[Agent] Introduce "session" - POC

examples/misc/persistent-chat-double-agent.php

@@ -0,0 +1,45 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+use Symfony\AI\Agent\Agent;
+use Symfony\AI\Agent\Chat;
+use Symfony\AI\Agent\Chat\MessageStore\InMemoryStore;
+use Symfony\AI\Platform\Bridge\OpenAi\Gpt;
+use Symfony\AI\Platform\Bridge\OpenAi\PlatformFactory;
+use Symfony\AI\Platform\Message\Message;
+use Symfony\AI\Platform\Message\MessageBag;
+
+require_once dirname(__DIR__).'/bootstrap.php';
+
+$platform = PlatformFactory::create(env('OPENAI_API_KEY'), http_client());
+$llm = new Gpt(Gpt::GPT_4O_MINI);
+
+$firstAgent = new Agent($platform, $llm, logger: logger());
+$secondAgent = new Agent($platform, $llm, logger: logger());
+
+$store = new InMemoryStore();
+
+$firstChat = new Chat($firstAgent, $store);
+$secondChat = new Chat($secondAgent, $store);
+
+$firstChat->initiate(new MessageBag(
+    Message::forSystem('You are a helpful assistant. You only answer with short sentences.'),
+));
+$secondChat->initiate(new MessageBag(
+    Message::forSystem('You are a helpful assistant. You only answer with short sentences.'),
+));
+
+$firstChat->submit(Message::ofUser('My name is Christopher.'));
+$firstChatMessage = $firstChat->submit(Message::ofUser('What is my name?'));
+$secondChatMessage = $secondChat->submit(Message::ofUser('What is my name?'));
+
+echo $firstChatMessage->content.\PHP_EOL;
+echo $secondChatMessage->content.\PHP_EOL;

src/agent/src/Agent.php

@@ -21,6 +21,9 @@
 use Symfony\AI\Platform\Model;
 use Symfony\AI\Platform\PlatformInterface;
 use Symfony\AI\Platform\Result\ResultInterface;
+use Symfony\Component\Uid\AbstractUid;
+use Symfony\Component\Uid\TimeBasedUidInterface;
+use Symfony\Component\Uid\Uuid;
 use Symfony\Contracts\HttpClient\Exception\ClientExceptionInterface;
 use Symfony\Contracts\HttpClient\Exception\HttpExceptionInterface;
 
@@ -29,6 +32,8 @@
  */
 final readonly class Agent implements AgentInterface
 {
+    private AbstractUid&TimeBasedUidInterface $id;
+
     /**
      * @var InputProcessorInterface[]
      */
@@ -52,6 +57,8 @@ public function __construct(
     ) {
         $this->inputProcessors = $this->initializeProcessors($inputProcessors, InputProcessorInterface::class);
         $this->outputProcessors = $this->initializeProcessors($outputProcessors, OutputProcessorInterface::class);
+
+        $this->id = Uuid::v7();
     }
 
     /**
@@ -97,6 +104,11 @@ public function call(MessageBagInterface $messages, array $options = []): Result
         return $output->result;
     }
 
+    public function getId(): AbstractUid&TimeBasedUidInterface
+    {
+        return $this->id;
+    }
+
     /**
      * @param InputProcessorInterface[]|OutputProcessorInterface[] $processors
      * @param class-string                                         $interface

src/agent/src/AgentInterface.php

@@ -14,6 +14,8 @@
 use Symfony\AI\Agent\Exception\ExceptionInterface;
 use Symfony\AI\Platform\Message\MessageBagInterface;
 use Symfony\AI\Platform\Result\ResultInterface;
+use Symfony\Component\Uid\AbstractUid;
+use Symfony\Component\Uid\TimeBasedUidInterface;
 
 /**
  * @author Denis Zunke <[email protected]>
@@ -26,4 +28,6 @@ interface AgentInterface
      * @throws ExceptionInterface When the agent encounters an error (e.g., unsupported model capabilities, invalid arguments, network failures, or processor errors)
      */
     public function call(MessageBagInterface $messages, array $options = []): ResultInterface;
+
+    public function getId(): AbstractUid&TimeBasedUidInterface;
 }

src/agent/src/Chat.php

@@ -18,6 +18,9 @@
 use Symfony\AI\Platform\Message\UserMessage;
 use Symfony\AI\Platform\Result\TextResult;
 
+/**
+ * @author Christopher Hertel <[email protected]>
+ */
 final readonly class Chat implements ChatInterface
 {
     public function __construct(
@@ -28,23 +31,25 @@ public function __construct(
 
     public function initiate(MessageBagInterface $messages): void
     {
-        $this->store->clear();
+        $messages->setSession($this->agent->getId());
+
+        $this->store->clear($messages->getSession());
         $this->store->save($messages);
     }
 
     public function submit(UserMessage $message): AssistantMessage
     {
-        $messages = $this->store->load();
+        $messagesBag = $this->store->load($this->agent->getId());
 
-        $messages->add($message);
-        $result = $this->agent->call($messages);
+        $messagesBag->add($message);
+        $result = $this->agent->call($messagesBag);
 
         \assert($result instanceof TextResult);
 
         $assistantMessage = Message::ofAssistant($result->getContent());
-        $messages->add($assistantMessage);
+        $messagesBag->add($assistantMessage);
 
-        $this->store->save($messages);
+        $this->store->save($messagesBag);
 
         return $assistantMessage;
     }

src/agent/src/Chat/MessageStore/CacheStore.php

@@ -16,12 +16,13 @@
 use Symfony\AI\Agent\Exception\RuntimeException;
 use Symfony\AI\Platform\Message\MessageBag;
 use Symfony\AI\Platform\Message\MessageBagInterface;
+use Symfony\Component\Uid\AbstractUid;
+use Symfony\Component\Uid\TimeBasedUidInterface;
 
 final readonly class CacheStore implements MessageStoreInterface
 {
     public function __construct(
         private CacheItemPoolInterface $cache,
-        private string $cacheKey,
         private int $ttl = 86400,
     ) {
         if (!interface_exists(CacheItemPoolInterface::class)) {
@@ -31,23 +32,23 @@ public function __construct(
 
     public function save(MessageBagInterface $messages): void
     {
-        $item = $this->cache->getItem($this->cacheKey);
+        $item = $this->cache->getItem($messages->getSession()->toRfc4122());
 
         $item->set($messages);
         $item->expiresAfter($this->ttl);
 
         $this->cache->save($item);
     }
 
-    public function load(): MessageBag
+    public function load(AbstractUid&TimeBasedUidInterface $session): MessageBagInterface
     {
-        $item = $this->cache->getItem($this->cacheKey);
+        $item = $this->cache->getItem($session->toRfc4122());
 
         return $item->isHit() ? $item->get() : new MessageBag();
     }
 
-    public function clear(): void
+    public function clear(AbstractUid&TimeBasedUidInterface $session): void
     {
-        $this->cache->deleteItem($this->cacheKey);
+        $this->cache->deleteItem($session->toRfc4122());
     }
 }

src/agent/src/Chat/MessageStore/InMemoryStore.php

@@ -14,23 +14,28 @@
 use Symfony\AI\Agent\Chat\MessageStoreInterface;
 use Symfony\AI\Platform\Message\MessageBag;
 use Symfony\AI\Platform\Message\MessageBagInterface;
+use Symfony\Component\Uid\AbstractUid;
+use Symfony\Component\Uid\TimeBasedUidInterface;
 
 final class InMemoryStore implements MessageStoreInterface
 {
-    private MessageBagInterface $messages;
+    /**
+     * @var MessageBagInterface[]
+     */
+    private array $messageBags;
 
     public function save(MessageBagInterface $messages): void
     {
-        $this->messages = $messages;
+        $this->messageBags[$messages->getSession()->toRfc4122()] = $messages;
     }
 
-    public function load(): MessageBagInterface
+    public function load(AbstractUid&TimeBasedUidInterface $session): MessageBagInterface
     {
-        return $this->messages ?? new MessageBag();
+        return $this->messageBags[$session->toRfc4122()] ?? new MessageBag();
     }
 
-    public function clear(): void
+    public function clear(AbstractUid&TimeBasedUidInterface $session): void
     {
-        $this->messages = new MessageBag();
+        $this->messageBags[$session->toRfc4122()] = new MessageBag();
     }
 }

src/agent/src/Chat/MessageStore/SessionStore.php

@@ -17,14 +17,15 @@
 use Symfony\AI\Platform\Message\MessageBagInterface;
 use Symfony\Component\HttpFoundation\RequestStack;
 use Symfony\Component\HttpFoundation\Session\SessionInterface;
+use Symfony\Component\Uid\AbstractUid;
+use Symfony\Component\Uid\TimeBasedUidInterface;
 
 final readonly class SessionStore implements MessageStoreInterface
 {
     private SessionInterface $session;
 
     public function __construct(
         RequestStack $requestStack,
-        private string $sessionKey = 'messages',
     ) {
         if (!class_exists(RequestStack::class)) {
             throw new RuntimeException('For using the SessionStore as message store, the symfony/http-foundation package is required. Try running "composer require symfony/http-foundation".');
@@ -34,16 +35,16 @@ public function __construct(
 
     public function save(MessageBagInterface $messages): void
     {
-        $this->session->set($this->sessionKey, $messages);
+        $this->session->set($messages->getSession()->toRfc4122(), $messages);
     }
 
-    public function load(): MessageBagInterface
+    public function load(AbstractUid&TimeBasedUidInterface $session): MessageBagInterface
     {
-        return $this->session->get($this->sessionKey, new MessageBag());
+        return $this->session->get($session->toRfc4122(), new MessageBag());
     }
 
-    public function clear(): void
+    public function clear(AbstractUid&TimeBasedUidInterface $session): void
     {
-        $this->session->remove($this->sessionKey);
+        $this->session->remove($session->toRfc4122());
     }
 }

src/agent/src/Chat/MessageStoreInterface.php

@@ -12,12 +12,14 @@
 namespace Symfony\AI\Agent\Chat;
 
 use Symfony\AI\Platform\Message\MessageBagInterface;
+use Symfony\Component\Uid\AbstractUid;
+use Symfony\Component\Uid\TimeBasedUidInterface;
 
 interface MessageStoreInterface
 {
     public function save(MessageBagInterface $messages): void;
 
-    public function load(): MessageBagInterface;
+    public function load(AbstractUid&TimeBasedUidInterface $session): MessageBagInterface;
 
-    public function clear(): void;
+    public function clear(AbstractUid&TimeBasedUidInterface $session): void;
 }

src/agent/tests/AgentTest.php

@@ -19,6 +19,8 @@
 use Symfony\AI\Agent\Agent;
 use Symfony\AI\Agent\AgentAwareInterface;
 use Symfony\AI\Agent\AgentInterface;
+use Symfony\AI\Agent\Chat;
+use Symfony\AI\Agent\Chat\MessageStore\InMemoryStore;
 use Symfony\AI\Agent\Exception\InvalidArgumentException;
 use Symfony\AI\Agent\Exception\MissingModelSupportException;
 use Symfony\AI\Agent\Exception\RuntimeException;
@@ -30,6 +32,7 @@
 use Symfony\AI\Platform\Message\Content\Audio;
 use Symfony\AI\Platform\Message\Content\Image;
 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;
 use Symfony\AI\Platform\Model;
@@ -49,6 +52,8 @@
 #[UsesClass(Text::class)]
 #[UsesClass(Audio::class)]
 #[UsesClass(Image::class)]
+#[UsesClass(InMemoryStore::class)]
+#[UsesClass(Chat::class)]
 #[Small]
 final class AgentTest extends TestCase
 {
@@ -395,4 +400,32 @@ public function testConstructorAcceptsTraversableProcessors()
 
         $this->assertInstanceOf(AgentInterface::class, $agent);
     }
+
+    public function testDoubleAgentCanUseSameMessageStore()
+    {
+        $platform = $this->createMock(PlatformInterface::class);
+        $model = $this->createMock(Model::class);
+
+        $firstAgent = new Agent($platform, $model);
+        $secondAgent = new Agent($platform, $model);
+
+        $store = new InMemoryStore();
+
+        $firstChat = new Chat($firstAgent, $store);
+        $secondChat = new Chat($secondAgent, $store);
+
+        $messages = new MessageBag(
+            Message::forSystem('You are a helpful assistant. You only answer with short sentences.'),
+        );
+
+        $firstChat->initiate($messages);
+        $firstChat->submit(new UserMessage(new Text('Hello')));
+
+        $secondChat->initiate($messages);
+        $secondChat->submit(new UserMessage(new Text('Hello')));
+        $secondChat->submit(new UserMessage(new Text('Hello there')));
+
+        $this->assertCount(1, $store->load($firstAgent->getId()));
+        $this->assertCount(2, $store->load($secondAgent->getId()));
+    }
 }

src/platform/src/Message/MessageBag.php

@@ -11,6 +11,10 @@
 
 namespace Symfony\AI\Platform\Message;
 
+use Symfony\AI\Platform\Exception\RuntimeException;
+use Symfony\Component\Uid\AbstractUid;
+use Symfony\Component\Uid\TimeBasedUidInterface;
+
 /**
  * @final
  *
@@ -23,6 +27,8 @@ class MessageBag implements MessageBagInterface
      */
     private array $messages;
 
+    private (AbstractUid&TimeBasedUidInterface)|null $session = null;
+
     public function __construct(MessageInterface ...$messages)
     {
         $this->messages = array_values($messages);
@@ -109,6 +115,20 @@ public function containsImage(): bool
         return false;
     }
 
+    public function setSession(AbstractUid&TimeBasedUidInterface $session): void
+    {
+        $this->session = $session;
+    }
+
+    public function getSession(): AbstractUid&TimeBasedUidInterface
+    {
+        if (!$this->session instanceof TimeBasedUidInterface) {
+            throw new RuntimeException('Current message bag session is not set.');
+        }
+
+        return $this->session;
+    }
+
     public function count(): int
     {
         return \count($this->messages);