composer require openai-php/laravel
php artisan vendor:publish --provider="OpenAI\Laravel\ServiceProvider"

OPENAI_API_KEY=sk-proj-...

namespace App\Services;
use OpenAI\Laravel\Facades\OpenAI;

...

public function send(Request $request): JsonResponse
{
    $messages = $request->input('history', []);
...

return response()->stream(function () use ($messages) {
    foreach ($this->openAI->stream($messages) as $chunk) {
        echo "data: " . json_encode(['chunk' => $chunk]) . "\n\n";
...

use OpenAI\Exceptions\ErrorException;
use OpenAI\Exceptions\TransporterException;

...

OpenAI::fake([CreateResponse::fake(['choices' => [['message' => ['content' => 'Hi!']]]])]);
$reply = app(OpenAIService::class)->chat([['role' => 'user', 'content' => 'Hello']]);
$this->assertEquals('Hi!', $reply);