Recompute the local calendar event instead of caching it

homeassistant/components/local_calendar/calendar.py

@@ -10,6 +10,7 @@
 from ical.event import Event
 from ical.exceptions import CalendarParseError
 from ical.store import EventStore, EventStoreError
+from ical.timeline import Timeline, materialize_timeline
 from ical.types import Range, Recur
 import voluptuous as vol
 
@@ -34,6 +35,12 @@
 
 PRODID = "-//homeassistant.io//local_calendar 1.0//EN"
 
+# Materialize a bounded timeline of upcoming events on every update so the
+# state can be recomputed synchronously, without walking recurrence rules in
+# the event loop. Mirrors what remote_calendar does.
+MAX_LOOKAHEAD_EVENTS = 20
+MAX_LOOKAHEAD_TIME = timedelta(days=365)
+
 
 async def async_setup_entry(
     hass: HomeAssistant,
@@ -74,15 +81,20 @@ def __init__(
         self._store = store
         self._calendar = calendar
         self._calendar_lock = asyncio.Lock()
-        self._event: CalendarEvent | None = None
+        self._timeline: Timeline | None = None
         self._attr_name = name
         self._attr_unique_id = unique_id
 
     @property
     @override
     def event(self) -> CalendarEvent | None:
         """Return the next upcoming event."""
-        return self._event
+        if self._timeline is None:
+            return None
+        events = self._timeline.active_after(dt_util.now())
+        if event := next(events, None):
+            return _get_calendar_event(event)
+        return None
 
     @override
     async def async_get_events(
@@ -102,14 +114,16 @@ def events_in_range() -> list[CalendarEvent]:
     async def async_update(self) -> None:
         """Update entity state with the next upcoming event."""
 
-        def next_event() -> CalendarEvent | None:
+        def _get_timeline() -> Timeline:
             now = dt_util.now()
-            events = self._calendar.timeline_tz(now.tzinfo).active_after(now)
-            if event := next(events, None):
-                return _get_calendar_event(event)
-            return None
+            return materialize_timeline(
+                self._calendar.timeline_tz(now.tzinfo),
+                start=now,
+                stop=now + MAX_LOOKAHEAD_TIME,
+                max_number_of_events=MAX_LOOKAHEAD_EVENTS,
+            )
 
-        self._event = await self.hass.async_add_executor_job(next_event)
+        self._timeline = await self.hass.async_add_executor_job(_get_timeline)
 
     async def _async_store(self) -> None:
         """Persist the calendar to disk."""

tests/components/local_calendar/test_calendar.py

@@ -1,13 +1,18 @@
 """Tests for calendar platform of local calendar."""
 
 import datetime
+from datetime import timedelta
 import textwrap
+from unittest.mock import patch
 
+from freezegun.api import FrozenDateTimeFactory
 import pytest
 
+from homeassistant.components.local_calendar.const import DOMAIN
 from homeassistant.const import STATE_OFF, STATE_ON
 from homeassistant.core import HomeAssistant
 from homeassistant.helpers.template import DATE_STR_FORMAT
+from homeassistant.setup import async_setup_component
 from homeassistant.util import dt as dt_util
 
 from .conftest import (
@@ -18,7 +23,7 @@
     event_fields,
 )
 
-from tests.common import MockConfigEntry
+from tests.common import MockConfigEntry, async_fire_time_changed
 
 
 async def test_empty_calendar(
@@ -1158,3 +1163,58 @@ async def test_invalid_event_duration(
             "end": {"dateTime": "1997-07-14T11:30:00-06:00"},
         }
     ]
+
+
+ADJACENT_EVENTS_ICS = """BEGIN:VCALENDAR
+PRODID:-//homeassistant.io//local_calendar 1.0//EN
+VERSION:2.0
+BEGIN:VEVENT
+DTSTART:20260729T014500
+DTEND:20260729T020000
+SUMMARY:First
+UID:first
+END:VEVENT
+BEGIN:VEVENT
+DTSTART:20260729T020000
+DTEND:20260729T021500
+SUMMARY:Second
+UID:second
+END:VEVENT
+END:VCALENDAR
+"""
+
+
+@pytest.mark.parametrize("ics_content", [ADJACENT_EVENTS_ICS])
+async def test_adjacent_events_stay_on(
+    hass: HomeAssistant,
+    freezer: FrozenDateTimeFactory,
+    config_entry: MockConfigEntry,
+) -> None:
+    """Test the state stays on when one event ends as the next one begins.
+
+    The scan interval is widened so the platform poll cannot reach the boundary
+    first: what is under test is the alarm scheduled for the end of the current
+    event, which has to be able to pick up the next one on its own.
+    """
+    freezer.move_to("2026-07-29 07:50:20+00:00")  # 01:50:20 in America/Regina
+
+    config_entry.add_to_hass(hass)
+    with patch("homeassistant.components.calendar.SCAN_INTERVAL", timedelta(hours=1)):
+        assert await async_setup_component(hass, DOMAIN, {})
+        await hass.async_block_till_done()
+
+        state = hass.states.get(TEST_ENTITY)
+        assert state.state == STATE_ON
+        assert state.attributes["message"] == "First"
+
+        for offset in (0, 1, 30, 59):
+            freezer.move_to(
+                datetime.datetime(2026, 7, 29, 8, 0, tzinfo=datetime.UTC)
+                + datetime.timedelta(seconds=offset)
+            )
+            async_fire_time_changed(hass, dt_util.utcnow())
+            await hass.async_block_till_done()
+
+            state = hass.states.get(TEST_ENTITY)
+            assert state.state == STATE_ON, f"off at 02:00:{offset:02d}"
+            assert state.attributes["message"] == "Second"