Jamie Mill

Defines the product's objects, relationships, states, and vocabulary independently of any interface — the most load-bearing layer

Techniques for mapping a domain's concepts, terminology conflicts, and bounded contexts — the raw material the conceptual model is built from

Techniques for mapping interaction structure and flow — places, affordances, edge cases, and failure paths — without committing to visual form

Techniques for auditing and deciding the surface against the layers below — vocabulary, object consistency, completeness, feedback, hierarchy, accessibility

Framework orientation for Layers of Product Design — load this first; provides the context all other skills depend on

Diagnostic audit across all seven layers — identifies the bottleneck layer and recommends where to focus

Techniques for connecting user opportunities to business outcomes and solution bets, and testing the riskiest assumptions cheaply

Elicits and prioritises user needs (needs, pains, desires) as job stories — produces opportunities ready for product strategy

Techniques for planning user research and synthesising it into grounded, confidence-rated findings about what users actually do