We have recently run into two tickets where the errors returned by WT (e.g. EINVAL and WT_ERROR) didn't come with sufficient context for us to decide what to do, uncovering a need for more granular errors from WT. Instances can also occur where the error gets propagated to users in a misleading manner.

WT has an existing event handler mechanism (WT_EVENT_HANDLER) that could be experimented with for this purpose, but while the infrastructure is in place it does not have the full functionality to attach to sessions and obtain/pass us the needed context.

This ticket can investigate a POC to extend the way the event handler currently works to explore passing better error contexts.

Having discussed this issue with agorrod, attached is a diff that he worked on to conceptually demonstrate per-session event handlers. This might be a good place to start.