fix: avoid render-phase shared value read in getCurrentIndex (fix #829)

[dohooo]

Summary

This PR fixes the render-phase shared value warning reported in #829:

Reading from value during component render...

The warning was triggered when getCurrentIndex() was called during React render (for example through an imperative ref read during rerender).

1) Trigger chain

• Carousel exposes imperative getCurrentIndex() from useCarouselController.
• Before this fix, getCurrentIndex() read index.value directly.
• If user code calls ref.current?.getCurrentIndex() during component render, Reanimated strict logger reports render-phase shared value access.

2) Fix strategy

• Keep a JS-side index snapshot (sharedIndex.current) as the source for imperative reads.
• Change getCurrentIndex() to read sharedIndex.current instead of index.value.
• Add syncSharedIndex() and update it in next/prev/to paths so imperative commands remain consistent immediately.
• Keep animation/gesture logic unchanged (no warning silencing, no logger suppression).

3) Regression test

Added a warning-level regression test in src/components/Carousel.test.tsx:

• Captures Reanimated logger output for Reading from value during component render.
• Reproduces minimal scenario: rerender + imperative getCurrentIndex() read during render.
• Asserts no warning is emitted after the fix.

This test is Red before the fix and Green after.

4) Validation

Executed:

yarn test src/components/Carousel.test.tsx src/hooks/useCarouselController.test.tsx src/components/Pagination/Pagination.test.tsx --runInBand --verbose=false

Result:

• 3 test suites passed
• 80 tests passed

Notes

• This does not mute or disable Reanimated strict warnings.
• Existing interaction behavior remains covered by controller and carousel tests.

Closes #829.

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Project	Deployment	Actions	Updated (UTC)
react-native-reanimated-carousel	Building	Preview, Comment	Mar 2, 2026 8:49am

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Latest commit: 913c603

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Related Documentation

Checked 4 published document(s) in 1 knowledge base(s). No updates required.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.44%. Comparing base (5289d9d) to head (913c603).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #895      +/-   ##
==========================================
+ Coverage   84.06%   84.44%   +0.37%     
==========================================
  Files          37       37              
  Lines        1042     1048       +6     
  Branches      364      364              
==========================================
+ Hits          876      885       +9     
  Misses         67       67              
+ Partials       99       96       -3     

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