From bc874ba219d77055469e8eaf4d2a4cd78342c8c4 Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <trueadm@users.noreply.github.com>
Date: Tue, 1 Apr 2025 15:22:14 +0100
Subject: [PATCH 1/3] fix: ensure clearing of old values happens indepedent of
 root flushes

---
 .changeset/kind-elephants-behave.md            | 5 +++++
 packages/svelte/src/internal/client/runtime.js | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/kind-elephants-behave.md

diff --git a/.changeset/kind-elephants-behave.md b/.changeset/kind-elephants-behave.md
new file mode 100644
index 000000000000..41c6711c5815
--- /dev/null
+++ b/.changeset/kind-elephants-behave.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: ensure clearing of old values happens indepedent of root flushes
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index a5d26412a4e6..a69181da986a 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -692,6 +692,7 @@ function flush_queued_root_effects() {
 				var collected_effects = process_effects(root_effects[i]);
 				flush_queued_effects(collected_effects);
 			}
+			old_values.clear();
 		}
 	} finally {
 		is_flushing = false;
@@ -701,7 +702,6 @@ function flush_queued_root_effects() {
 		if (DEV) {
 			dev_effect_stack = [];
 		}
-		old_values.clear();
 	}
 }
 

From dfa435030cfbec1806b0b50209034cd47f8b01c8 Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <trueadm@users.noreply.github.com>
Date: Tue, 1 Apr 2025 15:56:10 +0100
Subject: [PATCH 2/3] lint

---
 .changeset/kind-elephants-behave.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.changeset/kind-elephants-behave.md b/.changeset/kind-elephants-behave.md
index 41c6711c5815..f52dc1fd36a0 100644
--- a/.changeset/kind-elephants-behave.md
+++ b/.changeset/kind-elephants-behave.md
@@ -2,4 +2,4 @@
 'svelte': patch
 ---
 
-fix: ensure clearing of old values happens indepedent of root flushes
+fix: ensure clearing of old values happens independent of root flushes

From 3b44fe65c6cc7790bcde40cd035a8d84b777380c Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <trueadm@users.noreply.github.com>
Date: Tue, 1 Apr 2025 15:56:22 +0100
Subject: [PATCH 3/3] test

---
 .../samples/onmount-prop-access/Component.svelte   | 12 ++++++++++++
 .../samples/onmount-prop-access/_config.js         |  7 +++++++
 .../samples/onmount-prop-access/main.svelte        | 14 ++++++++++++++
 3 files changed, 33 insertions(+)
 create mode 100644 packages/svelte/tests/runtime-runes/samples/onmount-prop-access/Component.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/onmount-prop-access/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/onmount-prop-access/main.svelte

diff --git a/packages/svelte/tests/runtime-runes/samples/onmount-prop-access/Component.svelte b/packages/svelte/tests/runtime-runes/samples/onmount-prop-access/Component.svelte
new file mode 100644
index 000000000000..b5da702fa7b2
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/onmount-prop-access/Component.svelte
@@ -0,0 +1,12 @@
+<script>
+	import { onMount } from 'svelte'
+
+	let thing = $state(0)
+
+	onMount(() => {
+		thing = 1;
+		return () => {
+			console.log(thing);
+		}
+	})
+</script>
diff --git a/packages/svelte/tests/runtime-runes/samples/onmount-prop-access/_config.js b/packages/svelte/tests/runtime-runes/samples/onmount-prop-access/_config.js
new file mode 100644
index 000000000000..0d24e265d3ab
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/onmount-prop-access/_config.js
@@ -0,0 +1,7 @@
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, logs }) {
+		assert.deepEqual(logs, [1]);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/onmount-prop-access/main.svelte b/packages/svelte/tests/runtime-runes/samples/onmount-prop-access/main.svelte
new file mode 100644
index 000000000000..92746760a484
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/onmount-prop-access/main.svelte
@@ -0,0 +1,14 @@
+<script>
+	import { onMount } from "svelte"
+	import Component from './Component.svelte';
+
+	let key = $state(0);
+
+	onMount(() => {
+		key = 1;
+	})
+</script>
+
+{#key key}
+	<Component />
+{/key}