fix(shared): preserve decimal precision in string interpolator#2469
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Closes #1461. The string interpolator used `output[0]` as both the value at `input = range[0]` and the template for every other input, so trailing zeros (`'0.00'`), explicit signs, and any other format information on later keyframes were dropped on the round-trip through `numberRegex`. As a result, `useSpring({ from: '0.00', to: '1.50' })` rendered `'0'` at rest and `'1.5'` at the goal. Two-part fix: 1. When `input` lands exactly on a `range` value, return that keyframe's `output[k]` verbatim — fixes initial render and at-rest goal for all formats (decimals, signs, locale separators). 2. Per number-position, when every keyframe shares the same non-zero fractional-digit count, `toFixed(n)` the mid-animation result. Gated on `> 0` so whole-number keyframes (e.g. `rgba(…, 0)` → `rgba(…, 1)`) keep their natural sub-frame precision.
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🦋 Changeset detectedLatest commit: 290788c The changes in this PR will be included in the next version bump. This PR includes changesets to release 12 packages
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This was referenced May 22, 2026
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Summary
Closes #1461. Stringified floats lost their precision through
useSpring—'0.00'rendered as'0','1.50'settled at'1.5', and mid-tween values flickered raw IEEE-754 noise. Springs should respect the text the user wrote.Fix
In
createStringInterpolator: return each keyframe verbatim wheninputlands on it (preserves all formatting at start and goal), and pad mid-animation results to the keyframes' shared decimal count when every keyframe opts in to fractional digits. Padding is gated on a non-zero shared count so whole-number keyframes (notably the alpha channel inrgba(…, 0)→rgba(…, 1)) keep their natural sub-frame precision.Out of scope
#1660's
+sign case has a different root cause (AnimatedString lifecycle). Locale separators like'1.500 kr'mid-tween require.to(formatter)—numberRegexcan't disambiguate them.