refactor: change backup_orders to use cutoff param instead of start/end

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/test_backup.py

@@ -41,8 +41,7 @@ def test_backup_filters_by_state_and_date(tmp_path):
     result = backup_orders(
         scan_path=scan_csv,
         backup_dir=backup_dir,
-        start=datetime(2025, 1, 1, tzinfo=timezone.utc),
-        end=datetime(2025, 1, 3, tzinfo=timezone.utc),
+        cutoff=datetime(2025, 1, 3, tzinfo=timezone.utc),
     )
 
     assert result == 2
@@ -56,3 +55,30 @@ def test_backup_filters_by_state_and_date(tmp_path):
     jan1_rows = list(read_csv(jan1))
     assert len(jan1_rows) == 1
     assert jan1_rows[0]["RowKey"] == "o1"
+
+
+def test_backup_filters_by_cutoff(tmp_path):
+    scan_dir = tmp_path / "scan"
+    backup_dir = tmp_path / "backups"
+    scan_dir.mkdir()
+    backup_dir.mkdir()
+
+    entities = [
+        _make_entity("u1", "o1", datetime(2025, 1, 1, 10, tzinfo=timezone.utc), 1),
+        _make_entity("u2", "o2", datetime(2025, 1, 2, 8, tzinfo=timezone.utc), 1),
+        _make_entity("u3", "o3", datetime(2025, 1, 3, 8, tzinfo=timezone.utc), 1),  # at/after cutoff
+    ]
+    scan_csv = scan_dir / "scan-2025-01-03.csv"
+    write_csv(scan_csv, entities)
+
+    cutoff = datetime(2025, 1, 3, tzinfo=timezone.utc)
+    result = backup_orders(
+        scan_path=scan_csv,
+        backup_dir=backup_dir,
+        cutoff=cutoff,
+    )
+
+    assert result == 2
+    assert (backup_dir / "2025-01-01.csv").exists()
+    assert (backup_dir / "2025-01-02.csv").exists()
+    assert not (backup_dir / "2025-01-03.csv").exists()