feat(todo): reminders at a time of their own planned and set in a task's sheet, durations in its date sheet

planReminders plans each reminder at a time of its own of an open task,
whatever its date, under an ID of its own; the notification says
"Reminder" for a task without a time. The task's sheet always has its
reminders' row: those before its time where it has one, those at a time
of their own each with its remove button and "Remind at a time" (a day,
then a time), the permission asked as a first one is chosen. The date
sheet sets a duration once there is a time (none, 15 minutes to 4
hours, as Todoist's), a time cleared taking it with it. Recorded as
ADR 0033, D18 (the developer's, 3 Nov 2026).

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/l10n/app_de.arb

@@ -124,6 +124,15 @@
   "remindersChannel": "Erinnerungen an Aufgaben",
   "remindersNotAllowed": "Benachrichtigungen sind für Halkyon Todo aus: Erinnerungen erscheinen, sobald du sie in den Systemeinstellungen erlaubst.",
   "remindersOnThisDevice": "Erinnerungen kommen auf jedem deiner Geräte, das deine Aufgaben öffnet.",
+  "reminderBody": "Erinnerung",
+  "remindersAtTimes": "Zu einer eigenen Uhrzeit",
+  "reminderAddTime": "Zu einer Uhrzeit erinnern",
+  "reminderRemove": "Erinnerung entfernen",
+  "durationTitle": "Dauer",
+  "durationNone": "Keine Dauer",
+  "durationHours": "{hours} Std.",
+  "durationMinutes": "{minutes} Min.",
+  "durationHoursMinutes": "{hours} Std. {minutes} Min.",
   "weekPrevious": "Vorige Woche",
   "weekNext": "Folgende Woche",
   "searchTitle": "Suchen",

apps/todo/halkyon_todo_flutter/lib/l10n/app_en.arb

@@ -343,6 +343,39 @@
   "remindersChannel": "Task reminders",
   "remindersNotAllowed": "Notifications are off for Halkyon Todo: reminders show once you allow them in the system's settings.",
   "remindersOnThisDevice": "Reminders come on each of your devices that opens your tasks.",
+  "reminderBody": "Reminder",
+  "remindersAtTimes": "At a time of their own",
+  "reminderAddTime": "Remind at a time",
+  "reminderRemove": "Remove the reminder",
+  "durationTitle": "Duration",
+  "durationNone": "No duration",
+  "durationHours": "{hours} h",
+  "@durationHours": {
+    "placeholders": {
+      "hours": {
+        "type": "int"
+      }
+    }
+  },
+  "durationMinutes": "{minutes} min",
+  "@durationMinutes": {
+    "placeholders": {
+      "minutes": {
+        "type": "int"
+      }
+    }
+  },
+  "durationHoursMinutes": "{hours} h {minutes} min",
+  "@durationHoursMinutes": {
+    "placeholders": {
+      "hours": {
+        "type": "int"
+      },
+      "minutes": {
+        "type": "int"
+      }
+    }
+  },
   "weekPrevious": "Previous week",
   "weekNext": "Following week",
   "searchTitle": "Search",

apps/todo/halkyon_todo_flutter/lib/l10n/app_localizations.dart

@@ -844,6 +844,60 @@ abstract class AppLocalizations {
   /// **'Reminders come on each of your devices that opens your tasks.'**
   String get remindersOnThisDevice;
 
+  /// No description provided for @reminderBody.
+  ///
+  /// In en, this message translates to:
+  /// **'Reminder'**
+  String get reminderBody;
+
+  /// No description provided for @remindersAtTimes.
+  ///
+  /// In en, this message translates to:
+  /// **'At a time of their own'**
+  String get remindersAtTimes;
+
+  /// No description provided for @reminderAddTime.
+  ///
+  /// In en, this message translates to:
+  /// **'Remind at a time'**
+  String get reminderAddTime;
+
+  /// No description provided for @reminderRemove.
+  ///
+  /// In en, this message translates to:
+  /// **'Remove the reminder'**
+  String get reminderRemove;
+
+  /// No description provided for @durationTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Duration'**
+  String get durationTitle;
+
+  /// No description provided for @durationNone.
+  ///
+  /// In en, this message translates to:
+  /// **'No duration'**
+  String get durationNone;
+
+  /// No description provided for @durationHours.
+  ///
+  /// In en, this message translates to:
+  /// **'{hours} h'**
+  String durationHours(int hours);
+
+  /// No description provided for @durationMinutes.
+  ///
+  /// In en, this message translates to:
+  /// **'{minutes} min'**
+  String durationMinutes(int minutes);
+
+  /// No description provided for @durationHoursMinutes.
+  ///
+  /// In en, this message translates to:
+  /// **'{hours} h {minutes} min'**
+  String durationHoursMinutes(int hours, int minutes);
+
   /// No description provided for @weekPrevious.
   ///
   /// In en, this message translates to:

apps/todo/halkyon_todo_flutter/lib/l10n/app_localizations_de.dart

@@ -527,6 +527,39 @@ class AppLocalizationsDe extends AppLocalizations {
   String get remindersOnThisDevice =>
       'Erinnerungen kommen auf jedem deiner Geräte, das deine Aufgaben öffnet.';
 
+  @override
+  String get reminderBody => 'Erinnerung';
+
+  @override
+  String get remindersAtTimes => 'Zu einer eigenen Uhrzeit';
+
+  @override
+  String get reminderAddTime => 'Zu einer Uhrzeit erinnern';
+
+  @override
+  String get reminderRemove => 'Erinnerung entfernen';
+
+  @override
+  String get durationTitle => 'Dauer';
+
+  @override
+  String get durationNone => 'Keine Dauer';
+
+  @override
+  String durationHours(int hours) {
+    return '$hours Std.';
+  }
+
+  @override
+  String durationMinutes(int minutes) {
+    return '$minutes Min.';
+  }
+
+  @override
+  String durationHoursMinutes(int hours, int minutes) {
+    return '$hours Std. $minutes Min.';
+  }
+
   @override
   String get weekPrevious => 'Vorige Woche';
 

apps/todo/halkyon_todo_flutter/lib/l10n/app_localizations_en.dart

@@ -527,6 +527,39 @@ class AppLocalizationsEn extends AppLocalizations {
   String get remindersOnThisDevice =>
       'Reminders come on each of your devices that opens your tasks.';
 
+  @override
+  String get reminderBody => 'Reminder';
+
+  @override
+  String get remindersAtTimes => 'At a time of their own';
+
+  @override
+  String get reminderAddTime => 'Remind at a time';
+
+  @override
+  String get reminderRemove => 'Remove the reminder';
+
+  @override
+  String get durationTitle => 'Duration';
+
+  @override
+  String get durationNone => 'No duration';
+
+  @override
+  String durationHours(int hours) {
+    return '$hours h';
+  }
+
+  @override
+  String durationMinutes(int minutes) {
+    return '$minutes min';
+  }
+
+  @override
+  String durationHoursMinutes(int hours, int minutes) {
+    return '$hours h $minutes min';
+  }
+
   @override
   String get weekPrevious => 'Previous week';