fix(alarms): Kanban moves no longer re-arm due alarms of open tasks

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/storage/recurrence_test.go

@@ -139,6 +139,44 @@ func TestAlarmResetsOnNewDueDateOrReopen(t *testing.T) {
 	}
 }
 
+// A Kanban move sends every task of the touched columns: only a task that goes from done back to open
+// may get its due alarm again, the others must not be notified a second time
+func TestKanbanMoveKeepsSentAlarms(t *testing.T) {
+	store, err := NewStore(filepath.Join(t.TempDir(), "kanban-alarm.db"))
+	if err != nil {
+		t.Fatalf("NewStore: %v", err)
+	}
+	defer store.Close()
+	u, _ := store.CreateUser("anna@example.com", "hash", "Anna", "member")
+	tl, _ := store.CreateTaskList(u.ID, "", "", "Haushalt", "🏠", "")
+	task, _ := store.CreateThoughtWithDetails(u.ID, "Heizung entlüften", "normal", "manual", "2026-10-31 09:00", tl.ID, "todo", "")
+	_, _ = store.UpdateThoughtTriage(u.ID, task.ID, "keep", "task", "", "", tl.ID)
+	sent := func() bool {
+		th, _ := store.GetThoughtByID(u.ID, task.ID)
+		return th.AlarmSent
+	}
+	move := func(status string) {
+		if err := store.ReorderTasks(tl.ID, []domain.ThoughtReorderItem{{ID: task.ID, SortOrder: 0, KanbanStatus: &status}}); err != nil {
+			t.Fatalf("ReorderTasks: %v", err)
+		}
+	}
+
+	_ = store.MarkTaskAlarmSent(task.ID)
+	move("in_progress")
+	move("todo")
+	if !sent() {
+		t.Errorf("moving an open task between columns must not re-arm its alarm")
+	}
+	move("done")
+	if !sent() {
+		t.Errorf("completing keeps the flag")
+	}
+	move("todo")
+	if sent() {
+		t.Errorf("reopening via the board must re-arm the alarm")
+	}
+}
+
 func TestAlarmGivesUpAfterThreeFailedRuns(t *testing.T) {
 	store, err := NewStore(filepath.Join(t.TempDir(), "alarmfail.db"))
 	if err != nil {

internal/storage/thoughts.go

@@ -243,10 +243,13 @@ func (s *Store) ReorderTasks(taskListID string, items []domain.ThoughtReorderIte
 					completed = append(completed, it.ID)
 				}
 			}
+			// Only a reopened task (done -> open) gets its due alarm again. A Kanban move sends every task
+			// of the touched columns, so resetting all open ones re-sent "due today" for each of them.
+			// (is_completed in the CASE is still the value before this UPDATE.)
 			_, err = tx.Exec(
 				`UPDATE thoughts SET sort_order = ?, kanban_status = ?, is_completed = ?,
-				 alarm_sent = CASE WHEN ? = 0 THEN 0 ELSE alarm_sent END,
-				 alarm_failures = CASE WHEN ? = 0 THEN 0 ELSE alarm_failures END WHERE id = ?`,
+				 alarm_sent = CASE WHEN ? = 0 AND is_completed = 1 THEN 0 ELSE alarm_sent END,
+				 alarm_failures = CASE WHEN ? = 0 AND is_completed = 1 THEN 0 ELSE alarm_failures END WHERE id = ?`,
 				it.SortOrder, *it.KanbanStatus, isCompleted, isCompleted, isCompleted, it.ID,
 			)
 		} else {