fix: let tasks be completed again and say when the server refuses #958

Ticking a task sent `progressUpdated`, which JSCalendar 2.0 dropped and
Stalwart rejects with `invalidProperties`, so the whole update failed.
The checkbox fired the toggle with `void`, so the task silently stayed
open.

- drop `progressUpdated` from the toggle patch, like webmail 6b30e91c
- flip the checkbox optimistically and put it back when the update
  fails
- show a "Failed to update task" alert with the server's reason

locales/rn/en.json

@@ -79,7 +79,8 @@
     },
     "tasks": {
       "add_placeholder": "Add a task…",
-      "add_time": "Add time"
+      "add_time": "Add time",
+      "update_error": "Failed to update task"
     }
   },
   "common": {

src/screens/CalendarScreen.tsx

@@ -609,6 +609,20 @@ export default function CalendarScreen() {
     [t],
   );
 
+  // The store flips the checkbox optimistically and reverts it when the
+  // server refuses; say so instead of leaving the user guessing.
+  const handleToggleTask = React.useCallback(
+    (id: string) => {
+      toggleTaskComplete(id).catch((err: unknown) => {
+        Alert.alert(
+          t('calendar.tasks.update_error', 'Failed to update task'),
+          err instanceof Error ? err.message : undefined,
+        );
+      });
+    },
+    [toggleTaskComplete, t],
+  );
+
   // Clone the event one day later and open it in the editor (webmail's
   // handleDuplicateFromDetail).
   const handleDuplicateFromDetail = React.useCallback(
@@ -942,7 +956,7 @@ export default function CalendarScreen() {
         onClose={() => { setTasksVisible(false); setTasksInitialId(null); }}
         onCreate={createTask}
         onUpdate={updateTask}
-        onToggle={toggleTaskComplete}
+        onToggle={handleToggleTask}
         onDelete={deleteTask}
       />
 

src/stores/__tests__/calendar-store.test.ts

@@ -638,4 +638,58 @@ describe('calendar-store', () => {
       expect(mockGetEvents).not.toHaveBeenCalled();
     });
   });
+
+  describe('toggleTaskComplete', () => {
+    it('completes a task without sending progressUpdated, which Stalwart rejects (#958)', async () => {
+      useCalendarStore.setState({
+        tasks: [{ id: 't1', '@type': 'Task', progress: 'needs-action' } as any],
+      });
+      mockUpdateEvent.mockResolvedValue(undefined);
+
+      await useCalendarStore.getState().toggleTaskComplete('t1');
+
+      expect(mockUpdateEvent).toHaveBeenCalledWith(
+        't1',
+        { progress: 'completed', percentComplete: 100 },
+        undefined,
+        undefined,
+      );
+      expect(useCalendarStore.getState().tasks[0].progress).toBe('completed');
+    });
+
+    it('reopens a completed task as needs-action on its owning account', async () => {
+      useCalendarStore.setState({
+        tasks: [{ id: 'acc-2:t1', originalId: 't1', accountId: 'acc-2', progress: 'completed' } as any],
+      });
+      mockUpdateEvent.mockResolvedValue(undefined);
+
+      await useCalendarStore.getState().toggleTaskComplete('acc-2:t1');
+
+      expect(mockUpdateEvent).toHaveBeenCalledWith(
+        't1',
+        { progress: 'needs-action', percentComplete: 0 },
+        undefined,
+        'acc-2',
+      );
+      expect(useCalendarStore.getState().tasks[0].progress).toBe('needs-action');
+    });
+
+    it('flips the task at once and reverts it when the server refuses', async () => {
+      useCalendarStore.setState({
+        tasks: [{ id: 't1', progress: 'needs-action', percentComplete: 20 } as any],
+      });
+      let reject!: (err: Error) => void;
+      mockUpdateEvent.mockReturnValue(new Promise((_, r) => { reject = r; }));
+
+      const pending = useCalendarStore.getState().toggleTaskComplete('t1');
+      expect(useCalendarStore.getState().tasks[0].progress).toBe('completed');
+
+      reject(new Error('invalidProperties'));
+      await expect(pending).rejects.toThrow('invalidProperties');
+      expect(useCalendarStore.getState().tasks[0]).toMatchObject({
+        progress: 'needs-action',
+        percentComplete: 20,
+      });
+    });
+  });
 });

src/stores/calendar-store.ts

@@ -712,12 +712,22 @@ export const useCalendarStore = create<CalendarState>()(
     const task = get().tasks.find((t) => t.id === id);
     if (!task) return;
     const completed = task.progress === 'completed';
-    // Un-completing goes back to needs-action (not in-process), like webmail;
-    // progressUpdated records when the state changed (RFC 8984 §5.2.4).
+    // Un-completing goes back to needs-action (not in-process), like webmail.
+    // No progressUpdated: JSCalendar 2.0 dropped it and Stalwart rejects the
+    // whole update with invalidProperties (#958).
     const next: Partial<CalendarEvent> = completed
-      ? { progress: 'needs-action', percentComplete: 0, progressUpdated: new Date().toISOString() }
-      : { progress: 'completed', percentComplete: 100, progressUpdated: new Date().toISOString() };
-    await get().updateTask(id, next);
+      ? { progress: 'needs-action', percentComplete: 0 }
+      : { progress: 'completed', percentComplete: 100 };
+    // Flip the checkbox right away and put it back if the server refuses.
+    const patchTask = (changes: Partial<CalendarEvent>) =>
+      set({ tasks: get().tasks.map((t) => (t.id === id ? { ...t, ...changes } : t)) });
+    patchTask(next);
+    try {
+      await apiUpdateEvent(task.originalId || id, next, undefined, task.accountId);
+    } catch (err) {
+      patchTask({ progress: task.progress, percentComplete: task.percentComplete });
+      throw err;
+    }
   },
 
   deleteTask: async (id) => {