Improve parsing of total header

Author: sciapanCA

src/tests/test_datasources.py

@@ -276,6 +276,23 @@ async def test_get_data_sources_filtered_hint_without_total_header(mock_get_api_
     assert "without a query" in payload["message"].lower()
 
 
+@pytest.mark.asyncio
+@patch('tools.datasources.get_api_key_from_context')
+async def test_get_data_sources_filtered_hint_with_malformed_total_header(mock_get_api_key):
+    """A malformed total header is treated as absent rather than raising."""
+    mock_get_api_key.return_value = "test-key"
+    mock_ctx, _ = _ctx_with_response(
+        [{"id": "repo-1", "name": "Repo", "type": "Repository", "relevanceReason": "checkout flow"}],
+        headers={"X-CodeAlive-Total-Data-Sources": "not-a-number"},
+    )
+
+    result = await get_data_sources(mock_ctx, alive_only=True, query="checkout")
+
+    payload = result
+    assert "omitted" in payload["message"].lower()
+    assert "without a query" in payload["message"].lower()
+
+
 @pytest.mark.asyncio
 @patch('tools.datasources.get_api_key_from_context')
 async def test_get_data_sources_all_relevant_hint_reports_no_omission(mock_get_api_key):

src/tools/datasources.py

@@ -37,8 +37,11 @@ def _relevance_message(data_sources: list, response) -> str:
         )
 
     shown = len(data_sources)
-    total_header = response.headers.get(_TOTAL_HEADER)
-    total = int(total_header) if total_header and total_header.isdigit() else None
+    try:
+        total = int(response.headers.get(_TOTAL_HEADER))
+    except (TypeError, ValueError):
+        # Header absent (TypeError on int(None)) or malformed (ValueError).
+        total = None
     if total is not None and total > shown:
         return (
             f"{shown} of {total} available data sources are relevant to this query; the other "