Fix preact selector stability

[crutchcorn]

This PR fixes the ability to run non-stable Preact selectors in useSelector; preventing infinite loops

Summary by CodeRabbit

• Bug Fixes

  • useSelector now properly handles unstable selector functions, reducing unnecessary component re-renders and improving performance when utilizing non-memoized selectors.

• Tests

  • Added test coverage to verify useSelector correctly processes complex selector patterns, including those returning arrays and other data structures.

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

Walkthrough

The preact-store useSelector hook now memoizes selector results based on snapshot identity using a ref-backed cache, preventing unnecessary selector invocations. Both preact and react store implementations include matching test cases confirming the behavior works correctly with array selectors that depend on multiple store fields.

Changes

Selector memoization enhancement

Layer / File(s)	Summary
Memoization mechanism packages/preact-store/src/useSelector.ts	A ref stores the last snapshot and selected value; memoizedSelector callback returns cached result when snapshot is identity-equal, otherwise recomputes and updates cache.
Hook integration packages/preact-store/src/useSelector.ts	useSyncExternalStoreWithSelector receives memoizedSelector instead of raw selector, preserving subscription and compare logic.
Test coverage packages/preact-store/tests/index.test.tsx, packages/react-store/tests/index.test.tsx	Preact and react tests verify useSelector handles array selectors and re-renders when individual source fields update.
Release documentation .changeset/fancy-colts-rush.md	Changeset documents a patch bump for @tanstack/preact-store noting that useSelector now handles unstable selector functions.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Poem

🐰 A cache for the selectors so keen,
No snapshot alike shall be seen,
Arrays dance twice,
With memoized splice,
The preact store now runs lean! ✨

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The PR description explains the fix briefly, but does not follow the provided template structure with sections for 'Changes' and 'Checklist' or 'Release Impact'.	Update the description to follow the repository template: add a '## 🎯 Changes' section with details, and include the '## ✅ Checklist' and '## 🚀 Release Impact' sections with appropriate checkmarks.
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Fix preact selector stability' is directly related to the main change, which is fixing preact selector stability by memoizing selectors to prevent infinite loops.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix-preact-selector-stability

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[nx-cloud]

View your CI Pipeline Execution ↗ for commit 1ce4418

Command	Status	Duration	Result
nx affected --targets=test:sherif,test:knip,tes...	✅ Succeeded	34s	View ↗
nx run-many --target=build --exclude=examples/**	✅ Succeeded	2s	View ↗

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☁️ Nx Cloud last updated this comment at 2026-05-08 20:50:21 UTC

[github-actions]

🚀 Changeset Version Preview

1 package(s) bumped directly, 0 bumped as dependents.

🟩 Patch bumps

Package	Version	Reason
@tanstack/preact-store	0.13.0 → 0.13.1	Changeset

[pkg-pr-new]

@tanstack/angular-store

npm i https://pkg.pr.new/@tanstack/angular-store@318

@tanstack/preact-store

npm i https://pkg.pr.new/@tanstack/preact-store@318

@tanstack/react-store

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@tanstack/solid-store

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@tanstack/store

npm i https://pkg.pr.new/@tanstack/store@318

@tanstack/svelte-store

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@tanstack/vue-store

npm i https://pkg.pr.new/@tanstack/vue-store@318

commit: 1ce4418