Pass the configured timezone to zigpy for Time cluster DST support

tests/test_climate.py

@@ -391,7 +391,8 @@ async def test_sinope_time(
 
     write_attributes.reset_mock()
 
-    # Default time zone of UTC
+    # No configured timezone (local_timezone is None): falls back to UTC.
+    assert zha_gateway.config.local_timezone is None
     with freeze_time("2000-01-02 00:00:00"):
         await entity._async_update_time()
         secs_since_2k = write_attributes.mock_calls[0].args[0]["secs_since_2k"]
@@ -400,7 +401,7 @@ async def test_sinope_time(
     write_attributes.reset_mock()
 
     # New time zone
-    zha_gateway.config.local_timezone = zoneinfo.ZoneInfo("America/New_York")
+    zha_gateway.update_local_timezone(zoneinfo.ZoneInfo("America/New_York"))
 
     with freeze_time("2000-01-02 00:00:00"):
         await entity._async_update_time()

tests/test_gateway.py

@@ -2,7 +2,9 @@
 
 import asyncio
 from contextlib import suppress
+from typing import Any
 from unittest.mock import AsyncMock, MagicMock, PropertyMock, call, patch
+import zoneinfo
 
 import pytest
 from zhaquirks.builder import QuirkBuilder
@@ -764,6 +766,96 @@ async def mock_send_packet(*args, **kwargs):  # pylint: disable=unused-argument
         assert 1 == max(concurrencies) == zha_gw.radio_concurrency
 
 
+@pytest.mark.parametrize(
+    "tz",
+    [
+        None,
+        zoneinfo.ZoneInfo("America/New_York"),
+    ],
+)
+async def test_configured_timezone_passed_to_controller(
+    tz: zoneinfo.ZoneInfo | None,
+    zigpy_app_controller: ControllerApplication,
+    zha_data: ZHAData,
+) -> None:
+    """Test that the configured timezone is forwarded to ControllerApplication.new."""
+    zha_data.local_timezone = tz
+    zha_gw = Gateway(zha_data)
+
+    with patch(
+        "bellows.zigbee.application.ControllerApplication.new",
+        AsyncMock(return_value=zigpy_app_controller),
+    ) as mock_new:
+        await zha_gw.async_initialize()
+
+    assert mock_new.call_args.kwargs["local_timezone"] == tz
+
+    await zha_gw.shutdown()
+
+
+async def test_update_local_timezone_syncs_controller(
+    zha_gateway: Gateway,
+) -> None:
+    """Test that update_local_timezone keeps ZHAData and the controller in sync."""
+    new_tz = zoneinfo.ZoneInfo("Europe/London")
+
+    zha_gateway.update_local_timezone(new_tz)
+
+    assert zha_gateway.config.local_timezone is new_tz
+    assert zha_gateway.application_controller.local_timezone is new_tz
+
+    # Also verify clearing to None propagates.
+    zha_gateway.update_local_timezone(None)
+
+    assert zha_gateway.config.local_timezone is None
+    assert zha_gateway.application_controller.local_timezone is None
+
+
+async def test_update_local_timezone_before_init(
+    zha_data: ZHAData,
+) -> None:
+    """Test update_local_timezone before and after controller lifecycle."""
+    tz = zoneinfo.ZoneInfo("America/Chicago")
+    gw = Gateway(zha_data)
+
+    # Before async_initialize: controller is None; must not raise.
+    gw.update_local_timezone(tz)
+    assert gw.config.local_timezone is tz
+    assert gw.application_controller is None
+
+    # After shutdown: controller is reset to None; must not raise.
+    await gw.shutdown()
+    gw.update_local_timezone(zoneinfo.ZoneInfo("Europe/Paris"))
+    assert gw.config.local_timezone == zoneinfo.ZoneInfo("Europe/Paris")
+    assert gw.application_controller is None
+
+
+async def test_update_local_timezone_during_controller_creation(
+    zigpy_app_controller: ControllerApplication,
+    zha_data: ZHAData,
+) -> None:
+    """Test a timezone update while ControllerApplication.new() is suspended."""
+    new_tz = zoneinfo.ZoneInfo("Europe/London")
+    zha_data.local_timezone = None
+    zha_gw = Gateway(zha_data)
+
+    async def slow_new(*args: Any, **kwargs: Any) -> ControllerApplication:
+        # Simulates the awaited database load: the update lands mid-creation.
+        zha_gw.update_local_timezone(new_tz)
+        zigpy_app_controller.local_timezone = kwargs["local_timezone"]
+        return zigpy_app_controller
+
+    with patch(
+        "bellows.zigbee.application.ControllerApplication.new",
+        AsyncMock(side_effect=slow_new),
+    ):
+        await zha_gw.async_initialize()
+
+    assert zha_gw.application_controller.local_timezone is new_tz
+
+    await zha_gw.shutdown()
+
+
 async def test_gateway_device_removed(zha_gateway: Gateway) -> None:
     """Test ZHA device removal."""
 

zha/application/gateway.py

@@ -6,7 +6,7 @@
 from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager, suppress
 from dataclasses import dataclass
-from datetime import timedelta
+from datetime import timedelta, tzinfo
 from enum import Enum
 import logging
 import random
@@ -262,6 +262,9 @@ async def _async_initialize(self) -> None:
         self.shutting_down = False
 
         app_controller_cls, app_config = self.get_application_controller_data()
+        # local_timezone is captured once at controller creation time.  For runtime
+        # changes (e.g. the host's timezone setting changes) call update_local_timezone()
+        # so that both ZHAData and the ControllerApplication stay in sync.
         self.application_controller = await app_controller_cls.new(
             config=app_config,
             auto_form=False,
@@ -270,7 +273,11 @@ async def _async_initialize(self) -> None:
             uninitialized_packet_handler=(
                 self.config.config.quirks_configuration.uninitialized_packet_handler
             ),
+            local_timezone=self.config.local_timezone,
         )
+        # `new()` awaits (database load), so `update_local_timezone()` may have run
+        # while `application_controller` was still None: re-apply the current value.
+        self.application_controller.local_timezone = self.config.local_timezone
 
         await self.application_controller.startup(auto_form=True)
 
@@ -294,6 +301,12 @@ async def async_initialize(self) -> None:
             await self.shutdown()
             raise
 
+    def update_local_timezone(self, tz: tzinfo | None) -> None:
+        """Update the local timezone used for ZCL Time cluster attributes."""
+        self.config.local_timezone = tz
+        if self.application_controller is not None:
+            self.application_controller.local_timezone = tz
+
     @asynccontextmanager
     async def request_priority(
         self, priority: t.PacketPriority | None

zha/application/helpers.py

@@ -428,7 +428,8 @@ class ZHAData:
         default_factory=dict
     )
     allow_polling: bool = dataclasses.field(default=False)
-    local_timezone: dt.tzinfo = dataclasses.field(default=dt.UTC)
+    # Set once at startup; use Gateway.update_local_timezone() for runtime changes.
+    local_timezone: dt.tzinfo | None = None
     country_code: str | None = None
 
 

zha/application/platforms/climate/__init__.py

@@ -1016,7 +1016,10 @@ def _rm_rs_action(self) -> HVACAction:
     async def _async_update_time(self) -> None:
         """Update thermostat's time display."""
 
-        now = dt.datetime.now(self._device.gateway.config.local_timezone)
+        # Fall back to UTC when no timezone is configured; datetime.now(None) would
+        # return a naive system-local datetime and produce wrong secs_since_2k values.
+        tz = self._device.gateway.config.local_timezone or dt.UTC
+        now = dt.datetime.now(tz)
         secs_2k = (
             now.replace(tzinfo=None) - dt.datetime(2000, 1, 1, 0, 0, 0, 0)
         ).total_seconds()