diff --git a/.changeset/chilled-humans-roll.md b/.changeset/chilled-humans-roll.md
new file mode 100644
index 000000000000..14e779a03a54
--- /dev/null
+++ b/.changeset/chilled-humans-roll.md
@@ -0,0 +1,5 @@
+---
+"@sveltejs/kit": patch
+---
+
+fix: detect assets emitted by vite plugins in prerenderer `fetch`.
diff --git a/packages/kit/src/core/generate_manifest/index.js b/packages/kit/src/core/generate_manifest/index.js
index a2ef4cd4c619..2e63bc5c47a3 100644
--- a/packages/kit/src/core/generate_manifest/index.js
+++ b/packages/kit/src/core/generate_manifest/index.js
@@ -80,6 +80,15 @@ export function generate_manifest({ build_data, relative_path, routes }) {
mime_types[ext] ??= mime.lookup(ext) || '';
}
+ const emitted_asset_dir = path.resolve(build_data.out_dir, 'server', build_data.asset_prefix);
+ if (fs.existsSync(emitted_asset_dir)) {
+ for (const file of fs.readdirSync(emitted_asset_dir)) {
+ assets.push(path.join(build_data.asset_prefix, file).replaceAll(path.sep, '/'));
+ const ext = path.extname(file);
+ mime_types[ext] ??= mime.lookup(ext) || '';
+ }
+ }
+
// prettier-ignore
// String representation of
/** @template {import('@sveltejs/kit').SSRManifest} T */
diff --git a/packages/kit/src/core/postbuild/prerender.js b/packages/kit/src/core/postbuild/prerender.js
index 05c995ab9771..76394585a941 100644
--- a/packages/kit/src/core/postbuild/prerender.js
+++ b/packages/kit/src/core/postbuild/prerender.js
@@ -211,6 +211,11 @@ async function prerender({ out, manifest_path, metadata, verbose, env }) {
const filepath = saved.get(file);
if (filepath) return readFileSync(filepath);
+ // Static assets emitted during build
+ if (file.startsWith(config.appDir)) {
+ return readFileSync(join(config.outDir, 'output', 'server', file));
+ }
+
// stuff in `static`
return readFileSync(join(config.files.assets, file));
},
diff --git a/packages/kit/src/exports/vite/index.js b/packages/kit/src/exports/vite/index.js
index c91055ba9aa7..393171283d0b 100644
--- a/packages/kit/src/exports/vite/index.js
+++ b/packages/kit/src/exports/vite/index.js
@@ -754,6 +754,7 @@ async function kit({ svelte_config }) {
app_path: `${kit.paths.base.slice(1)}${kit.paths.base ? '/' : ''}${kit.appDir}`,
manifest_data,
out_dir: out,
+ asset_prefix: `${kit.appDir}/immutable/assets`,
service_worker: service_worker_entry_file ? 'service-worker.js' : null, // TODO make file configurable?
client: null,
server_manifest
diff --git a/packages/kit/src/types/internal.d.ts b/packages/kit/src/types/internal.d.ts
index af50cbe74c7d..38c6350c12c3 100644
--- a/packages/kit/src/types/internal.d.ts
+++ b/packages/kit/src/types/internal.d.ts
@@ -63,6 +63,7 @@ export interface BuildData {
app_path: string;
manifest_data: ManifestData;
out_dir: string;
+ asset_prefix: string;
service_worker: string | null;
client: {
start: string;
diff --git a/packages/kit/test/prerendering/paths-base/custom_asset_plugin.js b/packages/kit/test/prerendering/paths-base/custom_asset_plugin.js
new file mode 100644
index 000000000000..3a28d6c3cabe
--- /dev/null
+++ b/packages/kit/test/prerendering/paths-base/custom_asset_plugin.js
@@ -0,0 +1,41 @@
+import fs from 'node:fs';
+import path from 'node:path';
+
+export default function () {
+ let config;
+ const ext = '.csv';
+ return {
+ name: 'vite-plugin-sveltekit-custom-asset',
+ resolveId(id) {
+ if (id.endsWith(ext)) {
+ return id;
+ }
+ },
+ configResolved(resolvedConfig) {
+ config = resolvedConfig;
+ },
+ load(id) {
+ if (!id.endsWith(ext)) return;
+ if (config.command === 'serve')
+ return `export default "${path.relative(process.cwd(), id).replaceAll(path.sep, '/')}";`;
+
+ const outName = config.build.rollupOptions.output.assetFileNames
+ .replace('[name]', path.basename(id, ext))
+ .replace('[hash]', '000000')
+ .replace('[extname]', ext);
+
+ if (config.build?.ssr) {
+ const ref = this.emitFile({
+ type: 'asset',
+ fileName: outName
+ });
+ fs.readFile(id, (err, data) => {
+ if (err) this.error(err);
+ this.setAssetSource(ref, data);
+ });
+ }
+
+ return `export default "${config.base}${outName}";`;
+ }
+ };
+}
diff --git a/packages/kit/test/prerendering/paths-base/src/routes/assets/emitted/+page.js b/packages/kit/test/prerendering/paths-base/src/routes/assets/emitted/+page.js
new file mode 100644
index 000000000000..ecd0785e6b06
--- /dev/null
+++ b/packages/kit/test/prerendering/paths-base/src/routes/assets/emitted/+page.js
@@ -0,0 +1,8 @@
+// @ts-ignore
+import url from './message.csv';
+
+export async function load({ fetch }) {
+ const response = await fetch(url);
+ const asset = await response.text();
+ return { asset };
+}
diff --git a/packages/kit/test/prerendering/paths-base/src/routes/assets/emitted/+page.svelte b/packages/kit/test/prerendering/paths-base/src/routes/assets/emitted/+page.svelte
new file mode 100644
index 000000000000..33b39b7e03cd
--- /dev/null
+++ b/packages/kit/test/prerendering/paths-base/src/routes/assets/emitted/+page.svelte
@@ -0,0 +1,5 @@
+
+
+{data.asset}
diff --git a/packages/kit/test/prerendering/paths-base/src/routes/assets/emitted/message.csv b/packages/kit/test/prerendering/paths-base/src/routes/assets/emitted/message.csv
new file mode 100644
index 000000000000..07beee08078d
--- /dev/null
+++ b/packages/kit/test/prerendering/paths-base/src/routes/assets/emitted/message.csv
@@ -0,0 +1 @@
+A custom asset emitted by a vite plugin during build.
\ No newline at end of file
diff --git a/packages/kit/test/prerendering/paths-base/test/tests.spec.js b/packages/kit/test/prerendering/paths-base/test/tests.spec.js
index 77674df89c93..1ea39a737327 100644
--- a/packages/kit/test/prerendering/paths-base/test/tests.spec.js
+++ b/packages/kit/test/prerendering/paths-base/test/tests.spec.js
@@ -29,3 +29,8 @@ test('prerenders /path-base/assets', () => {
const content = read('assets.html');
assert.match(content, /]+src="\/path-base\//u);
});
+
+test('prerenders /path-base/assets/emitted', () => {
+ const content = read('assets/emitted.html');
+ assert.ok(content.includes('A custom asset emitted by a vite plugin during build.
'));
+});
diff --git a/packages/kit/test/prerendering/paths-base/vite.config.js b/packages/kit/test/prerendering/paths-base/vite.config.js
index 2857b2592d11..cd49ec622d63 100644
--- a/packages/kit/test/prerendering/paths-base/vite.config.js
+++ b/packages/kit/test/prerendering/paths-base/vite.config.js
@@ -1,5 +1,6 @@
import * as path from 'node:path';
import { sveltekit } from '@sveltejs/kit/vite';
+import csvasset from './custom_asset_plugin.js';
/** @type {import('vite').UserConfig} */
const config = {
@@ -13,7 +14,7 @@ const config = {
logLevel: 'silent',
- plugins: [sveltekit()],
+ plugins: [csvasset(), sveltekit()],
server: {
fs: {
diff --git a/packages/kit/types/index.d.ts b/packages/kit/types/index.d.ts
index 1219176d5665..bb2a23166a95 100644
--- a/packages/kit/types/index.d.ts
+++ b/packages/kit/types/index.d.ts
@@ -1587,6 +1587,7 @@ declare module '@sveltejs/kit' {
app_path: string;
manifest_data: ManifestData;
out_dir: string;
+ asset_prefix: string;
service_worker: string | null;
client: {
start: string;