Add additional scoping for head buffering (#6152)

* Add additional scoping for head buffering

* Add test for direct usage of nested component

* Add special scoping for Astro.scopes.render()

* Generate propagation map during the build

* Move to a maybeHead instruction

* Properly serialize for SSR

* More conservative scoping

* Maybe had should honor result._metadata.hasRenderedHead

* Properly type slots

* Allow template result to be passed

* Add changeset

14 files changed, 150 insertions, 0 deletions

diff --git a/packages/integrations/mdx/test/css-head-mdx.test.js b/packages/integrations/mdx/test/css-head-mdx.test.js
index 2b1dcdfe7..c38f23701 100644
--- a/packages/integrations/mdx/test/css-head-mdx.test.js
+++ b/packages/integrations/mdx/test/css-head-mdx.test.js
@@ -29,5 +29,32 @@ describe('Head injection w/ MDX', () => {
 			const scripts = document.querySelectorAll('head script[type=module]');
 			expect(scripts).to.have.a.lengthOf(1);
 		});
+
+		it('injects into the head for content collections', async () => {
+			const html = await fixture.readFile('/posts/test/index.html');
+			const { document } = parseHTML(html);
+
+			const links = document.querySelectorAll('head link[rel=stylesheet]');
+			expect(links).to.have.a.lengthOf(1);
+		});
+
+		it('injects content from a component using Content#render()', async () => {
+			const html = await fixture.readFile('/DirectContentUsage/index.html');
+			const { document } = parseHTML(html);
+
+			const links = document.querySelectorAll('head link[rel=stylesheet]');
+			expect(links).to.have.a.lengthOf(1);
+
+			const scripts = document.querySelectorAll('head script[type=module]');
+			expect(scripts).to.have.a.lengthOf(2);
+		});
+
+		it('Using component using slots.render() API', async () => {
+			const html = await fixture.readFile('/remote/index.html');
+			const { document } = parseHTML(html);
+
+			const links = document.querySelectorAll('head link[rel=stylesheet]');
+			expect(links).to.have.a.lengthOf(1);
+		});
 	});
 });
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/package.json b/packages/integrations/mdx/test/fixtures/css-head-mdx/package.json
new file mode 100644
index 000000000..3c3c1e5a5
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/package.json
@@ -0,0 +1,10 @@
+{
+  "name": "@test/mdx-css-head-mdx",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "astro": "workspace:*",
+    "@astrojs/mdx": "workspace:*",
+    "astro-remote": "0.2.3"
+  }
+}
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/src/components/P.astro b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/components/P.astro
new file mode 100644
index 000000000..071e08a12
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/components/P.astro
@@ -0,0 +1,3 @@
+<p>
+  <slot />
+</p>
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/src/components/SmallCaps.astro b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/components/SmallCaps.astro
new file mode 100644
index 000000000..a0bd6e1f1
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/components/SmallCaps.astro
@@ -0,0 +1,3 @@
+---
+---
+<span style={{fontVariant: "small-caps"}}><slot /></span>
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/src/components/UsingMdx.astro b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/components/UsingMdx.astro
new file mode 100644
index 000000000..1804388b0
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/components/UsingMdx.astro
@@ -0,0 +1,8 @@
+---
+import { getEntryBySlug } from 'astro:content';
+
+const launchWeek = await getEntryBySlug('blog', 'using-mdx');
+const { Content } = await launchWeek.render();
+---
+
+<Content />
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/src/components/WithHoistedScripts.astro b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/components/WithHoistedScripts.astro
new file mode 100644
index 000000000..0b8c4445f
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/components/WithHoistedScripts.astro
@@ -0,0 +1,6 @@
+---
+---
+
+<script>
+	console.log('hoisted')
+	</script>
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/src/content/blog/_styles.css b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/content/blog/_styles.css
new file mode 100644
index 000000000..1379b29c0
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/content/blog/_styles.css
@@ -0,0 +1,3 @@
+body {
+  color: red !important;
+}
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/src/content/blog/using-mdx.mdx b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/content/blog/using-mdx.mdx
new file mode 100644
index 000000000..917fc3331
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/content/blog/using-mdx.mdx
@@ -0,0 +1,6 @@
+import './_styles.css';
+import WithHoistedScripts from '../../components/WithHoistedScripts.astro';
+
+# Using mdx
+
+<WithHoistedScripts />
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/src/content/posts/test.mdx b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/content/posts/test.mdx
new file mode 100644
index 000000000..0bb1153ca
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/content/posts/test.mdx
@@ -0,0 +1,5 @@
+---
+title: Testing
+---
+
+<SmallCaps>A test file</SmallCaps>
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/src/layouts/ContentLayout.astro b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/layouts/ContentLayout.astro
new file mode 100644
index 000000000..7b234e868
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/layouts/ContentLayout.astro
@@ -0,0 +1,24 @@
+---
+export interface Props {
+	title: string;
+}
+
+const { title } = Astro.props;
+---
+
+<!DOCTYPE html>
+<html lang="en">
+	<head>
+		<meta charset="UTF-8" />
+		<meta name="viewport" content="width=device-width" />
+		<link rel="icon" type="image/svg+xml" href="/favicon.svg" />
+		<meta name="generator" content={Astro.generator} />
+		<title>{title}</title>
+		<style is:global>
+			@import "../styles/global.css";
+		</style>
+	</head>
+	<body>
+		<slot />
+	</body>
+</html>
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/src/pages/DirectContentUsage.astro b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/pages/DirectContentUsage.astro
new file mode 100644
index 000000000..cbf4295a7
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/pages/DirectContentUsage.astro
@@ -0,0 +1,17 @@
+---
+import UsingMdx from '../components/UsingMdx.astro'
+---
+
+<html lang="en">
+	<head>
+		<meta charset="utf-8" />
+		<link rel="icon" type="image/svg+xml" href="/favicon.svg" />
+		<meta name="viewport" content="width=device-width" />
+		<meta name="generator" content={Astro.generator} />
+		<title>Astro</title>
+	</head>
+	<body>
+		<h1>Astro</h1>
+		<UsingMdx />
+	</body>
+</html>
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/src/pages/posts/[post].astro b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/pages/posts/[post].astro
new file mode 100644
index 000000000..7d6ca0ca4
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/pages/posts/[post].astro
@@ -0,0 +1,18 @@
+---
+import { getCollection } from 'astro:content';
+import Layout from '../../layouts/ContentLayout.astro';
+import SmallCaps from '../../components/SmallCaps.astro';
+
+export async function getStaticPaths() {
+  const entries = await getCollection('posts');
+  return entries.map(entry => {
+    return {params: { post: entry.slug }, props: { entry },
+  }});
+}
+
+const { entry } = Astro.props;
+const { Content } = await entry.render();
+---
+<Layout title="">
+  <Content components={{ SmallCaps }} />
+</Layout>
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/src/pages/remote.astro b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/pages/remote.astro
new file mode 100644
index 000000000..9a7b76a10
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/pages/remote.astro
@@ -0,0 +1,17 @@
+---
+import '../styles/global.css'
+import Layout from '../layouts/One.astro';
+import Paragraph from '../components/P.astro';
+import { Markdown } from 'astro-remote'
+---
+
+<Layout title="Welcome to Astro.">
+	<main>
+		<Markdown
+      components={{
+				p: Paragraph,
+      }}>
+			**Removing p component fixes the problem**
+			</Markdown>
+	</main>
+</Layout>
diff --git a/packages/integrations/mdx/test/fixtures/css-head-mdx/src/styles/global.css b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/styles/global.css
new file mode 100644
index 000000000..e1450526f
--- /dev/null
+++ b/packages/integrations/mdx/test/fixtures/css-head-mdx/src/styles/global.css
@@ -0,0 +1,3 @@
+html {
+	font-weight: bolder;
+}