feat(core): add reverse prop to useTransition

[joshuaellis]

Closes #1794.

useTransition lost the v8-era transition.reverse() capability when the API became a render function. There is no built-in way today to make items trail forward on enter but backward on leave; the existing sort prop reverses display order, not trail delay order.

Approach

Adds reverse?: boolean to UseTransitionProps. When true, the order in which trail delays are assigned is flipped so the last visible item starts first and the trail accumulates backward across the remaining items. Toggle it with caller state (e.g. reverse: !open) to flip behaviour between enter and leave phases.

reverse is scoped to trail delay assignment only — render order is untouched, and sort remains the prop for display order. Two orthogonal concerns, two props. Backwards-compatible default false.

Items that don't actually transition this render (stable items with no update prop, items already mid-leave) stay outside the trail accumulator, so reverse only flips the items that are animating — same scope as trail itself.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
react-spring	Error		May 22, 2026 11:27am

[changeset-bot]

🦋 Changeset detected

Latest commit: b27ff7e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 13 packages

Name	Type
@react-spring/core	Minor
react-spring	Patch
@react-spring/konva	Minor
@react-spring/native	Minor
@react-spring/three	Minor
@react-spring/web	Minor
@react-spring/zdog	Minor
@react-spring/animated	Minor
@react-spring/mock-raf	Minor
@react-spring/parallax	Minor
@react-spring/rafz	Minor
@react-spring/shared	Minor
@react-spring/types	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR