Version-sensitive. Every API name, SDK gate and browser-support claim below was verified on 2026-09-08 against primary sources. What against, and when, is in _jutsu/VERSIONS.md. If that date is old, re-verify before acting on a version number.

Desktop Principles

Desktop UX context. Loaded when desktop is detected (macOS, Windows, Linux desktop, web desktop). Concise rules here. Deep-dive in references/.

Hover States Are Mandatory

Hover is the primary affordance signal on desktop, the inverse of mobile. A pointer hovering over a target without immediate visual feedback feels broken: users rely on :hover to confirm an element is interactive before committing to a click. Every clickable surface must have a distinct hover style, ideally with a 100-200ms transition so the change is perceptible without feeling sluggish.