feat: align tariff resets to calendar month

tests/test_date_utils.py

@@ -0,0 +1,20 @@
+import unittest
+from datetime import datetime, timezone
+
+from bot.utils.date_utils import month_start
+
+
+class DateUtilsTests(unittest.TestCase):
+    def test_month_start_normalizes_aware_datetime(self):
+        dt = datetime(2026, 4, 28, 15, 45, tzinfo=timezone.utc)
+
+        result = month_start(dt)
+
+        self.assertEqual(result, datetime(2026, 4, 1, 0, 0, tzinfo=timezone.utc))
+
+    def test_month_start_normalizes_naive_datetime_as_utc(self):
+        dt = datetime(2026, 12, 31, 23, 59)
+
+        result = month_start(dt)
+
+        self.assertEqual(result, datetime(2026, 12, 1, 0, 0, tzinfo=timezone.utc))

tests/test_tariff_worker.py

@@ -0,0 +1,62 @@
+import unittest
+from datetime import datetime, timedelta, timezone
+from types import SimpleNamespace
+from unittest.mock import AsyncMock, patch
+
+from config.settings import Settings
+from bot.services.tariff_worker import TariffTrafficWorker
+from bot.utils.date_utils import month_start
+
+
+class TariffWorkerTests(unittest.IsolatedAsyncioTestCase):
+    async def test_monthly_reset_triggers_on_calendar_change_before_30_days(self):
+        settings = Settings(
+            _env_file=None,
+            BOT_TOKEN="token",
+            POSTGRES_USER="app_user",
+            POSTGRES_PASSWORD="app_password",
+        )
+        panel_service = AsyncMock()
+        panel_service.reset_user_traffic = AsyncMock(return_value=True)
+        panel_service.add_users_to_internal_squad = AsyncMock(return_value=True)
+        subscription_service = SimpleNamespace()
+        worker = TariffTrafficWorker(
+            settings=settings,
+            session_factory=SimpleNamespace(),
+            panel_service=panel_service,
+            subscription_service=subscription_service,
+        )
+
+        now = datetime.now(timezone.utc)
+        current_month_start = month_start(now)
+        previous_month_anchor = current_month_start - timedelta(days=2)
+        sub = SimpleNamespace(
+            subscription_id=1,
+            panel_user_uuid="panel-uuid",
+            period_start_at=previous_month_anchor,
+            end_date=now + timedelta(days=10),
+            traffic_used_bytes=123,
+            traffic_limit_bytes=456,
+            topup_balance_bytes=0,
+            is_throttled=False,
+            status_from_panel="ACTIVE",
+        )
+        tariff = SimpleNamespace(billing_model="period", squad_uuids=["squad-1"])
+
+        session = object()
+
+        with patch(
+            "bot.services.tariff_worker.subscription_dal.update_subscription",
+            new=AsyncMock(),
+        ) as update_subscription, patch(
+            "bot.services.tariff_worker.tariff_dal.clear_period_warnings",
+            new=AsyncMock(),
+        ) as clear_period_warnings:
+            await worker._maybe_reset_period(session, sub, tariff, used=123)
+
+        panel_service.reset_user_traffic.assert_awaited_once_with("panel-uuid")
+        update_subscription.assert_awaited_once()
+        update_payload = update_subscription.await_args.args[2]
+        self.assertEqual(update_payload["period_start_at"], current_month_start)
+        self.assertEqual(update_payload["traffic_used_bytes"], 0)
+        clear_period_warnings.assert_awaited_once_with(session, 1)