Is the datetime picker in the UI meant to grey out (and not allow selecting) dates in the past, or is that a bug?

I guess for dates in the past, you would need to enter the parameter value as string data type. If you do it often and it’s important to you, I could open a Github issue in the UI repo.

yeah. Not important to me - I usually just use the JSON - but unexpected behaviour/constraint. IMO worth an issue - the constraint is set in https://github.com/PrefectHQ/ui/blob/89735d25de76377575c86e94c25774e644faafef/src/components/RunConfig/DateTimeSelector.vue#L300 from my exploring

nice work finding it! I’ll ask the UI team