refactor: share low-risk UI and tracker helpers

lib/utils/json_utils.dart

@@ -18,6 +18,15 @@ bool flexibleBool(Object? v) => switch (v) {
   _ => false,
 };
 
+/// Parse a value that may be [bool], [int] (0/1), or [String] ('1') to [bool].
+/// Returns `null` for `null` or unrecognised values.
+bool? flexibleBoolNullable(Object? v) => switch (v) {
+  final bool b => b,
+  final int n => n == 1,
+  final String s => s == '1',
+  _ => null,
+};
+
 /// Parse a value that may be [double], [num], or [String] to [double].
 double? flexibleDouble(Object? v) => switch (v) {
   final num n => n.toDouble(),

lib/utils/scroll_utils.dart

@@ -35,6 +35,21 @@ void scrollToCurrentItem(ScrollController controller, GlobalKey firstItemKey, in
   });
 }
 
+/// Owns the boilerplate for one-time initial scrolling in selectable lists.
+class InitialItemScrollController {
+  final GlobalKey firstItemKey = GlobalKey();
+  final ScrollController controller = ScrollController();
+  bool _didInitialScroll = false;
+
+  void maybeScrollTo(int? selectedIndex) {
+    if (_didInitialScroll || selectedIndex == null || selectedIndex <= 0) return;
+    _didInitialScroll = true;
+    scrollToCurrentItem(controller, firstItemKey, selectedIndex);
+  }
+
+  void dispose() => controller.dispose();
+}
+
 /// Scroll a horizontal list to center the item at the given index.
 ///
 /// Assumes items are laid out with [leadingPadding] before the first item,

lib/utils/update_dialog.dart

@@ -0,0 +1,63 @@
+import 'package:flutter/material.dart';
+import 'package:url_launcher/url_launcher.dart';
+
+import '../i18n/strings.g.dart';
+import '../services/update_service.dart';
+import '../widgets/dialog_action_button.dart';
+
+Future<void> showUpdateAvailableDialog(
+  BuildContext context,
+  Map<String, dynamic> updateInfo, {
+  required String title,
+  required String dismissLabel,
+  bool showSkipVersion = false,
+}) {
+  return showDialog<void>(
+    context: context,
+    builder: (dialogContext) {
+      final latestVersion = updateInfo['latestVersion'] as String;
+      final releaseUrl = updateInfo['releaseUrl'] as String;
+
+      return AlertDialog(
+        title: Text(title),
+        content: Column(
+          mainAxisSize: MainAxisSize.min,
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Text(
+              t.update.versionAvailable(version: latestVersion),
+              style: Theme.of(dialogContext).textTheme.titleMedium,
+            ),
+            const SizedBox(height: 8),
+            Text(
+              t.update.currentVersion(version: updateInfo['currentVersion']),
+              style: Theme.of(dialogContext).textTheme.bodySmall,
+            ),
+          ],
+        ),
+        actions: [
+          DialogActionButton(onPressed: () => Navigator.pop(dialogContext), label: dismissLabel),
+          if (showSkipVersion)
+            DialogActionButton(
+              onPressed: () async {
+                await UpdateService.skipVersion(latestVersion);
+                if (dialogContext.mounted) Navigator.pop(dialogContext);
+              },
+              label: t.update.skipVersion,
+            ),
+          DialogActionButton(
+            onPressed: () async {
+              final url = Uri.parse(releaseUrl);
+              if (await canLaunchUrl(url)) {
+                await launchUrl(url, mode: LaunchMode.externalApplication);
+              }
+              if (dialogContext.mounted) Navigator.pop(dialogContext);
+            },
+            label: t.update.viewRelease,
+            isPrimary: true,
+          ),
+        ],
+      );
+    },
+  );
+}