As promised.

https://github.com/lsst/pex_config/pull/96

Will start Jenkins a bit later; I suspect main is broken from attempts on a different branch, and I want to chase that down first.

Jenkins says we need changes in dax_apdb, so here they are: https://github.com/lsst/dax_apdb/pull/33

Would not be surprised to find more of those.

I'm bailing out on this and closing the ticket as Won't Fix for now, as the downstream breakage makes it not worth it, even if the problem is real.

I'm leaving the branch around, but it requires the annotation to be consistent with the value of optional already, and I think we need to instead try to find a way to let

Field[int]("field a", optional=True)

imply that the field value is int | None rather than int. That will fix existing code rather than forcing existing code to be fixed.

It's at least a lot harder to do that, and it may be effectively impossible; I think it'd have to involve a lot of typing.overload on Field constructors.