web: the offer to install is made once, and the answer is kept

docker/frontend/src/ui/InstallPrompt.tsx

@@ -5,8 +5,8 @@ import {
   canInstall,
   dismissInstall,
   dismissed,
+  isInstalled,
   isIosSafari,
-  isStandalone,
   promptInstall,
   subscribe,
 } from '../pwa/install';
@@ -30,7 +30,7 @@ export function InstallPrompt() {
   useEffect(() => {
     // An installed app has nothing to offer, and a refusal is final — the visitor
     // said no to this dialog, not to this session.
-    if (isStandalone() || dismissed()) return;
+    if (isInstalled() || dismissed()) return;
 
     const manual = isIosSafari();
     let waited = false;
@@ -86,8 +86,8 @@ export function InstallPrompt() {
             type="button"
             className="btn primary"
             data-key="install-yes"
-            // Not a dismissal: taking the offer and waving the browser's own sheet
-            // away are different answers, and the app's own button can still ask.
+            // `promptInstall` records the browser's answer itself: accepted means the
+            // app is installed, waved away means the offer was spent and refused.
             onClick={() => {
               void promptInstall();
               setFace(null);