Looking to keep the valid data as well, instead of replacing the entire value tree with a default

Figured since spec is already traversing the data, it can save having to manually do it again when validation errors are detected, but unsure how to approach it

No, spec is a validation library, not a transformation library

Ah good to know, thanks! Are you aware of a library providing such transformations?

Maybe you could leverage s/explain-data

Metosin's spec-tools perhaps https://github.com/metosin/spec-tools?tab=readme-ov-file#spec-tools--

Spec-tools is interesting! I'll look into it, thank you!