Now about the present: this afternoon, I opened up the folder with the old syllabus for one of this fall's classes for to begin the long, slow process of figuring out assignments and timing.
It was already filled in with correct dates and updated assignments--woo hoo! There's still a lot left to do, but there's a lot less than I thought there'd be.
Either the Syllabus Fairy got to this folder before I did, or I worked on it back when I ordered books and then forgot that I'd done so.
So to the Syllabus Fairy or to the May incarnation of Undine or whoever did this: thanks from August Undine.
[Updated to add: see also More or Less Bunk's take on the tenure/deadwood idea: "This is the academic politics of distraction writ large. Don’t blame us, blame the senile old fogey over there."]