Demo — Composing Observers¶

The script examples/event_observers_demo.py shows how to combine observers for logs, metrics, and JSONL.

Running:

• Ensure the output folder exists or use a JsonlRunObserver that creates parents automatically.
• Execute: python examples/event_observers_demo.py
• Expected output: info logs and a printed overall acceptance rate; JSONL lines at runs/demo/events.jsonl.

Code sketch:

• Create a SimpleEventEmitter
• Create LoggingObserver, MetricsObserver, and JsonlRunObserver
• Wrap the JSONL observer in a context manager
• Register a CompositeObserver ([...])
• Emit example events (dense candidates, reranker score, triple committed)

Tips:

• Add LangfuseObserver to the composite when Langfuse is configured to see spans.