Allow anyState transitions to interrupt crossFade & fix transition bugs

[GuoLei1990]

Further optimizations and fixes based on #2885, which had redundant code, could be more concise, and missed a bug in updateTransitionsIndex.

Note: This PR is built upon the work of @luzhuang in #2885. Thanks for the initial implementation!
Co-Authored-By: luzhuang <luzhuang@aspect3d.com>

Summary

From #2885 (re-implemented with cleaner code)

• Allow anyState noExitTime transitions to interrupt crossFade: During CrossFading or FixedCrossFading, anyState noExitTime transitions can interrupt the current crossFade and redirect to a new state
• Prevent re-triggering to same dest state: Skip anyState transitions whose destination matches the current crossFade target (canTransitionToSelf=false behavior, matching Unity)
• Fix _addTransition sorting boundary: HasExitTime transitions are now correctly sorted only within the [noExitTimeCount, count) range, avoiding comparison with noExitTime transitions
• Fix _checkNoExitTimeTransitions loop range: Loop now uses noExitTimeCount instead of count, preventing hasExitTime transitions from being incorrectly triggered before their exitTime

New in this PR

• Fix updateTransitionsIndex noExitTimeCount bug: When toggling hasExitTime at runtime, noExitTimeCount was not decremented, causing the noExitTime scan to read past its boundary
• Extract _tryCrossFadeInterrupt helper: Deduplicate identical interrupt check logic from _updateCrossFadeState and _updateCrossFadeFromPoseState, also absorbs the removed _checkCrossFadeInterrupt and _checkNoExitTimeTransition wrapper

Compared to #2885, this PR achieves the same functionality with ~80 fewer lines of code.

Test plan

• All 30 Animator tests pass
• New tests: anyState transition interrupts crossFade, noExitTime scan ignores exitTime transitions, hasExitTime runtime toggle maintains correct noExitTimeCount

[coderabbitai]

Walkthrough

Centralizes cross-fade interrupt logic into a new helper, replaces single-transition no-exit-time checks with a multi-transition scanner, fixes noExitTime bookkeeping in the transition collection, and adds tests covering anyState interrupts and hasExitTime toggles.

Changes

Cohort / File(s)	Summary
Animator core changes packages/core/src/animation/Animator.ts	Adds _tryCrossFadeInterrupt and _checkNoExitTimeTransitions; invokes interrupt checks before progressing cross-fades; replaces legacy single-transition no-exit-time checks; supports excluding the current cross-fade destination when scanning.
Transition collection logic packages/core/src/animation/AnimatorStateTransitionCollection.ts	Fixes updateTransitionsIndex to adjust noExitTimeCount when re-adding transitions; _addTransition keeps no-exit-time transitions at the front and bounds insertion/search to the exit-time region.
Tests tests/src/core/Animator.test.ts	Adds afterEach cleanup of state transitions; new tests for AnyState interrupting cross-fade, noExitTime scan ignoring exit-time transitions, and toggling hasExitTime validating noExitTimeCount and ordering.
Manifest package.json	Manifest referenced/updated in diff.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

• Allow anyState transitions to interrupt crossFade & fix transition bugs #2885: Implements the same cross-fade interruption and no-exit-time scanning refactor that skips the current cross-fade destination (strong code-level overlap).

Poem

🐇
I hopped through fades and checked each gate,
Skipped the exits, rearranged their state,
Counts in front, the transitions sing,
A little hop — interrupt! — and spring.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the two main changes: allowing anyState transitions to interrupt crossFade and fixing transition-related bugs in the animation system.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

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🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/animator-inter

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[augmentcode]

🤖 Augment PR Summary

Summary: This PR fixes Animator transition bookkeeping and reduces duplicated cross-fade interrupt logic.

Changes:

• Fixes AnimatorStateTransitionCollection.updateTransitionsIndex() to correctly decrement noExitTimeCount when a transition is toggled to hasExitTime=true, preventing out-of-bounds/no-exit-time scans from reading exit-time transitions.
• Removes the redundant _checkNoExitTimeTransition passthrough wrapper and calls _checkNoExitTimeTransitions directly.
• Extracts cross-fade interrupt checking into Animator._tryCrossFadeInterrupt() and reuses it in both cross-fade update paths.
• Maintains the “check before any update()” behavior so interrupts preserve events and let the new state consume the current deltaTime.

Tests:

• Simplifies test cleanup by relying on suite afterEach reset logic.
• Adds a new unit test validating noExitTimeCount stays correct when toggling hasExitTime at runtime.

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[augmentcode]

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[codecov]

Codecov Report

❌ Patch coverage is 92.85714% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.21%. Comparing base (ff88e8d) to head (4a42aa9).

Files with missing lines	Patch %	Lines
packages/core/src/animation/Animator.ts	94.44%	2 Missing ⚠️
...src/animation/AnimatorStateTransitionCollection.ts	83.33%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           dev/2.0    #2893   +/-   ##
========================================
  Coverage    83.21%   83.21%           
========================================
  Files          796      796           
  Lines        90398    90431   +33     
  Branches      9489     9499   +10     
========================================
+ Hits         75221    75254   +33     
  Misses       15095    15095           
  Partials        82       82           

Flag	Coverage Δ
unittests	83.21% <92.85%> (+<0.01%)	⬆️

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@packages/core/src/animation/Animator.ts`:
- Around line 1165-1183: The anyState exit-transition path can mutate
layerData.layerState via _applyTransition/_checkAnyAndEntryState and cause
_tryCrossFadeInterrupt to continue with stale state; after invoking
_checkNoExitTimeTransitions (or inside it) verify whether layerData.layerState
changed from the original currentDestState and, if so, call
_updateState(layerData, deltaTime, aniUpdate) and return true to abort the
crossfade; alternatively make _checkNoExitTimeTransitions return false when
_applyTransition returns null (indicating a state mutation) so
_tryCrossFadeInterrupt treats that as an interrupt—update the logic around
_tryCrossFadeInterrupt, _checkNoExitTimeTransitions, _applyTransition and
_checkAnyAndEntryState to perform this post-check using the layerData.layerState
and currentDestState symbols.