A treat, we believe! It wasn't in fact an email but a short 'welcome' SMS from her future boss. So I think a Halloween 'trick' can be ruled out.
It is great that on just this weekend Jessi has her mother visiting and their afternoon expedition was to Ikea on the other side of the park which was once Tempelhof airfield.
Which of course reminds me of my stints in the neighbourhood, my workplace in 1963 and again in 1993 just below the bottom margin of the image above at the UFA. Studios.