A preview of a project to finish, however, not without the mandatory teeth-gnashing...! Yes, I did it again--a goof, that is. I don't recall making this particular goof before, so I'm chalking it up to #834.
#834: Look again before you sew. As I was admiring my handiwork of kitchener stitching the shoulder seam, I noticed beside me the front section, while the shoulder seam was on the back section that I was holding... Hmmm. A quick reset/sigh and I realized I had sewn the two shoulders together on the back piece. An hour later, I had picked apart my impeccable woven-in ends and the kitchener stitches and was back on track.
If you can't make sense of what I did, here's one more explanation: Take the right shoulder seam from the back and sew it to the left shoulder seam from the back. It only works if you want side seams down the middle of the front and back.