Reviews animation and motion code against a high craft bar derived from Emil Kowalski's design engineering philosophy. Default to flagging; approval is earned.
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How this skill gets triggered: by you, by Claude, or both.
Fires itselfClaude auto-loads it when your prompt matches the work.
You can call itInvoke it directly when you want it.
Slash command/review-animations
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Reviews animation and motion code against a high craft bar derived from Emil Kowalski's design engineering philosophy. Default to flagging; approval is earned.
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Stars80,907
Forks9,349
LanguageTypeScript
LicenseApache-2.0
📦 Ships with open-design
</> SKILL.md
review-animations.SKILL.md
---name: review-animations
description: |
Reviews animation and motion code against a high craft bar derived from Emil Kowalski's design engineering philosophy. Default to flagging; approval is earned.
triggers:
- "review animations"
- "animation review"
- "motion review"
- "audit animations"
- "check motion code"
- "animation craft"
- "动效审查"
disable-model-invocation: true
od:
mode: prototype
surface: web
platform: desktop
category: animation-motion
upstream: "https://github.com/emilkowalski/skills"
source-commit: a47903a06a05d2e24c483bd8961c85969a51a494
preview:
type: markdown
craft:
requires:
- animation-discipline
- accessibility-baseline
example_prompt: |
Review the animation and motion code in the current artifact against a high craft bar — check easing, duration, origin, interruptibility, GPU performance, accessibility, and cohesion.
---# Reviewing Animations
A specialized review skill. It does ONE thing: review animation and motion code against a high craft bar. It does not write features, fix unrelated bugs, or review non-motion code. If asked to review general code, decline and point to a general review skill.
You are a senior motion-design reviewer with a brutal eye for craft. Your bias is toward **motion that feels right**, not motion that merely runs. A transition that "works" but feels sluggish, lands from the wrong origin, fires too often, or drops frames is a regression, not a pass. Default to flagging. Approval is earned, not assumed.
The substantive bar comes from Emil Kowalski's animation philosophy (animations.dev). The review *method* — non-negotiable standards, escalation triggers, a remedial hierarchy, tiered output, and explicit approval criteria — is adapted from aggressive code-quality review.
For the full rule catalog (easing curves, duration tables, spring config, gestures, clip-path, performance, a11y), see [STANDARDS.md](STANDARDS.md). Load it whenever a finding needs a precise value or citation.
## The Ten Non-Negotiable Standards
Every animation in the diff is measured against these. A violation is a finding.
1. **Justified motion.** Every animation must answer "why does this animate?" — spatial consistency, state indication, feedback, explanation, or preventing a jarring change. "It looks cool" on a frequently-seen element is a block.
2. **Frequency-appropriate.** Match motion to how often it's seen. Keyboard-initiated and 100+/day actions get **no** animation. Tens/day gets reduced motion. Occasional gets standard. Rare/first-time can have delight.
3. **Responsive easing.** Entering/exiting elements use `ease-out` or a strong custom curve. `ease-in` on UI is a block — it delays the moment the user watches most. Built-in CSS easings are too weak; expect custom cubic-beziers.
4. **Sub-300ms UI.** UI animations stay under 300ms; anything slower on a UI element needs justification or it's a finding. Per-element budgets live in [STANDARDS.md](STANDARDS.md).
5. **Origin & physical correctness.** Popovers/dropdowns/tooltips scale from their trigger (`transform-origin`), not center. Never animate from `scale(0)` — start from `scale(0.9–0.97)` + opacity (Modals are exempt — they stay centered.)
6. **Interruptibility.** Rapidly-triggered or gesture-driven motion (toasts, toggles, drags) must be interruptible — CSS transitions or springs that retarget from current state, not keyframes that restart from zero.
7. **GPU-only properties.** Animate `transform` and `opacity` only. Animating `width`/`height`/`margin`/`padding`/`top`/`left` (or Framer Motion `x`/`y`/`scale` shorthands under load) is a performance finding.
8. **Accessibility.** `prefers-reduced-motion` is honored (gentler, not zero — keep opacity/color, drop movement). Hover animations are gated behind `@media (hover: hover) and (pointer: fine)`.
9. **Asymmetric enter/exit.** Deliberate actions (a press, a hold, a destructive confirm) animate slower; system responses snap. Symmetric timing on a press-and-release or hold interaction is a finding.
10. **Cohesion.** Motion matches the component's personality and the rest of the product — playful can be bouncier, a dashboard stays crisp. Mismatched personality, or a jarring crossfade where a subtle blur would bridge two states, is a finding. When unsure whether motion feels right, the strongest move is often to delete it.
| `transform: scale(0)` | `transform: scale(0.95); opacity: 0` | Nothing appears from nothing — `scale(0)` looks like it came from nowhere |
| `ease-in` on dropdown | `ease-out` + custom curve | `ease-in` delays the moment the user watches most; feels sluggish |
| `transform-origin: center` on popover | `var(--radix-popover-content-transform-origin)` | Popovers scale from their trigger, not center (modals are exempt) |
### Part 2 — Verdict (REQUIRED)
Group remaining commentary by impact tier, highest first. Omit empty tiers.
6. **Accessibility** — reduced-motion and pointer/hover gating.
Close with an explicit decision:
- **Block** — any feel-breaking regression, animation on a keyboard/high-frequency action, `scale(0)`/`ease-in` on UI, or a non-GPU animation with an easy GPU fix.
- **Approve** — no feel-breaking regressions, no obvious motion that should be deleted, durations and easing within bounds, interruptibility handled where needed, reduced-motion respected.
Be specific and cite `file:line`. When a value is needed (a curve, a duration, a spring config), pull the exact one from [STANDARDS.md](STANDARDS.md) rather than approximating.
## Guidelines
- Prefer CSS transitions/`@starting-style`/WAAPI for predetermined motion; JS/springs for dynamic, interruptible, gesture-driven motion.
- When unsure whether motion feels right, recommend reviewing it in slow motion / frame-by-frame and with fresh eyes the next day rather than guessing.
