Just had to take a moment to whine about the worst day of my internship.
I was continuously interrupted yesterday morning (tax assessors, repairman - for needed repairs, etc.), and didn't get started until late. So, feeling obligated, I worked late, and did something stupid. I didn't realize how stupid until this morning, when my system wouldn't boot because it was unable to find the root directory of my logical volume. About that point, I panicked - a seriously not useful response.
I built a thumb drive with a bootable ubuntu from my Windows PC (with debian I would have had to install it). Fortunately, all my files are still there, but I could only figure out how to access them from the File Manager. I backed up the code I've written to 2 pen drives.
I took a bunch of walks. Then I figured out how to access my files from Terminal, running as root. Now I'm rebuilding Linux from what I got from the Torvald Linux github. And I have a recipe for installing it so that's what will boot.
Before the next step, I think at the very least, I'll put everything (my files, Linux, xen, even /usr) back up on git, and, if I have to, I can restore everything, by re-installing, and getting stuff from git. Not optimal, to say the least, especially so close to the end.