Load this skill at the start of any design session. It provides the framework context that all other skills depend on.

Layers of Product Design organises design work into seven layers across three zones. Layers have logical dependency: lower layers are foundations for upper ones. Weak lower layers create UX debt that propagates upward.

Reality — complex, contradictory, evolving. Source of all learning.

Problem space — knowledge gathered from reality:

Solution space — deliberate decisions about what to build: 4. Product & service strategy — which needs to serve, and what business outcomes to target 5. Conceptual model — objects, relationships, states, vocabulary — independent of any interface 6. Interaction structure and flow — places, affordances, connections, and flow logic 7. Surface — words, visuals, feedback, hierarchy — what users actually encounter

The layers are not a linear process. Enter anywhere — but always check whether the foundations below are sound.

Inspired by Jesse James Garrett's The Elements of User Experience (2000).

Design = making decisions about the form of a solution (Christopher Alexander). Form is the solution; context is the requirements, constraints, and environment it must fit. Good design is good fit.

The job of every skill is to help the designer make better decisions — not to make decisions for them.

Temporal decisions are frequently overlooked. They cluster at two layers:

OOUX object failure modes (Sophia Prater):

Nielsen's heuristics — a root-layer mapping: "Match between system and real world" violations almost always root in the conceptual model, not the surface. "User control and freedom" is an interaction structure decision. Patching these at the surface treats symptoms, not causes.

At the start of any design session, ask where to save outputs:

Save the session summary to the chosen destination at the end.

When writing Mermaid diagrams, use for line breaks inside node labels — not , which renders as literal text.

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