Make 'lit' always be bundled in SSR

.changeset/old-plants-glow.md

@@ -0,0 +1,6 @@
+---
+'astro': patch
+'@astrojs/lit': patch
+---
+
+Fixes lit when running in SSR

packages/astro/src/core/build/vite-plugin-pages.ts

@@ -40,7 +40,9 @@ export function vitePluginPages(opts: StaticBuildOptions, internals: BuildIntern
 				let rendererItems = '';
 				for (const renderer of opts.astroConfig._ctx.renderers) {
 					const variable = `_renderer${i}`;
-					imports.push(`import ${variable} from '${renderer.serverEntrypoint}';`);
+					// Use unshift so that renderers are imported before user code, in case they set globals
+					// that user code depends on.
+					imports.unshift(`import ${variable} from '${renderer.serverEntrypoint}';`);
 					rendererItems += `Object.assign(${JSON.stringify(renderer)}, { ssr: ${variable} }),`;
 					i++;
 				}

packages/astro/test/ssr-lit.test.js

@@ -27,6 +27,7 @@ describe('Lit integration in SSR', () => {
 	}
 
 	it('Is able to load', async () => {
+		delete globalThis.window;
 		const html = await fetchHTML('/');
 		const $ = cheerioLoad(html);
 		expect($('#win').text()).to.equal('function');

packages/integrations/lit/src/index.ts

@@ -1,5 +1,5 @@
 import { readFileSync } from 'node:fs';
-import type { AstroIntegration } from 'astro';
+import type { AstroConfig, AstroIntegration } from 'astro';
 
 function getViteConfiguration() {
 	return {
@@ -45,6 +45,19 @@ export default function (): AstroIntegration {
 					vite: getViteConfiguration(),
 				});
 			},
+			'astro:build:setup': ({ vite, target }) => {
+				if (target === 'server') {
+					if(!vite.ssr) {
+						vite.ssr = {};
+					}
+					if(!vite.ssr.noExternal) {
+						vite.ssr.noExternal = [];
+					}
+					if(Array.isArray(vite.ssr.noExternal)) {
+						vite.ssr.noExternal.push('lit')
+					}
+				}
+			},
 		},
 	};
 }