Last night I only got around to sewing the sleeve sides together and pressing the seam open in preparation for attaching them to the bodice. That’s when I noticed that I had previously missed the fact that the pattern instructions have the sleeves attaching to the bodice without being closed at the underarm seam first. Instead, the pattern has the sleeves being sewn around the armhole, and then sewn under the arm in a line that continues down the bodice sideseam, closing that seam. But I closed this seam earlier in the process when I decided to leave the sleeves til last thing. I just assumed the instructions skipped the “sew bodice front to bodice back at side seams” step. Oh well. This might be period, but I think it’s a bit weird. There’s no reason not to use a modern sleeve-attachment technique, and since that’s the only option left, that’s what I’m going to do.