Provide a new API method
Live.getLastVisitorIDs (or similar), that returns a list of the latest visitor IDs (maybe sorted by the date of their last visit as default)
The API method should fully support segmentation, so it is possible to search for specific users.
Note it is already possible to get the list of Visitor IDs with support for segments, by leveraging the existing API
?module=API&method=Live.getLastVisitsDetails and appending
Correct. But that report contains duplicate visitor IDs. Also it processes the complete visit details which is not necessary and takes quite long.