feature #871 [Platform] Migrate OpenAI to Responses API (paulinevos)

This PR was squashed before being merged into the main branch.

Discussion
----------

[Platform] Migrate OpenAI to Responses API

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Docs?         | yes
| Issues        | Fix #796
| License       | MIT

This PR migrates OpenAI from chat completions (deprecated) to the Responses API. I tried to keep the scope small and just support everything already in place as seamlessly as possible. The Responses API does offer some more functionality that we should look into supporting (e.g. MCP tool calling, expanded reasoning functionality), but I found that OOS for this migration.

One thing to note it that the Responses API as of now lacks Audio capabilities ("coming soon", according to the docs), so that example is temporarily disabled and so is the `Gpt` audio capability for now.

**Note: my PRs are best reviewed commit by commit**

Commits
-------

82ec95b [Platform] Migrate OpenAI to Responses API

Author: chr-hertel

examples/openai/audio-input.php

@@ -9,21 +9,19 @@
  * file that was distributed with this source code.
  */
 
-use Symfony\AI\Platform\Bridge\OpenAi\PlatformFactory;
-use Symfony\AI\Platform\Message\Content\Audio;
-use Symfony\AI\Platform\Message\Message;
-use Symfony\AI\Platform\Message\MessageBag;
+use Symfony\AI\Platform\Exception\RuntimeException;
 
 require_once dirname(__DIR__).'/bootstrap.php';
 
-$platform = PlatformFactory::create(env('OPENAI_API_KEY'), http_client());
-
-$messages = new MessageBag(
-    Message::ofUser(
-        'What is this recording about?',
-        Audio::fromFile(dirname(__DIR__, 2).'/fixtures/audio.mp3'),
-    ),
-);
-$result = $platform->invoke('gpt-4o-audio-preview', $messages);
-
-echo $result->asText().\PHP_EOL;
+throw new RuntimeException('This example is temporarily unavailable due to migration to Responses API (which does not support audio yet).');
+// $platform = PlatformFactory::create(env('OPENAI_API_KEY'), http_client());
+//
+// $messages = new MessageBag(
+//    Message::ofUser(
+//        'What is this recording about?',
+//        Audio::fromFile(dirname(__DIR__, 2).'/fixtures/audio.mp3'),
+//    ),
+// );
+// $result = $platform->invoke('gpt-4o-audio-preview', $messages);
+//
+// echo $result->asText().\PHP_EOL;

examples/openai/chat-with-string-options.php

@@ -21,6 +21,6 @@
     Message::forSystem('You are a pirate and you write funny.'),
     Message::ofUser('What is the Symfony framework?'),
 );
-$result = $platform->invoke('gpt-4o-mini?max_tokens=7', $messages);
+$result = $platform->invoke('gpt-4o-mini?max_output_tokens=16', $messages);
 
 echo $result->asText().\PHP_EOL;

examples/openai/chat.php

@@ -22,7 +22,7 @@
     Message::ofUser('What is the Symfony framework?'),
 );
 $result = $platform->invoke('gpt-4o-mini', $messages, [
-    'max_tokens' => 500, // specific options just for this call
+    'max_output_tokens' => 500, // specific options just for this call
 ]);
 
 echo $result->asText().\PHP_EOL;

examples/openai/token-metadata.php

@@ -25,7 +25,7 @@
     Message::ofUser('What is the Symfony framework?'),
 );
 $result = $agent->call($messages, [
-    'max_tokens' => 500, // specific options just for this call
+    'max_output_tokens' => 500, // specific options just for this call
 ]);
 
 print_token_usage($result->getMetadata());

src/platform/src/Bridge/OpenAi/Contract/Gpt/Message/AssistantMessageNormalizer.php

@@ -0,0 +1,59 @@
+<?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\Platform\Bridge\OpenAi\Contract\Gpt\Message;
+
+use Symfony\AI\Platform\Bridge\OpenAi\Gpt;
+use Symfony\AI\Platform\Contract\Normalizer\ModelContractNormalizer;
+use Symfony\AI\Platform\Message\AssistantMessage;
+use Symfony\AI\Platform\Model;
+use Symfony\Component\Serializer\Normalizer\NormalizerAwareInterface;
+use Symfony\Component\Serializer\Normalizer\NormalizerAwareTrait;
+
+/**
+ * @author Guillermo Lengemann <guillermo.lengemann@gmail.com>
+ */
+final class AssistantMessageNormalizer extends ModelContractNormalizer implements NormalizerAwareInterface
+{
+    use NormalizerAwareTrait;
+
+    /**
+     * @param AssistantMessage $data
+     *
+     * @return array{
+     *     role: 'assistant',
+     *     type: 'message',
+     *     content: ?string
+     * }
+     */
+    public function normalize(mixed $data, ?string $format = null, array $context = []): array
+    {
+        if ($data->hasToolCalls()) {
+            return $this->normalizer->normalize($data->getToolCalls(), $format, $context);
+        }
+
+        return [
+            'role' => $data->getRole()->value,
+            'type' => 'message',
+            'content' => $data->getContent(),
+        ];
+    }
+
+    protected function supportedDataClass(): string
+    {
+        return AssistantMessage::class;
+    }
+
+    protected function supportsModel(Model $model): bool
+    {
+        return $model instanceof Gpt;
+    }
+}

src/platform/src/Bridge/OpenAi/Contract/Gpt/Message/Content/DocumentNormalizer.php

@@ -0,0 +1,49 @@
+<?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\Platform\Bridge\OpenAi\Contract\Gpt\Message\Content;
+
+use Symfony\AI\Platform\Bridge\OpenAi\Gpt;
+use Symfony\AI\Platform\Capability;
+use Symfony\AI\Platform\Contract\Normalizer\ModelContractNormalizer;
+use Symfony\AI\Platform\Message\Content\Document;
+use Symfony\AI\Platform\Message\Content\File;
+use Symfony\AI\Platform\Model;
+
+/**
+ * @author Guillermo Lengemann <guillermo.lengemann@gmail.com>
+ */
+class DocumentNormalizer extends ModelContractNormalizer
+{
+    /**
+     * @param File $data
+     *
+     * @return array{type: 'input_file', filename: string, file_data: string}
+     */
+    public function normalize(mixed $data, ?string $format = null, array $context = []): array
+    {
+        return [
+            'type' => 'input_file',
+            'filename' => $data->getFilename(),
+            'file_data' => $data->asDataUrl(),
+        ];
+    }
+
+    protected function supportedDataClass(): string
+    {
+        return Document::class;
+    }
+
+    protected function supportsModel(Model $model): bool
+    {
+        return $model instanceof Gpt && $model->supports(Capability::INPUT_PDF);
+    }
+}

src/platform/src/Bridge/OpenAi/Contract/Gpt/Message/Content/ImageNormalizer.php

@@ -0,0 +1,50 @@
+<?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\Platform\Bridge\OpenAi\Contract\Gpt\Message\Content;
+
+use Symfony\AI\Platform\Bridge\OpenAi\Gpt;
+use Symfony\AI\Platform\Capability;
+use Symfony\AI\Platform\Contract\Normalizer\ModelContractNormalizer;
+use Symfony\AI\Platform\Message\Content\Image;
+use Symfony\AI\Platform\Model;
+
+/**
+ * See: https://platform.openai.com/docs/guides/images-vision#giving-a-model-images-as-input.
+ */
+final class ImageNormalizer extends ModelContractNormalizer
+{
+    /**
+     * @param Image $data
+     *
+     * @return array{
+     *      type: 'input_image',
+     *      image_url: string
+     *  }
+     */
+    public function normalize(mixed $data, ?string $format = null, array $context = []): array
+    {
+        return [
+            'type' => 'input_image',
+            'image_url' => $data->asDataUrl(),
+        ];
+    }
+
+    protected function supportedDataClass(): string
+    {
+        return Image::class;
+    }
+
+    protected function supportsModel(Model $model): bool
+    {
+        return $model instanceof Gpt && $model->supports(Capability::INPUT_IMAGE);
+    }
+}

src/platform/src/Bridge/OpenAi/Contract/Gpt/Message/Content/ImageUrlNormalizer.php

@@ -0,0 +1,50 @@
+<?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\Platform\Bridge\OpenAi\Contract\Gpt\Message\Content;
+
+use Symfony\AI\Platform\Bridge\OpenAi\Gpt;
+use Symfony\AI\Platform\Capability;
+use Symfony\AI\Platform\Contract\Normalizer\ModelContractNormalizer;
+use Symfony\AI\Platform\Message\Content\ImageUrl;
+use Symfony\AI\Platform\Model;
+
+/**
+ * See: https://platform.openai.com/docs/guides/images-vision#giving-a-model-images-as-input.
+ */
+final class ImageUrlNormalizer extends ModelContractNormalizer
+{
+    /**
+     * @param ImageUrl $data
+     *
+     * @return array{
+     *      type: 'input_image',
+     *      image_url: string
+     *  }
+     */
+    public function normalize(mixed $data, ?string $format = null, array $context = []): array
+    {
+        return [
+            'type' => 'input_image',
+            'image_url' => $data->getUrl(),
+        ];
+    }
+
+    protected function supportedDataClass(): string
+    {
+        return ImageUrl::class;
+    }
+
+    protected function supportsModel(Model $model): bool
+    {
+        return $model instanceof Gpt && $model->supports(Capability::INPUT_IMAGE);
+    }
+}

src/platform/src/Bridge/OpenAi/Contract/Gpt/Message/Content/TextNormalizer.php

@@ -0,0 +1,49 @@
+<?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\Platform\Bridge\OpenAi\Contract\Gpt\Message\Content;
+
+use Symfony\AI\Platform\Bridge\OpenAi\Gpt;
+use Symfony\AI\Platform\Contract\Normalizer\ModelContractNormalizer;
+use Symfony\AI\Platform\Message\Content\Text;
+use Symfony\AI\Platform\Model;
+
+/**
+ * See: https://platform.openai.com/docs/guides/images-vision#giving-a-model-images-as-input.
+ */
+final class TextNormalizer extends ModelContractNormalizer
+{
+    /**
+     * @param Text $data
+     *
+     * @return array{
+     *     type: 'input_text',
+     *     text: string
+     * }
+     */
+    public function normalize(mixed $data, ?string $format = null, array $context = []): array
+    {
+        return [
+            'type' => 'input_text',
+            'text' => $data->getText(),
+        ];
+    }
+
+    protected function supportedDataClass(): string
+    {
+        return Text::class;
+    }
+
+    protected function supportsModel(Model $model): bool
+    {
+        return $model instanceof Gpt;
+    }
+}

src/platform/src/Bridge/OpenAi/Contract/Gpt/Message/MessageBagNormalizer.php

@@ -0,0 +1,72 @@
+<?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\Platform\Bridge\OpenAi\Contract\Gpt\Message;
+
+use Symfony\AI\Platform\Bridge\OpenAi\Gpt;
+use Symfony\AI\Platform\Contract\Normalizer\ModelContractNormalizer;
+use Symfony\AI\Platform\Message\AssistantMessage;
+use Symfony\AI\Platform\Message\MessageBag;
+use Symfony\AI\Platform\Model;
+use Symfony\Component\Serializer\Exception\ExceptionInterface;
+use Symfony\Component\Serializer\Normalizer\NormalizerAwareInterface;
+use Symfony\Component\Serializer\Normalizer\NormalizerAwareTrait;
+
+/**
+ * @author Pauline Vos <pauline.vos@mongodb.com>
+ */
+final class MessageBagNormalizer extends ModelContractNormalizer implements NormalizerAwareInterface
+{
+    use NormalizerAwareTrait;
+
+    /**
+     * @param MessageBag $data
+     *
+     * @return array{
+     *     input: array<string, mixed>,
+     *     model?: string,
+     *     system?: string,
+     * }
+     *
+     * @throws ExceptionInterface
+     */
+    public function normalize(mixed $data, ?string $format = null, array $context = []): array
+    {
+        $messages['input'] = [];
+
+        foreach ($data->withoutSystemMessage()->getMessages() as $message) {
+            $normalized = $this->normalizer->normalize($message, $format, $context);
+
+            if ($message instanceof AssistantMessage && $message->hasToolCalls()) {
+                $messages['input'] = array_merge($messages['input'], $normalized);
+                continue;
+            }
+
+            $messages['input'][] = $normalized;
+        }
+
+        if ($data->getSystemMessage()) {
+            $messages['instructions'] = $data->getSystemMessage()->getContent();
+        }
+
+        return $messages;
+    }
+
+    protected function supportedDataClass(): string
+    {
+        return MessageBag::class;
+    }
+
+    protected function supportsModel(Model $model): bool
+    {
+        return $model instanceof Gpt;
+    }
+}