From fec2c20f60645bdf7d52b676c368a79028fdd0f9 Mon Sep 17 00:00:00 2001
From: paoloricciuti <ricciutipaolo@gmail.com>
Date: Mon, 13 Jan 2025 22:10:30 +0100
Subject: [PATCH 1/2] fix: never consider inert boundary effects

---
 .changeset/healthy-hairs-run.md                 |  5 +++++
 .../src/internal/client/reactivity/effects.js   |  6 ++++--
 .../samples/error-boundary-21/Child.svelte      |  3 +++
 .../samples/error-boundary-21/_config.js        | 17 +++++++++++++++++
 .../samples/error-boundary-21/main.svelte       | 14 ++++++++++++++
 5 files changed, 43 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/healthy-hairs-run.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/error-boundary-21/Child.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/error-boundary-21/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/error-boundary-21/main.svelte

diff --git a/.changeset/healthy-hairs-run.md b/.changeset/healthy-hairs-run.md
new file mode 100644
index 000000000000..5f0ccd5234fd
--- /dev/null
+++ b/.changeset/healthy-hairs-run.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: never consider inert boundary effects
diff --git a/packages/svelte/src/internal/client/reactivity/effects.js b/packages/svelte/src/internal/client/reactivity/effects.js
index 16f076eddeba..5f132894d0ce 100644
--- a/packages/svelte/src/internal/client/reactivity/effects.js
+++ b/packages/svelte/src/internal/client/reactivity/effects.js
@@ -35,7 +35,8 @@ import {
 	INSPECT_EFFECT,
 	HEAD_EFFECT,
 	MAYBE_DIRTY,
-	EFFECT_HAS_DERIVED
+	EFFECT_HAS_DERIVED,
+	BOUNDARY_EFFECT
 } from '../constants.js';
 import { set } from './sources.js';
 import * as e from '../errors.js';
@@ -142,7 +143,8 @@ function create_effect(type, fn, sync, push = true) {
 		effect.first === null &&
 		effect.nodes_start === null &&
 		effect.teardown === null &&
-		(effect.f & EFFECT_HAS_DERIVED) === 0;
+		(effect.f & EFFECT_HAS_DERIVED) === 0 &&
+		(effect.f & BOUNDARY_EFFECT) === 0;
 
 	if (!inert && !is_root && push) {
 		if (parent_effect !== null) {
diff --git a/packages/svelte/tests/runtime-runes/samples/error-boundary-21/Child.svelte b/packages/svelte/tests/runtime-runes/samples/error-boundary-21/Child.svelte
new file mode 100644
index 000000000000..ea60542af9cc
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/error-boundary-21/Child.svelte
@@ -0,0 +1,3 @@
+<script>
+	throw new Error();
+</script>
diff --git a/packages/svelte/tests/runtime-runes/samples/error-boundary-21/_config.js b/packages/svelte/tests/runtime-runes/samples/error-boundary-21/_config.js
new file mode 100644
index 000000000000..e301f83e6024
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/error-boundary-21/_config.js
@@ -0,0 +1,17 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	html: '<button></button><div>0</div>',
+	mode: ['client'],
+	test({ assert, target }) {
+		let btn = target.querySelector('button');
+		let div = target.querySelector('div');
+
+		flushSync(() => {
+			btn?.click();
+		});
+
+		assert.equal(div?.innerHTML, `1`);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/error-boundary-21/main.svelte b/packages/svelte/tests/runtime-runes/samples/error-boundary-21/main.svelte
new file mode 100644
index 000000000000..ed3140b1efb6
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/error-boundary-21/main.svelte
@@ -0,0 +1,14 @@
+<script>
+	import Child from "./Child.svelte"
+
+	let count = $state(0);
+</script>
+
+<button onclick={()=>count++}></button>
+<svelte:boundary>
+	<Child />
+
+	{#snippet failed()}
+		<div>{count}</div>
+	{/snippet}
+</svelte:boundary>

From ef044670fb15cdb52e92d1806ee8d125df9d3c0d Mon Sep 17 00:00:00 2001
From: paoloricciuti <ricciutipaolo@gmail.com>
Date: Mon, 13 Jan 2025 22:14:28 +0100
Subject: [PATCH 2/2] chore: inline bitwise

---
 packages/svelte/src/internal/client/reactivity/effects.js | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/svelte/src/internal/client/reactivity/effects.js b/packages/svelte/src/internal/client/reactivity/effects.js
index 5f132894d0ce..149cbd2d38ba 100644
--- a/packages/svelte/src/internal/client/reactivity/effects.js
+++ b/packages/svelte/src/internal/client/reactivity/effects.js
@@ -143,8 +143,7 @@ function create_effect(type, fn, sync, push = true) {
 		effect.first === null &&
 		effect.nodes_start === null &&
 		effect.teardown === null &&
-		(effect.f & EFFECT_HAS_DERIVED) === 0 &&
-		(effect.f & BOUNDARY_EFFECT) === 0;
+		(effect.f & (EFFECT_HAS_DERIVED | BOUNDARY_EFFECT)) === 0;
 
 	if (!inert && !is_root && push) {
 		if (parent_effect !== null) {