From 7c4f5956d49830c9e600fa9e90bbc14790f2f5ff Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 11 Feb 2026 11:05:07 -0500
Subject: [PATCH] add test

---
 .../derived-server-memoization/_config.js     |  3 ++
 .../derived-server-memoization/main.svelte    | 29 +++++++++++++++++++
 .../state.svelte.js                           | 20 +++++++++++++
 3 files changed, 52 insertions(+)
 create mode 100644 packages/svelte/tests/runtime-runes/samples/derived-server-memoization/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/derived-server-memoization/main.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/derived-server-memoization/state.svelte.js

diff --git a/packages/svelte/tests/runtime-runes/samples/derived-server-memoization/_config.js b/packages/svelte/tests/runtime-runes/samples/derived-server-memoization/_config.js
new file mode 100644
index 0000000000..f47bee71df
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/derived-server-memoization/_config.js
@@ -0,0 +1,3 @@
+import { test } from '../../test';
+
+export default test({});
diff --git a/packages/svelte/tests/runtime-runes/samples/derived-server-memoization/main.svelte b/packages/svelte/tests/runtime-runes/samples/derived-server-memoization/main.svelte
new file mode 100644
index 0000000000..bc942a6fa2
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/derived-server-memoization/main.svelte
@@ -0,0 +1,29 @@
+<script>
+	import { reset, increment, get, count } from './state.svelte.js';
+
+	reset();
+	get();
+	increment();
+	get();
+
+	// non-render-bound deriveds recalculate
+	if (count !== 2) {
+		throw new Error(`count was ${count}`);
+	}
+
+	let local_count = 0;
+
+	let s = $state(0);
+	let d = $derived.by(() => {
+		local_count += 1;
+		return s * 2;
+	});
+
+	d;
+	d;
+
+	// render-bound deriveds do not
+	if (local_count !== 1) {
+		throw new Error(`local_count was ${local_count}`);
+	}
+</script>
diff --git a/packages/svelte/tests/runtime-runes/samples/derived-server-memoization/state.svelte.js b/packages/svelte/tests/runtime-runes/samples/derived-server-memoization/state.svelte.js
new file mode 100644
index 0000000000..df8f6f4795
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/derived-server-memoization/state.svelte.js
@@ -0,0 +1,20 @@
+let s = $state(0);
+let d = $derived.by(() => {
+	count += 1;
+	return s * 2;
+});
+
+export let count = 0;
+
+export function reset() {
+	count = 0;
+	s = 0;
+}
+
+export function increment() {
+	s += 1;
+}
+
+export function get() {
+	return d;
+}