Fixed Children composable sometimes sticks with switching the stack quickly

[arkivanov]

Fixes: #862
Related to: #976

Summary by CodeRabbit

• Bug Fixes
  • Enhanced stack animation behavior during component state transitions for improved reliability.
  • Improved animation completion callback handling to ensure consistent animation performance across recompositions.

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[coderabbitai]

📝 Walkthrough

Walkthrough

Two targeted fixes to the stack animation system address rapid navigation freezing. One change adds conditional logic for single-item stack updates to preserve non-exiting items, while the other wraps callback references with rememberUpdatedState to maintain freshness across recompositions.

Changes

Cohort / File(s)	Summary
Stack Animation State Management extensions-compose/src/commonMain/kotlin/com/arkivanov/decompose/extensions/compose/stack/animation/AbstractStackAnimation.kt, extensions-compose/src/commonMain/kotlin/com/arkivanov/decompose/extensions/compose/stack/animation/DefaultStackAnimator.kt	Fixed animation handling during rapid updates: (1) AbstractStackAnimation now conditionally preserves single non-exiting items instead of wholesale replacement, comparing last keys of old/new sets. (2) DefaultStackAnimator wraps onFinished callback with rememberUpdatedState to ensure callback freshness across recompositions. Both changes prevent animation state corruption during rapid navigation.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• Don't animate the previous child after predictive back gesture finished and stack popped #774: Implements similar guarded replacement logic for single-item stack cases in animation updates.
• Cancel predictive back gesture when stack changed (experimental animation API) #806: Contains analogous animation update changes for experimental vs. non-experimental DefaultStackAnimation/Animator implementations.
• Fixed stack animation not updating to new child component instance when active configuration is unchanged #794: Modifies stack animation item-update logic in AbstractStackAnimation to preserve items when active keys/instances don't change.

Poem

🐰 Hop, hop, the tabs now dance with grace,
No more freezing in this animation race,
State remembered, callbacks fresh and true,
Rapid navigation flows right through! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the fix for the animation/rendering issue that occurs when rapidly switching stacks, which is the primary objective of this changeset.
Linked Issues check	✅ Passed	The code changes address the core issue [#862] by fixing the stack animation logic to properly handle rapid switching, preventing the navigation from freezing.
Out of Scope Changes check	✅ Passed	All changes are focused on stack animation handling in the compose extensions and are directly related to resolving the rapid tab switching freeze issue.

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✨ Finishing touches

• 📝 Generate docstrings

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