move batchsize from public header to internal

Author: mfoerste4

cpp/include/cuvs/neighbors/cagra.hpp

@@ -3300,9 +3300,6 @@ void optimize(raft::resources const& handle,
               raft::host_matrix_view<uint32_t, int64_t, raft::row_major> knn_graph,
               raft::host_matrix_view<uint32_t, int64_t, raft::row_major> new_graph);
 
-/** The batch size for the CAGRA optimize stage. */
-constexpr static size_t kOptimizeBatchSize = 256 * 1024;
-
 }  // namespace helpers
 }  // namespace cagra
 }  // namespace neighbors

cpp/src/neighbors/detail/cagra/cagra_helpers.cpp

@@ -3,6 +3,8 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+#include "cagra_helpers.hpp"
+
 #include <algorithm>
 #include <cstdint>
 #include <cuvs/neighbors/cagra.hpp>

cpp/src/neighbors/detail/cagra/cagra_helpers.hpp

@@ -0,0 +1,14 @@
+/*
+ * SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#pragma once
+
+#include <cstddef>
+
+namespace cuvs::neighbors::cagra::helpers {
+
+/** The batch size for the CAGRA optimize stage. */
+constexpr static size_t kOptimizeBatchSize = 256 * 1024;
+
+}  // namespace cuvs::neighbors::cagra::helpers

cpp/src/neighbors/detail/cagra/graph_core.cuh

@@ -4,6 +4,7 @@
  */
 #pragma once
 
+#include "cagra_helpers.hpp"
 #include "utils.hpp"
 
 #include <raft/core/copy.cuh>