fix(svelte-store): preserve selector object identity

.changeset/svelte-selector-identity.md

@@ -0,0 +1,5 @@
+---
+'@tanstack/svelte-store': patch
+---
+
+Fix `useSelector` object selection comparisons by preserving raw value identity.

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

@@ -35,7 +35,7 @@ export function useSelector<TState, TSelected = NoInfer<TState>>(
   options: UseSelectorOptions<TSelected> = {},
 ): { readonly current: TSelected } {
   const compare = options.compare ?? defaultCompare
-  let slice = $state(selector(source.get()))
+  let slice = $state.raw(selector(source.get()))
 
   $effect(() => {
     const unsub = source.subscribe((s) => {

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

@@ -0,0 +1,35 @@
+<script lang="ts">
+  import { untrack } from 'svelte'
+  import { createStore } from '@tanstack/store'
+  import { useSelector } from '../src/index.svelte.js'
+
+  const store = createStore({
+    selected: { value: 1 },
+    ignored: 1,
+  })
+
+  const selected = useSelector(store, (state) => state.selected)
+
+  let renderCount = $state(0)
+
+  $effect(() => {
+    selected.current
+    untrack(() => {
+      renderCount++
+    })
+  })
+</script>
+
+<div>
+  <p>Number rendered: {renderCount}</p>
+  <p>Selected: {selected.current.value}</p>
+  <button
+    onclick={() =>
+      store.setState((state) => ({
+        ...state,
+        ignored: state.ignored + 1,
+      }))}
+  >
+    Update ignored
+  </button>
+</div>

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

@@ -3,6 +3,7 @@ import { render, waitFor } from '@testing-library/svelte'
 import { userEvent } from '@testing-library/user-event'
 import { shallow } from '../src/index.svelte.js'
 import TestBaseStore from './BaseStore.test.svelte'
+import TestObjectSelector from './ObjectSelector.test.svelte'
 import TestRerender from './Render.test.svelte'
 import TestValue from './Value.test.svelte'
 
@@ -28,6 +29,15 @@ describe('useSelector', () => {
     expect(getByText('Number rendered: 2')).toBeInTheDocument()
   })
 
+  it('preserves object identity for unchanged selector state', async () => {
+    const { getByRole, getByText } = render(TestObjectSelector)
+    expect(getByText('Number rendered: 1')).toBeInTheDocument()
+
+    await user.click(getByRole('button', { name: 'Update ignored' }))
+
+    expect(getByText('Number rendered: 1')).toBeInTheDocument()
+  })
+
   it('useSelector reads writable and readonly store state', async () => {
     const { getByText } = render(TestValue)
     expect(getByText('Value: 1')).toBeInTheDocument()