Streaming inference openai responses

<?php
require 'examples/boot.php';

use Cognesy\Messages\Messages;
use Cognesy\Polyglot\Inference\Inference;
use Cognesy\Utils\Str;

$expectedPhrase = 'paris';
$prompt = 'Describe the history of Paris in exactly 3 sentences.';

$stream = Inference::using('openai-responses')
    ->withMessages(Messages::fromString($prompt))
    ->withOptions(['max_output_tokens' => 256])
    ->withStreaming()
    ->stream()
    ->onDelta(fn($delta) => print($delta->contentDelta));

$assembled = '';
$deltaCount = 0;

foreach ($stream->deltas() as $delta) {
    $contentDelta = $delta->contentDelta;
    if ($contentDelta === '') {
        continue;
    }
    $deltaCount += 1;
    $assembled .= $contentDelta;
}

$final = $stream->final();
assert($final !== null, 'Expected a final response');
$finalContent = $final->content();

echo "\nFinal response:\n{$finalContent}\n";

assert($deltaCount > 0, 'Expected at least one streamed delta');
assert($assembled !== '', 'Expected non-empty assembled content');
assert(Str::contains($assembled, $expectedPhrase, false), 'Expected phrase in streamed content');
assert(Str::contains($final->content(), $expectedPhrase, false), 'Expected phrase in final content');
assert(trim($assembled) === trim($finalContent), 'Expected assembled content to match final content');
?>