fix(preact-store): recompute selections when selectors change

[KevinVandy]

🎯 Changes

Fix a regression introduced by #318 in @tanstack/preact-store@0.13.1: changing a selector while the store snapshot stays unchanged returns the previous selector's result. For example, useSelector(store, (state) => state[modifier]) keeps returning the Alt selection after modifier changes to Control. This surfaced in TanStack Hotkeys while upgrading the adapter.

Replace the shared snapshot-cache ref with a selector-local closure created by useMemo([selector]). A new selector gets a fresh cache, while repeated reads through the same selector still reuse the result for an unchanged snapshot. This preserves the protection against render loops from selectors returning fresh arrays or objects and retains custom equality behavior.

Add five test cases covering inline and memoized selectors with changing props, stable-selector caching, equality across selector changes, and fresh array selections across parent rerenders and store updates. Four of the new cases fail on the previous implementation; all pass with the fix, including the existing array-selector regression test from #318.

Validation

• CI=1 NX_DAEMON=false pnpm test:pr passes all 17 affected tasks: package tests (55 passing runtime/type test cases), TypeScript 5.6/5.7/5.8/6.0, ESLint, build/publint, workspace checks, and affected Preact example checks/builds.
• Prettier and git diff --check pass.
• pnpm changeset status confirms a patch release for @tanstack/preact-store only.

✅ Checklist

• I have followed the steps in the Contributing guide.
• I have tested this code locally with pnpm test:pr.

🚀 Release Impact

• This change affects published code, and I have generated a changeset.
• This change is docs/CI/dev-only (no release).

Summary by CodeRabbit

• Bug Fixes
  • Fixed stale selector results when selector logic changes, including when it depends on updated component props, even if the store snapshot has not changed.
  • Preserved efficient snapshot caching for selectors that return new arrays or objects, while ensuring selections are recalculated when needed.

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📥 Commits

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📒 Files selected for processing (5)

• .changeset/bright-keys-update.md
• docs/framework/preact/reference/functions/useSelector.md
• docs/framework/preact/reference/interfaces/UseSelectorOptions.md
• packages/preact-store/src/useSelector.ts
• packages/preact-store/tests/index.test.tsx

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Command	Status	Duration	Result
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☁️ Nx Cloud last updated this comment at 2026-09-23 18:33:12 UTC

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commit: 9927252