What problem does it solve? Animation code often ships with subtle craft defects—sluggish easing, wrong transform origins, non-GPU properties, missing reduced-motion handling—that make interfaces feel slow or broken even when they technically work. This Skill reviews motion code against a strict, opinionated bar derived from Emil Kowalski's design engineering philosophy, flagging regressions instead of rubber-stamping them. ## Core Features & Use Cases - Ten non-negotiable standards: Checks justified motion, frequency-appropriateness, responsive easing, sub-300ms durations, origin correctness, interruptibility, GPU-only properties, accessibility, asymmetric timing, and cohesion. - Hard escalation triggers: Instantly flags transition: all, scale(0) entrances, ease-in on UI, keyframes on toasts, layout-property animation, and ungated hover motion. - Structured output: Produces a Before/After/Why findings table plus a tiered verdict ending in an explicit Block or Approve decision, citing exact values from STANDARDS.md. - Use Case: A developer opens a pull request adding a dropdown that animates with ease-in over 400ms from transform-origin: center. The review flags the easing, duration, and origin, and prescribes ease-out with a custom cubic-bezier at 150–250ms scaling from the trigger. ## Quick Start Ask the AI to review the animation and motion code in your current diff or pull request against the animation craft standards.
