From 073f4d8911a63164d685152cef973631c3110dc8 Mon Sep 17 00:00:00 2001
From: tomoam <29677552+tomoam@users.noreply.github.com>
Date: Mon, 17 Feb 2025 23:52:56 +0900
Subject: [PATCH] fix: prevent writable store value from becoming a proxy when
 reassigning using $-prefix (#15283)

fixes #15281
---
 .changeset/lovely-chairs-compete.md                   |  5 +++++
 .../client/visitors/AssignmentExpression.js           |  1 +
 .../samples/store-reassign-object/_config.js          |  7 +++++++
 .../samples/store-reassign-object/main.svelte         | 11 +++++++++++
 4 files changed, 24 insertions(+)
 create mode 100644 .changeset/lovely-chairs-compete.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/store-reassign-object/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/store-reassign-object/main.svelte

diff --git a/.changeset/lovely-chairs-compete.md b/.changeset/lovely-chairs-compete.md
new file mode 100644
index 000000000000..d311a3dde6f0
--- /dev/null
+++ b/.changeset/lovely-chairs-compete.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: prevent writable store value from becoming a proxy when reassigning using $-prefix
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 0c70f7e00cda..a8c615af936f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -118,6 +118,7 @@ function build_assignment(operator, left, right, context) {
 			binding.kind !== 'prop' &&
 			binding.kind !== 'bindable_prop' &&
 			binding.kind !== 'raw_state' &&
+			binding.kind !== 'store_sub' &&
 			context.state.analysis.runes &&
 			should_proxy(right, context.state.scope) &&
 			is_non_coercive_operator(operator)
diff --git a/packages/svelte/tests/runtime-runes/samples/store-reassign-object/_config.js b/packages/svelte/tests/runtime-runes/samples/store-reassign-object/_config.js
new file mode 100644
index 000000000000..f9a329889d21
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/store-reassign-object/_config.js
@@ -0,0 +1,7 @@
+import { test } from '../../test';
+
+export default test({
+	async test({ target, assert }) {
+		assert.htmlEqual(target.innerHTML, `<p>bar</p>`);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/store-reassign-object/main.svelte b/packages/svelte/tests/runtime-runes/samples/store-reassign-object/main.svelte
new file mode 100644
index 000000000000..ecffbb2d837c
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/store-reassign-object/main.svelte
@@ -0,0 +1,11 @@
+<script>
+	import { writable } from "svelte/store";
+
+	const obj = writable({ name: 'foo' });
+
+	$obj = { name: 'bar' };
+
+	const clone = structuredClone($obj);
+</script>
+
+<p>{clone.name}</p>