From 2c8aeb5e550fdff6e06ac94136434305eac0cbfc Mon Sep 17 00:00:00 2001
From: Peter Abbondanzo <abbo@meta.com>
Date: Mon, 30 Mar 2026 22:08:06 -0700
Subject: [PATCH] Fix Fabric shadow tree not syncing after native-driven
 animation completes

Summary:
When `cxxNativeAnimatedEnabled` is true but `useSharedAnimatedBackend` is false, the JS-side `scheduleUpdate()` call in `useAnimatedProps` was being skipped on animation completion. The code assumed the C++ shared animation backend would handle syncing the shadow tree, but that path only runs when `useSharedAnimatedBackend` is also true.

This left a gap where neither the JS side nor the C++ side synced the Fabric shadow tree after a `useNativeDriver: true` animation completed. The shadow tree retained stale animation values (e.g. `translateX: 100` from a slide-in animation), causing `measure()` to return incorrect coordinates. On VR, this broke Pressability hit-testing for controller input since the measured responder region didn't match the actual view position.

The fix adds `useSharedAnimatedBackend` as an additional condition, so `scheduleUpdate()` only gets skipped when both flags are true (meaning the C++ `AnimationEndSync` path is actually active).

Changelog: [Internal]

Differential Revision: D98808989
---
 .../src/private/animated/createAnimatedPropsHook.js        | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/packages/react-native/src/private/animated/createAnimatedPropsHook.js b/packages/react-native/src/private/animated/createAnimatedPropsHook.js
index 0d5745be8fe1..cc06c8682f89 100644
--- a/packages/react-native/src/private/animated/createAnimatedPropsHook.js
+++ b/packages/react-native/src/private/animated/createAnimatedPropsHook.js
@@ -61,6 +61,8 @@ export default function createAnimatedPropsHook(
     const [, scheduleUpdate] = useReducer<number, void>(count => count + 1, 0);
     const onUpdateRef = useRef<UpdateCallback | null>(null);
     const timerRef = useRef<TimeoutID | null>(null);
+    const sharedAnimatedBackendEnabled =
+      ReactNativeFeatureFlags.useSharedAnimatedBackend();
 
     const rootTag = useContext(RootTagContext);
 
@@ -136,7 +138,8 @@ export default function createAnimatedPropsHook(
             // Check 2: this is an animation driven by native.
             // In native driven animations, this callback is only called once the animation completes.
             const shouldRemoveJsSync =
-              ReactNativeFeatureFlags.cxxNativeAnimatedEnabled();
+              ReactNativeFeatureFlags.cxxNativeAnimatedEnabled() &&
+              sharedAnimatedBackendEnabled;
             if (isFabricNode && !shouldRemoveJsSync) {
               // Call `scheduleUpdate` to synchronise Fiber and Shadow tree.
               // Must not be called in Paper.
@@ -212,7 +215,7 @@ export default function createAnimatedPropsHook(
           }
         };
       },
-      [node],
+      [node, sharedAnimatedBackendEnabled],
     );
     const callbackRef = useRefEffect<TInstance>(refEffect);