From aa84692df3f0de19021153ada69572335cff8547 Mon Sep 17 00:00:00 2001
From: Copilot <198982749+Copilot@users.noreply.github.com>
Date: Sun, 27 Sep 2026 09:50:52 +0200
Subject: [PATCH] Make `USE_NEW_DESIGN` deterministic by cache-busting
 `config.json` in design switcher (#858)

* Initial plan

* Fix design switch config caching for USE_NEW_DESIGN

Co-authored-by: sstidl <12804296+sstidl@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: sstidl <12804296+sstidl@users.noreply.github.com>
---
 design-switch.js                |  3 ++-
 tests/e2e/design-switch.spec.js | 17 +++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/design-switch.js b/design-switch.js
index 0a23475..4ea78c6 100644
--- a/design-switch.js
+++ b/design-switch.js
@@ -37,7 +37,8 @@
     try {
         const xhr = new XMLHttpRequest();
         // Use a synchronous request to prevent a flash of the old design before redirecting
-        xhr.open('GET', 'config.json', false);
+        // Bypass stale browser caches so Docker env changes are reflected immediately
+        xhr.open('GET', 'config.json?_=' + Date.now(), false);
         xhr.send(null);
 
         // Check for a successful response, but not 304 Not Modified, which can have an empty response body
diff --git a/tests/e2e/design-switch.spec.js b/tests/e2e/design-switch.spec.js
index c676215..8cb1ac8 100644
--- a/tests/e2e/design-switch.spec.js
+++ b/tests/e2e/design-switch.spec.js
@@ -26,4 +26,21 @@ test.describe('Design switch behavior', () => {
     await expect(page).toHaveURL(/index-classic\.html\?design=old/);
     await expect(classicStartButton(page)).toBeVisible();
   });
+
+  test('config fetch bypasses browser cache', async ({ page }) => {
+    let configRequestUrl = '';
+
+    await page.route('**/config.json*', async (route) => {
+      configRequestUrl = route.request().url();
+      await route.fulfill({
+        status: 200,
+        contentType: 'application/json',
+        body: JSON.stringify({ useNewDesign: true }),
+      });
+    });
+
+    await page.goto(`${baseUrls.standalone}/index.html`);
+    await expect(page).toHaveURL(/index-modern\.html/);
+    expect(configRequestUrl).toMatch(/config\.json\?_=\d+/);
+  });
 });