Enable ViewTransition onUpdate for persistence mode (Fabric)#36363
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zeyap wants to merge 1 commit intofacebook:mainfrom
Open
Enable ViewTransition onUpdate for persistence mode (Fabric)#36363zeyap wants to merge 1 commit intofacebook:mainfrom
zeyap wants to merge 1 commit intofacebook:mainfrom
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In persistence mode (React Native Fabric), host component updates are performed as clones during the render phase (completeWork) rather than as mutations during commit. This caused two issues preventing ViewTransition's onUpdate callback from firing: 1. The Cloned flag was not included in BeforeAndAfterMutationTransitionMask, so the before-mutation traversal never descended into subtrees with persistence-mode clones. This meant shouldStartViewTransition was never set, startViewTransition was never called, and flushAfterMutationEffects never ran. 2. trackHostMutation() was never called for persistence-mode clones, so viewTransitionMutationContext stayed false and the Update flag was never set on ViewTransition fibers during commit. This adds Cloned to BeforeAndAfterMutationTransitionMask (gated behind enableViewTransitionForPersistenceMode) and introduces commitHostCloned() in ReactFiberCommitHostEffects to track persistence-mode mutations for ViewTransition detection.
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Summary
ClonedtoBeforeAndAfterMutationTransitionMask(gated behindenableViewTransitionForPersistenceMode) so the before-mutation phase traverses into subtrees where persistence-mode clones occurred, allowingshouldStartViewTransitionto be set andflushAfterMutationEffectsto runcommitHostCloned()inReactFiberCommitHostEffectsto calltrackHostMutation()for persistence-mode clones, soviewTransitionMutationContextis set and theUpdateflag gets applied to parentViewTransitionfibers during commitRoot Cause
In persistence mode (Fabric), host component updates happen via
cloneInstanceduring the render phase (completeWork), not viacommitUpdateduring commit. The view transition system relied on two mutation-mode-only mechanisms:BeforeAndAfterMutationTransitionMaskdidn't includeCloned, so the before-mutation traversal skipped subtrees with only persistence-mode changes —startViewTransitionwas never called andflushAfterMutationEffectsnever rantrackHostMutation()was only called from mutation-mode commit paths (commitHostUpdate,commitHostTextUpdate), soviewTransitionMutationContextstayedfalseand theUpdateflag was never set onViewTransitionfibersTest plan
onUpdatefires onViewTransitioncomponents in React Native Fabric when child host components updateenableViewTransitionForPersistenceModeandsupportsPersistence)