feat: auto-refresh calendar subscriptions

backend/calendar_refresh.py

@@ -0,0 +1,108 @@
+from __future__ import annotations
+
+import asyncio
+import logging
+from collections.abc import Callable
+from datetime import UTC, datetime, timedelta
+
+from fastapi import HTTPException
+from sqlalchemy import or_, select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from . import calendar as calendar_service
+from .models import CalendarSubscription, utcnow
+
+logger = logging.getLogger(__name__)
+DEFAULT_REFRESH_INTERVAL = timedelta(minutes=15)
+DEFAULT_POLL_SECONDS = 60
+
+
+async def refresh_subscription_cache(
+    db: AsyncSession,
+    row: CalendarSubscription,
+    *,
+    fail_without_cache: bool = True,
+) -> bool:
+    requested_url = row.url
+    requested_version = getattr(row, "updated_at", None)
+    try:
+        result = await asyncio.to_thread(
+            calendar_service.fetch_calendar,
+            requested_url,
+            etag=row.etag,
+            last_modified=row.last_modified,
+        )
+        await db.refresh(row)
+        if row.url != requested_url or getattr(row, "updated_at", None) != requested_version:
+            return False
+        if result.not_modified:
+            if not row.ics_cache:
+                raise HTTPException(502, "calendar returned not modified without cache")
+        elif result.content is not None:
+            # Parse before replacing a known-good cache.
+            calendar_service.parse_ics_events(
+                result.content,
+                row.name,
+                row.color,
+                datetime.now(UTC) - timedelta(days=1),
+                datetime.now(UTC) + timedelta(days=1),
+                "UTC",
+            )
+            row.ics_cache = result.content.decode("utf-8-sig")
+            row.etag = result.etag
+            row.last_modified = result.last_modified
+        row.refreshed_at = utcnow()
+        row.last_error = None
+        await db.commit()
+        return True
+    except Exception as exc:
+        error = exc.detail if isinstance(exc, HTTPException) else str(exc)
+        if not row.ics_cache and fail_without_cache:
+            await db.rollback()
+            raise HTTPException(502, error) from exc
+        row.last_error = error
+        await db.commit()
+        return False
+
+
+async def refresh_due_subscriptions(
+    db: AsyncSession,
+    *,
+    now: datetime | None = None,
+    refresh_interval: timedelta = DEFAULT_REFRESH_INTERVAL,
+) -> int:
+    current = now or datetime.now(UTC)
+    cutoff = current - refresh_interval
+    rows = (await db.scalars(select(CalendarSubscription).where(
+        CalendarSubscription.enabled.is_(True),
+        or_(
+            CalendarSubscription.refreshed_at.is_(None),
+            CalendarSubscription.refreshed_at <= cutoff,
+        ),
+    ).order_by(CalendarSubscription.refreshed_at, CalendarSubscription.created_at))).all()
+    for row in rows:
+        try:
+            await refresh_subscription_cache(db, row, fail_without_cache=False)
+        except Exception:
+            await db.rollback()
+            logger.exception("Unexpected calendar refresh failure", extra={"subscription_id": str(row.id)})
+    return len(rows)
+
+
+async def calendar_refresh_loop(
+    session_factory: Callable[[], AsyncSession],
+    stop_event: asyncio.Event,
+    *,
+    refresh_interval: timedelta = DEFAULT_REFRESH_INTERVAL,
+    poll_seconds: int = DEFAULT_POLL_SECONDS,
+) -> None:
+    while not stop_event.is_set():
+        try:
+            async with session_factory() as db:
+                await refresh_due_subscriptions(db, refresh_interval=refresh_interval)
+        except Exception:
+            logger.exception("Calendar background refresh cycle failed")
+        try:
+            await asyncio.wait_for(stop_event.wait(), timeout=poll_seconds)
+        except TimeoutError:
+            pass

backend/calendar_router.py

@@ -1,4 +1,4 @@
-from datetime import UTC, datetime, timedelta
+from datetime import datetime, timedelta
 from uuid import UUID
 from zoneinfo import ZoneInfo, ZoneInfoNotFoundError
 
@@ -9,8 +9,9 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from . import calendar as calendar_service
 from .auth import current_user
+from .calendar_refresh import refresh_subscription_cache
 from .db import get_db
-from .models import CalendarSubscription, User, utcnow
+from .models import CalendarSubscription, User
 
 router = APIRouter(prefix="/api/v1", tags=["calendar"])
 MAX_WINDOW = timedelta(days=366)
@@ -90,37 +91,6 @@ async def _owned(db: AsyncSession, user_id: UUID, subscription_id: UUID) -> Cale
     return row
 
 
-async def _refresh(db: AsyncSession, row: CalendarSubscription) -> None:
-    try:
-        result = await __import__("asyncio").to_thread(
-            calendar_service.fetch_calendar, row.url, etag=row.etag, last_modified=row.last_modified
-        )
-        if result.not_modified:
-            if not row.ics_cache:
-                raise HTTPException(502, "calendar returned not modified without cache")
-        elif result.content is not None:
-            # Parse before replacing a known-good cache.
-            calendar_service.parse_ics_events(
-                result.content,
-                row.name,
-                row.color,
-                datetime.now(UTC) - timedelta(days=1),
-                datetime.now(UTC) + timedelta(days=1),
-                "UTC",
-            )
-            row.ics_cache = result.content.decode("utf-8-sig")
-            row.etag = result.etag
-            row.last_modified = result.last_modified
-        row.refreshed_at = utcnow()
-        row.last_error = None
-    except Exception as exc:
-        row.last_error = exc.detail if isinstance(exc, HTTPException) else str(exc)
-        if not row.ics_cache:
-            await db.rollback()
-            raise HTTPException(502, row.last_error) from exc
-    await db.commit()
-
-
 @router.get("/calendar-subscriptions", response_model=list[SubscriptionOut])
 async def list_subscriptions(user: User = Depends(current_user), db: AsyncSession = Depends(get_db)):
     rows = (await db.scalars(select(CalendarSubscription).where(
@@ -139,7 +109,7 @@ async def create_subscription(
     row = CalendarSubscription(user_id=user.id, **payload.model_dump())
     db.add(row)
     await db.flush()
-    await _refresh(db, row)
+    await refresh_subscription_cache(db, row)
     await db.refresh(row)
     return _out(row)
 
@@ -183,7 +153,7 @@ async def refresh_subscription(
     db: AsyncSession = Depends(get_db),
 ):
     row = await _owned(db, user.id, subscription_id)
-    await _refresh(db, row)
+    await refresh_subscription_cache(db, row)
     await db.refresh(row)
     return _out(row)
 
@@ -209,7 +179,7 @@ async def calendar_events(
     sources = []
     for row in rows:
         if not row.ics_cache:
-            await _refresh(db, row)
+            await refresh_subscription_cache(db, row)
         try:
             parsed = calendar_service.parse_ics_events(
                 row.ics_cache or "", row.name, row.color, start, end, user.timezone,

backend/db.py

@@ -22,6 +22,12 @@ def get_engine():
     return _engine
 
 
+def get_session_factory() -> async_sessionmaker[AsyncSession]:
+    get_engine()
+    assert _session_factory is not None
+    return _session_factory
+
+
 def reset_engine() -> None:
     global _engine, _session_factory
     _engine = None
@@ -29,9 +35,7 @@ def reset_engine() -> None:
 
 
 async def get_db() -> AsyncIterator[AsyncSession]:
-    get_engine()
-    assert _session_factory is not None
-    async with _session_factory() as session:
+    async with get_session_factory()() as session:
         yield session
 
 

backend/main.py

@@ -1,3 +1,4 @@
+import asyncio
 import base64
 import json
 import logging
@@ -30,8 +31,9 @@ from .auth import (
     verify_password,
 )
 from .backup import router as backup_router
+from .calendar_refresh import calendar_refresh_loop
 from .calendar_router import router as calendar_router
-from .db import create_schema, get_db
+from .db import create_schema, get_db, get_session_factory
 from .models import (
     AppState,
     Attachment,
@@ -80,7 +82,19 @@ async def lifespan(app: FastAPI):
 
     if get_settings().auto_create_schema:
         await create_schema()
+    stop_calendar_refresh = asyncio.Event()
+    calendar_refresh_task = asyncio.create_task(
+        calendar_refresh_loop(get_session_factory(), stop_calendar_refresh)
+    )
+    try:
         yield
+    finally:
+        stop_calendar_refresh.set()
+        calendar_refresh_task.cancel()
+        try:
+            await calendar_refresh_task
+        except asyncio.CancelledError:
+            pass
 
 
 app = FastAPI(

frontend/src/CalendarPanel.test.ts

@@ -92,6 +92,7 @@ describe('CalendarPanel',()=>{
   vi.useRealTimers()
  })
  it('keeps the newest week response when requests finish out of order',async()=>{
+  vi.useFakeTimers();vi.setSystemTime(new Date(2026,8,20,10))
   const pending:Array<{url:string;resolve:(response:Response)=>void}>=[]
   const fetchMock=vi.fn((url:string)=>String(url).includes('calendar-events')?new Promise<Response>(resolve=>pending.push({url:String(url),resolve})):Promise.resolve(json(subscriptions)))
   const {host}=await mount(fetchMock)
@@ -102,6 +103,7 @@ describe('CalendarPanel',()=>{
   pending[0].resolve(json({events:[{...events[0],id:'old',title:'旧一周'}],sources:[]}));await flush()
   expect(host.textContent).toContain('新一周')
   expect(host.textContent).not.toContain('旧一周')
+  vi.useRealTimers()
  })
  it('supports week navigation and today',async()=>{
   const fetchMock=vi.fn((url:string)=>Promise.resolve(json(url.includes('calendar-events')?{events:[],sources:[]}:subscriptions)))

tests/test_calendar_subscriptions.py

@@ -1,5 +1,7 @@
+import asyncio
 import socket
-from datetime import UTC, datetime
+from datetime import UTC, datetime, timedelta
+from types import SimpleNamespace
 
 import pytest
 from fastapi import HTTPException
@@ -9,6 +11,7 @@ from backend.calendar import (
     parse_ics_events,
     validate_calendar_url,
 )
+from backend.calendar_refresh import refresh_due_subscriptions, refresh_subscription_cache
 
 ICS = b"""BEGIN:VCALENDAR\r
 VERSION:2.0\r
@@ -234,3 +237,117 @@ def test_subscription_ownership_is_strict(client, monkeypatch):
     client.post("/api/v1/auth/logout")
     assert client.patch(f"/api/v1/calendar-subscriptions/{sub['id']}", json={"name": "x"}).status_code == 401
     assert client.delete(f"/api/v1/calendar-subscriptions/{sub['id']}").status_code == 401
+
+
+def test_due_enabled_subscriptions_refresh_automatically(client, monkeypatch):
+    client = initialized(client)
+    monkeypatch.setattr(
+        "backend.calendar.validate_calendar_url",
+        lambda url: (url, "93.184.216.34", 443),
+    )
+    calls = []
+
+    def fetch(url, *, etag=None, last_modified=None):
+        calls.append(url)
+        return FetchResult(ICS, None, None, False)
+
+    monkeypatch.setattr("backend.calendar.fetch_calendar", fetch)
+    client.post(
+        "/api/v1/calendar-subscriptions",
+        json={"name": "enabled", "url": "https://example.com/enabled.ics"},
+    )
+    client.post(
+        "/api/v1/calendar-subscriptions",
+        json={"name": "disabled", "url": "https://example.com/disabled.ics", "enabled": False},
+    )
+
+    async def refresh():
+        from sqlalchemy.ext.asyncio import async_sessionmaker
+
+        from backend.db import get_engine
+
+        factory = async_sessionmaker(get_engine(), expire_on_commit=False)
+        async with factory() as db:
+            return await refresh_due_subscriptions(
+                db,
+                now=datetime.now(UTC) + timedelta(minutes=16),
+                refresh_interval=timedelta(minutes=15),
+            )
+
+    assert asyncio.run(refresh()) == 1
+    assert calls == [
+        "https://example.com/enabled.ics",
+        "https://example.com/disabled.ics",
+        "https://example.com/enabled.ics",
+    ]
+
+
+def test_failed_cached_refresh_preserves_last_success_timestamp(monkeypatch):
+    original_refresh = datetime(2026, 9, 20, tzinfo=UTC)
+    row = SimpleNamespace(
+        id="source-1",
+        url="https://example.com/work.ics",
+        name="work",
+        color="#123456",
+        ics_cache=ICS.decode(),
+        etag=None,
+        last_modified=None,
+        refreshed_at=original_refresh,
+        last_error=None,
+    )
+
+    class FakeDb:
+        async def refresh(self, _row):
+            pass
+
+        async def commit(self):
+            pass
+
+        async def rollback(self):
+            pass
+
+    def fail(*args, **kwargs):
+        raise HTTPException(502, "upstream down")
+
+    monkeypatch.setattr("backend.calendar.fetch_calendar", fail)
+    assert asyncio.run(refresh_subscription_cache(FakeDb(), row)) is False
+    assert row.refreshed_at == original_refresh
+    assert row.last_error == "upstream down"
+
+
+def test_refresh_discards_response_when_url_changes_in_flight(monkeypatch):
+    row = SimpleNamespace(
+        id="source-1",
+        url="https://example.com/old.ics",
+        name="work",
+        color="#123456",
+        ics_cache="old cache",
+        etag=None,
+        last_modified=None,
+        refreshed_at=datetime(2026, 9, 20, tzinfo=UTC),
+        last_error=None,
+    )
+
+    class FakeDb:
+        committed = False
+
+        async def refresh(self, target):
+            target.url = "https://example.com/new.ics"
+            target.ics_cache = None
+            target.refreshed_at = None
+
+        async def commit(self):
+            self.committed = True
+
+        async def rollback(self):
+            pass
+
+    monkeypatch.setattr(
+        "backend.calendar.fetch_calendar",
+        lambda *args, **kwargs: FetchResult(ICS, None, None, False),
+    )
+    db = FakeDb()
+    assert asyncio.run(refresh_subscription_cache(db, row)) is False
+    assert row.url == "https://example.com/new.ics"
+    assert row.ics_cache is None
+    assert db.committed is False