diff --git a/src/agent/tests/InputTest.php b/src/agent/tests/InputTest.php
new file mode 100644
index 000000000..45f2c5541
--- /dev/null
+++ b/src/agent/tests/InputTest.php
@@ -0,0 +1,123 @@
+<?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\AI\Agent\Tests;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\AI\Agent\Input;
+use Symfony\AI\Platform\Message\Message;
+use Symfony\AI\Platform\Message\MessageBag;
+
+final class InputTest extends TestCase
+{
+    public function testConstructorSetsProperties()
+    {
+        $messageBag = new MessageBag();
+        $options = ['temperature' => 0.7, 'max_tokens' => 100];
+
+        $input = new Input('gpt-4', $messageBag, $options);
+
+        $this->assertSame('gpt-4', $input->getModel());
+        $this->assertSame($messageBag, $input->getMessageBag());
+        $this->assertSame($options, $input->getOptions());
+    }
+
+    public function testConstructorWithDefaultOptions()
+    {
+        $messageBag = new MessageBag();
+
+        $input = new Input('claude-3', $messageBag);
+
+        $this->assertSame('claude-3', $input->getModel());
+        $this->assertSame($messageBag, $input->getMessageBag());
+        $this->assertSame([], $input->getOptions());
+    }
+
+    public function testGetModel()
+    {
+        $messageBag = new MessageBag();
+        $input = new Input('test-model', $messageBag);
+
+        $this->assertSame('test-model', $input->getModel());
+    }
+
+    public function testSetModel()
+    {
+        $messageBag = new MessageBag();
+        $input = new Input('original-model', $messageBag);
+
+        $input->setModel('new-model');
+
+        $this->assertSame('new-model', $input->getModel());
+    }
+
+    public function testGetMessageBag()
+    {
+        $messageBag = new MessageBag();
+        $messageBag->add(Message::ofUser('Hello'));
+
+        $input = new Input('model', $messageBag);
+
+        $result = $input->getMessageBag();
+
+        $this->assertSame($messageBag, $result);
+        $this->assertCount(1, $result);
+    }
+
+    public function testSetMessageBag()
+    {
+        $originalMessageBag = new MessageBag();
+        $input = new Input('model', $originalMessageBag);
+
+        $newMessageBag = new MessageBag();
+        $newMessageBag->add(Message::ofUser('New message'));
+
+        $input->setMessageBag($newMessageBag);
+
+        $result = $input->getMessageBag();
+        $this->assertSame($newMessageBag, $result);
+        $this->assertCount(1, $result);
+    }
+
+    public function testGetOptions()
+    {
+        $messageBag = new MessageBag();
+        $options = ['foo' => 'bar', 'baz' => 42];
+
+        $input = new Input('model', $messageBag, $options);
+
+        $this->assertSame($options, $input->getOptions());
+    }
+
+    public function testSetOptions()
+    {
+        $messageBag = new MessageBag();
+        $input = new Input('model', $messageBag, ['old' => 'option']);
+
+        $newOptions = ['new' => 'options', 'count' => 3];
+        $input->setOptions($newOptions);
+
+        $this->assertSame($newOptions, $input->getOptions());
+    }
+
+    public function testSetOptionsReplacesAllOptions()
+    {
+        $messageBag = new MessageBag();
+        $input = new Input('model', $messageBag, ['a' => 1, 'b' => 2]);
+
+        $input->setOptions(['c' => 3]);
+
+        $options = $input->getOptions();
+        $this->assertArrayHasKey('c', $options);
+        $this->assertArrayNotHasKey('a', $options);
+        $this->assertArrayNotHasKey('b', $options);
+    }
+}
diff --git a/src/agent/tests/OutputTest.php b/src/agent/tests/OutputTest.php
new file mode 100644
index 000000000..f48229935
--- /dev/null
+++ b/src/agent/tests/OutputTest.php
@@ -0,0 +1,146 @@
+<?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\AI\Agent\Tests;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\AI\Agent\Output;
+use Symfony\AI\Platform\Message\Message;
+use Symfony\AI\Platform\Message\MessageBag;
+use Symfony\AI\Platform\Result\TextResult;
+
+final class OutputTest extends TestCase
+{
+    public function testConstructorSetsProperties()
+    {
+        $messageBag = new MessageBag();
+        $result = new TextResult('Test content');
+        $options = ['temperature' => 0.5];
+
+        $output = new Output('gpt-4', $result, $messageBag, $options);
+
+        $this->assertSame('gpt-4', $output->getModel());
+        $this->assertSame($result, $output->getResult());
+        $this->assertSame($messageBag, $output->getMessageBag());
+        $this->assertSame($options, $output->getOptions());
+    }
+
+    public function testConstructorWithDefaultOptions()
+    {
+        $messageBag = new MessageBag();
+        $result = new TextResult('Content');
+
+        $output = new Output('claude-3', $result, $messageBag);
+
+        $this->assertSame('claude-3', $output->getModel());
+        $this->assertSame($result, $output->getResult());
+        $this->assertSame($messageBag, $output->getMessageBag());
+        $this->assertSame([], $output->getOptions());
+    }
+
+    public function testGetModel()
+    {
+        $messageBag = new MessageBag();
+        $result = new TextResult('Test');
+
+        $output = new Output('test-model', $result, $messageBag);
+
+        $this->assertSame('test-model', $output->getModel());
+    }
+
+    public function testGetResult()
+    {
+        $messageBag = new MessageBag();
+        $result = new TextResult('Expected content');
+
+        $output = new Output('model', $result, $messageBag);
+
+        $retrievedResult = $output->getResult();
+
+        $this->assertSame($result, $retrievedResult);
+        $this->assertSame('Expected content', $retrievedResult->getContent());
+    }
+
+    public function testSetResult()
+    {
+        $messageBag = new MessageBag();
+        $originalResult = new TextResult('Original');
+        $output = new Output('model', $originalResult, $messageBag);
+
+        $newResult = new TextResult('New content');
+        $output->setResult($newResult);
+
+        $retrievedResult = $output->getResult();
+        $this->assertSame($newResult, $retrievedResult);
+        $this->assertSame('New content', $retrievedResult->getContent());
+    }
+
+    public function testGetMessageBag()
+    {
+        $messageBag = new MessageBag();
+        $messageBag->add(Message::ofUser('User message'));
+        $messageBag->add(Message::ofAssistant('Assistant reply'));
+
+        $result = new TextResult('Content');
+        $output = new Output('model', $result, $messageBag);
+
+        $retrievedMessageBag = $output->getMessageBag();
+
+        $this->assertSame($messageBag, $retrievedMessageBag);
+        $this->assertCount(2, $retrievedMessageBag);
+    }
+
+    public function testGetOptions()
+    {
+        $messageBag = new MessageBag();
+        $result = new TextResult('Content');
+        $options = ['max_tokens' => 500, 'temperature' => 0.8];
+
+        $output = new Output('model', $result, $messageBag, $options);
+
+        $this->assertSame($options, $output->getOptions());
+        $this->assertSame(500, $output->getOptions()['max_tokens']);
+        $this->assertSame(0.8, $output->getOptions()['temperature']);
+    }
+
+    public function testModelIsReadOnly()
+    {
+        $messageBag = new MessageBag();
+        $result = new TextResult('Content');
+
+        $output = new Output('original-model', $result, $messageBag);
+
+        $this->assertSame('original-model', $output->getModel());
+    }
+
+    public function testMessageBagIsReadOnly()
+    {
+        $messageBag = new MessageBag();
+        $messageBag->add(Message::ofUser('Test'));
+
+        $result = new TextResult('Content');
+        $output = new Output('model', $result, $messageBag);
+
+        $retrievedBag = $output->getMessageBag();
+        $this->assertSame($messageBag, $retrievedBag);
+    }
+
+    public function testOptionsIsReadOnly()
+    {
+        $messageBag = new MessageBag();
+        $result = new TextResult('Content');
+        $options = ['key' => 'value'];
+
+        $output = new Output('model', $result, $messageBag, $options);
+
+        $this->assertSame($options, $output->getOptions());
+    }
+}
diff --git a/src/chat/tests/Bridge/HttpFoundation/SessionStoreTest.php b/src/chat/tests/Bridge/HttpFoundation/SessionStoreTest.php
new file mode 100644
index 000000000..ddb6e625c
--- /dev/null
+++ b/src/chat/tests/Bridge/HttpFoundation/SessionStoreTest.php
@@ -0,0 +1,138 @@
+<?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\AI\Chat\Tests\Bridge\HttpFoundation;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\AI\Chat\Bridge\HttpFoundation\SessionStore;
+use Symfony\AI\Platform\Message\Message;
+use Symfony\AI\Platform\Message\MessageBag;
+use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Component\HttpFoundation\Session\SessionInterface;
+
+final class SessionStoreTest extends TestCase
+{
+    public function testSetupStoresEmptyMessageBag()
+    {
+        $session = $this->createMock(SessionInterface::class);
+        $requestStack = $this->createMock(RequestStack::class);
+
+        $requestStack->expects($this->once())
+            ->method('getSession')
+            ->willReturn($session);
+
+        $session->expects($this->once())
+            ->method('set')
+            ->with('messages', $this->isInstanceOf(MessageBag::class));
+
+        $store = new SessionStore($requestStack, 'messages');
+        $store->setup();
+    }
+
+    public function testSetupWithCustomSessionKey()
+    {
+        $session = $this->createMock(SessionInterface::class);
+        $requestStack = $this->createMock(RequestStack::class);
+
+        $requestStack->expects($this->once())
+            ->method('getSession')
+            ->willReturn($session);
+
+        $session->expects($this->once())
+            ->method('set')
+            ->with('custom_key', $this->isInstanceOf(MessageBag::class));
+
+        $store = new SessionStore($requestStack, 'custom_key');
+        $store->setup();
+    }
+
+    public function testSaveStoresMessageBag()
+    {
+        $messageBag = new MessageBag();
+        $messageBag->add(Message::ofUser('Test message'));
+
+        $session = $this->createMock(SessionInterface::class);
+        $requestStack = $this->createMock(RequestStack::class);
+
+        $requestStack->expects($this->once())
+            ->method('getSession')
+            ->willReturn($session);
+
+        $session->expects($this->once())
+            ->method('set')
+            ->with('messages', $messageBag);
+
+        $store = new SessionStore($requestStack, 'messages');
+        $store->save($messageBag);
+    }
+
+    public function testLoadReturnsStoredMessages()
+    {
+        $messageBag = new MessageBag();
+        $messageBag->add(Message::ofUser('Session message'));
+
+        $session = $this->createMock(SessionInterface::class);
+        $requestStack = $this->createMock(RequestStack::class);
+
+        $requestStack->expects($this->once())
+            ->method('getSession')
+            ->willReturn($session);
+
+        $session->expects($this->once())
+            ->method('get')
+            ->with('messages', $this->isInstanceOf(MessageBag::class))
+            ->willReturn($messageBag);
+
+        $store = new SessionStore($requestStack, 'messages');
+        $result = $store->load();
+
+        $this->assertSame($messageBag, $result);
+        $this->assertCount(1, $result);
+    }
+
+    public function testLoadReturnsEmptyMessageBagWhenNotSet()
+    {
+        $session = $this->createMock(SessionInterface::class);
+        $requestStack = $this->createMock(RequestStack::class);
+
+        $requestStack->expects($this->once())
+            ->method('getSession')
+            ->willReturn($session);
+
+        $session->expects($this->once())
+            ->method('get')
+            ->with('messages', $this->isInstanceOf(MessageBag::class))
+            ->willReturn(new MessageBag());
+
+        $store = new SessionStore($requestStack, 'messages');
+        $result = $store->load();
+
+        $this->assertInstanceOf(MessageBag::class, $result);
+        $this->assertCount(0, $result);
+    }
+
+    public function testDropRemovesSessionKey()
+    {
+        $session = $this->createMock(SessionInterface::class);
+        $requestStack = $this->createMock(RequestStack::class);
+
+        $requestStack->expects($this->once())
+            ->method('getSession')
+            ->willReturn($session);
+
+        $session->expects($this->once())
+            ->method('remove')
+            ->with('messages');
+
+        $store = new SessionStore($requestStack, 'messages');
+        $store->drop();
+    }
+}
diff --git a/src/chat/tests/Bridge/Local/CacheStoreTest.php b/src/chat/tests/Bridge/Local/CacheStoreTest.php
new file mode 100644
index 000000000..92d72e634
--- /dev/null
+++ b/src/chat/tests/Bridge/Local/CacheStoreTest.php
@@ -0,0 +1,164 @@
+<?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\AI\Chat\Tests\Bridge\Local;
+
+use PHPUnit\Framework\TestCase;
+use Psr\Cache\CacheItemInterface;
+use Psr\Cache\CacheItemPoolInterface;
+use Symfony\AI\Chat\Bridge\Local\CacheStore;
+use Symfony\AI\Platform\Message\Message;
+use Symfony\AI\Platform\Message\MessageBag;
+
+final class CacheStoreTest extends TestCase
+{
+    public function testSetupStoresEmptyMessageBag()
+    {
+        $cache = $this->createMock(CacheItemPoolInterface::class);
+        $cacheItem = $this->createMock(CacheItemInterface::class);
+
+        $cache->expects($this->once())
+            ->method('getItem')
+            ->with('test_key')
+            ->willReturn($cacheItem);
+
+        $cacheItem->expects($this->once())
+            ->method('set')
+            ->with($this->isInstanceOf(MessageBag::class));
+
+        $cacheItem->expects($this->once())
+            ->method('expiresAfter')
+            ->with(86400)
+            ->willReturn($cacheItem);
+
+        $cache->expects($this->once())
+            ->method('save')
+            ->with($cacheItem);
+
+        $store = new CacheStore($cache, 'test_key');
+        $store->setup();
+    }
+
+    public function testSetupWithCustomTtl()
+    {
+        $cache = $this->createMock(CacheItemPoolInterface::class);
+        $cacheItem = $this->createMock(CacheItemInterface::class);
+
+        $cache->method('getItem')->willReturn($cacheItem);
+        $cacheItem->method('set')->willReturn($cacheItem);
+
+        $cacheItem->expects($this->once())
+            ->method('expiresAfter')
+            ->with(3600)
+            ->willReturn($cacheItem);
+
+        $cache->expects($this->once())
+            ->method('save')
+            ->with($cacheItem);
+
+        $store = new CacheStore($cache, 'test_key', 3600);
+        $store->setup();
+    }
+
+    public function testSaveStoresMessageBag()
+    {
+        $messageBag = new MessageBag();
+        $messageBag->add(Message::ofUser('Test message'));
+
+        $cache = $this->createMock(CacheItemPoolInterface::class);
+        $cacheItem = $this->createMock(CacheItemInterface::class);
+
+        $cache->expects($this->once())
+            ->method('getItem')
+            ->with('messages')
+            ->willReturn($cacheItem);
+
+        $cacheItem->expects($this->once())
+            ->method('set')
+            ->with($messageBag);
+
+        $cacheItem->expects($this->once())
+            ->method('expiresAfter')
+            ->with(86400)
+            ->willReturn($cacheItem);
+
+        $cache->expects($this->once())
+            ->method('save')
+            ->with($cacheItem);
+
+        $store = new CacheStore($cache, 'messages');
+        $store->save($messageBag);
+    }
+
+    public function testLoadReturnsStoredMessages()
+    {
+        $messageBag = new MessageBag();
+        $messageBag->add(Message::ofUser('Cached message'));
+
+        $cache = $this->createMock(CacheItemPoolInterface::class);
+        $cacheItem = $this->createMock(CacheItemInterface::class);
+
+        $cache->expects($this->once())
+            ->method('getItem')
+            ->with('test_key')
+            ->willReturn($cacheItem);
+
+        $cacheItem->expects($this->once())
+            ->method('isHit')
+            ->willReturn(true);
+
+        $cacheItem->expects($this->once())
+            ->method('get')
+            ->willReturn($messageBag);
+
+        $store = new CacheStore($cache, 'test_key');
+        $result = $store->load();
+
+        $this->assertSame($messageBag, $result);
+        $this->assertCount(1, $result);
+    }
+
+    public function testLoadReturnsEmptyMessageBagWhenCacheMiss()
+    {
+        $cache = $this->createMock(CacheItemPoolInterface::class);
+        $cacheItem = $this->createMock(CacheItemInterface::class);
+
+        $cache->expects($this->once())
+            ->method('getItem')
+            ->with('test_key')
+            ->willReturn($cacheItem);
+
+        $cacheItem->expects($this->once())
+            ->method('isHit')
+            ->willReturn(false);
+
+        $cacheItem->expects($this->never())
+            ->method('get');
+
+        $store = new CacheStore($cache, 'test_key');
+        $result = $store->load();
+
+        $this->assertInstanceOf(MessageBag::class, $result);
+        $this->assertCount(0, $result);
+    }
+
+    public function testDropDeletesCacheItem()
+    {
+        $cache = $this->createMock(CacheItemPoolInterface::class);
+
+        $cache->expects($this->once())
+            ->method('deleteItem')
+            ->with('messages');
+
+        $store = new CacheStore($cache, 'messages');
+        $store->drop();
+    }
+}
diff --git a/src/chat/tests/Bridge/Local/InMemoryStoreTest.php b/src/chat/tests/Bridge/Local/InMemoryStoreTest.php
new file mode 100644
index 000000000..dc19e02c3
--- /dev/null
+++ b/src/chat/tests/Bridge/Local/InMemoryStoreTest.php
@@ -0,0 +1,105 @@
+<?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\AI\Chat\Tests\Bridge\Local;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\AI\Chat\Bridge\Local\InMemoryStore;
+use Symfony\AI\Platform\Message\Content\Text;
+use Symfony\AI\Platform\Message\Message;
+use Symfony\AI\Platform\Message\MessageBag;
+use Symfony\AI\Platform\Message\UserMessage;
+
+final class InMemoryStoreTest extends TestCase
+{
+    public function testSetupInitializesEmptyMessageBag()
+    {
+        $store = new InMemoryStore();
+        $store->setup();
+
+        $messages = $store->load();
+
+        $this->assertInstanceOf(MessageBag::class, $messages);
+        $this->assertCount(0, $messages);
+    }
+
+    public function testSaveStoresMessageBag()
+    {
+        $store = new InMemoryStore();
+
+        $messageBag = new MessageBag();
+        $messageBag->add(Message::ofUser('Hello'));
+        $messageBag->add(Message::ofAssistant('Hi there'));
+
+        $store->save($messageBag);
+
+        $loadedMessages = $store->load();
+
+        $this->assertSame($messageBag, $loadedMessages);
+        $this->assertCount(2, $loadedMessages);
+    }
+
+    public function testLoadReturnsEmptyMessageBagWhenNotInitialized()
+    {
+        $store = new InMemoryStore();
+
+        $messages = $store->load();
+
+        $this->assertInstanceOf(MessageBag::class, $messages);
+        $this->assertCount(0, $messages);
+    }
+
+    public function testLoadReturnsStoredMessages()
+    {
+        $store = new InMemoryStore();
+        $store->setup();
+
+        $messageBag = new MessageBag();
+        $messageBag->add(Message::ofUser('Test message'));
+
+        $store->save($messageBag);
+
+        $loadedMessages = $store->load();
+
+        $this->assertCount(1, $loadedMessages);
+        $messages = $loadedMessages->getMessages();
+        $this->assertInstanceOf(UserMessage::class, $messages[0]);
+        $this->assertInstanceOf(Text::class, $messages[0]->content[0]);
+        $this->assertSame('Test message', $messages[0]->content[0]->text);
+    }
+
+    public function testDropClearsMessages()
+    {
+        $store = new InMemoryStore();
+
+        $messageBag = new MessageBag();
+        $messageBag->add(Message::ofUser('Message 1'));
+        $messageBag->add(Message::ofUser('Message 2'));
+
+        $store->save($messageBag);
+        $this->assertCount(2, $store->load());
+
+        $store->drop();
+
+        $messages = $store->load();
+        $this->assertCount(0, $messages);
+    }
+
+    public function testSetupOptions()
+    {
+        $store = new InMemoryStore();
+
+        $store->setup(['foo' => 'bar']);
+
+        $messages = $store->load();
+        $this->assertInstanceOf(MessageBag::class, $messages);
+    }
+}