I planned to tackle this in light of my germ layer concept, in which I argue there should probably be three “types” of tools within the editor available depending on the player’s evolutionary path: soft-bodied tools for diploblastic and mollusk/worm-esque organisms, exoskeleton tools for animals with an chitinous exoskeleton akin to arthropods, and internal structure tools editing bones for animals akin to vertebrates.
Segmentation would have to be a cornerstone of the middle, exoskeleton based organisms; it is less explicit in vertebrates, only seen in things like assigning individual spine columns.
So perhaps the discussion shouldn’t necessarily be “how do we implement segmentation” but more how do we accurately represent each “path” of life in the editor and what benefits and detriments will be assigned to soft-bodied, endoskeleton, and exoskeleton organisms. That way, we can accurately structure our thoughts and not be overwhelmed with very specific structural phenomena we see in metazoans.
And before I forget, here is a semi-related community post I think would be valuable to understand: Questions about the realistic implementation of repeating parts/segments (and Williston's law) - Multicellular Stage - Thrive Community Forum