feat: auto-refresh calendar 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