we looked into several ways of tackling this. Unfortunately the app_id field is used in our company to track the webapp / ios / android / service version that fires the event, and is therefore not usable for that purpose.
I guess what we are looking for would be a way to attach labels to events like “passive / active” or “on-site / offsite” or “engagement” etc. We could add this “meta” information into contexts or any se_* field, but managing those labels (applying them on historical data for instance) can be a touchy operation.
For now we are thinking of simply building a reference table with the labels we need. But maybe this could be part of a more global feature where we document each event we fire (with versioning, historical compatibility, labels etc). We’ll test some stuff internally and will let you know if we find a scalable / easy-to-maintain (for both analysts and frontend devs) method.