From 75cf9c02af57fdf149c340b36329755b8f148ad7 Mon Sep 17 00:00:00 2001
From: Zeya Peng <zeyap@meta.com>
Date: Thu, 5 Feb 2026 18:13:14 -0500
Subject: [PATCH 1/8] enableViewTransition for RN

Summary:
- turn on enableViewTransition feature
- stub shim
- run some mutation config fn at persistence mode too
---
 .../src/ReactFiberConfigFabric.js             | 226 +++++++++++++++++-
 .../src/ReactFiberCommitViewTransitions.js    |   7 +-
 .../src/ReactFiberCommitWork.js               |   2 +-
 .../src/ReactFiberConfigWithNoMutation.js     | 187 +++++++++++----
 .../forks/ReactFeatureFlags.native-fb.js      |   2 +-
 ...actFeatureFlags.test-renderer.native-fb.js |   2 +-
 6 files changed, 371 insertions(+), 55 deletions(-)

diff --git a/packages/react-native-renderer/src/ReactFiberConfigFabric.js b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
index f5a4361fd41d..3c293aca3738 100644
--- a/packages/react-native-renderer/src/ReactFiberConfigFabric.js
+++ b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
@@ -12,6 +12,7 @@ import type {
   TouchedViewDataAtPoint,
   ViewConfig,
 } from './ReactNativeTypes';
+import type {TransitionTypes} from 'react/src/ReactTransitionType';
 import {dispatchEvent} from './ReactFabricEventEmitter';
 import {
   NoEventPriority,
@@ -72,6 +73,12 @@ import {passChildrenWhenCloningPersistedNodes} from 'shared/ReactFeatureFlags';
 import {REACT_CONTEXT_TYPE} from 'shared/ReactSymbols';
 import type {ReactContext} from 'shared/ReactTypes';
 
+export * from 'react-reconciler/src/ReactFiberConfigWithNoHydration';
+export * from 'react-reconciler/src/ReactFiberConfigWithNoScopes';
+export * from 'react-reconciler/src/ReactFiberConfigWithNoTestSelectors';
+export * from 'react-reconciler/src/ReactFiberConfigWithNoResources';
+export * from 'react-reconciler/src/ReactFiberConfigWithNoSingletons';
+
 export {default as rendererVersion} from 'shared/ReactVersion'; // TODO: Consider exporting the react-native version.
 export const rendererPackageName = 'react-native-renderer';
 export const extraDevToolsConfig = {
@@ -157,12 +164,219 @@ if (registerEventHandler) {
   registerEventHandler(dispatchEvent);
 }
 
-export * from 'react-reconciler/src/ReactFiberConfigWithNoMutation';
-export * from 'react-reconciler/src/ReactFiberConfigWithNoHydration';
-export * from 'react-reconciler/src/ReactFiberConfigWithNoScopes';
-export * from 'react-reconciler/src/ReactFiberConfigWithNoTestSelectors';
-export * from 'react-reconciler/src/ReactFiberConfigWithNoResources';
-export * from 'react-reconciler/src/ReactFiberConfigWithNoSingletons';
+// -------------------
+//     Mutation
+// -------------------
+
+function shim(...args: any): empty {
+  throw new Error(
+    'The current renderer does not support mutation. ' +
+      'This error is likely caused by a bug in React. ' +
+      'Please file an issue.',
+  );
+}
+
+export const supportsMutation = false;
+
+export const cloneMutableInstance = shim;
+export const cloneMutableTextInstance = shim;
+export const appendChild = shim;
+export const appendChildToContainer = shim;
+export const commitTextUpdate = shim;
+
+export function commitMount(
+  instance: Instance,
+  type: string,
+  newProps: Props,
+  internalInstanceHandle: Object,
+): void {
+  console.log('[shim] commitMount');
+}
+
+export const commitUpdate = shim;
+export const insertBefore = shim;
+export const insertInContainerBefore = shim;
+export const removeChild = shim;
+export const removeChildFromContainer = shim;
+export const resetTextContent = shim;
+export const hideInstance = shim;
+export const hideTextInstance = shim;
+export const unhideInstance = shim;
+export const unhideTextInstance = shim;
+export const clearContainer = shim;
+
+export type InstanceMeasurement = {
+  rect: {x: number, y: number, width: number, height: number},
+  abs: boolean,
+  clip: boolean,
+  view: boolean,
+};
+
+export type RunningViewTransition = null;
+
+export type ViewTransitionInstance = null | {
+  name: string,
+  ...
+};
+
+export type GestureTimeline = any;
+
+export function restoreViewTransitionName(
+  instance: Instance,
+  props: Props,
+): void {
+  console.log('[shim] restoreViewTransitionName ', instance.canonical.nativeTag);
+}
+
+export function cancelViewTransitionName(
+  instance: Instance,
+  oldName: string,
+  props: Props,
+): void {
+  console.log('[shim] cancelViewTransitionName ', oldName, instance.canonical.nativeTag);
+}
+
+export function cancelRootViewTransitionName(rootContainer: Container): void {
+  console.log('[shim] cancelRootViewTransitionName');
+}
+
+export function restoreRootViewTransitionName(rootContainer: Container): void {
+  console.log('[shim] restoreRootViewTransitionName');
+}
+
+export function cloneRootViewTransitionContainer(
+  rootContainer: Container,
+): Instance {
+  console.log('[shim] cloneRootViewTransitionContainer');
+}
+
+export function removeRootViewTransitionClone(
+  rootContainer: Container,
+  clone: Instance,
+): void {
+  console.log('[shim] removeRootViewTransitionClone');
+}
+
+export function measureInstance(instance: Instance): InstanceMeasurement {
+  console.log('[shim] measureInstance ', instance.canonical.nativeTag);
+  return {rect: {x: 0, y: 0, width: 0, height: 0}, abs: false, clip: false, view: true};
+}
+
+export function measureClonedInstance(instance: Instance): InstanceMeasurement {
+  console.log('[shim] measureClonedInstance ', instance.canonical.nativeTag);
+  return {rect: {x: 0, y: 0, width: 0, height: 0}, abs: false, clip: false, view: true};
+}
+
+export function wasInstanceInViewport(
+  measurement: InstanceMeasurement,
+): boolean {
+  console.log('[shim] wasInstanceInViewport');
+  return measurement.view;
+}
+
+export function hasInstanceChanged(
+  oldMeasurement: InstanceMeasurement,
+  newMeasurement: InstanceMeasurement,
+): boolean {
+  console.log('[shim] hasInstanceChanged');
+  return false;
+}
+
+export function hasInstanceAffectedParent(
+  oldMeasurement: InstanceMeasurement,
+  newMeasurement: InstanceMeasurement,
+): boolean {
+  console.log('[shim] hasInstanceAffectedParent');
+  return false;
+}
+
+export function startGestureTransition(
+  suspendedState: null | SuspendedState,
+  rootContainer: Container,
+  timeline: GestureTimeline,
+  rangeStart: number,
+  rangeEnd: number,
+  transitionTypes: null | TransitionTypes,
+  mutationCallback: () => void,
+  animateCallback: () => void,
+  errorCallback: (error: mixed) => void,
+  finishedAnimation: () => void,
+): RunningViewTransition {
+  console.log('[shim] startGestureTransition');
+  return null;
+}
+
+export function stopViewTransition(transition: RunningViewTransition): void {
+  console.log('[shim] stopViewTransition');
+}
+
+export function addViewTransitionFinishedListener(
+  transition: RunningViewTransition,
+  callback: () => void,
+): void {
+  console.log('[shim] addViewTransitionFinishedListener');
+  callback();
+}
+
+export function createViewTransitionInstance(
+  name: string,
+): ViewTransitionInstance {
+  console.log('[shim] createViewTransitionInstance', name);
+  return {name};
+}
+
+export function getCurrentGestureOffset(timeline: GestureTimeline): number {
+  console.log('[shim] getCurrentGestureOffset');
+  return 0;
+}
+
+export function applyViewTransitionName(
+  instance: Instance,
+  name: string,
+  className: ?string,
+): void {
+  // add view-transition-name to things that might animate for browser
+  console.log('[shim] applyViewTransitionName', name, className, instance.canonical.nativeTag);
+}
+
+export function startViewTransition(
+  suspendedState: null | SuspendedState,
+  rootContainer: Container,
+  transitionTypes: null | TransitionTypes,
+  mutationCallback: () => void,
+  layoutCallback: () => void,
+  afterMutationCallback: () => void,
+  spawnedWorkCallback: () => void,
+  passiveCallback: () => mixed,
+  errorCallback: (error: mixed) => void,
+  blockedCallback: (name: string) => void,
+  finishedAnimation: () => void,
+): RunningViewTransition {
+  console.log('[shim] startViewTransition transitionTypes', JSON.stringify(transitionTypes ?? []));
+
+  // mutation phase
+  console.log('[shim] startViewTransition mutations start');
+  mutationCallback();
+  layoutCallback(); // run layout effects
+  afterMutationCallback();
+  console.log('[shim] startViewTransition mutations finish');
+
+  // browser creates pseudo elements
+  console.log('[shim] startViewTransition pseudo element captured');
+
+  // transition ready
+  console.log('[shim] startViewTransition transition ready');
+  spawnedWorkCallback();
+
+  console.log('[shim] startViewTransition finishedAnimation');
+  // finishedAnimation();
+
+  // transition ends
+  console.log('[shim] startViewTransition transition ends');
+  passiveCallback();
+
+  return null;
+}
 
 export function appendInitialChild(
   parentInstance: Instance,
diff --git a/packages/react-reconciler/src/ReactFiberCommitViewTransitions.js b/packages/react-reconciler/src/ReactFiberCommitViewTransitions.js
index a9edc0c84d23..5431585185dc 100644
--- a/packages/react-reconciler/src/ReactFiberCommitViewTransitions.js
+++ b/packages/react-reconciler/src/ReactFiberCommitViewTransitions.js
@@ -26,6 +26,7 @@ import {
 } from './ReactFiberFlags';
 import {
   supportsMutation,
+  supportsPersistence,
   applyViewTransitionName,
   restoreViewTransitionName,
   measureInstance,
@@ -139,7 +140,7 @@ function applyViewTransitionToHostInstancesRecursive(
   collectMeasurements: null | Array<InstanceMeasurement>,
   stopAtNestedViewTransitions: boolean,
 ): boolean {
-  if (!supportsMutation) {
+  if (!supportsMutation && !supportsPersistence) {
     return false;
   }
   let inViewport = false;
@@ -201,7 +202,7 @@ function restoreViewTransitionOnHostInstances(
   child: null | Fiber,
   stopAtNestedViewTransitions: boolean,
 ): void {
-  if (!supportsMutation) {
+  if (!supportsMutation && !supportsPersistence) {
     return;
   }
   while (child !== null) {
@@ -648,7 +649,7 @@ function measureViewTransitionHostInstancesRecursive(
   previousMeasurements: null | Array<InstanceMeasurement>,
   stopAtNestedViewTransitions: boolean,
 ): boolean {
-  if (!supportsMutation) {
+  if (!supportsMutation && !supportsPersistence) {
     return true;
   }
   let inViewport = false;
diff --git a/packages/react-reconciler/src/ReactFiberCommitWork.js b/packages/react-reconciler/src/ReactFiberCommitWork.js
index 08882a04766c..4b4531c863e1 100644
--- a/packages/react-reconciler/src/ReactFiberCommitWork.js
+++ b/packages/react-reconciler/src/ReactFiberCommitWork.js
@@ -3709,7 +3709,7 @@ function commitPassiveMountOnFiber(
       }
 
       if (isViewTransitionEligible) {
-        if (supportsMutation && rootViewTransitionNameCanceled) {
+        if ((supportsMutation || supportsPersistence) && rootViewTransitionNameCanceled) {
           restoreRootViewTransitionName(finishedRoot.containerInfo);
         }
       }
diff --git a/packages/react-reconciler/src/ReactFiberConfigWithNoMutation.js b/packages/react-reconciler/src/ReactFiberConfigWithNoMutation.js
index 79cf3990a728..8768ea612e41 100644
--- a/packages/react-reconciler/src/ReactFiberConfigWithNoMutation.js
+++ b/packages/react-reconciler/src/ReactFiberConfigWithNoMutation.js
@@ -10,52 +10,153 @@
 // Renderers that don't support mutation
 // can re-export everything from this module.
 
-function shim(...args: any): empty {
-  throw new Error(
-    'The current renderer does not support mutation. ' +
-      'This error is likely caused by a bug in React. ' +
-      'Please file an issue.',
-  );
-}
-
 // Mutation (when unsupported)
 export const supportsMutation = false;
-export const cloneMutableInstance = shim;
-export const cloneMutableTextInstance = shim;
-export const appendChild = shim;
-export const appendChildToContainer = shim;
-export const commitTextUpdate = shim;
-export const commitMount = shim;
-export const commitUpdate = shim;
-export const insertBefore = shim;
-export const insertInContainerBefore = shim;
-export const removeChild = shim;
-export const removeChildFromContainer = shim;
-export const resetTextContent = shim;
-export const hideInstance = shim;
-export const hideTextInstance = shim;
-export const unhideInstance = shim;
-export const unhideTextInstance = shim;
-export const clearContainer = shim;
-export const applyViewTransitionName = shim;
-export const restoreViewTransitionName = shim;
-export const cancelViewTransitionName = shim;
-export const cancelRootViewTransitionName = shim;
-export const restoreRootViewTransitionName = shim;
-export const cloneRootViewTransitionContainer = shim;
-export const removeRootViewTransitionClone = shim;
+
+export function cloneMutableInstance(...args: any): any {
+  console.log('[shim] cloneMutableInstance');
+}
+
+export function cloneMutableTextInstance(...args: any): any {
+  console.log('[shim] cloneMutableTextInstance');
+}
+
+export function appendChild(...args: any): any {
+  console.log('[shim] appendChild');
+}
+
+export function appendChildToContainer(...args: any): any {
+  console.log('[shim] appendChildToContainer');
+}
+
+export function commitTextUpdate(...args: any): any {
+  console.log('[shim] commitTextUpdate');
+}
+
+export function commitMount(...args: any): any {
+  console.log('[shim] commitMount');
+}
+
+export function commitUpdate(...args: any): any {
+  console.log('[shim] commitUpdate');
+}
+
+export function insertBefore(...args: any): any {
+  console.log('[shim] insertBefore');
+}
+
+export function insertInContainerBefore(...args: any): any {
+  console.log('[shim] insertInContainerBefore');
+}
+
+export function removeChild(...args: any): any {
+  console.log('[shim] removeChild');
+}
+
+export function removeChildFromContainer(...args: any): any {
+  console.log('[shim] removeChildFromContainer');
+}
+
+export function resetTextContent(...args: any): any {
+  console.log('[shim] resetTextContent');
+}
+
+export function hideInstance(...args: any): any {
+  console.log('[shim] hideInstance');
+}
+
+export function hideTextInstance(...args: any): any {
+  console.log('[shim] hideTextInstance');
+}
+
+export function unhideInstance(...args: any): any {
+  console.log('[shim] unhideInstance');
+}
+
+export function unhideTextInstance(...args: any): any {
+  console.log('[shim] unhideTextInstance');
+}
+
+export function clearContainer(...args: any): any {
+  console.log('[shim] clearContainer');
+}
+
+export function applyViewTransitionName(...args: any): any {
+  console.log('[shim] applyViewTransitionName');
+}
+
+export function restoreViewTransitionName(...args: any): any {
+  console.log('[shim] restoreViewTransitionName');
+}
+
+export function cancelViewTransitionName(...args: any): any {
+  console.log('[shim] cancelViewTransitionName');
+}
+
+export function cancelRootViewTransitionName(...args: any): any {
+  console.log('[shim] cancelRootViewTransitionName');
+}
+
+export function restoreRootViewTransitionName(...args: any): any {
+  console.log('[shim] restoreRootViewTransitionName');
+}
+
+export function cloneRootViewTransitionContainer(...args: any): any {
+  console.log('[shim] cloneRootViewTransitionContainer');
+}
+
+export function removeRootViewTransitionClone(...args: any): any {
+  console.log('[shim] removeRootViewTransitionClone');
+}
+
 export type InstanceMeasurement = null;
-export const measureInstance = shim;
-export const measureClonedInstance = shim;
-export const wasInstanceInViewport = shim;
-export const hasInstanceChanged = shim;
-export const hasInstanceAffectedParent = shim;
-export const startViewTransition = shim;
+
+export function measureInstance(...args: any): any {
+  console.log('[shim] measureInstance');
+}
+
+export function measureClonedInstance(...args: any): any {
+  console.log('[shim] measureClonedInstance');
+}
+
+export function wasInstanceInViewport(...args: any): any {
+  console.log('[shim] wasInstanceInViewport');
+}
+
+export function hasInstanceChanged(...args: any): any {
+  console.log('[shim] hasInstanceChanged');
+}
+
+export function hasInstanceAffectedParent(...args: any): any {
+  console.log('[shim] hasInstanceAffectedParent');
+}
+
+export function startViewTransition(...args: any): any {
+  console.log('[shim] startViewTransition');
+}
+
 export type RunningViewTransition = null;
-export const startGestureTransition = shim;
-export const stopViewTransition = shim;
-export const addViewTransitionFinishedListener = shim;
+
+export function startGestureTransition(...args: any): any {
+  console.log('[shim] startGestureTransition');
+}
+
+export function stopViewTransition(...args: any): any {
+  console.log('[shim] stopViewTransition');
+}
+
+export function addViewTransitionFinishedListener(...args: any): any {
+  console.log('[shim] addViewTransitionFinishedListener');
+}
+
 export type ViewTransitionInstance = null | {name: string, ...};
-export const createViewTransitionInstance = shim;
+
+export function createViewTransitionInstance(...args: any): any {
+  console.log('[shim] createViewTransitionInstance');
+}
+
 export type GestureTimeline = any;
-export const getCurrentGestureOffset = shim;
+
+export function getCurrentGestureOffset(...args: any): any {
+  console.log('[shim] getCurrentGestureOffset');
+}
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fb.js
index eeabe40d33bb..6e57ad63b801 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb.js
@@ -70,7 +70,7 @@ export const syncLaneExpirationMs = 250;
 export const transitionLaneExpirationMs = 5000;
 export const enableYieldingBeforePassive: boolean = false;
 export const enableThrottledScheduling: boolean = false;
-export const enableViewTransition: boolean = false;
+export const enableViewTransition: boolean = true;
 export const enableGestureTransition: boolean = false;
 export const enableScrollEndPolyfill: boolean = true;
 export const enableSuspenseyImages: boolean = false;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
index a2e623ff5201..268b53cf90bd 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
@@ -56,7 +56,7 @@ export const syncLaneExpirationMs = 250;
 export const transitionLaneExpirationMs = 5000;
 export const enableYieldingBeforePassive = false;
 export const enableThrottledScheduling = false;
-export const enableViewTransition = false;
+export const enableViewTransition = true;
 export const enableGestureTransition = false;
 export const enableScrollEndPolyfill = true;
 export const enableSuspenseyImages = false;

From 02754699bea1ba7dcf0bfc2a09088fc040163f90 Mon Sep 17 00:00:00 2001
From: Zeya Peng <zeyap@meta.com>
Date: Fri, 6 Feb 2026 16:07:31 -0500
Subject: [PATCH 2/8] invoke FabricUIManager methods

---
 .../src/ReactFiberConfigFabric.js             | 20 ++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/packages/react-native-renderer/src/ReactFiberConfigFabric.js b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
index 3c293aca3738..c44984248452 100644
--- a/packages/react-native-renderer/src/ReactFiberConfigFabric.js
+++ b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
@@ -58,6 +58,10 @@ const {
   unstable_ContinuousEventPriority: FabricContinuousPriority,
   unstable_IdleEventPriority: FabricIdlePriority,
   unstable_getCurrentEventPriority: fabricGetCurrentEventPriority,
+  measureInstance: fabricMeasureInstance,
+  applyViewTransitionName: fabricApplyViewTransitionName,
+  executeViewTransition: fabricExecuteViewTransition,
+  startViewTransition: fabricStartViewTransition,
 } = nativeFabricUIManager;
 
 import {getClosestInstanceFromNode} from './ReactFabricComponentTree';
@@ -259,7 +263,18 @@ export function removeRootViewTransitionClone(
 
 export function measureInstance(instance: Instance): InstanceMeasurement {
   console.log('[shim] measureInstance ', instance.canonical.nativeTag);
-  return {rect: {x: 0, y: 0, width: 0, height: 0}, abs: false, clip: false, view: true};
+  var measurement = fabricMeasureInstance(instance.node);
+  return {
+    rect: {
+      x: measurement.x,
+      y: measurement.y,
+      width: measurement.width,
+      height: measurement.height
+    },
+    abs: false,
+    clip: false,
+    view: true
+  };
 }
 
 export function measureClonedInstance(instance: Instance): InstanceMeasurement {
@@ -337,6 +352,7 @@ export function applyViewTransitionName(
 ): void {
   // add view-transition-name to things that might animate for browser
   console.log('[shim] applyViewTransitionName', name, className, instance.canonical.nativeTag);
+  fabricApplyViewTransitionName(instance.node, name, className);
 }
 
 export function startViewTransition(
@@ -353,6 +369,7 @@ export function startViewTransition(
   finishedAnimation: () => void,
 ): RunningViewTransition {
   console.log('[shim] startViewTransition transitionTypes', JSON.stringify(transitionTypes ?? []));
+  fabricStartViewTransition();
 
   // mutation phase
   console.log('[shim] startViewTransition mutations start');
@@ -367,6 +384,7 @@ export function startViewTransition(
   // transition ready
   console.log('[shim] startViewTransition transition ready');
   spawnedWorkCallback();
+  fabricExecuteViewTransition();
 
   console.log('[shim] startViewTransition finishedAnimation');
   // finishedAnimation();

From 7d45a6f335bbcbf895fc1668ae7acc14a6301a51 Mon Sep 17 00:00:00 2001
From: Zeya Peng <zeyap@meta.com>
Date: Fri, 6 Feb 2026 17:42:16 -0500
Subject: [PATCH 3/8] Rename fabricStartViewTransition to
 fabricViewTransitionStarted

Better reflects that this signals the transition has started rather than
initiating it.
---
 .../src/ReactFiberConfigFabric.js             | 51 ++++++++++---------
 1 file changed, 27 insertions(+), 24 deletions(-)

diff --git a/packages/react-native-renderer/src/ReactFiberConfigFabric.js b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
index c44984248452..52b4f1216554 100644
--- a/packages/react-native-renderer/src/ReactFiberConfigFabric.js
+++ b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
@@ -60,7 +60,6 @@ const {
   unstable_getCurrentEventPriority: fabricGetCurrentEventPriority,
   measureInstance: fabricMeasureInstance,
   applyViewTransitionName: fabricApplyViewTransitionName,
-  executeViewTransition: fabricExecuteViewTransition,
   startViewTransition: fabricStartViewTransition,
 } = nativeFabricUIManager;
 
@@ -368,30 +367,33 @@ export function startViewTransition(
   blockedCallback: (name: string) => void,
   finishedAnimation: () => void,
 ): RunningViewTransition {
-  console.log('[shim] startViewTransition transitionTypes', JSON.stringify(transitionTypes ?? []));
-  fabricStartViewTransition();
-
-  // mutation phase
-  console.log('[shim] startViewTransition mutations start');
-  mutationCallback();
-  layoutCallback(); // run layout effects
-  afterMutationCallback();
-  console.log('[shim] startViewTransition mutations finish');
-
-  // browser creates pseudo elements
-  console.log('[shim] startViewTransition pseudo element captured');
-
-  // transition ready
-  console.log('[shim] startViewTransition transition ready');
-  spawnedWorkCallback();
-  fabricExecuteViewTransition();
-
-  console.log('[shim] startViewTransition finishedAnimation');
-  // finishedAnimation();
+  console.log(
+    "[shim] startViewTransition transitionTypes",
+    JSON.stringify(null != transitionTypes ? transitionTypes : [])
+  );
 
-  // transition ends
-  console.log('[shim] startViewTransition transition ends');
-  passiveCallback();
+  fabricStartViewTransition(
+    // mutation
+    ()=>{
+      console.log("[shim] startViewTransition mutations start");
+      // completeRoot should run here
+    mutationCallback();
+    layoutCallback();
+    afterMutationCallback();
+    console.log("[shim] startViewTransition mutations finish");
+  },
+  // onReady
+    ()=>{
+      console.log("[shim] startViewTransition pseudo element captured");
+  console.log("[shim] startViewTransition transition ready");
+    spawnedWorkCallback();
+  },
+  // onComplete
+  ()=>{
+    console.log("[shim] startViewTransition finishedAnimation");
+    console.log("[shim] startViewTransition transition ends");
+    passiveCallback();
+  });
 
   return null;
 }
@@ -789,6 +791,7 @@ export function replaceContainerChildren(
   container: Container,
   newChildren: ChildSet,
 ): void {
+  console.log('completeRoot');
   completeRoot(container.containerTag, newChildren);
 }
 

From a8e8bccc891dcaf726115a450c84fef5277925bd Mon Sep 17 00:00:00 2001
From: Zeya Peng <zeyap@meta.com>
Date: Wed, 11 Feb 2026 11:59:03 -0500
Subject: [PATCH 4/8] restore/cancelViewTransitionName; fallback behavior if
 fabric doesnt enable startViewTransition

---
 .../src/ReactFiberConfigFabric.js             |  77 ++++----
 .../src/ReactFiberConfigWithNoMutation.js     | 187 ++++--------------
 2 files changed, 78 insertions(+), 186 deletions(-)

diff --git a/packages/react-native-renderer/src/ReactFiberConfigFabric.js b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
index 52b4f1216554..b1e35698cb5c 100644
--- a/packages/react-native-renderer/src/ReactFiberConfigFabric.js
+++ b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
@@ -61,6 +61,8 @@ const {
   measureInstance: fabricMeasureInstance,
   applyViewTransitionName: fabricApplyViewTransitionName,
   startViewTransition: fabricStartViewTransition,
+  restoreViewTransitionName: fabricRestoreViewTransitionName,
+  cancelViewTransitionName: fabricCancelViewTransitionName,
 } = nativeFabricUIManager;
 
 import {getClosestInstanceFromNode} from './ReactFabricComponentTree';
@@ -76,12 +78,6 @@ import {passChildrenWhenCloningPersistedNodes} from 'shared/ReactFeatureFlags';
 import {REACT_CONTEXT_TYPE} from 'shared/ReactSymbols';
 import type {ReactContext} from 'shared/ReactTypes';
 
-export * from 'react-reconciler/src/ReactFiberConfigWithNoHydration';
-export * from 'react-reconciler/src/ReactFiberConfigWithNoScopes';
-export * from 'react-reconciler/src/ReactFiberConfigWithNoTestSelectors';
-export * from 'react-reconciler/src/ReactFiberConfigWithNoResources';
-export * from 'react-reconciler/src/ReactFiberConfigWithNoSingletons';
-
 export {default as rendererVersion} from 'shared/ReactVersion'; // TODO: Consider exporting the react-native version.
 export const rendererPackageName = 'react-native-renderer';
 export const extraDevToolsConfig = {
@@ -167,8 +163,14 @@ if (registerEventHandler) {
   registerEventHandler(dispatchEvent);
 }
 
+export * from 'react-reconciler/src/ReactFiberConfigWithNoHydration';
+export * from 'react-reconciler/src/ReactFiberConfigWithNoScopes';
+export * from 'react-reconciler/src/ReactFiberConfigWithNoTestSelectors';
+export * from 'react-reconciler/src/ReactFiberConfigWithNoResources';
+export * from 'react-reconciler/src/ReactFiberConfigWithNoSingletons';
+
 // -------------------
-//     Mutation
+//    ViewTransition
 // -------------------
 
 function shim(...args: any): empty {
@@ -192,9 +194,7 @@ export function commitMount(
   type: string,
   newProps: Props,
   internalInstanceHandle: Object,
-): void {
-  console.log('[shim] commitMount');
-}
+): void {}
 
 export const commitUpdate = shim;
 export const insertBefore = shim;
@@ -228,41 +228,41 @@ export function restoreViewTransitionName(
   instance: Instance,
   props: Props,
 ): void {
-  console.log('[shim] restoreViewTransitionName ', instance.canonical.nativeTag);
+  fabricRestoreViewTransitionName(instance.node);
 }
 
+// Cancel the old and new snapshots of viewTransitionName
 export function cancelViewTransitionName(
   instance: Instance,
   oldName: string,
   props: Props,
 ): void {
-  console.log('[shim] cancelViewTransitionName ', oldName, instance.canonical.nativeTag);
+  fabricCancelViewTransitionName(instance.node, oldName);
 }
 
 export function cancelRootViewTransitionName(rootContainer: Container): void {
-  console.log('[shim] cancelRootViewTransitionName');
+
 }
 
 export function restoreRootViewTransitionName(rootContainer: Container): void {
-  console.log('[shim] restoreRootViewTransitionName');
+
 }
 
 export function cloneRootViewTransitionContainer(
   rootContainer: Container,
 ): Instance {
-  console.log('[shim] cloneRootViewTransitionContainer');
 }
 
 export function removeRootViewTransitionClone(
   rootContainer: Container,
   clone: Instance,
 ): void {
-  console.log('[shim] removeRootViewTransitionClone');
+
 }
 
 export function measureInstance(instance: Instance): InstanceMeasurement {
-  console.log('[shim] measureInstance ', instance.canonical.nativeTag);
-  var measurement = fabricMeasureInstance(instance.node);
+
+  const measurement = fabricMeasureInstance(instance.node);
   return {
     rect: {
       x: measurement.x,
@@ -277,14 +277,12 @@ export function measureInstance(instance: Instance): InstanceMeasurement {
 }
 
 export function measureClonedInstance(instance: Instance): InstanceMeasurement {
-  console.log('[shim] measureClonedInstance ', instance.canonical.nativeTag);
   return {rect: {x: 0, y: 0, width: 0, height: 0}, abs: false, clip: false, view: true};
 }
 
 export function wasInstanceInViewport(
   measurement: InstanceMeasurement,
 ): boolean {
-  console.log('[shim] wasInstanceInViewport');
   return measurement.view;
 }
 
@@ -292,7 +290,6 @@ export function hasInstanceChanged(
   oldMeasurement: InstanceMeasurement,
   newMeasurement: InstanceMeasurement,
 ): boolean {
-  console.log('[shim] hasInstanceChanged');
   return false;
 }
 
@@ -300,7 +297,6 @@ export function hasInstanceAffectedParent(
   oldMeasurement: InstanceMeasurement,
   newMeasurement: InstanceMeasurement,
 ): boolean {
-  console.log('[shim] hasInstanceAffectedParent');
   return false;
 }
 
@@ -316,31 +312,26 @@ export function startGestureTransition(
   errorCallback: (error: mixed) => void,
   finishedAnimation: () => void,
 ): RunningViewTransition {
-  console.log('[shim] startGestureTransition');
   return null;
 }
 
 export function stopViewTransition(transition: RunningViewTransition): void {
-  console.log('[shim] stopViewTransition');
 }
 
 export function addViewTransitionFinishedListener(
   transition: RunningViewTransition,
   callback: () => void,
 ): void {
-  console.log('[shim] addViewTransitionFinishedListener');
   callback();
 }
 
 export function createViewTransitionInstance(
   name: string,
 ): ViewTransitionInstance {
-  console.log('[shim] createViewTransitionInstance', name);
   return {name};
 }
 
 export function getCurrentGestureOffset(timeline: GestureTimeline): number {
-  console.log('[shim] getCurrentGestureOffset');
   return 0;
 }
 
@@ -350,7 +341,6 @@ export function applyViewTransitionName(
   className: ?string,
 ): void {
   // add view-transition-name to things that might animate for browser
-  console.log('[shim] applyViewTransitionName', name, className, instance.canonical.nativeTag);
   fabricApplyViewTransitionName(instance.node, name, className);
 }
 
@@ -367,34 +357,38 @@ export function startViewTransition(
   blockedCallback: (name: string) => void,
   finishedAnimation: () => void,
 ): RunningViewTransition {
-  console.log(
-    "[shim] startViewTransition transitionTypes",
-    JSON.stringify(null != transitionTypes ? transitionTypes : [])
-  );
 
-  fabricStartViewTransition(
+  const startedTransition = fabricStartViewTransition(
     // mutation
     ()=>{
-      console.log("[shim] startViewTransition mutations start");
-      // completeRoot should run here
-    mutationCallback();
+    mutationCallback(); // completeRoot should run here
     layoutCallback();
     afterMutationCallback();
-    console.log("[shim] startViewTransition mutations finish");
   },
   // onReady
     ()=>{
-      console.log("[shim] startViewTransition pseudo element captured");
-  console.log("[shim] startViewTransition transition ready");
     spawnedWorkCallback();
   },
   // onComplete
   ()=>{
-    console.log("[shim] startViewTransition finishedAnimation");
-    console.log("[shim] startViewTransition transition ends");
     passiveCallback();
   });
 
+  if (!startedTransition) {
+    if (__DEV__) {
+      console.warn(
+        "startViewTransition didn't kick off transition in Fabric, the ViewTransition ReactNativeFeatureFlag might not be enabled.",
+      );
+    }
+     // Flush remaining work synchronously.
+    mutationCallback();
+    layoutCallback();
+    // Skip afterMutationCallback(). We don't need it since we're not animating.
+    spawnedWorkCallback();
+    // Skip passiveCallback(). Spawned work will schedule a task.
+    return null;
+  }
+
   return null;
 }
 
@@ -791,7 +785,6 @@ export function replaceContainerChildren(
   container: Container,
   newChildren: ChildSet,
 ): void {
-  console.log('completeRoot');
   completeRoot(container.containerTag, newChildren);
 }
 
diff --git a/packages/react-reconciler/src/ReactFiberConfigWithNoMutation.js b/packages/react-reconciler/src/ReactFiberConfigWithNoMutation.js
index 8768ea612e41..79cf3990a728 100644
--- a/packages/react-reconciler/src/ReactFiberConfigWithNoMutation.js
+++ b/packages/react-reconciler/src/ReactFiberConfigWithNoMutation.js
@@ -10,153 +10,52 @@
 // Renderers that don't support mutation
 // can re-export everything from this module.
 
-// Mutation (when unsupported)
-export const supportsMutation = false;
-
-export function cloneMutableInstance(...args: any): any {
-  console.log('[shim] cloneMutableInstance');
-}
-
-export function cloneMutableTextInstance(...args: any): any {
-  console.log('[shim] cloneMutableTextInstance');
-}
-
-export function appendChild(...args: any): any {
-  console.log('[shim] appendChild');
-}
-
-export function appendChildToContainer(...args: any): any {
-  console.log('[shim] appendChildToContainer');
-}
-
-export function commitTextUpdate(...args: any): any {
-  console.log('[shim] commitTextUpdate');
-}
-
-export function commitMount(...args: any): any {
-  console.log('[shim] commitMount');
-}
-
-export function commitUpdate(...args: any): any {
-  console.log('[shim] commitUpdate');
-}
-
-export function insertBefore(...args: any): any {
-  console.log('[shim] insertBefore');
-}
-
-export function insertInContainerBefore(...args: any): any {
-  console.log('[shim] insertInContainerBefore');
-}
-
-export function removeChild(...args: any): any {
-  console.log('[shim] removeChild');
-}
-
-export function removeChildFromContainer(...args: any): any {
-  console.log('[shim] removeChildFromContainer');
-}
-
-export function resetTextContent(...args: any): any {
-  console.log('[shim] resetTextContent');
-}
-
-export function hideInstance(...args: any): any {
-  console.log('[shim] hideInstance');
-}
-
-export function hideTextInstance(...args: any): any {
-  console.log('[shim] hideTextInstance');
-}
-
-export function unhideInstance(...args: any): any {
-  console.log('[shim] unhideInstance');
-}
-
-export function unhideTextInstance(...args: any): any {
-  console.log('[shim] unhideTextInstance');
-}
-
-export function clearContainer(...args: any): any {
-  console.log('[shim] clearContainer');
-}
-
-export function applyViewTransitionName(...args: any): any {
-  console.log('[shim] applyViewTransitionName');
-}
-
-export function restoreViewTransitionName(...args: any): any {
-  console.log('[shim] restoreViewTransitionName');
-}
-
-export function cancelViewTransitionName(...args: any): any {
-  console.log('[shim] cancelViewTransitionName');
-}
-
-export function cancelRootViewTransitionName(...args: any): any {
-  console.log('[shim] cancelRootViewTransitionName');
-}
-
-export function restoreRootViewTransitionName(...args: any): any {
-  console.log('[shim] restoreRootViewTransitionName');
-}
-
-export function cloneRootViewTransitionContainer(...args: any): any {
-  console.log('[shim] cloneRootViewTransitionContainer');
-}
-
-export function removeRootViewTransitionClone(...args: any): any {
-  console.log('[shim] removeRootViewTransitionClone');
+function shim(...args: any): empty {
+  throw new Error(
+    'The current renderer does not support mutation. ' +
+      'This error is likely caused by a bug in React. ' +
+      'Please file an issue.',
+  );
 }
 
+// Mutation (when unsupported)
+export const supportsMutation = false;
+export const cloneMutableInstance = shim;
+export const cloneMutableTextInstance = shim;
+export const appendChild = shim;
+export const appendChildToContainer = shim;
+export const commitTextUpdate = shim;
+export const commitMount = shim;
+export const commitUpdate = shim;
+export const insertBefore = shim;
+export const insertInContainerBefore = shim;
+export const removeChild = shim;
+export const removeChildFromContainer = shim;
+export const resetTextContent = shim;
+export const hideInstance = shim;
+export const hideTextInstance = shim;
+export const unhideInstance = shim;
+export const unhideTextInstance = shim;
+export const clearContainer = shim;
+export const applyViewTransitionName = shim;
+export const restoreViewTransitionName = shim;
+export const cancelViewTransitionName = shim;
+export const cancelRootViewTransitionName = shim;
+export const restoreRootViewTransitionName = shim;
+export const cloneRootViewTransitionContainer = shim;
+export const removeRootViewTransitionClone = shim;
 export type InstanceMeasurement = null;
-
-export function measureInstance(...args: any): any {
-  console.log('[shim] measureInstance');
-}
-
-export function measureClonedInstance(...args: any): any {
-  console.log('[shim] measureClonedInstance');
-}
-
-export function wasInstanceInViewport(...args: any): any {
-  console.log('[shim] wasInstanceInViewport');
-}
-
-export function hasInstanceChanged(...args: any): any {
-  console.log('[shim] hasInstanceChanged');
-}
-
-export function hasInstanceAffectedParent(...args: any): any {
-  console.log('[shim] hasInstanceAffectedParent');
-}
-
-export function startViewTransition(...args: any): any {
-  console.log('[shim] startViewTransition');
-}
-
+export const measureInstance = shim;
+export const measureClonedInstance = shim;
+export const wasInstanceInViewport = shim;
+export const hasInstanceChanged = shim;
+export const hasInstanceAffectedParent = shim;
+export const startViewTransition = shim;
 export type RunningViewTransition = null;
-
-export function startGestureTransition(...args: any): any {
-  console.log('[shim] startGestureTransition');
-}
-
-export function stopViewTransition(...args: any): any {
-  console.log('[shim] stopViewTransition');
-}
-
-export function addViewTransitionFinishedListener(...args: any): any {
-  console.log('[shim] addViewTransitionFinishedListener');
-}
-
+export const startGestureTransition = shim;
+export const stopViewTransition = shim;
+export const addViewTransitionFinishedListener = shim;
 export type ViewTransitionInstance = null | {name: string, ...};
-
-export function createViewTransitionInstance(...args: any): any {
-  console.log('[shim] createViewTransitionInstance');
-}
-
+export const createViewTransitionInstance = shim;
 export type GestureTimeline = any;
-
-export function getCurrentGestureOffset(...args: any): any {
-  console.log('[shim] getCurrentGestureOffset');
-}
+export const getCurrentGestureOffset = shim;

From 15734d064c6cee125c96805c25789db6a64bdbe1 Mon Sep 17 00:00:00 2001
From: Zeya Peng <zeyap@meta.com>
Date: Wed, 11 Feb 2026 12:06:37 -0500
Subject: [PATCH 5/8] fix flow

---
 .../src/ReactFiberConfigFabric.js             | 35 +++++++++++++++++--
 scripts/flow/react-native-host-hooks.js       | 18 ++++++++++
 2 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/packages/react-native-renderer/src/ReactFiberConfigFabric.js b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
index b1e35698cb5c..8162ed80fa7c 100644
--- a/packages/react-native-renderer/src/ReactFiberConfigFabric.js
+++ b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
@@ -241,23 +241,34 @@ export function cancelViewTransitionName(
 }
 
 export function cancelRootViewTransitionName(rootContainer: Container): void {
-
+  if (__DEV__) {
+    console.warn('cancelRootViewTransitionName is not implemented');
+  }
 }
 
 export function restoreRootViewTransitionName(rootContainer: Container): void {
-
+  if (__DEV__) {
+    console.warn('restoreRootViewTransitionName is not implemented');
+  }
 }
 
 export function cloneRootViewTransitionContainer(
   rootContainer: Container,
 ): Instance {
+  if (__DEV__) {
+    console.warn('cloneRootViewTransitionContainer is not implemented');
+  }
+  // $FlowFixMe[incompatible-return] Return empty stub
+  return null;
 }
 
 export function removeRootViewTransitionClone(
   rootContainer: Container,
   clone: Instance,
 ): void {
-
+  if (__DEV__) {
+    console.warn('removeRootViewTransitionClone is not implemented');
+  }
 }
 
 export function measureInstance(instance: Instance): InstanceMeasurement {
@@ -277,6 +288,9 @@ export function measureInstance(instance: Instance): InstanceMeasurement {
 }
 
 export function measureClonedInstance(instance: Instance): InstanceMeasurement {
+  if (__DEV__) {
+    console.warn('measureClonedInstance is not implemented');
+  }
   return {rect: {x: 0, y: 0, width: 0, height: 0}, abs: false, clip: false, view: true};
 }
 
@@ -290,6 +304,9 @@ export function hasInstanceChanged(
   oldMeasurement: InstanceMeasurement,
   newMeasurement: InstanceMeasurement,
 ): boolean {
+  if (__DEV__) {
+    console.warn('hasInstanceChanged is not implemented');
+  }
   return false;
 }
 
@@ -297,6 +314,9 @@ export function hasInstanceAffectedParent(
   oldMeasurement: InstanceMeasurement,
   newMeasurement: InstanceMeasurement,
 ): boolean {
+  if (__DEV__) {
+    console.warn('hasInstanceAffectedParent is not implemented');
+  }
   return false;
 }
 
@@ -312,10 +332,16 @@ export function startGestureTransition(
   errorCallback: (error: mixed) => void,
   finishedAnimation: () => void,
 ): RunningViewTransition {
+  if (__DEV__) {
+    console.warn('startGestureTransition is not implemented');
+  }
   return null;
 }
 
 export function stopViewTransition(transition: RunningViewTransition): void {
+  if (__DEV__) {
+    console.warn('stopViewTransition is not implemented');
+  }
 }
 
 export function addViewTransitionFinishedListener(
@@ -332,6 +358,9 @@ export function createViewTransitionInstance(
 }
 
 export function getCurrentGestureOffset(timeline: GestureTimeline): number {
+  if (__DEV__) {
+    console.warn('getCurrentGestureOffset is not implemented');
+  }
   return 0;
 }
 
diff --git a/scripts/flow/react-native-host-hooks.js b/scripts/flow/react-native-host-hooks.js
index 227c78bca24a..db8bbd9efaee 100644
--- a/scripts/flow/react-native-host-hooks.js
+++ b/scripts/flow/react-native-host-hooks.js
@@ -301,5 +301,23 @@ declare const nativeFabricUIManager: {
   unstable_ContinuousEventPriority: number,
   unstable_IdleEventPriority: number,
   unstable_getCurrentEventPriority: () => number,
+  measureInstance: (node: Object) => {
+    x: number,
+    y: number,
+    width: number,
+    height: number,
+  },
+  applyViewTransitionName: (
+    node: Object,
+    name: string,
+    className: ?string,
+  ) => void,
+  startViewTransition: (
+    mutationCallback: () => void,
+    onReady: () => void,
+    onComplete: () => void,
+  ) => boolean,
+  restoreViewTransitionName: (node: Object) => void,
+  cancelViewTransitionName: (node: Object, oldName: string) => void,
   ...
 };

From d6e22c790c9ed0bfc77aba1397e5b57bf0557d0f Mon Sep 17 00:00:00 2001
From: Zeya Peng <zeyap@meta.com>
Date: Wed, 11 Feb 2026 12:14:35 -0500
Subject: [PATCH 6/8] turn off enableViewTransition for fb rn renderer by
 default

---
 packages/shared/forks/ReactFeatureFlags.native-fb.js            | 2 +-
 .../shared/forks/ReactFeatureFlags.test-renderer.native-fb.js   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fb.js
index 6e57ad63b801..eeabe40d33bb 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb.js
@@ -70,7 +70,7 @@ export const syncLaneExpirationMs = 250;
 export const transitionLaneExpirationMs = 5000;
 export const enableYieldingBeforePassive: boolean = false;
 export const enableThrottledScheduling: boolean = false;
-export const enableViewTransition: boolean = true;
+export const enableViewTransition: boolean = false;
 export const enableGestureTransition: boolean = false;
 export const enableScrollEndPolyfill: boolean = true;
 export const enableSuspenseyImages: boolean = false;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
index 268b53cf90bd..a2e623ff5201 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
@@ -56,7 +56,7 @@ export const syncLaneExpirationMs = 250;
 export const transitionLaneExpirationMs = 5000;
 export const enableYieldingBeforePassive = false;
 export const enableThrottledScheduling = false;
-export const enableViewTransition = true;
+export const enableViewTransition = false;
 export const enableGestureTransition = false;
 export const enableScrollEndPolyfill = true;
 export const enableSuspenseyImages = false;

From c1d82d87bedd9d9a96acb44b32fcf499de2eb1b8 Mon Sep 17 00:00:00 2001
From: Zeya Peng <zeyap@meta.com>
Date: Wed, 11 Feb 2026 12:21:29 -0500
Subject: [PATCH 7/8] prettier

---
 .../src/ReactFiberConfigFabric.js             | 42 ++++++++++---------
 .../src/ReactFiberCommitWork.js               |  5 ++-
 2 files changed, 27 insertions(+), 20 deletions(-)

diff --git a/packages/react-native-renderer/src/ReactFiberConfigFabric.js b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
index 8162ed80fa7c..e9ecb5bf3321 100644
--- a/packages/react-native-renderer/src/ReactFiberConfigFabric.js
+++ b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
@@ -272,18 +272,17 @@ export function removeRootViewTransitionClone(
 }
 
 export function measureInstance(instance: Instance): InstanceMeasurement {
-
   const measurement = fabricMeasureInstance(instance.node);
   return {
     rect: {
       x: measurement.x,
       y: measurement.y,
       width: measurement.width,
-      height: measurement.height
+      height: measurement.height,
     },
     abs: false,
     clip: false,
-    view: true
+    view: true,
   };
 }
 
@@ -291,7 +290,12 @@ export function measureClonedInstance(instance: Instance): InstanceMeasurement {
   if (__DEV__) {
     console.warn('measureClonedInstance is not implemented');
   }
-  return {rect: {x: 0, y: 0, width: 0, height: 0}, abs: false, clip: false, view: true};
+  return {
+    rect: {x: 0, y: 0, width: 0, height: 0},
+    abs: false,
+    clip: false,
+    view: true,
+  };
 }
 
 export function wasInstanceInViewport(
@@ -386,22 +390,22 @@ export function startViewTransition(
   blockedCallback: (name: string) => void,
   finishedAnimation: () => void,
 ): RunningViewTransition {
-
   const startedTransition = fabricStartViewTransition(
     // mutation
-    ()=>{
-    mutationCallback(); // completeRoot should run here
-    layoutCallback();
-    afterMutationCallback();
-  },
-  // onReady
-    ()=>{
-    spawnedWorkCallback();
-  },
-  // onComplete
-  ()=>{
-    passiveCallback();
-  });
+    () => {
+      mutationCallback(); // completeRoot should run here
+      layoutCallback();
+      afterMutationCallback();
+    },
+    // onReady
+    () => {
+      spawnedWorkCallback();
+    },
+    // onComplete
+    () => {
+      passiveCallback();
+    },
+  );
 
   if (!startedTransition) {
     if (__DEV__) {
@@ -409,7 +413,7 @@ export function startViewTransition(
         "startViewTransition didn't kick off transition in Fabric, the ViewTransition ReactNativeFeatureFlag might not be enabled.",
       );
     }
-     // Flush remaining work synchronously.
+    // Flush remaining work synchronously.
     mutationCallback();
     layoutCallback();
     // Skip afterMutationCallback(). We don't need it since we're not animating.
diff --git a/packages/react-reconciler/src/ReactFiberCommitWork.js b/packages/react-reconciler/src/ReactFiberCommitWork.js
index 4b4531c863e1..250b23f97057 100644
--- a/packages/react-reconciler/src/ReactFiberCommitWork.js
+++ b/packages/react-reconciler/src/ReactFiberCommitWork.js
@@ -3709,7 +3709,10 @@ function commitPassiveMountOnFiber(
       }
 
       if (isViewTransitionEligible) {
-        if ((supportsMutation || supportsPersistence) && rootViewTransitionNameCanceled) {
+        if (
+          (supportsMutation || supportsPersistence) &&
+          rootViewTransitionNameCanceled
+        ) {
           restoreRootViewTransitionName(finishedRoot.containerInfo);
         }
       }

From 86487822aea776b455ac9e6bf199096ea2772b63 Mon Sep 17 00:00:00 2001
From: Zeya Peng <zeyap@meta.com>
Date: Fri, 13 Feb 2026 12:32:19 -0500
Subject: [PATCH 8/8] make startViewTransition async and return ready &
 finished promises

---
 .../src/ReactFiberConfigFabric.js                 | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/packages/react-native-renderer/src/ReactFiberConfigFabric.js b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
index e9ecb5bf3321..c503d8820bcb 100644
--- a/packages/react-native-renderer/src/ReactFiberConfigFabric.js
+++ b/packages/react-native-renderer/src/ReactFiberConfigFabric.js
@@ -215,7 +215,12 @@ export type InstanceMeasurement = {
   view: boolean,
 };
 
-export type RunningViewTransition = null;
+export type RunningViewTransition = {
+  skipTransition(): void,
+  finished: Promise<void>,
+  ready: Promise<void>,
+  ...
+};
 
 export type ViewTransitionInstance = null | {
   name: string,
@@ -389,8 +394,8 @@ export function startViewTransition(
   errorCallback: (error: mixed) => void,
   blockedCallback: (name: string) => void,
   finishedAnimation: () => void,
-): RunningViewTransition {
-  const startedTransition = fabricStartViewTransition(
+): null | RunningViewTransition {
+  const transition = fabricStartViewTransition(
     // mutation
     () => {
       mutationCallback(); // completeRoot should run here
@@ -407,7 +412,7 @@ export function startViewTransition(
     },
   );
 
-  if (!startedTransition) {
+  if (transition == null) {
     if (__DEV__) {
       console.warn(
         "startViewTransition didn't kick off transition in Fabric, the ViewTransition ReactNativeFeatureFlag might not be enabled.",
@@ -422,7 +427,7 @@ export function startViewTransition(
     return null;
   }
 
-  return null;
+  return transition;
 }
 
 export function appendInitialChild(