What problem does it solve? Users blame themselves when a product is confusing, but the fault is almost always the design. This Skill gives you a structured diagnostic framework to locate exactly why an interface fails — a broken affordance, a missing signifier, an arbitrary mapping, absent constraints, silent feedback, or a mismatched conceptual model — and name the category of fix. ## Core Features & Use Cases - Two Gulfs Analysis: Walk the Gulf of Execution and Gulf of Evaluation for any task to find where users get stuck. - Seven-Principle Diagnosis: Systematically check discoverability, affordances, signifiers, mappings, constraints, feedback, and conceptual models against reference guides. - Error Classification: Distinguish slips from mistakes, trace each to its design cause, and layer defenses (constraints, warnings, feedback, undo, recovery). - Use Case: Users keep deleting the wrong item in your app. Walk the seven stages of action, classify the error as an adjacent-target slip, and fix it with distance, distinct styling, and undo instead of another confirmation dialog. ## Quick Start Ask the AI to diagnose why users keep making a specific mistake in your interface using Norman's usability principles.
