springy-motionlisted

# springy-motion Beautiful motion is not decoration. It is the explanation of what just happened, in the language of physics the body already speaks. This skill builds and reviews motion that *orients, gives feedback, and shows relationships* — and nothing that doesn't. It is opinionated: one perceptual spring model (`duration` + `bounce`), five named presets, and a small set of rules synthesized from the best interaction-design writing (Kowalski, Benji's *Family Values*, Rauno's *Invisible Details* — see `SOURCES.md`). Every number was verified against primary docs and tuned by eye in a real gallery. ## The two jobs ### A. Implement motion 1. **Name the interaction** and find it in the recipe catalog (`references/recipes-web.md`, `references/recipes-swiftui.md`). 2. **Pick the preset by frequency** (rule below). High-frequency/keyboard → less motion. Rare/high-impact → more delight. 3. **Use the recipe's code** for the target platform. Adjust the preset, not the structure. 4. **Add the reduced-motion variant** — it ships with every recipe. Not optional. 5. **Animate only `transform` + `opacity`.** If you reached for `width`/`top`/`margin`, stop. ### B. Review motion Run `references/review-checklist.md` against the code. Report **blockers** (layout-prop animation, no reduced-motion, non-interruptible gesture, naive 0→1, destructive-commit-mid-gesture) first, then smells, then nits. Give each finding its principle and the corrected snippet. ## The spring presets (memoriz