feat: sort tasks by due time

tests/test_mvp_backend.py

@@ -1,7 +1,12 @@
-from datetime import datetime, timedelta
+from datetime import UTC, datetime, timedelta
+from uuid import UUID
 from zoneinfo import ZoneInfo
 
-from sqlalchemy import event
+from sqlalchemy import event, select, text
+from sqlalchemy.dialects import postgresql
+from sqlalchemy.ext.asyncio import async_sessionmaker
+
+from backend.models import RecurrenceException, RecurrenceTemplate, Task, UTCDateTime
 
 BUSINESS_TIME_ZONE = ZoneInfo("Asia/Shanghai")
 
@@ -138,7 +143,7 @@ def test_completing_repeating_task_advances_due_date_instead_of_closing_it(clien
     assert completed.json()["completed"] is False
     assert completed.json()["due_at"].replace("Z", "") == "2026-09-08T09:00:00"
     recurrence = client.get(f"/api/v1/tasks/{task['id']}/recurrence").json()
-    assert recurrence["starts_at"].replace("Z", "") == "2026-09-08T09:00:00"
+    assert datetime.fromisoformat(recurrence["starts_at"]) == datetime(2026, 9, 8, 9, tzinfo=UTC)
 
 
 def test_completing_repeating_task_resets_completed_subtasks_for_next_occurrence(client):
@@ -207,6 +212,95 @@ def test_recurrence_mutations_keep_exact_timestamp_validation(client):
     assert same_instant.status_code == 200
 
 
+def test_recurrence_chain_normalizes_absolute_instants_to_utc_on_sqlite(client):
+    inbox = boot(client)
+    created = client.post(
+        "/api/v1/tasks",
+        json={
+            "title": "北京时间重复任务",
+            "list_id": inbox["id"],
+            "due_at": "2026-09-07T16:00:00+08:00",
+            "rrule": "FREQ=DAILY;COUNT=3",
+        },
+    )
+    assert created.status_code == 201
+    task = created.json()
+    assert datetime.fromisoformat(task["due_at"]) == datetime(2026, 9, 7, 8, tzinfo=UTC)
+
+    recurrence = client.get(f"/api/v1/tasks/{task['id']}/recurrence").json()
+    assert datetime.fromisoformat(recurrence["starts_at"]) == datetime(2026, 9, 7, 8, tzinfo=UTC)
+
+    edited = client.patch(
+        f"/api/v1/recurrences/{recurrence['id']}",
+        params={"scope": "this", "occurrence_at": "2026-09-08T16:00:00+08:00"},
+        json={"due_at": "2026-09-08T17:30:00+08:00"},
+    )
+    assert edited.status_code == 200
+    completed = client.post(
+        f"/api/v1/recurrences/{recurrence['id']}/complete",
+        json={"occurrence_at": "2026-09-08T16:00:00+08:00"},
+    )
+    assert completed.status_code == 200
+
+    async def stored_values():
+        from backend.db import get_engine
+
+        session_factory = async_sessionmaker(get_engine(), expire_on_commit=False)
+        async with session_factory() as db:
+            template = await db.scalar(
+                select(RecurrenceTemplate).where(RecurrenceTemplate.id == UUID(recurrence["id"]))
+            )
+            exception = await db.scalar(
+                select(RecurrenceException).where(RecurrenceException.template_id == template.id)
+            )
+            return template.starts_at, exception.occurrence_at, exception.due_at, exception.completed
+
+    import asyncio
+
+    starts_at, occurrence_at, due_at, is_completed = asyncio.run(stored_values())
+    assert starts_at == datetime(2026, 9, 7, 8, tzinfo=UTC)
+    assert occurrence_at == datetime(2026, 9, 8, 8, tzinfo=UTC)
+    assert due_at == datetime(2026, 9, 8, 9, 30, tzinfo=UTC)
+    assert is_completed is True
+
+
+def test_utc_datetime_reads_legacy_sqlite_offset_text_as_the_same_instant(client):
+    inbox = boot(client)
+    task = client.post(
+        "/api/v1/tasks",
+        json={"title": "历史数据", "list_id": inbox["id"], "due_at": "2026-09-07T08:00:00Z"},
+    ).json()
+
+    async def inject_and_read():
+        from backend.db import get_engine
+
+        engine = get_engine()
+        async with engine.begin() as connection:
+            await connection.execute(
+                text("UPDATE tasks SET due_at = :value WHERE id = :task_id"),
+                {"value": "2026-09-07 16:00:00+08:00", "task_id": task["id"]},
+            )
+        session_factory = async_sessionmaker(engine, expire_on_commit=False)
+        async with session_factory() as db:
+            return await db.scalar(select(Task.due_at).where(Task.id == UUID(task["id"])))
+
+    import asyncio
+
+    assert asyncio.run(inject_and_read()) == datetime(2026, 9, 7, 8, tzinfo=UTC)
+
+
+def test_recurrence_absolute_columns_use_utc_type_without_schema_change():
+    for column in (
+        Task.__table__.c.due_at,
+        RecurrenceTemplate.__table__.c.starts_at,
+        RecurrenceTemplate.__table__.c.ends_at,
+        RecurrenceException.__table__.c.occurrence_at,
+        RecurrenceException.__table__.c.due_at,
+    ):
+        assert isinstance(column.type, UTCDateTime)
+        assert column.type.compile(dialect=postgresql.dialect()) == "TIMESTAMP WITH TIME ZONE"
+
+
 def test_recurrence_rejects_occurrence_after_cutoff(client):
     inbox = boot(client)
     task = client.post(
@@ -412,7 +506,8 @@ def test_tasks_support_numbered_pagination_with_total(client):
 
 def test_tasks_support_due_range_pagination(client):
     inbox = boot(client)
-    client.post("/api/v1/tasks", json={"title": "今天", "list_id": inbox["id"], "due_at": "2026-09-05T08:00:00Z"})
+    client.post("/api/v1/tasks", json={"title": "今天较晚", "list_id": inbox["id"], "due_at": "2026-09-05T18:00:00Z"})
+    client.post("/api/v1/tasks", json={"title": "今天较早", "list_id": inbox["id"], "due_at": "2026-09-05T08:00:00Z"})
     client.post("/api/v1/tasks", json={"title": "以后", "list_id": inbox["id"], "due_at": "2026-09-08T08:00:00Z"})
     client.post("/api/v1/tasks", json={"title": "无日期", "list_id": inbox["id"]})
 
@@ -422,8 +517,8 @@ def test_tasks_support_due_range_pagination(client):
     )
 
     assert response.status_code == 200
-    assert response.json()["total"] == 1
-    assert [item["title"] for item in response.json()["items"]] == ["今天"]
+    assert response.json()["total"] == 2
+    assert [item["title"] for item in response.json()["items"]] == ["今天较早", "今天较晚"]
 
 
 def test_trash_supports_numbered_pagination_with_total(client):