"Flight recorders" for protocols?

[LPardue]

Related to observability and monitoring but possibly outside the scope of this document, some input to figure out would be appreciated.

Imagine the scenario where in a local implemenation a protocol problem arises, such as breaking on an unexpected sequence of protocol elements, due the peer exercising greasing or variability. The affected party might want to get an understanding of what went wrong without having to do any more coordination with the peer. An ability to log the specific details of protocol elements can help with root cause analysis and reproducibility, aka exemplars. qlog is an example of a logging format that could be used to record details under error circumstances. And like a flight recorder box, perhaps privacy-preserving exemplars could be shared with various parties to help investigation and understanding of whether there are other systematic issues.