fix(core): run async script to to completion under skipAnimation#2438
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When `Globals.skipAnimation` was true, an async script `to` (e.g. `enter:
() => async next => await next({ opacity: 1 })`) bailed before applying any
values, so the spring never reached its declared end state. Apply each step
with `immediate: true` and let the script run to completion so the spring
lands on the final `next(...)` value just like it would with animations on.
A 1024-call safety cap protects against unterminating scripts that would
otherwise become a tight microtask loop without animation frames to pace them.
Closes #1429
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This was referenced May 21, 2026
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Closes #1429.
When
Globals.skipAnimationis true, async functiontos (e.g.enter: () => async next => await next({ opacity: 1 })) should land on the same end state as if animations had run normally — that's how the reduced-motion contract is documented in useReducedMotion. Today they don't:runAsyncshort-circuits before the script ever callstarget.start, so values declared inside the script are silently dropped. Users have had to detectskipAnimationthemselves and rewrite their async chains as flatimmediate: trueobjects (workaround in the thread).Behaviour now
runAsync.animate()applies eachnext(...)call withimmediate: trueand lets the script run through to completion. End states underskipAnimation:toshape{ x: 2 }x === 2(unchanged)[{ x: 1 }, { x: 2 }]x === 2async next => { await next({ x: 1 }); await next({ x: 2 }) }x === 2async next => { while (true) await next({ x: n++ }) }nextcallsThe 1024-call cap
Without animation frames to pace it,
while (true) await next(...)becomes a tight microtask loop that would hang the host. The cap is generous enough to be invisible for real chains and acts as a hard stop for runaway scripts. If you want repeating animations, use theloopprop — it does the right thing underskipAnimation.Behavioural change to be aware of
Previously, setting
skipAnimationmid-flight would abort the async script on its nextawait next(...). It now lets the script finish naturally — each remaining step jumps to its target instead of being skipped over. In-flightSpringValueanimations are unchanged: they still ride out their remaining frames (the global flag is only checked when a new animation starts).