Add public C-API header for dpctl_ext

Author: vlad-perevezentsev

CMakeLists.txt

@@ -344,14 +344,20 @@ if(DEFINED SKBUILD)
     set(_ignore_me ${SKBUILD})
 endif()
 
-# TODO: Replace `${CMAKE_BINARY_DIR}` with a dedicated public include root
-# for dpctl_ext C-API headers
-# Unlike dpctl which exposes C-API from `dpctl/apis/include`,
-# dpctl_ext currently relies on generated headers in the build tree.
-# `${CMAKE_BINARY_DIR}` is a temporary workaround.
+# DpctlExtCAPI: Interface library for dpctl_ext C-API
+# Provides access to:
+# 1. Public C-API headers from dpctl_ext/apis/include
+# 2. Generated Cython headers from the build directory
+#
+# This follows the same pattern as dpctl's DpctlCAPI interface library
 
 add_library(DpctlExtCAPI INTERFACE)
-target_include_directories(DpctlExtCAPI INTERFACE ${CMAKE_BINARY_DIR})
+target_include_directories(
+    DpctlExtCAPI
+    INTERFACE
+        ${CMAKE_CURRENT_SOURCE_DIR}/dpctl_ext/apis/include
+        ${CMAKE_BINARY_DIR} # For generated Cython headers
+)
 
 add_subdirectory(dpctl_ext)
 add_subdirectory(dpnp)

dpctl_ext/CMakeLists.txt

@@ -197,4 +197,12 @@ function(build_dpctl_ext _trgt _src _dest)
     target_include_directories(${_trgt_headers} INTERFACE ${_trgt_headers_dir})
 endfunction()
 
+# Install dpctl_ext C-API headers (similar to dpctl's C-API installation)
+install(
+    DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/apis/include/
+    DESTINATION ${CMAKE_INSTALL_PREFIX}/dpctl_ext/include
+    FILES_MATCHING
+    REGEX "\\.h(pp)?$"
+)
+
 add_subdirectory(tensor)

dpctl_ext/apis/include/dpctl_ext_capi.h

@@ -0,0 +1,37 @@
+//===----------- dpctl_ext_capi.h - Headers for dpctl_ext C-API  -*-C++-*-===//
+//
+//                   Data Parallel Extension for NumPy (dpnp)
+//
+// Copyright 2026 Intel Corporation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file provides access to dpctl_ext's C-API, primarily for accessing
+/// usm_ndarray types generated by Cython.
+///
+/// The generated Cython headers are located in the build directory at:
+///   ${CMAKE_BINARY_DIR}/dpctl_ext/tensor/
+///
+/// This header serves as the public API entry point and should be included
+/// instead of directly including the generated headers.
+//===----------------------------------------------------------------------===//
+
+#pragma once
+
+// Include the generated Cython C-API headers for usm_ndarray
+// These headers are generated during build and placed in the build directory
+#include <dpctl_ext/tensor/_usmarray.h>
+#include <dpctl_ext/tensor/_usmarray_api.h>

dpnp/backend/include/dpnp4pybind11.hpp

@@ -63,10 +63,9 @@
 
 // clang-format on
 
-// TODO: Keep these includes once `dpctl.tensor` is removed from dpctl,
-// but replace the hardcoded relative path with a proper include pathы
-#include <dpctl_ext/tensor/_usmarray.h>
-#include <dpctl_ext/tensor/_usmarray_api.h>
+// Include dpctl_ext C-API (provides access to usm_ndarray types)
+// This uses the public API header from dpctl_ext/apis/include
+#include "dpctl_ext_capi.h"
 
 /*
  * Function to import dpctl and make C-API functions available.