fix: ensure tracking returns true, even if in unowned (#15214)

* fix: ensure tracking returns true, even if in unowned

* fix: ensure tracking returns true, even if in unowned

* Update packages/svelte/tests/runtime-runes/samples/effect-tracking-unowned/main.svelte

---------

Co-authored-by: Simon H <[email protected]>

.changeset/long-moles-join.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: ensure tracking returns true, even if in unowned

packages/svelte/src/internal/client/reactivity/effects.js

@@ -164,13 +164,7 @@ function create_effect(type, fn, sync, push = true) {
  * @returns {boolean}
  */
 export function effect_tracking() {
-	if (active_reaction === null || untracking) {
-		return false;
-	}
-
-	// If it's skipped, that's because we're inside an unowned
-	// that is not being tracked by another reaction
-	return !skip_reaction;
+	return active_reaction !== null && !untracking;
 }
 
 /**

packages/svelte/tests/runtime-runes/samples/effect-tracking-unowned/_config.js

@@ -0,0 +1,16 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target, logs }) {
+		const b1 = target.querySelector('button');
+
+		b1?.click();
+		flushSync();
+
+		assert.htmlEqual(
+			target.innerHTML,
+			`<o>Store: new</o><p>Text: new message</p><button>Change Store</button>`
+		);
+	}
+});

packages/svelte/tests/runtime-runes/samples/effect-tracking-unowned/main.svelte

@@ -0,0 +1,12 @@
+<script>
+	import { writable, fromStore, toStore } from "svelte/store";
+
+	const store = writable("previous");
+	let text = $derived(fromStore(store).current + " message");
+
+	text; // read derived in a non-tracking context
+</script>
+
+<o>Store: {$store}</o>
+<p>Text: {text}</p>
+<button onclick={() => { store.set("new"); }}>Change Store</button>