[Bug]: Default spring keeps running ~200 ms after the sheet has settled on Reanimated 4 (restDisplacementThreshold / restSpeedThreshold are ignored) #2799

Version

v5

Reanimated Version

v3 (the form has no v4 option: seen on Reanimated 4.7.1, and on 4.1.1 in the snack)

Gesture Handler Version

v2 (the form has no v3 option: seen on Gesture Handler 3.3.0, and on 2.28 in the snack)

Platforms

iOS, Web

What happened?

On Reanimated 4 the library's default spring takes about 680 ms to finish, although the sheet is within a pixel of its target after about 430 to 500 ms. Until the spring finishes, onChange / onClose / onDismiss have not fired, a modal has not unmounted, and a BottomSheetBackdrop still takes touches (its touchability follows animatedIndex reaching disappearsOnIndex). So a tap on the screen right after a sheet has visibly closed is swallowed.

Cause. The default spring in src/constants.ts (the default on iOS, and on web since v5.2.0) is told when to stop with restDisplacementThreshold: 10 and restSpeedThreshold: 10. Reanimated 4 removed both options (migration guide): withSpring now stops by a relative energyThreshold (default 6e-9) and silently ignores the two old keys. The same two keys are in src/utilities/getKeyboardAnimationConfigs.ts (the keyboard easing). Both are unchanged in v5.2.14 and on master.

Measured in the snack below (web, Reanimated 4.1.1), time from snapToIndex(0) / close() to onChange:

Calculated by stepping Reanimated's own spring functions with the library's spring at 60 fps, for a travel of 300 to 800 px:

Android is not affected: its default is the 250 ms timing.

Workaround. Pass the same spring with an explicit threshold:

<BottomSheet
  animationConfigs={{
    damping: 500,
    stiffness: 1000,
    mass: 3,
    overshootClamping: true,
    energyThreshold: 1e-5,
  }}
/>

This does not reach keyboard-driven moves, which take their config from getKeyboardAnimationConfigs.

Suggested fix. In both files, replace the two removed keys with energyThreshold when running on Reanimated 4.

Reproduction steps

• Open the snack on web (or iOS).
• Press "Next animationConfigs" once, so it reads "library spring". Press "Open", then "Close": onChange fires about 680 ms after each call.
• Press "Next animationConfigs" again ("spring + energyThreshold") and repeat: about 460 ms, with the same visible motion.
• On iOS the first setting, "library default", shows the same 680 ms. On web it only does from v5.2.0, where the spring became the web default; the snack is on v5.1.7 (see the note below).

Reproduction sample

snack.expo.dev: gorhom spring ends late on Reanimated 4

Note on the snack's version: it pins v5.1.7 because Snack cannot bundle v5.1.8 or later. Its bundler answers Snack does not support non-semver version references, found: "react-native-reanimated" = ">=3.16.0 || >=4.0.0-", so no release that declares Reanimated 4 support loads in Snack at the moment. The spring config is the same in v5.1.7 and v5.2.14.

Relevant log output

No response