[breaking] make sveltekit() return a promise (#7994)

.changeset/fast-mails-run.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+[breaking] make `sveltekit()` return a promise of array of Vite plugins

packages/kit/src/exports/vite/index.js

@@ -59,9 +59,25 @@ const enforced_config = {
 	root: true
 };
 
-/** @return {import('vite').Plugin[]} */
-export function sveltekit() {
-	return [...svelte(), ...kit()];
+/** @return {Promise<import('vite').Plugin[]>} */
+export async function sveltekit() {
+	const svelte_config = await load_config();
+
+	/** @type {import('@sveltejs/vite-plugin-svelte').Options} */
+	const vite_plugin_svelte_options = {
+		configFile: false,
+		extensions: svelte_config.extensions,
+		preprocess: svelte_config.preprocess,
+		onwarn: svelte_config.onwarn,
+		compilerOptions: {
+			// @ts-expect-error SvelteKit requires hydratable true by default
+			hydratable: true,
+			...svelte_config.compilerOptions
+		},
+		...svelte_config.vitePlugin
+	};
+
+	return [...svelte(vite_plugin_svelte_options), ...kit({ svelte_config })];
 }
 
 /**
@@ -74,12 +90,10 @@ export function sveltekit() {
  * - https://rollupjs.org/guide/en/#build-hooks
  * - https://rollupjs.org/guide/en/#output-generation-hooks
  *
+ * @param {{ svelte_config: import('types').ValidatedConfig }} options
  * @return {import('vite').Plugin[]}
  */
-function kit() {
-	/** @type {import('types').ValidatedConfig} */
-	let svelte_config;
-
+function kit({ svelte_config }) {
 	/** @type {import('vite').ResolvedConfig} */
 	let vite_config;
 
@@ -193,7 +207,6 @@ function kit() {
 		 */
 		async config(config, config_env) {
 			vite_config_env = config_env;
-			svelte_config = await load_config();
 
 			env = get_env(svelte_config.kit.env, vite_config_env.mode);
 

packages/kit/types/ambient.d.ts

@@ -433,5 +433,5 @@ declare module '@sveltejs/kit/vite' {
 	/**
 	 * Returns the SvelteKit Vite plugins.
 	 */
-	export function sveltekit(): Plugin[];
+	export function sveltekit(): Promise<Plugin[]>;
 }