Building Animations

SDD gate. If this fired on a new, non-trivial feature or behaviour change and there is no approved spec + plan under 02-DOCS/wiki/sdd/, hand off to ../specify/SKILL.md first — it runs brainstorm → spec → plan → tasks before any code, then routes back here once the plan is approved. Build straight from here only for a genuinely one-line / low-risk change, or a bug fix restoring intended behaviour. Method: ../sdd/SKILL.md.

Hand-offs. The visual system — palette, type scale, spacing, brand grounding, landing composition — is ../design/SKILL.md's; this skill only sets motion. React Native / Expo motion is ../animate-expo/SKILL.md's: no hover, two runtimes, gestures as the baseline. Gesture physics — velocity handoff, momentum projection, rubber-banding, translucent materials — is ../apple-design/SKILL.md's. Reviewing motion someone else wrote is ../review-animations/SKILL.md's. The countable half of the bar below is executable: ../review-animations/scripts/verify.sh flags transition: all, a scale(0) entrance, ease-in on UI, a centered popover origin, and motion with no reduced-motion guard. Run it before you claim the animation is done.

A construction skill. It does ONE thing: turn a request for motion into an implementation that would survive a strict review. It does not audit a codebase (that's improve-animations), critique a diff (that's review-animations), hunt for places that could animate (that's find-animation-opportunities), or build for React Native (that's animate-expo).