Shrink notification and device list page sizes on phones

On phone-width layouts (< Breakpoints.medium) the notification and device
lists now request fewer items per page so the list and its pagination bar
fit on screen together on common current phones. Notifications use 4 items
and devices 6 on phones; wider layouts keep 5 and 10 respectively. The
initial fetch is deferred to didChangeDependencies so the page size can read
the screen width from MediaQuery.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/lib/devices/device_list.dart

@@ -17,7 +17,11 @@ import 'device_list_filter.dart';
 import 'device_list_rows.dart';
 import 'device_list_sort.dart';
 
-const _pageSize = 10;
+// Phones show fewer devices so the list and its pagination controls fit on
+// screen at once on the common current phones (e.g. iPhone 15, Pixel 8); the
+// wider table layout has the vertical room for a full page.
+const _phonePageSize = 6;
+const _widePageSize = 10;
 
 class DeviceList extends StatefulWidget {
   const DeviceList({super.key});
@@ -40,14 +44,18 @@ class _DeviceListState extends State<DeviceList> with RouteAware {
 
   int _currentPage = 0;
   bool _hasNextPage = false;
+  bool _didInitialFetch = false;
   CancelToken? _fetchToken;
   final ScrollController _scrollController = ScrollController();
 
+  int get _pageSize => MediaQuery.sizeOf(context).width < Breakpoints.medium
+      ? _phonePageSize
+      : _widePageSize;
+
   @override
   void initState() {
     super.initState();
     _ownerController.addListener(_onOwnerChanged);
-    _fetchPage(0);
   }
 
   @override
@@ -57,6 +65,12 @@ class _DeviceListState extends State<DeviceList> with RouteAware {
     if (route is ModalRoute<void>) {
       routeObserver.subscribe(this, route);
     }
+    // Deferred from initState so the page size can read the screen width from
+    // MediaQuery, which is only available once dependencies are in place.
+    if (!_didInitialFetch) {
+      _didInitialFetch = true;
+      _fetchPage(0);
+    }
   }
 
   @override

frontend/lib/home/notifications_list.dart

@@ -14,7 +14,11 @@ import '../widgets/pagination_bar.dart';
 import '../widgets/skeleton.dart';
 import 'notification_card.dart';
 
-const _pageSize = 5;
+// Phones show fewer notifications so the list and its pagination controls fit
+// on screen at once on the common current phones (e.g. iPhone 15, Pixel 8);
+// wider layouts have the vertical room for a couple more.
+const _phonePageSize = 4;
+const _widePageSize = 5;
 
 enum _NotificationFilter {
   newOnly('New'),
@@ -47,8 +51,13 @@ class _NotificationsListState extends State<NotificationsList>
   Timer? _notificationTimer;
 
   int _currentPage = 0;
+  bool _didInitialFetch = false;
   List<oott_model.Notification> _items = [];
   bool _isLoading = false;
+
+  int get _pageSize => MediaQuery.sizeOf(context).width < Breakpoints.medium
+      ? _phonePageSize
+      : _widePageSize;
   bool _hasNextPage = false;
   String? _error;
   CancelToken? _fetchToken;
@@ -58,7 +67,6 @@ class _NotificationsListState extends State<NotificationsList>
   void initState() {
     super.initState();
     WidgetsBinding.instance.addObserver(this);
-    _fetchPage(0);
     _startTimer();
   }
 
@@ -69,6 +77,12 @@ class _NotificationsListState extends State<NotificationsList>
     if (route is ModalRoute<void>) {
       routeObserver.subscribe(this, route);
     }
+    // Deferred from initState so the page size can read the screen width from
+    // MediaQuery, which is only available once dependencies are in place.
+    if (!_didInitialFetch) {
+      _didInitialFetch = true;
+      _fetchPage(0);
+    }
   }
 
   @override

frontend/test/widget/notifications_list_test.dart

@@ -62,19 +62,21 @@ void main() {
     tester.view.devicePixelRatio = 1.0;
     addTearDown(tester.view.resetPhysicalSize);
 
+    // The 400px-wide viewport above is a phone, so the list uses the smaller
+    // phone page size of 4 (requesting page_limit 5 to detect a next page).
     List<Map<String, dynamic>> page(int firstId) => List.generate(
-      6,
+      5,
       (i) => notificationJson(id: firstId + i, title: 'Item ${firstId + i}'),
     );
     adapter.onGet(
       '/notifications',
       (server) => server.reply(200, page(1)),
-      queryParameters: {'is_new': true, 'page_offset': 0, 'page_limit': 6},
+      queryParameters: {'is_new': true, 'page_offset': 0, 'page_limit': 5},
     );
     adapter.onGet(
       '/notifications',
-      (server) => server.reply(200, page(7)),
-      queryParameters: {'is_new': true, 'page_offset': 5, 'page_limit': 6},
+      (server) => server.reply(200, page(6)),
+      queryParameters: {'is_new': true, 'page_offset': 4, 'page_limit': 5},
     );
 
     await tester.pumpWidget(
@@ -119,7 +121,7 @@ void main() {
     adapter.onGet(
       '/notifications',
       (server) => server.reply(200, items),
-      queryParameters: {'is_new': true, 'page_offset': 0, 'page_limit': 6},
+      queryParameters: {'is_new': true, 'page_offset': 0, 'page_limit': 5},
     );
 
     await tester.pumpWidget(