What the browser holds, as R: the events last rendered with
render_el_calendar() or sent with update_el_calendar(), with every
event update_el_calendar() has since inserted, replaced or deleted. The
user's requests (input$<id>_add, ...) are not in it until the server
answers them. A reactive read.
Usage
el_calendar_events(session = shiny::getDefaultReactiveDomain(), id)