From 1ac643f1eecbbc7736a4124bb8ad31c865b07531 Mon Sep 17 00:00:00 2001
From: harshmandan <harshsinghmandan@gmail.com>
Date: Sat, 16 Aug 2025 23:37:40 +0530
Subject: [PATCH 1/2] fix: prevent component pre-mounting in async boundaries

---
 .../client/dom/blocks/svelte-component.js     | 38 ++++++++-----------
 1 file changed, 15 insertions(+), 23 deletions(-)

diff --git a/packages/svelte/src/internal/client/dom/blocks/svelte-component.js b/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
index be6611c96d11..02b6b5337cc1 100644
--- a/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
+++ b/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
@@ -4,7 +4,7 @@ import { EFFECT_TRANSPARENT } from '#client/constants';
 import { block, branch, pause_effect } from '../../reactivity/effects.js';
 import { current_batch } from '../../reactivity/batch.js';
 import { hydrate_next, hydrate_node, hydrating } from '../hydration.js';
-import { create_text, should_defer_append } from '../operations.js';
+import { should_defer_append } from '../operations.js';
 
 /**
  * @template P
@@ -27,19 +27,13 @@ export function component(node, get_component, render_fn) {
 	/** @type {Effect | null} */
 	var effect;
 
-	/** @type {DocumentFragment | null} */
-	var offscreen_fragment = null;
-
 	/** @type {Effect | null} */
 	var pending_effect = null;
 
 	function commit() {
-		if (offscreen_fragment) {
-			// remove the anchor
-			/** @type {Text} */ (offscreen_fragment.lastChild).remove();
-
-			anchor.before(offscreen_fragment);
-			offscreen_fragment = null;
+		if (effect) {
+			pause_effect(effect);
+			effect = null;
 		}
 
 		effect = pending_effect;
@@ -51,25 +45,23 @@ export function component(node, get_component, render_fn) {
 
 		var defer = should_defer_append();
 
-		if (effect) {
-			pause_effect(effect);
-			effect = null;
-		}
-
 		if (component) {
-			var target = anchor;
-
 			if (defer) {
-				offscreen_fragment = document.createDocumentFragment();
-				offscreen_fragment.append((target = create_text()));
 				if (effect) {
 					/** @type {Batch} */ (current_batch).skipped_effects.add(effect);
 				}
+				/** @type {Batch} */ (current_batch).add_callback(() => {
+					if (effect) {
+						pause_effect(effect);
+						effect = null;
+					}
+					effect = branch(() => render_fn(anchor, component));
+				});
+			} else {
+				pending_effect = branch(() => render_fn(anchor, component));
+				commit();
 			}
-			pending_effect = branch(() => render_fn(target, component));
-		}
-
-		if (defer) {
+		} else if (defer) {
 			/** @type {Batch} */ (current_batch).add_callback(commit);
 		} else {
 			commit();

From eebadcdd16f6fd712fb6c3c471ef2600088ab8d1 Mon Sep 17 00:00:00 2001
From: harshmandan <harshsinghmandan@gmail.com>
Date: Sun, 17 Aug 2025 00:12:36 +0530
Subject: [PATCH 2/2] chore: add changeset

---
 .changeset/green-lies-smell.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/green-lies-smell.md

diff --git a/.changeset/green-lies-smell.md b/.changeset/green-lies-smell.md
new file mode 100644
index 000000000000..bc266fb6529a
--- /dev/null
+++ b/.changeset/green-lies-smell.md
@@ -0,0 +1,5 @@
+---
+'svelte': minor
+---
+
+fix: prevent component pre-mounting in async boundaries