apps/focus_flow_flutter/lib/app/demo_scheduler_composition.dart

@@ -192,6 +192,19 @@ class DemoSchedulerComposition implements SchedulerAppComposition {
     );
   }
 
+  /// Creates a generic read controller for the settings screen.
+  @override
+  UiReadController<OwnerSettings> createOwnerSettingsController() {
+    return ApplicationReadController<OwnerSettings>(
+      read: () {
+        return managementUseCases.getOwnerSettings(
+          GetOwnerSettingsRequest(context: context('ui-read-owner-settings')),
+        );
+      },
+      isEmpty: (_) => false,
+    );
+  }
+
   /// Creates the command controller used by interactive scheduler controls.
   @override
   SchedulerCommandController createCommandController({
@@ -200,6 +213,7 @@ class DemoSchedulerComposition implements SchedulerAppComposition {
   }) {
     return SchedulerCommandController(
       commands: commandUseCases,
+      management: managementUseCases,
       contextFor: context,
       selectedDate: selectedDate,
       refreshReads: refreshReads,

apps/focus_flow_flutter/lib/app/focus_flow_app.dart

@@ -18,6 +18,7 @@ import '../theme/focus_flow_theme.dart';
 import '../theme/focus_flow_tokens.dart';
 import '../widgets/app_shell.dart';
 import '../widgets/backlog_pane.dart';
+import '../widgets/dialogs/settings_dialog.dart';
 import '../widgets/required_banner.dart';
 import '../widgets/sidebar.dart';
 import '../widgets/task_selection_modal.dart';

apps/focus_flow_flutter/lib/app/home/focus_flow_home_state.dart

@@ -22,6 +22,10 @@ class _FocusFlowHomeState extends State<FocusFlowHome> {
   /// This field is part of the explicit state that downstream scheduling, persistence, or UI code reads when composing behavior.
   late final UiReadController<BacklogQueryResult> backlogController;
 
+  /// Stores the `ownerSettingsController` value for this object.
+  /// This field is part of the explicit state that downstream scheduling, persistence, or UI code reads when composing behavior.
+  late final UiReadController<OwnerSettings> ownerSettingsController;
+
   /// Screen currently shown in the main content area.
   var _activeScreen = SidebarScreen.today;
 
@@ -36,6 +40,8 @@ class _FocusFlowHomeState extends State<FocusFlowHome> {
       selectedDates: selectedDateController,
     );
     backlogController = widget.composition.createBacklogController();
+    ownerSettingsController = widget.composition
+        .createOwnerSettingsController();
     commandController = widget.composition.createCommandController(
       refreshReads: _refreshReads,
       selectedDate: () => selectedDateController.date,
@@ -44,6 +50,8 @@ class _FocusFlowHomeState extends State<FocusFlowHome> {
     controller.load();
     logger.finer(() => 'FocusFlow home triggering initial Backlog load.');
     unawaited(backlogController.load());
+    logger.finer(() => 'FocusFlow home triggering initial settings load.');
+    unawaited(ownerSettingsController.load());
   }
 
   /// Releases resources owned by this object before it leaves the tree.
@@ -54,6 +62,7 @@ class _FocusFlowHomeState extends State<FocusFlowHome> {
     commandController.dispose();
     controller.dispose();
     backlogController.dispose();
+    ownerSettingsController.dispose();
     selectedDateController.dispose();
     unawaited(widget.composition.dispose());
     super.dispose();
@@ -65,6 +74,7 @@ class _FocusFlowHomeState extends State<FocusFlowHome> {
   Future<void> _refreshReads() async {
     await controller.load();
     await backlogController.load();
+    await ownerSettingsController.load();
   }
 
   /// Switches the main content area to the Today screen.
@@ -171,6 +181,33 @@ class _FocusFlowHomeState extends State<FocusFlowHome> {
     );
   }
 
+  /// Opens the settings dialog seeded with the current owner settings and
+  /// applies the confirmed patch, if any.
+  Future<void> _openSettings() async {
+    logger.finer(() => 'Settings action requested.');
+    final state = ownerSettingsController.state;
+    final current = switch (state) {
+      SchedulerReadData(:final value) => value,
+      SchedulerReadEmpty(:final value) => value,
+      _ => null,
+    };
+    if (current == null) {
+      logger.warn(
+        () => 'Settings action ignored: owner settings not yet loaded.',
+      );
+      return;
+    }
+    final update = await showDialog<OwnerSettingsUpdate>(
+      context: context,
+      builder: (_) => SettingsDialog(initial: current),
+    );
+    if (update == null) {
+      logger.finer(() => 'Settings dialog dismissed without changes.');
+      return;
+    }
+    await commandController.updateOwnerSettings(update);
+  }
+
   /// Moves the visible planning date backward by one day.
   void _selectPreviousDate() {
     logger.finer(() => 'Previous date action requested.');
@@ -214,6 +251,9 @@ class _FocusFlowHomeState extends State<FocusFlowHome> {
           activeScreen: _activeScreen,
           onSelectToday: _showToday,
           onSelectBacklog: _showBacklog,
+          onOpenSettings: () {
+            unawaited(_openSettings());
+          },
         ),
         child: switch (_activeScreen) {
           SidebarScreen.today => _buildTodayContent(context),
@@ -253,6 +293,9 @@ class _FocusFlowHomeState extends State<FocusFlowHome> {
             onChooseDate: () {
               unawaited(_chooseDate());
             },
+            onOpenSettings: () {
+              unawaited(_openSettings());
+            },
           ),
           TodayScreenReady(:final data) => _TodayScreenScaffold(
             data: data,
@@ -271,6 +314,9 @@ class _FocusFlowHomeState extends State<FocusFlowHome> {
             onChooseDate: () {
               unawaited(_chooseDate());
             },
+            onOpenSettings: () {
+              unawaited(_openSettings());
+            },
           ),
         };
       },

apps/focus_flow_flutter/lib/app/home/today_screen_scaffold.dart

@@ -23,6 +23,7 @@ class _TodayScreenScaffold extends StatefulWidget {
     required this.onPreviousDate,
     required this.onNextDate,
     required this.onChooseDate,
+    required this.onOpenSettings,
   });
 
   /// Stores the `data` value for this object.
@@ -85,6 +86,10 @@ class _TodayScreenScaffold extends StatefulWidget {
   /// This field is part of the explicit state that downstream scheduling, persistence, or UI code reads when composing behavior.
   final VoidCallback onChooseDate;
 
+  /// Stores the `onOpenSettings` value for this object.
+  /// This field is part of the explicit state that downstream scheduling, persistence, or UI code reads when composing behavior.
+  final VoidCallback onOpenSettings;
+
   /// Creates the mutable state object used by this stateful widget.
   /// Flutter calls this once for each mounted widget instance before lifecycle callbacks and builds begin.
   @override

apps/focus_flow_flutter/lib/app/home/today_screen_scaffold_state.dart

@@ -79,6 +79,7 @@ class _TodayScreenScaffoldState extends State<_TodayScreenScaffold> {
                 onNextDate: widget.onNextDate,
                 onDatePressed: widget.onChooseDate,
                 onDateLabelPressed: _scrollTimelineToCurrentTime,
+                onOpenSettings: widget.onOpenSettings,
               ),
               if (widget.data.requiredBanner == null)
                 const SizedBox(height: 16)

apps/focus_flow_flutter/lib/app/persistent_scheduler_composition.dart

@@ -222,6 +222,22 @@ final class PersistentSchedulerComposition implements SchedulerAppComposition {
     );
   }
 
+  /// Creates a read controller for the settings screen.
+  @override
+  UiReadController<OwnerSettings> createOwnerSettingsController() {
+    scheduler_core.logger.finer(
+      () => 'Creating owner settings read controller.',
+    );
+    return ApplicationReadController<OwnerSettings>(
+      read: () {
+        return managementUseCases.getOwnerSettings(
+          GetOwnerSettingsRequest(context: context('ui-read-owner-settings')),
+        );
+      },
+      isEmpty: (_) => false,
+    );
+  }
+
   /// Creates the command controller used by interactive scheduler controls.
   @override
   SchedulerCommandController createCommandController({
@@ -234,6 +250,7 @@ final class PersistentSchedulerComposition implements SchedulerAppComposition {
     );
     return SchedulerCommandController(
       commands: commandUseCases,
+      management: managementUseCases,
       contextFor: context,
       selectedDate: selectedDate,
       refreshReads: refreshReads,

apps/focus_flow_flutter/lib/app/scheduler_app_composition.dart

@@ -36,6 +36,9 @@ abstract interface class SchedulerAppComposition {
   /// Creates a read controller for the backlog screen.
   UiReadController<BacklogQueryResult> createBacklogController();
 
+  /// Creates a read controller for the settings screen.
+  UiReadController<OwnerSettings> createOwnerSettingsController();
+
   /// Creates the command controller used by interactive scheduler controls.
   SchedulerCommandController createCommandController({
     required ReadRefresh refreshReads,

apps/focus_flow_flutter/lib/controllers/command/scheduler_command_controller_impl.dart

@@ -8,6 +8,7 @@ class SchedulerCommandController extends ChangeNotifier {
   /// Creates a command controller from scheduler use cases and UI callbacks.
   SchedulerCommandController({
     required this.commands,
+    required this.management,
     required this.contextFor,
     required this.selectedDate,
     required this.refreshReads,
@@ -21,6 +22,10 @@ class SchedulerCommandController extends ChangeNotifier {
   /// Scheduler write use cases invoked by this controller.
   final V1ApplicationCommandUseCases commands;
 
+  /// Non-scheduling management use cases (owner settings, projects, locked
+  /// time) invoked by this controller.
+  final V1ApplicationManagementUseCases management;
+
   /// Factory for command-scoped application operation contexts.
   final OperationContextFactory contextFor;
 
@@ -184,7 +189,7 @@ class SchedulerCommandController extends ChangeNotifier {
           TaskType.locked ||
           TaskType.surprise ||
           TaskType.freeSlot => Future.value(
-            ApplicationResult.failure(
+            ApplicationResult<ApplicationCommandResult>.failure(
               ApplicationFailure(
                 code: ApplicationFailureCode.validation,
                 entityId: taskId,
@@ -332,6 +337,31 @@ class SchedulerCommandController extends ChangeNotifier {
     );
   }
 
+  /// Applies a patch to the owner's persisted settings.
+  Future<void> updateOwnerSettings(OwnerSettingsUpdate update) async {
+    final commandAt = now();
+    logger.debug(
+      () =>
+          'UI command requested: update owner settings. '
+          'hasTimeZone=${update.timeZoneId != null} '
+          'hasDayStart=${update.dayStart != null} '
+          'hasDayEnd=${update.dayEnd != null} '
+          'hasCompactMode=${update.compactModeEnabled != null} '
+          'hasStaleness=${update.backlogStalenessSettings != null}',
+    );
+    await _run<OwnerSettingsUpdateResult>(
+      label: 'Saving settings',
+      successMessage: 'Settings saved',
+      refreshAfterSuccess: true,
+      action: (operationId) {
+        return management.updateOwnerSettings(
+          context: contextFor(operationId, now: commandAt),
+          update: update,
+        );
+      },
+    );
+  }
+
   /// Permanently removes a task from persistence.
   Future<void> removeTask({
     required String taskId,
@@ -360,14 +390,11 @@ class SchedulerCommandController extends ChangeNotifier {
 
   /// Runs the `_run` operation and completes after its asynchronous work finishes.
   /// Callers should await the returned future so repository writes, UI refreshes, and failure handling happen in a predictable order.
-  Future<void> _run({
+  Future<void> _run<R>({
     required String label,
     required String successMessage,
     required bool refreshAfterSuccess,
-    required Future<ApplicationResult<ApplicationCommandResult>> Function(
+    required Future<ApplicationResult<R>> Function(String operationId) action,
-      String operationId,
-    )
-    action,
   }) async {
     final operationId = _nextOperationId();
     logger.debug(

apps/focus_flow_flutter/lib/widgets/dialogs/settings_dialog.dart

@@ -0,0 +1,317 @@
+// SPDX-FileCopyrightText: 2026 FocusFlow contributors
+// SPDX-License-Identifier: AGPL-3.0-only
+
+/// Renders the shared Settings dialog for the FocusFlow Flutter UI.
+library;
+
+import 'package:flutter/material.dart';
+import 'package:scheduler_core/scheduler_core.dart';
+
+import '../../theme/focus_flow_tokens.dart';
+
+/// Time zone codes recognized by the app's runtime config loader.
+const _timeZoneOptions = <String>[
+  'UTC',
+  'GMT',
+  'PST',
+  'PDT',
+  'MST',
+  'MDT',
+  'CST',
+  'CDT',
+  'EST',
+  'EDT',
+];
+
+/// Dialog that surfaces persisted [OwnerSettings] fields for editing.
+///
+/// Returns an [OwnerSettingsUpdate] patch containing only the fields the user
+/// changed when confirmed, or `null` when cancelled.
+class SettingsDialog extends StatefulWidget {
+  /// Creates a settings dialog seeded with the currently persisted [initial]
+  /// settings.
+  const SettingsDialog({required this.initial, super.key});
+
+  /// Currently persisted owner settings shown as the dialog's starting
+  /// values.
+  final OwnerSettings initial;
+
+  /// Creates the mutable state object used by this stateful widget.
+  /// Flutter calls this once for each mounted widget instance before lifecycle callbacks and builds begin.
+  @override
+  State<SettingsDialog> createState() => _SettingsDialogState();
+}
+
+/// Private implementation type for `_SettingsDialogState` in this library.
+class _SettingsDialogState extends State<SettingsDialog> {
+  late String _timeZoneId;
+  late WallTime _dayStart;
+  late WallTime _dayEnd;
+  late bool _compactModeEnabled;
+  late final TextEditingController _freshDaysController;
+  late final TextEditingController _agingDaysController;
+
+  /// Validation message for the day window, if any.
+  String? _dayWindowError;
+
+  /// Validation message for the staleness thresholds, if any.
+  String? _stalenessError;
+
+  /// Initializes state owned by this object before the first build.
+  /// Use this lifecycle point for controller setup, initial reads, and listener wiring that must happen once per mounted instance.
+  @override
+  void initState() {
+    super.initState();
+    final initial = widget.initial;
+    _timeZoneId = _timeZoneOptions.contains(initial.timeZoneId.toUpperCase())
+        ? initial.timeZoneId.toUpperCase()
+        : _timeZoneOptions.first;
+    _dayStart = initial.dayStart;
+    _dayEnd = initial.dayEnd;
+    _compactModeEnabled = initial.compactModeEnabled;
+    _freshDaysController = TextEditingController(
+      text: initial.backlogStalenessSettings.greenMaxAge.inDays.toString(),
+    );
+    _agingDaysController = TextEditingController(
+      text: initial.backlogStalenessSettings.blueMaxAge.inDays.toString(),
+    );
+  }
+
+  /// Releases resources owned by this object before it leaves the tree.
+  /// Controllers, listeners, and other disposable collaborators should be cleaned up here to avoid stale callbacks.
+  @override
+  void dispose() {
+    _freshDaysController.dispose();
+    _agingDaysController.dispose();
+    super.dispose();
+  }
+
+  Future<void> _pickDayStart() async {
+    final picked = await showTimePicker(
+      context: context,
+      initialTime: TimeOfDay(hour: _dayStart.hour, minute: _dayStart.minute),
+    );
+    if (picked == null) {
+      return;
+    }
+    setState(() {
+      _dayStart = WallTime(hour: picked.hour, minute: picked.minute);
+      _dayWindowError = null;
+    });
+  }
+
+  Future<void> _pickDayEnd() async {
+    final picked = await showTimePicker(
+      context: context,
+      initialTime: TimeOfDay(hour: _dayEnd.hour, minute: _dayEnd.minute),
+    );
+    if (picked == null) {
+      return;
+    }
+    setState(() {
+      _dayEnd = WallTime(hour: picked.hour, minute: picked.minute);
+      _dayWindowError = null;
+    });
+  }
+
+  void _submit() {
+    if (_dayStart.compareTo(_dayEnd) >= 0) {
+      setState(() => _dayWindowError = 'Day end must be after day start.');
+      return;
+    }
+    final freshDays = int.tryParse(_freshDaysController.text.trim());
+    final agingDays = int.tryParse(_agingDaysController.text.trim());
+    if (freshDays == null ||
+        agingDays == null ||
+        freshDays < 0 ||
+        agingDays < freshDays) {
+      setState(
+        () => _stalenessError =
+            'Aging must be a number of days at least as large as Fresh.',
+      );
+      return;
+    }
+
+    Navigator.of(context).pop(
+      OwnerSettingsUpdate(
+        timeZoneId: _timeZoneId,
+        dayStart: _dayStart,
+        dayEnd: _dayEnd,
+        compactModeEnabled: _compactModeEnabled,
+        backlogStalenessSettings: BacklogStalenessSettings(
+          greenMaxAge: Duration(days: freshDays),
+          blueMaxAge: Duration(days: agingDays),
+        ),
+      ),
+    );
+  }
+
+  /// Builds the widget subtree for this component.
+  /// The method translates the current widget configuration and state into Flutter UI without mutating scheduler domain data.
+  @override
+  Widget build(BuildContext context) {
+    return AlertDialog(
+      backgroundColor: FocusFlowTokens.elevatedPanel,
+      title: const Text(
+        'Settings',
+        style: TextStyle(color: FocusFlowTokens.textPrimary),
+      ),
+      content: SizedBox(
+        width: 420,
+        child: SingleChildScrollView(
+          child: Column(
+            mainAxisSize: MainAxisSize.min,
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              const Text(
+                'Time & day',
+                style: TextStyle(
+                  color: FocusFlowTokens.textPrimary,
+                  fontWeight: FontWeight.w700,
+                ),
+              ),
+              const SizedBox(height: 8),
+              DropdownButtonFormField<String>(
+                key: const ValueKey('settings-timezone'),
+                initialValue: _timeZoneId,
+                decoration: const InputDecoration(labelText: 'Time zone'),
+                items: [
+                  for (final zone in _timeZoneOptions)
+                    DropdownMenuItem(value: zone, child: Text(zone)),
+                ],
+                onChanged: (value) {
+                  if (value == null) {
+                    return;
+                  }
+                  setState(() => _timeZoneId = value);
+                },
+              ),
+              const SizedBox(height: 12),
+              Row(
+                children: [
+                  Expanded(
+                    child: OutlinedButton(
+                      key: const ValueKey('settings-day-start'),
+                      onPressed: _pickDayStart,
+                      child: Text('Day start: ${_dayStart.formatted}'),
+                    ),
+                  ),
+                  const SizedBox(width: 8),
+                  Expanded(
+                    child: OutlinedButton(
+                      key: const ValueKey('settings-day-end'),
+                      onPressed: _pickDayEnd,
+                      child: Text('Day end: ${_dayEnd.formatted}'),
+                    ),
+                  ),
+                ],
+              ),
+              if (_dayWindowError != null) ...[
+                const SizedBox(height: 6),
+                Text(
+                  _dayWindowError!,
+                  style: const TextStyle(color: FocusFlowTokens.accentMagenta),
+                ),
+              ],
+              const SizedBox(height: 20),
+              const Text(
+                'Compact mode',
+                style: TextStyle(
+                  color: FocusFlowTokens.textPrimary,
+                  fontWeight: FontWeight.w700,
+                ),
+              ),
+              SwitchListTile(
+                key: const ValueKey('settings-compact-mode'),
+                contentPadding: EdgeInsets.zero,
+                title: const Text(
+                  'Compact Today view',
+                  style: TextStyle(color: FocusFlowTokens.textPrimary),
+                ),
+                subtitle: const Text(
+                  'Saved now; visual toggle is coming soon.',
+                  style: TextStyle(
+                    color: FocusFlowTokens.textMuted,
+                    fontSize: 12,
+                  ),
+                ),
+                value: _compactModeEnabled,
+                onChanged: (value) {
+                  setState(() => _compactModeEnabled = value);
+                },
+              ),
+              const SizedBox(height: 20),
+              const Text(
+                'Backlog freshness',
+                style: TextStyle(
+                  color: FocusFlowTokens.textPrimary,
+                  fontWeight: FontWeight.w700,
+                ),
+              ),
+              const SizedBox(height: 8),
+              Row(
+                children: [
+                  Expanded(
+                    child: TextField(
+                      key: const ValueKey('settings-fresh-days'),
+                      controller: _freshDaysController,
+                      keyboardType: TextInputType.number,
+                      decoration: const InputDecoration(
+                        labelText: 'Fresh (days)',
+                      ),
+                      onChanged: (_) => setState(() => _stalenessError = null),
+                    ),
+                  ),
+                  const SizedBox(width: 8),
+                  Expanded(
+                    child: TextField(
+                      key: const ValueKey('settings-aging-days'),
+                      controller: _agingDaysController,
+                      keyboardType: TextInputType.number,
+                      decoration: const InputDecoration(
+                        labelText: 'Aging (days)',
+                      ),
+                      onChanged: (_) => setState(() => _stalenessError = null),
+                    ),
+                  ),
+                ],
+              ),
+              const SizedBox(height: 4),
+              const Text(
+                'Anything older than Aging is shown as Stale.',
+                style: TextStyle(
+                  color: FocusFlowTokens.textMuted,
+                  fontSize: 12,
+                ),
+              ),
+              if (_stalenessError != null) ...[
+                const SizedBox(height: 6),
+                Text(
+                  _stalenessError!,
+                  style: const TextStyle(color: FocusFlowTokens.accentMagenta),
+                ),
+              ],
+            ],
+          ),
+        ),
+      ),
+      actions: [
+        TextButton(
+          onPressed: () => Navigator.of(context).pop(),
+          child: const Text('Cancel'),
+        ),
+        FilledButton(
+          key: const ValueKey('settings-save'),
+          onPressed: _submit,
+          child: const Text('Save'),
+        ),
+      ],
+    );
+  }
+}
+
+/// Formats a [WallTime] as `HH:MM`.
+extension on WallTime {
+  String get formatted =>
+      '${hour.toString().padLeft(2, '0')}:${minute.toString().padLeft(2, '0')}';
+}

apps/focus_flow_flutter/lib/widgets/sidebar.dart

@@ -28,6 +28,7 @@ class Sidebar extends StatelessWidget {
     required this.activeScreen,
     required this.onSelectToday,
     required this.onSelectBacklog,
+    required this.onOpenSettings,
     super.key,
   });
 
@@ -40,6 +41,9 @@ class Sidebar extends StatelessWidget {
   /// Invoked when the Backlog nav item is activated.
   final VoidCallback onSelectBacklog;
 
+  /// Invoked when the Settings nav item is activated.
+  final VoidCallback onOpenSettings;
+
   /// Builds the widget subtree for this component.
   /// The method translates the current widget configuration and state into Flutter UI without mutating scheduler domain data.
   @override
@@ -73,7 +77,11 @@ class Sidebar extends StatelessWidget {
             const SizedBox(height: 30),
             const Divider(color: FocusFlowTokens.subtleBorder),
             const SizedBox(height: 18),
-            _NavItem(label: 'Settings', icon: Icons.settings, onTap: () {}),
+            _NavItem(
+              label: 'Settings',
+              icon: Icons.settings,
+              onTap: onOpenSettings,
+            ),
           ],
         ),
       ),

apps/focus_flow_flutter/lib/widgets/top_bar.dart

@@ -22,6 +22,7 @@ class TopBar extends StatelessWidget {
     this.onNextDate,
     this.onDatePressed,
     this.onDateLabelPressed,
+    this.onOpenSettings,
     super.key,
   });
 
@@ -40,6 +41,9 @@ class TopBar extends StatelessWidget {
   /// Callback invoked when the displayed date label is activated.
   final VoidCallback? onDateLabelPressed;
 
+  /// Callback invoked when the Settings button is activated.
+  final VoidCallback? onOpenSettings;
+
   /// Builds the widget subtree for this component.
   /// The method translates the current widget configuration and state into Flutter UI without mutating scheduler domain data.
   @override
@@ -130,7 +134,7 @@ class TopBar extends StatelessWidget {
               const Spacer(),
               _ModeToggle(metrics: metrics),
               SizedBox(width: metrics.settingsGap),
-              _SettingsButton(metrics: metrics),
+              _SettingsButton(metrics: metrics, onPressed: onOpenSettings),
             ],
           ),
         );

apps/focus_flow_flutter/lib/widgets/top_bar/top_bar_settings_button.dart

@@ -8,18 +8,22 @@ part of '../top_bar.dart';
 class _SettingsButton extends StatelessWidget {
   /// Creates a `_SettingsButton` instance with the values required by its invariants.
   /// Callers should pass already-normalized scheduler data because validation and defaulting belong at the model or service boundary, not in arbitrary UI code.
-  const _SettingsButton({required this.metrics});
+  const _SettingsButton({required this.metrics, this.onPressed});
 
   /// Stores the `metrics` value for this object.
   /// This field is part of the explicit state that downstream scheduling, persistence, or UI code reads when composing behavior.
   final _TopBarMetrics metrics;
 
+  /// Callback invoked when the button is activated.
+  final VoidCallback? onPressed;
+
   /// Builds the widget subtree for this component.
   /// The method translates the current widget configuration and state into Flutter UI without mutating scheduler domain data.
   @override
   Widget build(BuildContext context) {
     return OutlinedButton(
-      onPressed: () {},
+      key: const ValueKey('top-bar-settings-button'),
+      onPressed: onPressed,
       style: OutlinedButton.styleFrom(
         foregroundColor: FocusFlowTokens.textPrimary,
         side: BorderSide(

apps/focus_flow_flutter/test/app/settings_test.dart

@@ -0,0 +1,115 @@
+// SPDX-FileCopyrightText: 2026 FocusFlow contributors
+// SPDX-License-Identifier: AGPL-3.0-only
+
+/// Tests app-level settings dialog behavior.
+library;
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:scheduler_core/scheduler_core.dart';
+
+import 'package:focus_flow_flutter/app/demo_scheduler_composition.dart';
+import 'package:focus_flow_flutter/app/focus_flow_app.dart';
+
+/// Runs app-level settings dialog tests.
+void main() {
+  testWidgets('sidebar Settings opens a dialog seeded with persisted values', (
+    tester,
+  ) async {
+    await _pumpPlanApp(tester);
+
+    await tester.tap(find.byKey(const ValueKey('nav-settings')));
+    await tester.pumpAndSettle();
+
+    expect(find.byType(AlertDialog), findsOneWidget);
+    expect(find.text('UTC'), findsOneWidget);
+
+    final compactSwitch = tester.widget<SwitchListTile>(
+      find.byKey(const ValueKey('settings-compact-mode')),
+    );
+    expect(compactSwitch.value, isTrue);
+
+    await tester.tap(find.text('Cancel'));
+    await tester.pumpAndSettle();
+
+    expect(find.byType(AlertDialog), findsNothing);
+  });
+
+  testWidgets('top bar Settings button opens the same dialog', (tester) async {
+    await _pumpPlanApp(tester);
+
+    await tester.tap(find.byKey(const ValueKey('top-bar-settings-button')));
+    await tester.pumpAndSettle();
+
+    expect(find.byKey(const ValueKey('settings-timezone')), findsOneWidget);
+
+    await tester.tap(find.text('Cancel'));
+    await tester.pumpAndSettle();
+  });
+
+  testWidgets('saving settings persists the change and reopens with it', (
+    tester,
+  ) async {
+    await _pumpPlanApp(tester);
+
+    await tester.tap(find.byKey(const ValueKey('nav-settings')));
+    await tester.pumpAndSettle();
+
+    await tester.tap(find.byKey(const ValueKey('settings-timezone')));
+    await tester.pumpAndSettle();
+    await tester.tap(find.text('EST').last);
+    await tester.pumpAndSettle();
+
+    await tester.tap(find.byKey(const ValueKey('settings-save')));
+    await tester.pumpAndSettle();
+
+    expect(find.byType(AlertDialog), findsNothing);
+
+    await tester.tap(find.byKey(const ValueKey('nav-settings')));
+    await tester.pumpAndSettle();
+
+    expect(find.text('EST'), findsOneWidget);
+
+    await tester.tap(find.text('Cancel'));
+    await tester.pumpAndSettle();
+  });
+
+  testWidgets('invalid staleness thresholds show a calm inline error', (
+    tester,
+  ) async {
+    await _pumpPlanApp(tester);
+
+    await tester.tap(find.byKey(const ValueKey('nav-settings')));
+    await tester.pumpAndSettle();
+
+    await tester.enterText(
+      find.byKey(const ValueKey('settings-aging-days')),
+      '1',
+    );
+    await tester.pumpAndSettle();
+    await tester.tap(find.byKey(const ValueKey('settings-save')));
+    await tester.pumpAndSettle();
+
+    expect(find.byType(AlertDialog), findsOneWidget);
+    expect(
+      find.text('Aging must be a number of days at least as large as Fresh.'),
+      findsOneWidget,
+    );
+
+    await tester.tap(find.text('Cancel'));
+    await tester.pumpAndSettle();
+  });
+}
+
+/// Pumps the FocusFlow app at the desktop test size.
+Future<void> _pumpPlanApp(WidgetTester tester) async {
+  await tester.binding.setSurfaceSize(const Size(1586, 992));
+  addTearDown(() => tester.binding.setSurfaceSize(null));
+  await tester.pumpWidget(FocusFlowApp(composition: _composition()));
+  await tester.pumpAndSettle();
+}
+
+/// Builds the seeded demo composition used by settings dialog tests.
+DemoSchedulerComposition _composition() {
+  return DemoSchedulerComposition.seeded(selectedDate: CivilDate(2025, 5, 20));
+}

apps/focus_flow_flutter/test/persistent_composition_test.dart

@@ -552,6 +552,7 @@ SchedulerCommandController _commandController(
 }) {
   return SchedulerCommandController(
     commands: composition.commandUseCases,
+    management: composition.managementUseCases,
     contextFor: composition.context,
     selectedDate: () => selectedDate,
     refreshReads: () async {},

packages/scheduler_core/lib/src/application/application_management.dart

@@ -29,6 +29,7 @@ part 'application_management/drafts/project_profile_draft.dart';
 part 'application_management/updates/project_profile_update.dart';
 part 'application_management/drafts/locked_block_draft.dart';
 part 'application_management/updates/locked_block_update.dart';
+part 'application_management/requests/get_owner_settings_request.dart';
 part 'application_management/results/owner_settings_update_result.dart';
 part 'application_management/updates/owner_settings_update.dart';
 part 'application_management/results/notice_acknowledgement_result.dart';

packages/scheduler_core/lib/src/application/application_management/requests/get_owner_settings_request.dart

@@ -0,0 +1,14 @@
+// SPDX-FileCopyrightText: 2026 FocusFlow contributors
+// SPDX-License-Identifier: AGPL-3.0-only
+
+part of '../../application_management.dart';
+
+/// Owner settings query request.
+class GetOwnerSettingsRequest {
+  /// Creates a `GetOwnerSettingsRequest` instance with the values required by its invariants.
+  /// Callers should pass already-normalized scheduler data because validation and defaulting belong at the model or service boundary, not in arbitrary UI code.
+  const GetOwnerSettingsRequest({required this.context});
+
+  /// Read context containing owner scope and read instant.
+  final ApplicationOperationContext context;
+}

packages/scheduler_core/lib/src/application/application_management/use_cases/v1_application_management_use_cases.dart

@@ -116,6 +116,24 @@ class V1ApplicationManagementUseCases {
     );
   }
 
+  /// Load the effective owner settings, falling back to defaults when none
+  /// have been persisted yet.
+  Future<ApplicationResult<OwnerSettings>> getOwnerSettings(
+    GetOwnerSettingsRequest request,
+  ) {
+    return applicationStore.read(
+      action: (repositories) async {
+        final ownerId = request.context.ownerTimeZone.ownerId;
+        logger.debug(() => 'Loading owner settings query. ownerId=$ownerId');
+        final settings = await _ownerSettingsOrDefault(
+          repositories,
+          request.context.ownerTimeZone,
+        );
+        return ApplicationResult.success(settings);
+      },
+    );
+  }
+
   /// Runs the `createProject` operation and completes after its asynchronous work finishes.
   /// Callers should await the returned future so repository writes, UI refreshes, and failure handling happen in a predictable order.
   Future<ApplicationResult<ProjectProfile>> createProject({