Right now, the Browser Session Id is not available on X++, at least not consistently, or it isn't documented adequately how to get this information. When trying to track processes, especially for telemetry purposes, this information would be helpful, as it connects various individual Server-side activites (each with their own ActivityId) to a consistent whole. Also, LCS provides this information for the same purpose.

The standard telemetry should add this browser session ID consistently to all entries, so that one can analyse the telemetry of a given session more effectively.

In either case, make this value available for consumption in custom modules as well, please do not hide it in internal code. This would allow advanced monitoring in special cases by custom code.