🇨🇦 SteveI guess I can bisect to find where it all went wrong, archiving at every revision.
That's gonna suck.
*sighs, gets started*
Looks like I made my command line tool part of the xcscheme. Good idea, terrible side effect. Reverted!
But reverting wasn't enough. Perhaps there's a file covered by gitignore messing it up. Re-adding the entry to the xcscheme and setting buildForArchiving = "NO" fixed it. That change can be committed.
Michael Fey 
@tewha Did you recently add in a new target? If it’s not being linked into the main target properly Xcode will archive it as an Other Item.
@MrRooni Not added to the project, but recently included in the xcscheme. I've got a command line tool I can use to query the data the app uses. That was it.
Bit of a bummer because I do want it built every time, but it doesn't need to be part of the archive (it'd be nice if it could be) and it shouldn't affect upload.
For now I've just removed it from the scheme.