/layers-conceptual-model

Assumes /layers-intro has been loaded. This skill is a library of techniques, not a script — see "How to use these skills" there.

The conceptual model is the most neglected load-bearing layer. It defines the objects the product recognises, how they relate, what states they can be in, and the vocabulary for all of it — a deliberate decision about how the product models its domain, independent of any interface.

It is not the users' messy mental model (that's the domain layer), and not a database schema, wireframe, or flow. But the gap between this model and what engineers build matters: a large, unexamined gap is both UX debt (users meet a product that contradicts the model) and technical debt (the system is hard to evolve).

The decisions this layer makes

• What objects the product recognises, and where each object's boundary is
• How those objects relate — cardinality, and named roles where an object plays several
• What a user can do to or with each object
• What states an object can be in, and which transitions matter
• The product's vocabulary — one name per concept, one concept per name

If none of these is genuinely open, you may not need this layer right now. Say so rather than working it for the sake of it.