fix(svelte-store): use .raw in useSelector to avoid proxy equality mismatch

[grzdev]

Summary of Changes

In Svelte 5, using $state(selector(source.get())) wraps any selected objects or arrays in deeply reactive proxies. This causes several issues when using useSelector:

1. Comparing compare(slice, data) compares the reactive proxy in slice with the raw object from data. Under default reference comparison (===), a Proxy never strictly equals the raw target object, causing false positives and triggering unnecessary updates on unaffected objects.
2. Svelte 5 triggers state_proxy_equality_mismatch warnings / errors in development when checking proxy vs raw object equality.
3. Callers reading storeVal.current receive a proxy rather than the raw object reference, defeating reference equality checks across component boundaries.

This change switches useSelector's internal state holder to let slice = $state.raw(selector(source.get())). Because the selector state holder is updated via reassignment (slice = data), $state.raw retains full reactive signaling when values change while preserving reference identity and avoiding unwanted proxy wrapping.

Validation

• Added a unit test in packages/svelte-store ensuring object reference identity is preserved and unchanged object selections do not trigger spurious re-renders.
• Verified all vitest tests and svelte-check type checks pass.

Summary by CodeRabbit

• Bug Fixes
  • Fixed object selection in @tanstack/svelte-store to preserve original object references and avoid unnecessary re-renders when unrelated store values change.
  • Updates to nested selected values continue to trigger re-renders.

[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: c6dafc75-d41d-46a3-942e-8bb510176492

📥 Commits

Reviewing files that changed from the base of the PR and between c1a40d4 and 48ca363.

📒 Files selected for processing (4)

• .changeset/svelte-store-raw-state.md
• packages/svelte-store/src/useSelector.svelte.ts
• packages/svelte-store/tests/ObjectRender.test.svelte
• packages/svelte-store/tests/index.test.ts

Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 2 remain after this review.

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📝 Walkthrough

Walkthrough

useSelector now initializes its selected value with $state.raw. Tests check that the selected object retains its original reference, unrelated updates do not trigger a re-render, and nested updates do.

Changes

Selector state

Layer / File(s)	Summary
Initialize selection with raw state packages/svelte-store/src/useSelector.svelte.ts, .changeset/svelte-store-raw-state.md	useSelector initializes slice with $state.raw instead of $state. A patch changeset records the change.
Verify object selection behavior packages/svelte-store/tests/ObjectRender.test.svelte, packages/svelte-store/tests/index.test.ts	A new test checks selected-object identity and render behavior after unrelated and nested store updates.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Possibly related PRs

• TanStack/store#364: Both changes initialize useSelector state with $state.raw and cover raw object identity.

Merge Risk: ⚪ Minimal · up to 48ca3

The selector change has no identified issue requiring a fix before merge.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description explains the motivation, implementation, and validation. It does not include the required ## 🎯 Changes, ## ✅ Checklist, or ## 🚀 Release Impact sections, and it does not record th…	Add the required template sections. Mark the contributing-guide and pnpm test:pr checklist items. Confirm the release impact by selecting the published-code option and noting the generated changeset, or select the docs/CI/dev-only option …

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: using raw state in useSelector to prevent proxy equality mismatches.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files. (2 skipped: 2 …
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.

Full details: Description check

Explanation

The description explains the motivation, implementation, and validation. It does not include the required ## 🎯 Changes, ## ✅ Checklist, or ## 🚀 Release Impact sections, and it does not record the checklist status or changeset impact.

Resolution

Add the required template sections. Mark the contributing-guide and pnpm test:pr checklist items. Confirm the release impact by selecting the published-code option and noting the generated changeset, or select the docs/CI/dev-only option if applicable.

• Fix all pre-merge checks with AI

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🧪 Generate unit tests (beta)

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Warning

Some tools did not complete. Review the errors below.

🔧 ESLint

If the error stems from missing dependencies, add them to the package.json file. For unrecoverable errors (e.g., due to private dependencies), disable the tool in the CodeRabbit configuration.

packages/svelte-store/src/useSelector.svelte.ts

ESLint skipped: missing config or dependency (missing-dependency). The ESLint configuration references a package that is not available in the sandbox.

packages/svelte-store/tests/ObjectRender.test.svelte

ESLint skipped: the matched ESLint configuration already failed (missing-dependency).

packages/svelte-store/tests/index.test.ts

ESLint skipped: the matched ESLint configuration already failed (missing-dependency).

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[crutchcorn]

Sorry, dupe of #364 which just got merged