From f36f6aeee141de58366025c550c11fe29f407d78 Mon Sep 17 00:00:00 2001
From: Jonathan Sykes <telemagnadon@gmail.com>
Date: Thu, 2 Jul 2026 13:40:36 +0800
Subject: [PATCH] fix: only treat a waiting service worker as an update when a
 controller exists

---
 frontend/app.js | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/frontend/app.js b/frontend/app.js
index 27ac065..362112e 100755
--- a/frontend/app.js
+++ b/frontend/app.js
@@ -3021,16 +3021,25 @@ async function registerServiceWorker() {
     const reg = await navigator.serviceWorker.register('/sw.js', { updateViaCache: 'none' });
     _swReg = reg;
 
+    // A waiting worker only means "update pending" when this page is already
+    // controlled by a previous SW. On a FIRST install (fresh visit, or right
+    // after Settings → Force refresh unregisters everything) the brand-new
+    // worker passes through the `installed`/waiting state for a moment before
+    // activating — with no controller that is not an update, and showing the
+    // banner for it is exactly the "Update available keeps coming back after
+    // Refresh UI" loop.
+    const hasController = () => !!navigator.serviceWorker.controller;
+
     // If a new SW is already waiting (e.g. user refreshed after an update),
     // show the dialog right away.
-    if (reg.waiting) { showUpdateBanner(); return; }
+    if (reg.waiting && hasController()) { showUpdateBanner(); return; }
 
     // Listen for a new SW installing after the page is open.
     reg.addEventListener('updatefound', () => {
       const sw = reg.installing;
       if (!sw) return;
       sw.addEventListener('statechange', () => {
-        if (sw.state === 'installed' && reg.waiting) showUpdateBanner();
+        if (sw.state === 'installed' && reg.waiting && hasController()) showUpdateBanner();
       });
     });