diff --git a/package.json b/package.json
index d314a2b..5f755b4 100644
--- a/package.json
+++ b/package.json
@@ -9,7 +9,7 @@
   },
   "scripts": {
     "start": "vite",
-    "build": "vite build",
+    "build": "node ../scripts/generate-update-manifest.mjs && vite build",
     "lint": "yarn check:eslint && yarn check:prettier",
     "check:eslint": "eslint src/*",
     "check:prettier": "prettier --check .",
diff --git a/src/app/components/updates-dialog/UpdatesDialog.css.ts b/src/app/components/updates-dialog/UpdatesDialog.css.ts
index cc86776..af1f358 100644
--- a/src/app/components/updates-dialog/UpdatesDialog.css.ts
+++ b/src/app/components/updates-dialog/UpdatesDialog.css.ts
@@ -3,7 +3,13 @@ import { color, config, toRem } from 'folds';
 
 const MOBILE_BREAKPOINT = '480px';
 
-/** Dialog height cap — 85% of the viewport, minus safe areas. */
+export const PortalLayer = style({
+  position: 'fixed',
+  inset: 0,
+  zIndex: config.zIndex.Max,
+});
+
+/** Dialog + overlay padding must never exceed the viewport height. */
 const DIALOG_MAX_HEIGHT =
   'calc(85vh - env(safe-area-inset-top, 0px) - env(safe-area-inset-bottom, 0px))';
 
diff --git a/src/app/components/updates-dialog/UpdatesDialog.tsx b/src/app/components/updates-dialog/UpdatesDialog.tsx
index 202fda9..873363c 100644
--- a/src/app/components/updates-dialog/UpdatesDialog.tsx
+++ b/src/app/components/updates-dialog/UpdatesDialog.tsx
@@ -1,8 +1,10 @@
 import React, { useState } from 'react';
+import { createPortal } from 'react-dom';
 import FocusTrap from 'focus-trap-react';
 import {
   Box,
   Button,
+  config,
   Dialog,
   IconButton,
   Overlay,
@@ -46,18 +48,19 @@ export function UpdatesDialog({
     setShowOlderList(false);
   };
 
-  return (
-    <Overlay open backdrop={<OverlayBackdrop />}>
-      <OverlayCenter className={css.OverlayFrame}>
-        <FocusTrap
-          focusTrapOptions={{
-            initialFocus: false,
-            onDeactivate: onClose,
-            clickOutsideDeactivates: true,
-            escapeDeactivates: stopPropagation,
-          }}
-        >
-          <Dialog variant="Surface" className={css.DialogShell}>
+  return createPortal(
+    <div className={css.PortalLayer}>
+      <Overlay open backdrop={<OverlayBackdrop />}>
+        <OverlayCenter className={css.OverlayFrame}>
+          <FocusTrap
+            focusTrapOptions={{
+              initialFocus: false,
+              onDeactivate: onClose,
+              clickOutsideDeactivates: true,
+              escapeDeactivates: stopPropagation,
+            }}
+          >
+            <Dialog variant="Surface" className={css.DialogShell}>
             <Box className={css.Hero}>
               <Box className={css.HeroRow}>
                 <img className={css.HeroLogo} src={PaarrotSVG} alt="" draggable={false} />
@@ -177,5 +180,7 @@ export function UpdatesDialog({
         </FocusTrap>
       </OverlayCenter>
     </Overlay>
+    </div>,
+    document.body
   );
 }
diff --git a/src/app/data/updateNotes.ts b/src/app/data/updateNotes.ts
index 9add859..497ab41 100644
--- a/src/app/data/updateNotes.ts
+++ b/src/app/data/updateNotes.ts
@@ -1,6 +1,15 @@
 import { trimTrailingSlash } from '../utils/common';
 
-const UPDATE_BASE_PATH = `${trimTrailingSlash(import.meta.env.BASE_URL)}/update`;
+function getUpdateBaseUrl(): string {
+  const basePath = trimTrailingSlash(import.meta.env.BASE_URL || './');
+  const relative =
+    basePath === '.' || basePath === '' ? 'update/' : `${basePath}/update/`;
+  return new URL(relative, window.location.href).href.replace(/\/$/, '');
+}
+
+function getUpdateFileUrl(file: string): string {
+  return new URL(file, `${getUpdateBaseUrl()}/`).href;
+}
 
 export type UpdateManifestEntry = {
   file: string;
@@ -61,12 +70,12 @@ export function resolveUpdateAssetUrl(src: string | undefined): string | undefin
   if (src.startsWith('/')) return src;
 
   const normalized = src.replace(/^\.\//, '');
-  return `${UPDATE_BASE_PATH}/${normalized}`;
+  return new URL(normalized, `${getUpdateBaseUrl()}/`).href;
 }
 
 export async function loadUpdateManifest(): Promise<UpdateManifest | null> {
   try {
-    const response = await fetch(`${UPDATE_BASE_PATH}/manifest.json`, { cache: 'no-cache' });
+    const response = await fetch(getUpdateFileUrl('manifest.json'), { cache: 'no-cache' });
     if (!response.ok) return null;
 
     const data = (await response.json()) as UpdateManifest;
@@ -86,7 +95,7 @@ export async function loadUpdateDocument(file: string): Promise<ParsedUpdateDoc
   if (!safeFile || safeFile.includes('..')) return null;
 
   try {
-    const response = await fetch(`${UPDATE_BASE_PATH}/${safeFile}`, { cache: 'no-cache' });
+    const response = await fetch(getUpdateFileUrl(safeFile), { cache: 'no-cache' });
     if (!response.ok) return null;
 
     const source = await response.text();
diff --git a/src/app/pages/client/ClientNonUIFeatures.tsx b/src/app/pages/client/ClientNonUIFeatures.tsx
index 05a7a0b..1c3a268 100644
--- a/src/app/pages/client/ClientNonUIFeatures.tsx
+++ b/src/app/pages/client/ClientNonUIFeatures.tsx
@@ -699,10 +699,10 @@ export function ClientNonUIFeatures({ children }: ClientNonUIFeaturesProps) {
       <MessageNotifications />
       <BackgroundSyncSetup />
       <PaarrotAPIInitializer />
-      <UpdatesDialogHost />
       <TaskbarFlashStopper />
       <AndroidShareIntentHandler />
       {children}
+      <UpdatesDialogHost />
     </>
   );
 }