Fix markdown page HMR (#8418)

Co-authored-by: Nate Moore <natemoo-re@users.noreply.github.com>

Author: bluwy

.changeset/twelve-cars-tell.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fix markdown page HMR

packages/astro/src/vite-plugin-markdown/index.ts

@@ -107,7 +107,7 @@ export default function markdown({ settings, logger }: AstroPluginOptions): Plug
 				}
 
 				const code = escapeViteEnvReferences(`
-				import { unescapeHTML, spreadAttributes, createComponent, render, renderComponent } from ${JSON.stringify(
+				import { unescapeHTML, spreadAttributes, createComponent, render, renderComponent, maybeRenderHead } from ${JSON.stringify(
 					astroServerRuntimeModulePath
 				)};
 				import { AstroError, AstroErrorData } from ${JSON.stringify(astroErrorModulePath)};
@@ -180,10 +180,9 @@ export default function markdown({ settings, logger }: AstroPluginOptions): Plug
 							}, {
 								'default': () => render\`\${unescapeHTML(html)}\`
 							})}\`;`
-							: `render\`\${unescapeHTML(html)}\`;`
+							: `render\`\${maybeRenderHead(result)}\${unescapeHTML(html)}\`;`
 					}
 				});
-				Content[Symbol.for('astro.needsHeadRendering')] = ${layout ? 'false' : 'true'};
 				export default Content;
 				`);
 

packages/astro/test/astro-pages.test.js

@@ -49,5 +49,10 @@ describe('Pages', () => {
 
 			expect($('#testing').length).to.be.greaterThan(0);
 		});
+
+		it('should have Vite client in dev', async () => {
+			const html = await fixture.fetch('/').then((res) => res.text());
+			expect(html).to.include('/@vite/client', 'Markdown page does not have Vite client for HMR');
+		});
 	});
 });