Observability

[sandstrom]

I think it would be good to try to sketch out what the observability functionality for langchainrb might look like.

My understanding is that there isn't an obvious open standard for this, but some efforts/contenders.

• opentelemetry has preliminary work (https://github.com/open-telemetry/community/blob/1c71595874e5d125ca92ec3b0e948c4325161c8a/projects/llm-semconv.md)
• https://github.com/traceloop/openllmetry (controlled by traceloop but seems fairly open)
• https://github.com/openlit/openlit (tied to a company too)

I think a likely good first step would just be to add the instrumentation to this library, and then let users just subscribe to needed events and feed the data to whatever.

I'd suggest using EventReporter or Instrumentation from ActiveSupport.

A second step might be to also start emitting data from this in-library instrumentation in a standardised format, such as one of those mentioned above (though I think more evaluation/research of those is needed first, because I'm not sure either of them is going to end up as a real standard).