always include <link rel="stylesheet"> even if excluded from Link headers - closes #8238 (#9255)

Author: Rich-Harris

.changeset/tall-impalas-report.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: always include `<link rel="stylesheet">`, even for stylesheets excluded from Link headers

packages/kit/src/runtime/server/page/render.js

@@ -235,20 +235,20 @@ export async function render_response({
 	for (const dep of stylesheets) {
 		const path = prefixed(dep);
 
-		if (resolve_opts.preload({ type: 'css', path })) {
-			const attributes = ['rel="stylesheet"'];
-
-			if (inline_styles.has(dep)) {
-				// don't load stylesheets that are already inlined
-				// include them in disabled state so that Vite can detect them and doesn't try to add them
-				attributes.push('disabled', 'media="(max-width: 0)"');
-			} else {
+		const attributes = ['rel="stylesheet"'];
+
+		if (inline_styles.has(dep)) {
+			// don't load stylesheets that are already inlined
+			// include them in disabled state so that Vite can detect them and doesn't try to add them
+			attributes.push('disabled', 'media="(max-width: 0)"');
+		} else {
+			if (resolve_opts.preload({ type: 'css', path })) {
 				const preload_atts = ['rel="preload"', 'as="style"'];
 				link_header_preloads.add(`<${encodeURI(path)}>; ${preload_atts.join(';')}; nopush`);
 			}
-
-			head += `\n\t\t<link href="${path}" ${attributes.join(' ')}>`;
 		}
+
+		head += `\n\t\t<link href="${path}" ${attributes.join(' ')}>`;
 	}
 
 	for (const dep of fonts) {

packages/kit/test/apps/options/source/hooks.server.js

@@ -0,0 +1,8 @@
+/** @type {import('@sveltejs/kit').Handle} */
+export function handle({ event, resolve }) {
+	return resolve(event, {
+		// this allows us to check that <link rel="stylesheet"> is still added
+		// to the DOM even if they're not included by `preload`
+		preload: ({ type }) => type !== 'css'
+	});
+}