The problem and suboptimal workaround solution are described here. Basically, we have an ArcGIS Pro add-in that logs metadata about your geoprocessing activity in Pro. By listening to project items changed events we know that a geoprocessing tool has been started, but we can't get any information about the tool parameters or messages it outputs. These parameters and messages are present in the SDK as HistoryProjectItems, but part of a sealed class that cannot be publicly accessed.
The geoprocessing history gets written out to the aprx file when a project is saved, but tearing that file apart to find the relevant geoprocessing history parameters requires that we wait until a user has saved to access that information. Allowing public access to HistoryProjectItems from the SDK would make the process much more robust and reliable.
