From 9dc5c0e3e01a3c07010e9996688169be68e1dde8 Mon Sep 17 00:00:00 2001
From: Torsten Dittmann <torsten.dittmann@googlemail.com>
Date: Wed, 15 Jan 2025 17:04:03 +0100
Subject: [PATCH] fix: service worker base path in dev mode (#12577)

Fixes #12039
---
 .changeset/nice-geese-serve.md                |  5 +++++
 packages/kit/src/exports/vite/dev/index.js    |  2 +-
 packages/kit/test/apps/options-2/test/test.js | 15 ++++++++++++++-
 3 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/nice-geese-serve.md

diff --git a/.changeset/nice-geese-serve.md b/.changeset/nice-geese-serve.md
new file mode 100644
index 000000000000..406180bebe27
--- /dev/null
+++ b/.changeset/nice-geese-serve.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: service worker base path in dev mode
diff --git a/packages/kit/src/exports/vite/dev/index.js b/packages/kit/src/exports/vite/dev/index.js
index 3935daf28565..bca3f84160cb 100644
--- a/packages/kit/src/exports/vite/dev/index.js
+++ b/packages/kit/src/exports/vite/dev/index.js
@@ -462,7 +462,7 @@ export async function dev(vite, vite_config, svelte_config) {
 						res.writeHead(200, {
 							'content-type': 'application/javascript'
 						});
-						res.end(`import '${to_fs(resolved)}';`);
+						res.end(`import '${svelte_config.kit.paths.base}${to_fs(resolved)}';`);
 					} else {
 						res.writeHead(404);
 						res.end('not found');
diff --git a/packages/kit/test/apps/options-2/test/test.js b/packages/kit/test/apps/options-2/test/test.js
index 1c5c0ffd525a..ba5f10003284 100644
--- a/packages/kit/test/apps/options-2/test/test.js
+++ b/packages/kit/test/apps/options-2/test/test.js
@@ -1,4 +1,6 @@
+import path from 'node:path';
 import process from 'node:process';
+import { fileURLToPath } from 'node:url';
 import { expect } from '@playwright/test';
 import { test } from '../../../utils.js';
 
@@ -73,7 +75,18 @@ test.describe('trailing slash', () => {
 });
 
 test.describe('Service worker', () => {
-	if (process.env.DEV) return;
+	if (process.env.DEV) {
+		test('import proxy /basepath/service-worker.js', async ({ request }) => {
+			const __dirname = path.dirname(fileURLToPath(import.meta.url));
+			const response = await request.get('/basepath/service-worker.js');
+			const content = await response.text();
+			expect(content).toEqual(
+				`import '${path.join('/basepath', '/@fs', __dirname, '../src/service-worker.js')}';`
+			);
+		});
+
+		return;
+	}
 
 	test('build /basepath/service-worker.js', async ({ baseURL, request }) => {
 		const response = await request.get('/basepath/service-worker.js');