fix(todo): a snoozed reminder back at the minute too (ADR 0033, D31)

A snooze was scheduled inexact, as snoozes are minutes long; an idle phone
may bring an inexact alarm back later than the snooze lasts. With
USE_EXACT_ALARM (D31) Android lets the app wake at the minute, so a
snoozed reminder is exactAllowWhileIdle too wherever the plugin says it
can schedule exactly, and inexact where it can't (Android 12 with the
permission taken back).

Whats-New: A snoozed reminder comes back on the minute.
Whats-New-De: Eine geschlummerte Erinnerung kommt pünktlich wieder.

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/reminder/data/system_reminder_gateway.dart

@@ -54,14 +54,25 @@ Future<void> _scheduleSnoozed(
     return;
   }
   try {
+    // Back at the minute too, where Android lets the app wake then
+    // (USE_EXACT_ALARM, D31): an inexact alarm may come many minutes late
+    // while the phone idles, longer than a short snooze lasts.
+    final exact =
+        await plugin
+            .resolvePlatformSpecificImplementation<
+              AndroidFlutterLocalNotificationsPlugin
+            >()
+            ?.canScheduleExactNotifications() ??
+        true;
     await plugin.zonedSchedule(
       id: back.notice.id,
       title: back.notice.title,
       body: back.notice.body,
       scheduledDate: tz.TZDateTime.from(back.notice.at.toUtc(), tz.UTC),
       notificationDetails: details,
-      // Snoozed for minutes, not to the minute: no exact alarm needed.
-      androidScheduleMode: AndroidScheduleMode.inexactAllowWhileIdle,
+      androidScheduleMode: exact
+          ? AndroidScheduleMode.exactAllowWhileIdle
+          : AndroidScheduleMode.inexactAllowWhileIdle,
       payload: back.payload,
     );
   } on Object catch (error) {

docs/adr/0033-halkyon-todo.md

@@ -594,7 +594,9 @@ The developer's review of 4 Nov 2026, again beside Todoist's screens.
     declared for Android 12 and 12L, which don't know the other, up to API 32 alone
     (`test/android/exact_alarms_test.dart`). `AlarmManager.canScheduleExactAlarms` is
     true with either, so the plugin's `canScheduleExactNotifications` is, and reminders
-    are `exactAllowWhileIdle`. *Alternatives:* leading the person to *Alarms &
+    are `exactAllowWhileIdle`, a snoozed reminder too (the developer's, as it had been
+    inexact while snoozes were minutes long; an idle phone may bring an inexact one later
+    than the snooze lasts). *Alternatives:* leading the person to *Alarms &
     reminders* (one more permission to ask and explain, which most would never find
     again once refused), staying inexact (reminders minutes late, which a reminder at a
     time can't be). Google Play reviews `USE_EXACT_ALARM` against that purpose; Todo is