fix: handle relative assets paths in server fetch correctly

.changeset/dirty-rivers-tickle.md

@@ -0,0 +1,8 @@
+---
+"@sveltejs/adapter-cloudflare-workers": patch
+"@sveltejs/adapter-cloudflare": patch
+"@sveltejs/adapter-netlify": patch
+"@sveltejs/kit": patch
+---
+
+fix: correctly handle relative paths when fetching assets on the server

packages/adapter-cloudflare-workers/files/entry.js

@@ -57,7 +57,10 @@ export default {
 		const filename = stripped_pathname.substring(1);
 		if (filename) {
 			is_static_asset =
-				manifest.assets.has(filename) || manifest.assets.has(filename + '/index.html');
+				manifest.assets.has(filename) ||
+				manifest.assets.has(filename + '/index.html') ||
+				filename in manifest._.server_assets ||
+				filename + '/index.html' in manifest._.server_assets;
 		}
 
 		let location = pathname.at(-1) === '/' ? stripped_pathname : pathname + '/';

packages/adapter-cloudflare/src/worker.js

@@ -31,7 +31,10 @@ const worker = {
 		const filename = stripped_pathname.substring(1);
 		if (filename) {
 			is_static_asset =
-				manifest.assets.has(filename) || manifest.assets.has(filename + '/index.html');
+				manifest.assets.has(filename) ||
+				manifest.assets.has(filename + '/index.html') ||
+				filename in manifest._.server_assets ||
+				filename + '/index.html' in manifest._.server_assets;
 		}
 
 		let location = pathname.at(-1) === '/' ? stripped_pathname : pathname + '/';

packages/adapter-netlify/src/edge.js

@@ -54,6 +54,8 @@ function is_static_file(request) {
 	return (
 		manifest.assets.has(file) ||
 		manifest.assets.has(file + '/index.html') ||
+		file in manifest._.server_assets ||
+		file + '/index.html' in manifest._.server_assets ||
 		prerendered.has(pathname || '/')
 	);
 }

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

@@ -527,7 +527,13 @@ export async function dev(vite, vite_config, svelte_config) {
 						if (remoteAddress) return remoteAddress;
 						throw new Error('Could not determine clientAddress');
 					},
-					read: (file) => fs.readFileSync(path.join(svelte_config.kit.files.assets, file)),
+					read: (file) => {
+						if (file in manifest._.server_assets) {
+							return fs.readFileSync(from_fs(file));
+						}
+
+						return fs.readFileSync(path.join(svelte_config.kit.files.assets, file));
+					},
 					before_handle: (event, config, prerender) => {
 						async_local_storage.enterWith({ event, config, prerender });
 					},

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

@@ -193,7 +193,13 @@ export async function preview(vite, vite_config, svelte_config) {
 						if (remoteAddress) return remoteAddress;
 						throw new Error('Could not determine clientAddress');
 					},
-					read: (file) => fs.readFileSync(join(svelte_config.kit.files.assets, file)),
+					read: (file) => {
+						if (file in manifest._.server_assets) {
+							return fs.readFileSync(join(dir, file));
+						}
+
+						return fs.readFileSync(join(svelte_config.kit.files.assets, file));
+					},
 					emulator
 				})
 			);

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

@@ -1,6 +1,7 @@
 import * as set_cookie_parser from 'set-cookie-parser';
 import { respond } from './respond.js';
 import * as paths from '__sveltekit/paths';
+import { read_implementation } from '__sveltekit/server';
 
 /**
  * @param {{
@@ -81,8 +82,9 @@ export function create_fetch({ event, options, manifest, state, get_cookie_heade
 				).slice(1);
 				const filename_html = `${filename}/index.html`; // path may also match path/index.html
 
-				const is_asset = manifest.assets.has(filename);
-				const is_asset_html = manifest.assets.has(filename_html);
+				const is_asset = manifest.assets.has(filename) || filename in manifest._.server_assets;
+				const is_asset_html =
+					manifest.assets.has(filename_html) || filename_html in manifest._.server_assets;
 
 				if (is_asset || is_asset_html) {
 					const file = is_asset ? filename : filename_html;
@@ -95,6 +97,16 @@ export function create_fetch({ event, options, manifest, state, get_cookie_heade
 						return new Response(state.read(file), {
 							headers: type ? { 'content-type': type } : {}
 						});
+					} else if (read_implementation) {
+						const length = manifest._.server_assets[file];
+						const type = manifest.mimeTypes[file.slice(file.lastIndexOf('.'))];
+
+						return new Response(read_implementation(file), {
+							headers: {
+								'Content-Length': '' + length,
+								'Content-Type': type
+							}
+						});
 					}
 
 					return await fetch(request);

packages/kit/test/apps/basics/src/routes/endpoint-output/fetch-asset/absolute/+server.js

@@ -0,0 +1,14 @@
+import file_path from '../test.txt?url';
+
+/** @type {import('@sveltejs/kit').RequestHandler} */
+export async function GET({ url }) {
+	const absolute = new URL(file_path, url.origin);
+
+	const response = await fetch(absolute);
+
+	return new Response(response.body, {
+		headers: {
+			'Content-Type': response.headers.get('Content-Type')
+		}
+	});
+}

packages/kit/test/apps/basics/src/routes/endpoint-output/fetch-asset/relative/+server.js

@@ -0,0 +1,12 @@
+import file_path from '../test.txt?url';
+
+/** @type {import('@sveltejs/kit').RequestHandler} */
+export async function GET({ fetch }) {
+	const response = await fetch(file_path);
+
+	return new Response(response.body, {
+		headers: {
+			'Content-Type': response.headers.get('Content-Type')
+		}
+	});
+}

packages/kit/test/apps/basics/src/routes/endpoint-output/fetch-asset/test.txt

@@ -0,0 +1 @@
+Cos sie konczy, cos zaczyna

packages/kit/test/apps/basics/test/server.test.js

@@ -249,6 +249,20 @@ test.describe('Endpoints', () => {
 		expect(response.status()).toBe(200);
 		expect(await response.text()).toBe('catch-all');
 	});
+
+	test('can get assets using absolute path', async ({ request }) => {
+		const response = await request.get('/endpoint-output/fetch-asset/absolute');
+		expect(response.status()).toBe(200);
+		expect(response.headers()['content-type']).toBe('text/plain');
+		expect(await response.text()).toBe('Cos sie konczy, cos zaczyna');
+	});
+
+	test('can get assets using relative path', async ({ request }) => {
+		const response = await request.get('/endpoint-output/fetch-asset/relative');
+		expect(response.status()).toBe(200);
+		expect(response.headers()['content-type']).toBe('text/plain');
+		expect(await response.text()).toBe('Cos sie konczy, cos zaczyna');
+	});
 });
 
 test.describe('Errors', () => {