feat: apply node timezone before scheduled jobs

Read an optional configs/timezone declaration and refresh active cron after a timezone change. Report a failed cron restart instead of claiming success.

Disclosure: I'm an AI assistant helping Vladimir Eremin; I'm not Vladimir Eremin.

tests/test_timezone.py

@@ -0,0 +1,72 @@
+import importlib.util
+from pathlib import Path
+import tempfile
+from types import SimpleNamespace
+import unittest
+from unittest.mock import Mock
+
+ROOT = Path(__file__).resolve().parents[1]
+spec = importlib.util.spec_from_file_location('timezone_action', ROOT / 'actions/configure/timezone.py')
+action = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(action)
+
+
+class TestTimezone(unittest.TestCase):
+    def setUp(self):
+        self.tmp = tempfile.TemporaryDirectory()
+        self.addCleanup(self.tmp.cleanup)
+        self.source = Path(self.tmp.name) / 'timezone'
+        self.zone = 'UTC'
+        self.cron_refreshes = []
+        def read(*args, **kwargs):
+            return SimpleNamespace(stdout=self.zone+'\n')
+        def apply(args):
+            self.zone = args[-1]
+        self.system = Mock()
+        self.system.run.side_effect = read
+        self.system.sudo.side_effect = apply
+        self.system.service_is_active.return_value = True
+        def restart(name):
+            self.cron_refreshes.append(name)
+            return True
+        self.system.restart.side_effect = restart
+        self.ctx = SimpleNamespace(paths=SimpleNamespace(configs=self.tmp.name), sys=self.system, log=Mock())
+
+    def test_timezone_transition_refreshes_cron_once_and_repeat_is_noop(self):
+        self.source.write_text('Europe/Moscow\n')
+        action.run(self.ctx, SimpleNamespace(dry_run=False))
+        self.assertEqual(self.zone, 'Europe/Moscow')
+        self.assertEqual(self.cron_refreshes, ['cron'])
+        action.run(self.ctx, SimpleNamespace(dry_run=False))
+        self.assertEqual(self.cron_refreshes, ['cron'])
+
+    def test_preview_and_absent_config_preserve_host(self):
+        action.run(self.ctx, SimpleNamespace(dry_run=False))
+        self.source.write_text('Europe/Moscow\n')
+        action.run(self.ctx, SimpleNamespace(dry_run=True))
+        self.assertEqual(self.zone, 'UTC')
+        self.assertEqual(self.cron_refreshes, [])
+        self.system.sudo.assert_not_called()
+
+    def test_failed_cron_restart_is_reported_as_failure(self):
+        self.source.write_text('Europe/Moscow\n')
+        self.system.restart.side_effect = None
+        self.system.restart.return_value = False
+        with self.assertRaises(SystemExit):
+            action.run(self.ctx, SimpleNamespace(dry_run=False))
+        self.ctx.log.success.assert_not_called()
+        self.assertEqual(self.zone, 'Europe/Moscow')
+
+    def test_inactive_cron_is_not_started(self):
+        self.source.write_text('Europe/Moscow\n')
+        self.system.service_is_active.return_value = False
+        action.run(self.ctx, SimpleNamespace(dry_run=False))
+        self.assertEqual(self.zone, 'Europe/Moscow')
+        self.assertEqual(self.cron_refreshes, [])
+
+    def test_invalid_zone_does_not_mutate_host(self):
+        self.source.write_text('../not-a-zone\n')
+        with self.assertRaises(SystemExit):
+            action.run(self.ctx, SimpleNamespace(dry_run=False))
+        self.system.sudo.assert_not_called()
+        self.assertEqual(self.cron_refreshes, [])