symfony\WebpackEncoreBundle\Twig\StimulusTwigExtension;
 use Twig\Environment;
@@ -28,14 +30,18 @@ final class TurboStreamListenRenderer implements TurboStreamListenRendererInterf
     private HubInterface $hub;
     private StimulusHelper $stimulusHelper;
     private IdAccessor $idAccessor;
+    private IdFormatter $idFormatter;
+    private DoctrineClassResolver $doctrineClassResolver;
 
     /**
      * @param $stimulus StimulusHelper
      */
-    public function __construct(HubInterface $hub, StimulusHelper|StimulusTwigExtension $stimulus, IdAccessor $idAccessor)
+    public function __construct(HubInterface $hub, StimulusHelper|StimulusTwigExtension $stimulus, IdAccessor $idAccessor, ?IdFormatter $idFormatter = null, ?DoctrineClassResolver $doctrineClassResolver = null)
     {
         $this->hub = $hub;
         $this->idAccessor = $idAccessor;
+        $this->idFormatter = $idFormatter ?? new IdFormatter();
+        $this->doctrineClassResolver = $doctrineClassResolver ?? new DoctrineClassResolver();
 
         if ($stimulus instanceof StimulusTwigExtension) {
             trigger_deprecation('symfony/ux-turbo', '2.9', 'Passing an instance of "%s" as second argument of "%s" is deprecated, pass an instance of "%s" instead.', StimulusTwigExtension::class, __CLASS__, StimulusHelper::class);
@@ -49,13 +55,15 @@ public function __construct(HubInterface $hub, StimulusHelper|StimulusTwigExtens
     public function renderTurboStreamListen(Environment $env, $topic): string
     {
         if (\is_object($topic)) {
-            $class = $topic::class;
+            $class = $this->doctrineClassResolver->resolve($topic);
 
             if (!$id = $this->idAccessor->getEntityId($topic)) {
                 throw new \LogicException(sprintf('Cannot listen to entity of class "%s" as the PropertyAccess component is not installed. Try running "composer require symfony/property-access".', $class));
             }
 
-            $topic = sprintf(Broadcaster::TOPIC_PATTERN, rawurlencode($class), rawurlencode(implode('-', $id)));
+            $formattedId = $this->idFormatter->format($id);
+
+            $topic = sprintf(Broadcaster::TOPIC_PATTERN, rawurlencode($class), rawurlencode($formattedId));
         } elseif (!preg_match('/[^a-zA-Z0-9_\x7f-\xff\\\\]/', $topic) && class_exists($topic)) {
             // Generate a URI template to subscribe to updates for all objects of this class
             $topic = sprintf(Broadcaster::TOPIC_PATTERN, rawurlencode($topic), '{id}');
diff --git a/src/Turbo/src/Broadcaster/BroadcasterInterface.php b/src/Turbo/src/Broadcaster/BroadcasterInterface.php
index 7bff8a1e20f..fb89534c757 100644
--- a/src/Turbo/src/Broadcaster/BroadcasterInterface.php
+++ b/src/Turbo/src/Broadcaster/BroadcasterInterface.php
@@ -19,7 +19,7 @@
 interface BroadcasterInterface
 {
     /**
-     * @param array{id?: string|string[], transports?: string|string[], topics?: string|string[], template?: string, rendered_action?: string, private?: bool, sse_id?: string, sse_type?: string, sse_retry?: int} $options
+     * @param array{id?: array<string, string>|array<string, array<string, string>>, transports?: string|string[], topics?: string|string[], template?: string, rendered_action?: string, private?: bool, sse_id?: string, sse_type?: string, sse_retry?: int} $options
      */
     public function broadcast(object $entity, string $action, array $options): void;
 }
diff --git a/src/Turbo/src/Broadcaster/IdAccessor.php b/src/Turbo/src/Broadcaster/IdAccessor.php
index 64606947fdf..27087eff625 100644
--- a/src/Turbo/src/Broadcaster/IdAccessor.php
+++ b/src/Turbo/src/Broadcaster/IdAccessor.php
@@ -11,30 +11,28 @@
 
 namespace Symfony\UX\Turbo\Broadcaster;
 
-use Doctrine\Persistence\ManagerRegistry;
 use Symfony\Component\PropertyAccess\PropertyAccess;
 use Symfony\Component\PropertyAccess\PropertyAccessorInterface;
+use Symfony\UX\Turbo\Doctrine\DoctrineIdAccessor;
 
 class IdAccessor
 {
     private $propertyAccessor;
-    private $doctrine;
+    private $doctrineIdAccessor;
 
-    public function __construct(?PropertyAccessorInterface $propertyAccessor = null, ?ManagerRegistry $doctrine = null)
+    public function __construct(?PropertyAccessorInterface $propertyAccessor = null, ?DoctrineIdAccessor $doctrineIdAccessor = null)
     {
         $this->propertyAccessor = $propertyAccessor ?? (class_exists(PropertyAccess::class) ? PropertyAccess::createPropertyAccessor() : null);
-        $this->doctrine = $doctrine;
+        $this->doctrineIdAccessor = $doctrineIdAccessor ?? new DoctrineIdAccessor();
     }
 
     /**
-     * @return string[]
+     * @return array<string, array<string, string>>|array<string, string>|null
      */
     public function getEntityId(object $entity): ?array
     {
-        $entityClass = $entity::class;
-
-        if ($this->doctrine && $em = $this->doctrine->getManagerForClass($entityClass)) {
-            return $em->getClassMetadata($entityClass)->getIdentifierValues($entity);
+        if (null !== ($id = $this->doctrineIdAccessor->getEntityId($entity))) {
+            return $id;
         }
 
         if ($this->propertyAccessor) {
diff --git a/src/Turbo/src/Broadcaster/IdFormatter.php b/src/Turbo/src/Broadcaster/IdFormatter.php
new file mode 100644
index 00000000000..04834fc5143
--- /dev/null
+++ b/src/Turbo/src/Broadcaster/IdFormatter.php
@@ -0,0 +1,41 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\UX\Turbo\Broadcaster;
+
+/**
+ * Formats an id array to a string.
+ *
+ * In defaults the id array is something like `['id' => 1]` or `['uuid' => '00000000-0000-0000-0000-000000000000']`.
+ * For a composite key it could be something like `['cart' => ['id' => 1], 'product' => ['id' => 1]]`.
+ *
+ * To create a string representation of the id, the values of the array are flattened and concatenated with a dash.
+ *
+ * @author Jason Schilling <jason@sourecode.dev>
+ */
+class IdFormatter
+{
+    /**
+     * @param array<string, array<string, string>>|array<string, string>|string $id
+     */
+    public function format(array|string $id): string
+    {
+        if (\is_string($id)) {
+            return $id;
+        }
+
+        $flatten = [];
+
+        array_walk_recursive($id, static function ($item) use (&$flatten) { $flatten[] = $item; });
+
+        return implode('-', $flatten);
+    }
+}
diff --git a/src/Turbo/src/Broadcaster/TwigBroadcaster.php b/src/Turbo/src/Broadcaster/TwigBroadcaster.php
index 05a428cd53f..f79d7428bcf 100644
--- a/src/Turbo/src/Broadcaster/TwigBroadcaster.php
+++ b/src/Turbo/src/Broadcaster/TwigBroadcaster.php
@@ -11,7 +11,7 @@
 
 namespace Symfony\UX\Turbo\Broadcaster;
 
-use Symfony\UX\Turbo\Doctrine\ClassUtil;
+use Symfony\UX\Turbo\Doctrine\DoctrineClassResolver;
 use Twig\Environment;
 
 /**
@@ -25,16 +25,20 @@ final class TwigBroadcaster implements BroadcasterInterface
     private $twig;
     private $templatePrefixes;
     private $idAccessor;
+    private $idFormatter;
+    private $doctrineClassResolver;
 
     /**
      * @param array<string, string> $templatePrefixes
      */
-    public function __construct(BroadcasterInterface $broadcaster, Environment $twig, array $templatePrefixes = [], ?IdAccessor $idAccessor = null)
+    public function __construct(BroadcasterInterface $broadcaster, Environment $twig, array $templatePrefixes = [], ?IdAccessor $idAccessor = null, ?IdFormatter $idFormatter = null, ?DoctrineClassResolver $doctrineClassResolver = null)
     {
         $this->broadcaster = $broadcaster;
         $this->twig = $twig;
         $this->templatePrefixes = $templatePrefixes;
         $this->idAccessor = $idAccessor ?? new IdAccessor();
+        $this->idFormatter = $idFormatter ?? new IdFormatter();
+        $this->doctrineClassResolver = $doctrineClassResolver ?? new DoctrineClassResolver();
     }
 
     public function broadcast(object $entity, string $action, array $options): void
@@ -43,10 +47,9 @@ public function broadcast(object $entity, string $action, array $options): void
             $options['id'] = $id;
         }
 
-        $class = ClassUtil::getEntityClass($entity);
-
         if (null === $template = $options['template'] ?? null) {
-            $template = $class;
+            $template = $this->doctrineClassResolver->resolve($entity);
+
             foreach ($this->templatePrefixes as $namespace => $prefix) {
                 if (str_starts_with($template, $namespace)) {
                     $template = substr_replace($template, $prefix, 0, \strlen($namespace));
@@ -63,7 +66,7 @@ public function broadcast(object $entity, string $action, array $options): void
             ->renderBlock($action, [
                 'entity' => $entity,
                 'action' => $action,
-                'id' => implode('-', (array) ($options['id'] ?? [])),
+                'id' => $this->idFormatter->format($options['id'] ?? []),
             ] + $options);
 
         $this->broadcaster->broadcast($entity, $action, $options);
diff --git a/src/Turbo/src/Doctrine/BroadcastListener.php b/src/Turbo/src/Doctrine/BroadcastListener.php
index c2c07eb0c9d..44009237d4f 100644
--- a/src/Turbo/src/Doctrine/BroadcastListener.php
+++ b/src/Turbo/src/Doctrine/BroadcastListener.php
@@ -29,6 +29,8 @@ final class BroadcastListener implements ResetInterface
 {
     private $broadcaster;
     private $annotationReader;
+    private $doctrineIdAccessor;
+    private $doctrineClassResolver;
 
     /**
      * @var array<class-string, array<mixed>>
@@ -48,12 +50,14 @@ final class BroadcastListener implements ResetInterface
      */
     private $removedEntities;
 
-    public function __construct(BroadcasterInterface $broadcaster, ?Reader $annotationReader = null)
+    public function __construct(BroadcasterInterface $broadcaster, ?Reader $annotationReader = null, ?DoctrineIdAccessor $doctrineIdAccessor = null, ?DoctrineClassResolver $doctrineClassResolver = null)
     {
         $this->reset();
 
         $this->broadcaster = $broadcaster;
         $this->annotationReader = $annotationReader;
+        $this->doctrineIdAccessor = $doctrineIdAccessor ?? new DoctrineIdAccessor();
+        $this->doctrineClassResolver = $doctrineClassResolver ?? new DoctrineClassResolver();
     }
 
     /**
@@ -94,7 +98,7 @@ public function postFlush(EventArgs $eventArgs): void
         try {
             foreach ($this->createdEntities as $entity) {
                 $options = $this->createdEntities[$entity];
-                $id = $em->getClassMetadata($entity::class)->getIdentifierValues($entity);
+                $id = $this->doctrineIdAccessor->getEntityId($entity, $em);
                 foreach ($options as $option) {
                     $option['id'] = $id;
                     $this->broadcaster->broadcast($entity, Broadcast::ACTION_CREATE, $option);
@@ -126,28 +130,28 @@ public function reset(): void
 
     private function storeEntitiesToPublish(EntityManagerInterface $em, object $entity, string $property): void
     {
-        $class = ClassUtil::getEntityClass($entity);
+        $entityClass = $this->doctrineClassResolver->resolve($entity, $em);
 
-        if (!isset($this->broadcastedClasses[$class])) {
-            $this->broadcastedClasses[$class] = [];
-            $r = new \ReflectionClass($class);
+        if (!isset($this->broadcastedClasses[$entityClass])) {
+            $this->broadcastedClasses[$entityClass] = [];
+            $r = new \ReflectionClass($entityClass);
 
             if ($options = $r->getAttributes(Broadcast::class)) {
                 foreach ($options as $option) {
-                    $this->broadcastedClasses[$class][] = $option->newInstance()->options;
+                    $this->broadcastedClasses[$entityClass][] = $option->newInstance()->options;
                 }
             } elseif ($this->annotationReader && $options = $this->annotationReader->getClassAnnotations($r)) {
                 foreach ($options as $option) {
                     if ($option instanceof Broadcast) {
-                        $this->broadcastedClasses[$class][] = $option->options;
+                        $this->broadcastedClasses[$entityClass][] = $option->options;
                     }
                 }
             }
         }
 
-        if ($options = $this->broadcastedClasses[$class]) {
+        if ($options = $this->broadcastedClasses[$entityClass]) {
             if ('createdEntities' !== $property) {
-                $id = $em->getClassMetadata($class)->getIdentifierValues($entity);
+                $id = $this->doctrineIdAccessor->getEntityId($entity, $em);
                 foreach ($options as $k => $option) {
                     $options[$k]['id'] = $id;
                 }
diff --git a/src/Turbo/src/Doctrine/DoctrineClassResolver.php b/src/Turbo/src/Doctrine/DoctrineClassResolver.php
new file mode 100644
index 00000000000..f5869f4b8c4
--- /dev/null
+++ b/src/Turbo/src/Doctrine/DoctrineClassResolver.php
@@ -0,0 +1,55 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\UX\Turbo\Doctrine;
+
+use Doctrine\ORM\Mapping\ClassMetadata;
+use Doctrine\Persistence\ManagerRegistry;
+use Doctrine\Persistence\ObjectManager;
+
+/**
+ * @author Jason Schilling <jason@sourecode.dev>
+ */
+class DoctrineClassResolver
+{
+    private $doctrine;
+
+    public function __construct(?ManagerRegistry $doctrine = null)
+    {
+        $this->doctrine = $doctrine;
+    }
+
+    /**
+     * @return class-string
+     */
+    public function resolve(object $entity, ?ObjectManager $em = null): string
+    {
+        $class = ClassUtil::getEntityClass($entity);
+
+        if (!$this->doctrine) {
+            return $class;
+        }
+
+        $em = $em ?? $this->doctrine->getManagerForClass($class);
+
+        if (!$em) {
+            return $class;
+        }
+
+        $classMetadata = $em->getClassMetadata($class);
+
+        if ($classMetadata instanceof ClassMetadata) {
+            return $classMetadata->rootEntityName;
+        }
+
+        return $class;
+    }
+}
diff --git a/src/Turbo/src/Doctrine/DoctrineIdAccessor.php b/src/Turbo/src/Doctrine/DoctrineIdAccessor.php
new file mode 100644
index 00000000000..b1a5edbd03f
--- /dev/null
+++ b/src/Turbo/src/Doctrine/DoctrineIdAccessor.php
@@ -0,0 +1,58 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\UX\Turbo\Doctrine;
+
+use Doctrine\Persistence\ManagerRegistry;
+use Doctrine\Persistence\ObjectManager;
+
+/**
+ * @author Jason Schilling <jason@sourecode.dev>
+ */
+class DoctrineIdAccessor
+{
+    private $doctrine;
+
+    public function __construct(?ManagerRegistry $doctrine = null)
+    {
+        $this->doctrine = $doctrine;
+    }
+
+    /**
+     * @return array<string, array<string, string>>|array<string, string>|null
+     */
+    public function getEntityId(object $entity, ?ObjectManager $em = null): ?array
+    {
+        $em = $em ?? $this->doctrine?->getManagerForClass($entity::class);
+
+        if ($em) {
+            return $this->getIdentifierValues($em, $entity);
+        }
+
+        return null;
+    }
+
+    /**
+     * @return array<string, string>|array<string, array<string, string>>
+     */
+    private function getIdentifierValues(ObjectManager $em, object $entity): array
+    {
+        $values = $em->getClassMetadata($entity::class)->getIdentifierValues($entity);
+
+        foreach ($values as $key => $value) {
+            if (\is_object($value)) {
+                $values[$key] = $this->getIdentifierValues($em, $value);
+            }
+        }
+
+        return $values;
+    }
+}
diff --git a/src/Turbo/src/TurboBundle.php b/src/Turbo/src/TurboBundle.php
index 61542a4bab9..99cbf74a6ad 100644
--- a/src/Turbo/src/TurboBundle.php
+++ b/src/Turbo/src/TurboBundle.php
@@ -14,6 +14,7 @@
 use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
 use Symfony\Component\DependencyInjection\Compiler\PassConfig;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Reference;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpKernel\Bundle\Bundle;
 
@@ -45,6 +46,24 @@ public function process(ContainerBuilder $container): void
                 }
             }
         }, PassConfig::TYPE_BEFORE_REMOVING);
+
+        $container->addCompilerPass(new class() implements CompilerPassInterface {
+            public function process(ContainerBuilder $container): void
+            {
+                $serviceIds = [
+                    ...$container->findTaggedServiceIds('turbo.broadcaster'),
+                    ...$container->findTaggedServiceIds('turbo.renderer.stream_listen'),
+                ];
+
+                foreach ($serviceIds as $serviceId => $tags) {
+                    $definition = $container->getDefinition($serviceId);
+
+                    $definition
+                        ->addArgument(new Reference('turbo.id_formatter'))
+                        ->addArgument(new Reference('turbo.doctrine_class_resolver'));
+                }
+            }
+        });
     }
 
     public function getPath(): string
diff --git a/src/Turbo/tests/BroadcastTest.php b/src/Turbo/tests/BroadcastTest.php
index ea57faf7628..53cc43317a0 100644
--- a/src/Turbo/tests/BroadcastTest.php
+++ b/src/Turbo/tests/BroadcastTest.php
@@ -27,7 +27,7 @@ class BroadcastTest extends PantherTestCase
     protected function setUp(): void
     {
         if (!file_exists(__DIR__.'/app/public/build')) {
-            throw new \Exception(sprintf('Move into %s and execute Encore before running this test.', realpath(__DIR__.'/app')));
+            throw new \Exception(sprintf('Move into "%s" and execute Encore before running this test.', realpath(__DIR__.'/app')));
         }
 
         parent::setUp();
@@ -104,4 +104,19 @@ public function testBroadcastWithProxy(): void
         // this part is from the stream template
         $this->assertSelectorWillContain('#artists', ', updated)');
     }
+
+    public function testBroadcastWithCompositePrimaryKey(): void
+    {
+        ($client = self::createPantherClient())->request('GET', '/cartProducts');
+
+        // submit first to create the entities
+        $client->submitForm('Submit', ['title' => 'product 1']);
+        $this->assertSelectorWillContain('#cart_products', 'product 1');
+
+        // submit again to update the quantity
+        $client->submitForm('Submit');
+        $this->assertSelectorWillContain('#cart_products', '2x product 1');
+        // this part is from the stream template
+        $this->assertSelectorWillContain('#cart_products', ', updated)');
+    }
 }
diff --git a/src/Turbo/tests/app/Entity/Cart.php b/src/Turbo/tests/app/Entity/Cart.php
new file mode 100644
index 00000000000..f3741082d4d
--- /dev/null
+++ b/src/Turbo/tests/app/Entity/Cart.php
@@ -0,0 +1,27 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Entity;
+
+use Doctrine\DBAL\Types\Types;
+use Doctrine\ORM\Mapping as ORM;
+
+/**
+ * @author Jason Schilling <jason@sourecode.dev>
+ */
+#[ORM\Entity]
+class Cart
+{
+    #[ORM\Id]
+    #[ORM\GeneratedValue(strategy: 'AUTO')]
+    #[ORM\Column(type: Types::INTEGER)]
+    public ?int $id = null;
+}
diff --git a/src/Turbo/tests/app/Entity/CartProduct.php b/src/Turbo/tests/app/Entity/CartProduct.php
new file mode 100644
index 00000000000..dbd8b283630
--- /dev/null
+++ b/src/Turbo/tests/app/Entity/CartProduct.php
@@ -0,0 +1,37 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Entity;
+
+use Doctrine\DBAL\Types\Types;
+use Doctrine\ORM\Mapping as ORM;
+use Symfony\UX\Turbo\Attribute\Broadcast;
+
+/**
+ * @author Jason Schilling <jason@sourecode.dev>
+ */
+#[Broadcast]
+#[ORM\Entity]
+class CartProduct
+{
+    #[ORM\Id]
+    #[ORM\ManyToOne(targetEntity: Cart::class)]
+    #[ORM\JoinColumn(nullable: false, onDelete: 'CASCADE')]
+    public ?Cart $cart = null;
+
+    #[ORM\Id]
+    #[ORM\ManyToOne(targetEntity: Product::class)]
+    #[ORM\JoinColumn(nullable: false, onDelete: 'CASCADE')]
+    public ?Product $product = null;
+
+    #[ORM\Column(type: Types::INTEGER)]
+    public int $quantity = 1;
+}
diff --git a/src/Turbo/tests/app/Entity/Product.php b/src/Turbo/tests/app/Entity/Product.php
new file mode 100644
index 00000000000..599a2cfa903
--- /dev/null
+++ b/src/Turbo/tests/app/Entity/Product.php
@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Entity;
+
+use Doctrine\DBAL\Types\Types;
+use Doctrine\ORM\Mapping as ORM;
+
+/**
+ * @author Jason Schilling <jason@sourecode.dev>
+ */
+#[ORM\Entity]
+class Product
+{
+    #[ORM\Id]
+    #[ORM\GeneratedValue(strategy: 'AUTO')]
+    #[ORM\Column(type: Types::INTEGER)]
+    public ?int $id = null;
+
+    #[ORM\Column]
+    public string $title = '';
+}
diff --git a/src/Turbo/tests/app/Entity/Song.php b/src/Turbo/tests/app/Entity/Song.php
index cdb5d8a5ef8..6600f2121ea 100644
--- a/src/Turbo/tests/app/Entity/Song.php
+++ b/src/Turbo/tests/app/Entity/Song.php
@@ -24,7 +24,7 @@ class Song
     #[ORM\Id]
     #[ORM\GeneratedValue(strategy: 'AUTO')]
     #[ORM\Column(type: 'integer')]
-    public ?string $id = null;
+    public ?int $id = null;
 
     #[ORM\Column]
     public string $title = '';
diff --git a/src/Turbo/tests/app/Kernel.php b/src/Turbo/tests/app/Kernel.php
index 078ba8da579..5d99852c3e6 100644
--- a/src/Turbo/tests/app/Kernel.php
+++ b/src/Turbo/tests/app/Kernel.php
@@ -13,6 +13,9 @@
 
 use App\Entity\Artist;
 use App\Entity\Book;
+use App\Entity\Cart;
+use App\Entity\CartProduct;
+use App\Entity\Product;
 use App\Entity\Song;
 use Composer\InstalledVersions;
 use Doctrine\Bundle\DoctrineBundle\DoctrineBundle;
@@ -137,6 +140,7 @@ protected function configureRoutes(RoutingConfigurator $routes): void
         $routes->add('artists', '/artists')->controller('kernel::artists');
         $routes->add('artist', '/artists/{id}')->controller('kernel::artist');
         $routes->add('artist_from_song', '/artistFromSong')->controller('kernel::artistFromSong');
+        $routes->add('cart_products', '/cartProducts')->controller('kernel::cartProducts');
     }
 
     public function getProjectDir(): string
@@ -305,4 +309,58 @@ public function artistFromSong(Request $request, EntityManagerInterface $doctrin
             'song' => $song,
         ]));
     }
+
+    public function cartProducts(Request $request, EntityManagerInterface $doctrine, Environment $twig): Response
+    {
+        $cartProduct = null;
+        if ($request->isMethod('POST')) {
+            $cartId = $request->get('cartId');
+            $productId = $request->get('productId');
+
+            if (!$cartId || !$productId) {
+                $cart = new Cart();
+                $product = new Product();
+
+                if ($title = $request->get('title')) {
+                    $product->title = $title;
+                }
+
+                $cartProduct = new CartProduct();
+                $cartProduct->cart = $cart;
+                $cartProduct->product = $product;
+                $cartProduct->quantity = 1;
+
+                $doctrine->persist($cart);
+                $doctrine->persist($product);
+                $doctrine->persist($cartProduct);
+                $doctrine->flush();
+            } else {
+                $cartProduct = $doctrine->find(CartProduct::class, ['cart' => $cartId, 'product' => $productId]);
+
+                if (!$cartProduct) {
+                    throw new NotFoundHttpException();
+                }
+
+                ++$cartProduct->quantity;
+
+                if ($remove = $request->get('remove')) {
+                    $doctrine->remove($cartProduct);
+                    if ($cartProduct->product) {
+                        $doctrine->remove($cartProduct->product); // for cleanup
+                    }
+                    if ($cartProduct->cart) {
+                        $doctrine->remove($cartProduct->cart); // for cleanup
+                    }
+                } else {
+                    $doctrine->persist($cartProduct);
+                }
+
+                $doctrine->flush();
+            }
+        }
+
+        return new Response($twig->render('cart_products.html.twig', [
+            'cartProduct' => $cartProduct,
+        ]));
+    }
 }
diff --git a/src/Turbo/tests/app/templates/base.html.twig b/src/Turbo/tests/app/templates/base.html.twig
index 0a3c7a37350..96b3a07f3de 100644
--- a/src/Turbo/tests/app/templates/base.html.twig
+++ b/src/Turbo/tests/app/templates/base.html.twig
@@ -14,6 +14,7 @@
                 <li><a href="{{ path('books') }}">Books (broadcast)</a></li>
                 <li><a href="{{ path('songs') }}">Songs (broadcast)</a></li>
                 <li><a href="{{ path('artists') }}">Artists (broadcast)</a></li>
+                <li><a href="{{ path('cart_products') }}">CartProducts (broadcast)</a></li>
             </ul>
         </nav>
 
diff --git a/src/Turbo/tests/app/templates/broadcast/CartProduct.stream.html.twig b/src/Turbo/tests/app/templates/broadcast/CartProduct.stream.html.twig
new file mode 100644
index 00000000000..9f285aa3fe0
--- /dev/null
+++ b/src/Turbo/tests/app/templates/broadcast/CartProduct.stream.html.twig
@@ -0,0 +1,20 @@
+
+{% block create %}
+    <turbo-stream action="append" target="cart_products">
+        <template>
+            <div id="{{ 'cart_product_' ~ id }}">{{ entity.quantity }}x {{ entity.product.title }} (cart: {{ entity.cart.id }}, product: {{ entity.product.id }})</div>
+        </template>
+    </turbo-stream>
+{% endblock %}
+
+{% block update %}
+    <turbo-stream action="update" target="{{ 'cart_product_' ~ id }}">
+        <template>
+            {{ entity.quantity }}x {{ entity.product.title }} (cart: {{ entity.cart.id }}, product: {{ entity.product.id }}, updated)
+        </template>
+    </turbo-stream>
+{% endblock %}
+
+{% block remove %}
+    <turbo-stream action="remove" target="{{ 'cart_product_' ~ id }}"></turbo-stream>
+{% endblock %}
diff --git a/src/Turbo/tests/app/templates/cart_products.html.twig b/src/Turbo/tests/app/templates/cart_products.html.twig
new file mode 100644
index 00000000000..be22c298d5d
--- /dev/null
+++ b/src/Turbo/tests/app/templates/cart_products.html.twig
@@ -0,0 +1,17 @@
+{% extends 'base.html.twig' %}
+
+{% block body %}
+    <h1>Create Cart, Product and CartProduct, increase quantity on update</h1>
+
+    <div id="cart_products" {{ turbo_stream_listen('App\\Entity\\CartProduct') }}></div>
+
+    <turbo-frame id="api">
+        <form method="post" enctype="application/x-www-form-urlencoded">
+            <input placeholder="Title" name="title">
+            <input placeholder="Cart ID" name="cartId" value="{{ cartProduct ? cartProduct.cart.id }}">
+            <input placeholder="Product ID" name="productId" value="{{ cartProduct ? cartProduct.product.id }}">
+            <label><input type="checkbox" name="remove" value="remove"> Remove</label>
+            <button>Submit</button>
+        </form>
+    </turbo-frame>
+{% endblock %}