[stephencanon]

Worth pointing out that we're already using this in the OS for "real work", so we consider it to be production-usable, despite the 0.x tag. The pre-1.0 tag is really about the fact that we expect to make some changes to the high-level patterns as we do more to adopt Span-based APIs over the coming months.

Which means, yes, using it now is signing up for some source breaks, but they won't be too abrupt and this is considerably more stable than a typical first 0.x release would be.