From 6651f5e236de1bc9c551ac83224b1d37f24e5ec2 Mon Sep 17 00:00:00 2001
From: paoloricciuti <ricciutipaolo@gmail.com>
Date: Thu, 9 Oct 2025 10:41:19 +0200
Subject: [PATCH] fix: generate correct  SSR code for the case where `pending`
 is an attribute

---
 .changeset/spicy-rabbits-drive.md                         | 5 +++++
 .../phases/3-transform/server/visitors/SvelteBoundary.js  | 7 +++++--
 .../samples/boundary-pending-prop-async/_config.js        | 3 +++
 .../samples/boundary-pending-prop-async/_expected.html    | 1 +
 .../samples/boundary-pending-prop-async/main.svelte       | 8 ++++++++
 5 files changed, 22 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/spicy-rabbits-drive.md
 create mode 100644 packages/svelte/tests/server-side-rendering/samples/boundary-pending-prop-async/_config.js
 create mode 100644 packages/svelte/tests/server-side-rendering/samples/boundary-pending-prop-async/_expected.html
 create mode 100644 packages/svelte/tests/server-side-rendering/samples/boundary-pending-prop-async/main.svelte

diff --git a/.changeset/spicy-rabbits-drive.md b/.changeset/spicy-rabbits-drive.md
new file mode 100644
index 0000000000..01834294e1
--- /dev/null
+++ b/.changeset/spicy-rabbits-drive.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: generate correct  SSR code for the case where `pending` is an attribute
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/SvelteBoundary.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/SvelteBoundary.js
index b272870ac3..41a18cf52d 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/SvelteBoundary.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/SvelteBoundary.js
@@ -43,11 +43,14 @@ export function SvelteBoundary(node, context) {
 			);
 			const pending = b.call(callee, b.id('$$renderer'));
 			const block = /** @type {BlockStatement} */ (context.visit(node.fragment));
+			const statement = node.fragment.metadata.has_await
+				? create_async_block(b.block([block]))
+				: block;
 			context.state.template.push(
 				b.if(
 					callee,
-					b.block(build_template([block_open_else, pending, block_close])),
-					b.block(build_template([block_open, block, block_close]))
+					b.block([b.stmt(pending)]),
+					b.block(build_template([block_open, statement, block_close]))
 				)
 			);
 		} else {
diff --git a/packages/svelte/tests/server-side-rendering/samples/boundary-pending-prop-async/_config.js b/packages/svelte/tests/server-side-rendering/samples/boundary-pending-prop-async/_config.js
new file mode 100644
index 0000000000..f47bee71df
--- /dev/null
+++ b/packages/svelte/tests/server-side-rendering/samples/boundary-pending-prop-async/_config.js
@@ -0,0 +1,3 @@
+import { test } from '../../test';
+
+export default test({});
diff --git a/packages/svelte/tests/server-side-rendering/samples/boundary-pending-prop-async/_expected.html b/packages/svelte/tests/server-side-rendering/samples/boundary-pending-prop-async/_expected.html
new file mode 100644
index 0000000000..ac7cd985f1
--- /dev/null
+++ b/packages/svelte/tests/server-side-rendering/samples/boundary-pending-prop-async/_expected.html
@@ -0,0 +1 @@
+<!--[--><!---->Loading...<!--]-->
\ No newline at end of file
diff --git a/packages/svelte/tests/server-side-rendering/samples/boundary-pending-prop-async/main.svelte b/packages/svelte/tests/server-side-rendering/samples/boundary-pending-prop-async/main.svelte
new file mode 100644
index 0000000000..7e0d4c62ea
--- /dev/null
+++ b/packages/svelte/tests/server-side-rendering/samples/boundary-pending-prop-async/main.svelte
@@ -0,0 +1,8 @@
+{#snippet pending()}
+	Loading...
+{/snippet}
+
+<svelte:boundary pending={pending}>
+	{@const data = await Promise.resolve('hello')}
+	<p>{data}</p>
+</svelte:boundary>
\ No newline at end of file