design-everyday-things

Run the Quick Diagnostic: check if users can figure out what to do, understand what happened, recover from errors, see control-output mapping, and are blocked from invalid options. Each failed row maps to a specific principle (signifiers, feedback, constraints) with concrete fixes.

An affordance is what actions an object can support; a signifier communicates where and how to act. A button affords clicking, while its color, shadow, and label are signifiers showing it is clickable. Good design aligns perceived affordances with real ones.

Use constraints to make errors impossible: date pickers instead of free text, disabled submit until required fields are valid, input masks for phone numbers, and real-time inline validation. Add undo and soft-delete for recovery when errors still occur.

Use this framework for foundational diagnosis of why interactions fail: discoverability, mental models, and the gulfs of execution and evaluation. For heuristic-based usability scoring of interfaces, the Skill itself directs you to a dedicated ux-heuristics skill.

Repeated errors indicate design flaws, not user flaws. Classify the error as a slip (right intention, wrong action) or mistake (wrong intention), then fix the cause: separate destructive actions, show mode state, or correct the misleading conceptual model.