diff --git a/containers/libreportal/frontend/index.html b/containers/libreportal/frontend/index.html
index 6113cf0..65172ac 100755
--- a/containers/libreportal/frontend/index.html
+++ b/containers/libreportal/frontend/index.html
@@ -86,6 +86,7 @@
   <script src="/js/utils/ui-helpers.js"></script>
   <script src="/js/utils/router.js"></script>
   <script src="/js/utils/data-loader.js"></script>
+  <script src="/js/utils/dismissible.js"></script>
   <script src="/js/components/eo-modal.js"></script>
   <script src="/js/components/dashboard.js"></script>
   <script src="/js/system/system-loader.js"></script>
diff --git a/containers/libreportal/frontend/js/components/backup/backup-page.js b/containers/libreportal/frontend/js/components/backup/backup-page.js
index 7eff02b..7e89d6b 100644
--- a/containers/libreportal/frontend/js/components/backup/backup-page.js
+++ b/containers/libreportal/frontend/js/components/backup/backup-page.js
@@ -94,6 +94,7 @@ class BackupPage {
         this.applyActiveTabUi(this.currentTab);
         this.bindEvents();
         await this.refreshAll();
+        await window.Dismissible?.load();
         this.render();
         this.updatePageHeader();
         this.updatePrimaryAction();
@@ -213,7 +214,7 @@ class BackupPage {
 
             const dismissWarn = e.target.closest('[data-action="dismiss-config-warning"]');
             if (dismissWarn) {
-                localStorage.setItem('libreportal:backup-config-warning-dismissed', '1');
+                window.Dismissible?.dismiss('backup-config-warning');
                 const banner = dismissWarn.closest('.backup-warning-banner');
                 const divider = banner?.nextElementSibling;
                 if (divider && divider.classList.contains('config-divider')) divider.remove();
@@ -830,10 +831,10 @@ class BackupPage {
         const body = document.getElementById('backup-configuration-body');
         if (!body) return;
 
-        // The warning is a dismissible nudge, so its dismissed state lives in
-        // localStorage (per-browser) rather than server config. Banner + its
-        // divider are omitted entirely once dismissed.
-        const warningDismissed = localStorage.getItem('libreportal:backup-config-warning-dismissed') === '1';
+        // Dismissed state is persisted server-side via Dismissible
+        // (data/ui-state.json), so it follows the user across browsers/devices.
+        // Banner + its divider are omitted entirely once dismissed.
+        const warningDismissed = !!window.Dismissible?.isDismissed('backup-config-warning');
         const warningHTML = warningDismissed ? '' : `
             <div class="backup-warning-banner">
                 <svg class="backup-warning-banner-icon" width="32" height="32" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
diff --git a/containers/libreportal/frontend/js/utils/dismissible.js b/containers/libreportal/frontend/js/utils/dismissible.js
new file mode 100644
index 0000000..4a89aaa
--- /dev/null
+++ b/containers/libreportal/frontend/js/utils/dismissible.js
@@ -0,0 +1,67 @@
+// Dismissible — reusable "hide this UI element permanently" store.
+//
+// State is persisted server-side in data/ui-state.json via the authenticated
+// /read-file + /write-file endpoints, so a dismissal follows the user across
+// browsers and devices. It is a direct file read/write: no task is created
+// (nothing appears in the task manager) and no system scan runs.
+//
+// Usage:
+//   await Dismissible.load();              // once, before reading state (e.g. in a page init)
+//   if (!Dismissible.isDismissed('my-id')) { ...render the thing... }
+//   Dismissible.dismiss('my-id');          // on close — persists, fire-and-forget
+//   Dismissible.restore('my-id');          // bring it back
+window.Dismissible = (() => {
+  const FILE = 'ui-state.json';
+  let dismissed = new Set();
+  let loaded = false;
+
+  async function load() {
+    if (loaded) return;
+    try {
+      const res = await fetch(`/read-file?path=${encodeURIComponent(FILE)}`);
+      if (res.ok) {
+        const data = JSON.parse(await res.text());
+        if (Array.isArray(data?.dismissed)) dismissed = new Set(data.dismissed);
+      }
+      // A 404 just means nothing has been dismissed yet — leave the set empty.
+    } catch (_) {
+      // On any error, fail open: treat nothing as dismissed so notices still show.
+    }
+    loaded = true;
+  }
+
+  function isDismissed(id) {
+    return dismissed.has(id);
+  }
+
+  async function dismiss(id) {
+    await load();
+    if (dismissed.has(id)) return;
+    dismissed.add(id);
+    await persist();
+  }
+
+  async function restore(id) {
+    await load();
+    if (!dismissed.has(id)) return;
+    dismissed.delete(id);
+    await persist();
+  }
+
+  async function persist() {
+    try {
+      await fetch('/write-file', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({
+          path: FILE,
+          content: JSON.stringify({ dismissed: [...dismissed] }, null, 2)
+        })
+      });
+    } catch (err) {
+      console.warn('Dismissible: failed to persist state', err);
+    }
+  }
+
+  return { load, isDismissed, dismiss, restore };
+})();