feat: implement read

packages/adapter-node/src/handler.js

@@ -4,15 +4,20 @@ import path from 'node:path';
 import sirv from 'sirv';
 import { fileURLToPath } from 'node:url';
 import { parse as polka_url_parser } from '@polka/url';
-import { getRequest, setResponse } from '@sveltejs/kit/node';
+import { getRequest, setResponse, readFile } from '@sveltejs/kit/node';
 import { Server } from 'SERVER';
 import { manifest, prerendered } from 'MANIFEST';
 import { env } from 'ENV';
 
 /* global ENV_PREFIX */
 
 const server = new Server(manifest);
-await server.init({ env: process.env });
+
+await server.init({
+	env: process.env,
+	readAsset: (file) => readFile(path.join(dir, 'client', file))
+});
+
 const origin = env('ORIGIN', undefined);
 const xff_depth = parseInt(env('XFF_DEPTH', '1'));
 const address_header = env('ADDRESS_HEADER', '').toLowerCase();

packages/kit/scripts/generate-dts.js

@@ -13,6 +13,7 @@ await createBundle({
 		'$app/forms': 'src/runtime/app/forms.js',
 		'$app/navigation': 'src/runtime/app/navigation.js',
 		'$app/paths': 'src/runtime/app/paths/types.d.ts',
+		'$app/server': 'src/runtime/app/server/index.js',
 		'$app/stores': 'src/runtime/app/stores.js'
 	},
 	include: ['src']

packages/kit/src/core/sync/write_server.js

@@ -30,6 +30,7 @@ const server_template = ({
 import root from '../root.${isSvelte5Plus() ? 'js' : 'svelte'}';
 import { set_building, set_prerendering } from '__sveltekit/environment';
 import { set_assets } from '__sveltekit/paths';
+import { set_read_asset } from '__sveltekit/server';
 import { set_private_env, set_public_env, set_safe_public_env } from '${runtime_directory}/shared-server.js';
 
 export const options = {
@@ -68,7 +69,7 @@ export async function get_hooks() {
 	};
 }
 
-export { set_assets, set_building, set_prerendering, set_private_env, set_public_env, set_safe_public_env };
+export { set_assets, set_building, set_prerendering, set_private_env, set_public_env, set_read_asset, set_safe_public_env };
 `;
 
 // TODO need to re-run this whenever src/app.html or src/error.html are

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

@@ -1,3 +1,6 @@
+import fs from 'node:fs';
+import { Readable } from 'node:stream';
+import * as mime from 'mrmime';
 import * as set_cookie_parser from 'set-cookie-parser';
 import { SvelteKitError } from '../../runtime/control.js';
 
@@ -189,3 +192,22 @@ export async function setResponse(res, response) {
 		}
 	}
 }
+
+/**
+ * TODO
+ * @param {string} file
+ */
+export function readFile(file) {
+	const stats = fs.statSync(file);
+	const body = Readable.toWeb(fs.createReadStream(file));
+
+	// @ts-expect-error I think the types are wrong
+	const response = new Response(body, {
+		headers: {
+			'Content-Length': stats.size.toString(),
+			'Content-Type': mime.lookup(file) ?? 'application/octet-stream'
+		}
+	});
+
+	return response;
+}

packages/kit/src/exports/public.d.ts

@@ -1145,6 +1145,7 @@ export class Server {
 
 export interface ServerInitOptions {
 	env: Record<string, string>;
+	readAsset?: (file: string) => Response;
 }
 
 export interface SSRManifest {

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

@@ -4,7 +4,7 @@ import { URL } from 'node:url';
 import colors from 'kleur';
 import sirv from 'sirv';
 import { isCSSRequest, loadEnv, buildErrorMessage } from 'vite';
-import { getRequest, setResponse } from '../../../exports/node/index.js';
+import { getRequest, readFile, setResponse } from '../../../exports/node/index.js';
 import { installPolyfills } from '../../../exports/node/polyfills.js';
 import { coalesce_to_error } from '../../../utils/error.js';
 import { posixify, resolve_entry, to_fs } from '../../../utils/filesystem.js';
@@ -470,7 +470,10 @@ export async function dev(vite, vite_config, svelte_config) {
 
 				const server = new Server(manifest);
 
-				await server.init({ env });
+				await server.init({
+					env,
+					readAsset: (file) => readFile(`.${file}`)
+				});
 
 				const request = await getRequest({
 					base,

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

@@ -31,7 +31,8 @@ import {
 	env_static_public,
 	service_worker,
 	sveltekit_environment,
-	sveltekit_paths
+	sveltekit_paths,
+	sveltekit_server
 } from './module_ids.js';
 import { pathToFileURL } from 'node:url';
 
@@ -492,6 +493,16 @@ async function kit({ svelte_config }) {
 						}
 					`;
 				}
+
+				case sveltekit_server: {
+					return dedent`
+						export let read_asset = null;
+
+						export function set_read_asset(fn) {
+							read_asset = fn;
+						}
+					`;
+				}
 			}
 		}
 	};

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

@@ -2,6 +2,9 @@ export const env_static_private = '\0virtual:$env/static/private';
 export const env_static_public = '\0virtual:$env/static/public';
 export const env_dynamic_private = '\0virtual:$env/dynamic/private';
 export const env_dynamic_public = '\0virtual:$env/dynamic/public';
+
 export const service_worker = '\0virtual:$service-worker';
-export const sveltekit_paths = '\0virtual:__sveltekit/paths';
+
 export const sveltekit_environment = '\0virtual:__sveltekit/environment';
+export const sveltekit_paths = '\0virtual:__sveltekit/paths';
+export const sveltekit_server = '\0virtual:__sveltekit/server';

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

@@ -4,7 +4,7 @@ import { pathToFileURL } from 'node:url';
 import { lookup } from 'mrmime';
 import sirv from 'sirv';
 import { loadEnv, normalizePath } from 'vite';
-import { getRequest, setResponse } from '../../../exports/node/index.js';
+import { getRequest, readFile, setResponse } from '../../../exports/node/index.js';
 import { installPolyfills } from '../../../exports/node/polyfills.js';
 import { SVELTE_KIT_ASSETS } from '../../../constants.js';
 import { not_found } from '../utils.js';
@@ -47,7 +47,8 @@ export async function preview(vite, vite_config, svelte_config) {
 
 	const server = new Server(manifest);
 	await server.init({
-		env: loadEnv(vite_config.mode, svelte_config.kit.env.dir, '')
+		env: loadEnv(vite_config.mode, svelte_config.kit.env.dir, ''),
+		readAsset: (file) => readFile(dir + file)
 	});
 
 	return () => {

packages/kit/src/runtime/app/server/index.js

@@ -0,0 +1,32 @@
+import { read_asset } from '__sveltekit/server';
+
+/**
+ * TODO docs
+ * @param {string} file
+ * @returns {Response}
+ */
+export function readAsset(file) {
+	if (!read_asset) {
+		throw new Error(
+			'No readAsset implementation was provided. Please ensure that your adapter is up to date and supports this feature'
+		);
+	}
+
+	// handle inline assets internally
+	if (file.startsWith('data:')) {
+		const [prelude, data] = file.split(';');
+		const type = prelude.slice(5) || 'application/octet-stream';
+
+		const decoded = data.startsWith('base64,') ? atob(data.slice(7)) : decodeURIComponent(data);
+
+		return new Response(decoded, {
+			headers: {
+				'Content-Type': type,
+				'Content-Length': decoded.length.toString()
+			}
+		});
+	}
+
+	// for everything else, delegate to adapter
+	return read_asset(file);
+}

packages/kit/src/runtime/server/index.js

@@ -4,6 +4,7 @@ import { options, get_hooks } from '__SERVER__/internal.js';
 import { DEV } from 'esm-env';
 import { filter_private_env, filter_public_env } from '../../utils/env.js';
 import { prerendering } from '__sveltekit/environment';
+import { set_read_asset } from '__sveltekit/server';
 
 /** @type {ProxyHandler<{ type: 'public' | 'private' }>} */
 const prerender_env_handler = {
@@ -30,10 +31,11 @@ export class Server {
 
 	/**
 	 * @param {{
-	 *   env: Record<string, string>
+	 *   env: Record<string, string>;
+	 *   readAsset?: (file: string) => Response;
 	 * }} opts
 	 */
-	async init({ env }) {
+	async init({ env, readAsset }) {
 		// Take care: Some adapters may have to call `Server.init` per-request to set env vars,
 		// so anything that shouldn't be rerun should be wrapped in an `if` block to make sure it hasn't
 		// been done already.
@@ -55,6 +57,10 @@ export class Server {
 		);
 		set_safe_public_env(public_env);
 
+		if (readAsset) {
+			set_read_asset(readAsset);
+		}
+
 		if (!this.#options.hooks) {
 			try {
 				const module = await get_hooks();

packages/kit/src/types/ambient-private.d.ts

@@ -16,3 +16,9 @@ declare module '__sveltekit/paths' {
 	export function override(paths: { base: string; assets: string }): void;
 	export function set_assets(path: string): void;
 }
+
+/** Internal version of $app/server */
+declare module '__sveltekit/server' {
+	export function read_asset(path: string): Response;
+	export function set_read_asset(fn: (path: string) => Response): void;
+}

packages/kit/src/types/internal.d.ts

@@ -33,6 +33,7 @@ export interface ServerInternalModule {
 	set_prerendering(): void;
 	set_private_env(environment: Record<string, string>): void;
 	set_public_env(environment: Record<string, string>): void;
+	set_read_asset(implementation: (path: string) => Response): void;
 	set_safe_public_env(environment: Record<string, string>): void;
 	set_version(version: string): void;
 	set_fix_stack_trace(fix_stack_trace: (error: unknown) => string): void;

packages/kit/types/index.d.ts

@@ -1127,6 +1127,7 @@ declare module '@sveltejs/kit' {
 
 	export interface ServerInitOptions {
 		env: Record<string, string>;
+		readAsset?: (file: string) => Response;
 	}
 
 	export interface SSRManifest {
@@ -1873,6 +1874,10 @@ declare module '@sveltejs/kit/node' {
 	}): Promise<Request>;
 
 	export function setResponse(res: import('http').ServerResponse, response: Response): Promise<void>;
+	/**
+	 * TODO
+	 * */
+	export function readFile(file: string): Response;
 }
 
 declare module '@sveltejs/kit/node/polyfills' {
@@ -2107,6 +2112,13 @@ declare module '$app/paths' {
 	export function resolveRoute(id: string, params: Record<string, string | undefined>): string;
 }
 
+declare module '$app/server' {
+	/**
+	 * TODO docs
+	 * */
+	export function readAsset(file: string): Response;
+}
+
 declare module '$app/stores' {
 	export function getStores(): {