From 8f88198287c9618768bbe3b98496223147572de6 Mon Sep 17 00:00:00 2001
From: cyphercodes <cyphercodes@users.noreply.github.com>
Date: Wed, 29 Apr 2026 01:56:51 +0300
Subject: [PATCH] fix(slots): unwrap conditional slot callbacks

---
 .changeset/tender-slots-unwrap.md                   |  5 +++++
 packages/astro/src/core/render/slots.ts             | 11 +++++++++--
 packages/astro/test/astro-slots.test.ts             |  7 +++++++
 .../src/components/ConditionalSlottedCallback.astro |  8 ++++++++
 .../src/pages/conditional-slotted-callback.astro    | 13 +++++++++++++
 5 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/tender-slots-unwrap.md
 create mode 100644 packages/astro/test/fixtures/astro-slots/src/components/ConditionalSlottedCallback.astro
 create mode 100644 packages/astro/test/fixtures/astro-slots/src/pages/conditional-slotted-callback.astro

diff --git a/.changeset/tender-slots-unwrap.md b/.changeset/tender-slots-unwrap.md
new file mode 100644
index 000000000000..24bb45545a12
--- /dev/null
+++ b/.changeset/tender-slots-unwrap.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fix conditional named slot callbacks receiving arguments from `Astro.slots.render()`.
diff --git a/packages/astro/src/core/render/slots.ts b/packages/astro/src/core/render/slots.ts
index 1d8abf67d66c..4234e6fb78fc 100644
--- a/packages/astro/src/core/render/slots.ts
+++ b/packages/astro/src/core/render/slots.ts
@@ -1,5 +1,6 @@
 import { type ComponentSlots, renderSlotToString } from '../../runtime/server/index.js';
 import { renderJSX } from '../../runtime/server/jsx.js';
+import { isRenderTemplateResult } from '../../runtime/server/render/astro/index.js';
 import { chunkToString } from '../../runtime/server/render/index.js';
 import { isRenderInstruction } from '../../runtime/server/render/instruction.js';
 import type { SSRResult } from '../../types/public/internal.js';
@@ -8,9 +9,15 @@ import type { AstroLogger } from '../logger/core.js';
 
 function getFunctionExpression(slot: any) {
 	if (!slot) return;
-	const expressions = slot?.expressions?.filter((e: unknown) => isRenderInstruction(e) === false);
+	const expressions = slot?.expressions?.filter(
+		(e: unknown) => isRenderInstruction(e) === false || isRenderTemplateResult(e),
+	);
 	if (expressions?.length !== 1) return;
-	return expressions[0] as (...args: any[]) => any;
+	const expression = expressions[0];
+	if (isRenderTemplateResult(expression)) {
+		return getFunctionExpression(expression);
+	}
+	return expression as (...args: any[]) => any;
 }
 
 export class Slots {
diff --git a/packages/astro/test/astro-slots.test.ts b/packages/astro/test/astro-slots.test.ts
index b50fb3ce9a66..2c140ae66804 100644
--- a/packages/astro/test/astro-slots.test.ts
+++ b/packages/astro/test/astro-slots.test.ts
@@ -182,6 +182,13 @@ describe('Slots', () => {
 		assert.deepEqual(afterDiv.text(), 'Test Content AFTER');
 	});
 
+	it('Arguments can be passed to conditional named slots with Astro.slots.render()', async () => {
+		const html = await fixture.readFile('/conditional-slotted-callback/index.html');
+		const $ = cheerio.load(html);
+
+		assert.equal($('#conditional-block').text(), 'Block: block');
+	});
+
 	it('Unused slot builds without error', async () => {
 		const html = await fixture.readFile('/unused-slot/index.html');
 		const $ = cheerio.load(html);
diff --git a/packages/astro/test/fixtures/astro-slots/src/components/ConditionalSlottedCallback.astro b/packages/astro/test/fixtures/astro-slots/src/components/ConditionalSlottedCallback.astro
new file mode 100644
index 000000000000..acc631cca546
--- /dev/null
+++ b/packages/astro/test/fixtures/astro-slots/src/components/ConditionalSlottedCallback.astro
@@ -0,0 +1,8 @@
+---
+let html = '';
+if (Astro.slots.has('block')) {
+	html = await Astro.slots.render('block', [{ test: 'block' }]);
+}
+---
+
+<Fragment set:html={html} />
diff --git a/packages/astro/test/fixtures/astro-slots/src/pages/conditional-slotted-callback.astro b/packages/astro/test/fixtures/astro-slots/src/pages/conditional-slotted-callback.astro
new file mode 100644
index 000000000000..5dc1bc158638
--- /dev/null
+++ b/packages/astro/test/fixtures/astro-slots/src/pages/conditional-slotted-callback.astro
@@ -0,0 +1,13 @@
+---
+import ConditionalSlottedCallback from '../components/ConditionalSlottedCallback.astro';
+---
+
+<ConditionalSlottedCallback>
+	{
+		true && (
+			<fragment slot="block">
+				{({ test }) => <div id="conditional-block">Block: {test}</div>}
+			</fragment>
+		)
+	}
+</ConditionalSlottedCallback>