Fix test helper hour=23 bug and add row-count batching test

- Use timedelta(hours=1) instead of replace(hour=hour+1) in _window()
  to avoid ValueError when hour=23
- Add test_should_batch_by_row_count covering the >10K rows batching
  path (previously only the 2 MB size-limit path was tested)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_litellm/integrations/focus/test_vantage_destination.py

@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from datetime import datetime, timezone
+from datetime import datetime, timedelta, timezone
 from typing import Any, Dict, List
 from unittest.mock import AsyncMock, patch
 
@@ -12,12 +12,13 @@ from litellm.integrations.focus.destinations.base import FocusTimeWindow
 from litellm.integrations.focus.destinations.vantage_destination import (
     FocusVantageDestination,
     VANTAGE_MAX_BYTES_PER_UPLOAD,
+    VANTAGE_MAX_ROWS_PER_UPLOAD,
 )
 
 
 def _window(freq: str = "hourly", hour: int = 5) -> FocusTimeWindow:
     start = datetime(2024, 1, 2, hour, tzinfo=timezone.utc)
-    end = start.replace(hour=hour + 1)
+    end = start + timedelta(hours=1)
     return FocusTimeWindow(start_time=start, end_time=end, frequency=freq)
 
 
@@ -136,3 +137,51 @@ async def test_should_batch_large_content():
     # Each upload should be within limits
     for chunk in upload_calls:
         assert len(chunk) <= VANTAGE_MAX_BYTES_PER_UPLOAD
+
+
+@pytest.mark.asyncio
+async def test_should_batch_by_row_count():
+    """Verify batching triggers when row count exceeds 10K even if under 2 MB."""
+    dest = FocusVantageDestination(prefix="exports", config=_config())
+
+    header = b"col1"
+    # Short rows so total size stays well under 2 MB
+    row = b"x"
+    num_rows = VANTAGE_MAX_ROWS_PER_UPLOAD + 500
+    content = header + b"\n" + b"\n".join([row] * num_rows) + b"\n"
+
+    # Confirm content is under 2 MB but over 10K rows
+    assert len(content) < VANTAGE_MAX_BYTES_PER_UPLOAD
+    assert num_rows > VANTAGE_MAX_ROWS_PER_UPLOAD
+
+    upload_calls: List[bytes] = []
+
+    mock_response = AsyncMock()
+    mock_response.raise_for_status = lambda: None
+
+    mock_client = AsyncMock()
+    mock_client.__aenter__ = AsyncMock(return_value=mock_client)
+    mock_client.__aexit__ = AsyncMock(return_value=False)
+
+    async def capture_post(url, **kwargs):
+        files = kwargs.get("files", {})
+        if "file" in files:
+            upload_calls.append(files["file"][1])
+        return mock_response
+
+    mock_client.post = capture_post
+
+    with patch("litellm.integrations.focus.destinations.vantage_destination.httpx.AsyncClient", return_value=mock_client):
+        await dest.deliver(
+            content=content,
+            time_window=_window(),
+            filename="usage.csv",
+        )
+
+    # Should have made at least 2 uploads due to row count
+    assert len(upload_calls) >= 2
+    # Each batch should have at most 10K data rows (header + data rows + trailing newline)
+    for chunk in upload_calls:
+        lines = chunk.split(b"\n")
+        data_lines = [line for line in lines[1:] if line.strip()]
+        assert len(data_lines) <= VANTAGE_MAX_ROWS_PER_UPLOAD