add: 添加每月最后一天调度

webgui/api/server.py

@@ -38,6 +38,7 @@ ALLOWED_ORIGINS = {
 }
 VALID_ACTIONS = {"copy", "sync", "move"}
 VALID_SCHEDULE_KINDS = {"daily", "weekly", "monthly"}
+MONTHDAY_LAST = 0
 
 db_lock = threading.RLock()
 scheduler_lock = threading.RLock()
@@ -142,13 +143,15 @@ def compute_next_run_at(
         return iso(local_to_utc(candidate, offset_minutes))
 
     if kind == "monthly":
-        if monthday is None or monthday < 1 or monthday > 31:
-            raise ValueError("scheduleMonthday must be 1-31")
+        if monthday is None or monthday < MONTHDAY_LAST or monthday > 31:
+            raise ValueError("scheduleMonthday must be 0-31")
         for offset_months in range(0, 36):
             year, month = add_months(local_after.year, local_after.month, offset_months)
-            if monthday > monthrange(year, month)[1]:
+            days_in_month = monthrange(year, month)[1]
+            candidate_day = days_in_month if monthday == MONTHDAY_LAST else monthday
+            if candidate_day > days_in_month:
                 continue
-            candidate = datetime(year, month, monthday, hour, minute)
+            candidate = datetime(year, month, candidate_day, hour, minute)
             if candidate > local_after:
                 return iso(local_to_utc(candidate, offset_minutes))
         raise ValueError("could not compute next monthly run")

webgui/api/server_test.py

@@ -48,6 +48,20 @@ class ComputeNextRunAtTest(unittest.TestCase):
             "2026-03-31T23:00:00Z",
         )
 
+    def test_monthly_last_day_uses_current_month_end(self):
+        after = datetime(2026, 2, 1, 0, 0, tzinfo=timezone.utc)
+        self.assertEqual(
+            compute_next_run_at("monthly", "23:00", 0, after, monthday=0),
+            "2026-02-28T23:00:00Z",
+        )
+
+    def test_monthly_last_day_rolls_forward_when_current_month_end_passed(self):
+        after = datetime(2026, 2, 28, 23, 0, tzinfo=timezone.utc)
+        self.assertEqual(
+            compute_next_run_at("monthly", "23:00", 0, after, monthday=0),
+            "2026-03-31T23:00:00Z",
+        )
+
     def test_timezone_offset_is_applied_from_local_schedule_time(self):
         after = datetime(2026, 6, 20, 12, 0, tzinfo=timezone.utc)
         self.assertEqual(