feat(todo): the Inbox's Calendar as an Agenda or 3-day

As Todoist's Display in the Inbox: once its layout is Calendar, a row
"Layout: Agenda" opens a small choice of Agenda or 3-day; 3-day shows the
Inbox's tasks in Upcoming's HourGrid, whatever the window's width, where a
tap on an hour adds to the Inbox. Kept as the project's other Display
choices, in its sealed view (`calendarLayout`, written only when it isn't
the Agenda; a value this version doesn't know reads as the Agenda).
Another project's Calendar stays the agenda (or the month), as Todoist
offers the choice in the Inbox alone.

Whats-New: The Inbox's Calendar can show three days of hours: Display, Layout, 3-day.
Whats-New-De: Der Kalender des Eingangs kann drei Tage mit ihren Stunden zeigen: Anzeige, Layout, 3 Tage.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/todo/halkyon_todo_flutter/lib/src/feature/project/data/project_payload.dart

@@ -49,6 +49,8 @@ Map<String, Object?> encodeView(ProjectView view) => {
   if (view.layout != ProjectLayout.list) 'layout': view.layout.name,
   if (view.completed) 'completed': true,
   if (view.occurrences) 'occurrences': true,
+  if (view.calendarLayout != CalendarLayout.agenda)
+    'calendarLayout': view.calendarLayout.name,
   if (view.grouping != TaskGrouping.none) 'grouping': view.grouping.name,
   if (view.sorting != TaskSorting.manual) 'sorting': view.sorting.name,
   if (view.date != DayRange.all) 'date': view.date.name,
@@ -78,6 +80,11 @@ ProjectView decodeView(Object? json) {
     layout: named(ProjectLayout.values, 'layout', ProjectLayout.list),
     completed: json['completed'] == true,
     occurrences: json['occurrences'] == true,
+    calendarLayout: named(
+      CalendarLayout.values,
+      'calendarLayout',
+      CalendarLayout.agenda,
+    ),
     grouping: named(TaskGrouping.values, 'grouping', TaskGrouping.none),
     sorting: named(TaskSorting.values, 'sorting', TaskSorting.manual),
     date: named(DayRange.values, 'date', DayRange.all),

apps/todo/halkyon_todo_flutter/lib/src/feature/project/model/project_view.dart

@@ -12,6 +12,14 @@ enum ProjectLayout() {
   table,
 }
 
+/// How the Inbox lays out its Calendar (the developer's review, 7 Nov 2026,
+/// as Todoist's Display offers it in the Inbox alone): day under day, or
+/// three days of hours side by side, as Upcoming's.
+enum CalendarLayout() {
+  agenda,
+  threeDay,
+}
+
 /// A column of a project's table (D36); the task's stands among them and
 /// moves as they do, but can't be hidden.
 enum TaskColumn() {
@@ -111,6 +119,9 @@ final class const ProjectView({
 
   /// Whether a Calendar shows repeating tasks on their later days too.
   final bool occurrences = false,
+
+  /// How a Calendar lays out its days, the Inbox's alone choosing.
+  final CalendarLayout calendarLayout = CalendarLayout.agenda,
   final TaskGrouping grouping = TaskGrouping.none,
   final TaskSorting sorting = TaskSorting.manual,
   final DayRange date = DayRange.all,
@@ -230,6 +241,7 @@ final class const ProjectView({
     ProjectLayout? layout,
     bool? completed,
     bool? occurrences,
+    CalendarLayout? calendarLayout,
     TaskGrouping? grouping,
     TaskSorting? sorting,
     DayRange? date,
@@ -244,6 +256,7 @@ final class const ProjectView({
     layout: layout ?? this.layout,
     completed: completed ?? this.completed,
     occurrences: occurrences ?? this.occurrences,
+    calendarLayout: calendarLayout ?? this.calendarLayout,
     grouping: grouping ?? this.grouping,
     sorting: sorting ?? this.sorting,
     date: date ?? this.date,
@@ -261,6 +274,7 @@ final class const ProjectView({
     layout,
     completed,
     occurrences,
+    calendarLayout,
     grouping,
     sorting,
     date,

apps/todo/halkyon_todo_flutter/lib/src/feature/project/widget/display_sheet.dart

@@ -100,6 +100,37 @@ DisplayTarget projectDisplay(String projectId) {
             (todo) => write(todo, state, view.copyWith(layout: layout)),
           ),
         ),
+        // The Inbox's Calendar as an agenda or three days of hours, as
+        // Todoist's Display offers in the Inbox alone (the developer's
+        // review, 7 Nov 2026): a project's quick add from the hours would
+        // add to the Inbox.
+        if (view.layout == ProjectLayout.calendar &&
+            (state.projectOf(projectId)?.inbox ?? false))
+          ListTile(
+            key: calendarLayoutKey,
+            leading: const Icon(LucideIcons.columns3),
+            title: Text(l10n.layoutTitle),
+            subtitle: Text(calendarLayoutText(l10n, view.calendarLayout)),
+            onTap: () async {
+              if (await pickOne(
+                    context,
+                    l10n.layoutTitle,
+                    CalendarLayout.values,
+                    view.calendarLayout,
+                    (layout) => calendarLayoutText(l10n, layout),
+                  )
+                  case final layout? when context.mounted) {
+                final now = context.read<TodoCubit>().state;
+                await apply(
+                  (todo) => write(
+                    todo,
+                    now,
+                    viewOf(now).copyWith(calendarLayout: layout),
+                  ),
+                );
+              }
+            },
+          ),
         if (view.layout == ProjectLayout.table)
           ListTile(
             leading: const Icon(LucideIcons.columns3),
@@ -122,6 +153,16 @@ DisplayTarget projectDisplay(String projectId) {
   );
 }
 
+/// The key of the Inbox's Calendar's row choosing Agenda or 3-day.
+const calendarLayoutKey = ValueKey('display-calendar-layout');
+
+/// [layout]'s name, as Upcoming's Display names its own.
+String calendarLayoutText(AppLocalizations l10n, CalendarLayout layout) =>
+    switch (layout) {
+      CalendarLayout.agenda => l10n.layoutAgenda,
+      CalendarLayout.threeDay => l10n.layoutThreeDay,
+    };
+
 /// Upcoming's Display (D17, as Todoist's): agenda or 3-day, in the grid
 /// what tasks are coloured by, done tasks, future occurrences, sorting
 /// (smart: by time, then priority), and the filters by deadline, priority

apps/todo/halkyon_todo_flutter/lib/src/feature/project/widget/project_calendar_view.dart

@@ -4,11 +4,13 @@ import 'package:halkyon_todo_flutter/l10n/app_localizations.dart';
 import 'package:halkyon_todo_flutter/src/feature/project/model/project_calendar.dart';
 import 'package:halkyon_todo_flutter/src/feature/project/model/project_view.dart';
 import 'package:halkyon_todo_flutter/src/feature/project/widget/month_grid.dart';
+import 'package:halkyon_todo_flutter/src/feature/settings/model/todo_settings.dart';
 import 'package:halkyon_todo_flutter/src/feature/task/bloc/todo_cubit.dart';
 import 'package:halkyon_todo_flutter/src/feature/task/model/task.dart';
 import 'package:halkyon_todo_flutter/src/feature/task/model/task_views.dart';
 import 'package:halkyon_todo_flutter/src/feature/task/widget/task_tile.dart';
 import 'package:halkyon_todo_flutter/src/tabs/day_agenda.dart';
+import 'package:halkyon_todo_flutter/src/tabs/hour_grid.dart';
 import 'package:halkyon_todo_flutter/src/tabs/week_strip.dart';
 import 'package:halkyon_ui/halkyon_ui.dart';
 import 'package:lucide_icons_flutter/lucide_icons.dart';
@@ -19,7 +21,8 @@ import 'package:material_ui/material_ui.dart';
 /// Display keeps, sub-tasks too, a day's in its sorting (by time where it
 /// sorts by hand); where it asks, repeating tasks also on their later days.
 /// *No date* beside the month opens the tasks without one. From
-/// [ProjectCalendarView.monthWidth] on, a month instead ([MonthGrid]).
+/// [ProjectCalendarView.monthWidth] on, a month instead ([MonthGrid]). The
+/// Inbox's, where its Display asks, three days of hours ([HourGrid]).
 class const ProjectCalendarView({
   required final String projectId,
   required final ProjectView view,
@@ -69,6 +72,23 @@ class const ProjectCalendarView({
       child: Text(l10n.calendarNoDate),
     );
     final order = view.sorting == TaskSorting.manual ? byTime : view.compare;
+    ProjectCalendar calendarFor(int days) => calendarOf(
+      kept,
+      Day.of(clock.now()),
+      days: days,
+      occurrences: view.occurrences,
+      order: order,
+    );
+    // The Inbox's three days of hours, as Upcoming's (the developer's
+    // review, 7 Nov 2026), whatever the width.
+    if (view.calendarLayout == CalendarLayout.threeDay &&
+        (state.projectOf(projectId)?.inbox ?? false)) {
+      return HourGrid(
+        foot: 0,
+        coloring: TaskColoring.priority,
+        calendarFor: calendarFor,
+      );
+    }
     return LayoutBuilder(
       builder: (context, constraints) => constraints.maxWidth >= monthWidth
           ? MonthGrid(
@@ -86,13 +106,7 @@ class const ProjectCalendarView({
           : DayAgenda(
               projectId: projectId,
               trailing: noDate,
-              calendarFor: (days) => calendarOf(
+              calendarFor: calendarFor,
-                kept,
-                Day.of(clock.now()),
-                days: days,
-                occurrences: view.occurrences,
-                order: order,
-              ),
             ),
     );
   }

apps/todo/halkyon_todo_flutter/test/app/todo_app_test.dart

@@ -28,6 +28,7 @@ import 'package:halkyon_todo_flutter/src/feature/project/data/project_repository
 import 'package:halkyon_todo_flutter/src/feature/project/model/project.dart';
 import 'package:halkyon_todo_flutter/src/feature/project/model/project_view.dart';
 import 'package:halkyon_todo_flutter/src/feature/project/model/stored_project.dart';
+import 'package:halkyon_todo_flutter/src/feature/project/widget/display_sheet.dart';
 import 'package:halkyon_todo_flutter/src/feature/project/widget/month_grid.dart';
 import 'package:halkyon_todo_flutter/src/feature/project/widget/project_board.dart';
 import 'package:halkyon_todo_flutter/src/feature/project/widget/project_calendar_view.dart';
@@ -1585,6 +1586,87 @@ void main() {
           expect(find.byTooltip('Mark as done'), findsOneWidget);
         });
 
+        testWidgets("the Inbox's Calendar is an Agenda or 3-day, as its "
+            'Display picks, kept in the Inbox; another project offers '
+            "neither (the developer's review, 7 Nov 2026, as Todoist's)", (
+          tester,
+        ) async {
+          await calendarOf(tester);
+          await seed(
+            tester,
+            TaskContent(
+              title: 'Dentist',
+              projectId: inbox(),
+              date: TaskDate(Day.of(DateTime.now()), time: 10 * 60),
+            ),
+          );
+          expect(find.byType(WeekStrip), findsOneWidget);
+
+          await display(tester);
+          expect(
+            find.descendant(
+              of: find.byKey(calendarLayoutKey),
+              matching: find.text('Agenda'),
+            ),
+            findsOneWidget,
+          );
+          await tester.tap(find.byKey(calendarLayoutKey));
+          await tester.pumpAndSettle();
+          await tester.tap(find.widgetWithText(ListTile, '3-day').last);
+          await tester.pumpAndSettle();
+          expect(
+            find.descendant(
+              of: find.byKey(calendarLayoutKey),
+              matching: find.text('3-day'),
+            ),
+            findsOneWidget,
+          );
+          await done(tester);
+
+          expect(find.byType(HourGrid), findsOneWidget);
+          expect(find.byType(WeekStrip), findsNothing);
+          expect(
+            find.descendant(
+              of: find.byType(HourGrid),
+              matching: find.text('Dentist'),
+            ),
+            findsOneWidget,
+          );
+          final projects = await tester.runAsync(
+            () => ProjectRepository(projectRows, keys).all(),
+          );
+          expect(
+            projects!
+                .singleWhere((project) => project.id == inbox())
+                .content
+                ?.view
+                .calendarLayout,
+            CalendarLayout.threeDay,
+          );
+
+          // A project of its own: its Calendar is the agenda alone.
+          await tester.runAsync(
+            () => ProjectRepository(projectRows, keys).save(
+              const ProjectContent(
+                name: 'Shopping',
+                position: 1,
+                view: ProjectView(
+                  layout: ProjectLayout.calendar,
+                  calendarLayout: CalendarLayout.threeDay,
+                ),
+              ),
+            ),
+          );
+          projectRows.bringRemoteChanges();
+          await goTab(tester, 'Browse');
+          await tester.tap(find.text('Shopping'));
+          await tester.pumpAndSettle();
+          expect(find.byType(WeekStrip), findsOneWidget);
+          expect(find.byType(HourGrid), findsNothing);
+          await display(tester);
+          expect(find.byKey(calendarLayoutKey), findsNothing);
+        });
+
         group('as a month on a wide window', () {
           /// Another day of today's month, so in its grid.
           Day otherDay() {

apps/todo/halkyon_todo_flutter/test/feature/project/project_payload_test.dart

@@ -61,6 +61,30 @@ void main() {
     });
   });
 
+  test(
+    "the Inbox's Calendar keeps its layout, Agenda or 3-day, written "
+    "only where it isn't the Agenda (the developer's review, 7 Nov 2026)",
+    () {
+      const threeDay = ProjectView(
+        layout: ProjectLayout.calendar,
+        calendarLayout: CalendarLayout.threeDay,
+      );
+      expect(encodeView(threeDay), {
+        'layout': 'calendar',
+        'calendarLayout': 'threeDay',
+      });
+      expect(decodeView(encodeView(threeDay)), threeDay);
+      expect(encodeView(const ProjectView(layout: ProjectLayout.calendar)), {
+        'layout': 'calendar',
+      });
+      expect(
+        decodeView({'layout': 'calendar', 'calendarLayout': 'week'}),
+        const ProjectView(layout: ProjectLayout.calendar),
+        reason: 'a layout this version does not know: the Agenda',
+      );
+    },
+  );
+
   test('a Display value this version does not know reads as at first', () {
     final read = decodeProject(
       json({