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Overview

This example shows the smallest opt-in file logging flow with EventLog::enable(). It activates the default JSONL sink, runs one StructuredOutput request without passing a custom event bus, then reads the generated log file back and prints the captured entries on screen. Key concepts:
  • EventLog::enable(): turns on the default JSONL sink for the current process
  • StructuredOutputRuntime::fromProvider(...): uses the default runtime event bus
  • JSONL readback: parse the generated file after the request completes

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Example

<?php
require 'examples/boot.php';
require_once 'examples/_support/eventlog_readback.php';

use Cognesy\Instructor\StructuredOutput;
use Cognesy\Instructor\StructuredOutputRuntime;
use Cognesy\Logging\EventLog;
use Cognesy\Polyglot\Inference\LLMProvider;

final class IncidentSummary
{
    public string $severity;
    public string $summary;
}

$logPath = ExampleEventLog::path('examples-a03-structured-output-eventlog');

EventLog::enable($logPath);

try {
    $runtime = StructuredOutputRuntime::fromProvider(LLMProvider::using('openai'));

    $incident = (new StructuredOutput($runtime))
        ->with(
            messages: 'Customer report: checkout returns HTTP 500 after payment. Mark severity and summarize it in one sentence.',
            responseModel: IncidentSummary::class,
        )
        ->get();

    $entries = ExampleEventLog::read($logPath);
} finally {
    EventLog::disable();
}

echo "=== StructuredOutput Result ===\n";
echo "Severity: {$incident->severity}\n";
echo "Summary: {$incident->summary}\n";

echo "\n=== EventLog Entries ===\n";
echo "Log file: {$logPath}\n";
echo 'Entries captured: ' . count($entries) . "\n\n";

ExampleEventLog::print($entries, 8);

assert($incident->severity !== '');
assert($incident->summary !== '');
assert($entries !== []);
?>