[Platform][RFC] OpenAI Responses API

[glengemann]

Q	A
Bug fix?	no
New feature?	yes
Docs?	no
Issues	Fix #...
License	MIT

Hi! I've been playing around with the new OpenAI Responses API for a project. Just wondering if the changes in this branch are moving in the right direction.

[chr-hertel]

Hey @glengemann, thanks for working on this and thanks for checking in early for feedback 👍

I notice some things here:

• in general I'd like to avoid different endpoint or models having impact to the Agent component - it might not always be possible and you found an unflexible part of the code there. I would rather try to bring in some extension points or contract handling - like with the tool schema - instead of just duplicating the AgentProcessor and ResponseFormatFactory
• also with the changes within the Platform component there is a lot of duplication going on, e.g. 'GPTandResponsesclasses are basically the same - we just need it here because we can't differentiate the other extension points, like theInputBagNormalizer` in a different way - that's unfortunate.

what I'm basically saying here, I get why you checked in early - somehow this duplication feels odd, but the current extension points, like those supports methods, don't provide more flexibility.

In those cases I'd like to start from the user land code: how would we want the user to select the different apis? do they care at this point?

let's image we would use this:

use Symfony\AI\Platform\Bridge\OpenAI;

$platform = OpenAI\PlatformFactory($apiKey);
$model = new OpenAI\GPT();

$response = $platform->request($model, $messages);

vs.

use Symfony\AI\Platform\Bridge\OpenAI;

$platform = OpenAI\PlatformFactory($apiKey);
$model = new OpenAI\Responses();

$response = $platform->request($model, $messages);

So, my questions:

• What would be the difference from a user point of view? Which features do we gain by adopting the Responses API?
• If there is a benefit, could we go with something like this?

  use Symfony\AI\Platform\Bridge\OpenAI;
  
  $platform = OpenAI\PlatformFactory($apiKey);
  $model = new OpenAI\GPT();
  
  $response = $platform->request($model, $messages, ['api' => 'responses']); // with default ['api => 'completions']

If we'd go with an option, we would need to find a way to extend the supports methods to check for that - and the OpenAI\ModelClient would need to interpret that to choose the right endpoint.