I managed to get this to work:
setHook("rstudio.sessionInit", function(newSession) {
if (newSession) {
message("Welcome to RStudio ", rstudioapi::getVersion())
}
ap <- rstudioapi::getActiveProject()
if (is.null(ap)) ap <- "No active project"
message("Active RStudio project: ", ap)
}, action = "append"
)