refactor: 重构 schemas 结构，统一枚举定义

backend/tests/unit/v1/schedule_items/test_service.py

@@ -500,3 +500,43 @@ async def test_list_by_date_range_rolls_back_when_query_fails_after_archive(
     assert exc_info.value.status_code == 503
     mock_session.rollback.assert_awaited_once()
     mock_session.commit.assert_not_awaited()
+
+
+@pytest.mark.asyncio
+async def test_get_by_id_maps_legacy_completed_to_archived(
+    mock_session: AsyncMock,
+    mock_inbox_repository: MagicMock,
+) -> None:
+    user_id = UUID("00000000-0000-0000-0000-000000000001")
+    item = _create_mock_schedule_item()
+    setattr(item, "status", "completed")
+    service = ScheduleItemService(
+        repository=FakeRepo(item),
+        session=mock_session,
+        current_user=CurrentUser(id=user_id),
+        inbox_repository=mock_inbox_repository,
+    )
+
+    result = await service.get_by_id(item.id)
+
+    assert result.status == ScheduleItemStatus.ARCHIVED
+
+
+@pytest.mark.asyncio
+async def test_get_by_id_maps_legacy_canceled_to_archived(
+    mock_session: AsyncMock,
+    mock_inbox_repository: MagicMock,
+) -> None:
+    user_id = UUID("00000000-0000-0000-0000-000000000001")
+    item = _create_mock_schedule_item()
+    setattr(item, "status", "canceled")
+    service = ScheduleItemService(
+        repository=FakeRepo(item),
+        session=mock_session,
+        current_user=CurrentUser(id=user_id),
+        inbox_repository=mock_inbox_repository,
+    )
+
+    result = await service.get_by_id(item.id)
+
+    assert result.status == ScheduleItemStatus.ARCHIVED