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Overview

This example shows how to export Instructor runtime telemetry to Langfuse while keeping the example itself simple. It wires the existing event bus into the telemetry projectors and then runs one small structured extraction. Key concepts:
  • RuntimeEventBridge: attaches telemetry projection to the runtime event bus
  • LangfuseExporter: sends canonical telemetry to Langfuse over HTTP
  • InstructorTelemetryProjector: maps structured output lifecycle events
  • PolyglotTelemetryProjector: captures the nested LLM inference spans
  • HttpClientTelemetryProjector: captures outbound HTTP spans

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Example

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

use Cognesy\Events\Dispatchers\EventDispatcher;
use Cognesy\Http\Telemetry\HttpClientTelemetryProjector;
use Cognesy\Instructor\StructuredOutput;
use Cognesy\Instructor\StructuredOutputRuntime;
use Cognesy\Instructor\Telemetry\InstructorTelemetryProjector;
use Cognesy\Polyglot\Inference\LLMProvider;
use Cognesy\Polyglot\Telemetry\PolyglotTelemetryProjector;
use Cognesy\Telemetry\Application\Projector\CompositeTelemetryProjector;
use Cognesy\Telemetry\Application\Projector\RuntimeEventBridge;

class SupportTicket
{
    public string $priority;
    public string $summary;
}

$events = new EventDispatcher('examples.a03.telemetry-langfuse');
$hub = exampleLangfuseHub();

(new RuntimeEventBridge(new CompositeTelemetryProjector([
    new InstructorTelemetryProjector($hub),
    new PolyglotTelemetryProjector($hub),
    new HttpClientTelemetryProjector($hub),
])))->attachTo($events);

$runtime = StructuredOutputRuntime::fromProvider(
    provider: LLMProvider::using('openai'),
    events: $events,
);

$ticket = (new StructuredOutput($runtime))
    ->with(
        messages: 'Customer report: The checkout page returns a 500 error after payment. Treat this as urgent and summarize it in one sentence.',
        responseModel: SupportTicket::class,
    )
    ->get();

$hub->flush();

echo "Priority: {$ticket->priority}\n";
echo "Summary: {$ticket->summary}\n";
echo "Telemetry: flushed to Langfuse\n";

assert($ticket->priority !== '');
assert($ticket->summary !== '');
?>