feat(backlog): schedule suggested slots

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

@@ -134,6 +134,38 @@ class SchedulerCommandController extends ChangeNotifier {
     );
   }
 
+  /// Schedules a backlog task into a specific suggested slot.
+  Future<void> scheduleBacklogItemAtSuggestedSlot({
+    required String taskId,
+    required DateTime scheduledStartUtc,
+    required DateTime scheduledEndUtc,
+    required DateTime expectedUpdatedAt,
+  }) async {
+    logger.debug(
+      () =>
+          'UI command requested: schedule backlog item at suggested slot. '
+          'taskId=$taskId scheduledStart=${scheduledStartUtc.toIso8601String()} '
+          'scheduledEnd=${scheduledEndUtc.toIso8601String()} '
+          'expectedUpdatedAt=${expectedUpdatedAt.toIso8601String()}',
+    );
+    await _run(
+      label: 'Scheduling task',
+      successMessage: 'Task scheduled',
+      refreshAfterSuccess: true,
+      action: (operationId) {
+        final commandAt = now();
+        return commands.scheduleBacklogItemAtSuggestedSlot(
+          context: contextFor(operationId, now: commandAt),
+          localDate: selectedDate(),
+          taskId: taskId,
+          scheduledStart: scheduledStartUtc,
+          scheduledEnd: scheduledEndUtc,
+          expectedUpdatedAt: expectedUpdatedAt,
+        );
+      },
+    );
+  }
+
   /// Breaks a Backlog task into direct child tasks.
   Future<void> breakUpBacklogTask({
     required String parentTaskId,

apps/focus_flow_flutter/lib/widgets/backlog/backlog_board_screen.dart

@@ -57,6 +57,21 @@ class BacklogBoardScreen extends StatelessWidget {
           );
         }
 
+        void scheduleSuggestedSlot(SuggestedSlotReadModel slot) {
+          final detail = controller.selectedTaskDetail;
+          if (detail == null) {
+            return;
+          }
+          unawaited(
+            _scheduleSelectedBacklogTaskAtSuggestedSlot(
+              detail: detail,
+              slot: slot,
+              boardController: controller,
+              commandController: commandController,
+            ),
+          );
+        }
+
         void breakUpSelectedTask() {
           final detail = controller.selectedTaskDetail;
           if (detail == null) {
@@ -137,6 +152,7 @@ class BacklogBoardScreen extends StatelessWidget {
               onCloseDrawer: controller.clearSelection,
               onAddTask: _addTaskHandler(context, commandController),
               onSchedule: scheduleSelectedTask,
+              onSuggestedSlotPressed: scheduleSuggestedSlot,
               onBreakUp: breakUpSelectedTask,
               onPushToSomeday: pushSelectedTaskToSomeday,
               onRemove: removeSelectedTask,
@@ -161,6 +177,7 @@ class BacklogBoardScreen extends StatelessWidget {
               onCloseDrawer: controller.clearSelection,
               onAddTask: _addTaskHandler(context, commandController),
               onSchedule: scheduleSelectedTask,
+              onSuggestedSlotPressed: scheduleSuggestedSlot,
               onBreakUp: breakUpSelectedTask,
               onPushToSomeday: pushSelectedTaskToSomeday,
               onRemove: removeSelectedTask,
@@ -764,6 +781,28 @@ Future<void> _scheduleSelectedBacklogTask({
   }
 }
 
+/// Schedules the selected Backlog [detail] at the exact suggested [slot].
+Future<void> _scheduleSelectedBacklogTaskAtSuggestedSlot({
+  required BacklogTaskDetailReadModel detail,
+  required SuggestedSlotReadModel slot,
+  required BacklogBoardController boardController,
+  required SchedulerCommandController? commandController,
+}) async {
+  final commands = commandController;
+  if (commands == null) {
+    return;
+  }
+  await commands.scheduleBacklogItemAtSuggestedSlot(
+    taskId: detail.item.taskId,
+    scheduledStartUtc: slot.startUtc,
+    scheduledEndUtc: slot.endUtc,
+    expectedUpdatedAt: detail.item.updatedAt,
+  );
+  if (commands.state is SchedulerCommandSuccess) {
+    boardController.clearSelection();
+  }
+}
+
 /// Main Backlog frame containing header, controls, body, and overlay slot.
 class _BacklogFrame extends StatelessWidget {
   /// Creates the Backlog frame.
@@ -1003,6 +1042,7 @@ class _BacklogReadyBody extends StatelessWidget {
     required this.onCloseDrawer,
     required this.onAddTask,
     required this.onSchedule,
+    required this.onSuggestedSlotPressed,
     required this.onBreakUp,
     required this.onPushToSomeday,
     required this.onRemove,
@@ -1039,6 +1079,9 @@ class _BacklogReadyBody extends StatelessWidget {
   /// Callback invoked when the drawer Schedule action is pressed.
   final VoidCallback onSchedule;
 
+  /// Callback invoked when a drawer suggested slot is pressed.
+  final ValueChanged<SuggestedSlotReadModel> onSuggestedSlotPressed;
+
   /// Callback invoked when the drawer Break Up action is pressed.
   final VoidCallback onBreakUp;
 
@@ -1099,6 +1142,7 @@ class _BacklogReadyBody extends StatelessWidget {
                   actionMessage: detailActionMessage,
                   onClose: onCloseDrawer,
                   onSchedule: onSchedule,
+                  onSuggestedSlotPressed: onSuggestedSlotPressed,
                   onBreakUp: onBreakUp,
                   onPushToSomeday: onPushToSomeday,
                   onRemove: onRemove,

apps/focus_flow_flutter/lib/widgets/backlog/backlog_task_drawer.dart

@@ -26,6 +26,7 @@ class BacklogTaskDrawer extends StatelessWidget {
     required this.onBreakUp,
     required this.onPushToSomeday,
     required this.onRemove,
+    required this.onSuggestedSlotPressed,
     required this.onProjectPressed,
     required this.onAddTagPressed,
     required this.onViewDayPressed,
@@ -62,6 +63,9 @@ class BacklogTaskDrawer extends StatelessWidget {
   /// Callback for the Remove action.
   final VoidCallback onRemove;
 
+  /// Callback for scheduling one suggested slot.
+  final ValueChanged<SuggestedSlotReadModel> onSuggestedSlotPressed;
+
   /// Callback for the project selector placeholder.
   final VoidCallback onProjectPressed;
 
@@ -105,6 +109,7 @@ class BacklogTaskDrawer extends StatelessWidget {
                 onBreakUp: onBreakUp,
                 onPushToSomeday: onPushToSomeday,
                 onRemove: onRemove,
+                onSuggestedSlotPressed: onSuggestedSlotPressed,
                 onProjectPressed: onProjectPressed,
                 onAddTagPressed: onAddTagPressed,
                 onViewDayPressed: onViewDayPressed,
@@ -194,6 +199,7 @@ class _DrawerDetailContent extends StatelessWidget {
     required this.onBreakUp,
     required this.onPushToSomeday,
     required this.onRemove,
+    required this.onSuggestedSlotPressed,
     required this.onProjectPressed,
     required this.onAddTagPressed,
     required this.onViewDayPressed,
@@ -218,6 +224,9 @@ class _DrawerDetailContent extends StatelessWidget {
   /// Callback for Remove.
   final VoidCallback onRemove;
 
+  /// Callback for scheduling one suggested slot.
+  final ValueChanged<SuggestedSlotReadModel> onSuggestedSlotPressed;
+
   /// Callback for the project selector placeholder.
   final VoidCallback onProjectPressed;
 
@@ -258,6 +267,7 @@ class _DrawerDetailContent extends StatelessWidget {
                 _SuggestedSlotsSection(
                   slots: detail.suggestedSlots,
                   unavailableReason: detail.suggestedSlotUnavailableReason,
+                  onSuggestedSlotPressed: onSuggestedSlotPressed,
                   onViewDayPressed: onViewDayPressed,
                 ),
               ],
@@ -814,6 +824,7 @@ class _SuggestedSlotsSection extends StatelessWidget {
   const _SuggestedSlotsSection({
     required this.slots,
     required this.unavailableReason,
+    required this.onSuggestedSlotPressed,
     required this.onViewDayPressed,
   });
 
@@ -823,6 +834,9 @@ class _SuggestedSlotsSection extends StatelessWidget {
   /// Optional reason why suggestions are unavailable.
   final String? unavailableReason;
 
+  /// Callback for scheduling a suggested slot.
+  final ValueChanged<SuggestedSlotReadModel> onSuggestedSlotPressed;
+
   /// View-day callback.
   final VoidCallback onViewDayPressed;
 
@@ -855,7 +869,12 @@ class _SuggestedSlotsSection extends StatelessWidget {
             )
           else
             for (final slot in slots) ...[
-              _SuggestedSlotRow(slot: slot),
+              _SuggestedSlotRow(
+                slot: slot,
+                onPressed: () {
+                  onSuggestedSlotPressed(slot);
+                },
+              ),
               if (slot != slots.last) const SizedBox(height: 8),
             ],
         ],
@@ -867,74 +886,85 @@ class _SuggestedSlotsSection extends StatelessWidget {
 /// One suggested schedule slot row.
 class _SuggestedSlotRow extends StatelessWidget {
   /// Creates a suggested slot row.
-  const _SuggestedSlotRow({required this.slot});
+  const _SuggestedSlotRow({required this.slot, required this.onPressed});
 
   /// Suggested slot data.
   final SuggestedSlotReadModel slot;
 
+  /// Callback that schedules this exact slot.
+  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) {
     final severity = _fitSeverityColor(slot.fitSeverityToken);
-    return DecoratedBox(
+    return Material(
-      decoration: BoxDecoration(
+      color: Colors.transparent,
-        color: FocusFlowTokens.panelBackground,
+      child: InkWell(
+        key: ValueKey('backlog-drawer-suggested-slot-${slot.id}'),
         borderRadius: BorderRadius.circular(8),
-        border: Border.all(
+        onTap: onPressed,
-          color: slot.isPrimary
+        child: DecoratedBox(
-              ? FocusFlowTokens.accentMagenta
+          decoration: BoxDecoration(
-              : severity.withValues(alpha: 0.55),
+            color: FocusFlowTokens.panelBackground,
-        ),
+            borderRadius: BorderRadius.circular(8),
-      ),
+            border: Border.all(
-      child: Padding(
+              color: slot.isPrimary
-        padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 9),
+                  ? FocusFlowTokens.accentMagenta
-        child: Row(
+                  : severity.withValues(alpha: 0.55),
-          children: [
-            const Icon(
-              Icons.calendar_today_outlined,
-              color: FocusFlowTokens.textMuted,
-              size: 17,
             ),
-            const SizedBox(width: 10),
+          ),
-            Expanded(
+          child: Padding(
-              child: Column(
+            padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 9),
-                crossAxisAlignment: CrossAxisAlignment.start,
+            child: Row(
-                children: [
+              children: [
-                  Text(
+                const Icon(
-                    slot.localDateLabel,
+                  Icons.calendar_today_outlined,
-                    maxLines: 1,
+                  color: FocusFlowTokens.textMuted,
-                    overflow: TextOverflow.ellipsis,
+                  size: 17,
-                    style: TextStyle(
+                ),
-                      color: slot.isPrimary
+                const SizedBox(width: 10),
-                          ? BacklogBoardVisualTokens.doNextAccent
+                Expanded(
-                          : FocusFlowTokens.textMuted,
+                  child: Column(
-                      fontSize: 12,
+                    crossAxisAlignment: CrossAxisAlignment.start,
-                      fontWeight: FontWeight.w800,
+                    children: [
-                    ),
+                      Text(
+                        slot.localDateLabel,
+                        maxLines: 1,
+                        overflow: TextOverflow.ellipsis,
+                        style: TextStyle(
+                          color: slot.isPrimary
+                              ? BacklogBoardVisualTokens.doNextAccent
+                              : FocusFlowTokens.textMuted,
+                          fontSize: 12,
+                          fontWeight: FontWeight.w800,
+                        ),
+                      ),
+                      const SizedBox(height: 4),
+                      Text(
+                        '${slot.startText} - ${slot.endText} | ${slot.durationMinutes} min',
+                        maxLines: 1,
+                        overflow: TextOverflow.ellipsis,
+                        style: const TextStyle(
+                          color: FocusFlowTokens.textPrimary,
+                          fontSize: 12,
+                        ),
+                      ),
+                    ],
                   ),
-                  const SizedBox(height: 4),
+                ),
-                  Text(
+                const SizedBox(width: 8),
-                    '${slot.startText} - ${slot.endText} | ${slot.durationMinutes} min',
+                _FitBadge(label: slot.fitLabel, color: severity),
-                    maxLines: 1,
+                const SizedBox(width: 4),
-                    overflow: TextOverflow.ellipsis,
+                const Icon(
-                    style: const TextStyle(
+                  Icons.chevron_right,
-                      color: FocusFlowTokens.textPrimary,
+                  color: FocusFlowTokens.textMuted,
-                      fontSize: 12,
+                  size: 20,
-                    ),
+                ),
-                  ),
+              ],
-                ],
-              ),
             ),
-            const SizedBox(width: 8),
+          ),
-            _FitBadge(label: slot.fitLabel, color: severity),
-            const SizedBox(width: 4),
-            const Icon(
-              Icons.chevron_right,
-              color: FocusFlowTokens.textMuted,
-              size: 20,
-            ),
-          ],
         ),
       ),
     );

apps/focus_flow_flutter/test/widgets/backlog_board_screen_test.dart

@@ -266,6 +266,62 @@ void main() {
     expect(find.byKey(const ValueKey('backlog-card-plan-week')), findsNothing);
   });
 
+  testWidgets('suggested slot action schedules the indicated time', (
+    tester,
+  ) async {
+    final existingFlexible = Task(
+      id: 'existing-flexible',
+      title: 'Existing flexible',
+      projectId: 'home',
+      type: TaskType.flexible,
+      status: TaskStatus.planned,
+      priority: PriorityLevel.medium,
+      reward: RewardLevel.medium,
+      difficulty: DifficultyLevel.easy,
+      durationMinutes: 30,
+      scheduledStart: _now,
+      scheduledEnd: _now.add(const Duration(minutes: 30)),
+      createdAt: _now,
+      updatedAt: _now,
+    );
+    final harness = _BacklogCommandHarness.withTasks([
+      _domainBacklogTask(
+        id: 'plan-slot',
+        title: 'Plan slot',
+        durationMinutes: 30,
+      ),
+      existingFlexible,
+    ]);
+    addTearDown(harness.dispose);
+
+    await harness.boardController.load();
+    await _pumpBacklogScreen(
+      tester,
+      harness.boardController,
+      commandController: harness.commandController,
+    );
+
+    await tester.tap(find.byKey(const ValueKey('backlog-card-plan-slot')));
+    await tester.pumpAndSettle();
+    final suggestedSlot = find.byKey(
+      const ValueKey('backlog-drawer-suggested-slot-plan-slot:primary'),
+    );
+    await tester.ensureVisible(suggestedSlot);
+    await tester.tap(suggestedSlot);
+    await _settleAsyncUi(tester);
+
+    expect(harness.commandController.state, isA<SchedulerCommandSuccess>());
+    expect(find.text('Task scheduled'), findsOneWidget);
+    expect(find.byKey(const ValueKey('backlog-task-drawer')), findsNothing);
+    final scheduled = _taskById(harness.store.currentTasks, 'plan-slot');
+    final pushed = _taskById(harness.store.currentTasks, 'existing-flexible');
+    expect(scheduled.status, TaskStatus.planned);
+    expect(scheduled.scheduledStart, _now);
+    expect(scheduled.scheduledEnd, _now.add(const Duration(minutes: 30)));
+    expect(pushed.scheduledStart, _now.add(const Duration(minutes: 30)));
+    expect(pushed.scheduledEnd, _now.add(const Duration(minutes: 60)));
+  });
+
   testWidgets(
     'schedule action explains missing duration without command write',
     (tester) async {

apps/focus_flow_flutter/test/widgets/backlog_task_drawer_test.dart

@@ -23,6 +23,7 @@ void main() {
     var removeCount = 0;
     var addTagCount = 0;
     var viewDayCount = 0;
+    var suggestedSlotId = '';
 
     await _pumpDrawer(
       tester,
@@ -47,6 +48,9 @@ void main() {
         onRemove: () {
           removeCount += 1;
         },
+        onSuggestedSlotPressed: (slot) {
+          suggestedSlotId = slot.id;
+        },
         onProjectPressed: () {},
         onAddTagPressed: () {
           addTagCount += 1;
@@ -85,6 +89,12 @@ void main() {
     await tester.tap(
       find.byKey(const ValueKey('backlog-drawer-view-day-button')),
     );
+    final suggestedSlot = find.byKey(
+      const ValueKey('backlog-drawer-suggested-slot-slot-1'),
+    );
+    await tester.ensureVisible(suggestedSlot);
+    await tester.pump();
+    await tester.tap(suggestedSlot);
     await tester.tap(
       find.byKey(const ValueKey('backlog-drawer-add-tag-button')),
     );
@@ -103,6 +113,7 @@ void main() {
     await tester.tap(find.byKey(const ValueKey('backlog-drawer-close-button')));
 
     expect(viewDayCount, 1);
+    expect(suggestedSlotId, 'slot-1');
     expect(addTagCount, 1);
     expect(scheduleCount, 1);
     expect(breakUpCount, 1);
@@ -127,6 +138,7 @@ void main() {
         onBreakUp: () {},
         onPushToSomeday: () {},
         onRemove: () {},
+        onSuggestedSlotPressed: (_) {},
         onProjectPressed: () {},
         onAddTagPressed: () {},
         onViewDayPressed: () {},
@@ -149,6 +161,7 @@ void main() {
         onBreakUp: () {},
         onPushToSomeday: () {},
         onRemove: () {},
+        onSuggestedSlotPressed: (_) {},
         onProjectPressed: () {},
         onAddTagPressed: () {},
         onViewDayPressed: () {},
@@ -214,9 +227,11 @@ BacklogTaskDetailReadModel _detail() {
         isArchived: false,
       ),
     ],
-    suggestedSlots: const [
+    suggestedSlots: [
       SuggestedSlotReadModel(
         id: 'slot-1',
+        startUtc: DateTime.utc(2026, 7, 7, 14, 30),
+        endUtc: DateTime.utc(2026, 7, 7, 15, 30),
         localDateLabel: 'Today',
         startText: '2:30 PM',
         endText: '3:30 PM',
@@ -227,6 +242,8 @@ BacklogTaskDetailReadModel _detail() {
       ),
       SuggestedSlotReadModel(
         id: 'slot-2',
+        startUtc: DateTime.utc(2026, 7, 7, 18),
+        endUtc: DateTime.utc(2026, 7, 7, 19),
         localDateLabel: 'Today',
         startText: '6:00 PM',
         endText: '7:00 PM',
@@ -237,6 +254,8 @@ BacklogTaskDetailReadModel _detail() {
       ),
       SuggestedSlotReadModel(
         id: 'slot-3',
+        startUtc: DateTime.utc(2026, 7, 8, 10),
+        endUtc: DateTime.utc(2026, 7, 8, 11),
         localDateLabel: 'Tomorrow',
         startText: '10:00 AM',
         endText: '11:00 AM',

packages/scheduler_core/lib/src/application/application_commands/codes/application_command_code.dart

@@ -17,6 +17,10 @@ enum ApplicationCommandCode {
   /// Code should use this named value when it needs this exact scheduler state, presentation token, or persistence meaning.
   scheduleBacklogItemToNextAvailableSlot,
 
+  /// Selects the `scheduleBacklogItemAtSuggestedSlot` option from this enum.
+  /// Code should use this named value when it needs this exact scheduler state, presentation token, or persistence meaning.
+  scheduleBacklogItemAtSuggestedSlot,
+
   /// Selects the `pushFlexibleToNextAvailableSlot` option from this enum.
   /// Code should use this named value when it needs this exact scheduler state, presentation token, or persistence meaning.
   pushFlexibleToNextAvailableSlot,

packages/scheduler_core/lib/src/application/application_commands/use_cases/v1_application_command_use_cases.dart

@@ -285,6 +285,88 @@ class V1ApplicationCommandUseCases {
     );
   }
 
+  /// Schedule an existing backlog item into a selected suggested slot.
+  Future<ApplicationResult<ApplicationCommandResult>>
+      scheduleBacklogItemAtSuggestedSlot({
+    required ApplicationOperationContext context,
+    required CivilDate localDate,
+    required String taskId,
+    required DateTime scheduledStart,
+    required DateTime scheduledEnd,
+    DateTime? expectedUpdatedAt,
+  }) {
+    const commandCode =
+        ApplicationCommandCode.scheduleBacklogItemAtSuggestedSlot;
+    return applicationStore.run<ApplicationCommandResult>(
+      context: context,
+      operationName: commandCode.name,
+      action: (repositories) async {
+        logger.debug(() =>
+            'Application command executing. command=${commandCode.name} '
+            'operationId=${context.operationId} localDate=${localDate.toIsoString()} '
+            'taskId=$taskId scheduledStart=${scheduledStart.toIso8601String()} '
+            'scheduledEnd=${scheduledEnd.toIso8601String()}');
+        var state = await _loadPlanningState(repositories, context, localDate);
+        var task = _taskById(state.tasks, taskId);
+        if (task == null) {
+          logger.finer(() =>
+              'Planning-state task lookup missed; reading by id. '
+              'command=${commandCode.name} taskId=$taskId operationId=${context.operationId}');
+          task = await repositories.tasks.findById(taskId);
+          if (task != null) {
+            state = state.withTask(task);
+          }
+        }
+        if (task == null) {
+          return _failure(ApplicationFailureCode.notFound, entityId: taskId);
+        }
+        final staleFailure = _staleFailure(task, expectedUpdatedAt);
+        if (staleFailure != null) {
+          return ApplicationResult.failure(staleFailure);
+        }
+
+        final schedulingResult =
+            const SchedulingEngine().insertBacklogTaskAtRequestedSlot(
+          input: state.input,
+          taskId: taskId,
+          requestedStart: scheduledStart.toUtc(),
+          requestedEnd: scheduledEnd.toUtc(),
+          updatedAt: context.now,
+        );
+        final schedulingFailure = _failureForSchedulingResult(
+          schedulingResult,
+          entityId: taskId,
+        );
+        if (schedulingFailure != null) {
+          return ApplicationResult.failure(schedulingFailure);
+        }
+
+        final activities = _activitiesForSchedulingChanges(
+          result: schedulingResult,
+          beforeTasks: state.tasks,
+          operationId: context.operationId,
+          occurredAt: context.now,
+          selectedTaskId: taskId,
+          selectedActivityCode: TaskActivityCode.restoredFromBacklog,
+          movedActivityCode: TaskActivityCode.automaticallyPushed,
+        );
+        return _persist(
+          repositories: repositories,
+          commandCode: commandCode,
+          context: context,
+          beforeTasks: state.tasks,
+          afterTasks: schedulingResult.tasks,
+          activities: activities,
+          schedulingResult: schedulingResult,
+          readHint: ApplicationCommandReadHint(
+            localDate: localDate,
+            affectedTaskIds: _taskIdsFromChanges(schedulingResult.changes),
+          ),
+        );
+      },
+    );
+  }
+
   /// Push a planned flexible task later in the same local day.
   Future<ApplicationResult<ApplicationCommandResult>>
       pushFlexibleToNextAvailableSlot({

packages/scheduler_core/lib/src/application/application_management/read_models/backlog_board/suggested_slot_read_model.dart

@@ -8,6 +8,8 @@ class SuggestedSlotReadModel {
   /// Creates a suggested slot preview.
   const SuggestedSlotReadModel({
     required this.id,
+    required this.startUtc,
+    required this.endUtc,
     required this.localDateLabel,
     required this.startText,
     required this.endText,
@@ -20,6 +22,12 @@ class SuggestedSlotReadModel {
   /// Stable suggestion id.
   final String id;
 
+  /// UTC instant where the suggested slot starts.
+  final DateTime startUtc;
+
+  /// UTC instant where the suggested slot ends.
+  final DateTime endUtc;
+
   /// Display label for the owner-local date.
   final String localDateLabel;
 

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

@@ -1535,6 +1535,8 @@ SuggestedSlotReadModel _suggestedSlotReadModel({
 }) {
   return SuggestedSlotReadModel(
     id: id,
+    startUtc: interval.start.toUtc(),
+    endUtc: interval.end.toUtc(),
     localDateLabel: localDateLabel,
     startText: _clockText(interval.start),
     endText: _clockText(interval.end),

packages/scheduler_core/lib/src/persistence/document_mapping/enums/persistence_enum_mapping.dart

@@ -249,6 +249,7 @@ abstract final class PersistenceEnumMapping {
         SchedulingIssueCode.missingDuration => 'missing_duration',
         SchedulingIssueCode.missingScheduledSlot => 'missing_scheduled_slot',
         SchedulingIssueCode.nonPositiveDuration => 'non_positive_duration',
+        SchedulingIssueCode.durationMismatch => 'duration_mismatch',
         SchedulingIssueCode.noAvailableSlot => 'no_available_slot',
         SchedulingIssueCode.unfinishedTasksCouldNotFit =>
           'unfinished_tasks_could_not_fit',

packages/scheduler_core/lib/src/persistence/document_mapping/projects/project_statistics_document_extension.dart

@@ -147,6 +147,7 @@ const _schedulingIssueCodeByCode = <String, SchedulingIssueCode>{
   'missing_duration': SchedulingIssueCode.missingDuration,
   'missing_scheduled_slot': SchedulingIssueCode.missingScheduledSlot,
   'non_positive_duration': SchedulingIssueCode.nonPositiveDuration,
+  'duration_mismatch': SchedulingIssueCode.durationMismatch,
   'no_available_slot': SchedulingIssueCode.noAvailableSlot,
   'unfinished_tasks_could_not_fit':
       SchedulingIssueCode.unfinishedTasksCouldNotFit,

packages/scheduler_core/lib/src/scheduling/scheduling_engine/codes/notices/scheduling_issue_code.dart

@@ -25,6 +25,10 @@ enum SchedulingIssueCode {
   /// Code should use this named value when it needs this exact scheduler state, presentation token, or persistence meaning.
   nonPositiveDuration,
 
+  /// Selects the `durationMismatch` option from this enum.
+  /// Code should use this named value when it needs this exact scheduler state, presentation token, or persistence meaning.
+  durationMismatch,
+
   /// Selects the `noAvailableSlot` option from this enum.
   /// Code should use this named value when it needs this exact scheduler state, presentation token, or persistence meaning.
   noAvailableSlot,

packages/scheduler_core/lib/src/scheduling/scheduling_engine/codes/operations/scheduling_operation_code.dart

@@ -11,6 +11,9 @@ enum SchedulingOperationCode {
   /// Insert a backlog task into the next available slot.
   insertBacklogTaskIntoNextAvailableSlot,
 
+  /// Insert a backlog task into an explicitly requested open slot.
+  insertBacklogTaskAtRequestedSlot,
+
   /// Push a flexible task later in the current window.
   pushFlexibleTaskToNextAvailableSlot,
 

packages/scheduler_core/lib/src/scheduling/scheduling_engine/engine/scheduling_engine.dart

@@ -11,6 +11,7 @@ part of '../../scheduling_engine.dart';
 ///
 /// Current V1 responsibilities:
 /// - insert backlog tasks into the earliest available flexible slot;
+/// - insert backlog tasks into an explicitly selected open slot;
 /// - push flexible tasks later today;
 /// - move flexible tasks to tomorrow's queue;
 /// - roll unfinished flexible tasks into a new planning window;
@@ -137,6 +138,163 @@ class SchedulingEngine {
     );
   }
 
+  /// Insert a backlog task into a specific open interval.
+  ///
+  /// The requested interval must be fully inside [input.window], match the
+  /// backlog task's duration, and avoid fixed blocked time. Existing planned
+  /// flexible tasks that overlap or follow the requested slot may move later,
+  /// preserving their relative order.
+  SchedulingResult insertBacklogTaskAtRequestedSlot({
+    required SchedulingInput input,
+    required String taskId,
+    required DateTime requestedStart,
+    required DateTime requestedEnd,
+    DateTime? updatedAt,
+  }) {
+    logger.debug(() => 'Scheduling backlog task into requested slot. '
+        'taskId=$taskId taskCount=${input.tasks.length} '
+        'requestedStart=${requestedStart.toIso8601String()} '
+        'requestedEnd=${requestedEnd.toIso8601String()}');
+    final task = _taskById(input.tasks, taskId);
+    if (task == null) {
+      logger.warn(() =>
+          'Requested-slot backlog scheduling failed: task not found. taskId=$taskId');
+      return _unchangedResult(
+        input,
+        SchedulingNotice(
+          'Task was not found.',
+          type: SchedulingNoticeType.noFit,
+          taskId: taskId,
+          issueCode: SchedulingIssueCode.taskNotFound,
+        ),
+        operationCode: SchedulingOperationCode.insertBacklogTaskAtRequestedSlot,
+        outcomeCode: SchedulingOutcomeCode.notFound,
+      );
+    }
+
+    if (!task.isFlexible || !task.isBacklog) {
+      logger.warn(() =>
+          'Requested-slot backlog scheduling failed: invalid task state. '
+          'taskId=${task.id} taskType=${task.type.name} taskStatus=${task.status.name}');
+      return _unchangedResult(
+        input,
+        SchedulingNotice(
+          'Only backlog flexible tasks can be inserted.',
+          type: SchedulingNoticeType.noFit,
+          taskId: task.id,
+          issueCode: SchedulingIssueCode.invalidTaskState,
+        ),
+        operationCode: SchedulingOperationCode.insertBacklogTaskAtRequestedSlot,
+        outcomeCode: SchedulingOutcomeCode.invalidState,
+      );
+    }
+
+    final taskDuration = _durationFromMinutes(task.durationMinutes);
+    if (taskDuration == null) {
+      logger.warn(() =>
+          'Requested-slot backlog scheduling failed: missing positive duration. '
+          'taskId=${task.id} durationMinutes=${task.durationMinutes}');
+      return _unchangedResult(
+        input,
+        SchedulingNotice(
+          'Task needs a positive duration before scheduling.',
+          type: SchedulingNoticeType.noFit,
+          taskId: task.id,
+          issueCode: SchedulingIssueCode.missingDuration,
+        ),
+        operationCode: SchedulingOperationCode.insertBacklogTaskAtRequestedSlot,
+        outcomeCode: SchedulingOutcomeCode.invalidState,
+      );
+    }
+
+    if (!requestedStart.isBefore(requestedEnd)) {
+      logger.warn(() =>
+          'Requested-slot backlog scheduling failed: non-positive requested interval. '
+          'taskId=${task.id}');
+      return _unchangedResult(
+        input,
+        SchedulingNotice(
+          'Requested slot must have a positive duration.',
+          type: SchedulingNoticeType.noFit,
+          taskId: task.id,
+          issueCode: SchedulingIssueCode.nonPositiveDuration,
+        ),
+        operationCode: SchedulingOperationCode.insertBacklogTaskAtRequestedSlot,
+        outcomeCode: SchedulingOutcomeCode.invalidState,
+      );
+    }
+
+    final requestedInterval = TimeInterval(
+      start: requestedStart,
+      end: requestedEnd,
+      label: task.id,
+    );
+    if (requestedInterval.duration != taskDuration) {
+      logger.warn(() =>
+          'Requested-slot backlog scheduling failed: duration mismatch. '
+          'taskId=${task.id} taskDurationMinutes=${taskDuration.inMinutes} '
+          'requestedDurationMinutes=${requestedInterval.duration.inMinutes}');
+      return _unchangedResult(
+        input,
+        SchedulingNotice(
+          'Requested slot no longer matches the task estimate.',
+          type: SchedulingNoticeType.noFit,
+          taskId: task.id,
+          issueCode: SchedulingIssueCode.durationMismatch,
+        ),
+        operationCode: SchedulingOperationCode.insertBacklogTaskAtRequestedSlot,
+        outcomeCode: SchedulingOutcomeCode.invalidState,
+      );
+    }
+
+    if (!input.window.contains(requestedInterval)) {
+      logger.warn(() =>
+          'Requested-slot backlog scheduling failed: slot outside window. '
+          'taskId=${task.id}');
+      return _unchangedResult(
+        input,
+        SchedulingNotice(
+          'Requested slot is outside the planning window.',
+          type: SchedulingNoticeType.overflow,
+          taskId: task.id,
+          issueCode: SchedulingIssueCode.noAvailableSlot,
+        ),
+        operationCode: SchedulingOperationCode.insertBacklogTaskAtRequestedSlot,
+        outcomeCode: SchedulingOutcomeCode.noSlot,
+      );
+    }
+
+    final placement = _planBacklogInsertionAtRequestedSlot(
+      input: input,
+      task: task,
+      requestedInterval: requestedInterval,
+    );
+    if (placement == null) {
+      logger.warn(() =>
+          'Requested-slot backlog scheduling failed: slot blocked or queue overflowed. '
+          'taskId=${task.id}');
+      return _unchangedResult(
+        input,
+        SchedulingNotice(
+          'Requested slot is no longer open.',
+          type: SchedulingNoticeType.overflow,
+          taskId: task.id,
+          issueCode: SchedulingIssueCode.noAvailableSlot,
+        ),
+        operationCode: SchedulingOperationCode.insertBacklogTaskAtRequestedSlot,
+        outcomeCode: SchedulingOutcomeCode.noSlot,
+      );
+    }
+
+    return _applyPlacement(
+      input: input,
+      insertedTask: task,
+      placement: placement,
+      updatedAt: updatedAt ?? clock.now(),
+      operationCode: SchedulingOperationCode.insertBacklogTaskAtRequestedSlot,
+    );
+  }
+
   /// Push a planned flexible task to the next available slot today.
   ///
   /// The selected task moves after its current slot. Planned flexible tasks
@@ -803,6 +961,88 @@ _BacklogInsertionPlan? _planBacklogInsertion({
   return _BacklogInsertionPlan(placements: placements);
 }
 
+/// Plan a backlog insertion that must start at [requestedInterval].
+///
+/// Flexible tasks ending before the requested interval remain fixed. Flexible
+/// tasks that overlap or follow the requested interval join the queue after the
+/// inserted task and may move later to preserve an exact selected slot.
+_BacklogInsertionPlan? _planBacklogInsertionAtRequestedSlot({
+  required SchedulingInput input,
+  required Task task,
+  required TimeInterval requestedInterval,
+}) {
+  final fixedBlocks = <TimeInterval>[
+    ...input.blockedIntervals,
+  ];
+  final queue = <_PlacementItem>[];
+
+  final scheduledFlexibleTasks = input.movablePlannedFlexibleTasks
+      .where((flexibleTask) => flexibleTask.id != task.id)
+      .toList(growable: false)
+    ..sort((a, b) {
+      final aStart = a.scheduledStart ?? input.window.end;
+      final bStart = b.scheduledStart ?? input.window.end;
+
+      return aStart.compareTo(bStart);
+    });
+
+  for (final flexibleTask in scheduledFlexibleTasks) {
+    final interval = _scheduledIntervalFor(flexibleTask);
+    if (interval == null) {
+      continue;
+    }
+
+    final startsBeforeWindow = interval.start.isBefore(input.window.start);
+    final startsAfterWindow = interval.start.isAfter(input.window.end) ||
+        interval.start.isAtSameMomentAs(input.window.end);
+    final endsBeforeRequested =
+        interval.end.isBefore(requestedInterval.start) ||
+            interval.end.isAtSameMomentAs(requestedInterval.start);
+
+    if (startsBeforeWindow || startsAfterWindow || endsBeforeRequested) {
+      fixedBlocks.add(interval);
+      continue;
+    }
+
+    queue.add(
+      _PlacementItem(
+        task: flexibleTask,
+        duration: interval.duration,
+        earliestStart: interval.start,
+      ),
+    );
+  }
+
+  fixedBlocks.sort((a, b) => a.start.compareTo(b.start));
+  if (fixedBlocks.any((interval) => interval.overlaps(requestedInterval))) {
+    return null;
+  }
+
+  var cursor = requestedInterval.end;
+  final placements = <String, TimeInterval>{
+    task.id: requestedInterval,
+  };
+
+  for (final item in queue) {
+    final earliestStart = _laterOf(cursor, item.earliestStart);
+    final interval = _firstOpenIntervalFrom(
+      earliestStart: earliestStart,
+      windowEnd: input.window.end,
+      duration: item.duration,
+      blocked: fixedBlocks,
+    );
+
+    if (interval == null) {
+      return null;
+    }
+
+    placements[item.task.id] = interval;
+    cursor = interval.end;
+  }
+
+  return _BacklogInsertionPlan(placements: placements);
+}
+
 /// Plan the "push later today" behavior for one flexible task.
 ///
 /// Items before the pushed task's current end are fixed. The pushed task starts
@@ -996,6 +1236,8 @@ SchedulingResult _applyPlacement({
   required Task insertedTask,
   required _BacklogInsertionPlan placement,
   required DateTime updatedAt,
+  SchedulingOperationCode operationCode =
+      SchedulingOperationCode.insertBacklogTaskIntoNextAvailableSlot,
 }) {
   final changes = <SchedulingChange>[];
   final notices = <SchedulingNotice>[];
@@ -1028,8 +1270,7 @@ SchedulingResult _applyPlacement({
     final updatedTask = _applySchedulingActivity(
       originalTask: task,
       updatedTask: placedTask,
-      operationCode:
+      operationCode: operationCode,
-          SchedulingOperationCode.insertBacklogTaskIntoNextAvailableSlot,
       activityCode: isInsertedTask
           ? TaskActivityCode.restoredFromBacklog
           : TaskActivityCode.automaticallyPushed,
@@ -1075,8 +1316,7 @@ SchedulingResult _applyPlacement({
       'noticeCount=${notices.length}');
   return SchedulingResult(
     tasks: List<Task>.unmodifiable(updatedTasks),
-    operationCode:
+    operationCode: operationCode,
-        SchedulingOperationCode.insertBacklogTaskIntoNextAvailableSlot,
     outcomeCode: SchedulingOutcomeCode.success,
     notices: List<SchedulingNotice>.unmodifiable(notices),
     changes: List<SchedulingChange>.unmodifiable(changes),

packages/scheduler_core/test/application_commands_test.dart

@@ -113,6 +113,97 @@ void main() {
       ]);
     });
 
+    test('schedules backlog item at suggested slot and persists movement',
+        () async {
+      final backlog = task(
+        id: 'suggested',
+        title: 'Suggested',
+        type: TaskType.flexible,
+        status: TaskStatus.backlog,
+        createdAt: createdAt,
+        durationMinutes: 30,
+      );
+      final planned = task(
+        id: 'planned',
+        title: 'Planned',
+        type: TaskType.flexible,
+        status: TaskStatus.planned,
+        createdAt: createdAt,
+        start: DateTime.utc(2026, 6, 25, 9),
+        end: DateTime.utc(2026, 6, 25, 9, 30),
+      );
+      final store = storeWithSettings(tasks: [backlog, planned]);
+
+      final result = await commands(store).scheduleBacklogItemAtSuggestedSlot(
+        context: appContext('schedule-suggested', DateTime.utc(2026, 6, 25, 8)),
+        localDate: day,
+        taskId: backlog.id,
+        scheduledStart: DateTime.utc(2026, 6, 25, 9),
+        scheduledEnd: DateTime.utc(2026, 6, 25, 9, 30),
+        expectedUpdatedAt: backlog.updatedAt,
+      );
+
+      expect(result.isSuccess, isTrue);
+      expect(
+        result.requireValue.schedulingResult!.operationCode,
+        SchedulingOperationCode.insertBacklogTaskAtRequestedSlot,
+      );
+      expect(
+        taskById(store.currentTasks, 'suggested').scheduledStart,
+        DateTime.utc(2026, 6, 25, 9),
+      );
+      expect(
+        taskById(store.currentTasks, 'suggested').scheduledEnd,
+        DateTime.utc(2026, 6, 25, 9, 30),
+      );
+      expect(
+        taskById(store.currentTasks, 'planned').scheduledStart,
+        DateTime.utc(2026, 6, 25, 9, 30),
+      );
+      expect(store.currentTaskActivities.map((activity) => activity.code), [
+        TaskActivityCode.restoredFromBacklog,
+        TaskActivityCode.automaticallyPushed,
+      ]);
+    });
+
+    test('suggested slot command rejects a blocked interval', () async {
+      final backlog = task(
+        id: 'blocked-suggested',
+        title: 'Blocked suggested',
+        type: TaskType.flexible,
+        status: TaskStatus.backlog,
+        createdAt: createdAt,
+        durationMinutes: 30,
+      );
+      final requiredTask = task(
+        id: 'appointment',
+        title: 'Appointment',
+        type: TaskType.inflexible,
+        status: TaskStatus.planned,
+        createdAt: createdAt,
+        start: DateTime.utc(2026, 6, 25, 10),
+        end: DateTime.utc(2026, 6, 25, 10, 30),
+      );
+      final store = storeWithSettings(tasks: [backlog, requiredTask]);
+
+      final result = await commands(store).scheduleBacklogItemAtSuggestedSlot(
+        context: appContext(
+          'schedule-blocked-suggested',
+          DateTime.utc(2026, 6, 25, 8),
+        ),
+        localDate: day,
+        taskId: backlog.id,
+        scheduledStart: DateTime.utc(2026, 6, 25, 10),
+        scheduledEnd: DateTime.utc(2026, 6, 25, 10, 30),
+        expectedUpdatedAt: backlog.updatedAt,
+      );
+
+      expect(result.failure!.code, ApplicationFailureCode.noSlot);
+      expect(taskById(store.currentTasks, backlog.id), backlog);
+      expect(store.currentTaskActivities, isEmpty);
+      expect(store.currentOperations, isEmpty);
+    });
+
     test('schedules backlog item after duration is supplied', () async {
       final backlog = Task.quickCapture(
         id: 'backlog',

packages/scheduler_core/test/application_management_test.dart

@@ -197,9 +197,11 @@ void main() {
         addedLabel: 'Added today',
         tags: const ['finance'],
         projectOptions: result.projectOptions,
-        suggestedSlots: const [
+        suggestedSlots: [
           SuggestedSlotReadModel(
             id: 'today-1',
+            startUtc: DateTime.utc(2026, 6, 25, 14),
+            endUtc: DateTime.utc(2026, 6, 25, 15),
             localDateLabel: 'Today',
             startText: '2:00 PM',
             endText: '3:00 PM',
@@ -655,6 +657,14 @@ void main() {
 
       expect(detail.suggestedSlots.first.startText, '10:00 AM');
       expect(detail.suggestedSlots.first.endText, '10:30 AM');
+      expect(
+        detail.suggestedSlots.first.startUtc,
+        DateTime.utc(2026, 6, 25, 10),
+      );
+      expect(
+        detail.suggestedSlots.first.endUtc,
+        DateTime.utc(2026, 6, 25, 10, 30),
+      );
       expect(detail.suggestedSlots.first.fitLabel, 'Great Fit');
       expect(detail.suggestedSlotUnavailableReason, isNull);
       expect(store.currentTasks, beforeTasks);

packages/scheduler_core/test/scheduling_engine_test.dart

@@ -1392,6 +1392,80 @@ void main() {
       ]);
     });
 
+    test('insert backlog task at requested slot preserves selected interval',
+        () {
+      final backlogTask = Task.quickCapture(
+        id: 'backlog-1',
+        title: 'Start laundry',
+        createdAt: now,
+      ).copyWith(durationMinutes: 15);
+      final plannedFlexible = flexibleTask().copyWith(
+        id: 'flexible-1',
+        durationMinutes: 30,
+        scheduledStart: DateTime(2026, 6, 19, 13, 15),
+        scheduledEnd: DateTime(2026, 6, 19, 13, 45),
+      );
+      final result = engine.insertBacklogTaskAtRequestedSlot(
+        input: SchedulingInput(
+          tasks: [backlogTask, plannedFlexible],
+          window: SchedulingWindow(
+            start: DateTime(2026, 6, 19, 13),
+            end: DateTime(2026, 6, 19, 14),
+          ),
+        ),
+        taskId: 'backlog-1',
+        requestedStart: DateTime(2026, 6, 19, 13, 15),
+        requestedEnd: DateTime(2026, 6, 19, 13, 30),
+        updatedAt: now,
+      );
+      final inserted = taskById(result.tasks, 'backlog-1');
+      final pushed = taskById(result.tasks, 'flexible-1');
+
+      expect(result.operationCode,
+          SchedulingOperationCode.insertBacklogTaskAtRequestedSlot);
+      expect(inserted.scheduledStart, DateTime(2026, 6, 19, 13, 15));
+      expect(inserted.scheduledEnd, DateTime(2026, 6, 19, 13, 30));
+      expect(pushed.scheduledStart, DateTime(2026, 6, 19, 13, 30));
+      expect(pushed.scheduledEnd, DateTime(2026, 6, 19, 14));
+      expect(result.changes.map((change) => change.taskId), [
+        'backlog-1',
+        'flexible-1',
+      ]);
+    });
+
+    test('insert backlog task at requested slot rejects blocked time', () {
+      final backlogTask = Task.quickCapture(
+        id: 'backlog-1',
+        title: 'Start laundry',
+        createdAt: now,
+      ).copyWith(durationMinutes: 15);
+      final inflexibleTask = flexibleTask().copyWith(
+        id: 'inflexible-1',
+        type: TaskType.inflexible,
+        scheduledStart: DateTime(2026, 6, 19, 13, 15),
+        scheduledEnd: DateTime(2026, 6, 19, 13, 30),
+      );
+      final result = engine.insertBacklogTaskAtRequestedSlot(
+        input: SchedulingInput(
+          tasks: [backlogTask, inflexibleTask],
+          window: SchedulingWindow(
+            start: DateTime(2026, 6, 19, 13),
+            end: DateTime(2026, 6, 19, 14),
+          ),
+        ),
+        taskId: 'backlog-1',
+        requestedStart: DateTime(2026, 6, 19, 13, 15),
+        requestedEnd: DateTime(2026, 6, 19, 13, 30),
+        updatedAt: now,
+      );
+
+      expect(result.outcomeCode, SchedulingOutcomeCode.noSlot);
+      expect(result.changes, isEmpty);
+      expect(
+          result.notices.single.issueCode, SchedulingIssueCode.noAvailableSlot);
+      expect(result.tasks, [backlogTask, inflexibleTask]);
+    });
+
     test('insert backlog task skips locked time', () {
       final backlogTask = Task.quickCapture(
         id: 'backlog-1',