check whether the current session is still authenticated

probes the cached session cheaply: when a cached blueprint offers a known protected file path, a HEAD request against it (deterministic first entry, no body transfer) decides; otherwise the login page is requested once and inspected. the probe never scrapes the archive, never downloads a data file, and never touches the random number generator (the previous implementation did all three). returns FALSE if the session has expired or was never established.

Usage

liss_is_logged_in()

Value

logical scalar.

Examples

if (FALSE) { # \dontrun{
liss_login()
liss_is_logged_in()
} # }