diff --git a/.github/actions/setup-macos-toolchain/action.yml b/.github/actions/setup-macos-toolchain/action.yml
index 51da2f8f3..04b61ef78 100644
--- a/.github/actions/setup-macos-toolchain/action.yml
+++ b/.github/actions/setup-macos-toolchain/action.yml
@@ -1,5 +1,5 @@
 name: 'Setup macOS Toolchain'
-description: 'Configure Xcode, Homebrew packages, MPI, LLVM, OpenMP, OpenSSL, and ninja'
+description: 'Configure Xcode, Homebrew packages, LLVM, OpenMP, OpenSSL, and ninja'
 runs:
   using: 'composite'
   steps:
@@ -11,5 +11,5 @@ runs:
       shell: bash
       run: |
         brew update
-        brew install ninja mpich llvm libomp openssl
+        brew install ninja llvm libomp openssl
         brew link libomp --overwrite --force
diff --git a/.github/actions/setup-mpi-extensions/action.yml b/.github/actions/setup-mpi-extensions/action.yml
new file mode 100644
index 000000000..d46d2e182
--- /dev/null
+++ b/.github/actions/setup-mpi-extensions/action.yml
@@ -0,0 +1,27 @@
+name: Setup MPI Extensions Open MPI
+description: Install Open MPI from the mpi-extensions main prerelease
+inputs:
+  prefix:
+    description: Installation prefix. Defaults to $RUNNER_TEMP/mpi-extensions-openmpi.
+    default: ''
+  platform:
+    description: mpi-extensions platform name
+    default: auto
+  purge-system-mpi:
+    description: Remove package-manager MPI installations before installing mpi-extensions
+    default: 'false'
+runs:
+  using: composite
+  steps:
+    - name: Setup MPI extensions Open MPI
+      shell: bash
+      env:
+        GITHUB_TOKEN: ${{ github.token }}
+      run: >-
+        python3 "${GITHUB_WORKSPACE:-$PWD}/scripts/setup_mpi_extensions.py"
+        --repo-root "${GITHUB_WORKSPACE:-$PWD}"
+        --prefix "${{ inputs.prefix }}"
+        --platform "${{ inputs.platform }}"
+        --purge-system-mpi "${{ inputs.purge-system-mpi }}"
+        --github-env "$GITHUB_ENV"
+        --runner-temp "${RUNNER_TEMP:-${TMPDIR:-/tmp}}"
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
index 6f15a033b..55dd470fc 100644
--- a/.github/workflows/codeql.yml
+++ b/.github/workflows/codeql.yml
@@ -30,7 +30,7 @@ jobs:
       - name: Setup environment
         run: |
           sudo apt-get update
-          sudo apt-get install -y gcc-15 g++-15 ninja-build mpich libomp-dev valgrind
+          sudo apt-get install -y gcc-15 g++-15 ninja-build libomp-dev valgrind
           python3 -m pip install -r requirements.txt
       - name: ccache
         uses: hendrikmuhs/ccache-action@v1.2
@@ -38,6 +38,12 @@ jobs:
           key: ${{ runner.os }}-gcc
           create-symlink: true
           max-size: 1G
+      - name: Setup MPI extensions Open MPI
+        if: matrix.language == 'cpp'
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v4
         with:
@@ -47,6 +53,7 @@ jobs:
         run: >
           cmake -S . -B build -G Ninja
           -D CMAKE_BUILD_TYPE=RELEASE
+          -D PPC_MPI_EXTENSIONS_HOME="$PPC_MPI_EXTENSIONS_HOME"
         env:
           CC: gcc-15
           CXX: g++-15
diff --git a/.github/workflows/mac.yml b/.github/workflows/mac.yml
index 8b330f92b..9b5873b1c 100644
--- a/.github/workflows/mac.yml
+++ b/.github/workflows/mac.yml
@@ -24,6 +24,11 @@ jobs:
           submodules: recursive
       - name: Setup macOS toolchain
         uses: ./.github/actions/setup-macos-toolchain
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: macos-arm64
+          purge-system-mpi: 'true'
       - name: ccache
         uses: hendrikmuhs/ccache-action@v1.2
         with:
@@ -36,6 +41,7 @@ jobs:
           -DCMAKE_C_FLAGS="-I$(brew --prefix)/opt/libomp/include"
           -DCMAKE_CXX_FLAGS="-I$(brew --prefix)/opt/libomp/include"
           -D CMAKE_BUILD_TYPE=${{ matrix.build_type }} -DCMAKE_INSTALL_PREFIX=install
+          -D PPC_MPI_EXTENSIONS_HOME="$PPC_MPI_EXTENSIONS_HOME"
           -D PPC_TASKS="${{ inputs.ppc_tasks }}"
       - name: Build project
         run: |
@@ -58,13 +64,18 @@ jobs:
       - uses: actions/checkout@v6
       - name: Setup macOS toolchain
         uses: ./.github/actions/setup-macos-toolchain
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: macos-arm64
+          purge-system-mpi: 'true'
       - name: Download installed package
         uses: ./.github/actions/download-install
         with:
           path: install
           name: macos-clang-install
       - name: Run func tests (MPI)
-        run: scripts/run_tests.py --running-type="processes" --counts 1 2 3 4
+        run: scripts/run_tests.py --running-type="processes" --counts 1 2 3 4 --additional-mpi-args="--oversubscribe"
         env:
           PPC_NUM_THREADS: 1
           PPC_TASK_MAX_TIME: 30
@@ -80,6 +91,11 @@ jobs:
       - uses: actions/checkout@v6
       - name: Setup macOS toolchain
         uses: ./.github/actions/setup-macos-toolchain
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: macos-arm64
+          purge-system-mpi: 'true'
       - name: Download installed package
         uses: ./.github/actions/download-install
         with:
diff --git a/.github/workflows/perf.yml b/.github/workflows/perf.yml
index 9452b3d84..812e7e5e8 100644
--- a/.github/workflows/perf.yml
+++ b/.github/workflows/perf.yml
@@ -20,6 +20,11 @@ jobs:
       - name: Setup environment
         run: |
           python3 -m pip install -r requirements.txt --break-system-packages --ignore-installed
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
       - name: Download installed package
         uses: ./.github/actions/download-install
         with:
@@ -47,6 +52,11 @@ jobs:
       - uses: actions/checkout@v6
       - name: Setup macOS toolchain
         uses: ./.github/actions/setup-macos-toolchain
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: macos-arm64
+          purge-system-mpi: 'true'
       - name: Setup environment
         run: |
           python3 -m pip install -r requirements.txt --break-system-packages
diff --git a/.github/workflows/static-analysis-pr.yml b/.github/workflows/static-analysis-pr.yml
index fa40d6623..aa8b470d1 100644
--- a/.github/workflows/static-analysis-pr.yml
+++ b/.github/workflows/static-analysis-pr.yml
@@ -10,8 +10,12 @@ on:
       - '**/CMakeLists.txt'
       - '**/*.cmake'
       - '**/.clang-tidy'
+      - '.github/actions/setup-mpi-extensions/**'
       - '.github/workflows/static-analysis-pr.yml'
       - 'scripts/check_task_backend_apis.py'
+      - 'scripts/install_mpi_extensions.py'
+      - 'scripts/setup_mpi_extensions.py'
+      - 'scripts/write_mpi_runtime_env.py'
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
@@ -66,10 +70,17 @@ jobs:
           create-symlink: true
           max-size: 1G
 
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
+
       - name: CMake configure
         run: >
           cmake -S . -B build -G Ninja
           -D CMAKE_BUILD_TYPE=RELEASE -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DCMAKE_COMPILE_WARNING_AS_ERROR=ON
+          -D PPC_MPI_EXTENSIONS_HOME="$PPC_MPI_EXTENSIONS_HOME"
           -D PPC_TASKS="${{ needs.ci-scope.outputs.ppc_tasks || 'all' }}"
         env:
           CC: clang-22
@@ -117,10 +128,17 @@ jobs:
           create-symlink: true
           max-size: 1G
 
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
+
       - name: CMake configure
         run: >
           cmake -S . -B build -G Ninja
           -D CMAKE_BUILD_TYPE=RELEASE -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DCMAKE_COMPILE_WARNING_AS_ERROR=ON
+          -D PPC_MPI_EXTENSIONS_HOME="$PPC_MPI_EXTENSIONS_HOME"
           -D PPC_TASKS="${{ needs.ci-scope.outputs.ppc_tasks || 'all' }}"
         env:
           CC: gcc-15
diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index 34a25dee1..c638be985 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -35,10 +35,16 @@ jobs:
           key: ${{ runner.os }}-gcc
           create-symlink: true
           max-size: 1G
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
       - name: CMake configure
         run: >
           cmake -S . -B build -G Ninja
           -D CMAKE_BUILD_TYPE=${{ matrix.build_type }} -DCMAKE_INSTALL_PREFIX=install
+          -D PPC_MPI_EXTENSIONS_HOME="$PPC_MPI_EXTENSIONS_HOME"
           -D PPC_TASKS="${{ inputs.ppc_tasks }}"
         env:
           CC: gcc-15
@@ -81,6 +87,11 @@ jobs:
         os: ["ubuntu-26.04"]
     steps:
       - uses: actions/checkout@v6
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
       - name: Download installed package
         uses: ./.github/actions/download-install
         with:
@@ -110,6 +121,11 @@ jobs:
         os: ["ubuntu-26.04"]
     steps:
       - uses: actions/checkout@v6
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
       - name: Download installed package
         uses: ./.github/actions/download-install
         with:
@@ -139,10 +155,16 @@ jobs:
           key: ${{ runner.os }}-clang
           create-symlink: true
           max-size: 1G
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
       - name: CMake configure
         run: >
           cmake -S . -B build -G Ninja
           -D CMAKE_BUILD_TYPE=RELEASE -DCMAKE_INSTALL_PREFIX=install
+          -D PPC_MPI_EXTENSIONS_HOME="$PPC_MPI_EXTENSIONS_HOME"
           -D PPC_TASKS="${{ inputs.ppc_tasks }}"
         env:
           CC: clang-22
@@ -177,6 +199,11 @@ jobs:
         os: ["ubuntu-26.04"]
     steps:
       - uses: actions/checkout@v6
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
       - name: Download installed package
         uses: ./.github/actions/download-install
         with:
@@ -206,6 +233,11 @@ jobs:
         os: ["ubuntu-26.04"]
     steps:
       - uses: actions/checkout@v6
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
       - name: Download installed package
         uses: ./.github/actions/download-install
         with:
@@ -237,12 +269,18 @@ jobs:
           key: ${{ runner.os }}-clang
           create-symlink: true
           max-size: 1G
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
       - name: CMake configure
         run: >
           cmake -S . -B build -G Ninja
           -D CMAKE_BUILD_TYPE=RelWithDebInfo
           -D ENABLE_ADDRESS_SANITIZER=ON -D ENABLE_UB_SANITIZER=ON -D ENABLE_LEAK_SANITIZER=ON
           -D CMAKE_INSTALL_PREFIX=install
+          -D PPC_MPI_EXTENSIONS_HOME="$PPC_MPI_EXTENSIONS_HOME"
           -D PPC_TASKS="${{ inputs.ppc_tasks }}"
         env:
           CC: clang-22
@@ -277,6 +315,11 @@ jobs:
         os: ["ubuntu-26.04"]
     steps:
       - uses: actions/checkout@v6
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
       - name: Download installed package
         uses: ./.github/actions/download-install
         with:
@@ -312,6 +355,11 @@ jobs:
         os: ["ubuntu-26.04"]
     steps:
       - uses: actions/checkout@v6
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
       - name: Download installed package
         uses: ./.github/actions/download-install
         with:
@@ -347,12 +395,18 @@ jobs:
           key: ${{ runner.os }}-gcc
           create-symlink: true
           max-size: 1G
+      - name: Setup MPI extensions Open MPI
+        uses: ./.github/actions/setup-mpi-extensions
+        with:
+          platform: linux-x86_64
+          purge-system-mpi: 'true'
       - name: CMake configure
         run: >
           cmake -S . -B build -G Ninja
           -D CMAKE_BUILD_TYPE=RELEASE
           -D CMAKE_VERBOSE_MAKEFILE=ON -D USE_COVERAGE=ON
           -DCMAKE_INSTALL_PREFIX=install
+          -D PPC_MPI_EXTENSIONS_HOME="$PPC_MPI_EXTENSIONS_HOME"
           -D PPC_TASKS="${{ inputs.ppc_tasks }}"
       - name: Build project
         run: |
@@ -375,7 +429,7 @@ jobs:
         run: |
           mkdir cov-report
           cd build
-          gcovr --gcov-executable `which gcov-15` \
+          gcovr --gcov-executable "$(which gcov-15)" \
                 -r ../ \
                 --exclude '.*3rdparty/.*' \
                 --exclude '/usr/.*' \
diff --git a/.gitignore b/.gitignore
index 5de0996c8..a5ec67e03 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 /build*
+/_deps/
 docs/build*
 /xml
 docs/xml
diff --git a/cmake/mpi.cmake b/cmake/mpi.cmake
index 498b5450d..17ece25f8 100644
--- a/cmake/mpi.cmake
+++ b/cmake/mpi.cmake
@@ -1,5 +1,82 @@
 include_guard()
 
+set(PPC_MPI_EXTENSIONS_HOME
+    ""
+    CACHE PATH "Path to an unpacked mpi-extensions Open MPI package")
+
+if(NOT WIN32)
+  find_package(Python REQUIRED COMPONENTS Interpreter)
+
+  if(NOT PPC_MPI_EXTENSIONS_HOME)
+    message(
+      FATAL_ERROR
+        "PPC_MPI_EXTENSIONS_HOME is required on Linux and macOS. "
+        "Install the mpi-extensions main Open MPI package and configure with "
+        "-DPPC_MPI_EXTENSIONS_HOME=/path/to/mpi-extensions-openmpi")
+  endif()
+
+  get_filename_component(PPC_MPI_EXTENSIONS_HOME "${PPC_MPI_EXTENSIONS_HOME}"
+                         REALPATH BASE_DIR "${CMAKE_SOURCE_DIR}")
+  set(PPC_MPI_EXTENSIONS_HOME
+      "${PPC_MPI_EXTENSIONS_HOME}"
+      CACHE PATH "Path to an unpacked mpi-extensions Open MPI package" FORCE)
+
+  set(_PPC_MPI_EXTENSIONS_BIN "${PPC_MPI_EXTENSIONS_HOME}/bin")
+  set(_PPC_MPI_EXTENSIONS_LIB "${PPC_MPI_EXTENSIONS_HOME}/lib")
+
+  foreach(tool mpicc mpicxx mpirun mpiexec)
+    if(NOT EXISTS "${_PPC_MPI_EXTENSIONS_BIN}/${tool}")
+      message(
+        FATAL_ERROR
+          "PPC_MPI_EXTENSIONS_HOME does not contain required tool '${tool}': "
+          "${_PPC_MPI_EXTENSIONS_BIN}/${tool}")
+    endif()
+  endforeach()
+
+  if(NOT IS_DIRECTORY "${_PPC_MPI_EXTENSIONS_LIB}")
+    message(
+      FATAL_ERROR "PPC_MPI_EXTENSIONS_HOME does not contain a lib directory: "
+                  "${_PPC_MPI_EXTENSIONS_LIB}")
+  endif()
+
+  set(MPI_C_COMPILER
+      "${_PPC_MPI_EXTENSIONS_BIN}/mpicc"
+      CACHE FILEPATH "mpi-extensions C MPI wrapper" FORCE)
+  set(MPI_CXX_COMPILER
+      "${_PPC_MPI_EXTENSIONS_BIN}/mpicxx"
+      CACHE FILEPATH "mpi-extensions CXX MPI wrapper" FORCE)
+  set(MPIEXEC_EXECUTABLE
+      "${_PPC_MPI_EXTENSIONS_BIN}/mpirun"
+      CACHE FILEPATH "mpi-extensions MPI launcher" FORCE)
+  set(MPIEXEC_NUMPROC_FLAG
+      "-np"
+      CACHE STRING "MPI process count flag" FORCE)
+
+  list(PREPEND CMAKE_PREFIX_PATH "${PPC_MPI_EXTENSIONS_HOME}")
+  list(PREPEND CMAKE_BUILD_RPATH "${_PPC_MPI_EXTENSIONS_LIB}")
+  list(PREPEND CMAKE_INSTALL_RPATH "${_PPC_MPI_EXTENSIONS_LIB}")
+
+  set(_PPC_MPI_RUNTIME_CONFIG "${CMAKE_BINARY_DIR}/ppc_mpi_runtime_env.json")
+  execute_process(
+    COMMAND
+      "${Python_EXECUTABLE}"
+      "${CMAKE_SOURCE_DIR}/scripts/write_mpi_runtime_env.py" --output
+      "${_PPC_MPI_RUNTIME_CONFIG}" --mpi-extensions-home
+      "${PPC_MPI_EXTENSIONS_HOME}" --mpi-exec "${MPIEXEC_EXECUTABLE}"
+      --path-prepend "${_PPC_MPI_EXTENSIONS_BIN}" --library-path-prepend
+      "${_PPC_MPI_EXTENSIONS_LIB}"
+    RESULT_VARIABLE _PPC_MPI_RUNTIME_CONFIG_RESULT
+    OUTPUT_VARIABLE _PPC_MPI_RUNTIME_CONFIG_OUTPUT
+    ERROR_VARIABLE _PPC_MPI_RUNTIME_CONFIG_ERROR)
+  if(NOT _PPC_MPI_RUNTIME_CONFIG_RESULT EQUAL 0)
+    message(
+      FATAL_ERROR
+        "Failed to write MPI runtime config:\n"
+        "${_PPC_MPI_RUNTIME_CONFIG_OUTPUT}${_PPC_MPI_RUNTIME_CONFIG_ERROR}")
+  endif()
+  install(FILES "${_PPC_MPI_RUNTIME_CONFIG}" DESTINATION ".")
+endif()
+
 find_package(MPI REQUIRED COMPONENTS CXX)
 if(NOT MPI_FOUND)
   message(FATAL_ERROR "MPI NOT FOUND")
diff --git a/docker/ubuntu.Dockerfile b/docker/ubuntu.Dockerfile
index a4aaed63a..3c5900cce 100644
--- a/docker/ubuntu.Dockerfile
+++ b/docker/ubuntu.Dockerfile
@@ -12,8 +12,6 @@ RUN set -e \
     ninja-build cmake make \
     ccache \
     valgrind \
-    libmpich-dev mpich \
-    openmpi-bin openmpi-common libopenmpi-dev \
     libomp-dev \
     gcc-15 g++-15 \
     gcovr zip \
diff --git a/docs/locale/en/LC_MESSAGES/user_guide/environment.po b/docs/locale/en/LC_MESSAGES/user_guide/environment.po
index a2b01b1c0..95a3fbba2 100644
--- a/docs/locale/en/LC_MESSAGES/user_guide/environment.po
+++ b/docs/locale/en/LC_MESSAGES/user_guide/environment.po
@@ -20,7 +20,7 @@ msgstr ""
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=utf-8\n"
 "Content-Transfer-Encoding: 8bit\n"
-"Generated-By: Babel 2.17.0\n"
+"Generated-By: Babel 2.18.0\n"
 
 #: ../../../../docs/user_guide/environment.rst:2
 msgid "Set Up Your Environment"
@@ -80,145 +80,149 @@ msgid "The container includes:"
 msgstr ""
 
 #: ../../../../docs/user_guide/environment.rst:21
-msgid "Ubuntu environment with gcc-15, CMake, MPI, OpenMP"
+msgid "Ubuntu environment with gcc-15, CMake, OpenMP"
 msgstr ""
 
 #: ../../../../docs/user_guide/environment.rst:22
-msgid "Pre-configured C++ and Python development tools"
+msgid "Open MPI from the ``learning-process/mpi-extensions`` main prerelease"
 msgstr ""
 
 #: ../../../../docs/user_guide/environment.rst:23
+msgid "Pre-configured C++ and Python development tools"
+msgstr ""
+
+#: ../../../../docs/user_guide/environment.rst:24
 msgid "All project dependencies ready to use"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:25
+#: ../../../../docs/user_guide/environment.rst:26
 msgid ""
 "This provides a consistent development environment across all platforms "
 "without manual dependency installation."
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:28
+#: ../../../../docs/user_guide/environment.rst:29
 msgid "Manual Setup"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:30
+#: ../../../../docs/user_guide/environment.rst:31
 msgid ""
 "If you prefer manual setup or cannot use containers, follow the "
 "instructions below."
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:33
+#: ../../../../docs/user_guide/environment.rst:34
 msgid "Build prerequisites"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:34
+#: ../../../../docs/user_guide/environment.rst:35
 msgid ""
 "**Windows**: Download and install CMake from https://cmake.org/download "
 "(select the Windows installer) or install using Chocolatey:"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:40
+#: ../../../../docs/user_guide/environment.rst:41
 msgid "**Linux (Ubuntu/Debian)**: Install using package manager:"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:47
+#: ../../../../docs/user_guide/environment.rst:48
 msgid "**macOS**: Install using Homebrew:"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:55
+#: ../../../../docs/user_guide/environment.rst:56
 msgid "Code Style Analysis"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:56
+#: ../../../../docs/user_guide/environment.rst:57
 msgid ""
 "Please follow the `Google C++ Style Guide "
 "<https://google.github.io/styleguide/cppguide.html>`_."
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:58
+#: ../../../../docs/user_guide/environment.rst:59
 msgid ""
 "Code style is checked using the `clang-format "
 "<https://clang.llvm.org/docs/ClangFormat.html>`_ tool."
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:61
+#: ../../../../docs/user_guide/environment.rst:62
 msgid "Optional tools (clang-tidy, gcovr)"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:62
+#: ../../../../docs/user_guide/environment.rst:63
 msgid ""
 "Install these to match the CI toolchain for static analysis and coverage "
 "reports."
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:64
+#: ../../../../docs/user_guide/environment.rst:65
 msgid "Linux (Ubuntu/Debian):"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:75
+#: ../../../../docs/user_guide/environment.rst:74
 msgid "macOS (Homebrew):"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:83
+#: ../../../../docs/user_guide/environment.rst:82
 msgid "Windows:"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:92
+#: ../../../../docs/user_guide/environment.rst:91
 msgid "Parallel Programming Technologies"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:95
+#: ../../../../docs/user_guide/environment.rst:94
 msgid "``MPI``"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:96
+#: ../../../../docs/user_guide/environment.rst:95
 msgid "**Windows (MSVC)**:"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:98
+#: ../../../../docs/user_guide/environment.rst:97
 msgid ""
 "`Installers link <https://www.microsoft.com/en-"
 "us/download/details.aspx?id=105289>`_. You have to install "
 "``msmpisdk.msi`` and ``msmpisetup.exe``."
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:100
-#: ../../../../docs/user_guide/environment.rst:116
+#: ../../../../docs/user_guide/environment.rst:99
+#: ../../../../docs/user_guide/environment.rst:119
 msgid "**Linux (gcc and clang)**:"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:106
+#: ../../../../docs/user_guide/environment.rst:107
 msgid "**MacOS (apple clang)**:"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:113
+#: ../../../../docs/user_guide/environment.rst:116
 msgid "``OpenMP``"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:114
+#: ../../../../docs/user_guide/environment.rst:117
 msgid ""
 "``OpenMP`` is included in ``gcc`` and ``msvc``, but some components "
 "should be installed additionally:"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:122
+#: ../../../../docs/user_guide/environment.rst:125
 msgid "**MacOS (llvm)**:"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:130
+#: ../../../../docs/user_guide/environment.rst:134
 msgid "``TBB``"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:131
+#: ../../../../docs/user_guide/environment.rst:135
 msgid ""
 "**Windows (MSVC)**, **Linux (gcc and clang)**, **MacOS (apple clang)**: "
 "Build as 3rdparty in the current project."
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:135
+#: ../../../../docs/user_guide/environment.rst:139
 msgid "``std::thread``"
 msgstr ""
 
-#: ../../../../docs/user_guide/environment.rst:136
+#: ../../../../docs/user_guide/environment.rst:140
 msgid "``std::thread`` is included in STL libraries."
 msgstr ""
diff --git a/docs/locale/ru/LC_MESSAGES/user_guide/environment.po b/docs/locale/ru/LC_MESSAGES/user_guide/environment.po
index 607dd1854..475ca67a6 100644
--- a/docs/locale/ru/LC_MESSAGES/user_guide/environment.po
+++ b/docs/locale/ru/LC_MESSAGES/user_guide/environment.po
@@ -20,7 +20,7 @@ msgstr ""
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=utf-8\n"
 "Content-Transfer-Encoding: 8bit\n"
-"Generated-By: Babel 2.17.0\n"
+"Generated-By: Babel 2.18.0\n"
 
 #: ../../../../docs/user_guide/environment.rst:2
 msgid "Set Up Your Environment"
@@ -89,18 +89,22 @@ msgid "The container includes:"
 msgstr "Контейнер включает:"
 
 #: ../../../../docs/user_guide/environment.rst:21
-msgid "Ubuntu environment with gcc-15, CMake, MPI, OpenMP"
-msgstr "Окружение Ubuntu с gcc-15, CMake, MPI, OpenMP"
+msgid "Ubuntu environment with gcc-15, CMake, OpenMP"
+msgstr "Окружение Ubuntu с gcc-15, CMake и OpenMP"
 
 #: ../../../../docs/user_guide/environment.rst:22
+msgid "Open MPI from the ``learning-process/mpi-extensions`` main prerelease"
+msgstr "Open MPI из основного предварительного релиза ``learning-process/mpi-extensions``"
+
+#: ../../../../docs/user_guide/environment.rst:23
 msgid "Pre-configured C++ and Python development tools"
 msgstr "Предварительно настроенные инструменты разработки C++ и Python"
 
-#: ../../../../docs/user_guide/environment.rst:23
+#: ../../../../docs/user_guide/environment.rst:24
 msgid "All project dependencies ready to use"
 msgstr "Все зависимости проекта готовы к использованию"
 
-#: ../../../../docs/user_guide/environment.rst:25
+#: ../../../../docs/user_guide/environment.rst:26
 msgid ""
 "This provides a consistent development environment across all platforms "
 "without manual dependency installation."
@@ -108,11 +112,11 @@ msgstr ""
 "Это обеспечивает единообразную среду разработки на всех платформах без "
 "ручной установки зависимостей."
 
-#: ../../../../docs/user_guide/environment.rst:28
+#: ../../../../docs/user_guide/environment.rst:29
 msgid "Manual Setup"
 msgstr "Ручная настройка"
 
-#: ../../../../docs/user_guide/environment.rst:30
+#: ../../../../docs/user_guide/environment.rst:31
 msgid ""
 "If you prefer manual setup or cannot use containers, follow the "
 "instructions below."
@@ -120,11 +124,11 @@ msgstr ""
 "Если вы предпочитаете ручную настройку или не можете использовать "
 "контейнеры, следуйте инструкциям ниже."
 
-#: ../../../../docs/user_guide/environment.rst:33
+#: ../../../../docs/user_guide/environment.rst:34
 msgid "Build prerequisites"
 msgstr "Требования к сборке"
 
-#: ../../../../docs/user_guide/environment.rst:34
+#: ../../../../docs/user_guide/environment.rst:35
 msgid ""
 "**Windows**: Download and install CMake from https://cmake.org/download "
 "(select the Windows installer) or install using Chocolatey:"
@@ -132,19 +136,19 @@ msgstr ""
 "**Windows**: Загрузите и установите CMake с https://cmake.org/download "
 "(выберите установщик для Windows) или установите с помощью Chocolatey:"
 
-#: ../../../../docs/user_guide/environment.rst:40
+#: ../../../../docs/user_guide/environment.rst:41
 msgid "**Linux (Ubuntu/Debian)**: Install using package manager:"
 msgstr "**Linux (Ubuntu/Debian)**: Установите с помощью менеджера пакетов:"
 
-#: ../../../../docs/user_guide/environment.rst:47
+#: ../../../../docs/user_guide/environment.rst:48
 msgid "**macOS**: Install using Homebrew:"
 msgstr "**macOS**: Установите с помощью Homebrew:"
 
-#: ../../../../docs/user_guide/environment.rst:55
+#: ../../../../docs/user_guide/environment.rst:56
 msgid "Code Style Analysis"
 msgstr "Анализ стиля кодирования"
 
-#: ../../../../docs/user_guide/environment.rst:56
+#: ../../../../docs/user_guide/environment.rst:57
 msgid ""
 "Please follow the `Google C++ Style Guide "
 "<https://google.github.io/styleguide/cppguide.html>`_."
@@ -152,7 +156,7 @@ msgstr ""
 "Пожалуйста пройдите по ссылке для изучения стиля кодирования - `Google "
 "C++ Style Guide <https://google.github.io/styleguide/cppguide.html>`_."
 
-#: ../../../../docs/user_guide/environment.rst:58
+#: ../../../../docs/user_guide/environment.rst:59
 msgid ""
 "Code style is checked using the `clang-format "
 "<https://clang.llvm.org/docs/ClangFormat.html>`_ tool."
@@ -160,41 +164,43 @@ msgstr ""
 "Проверка стиля кода выполняется с помощью инструмента `clang-format "
 "<https://clang.llvm.org/docs/ClangFormat.html>`_."
 
-#: ../../../../docs/user_guide/environment.rst:61
+#: ../../../../docs/user_guide/environment.rst:62
 msgid "Optional tools (clang-tidy, gcovr)"
 msgstr "Дополнительные инструменты (clang-tidy, gcovr)"
 
-#: ../../../../docs/user_guide/environment.rst:62
+#: ../../../../docs/user_guide/environment.rst:63
 msgid ""
 "Install these to match the CI toolchain for static analysis and coverage "
 "reports."
-msgstr "Установите их, чтобы соответствовать инструментам CI для статического анализа и отчётов по покрытию."
+msgstr ""
+"Установите их, чтобы соответствовать инструментам CI для статического "
+"анализа и отчётов по покрытию."
 
-#: ../../../../docs/user_guide/environment.rst:64
+#: ../../../../docs/user_guide/environment.rst:65
 msgid "Linux (Ubuntu/Debian):"
 msgstr "Linux (Ubuntu/Debian):"
 
-#: ../../../../docs/user_guide/environment.rst:75
+#: ../../../../docs/user_guide/environment.rst:74
 msgid "macOS (Homebrew):"
 msgstr "macOS (Homebrew):"
 
-#: ../../../../docs/user_guide/environment.rst:83
+#: ../../../../docs/user_guide/environment.rst:82
 msgid "Windows:"
 msgstr "Windows:"
 
-#: ../../../../docs/user_guide/environment.rst:92
+#: ../../../../docs/user_guide/environment.rst:91
 msgid "Parallel Programming Technologies"
 msgstr "Технологии параллельного программирования"
 
-#: ../../../../docs/user_guide/environment.rst:95
+#: ../../../../docs/user_guide/environment.rst:94
 msgid "``MPI``"
 msgstr "``MPI``"
 
-#: ../../../../docs/user_guide/environment.rst:96
+#: ../../../../docs/user_guide/environment.rst:95
 msgid "**Windows (MSVC)**:"
 msgstr "**Windows (MSVC)**:"
 
-#: ../../../../docs/user_guide/environment.rst:98
+#: ../../../../docs/user_guide/environment.rst:97
 msgid ""
 "`Installers link <https://www.microsoft.com/en-"
 "us/download/details.aspx?id=105289>`_. You have to install "
@@ -204,20 +210,20 @@ msgstr ""
 "us/download/details.aspx?id=105289>`_. Вы должны установить 2 файла - "
 "``msmpisdk.msi`` и ``msmpisetup.exe``."
 
-#: ../../../../docs/user_guide/environment.rst:100
-#: ../../../../docs/user_guide/environment.rst:116
+#: ../../../../docs/user_guide/environment.rst:99
+#: ../../../../docs/user_guide/environment.rst:119
 msgid "**Linux (gcc and clang)**:"
 msgstr "**Linux (gcc and clang)**:"
 
-#: ../../../../docs/user_guide/environment.rst:106
+#: ../../../../docs/user_guide/environment.rst:107
 msgid "**MacOS (apple clang)**:"
 msgstr "**MacOS (apple clang)**:"
 
-#: ../../../../docs/user_guide/environment.rst:113
+#: ../../../../docs/user_guide/environment.rst:116
 msgid "``OpenMP``"
 msgstr "``OpenMP``"
 
-#: ../../../../docs/user_guide/environment.rst:114
+#: ../../../../docs/user_guide/environment.rst:117
 msgid ""
 "``OpenMP`` is included in ``gcc`` and ``msvc``, but some components "
 "should be installed additionally:"
@@ -226,15 +232,15 @@ msgstr ""
 "``msvc``, но ряд компонент все равно должны быть установлены "
 "дополнительно:"
 
-#: ../../../../docs/user_guide/environment.rst:122
+#: ../../../../docs/user_guide/environment.rst:125
 msgid "**MacOS (llvm)**:"
 msgstr "**MacOS (llvm)**:"
 
-#: ../../../../docs/user_guide/environment.rst:130
+#: ../../../../docs/user_guide/environment.rst:134
 msgid "``TBB``"
 msgstr "``TBB``"
 
-#: ../../../../docs/user_guide/environment.rst:131
+#: ../../../../docs/user_guide/environment.rst:135
 msgid ""
 "**Windows (MSVC)**, **Linux (gcc and clang)**, **MacOS (apple clang)**: "
 "Build as 3rdparty in the current project."
@@ -243,10 +249,10 @@ msgstr ""
 "Данная библиотека строится как внешняя в составе текущего проекта и не "
 "требует дополнительных операций."
 
-#: ../../../../docs/user_guide/environment.rst:135
+#: ../../../../docs/user_guide/environment.rst:139
 msgid "``std::thread``"
 msgstr "``std::thread``"
 
-#: ../../../../docs/user_guide/environment.rst:136
+#: ../../../../docs/user_guide/environment.rst:140
 msgid "``std::thread`` is included in STL libraries."
 msgstr "``std::thread`` включена в состав STL библиотек."
diff --git a/docs/user_guide/environment.rst b/docs/user_guide/environment.rst
index a8a653a38..2ebcb89b4 100644
--- a/docs/user_guide/environment.rst
+++ b/docs/user_guide/environment.rst
@@ -18,7 +18,8 @@ The easiest way to set up your development environment is using the provided ``.
 3. VS Code will automatically build the container with all dependencies pre-installed
 4. The container includes:
 
-   - Ubuntu environment with gcc-15, CMake, MPI, OpenMP
+   - Ubuntu environment with gcc-15, CMake, OpenMP
+   - Open MPI from the ``learning-process/mpi-extensions`` main prerelease
    - Pre-configured C++ and Python development tools
    - All project dependencies ready to use
 
@@ -96,29 +97,33 @@ Parallel Programming Technologies
   `Installers link <https://www.microsoft.com/en-us/download/details.aspx?id=105289>`_. You have to install ``msmpisdk.msi`` and ``msmpisetup.exe``.
 
 - **Linux (gcc and clang)**:
-  
+
   .. code-block:: bash
 
-     sudo apt install -y mpich openmpi-bin libopenmpi-dev
+     python3 -m pip install 'requests>=2.31,<3'
+     python3 scripts/install_mpi_extensions.py --prefix "$PWD/_deps/mpi-extensions-openmpi" --force
+     cmake -S . -B build -D PPC_MPI_EXTENSIONS_HOME="$PWD/_deps/mpi-extensions-openmpi"
 
 - **MacOS (apple clang)**:
-  
+
   .. code-block:: bash
 
-     brew install open-mpi
+     python3 -m pip install 'requests>=2.31,<3'
+     python3 scripts/install_mpi_extensions.py --prefix "$PWD/_deps/mpi-extensions-openmpi" --force
+     cmake -S . -B build -D PPC_MPI_EXTENSIONS_HOME="$PWD/_deps/mpi-extensions-openmpi"
 
 ``OpenMP``
 ~~~~~~~~~~
 ``OpenMP`` is included in ``gcc`` and ``msvc``, but some components should be installed additionally:
 
 - **Linux (gcc and clang)**:
-  
+
   .. code-block:: bash
 
      sudo apt install -y libomp-dev
 
 - **MacOS (llvm)**:
-  
+
   .. code-block:: bash
 
      brew install llvm
diff --git a/requirements.txt b/requirements.txt
index eb505ddfb..8439d388e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,3 +2,4 @@ numpy==2.4.6
 XlsxWriter==3.2.9
 PyYAML==6.0.3
 pre-commit==4.5.1
+requests>=2.31,<3
diff --git a/scripts/install_mpi_extensions.py b/scripts/install_mpi_extensions.py
new file mode 100755
index 000000000..72354278d
--- /dev/null
+++ b/scripts/install_mpi_extensions.py
@@ -0,0 +1,413 @@
+#!/usr/bin/env python3
+
+from __future__ import annotations
+
+import argparse
+import hashlib
+import os
+import platform
+import re
+import shutil
+import subprocess
+import sys
+import tarfile
+import tempfile
+from pathlib import Path, PurePosixPath
+from typing import Any
+
+try:
+    import requests
+except ImportError as exc:
+    raise SystemExit(
+        "Missing Python dependency 'requests'. Install it with: "
+        "python3 -m pip install 'requests>=2.31,<3'"
+    ) from exc
+
+
+DEFAULT_REPO = "learning-process/mpi-extensions"
+RELEASE_TAG = "main"
+SUPPORTED_PLATFORMS = {
+    "linux-x86_64",
+    "linux-arm64",
+    "macos-arm64",
+    "macos-x86_64",
+}
+
+
+def normalize_machine(machine: str) -> str:
+    normalized = machine.lower()
+    if normalized in {"x86_64", "amd64"}:
+        return "x86_64"
+    if normalized in {"arm64", "aarch64"}:
+        return "arm64"
+    return normalized
+
+
+def detect_platform() -> str:
+    system = platform.system()
+    machine = normalize_machine(platform.machine())
+    if system == "Linux":
+        return f"linux-{machine}"
+    if system == "Darwin":
+        return f"macos-{machine}"
+    raise SystemExit(f"Unsupported operating system for mpi-extensions: {system}")
+
+
+def parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(
+        description="Install Open MPI from the mpi-extensions main prerelease."
+    )
+    parser.add_argument("--repo", default=DEFAULT_REPO, help=f"default: {DEFAULT_REPO}")
+    parser.add_argument(
+        "--platform",
+        default="auto",
+        help="auto, linux-x86_64, linux-arm64, macos-arm64, or macos-x86_64",
+    )
+    parser.add_argument("--prefix", required=True, type=Path)
+    parser.add_argument(
+        "--force",
+        action="store_true",
+        help="remove an existing installation prefix before extracting",
+    )
+    return parser.parse_args()
+
+
+def github_headers() -> dict[str, str]:
+    headers = {
+        "Accept": "application/vnd.github+json",
+        "X-GitHub-Api-Version": "2022-11-28",
+        "User-Agent": "parallel-programming-course-mpi-extensions-installer",
+    }
+    token = os.environ.get("GITHUB_TOKEN")
+    if token:
+        headers["Authorization"] = f"Bearer {token}"
+    return headers
+
+
+def get_json(session: requests.Session, url: str) -> dict[str, Any]:
+    response = session.get(url, timeout=60)
+    if response.status_code == 404:
+        raise SystemExit(f"GitHub resource not found: {url}")
+    response.raise_for_status()
+    data = response.json()
+    if not isinstance(data, dict):
+        raise SystemExit(f"Unexpected GitHub API response from {url}")
+    return data
+
+
+def select_asset(release: dict[str, Any], asset_name: str) -> dict[str, Any]:
+    for asset in release.get("assets", []):
+        if asset.get("name") == asset_name:
+            return asset
+    available = ", ".join(
+        asset.get("name", "<unnamed>") for asset in release.get("assets", [])
+    )
+    raise SystemExit(
+        f"Release asset not found: {asset_name}. Available assets: {available}"
+    )
+
+
+def select_archive_asset(
+    release: dict[str, Any], target_platform: str
+) -> dict[str, Any]:
+    pattern = re.compile(
+        rf"^mpi-extensions-openmpi-.+-{re.escape(target_platform)}\.tar\.gz$"
+    )
+    matches = [
+        asset
+        for asset in release.get("assets", [])
+        if pattern.match(str(asset.get("name", "")))
+    ]
+    if len(matches) != 1:
+        available = ", ".join(
+            asset.get("name", "<unnamed>") for asset in release.get("assets", [])
+        )
+        raise SystemExit(
+            f"Expected exactly one main release archive for {target_platform}, "
+            f"found {len(matches)}. Available assets: {available}"
+        )
+    return matches[0]
+
+
+def download(session: requests.Session, url: str, destination: Path) -> None:
+    with session.get(url, stream=True, timeout=300) as response:
+        response.raise_for_status()
+        with destination.open("wb") as output:
+            for chunk in response.iter_content(chunk_size=1024 * 1024):
+                if chunk:
+                    output.write(chunk)
+
+
+def sha256sum(path: Path) -> str:
+    digest = hashlib.sha256()
+    with path.open("rb") as input_file:
+        for chunk in iter(lambda: input_file.read(1024 * 1024), b""):
+            digest.update(chunk)
+    return digest.hexdigest()
+
+
+def path_is_inside(path: Path, directory: Path) -> bool:
+    return path == directory or directory in path.parents
+
+
+def archive_member_path(member: tarfile.TarInfo) -> PurePosixPath:
+    member_path = PurePosixPath(member.name)
+    if member_path.is_absolute() or not member_path.parts:
+        raise SystemExit(f"Archive contains unsafe path: {member.name}")
+    if any(part in {"", ".", ".."} for part in member_path.parts):
+        raise SystemExit(f"Archive contains unsafe path: {member.name}")
+    return member_path
+
+
+def validate_archive_member_type(member: tarfile.TarInfo) -> None:
+    if member.isdir() or member.isfile() or member.issym() or member.islnk():
+        return
+    raise SystemExit(f"Archive contains unsupported member type: {member.name}")
+
+
+def validate_archive_link(
+    member: tarfile.TarInfo,
+    member_path: PurePosixPath,
+    destination: Path,
+    resolved_destination: Path,
+) -> None:
+    if not (member.issym() or member.islnk()):
+        return
+    if not member.linkname:
+        raise SystemExit(f"Archive contains empty link target: {member.name}")
+
+    link_path = PurePosixPath(member.linkname)
+    if link_path.is_absolute():
+        raise SystemExit(
+            f"Archive link target is absolute: {member.name} -> {member.linkname}"
+        )
+
+    member_target = (destination / Path(*member_path.parts)).resolve(strict=False)
+    if member.issym():
+        link_target = (member_target.parent / member.linkname).resolve(strict=False)
+    else:
+        link_target = (destination / member.linkname).resolve(strict=False)
+
+    if not path_is_inside(link_target, resolved_destination):
+        raise SystemExit(
+            f"Archive link target escapes destination: "
+            f"{member.name} -> {member.linkname}"
+        )
+
+
+def safe_extract(archive: Path, destination: Path) -> Path:
+    destination.mkdir(parents=True, exist_ok=True)
+    resolved_destination = destination.resolve()
+    with tarfile.open(archive, "r:gz") as tar:
+        members = tar.getmembers()
+        roots = set()
+        member_paths = []
+        for member in members:
+            member_path = archive_member_path(member)
+            validate_archive_member_type(member)
+            roots.add(member_path.parts[0])
+            member_paths.append((member, member_path))
+            target = (destination / Path(*member_path.parts)).resolve(strict=False)
+            if not path_is_inside(target, resolved_destination):
+                raise SystemExit(f"Archive contains unsafe path: {member.name}")
+            validate_archive_link(
+                member, member_path, destination, resolved_destination
+            )
+
+        symlink_paths = {
+            member_path for member, member_path in member_paths if member.issym()
+        }
+        for member, member_path in member_paths:
+            for symlink_path in symlink_paths:
+                if symlink_path in member_path.parents:
+                    raise SystemExit(
+                        f"Archive member is nested under a symlink: {member.name}"
+                    )
+
+        if len(roots) != 1:
+            raise SystemExit(
+                f"Expected archive to contain one top-level directory, found: {roots}"
+            )
+        tar.extractall(destination, members=members)
+    return destination / roots.pop()
+
+
+def install_tree(source_root: Path, prefix: Path, force: bool) -> None:
+    required_tools = ["mpicc", "mpicxx", "mpirun", "mpiexec"]
+    missing_tools = [
+        tool for tool in required_tools if not (source_root / "bin" / tool).exists()
+    ]
+    if missing_tools:
+        raise SystemExit(
+            f"Archive is missing required MPI tools: {', '.join(missing_tools)}"
+        )
+
+    if prefix.exists():
+        if not force and any(prefix.iterdir()):
+            raise SystemExit(
+                f"Installation prefix is not empty: {prefix}. Use --force to replace it."
+            )
+        shutil.rmtree(prefix)
+    prefix.parent.mkdir(parents=True, exist_ok=True)
+    shutil.copytree(source_root, prefix, symlinks=True)
+
+
+def run_tool(command: list[str]) -> subprocess.CompletedProcess[str]:
+    return subprocess.run(
+        command, check=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True
+    )
+
+
+def otool_lines(path: Path) -> list[str]:
+    result = run_tool(["otool", "-L", str(path)])
+    if result.returncode != 0:
+        return []
+    return result.stdout.splitlines()[1:]
+
+
+def patch_macos_install_names(prefix: Path) -> None:
+    if platform.system() != "Darwin":
+        return
+    if (
+        not shutil.which("install_name_tool")
+        or not shutil.which("otool")
+        or not shutil.which("codesign")
+    ):
+        raise SystemExit(
+            "macOS install_name_tool, otool, and codesign are required to install mpi-extensions"
+        )
+
+    lib_dir = prefix / "lib"
+    if not lib_dir.exists():
+        return
+
+    local_libs = {
+        path.name: path.resolve()
+        for path in lib_dir.iterdir()
+        if path.is_file() and not path.is_symlink() and ".dylib" in path.name
+    }
+    mach_o_candidates = [
+        path
+        for base_dir in (prefix / "bin", lib_dir)
+        if base_dir.exists()
+        for path in base_dir.iterdir()
+        if path.is_file() and not path.is_symlink()
+    ]
+    patched_paths: set[Path] = set()
+
+    for path in local_libs.values():
+        result = run_tool(["otool", "-D", str(path)])
+        if result.returncode != 0:
+            continue
+        install_names = [
+            line.strip() for line in result.stdout.splitlines()[1:] if line.strip()
+        ]
+        if install_names:
+            local_name = local_libs.get(Path(install_names[0]).name)
+            if local_name:
+                replacement = f"@rpath/{local_name.name}"
+                if install_names[0] != replacement:
+                    subprocess.run(
+                        [
+                            "install_name_tool",
+                            "-id",
+                            replacement,
+                            str(path),
+                        ],
+                        check=True,
+                    )
+                    patched_paths.add(path)
+
+    for path in mach_o_candidates:
+        for line in otool_lines(path):
+            dependency = line.strip().split(" (", 1)[0]
+            if not dependency.startswith("/"):
+                continue
+            local_dependency = local_libs.get(Path(dependency).name)
+            if local_dependency and dependency != str(local_dependency):
+                if path.parent.resolve() == lib_dir.resolve():
+                    replacement = f"@loader_path/{local_dependency.name}"
+                elif path.parent.resolve() == (prefix / "bin").resolve():
+                    replacement = f"@loader_path/../lib/{local_dependency.name}"
+                else:
+                    replacement = f"@rpath/{local_dependency.name}"
+                subprocess.run(
+                    [
+                        "install_name_tool",
+                        "-change",
+                        dependency,
+                        replacement,
+                        str(path),
+                    ],
+                    check=True,
+                )
+                patched_paths.add(path)
+
+    for path in patched_paths:
+        subprocess.run(
+            ["codesign", "--force", "--sign", "-", "--timestamp=none", str(path)],
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+            check=True,
+        )
+
+
+def print_environment(prefix: Path) -> None:
+    prefix_text = str(prefix)
+    print(f"PPC_MPI_EXTENSIONS_HOME={prefix_text}")
+    print(f"CMake option: -DPPC_MPI_EXTENSIONS_HOME={prefix_text}")
+
+
+def main() -> int:
+    args = parse_args()
+    target_platform = detect_platform() if args.platform == "auto" else args.platform
+    if target_platform not in SUPPORTED_PLATFORMS:
+        raise SystemExit(
+            f"Unsupported platform '{target_platform}'. Supported values: "
+            f"{', '.join(sorted(SUPPORTED_PLATFORMS))}"
+        )
+
+    session = requests.Session()
+    session.headers.update(github_headers())
+    release_url = (
+        f"https://api.github.com/repos/{args.repo}/releases/tags/{RELEASE_TAG}"
+    )
+    release = get_json(session, release_url)
+    if release.get("tag_name") != RELEASE_TAG or not release.get("prerelease"):
+        raise SystemExit(
+            f"Release {args.repo}@{RELEASE_TAG} is not the main prerelease"
+        )
+
+    archive_asset = select_archive_asset(release, target_platform)
+    archive_name = archive_asset["name"]
+    checksum_asset = select_asset(release, f"{archive_name}.sha256")
+
+    with tempfile.TemporaryDirectory(prefix="mpi-extensions-") as temp_dir_text:
+        temp_dir = Path(temp_dir_text)
+        archive_path = temp_dir / archive_name
+        checksum_path = temp_dir / f"{archive_name}.sha256"
+        print(
+            f"Downloading {archive_name} from {args.repo}@{RELEASE_TAG}",
+            file=sys.stderr,
+        )
+        download(session, archive_asset["browser_download_url"], archive_path)
+        download(session, checksum_asset["browser_download_url"], checksum_path)
+
+        expected_sha = checksum_path.read_text(encoding="utf-8").split()[0]
+        actual_sha = sha256sum(archive_path)
+        if actual_sha != expected_sha:
+            raise SystemExit(
+                f"SHA256 mismatch for {archive_name}: expected {expected_sha}, got {actual_sha}"
+            )
+
+        source_root = safe_extract(archive_path, temp_dir / "extract")
+        prefix = args.prefix.resolve()
+        install_tree(source_root, prefix, args.force)
+        patch_macos_install_names(prefix)
+
+    print_environment(args.prefix.resolve())
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/scripts/run_tests.py b/scripts/run_tests.py
index bdbfc2280..c0ec07773 100755
--- a/scripts/run_tests.py
+++ b/scripts/run_tests.py
@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 
+import json
 import os
 import platform
 import shlex
@@ -67,15 +68,12 @@ def __init__(self, build_dir="build", verbose=False):
             self.mpi_exec = "mpirun"
         self.platform = platform.system()
 
-        # Detect MPI implementation to choose compatible flags
-        self.mpi_env_mode = "unknown"  # one of: openmpi, mpich, unknown
-        self.mpi_np_flag = "-np"
         if self.platform == "Windows":
-            # MSMPI uses -env and -n
             self.mpi_env_mode = "mpich"
             self.mpi_np_flag = "-n"
         else:
-            self.mpi_env_mode, self.mpi_np_flag = self.__detect_mpi_impl()
+            self.mpi_env_mode = "unknown"
+            self.mpi_np_flag = "-np"
 
     @staticmethod
     def __get_project_path():
@@ -105,11 +103,15 @@ def setup_env(self, ppc_env):
             build_dir = project_path / build_dir
         self.__build_dir_path = build_dir
 
-        install_bin_dir = project_path / "install" / "bin"
+        install_dir = project_path / "install"
+        install_bin_dir = install_dir / "bin"
         if install_bin_dir.exists():
+            self.__apply_mpi_runtime_config(install_dir / "ppc_mpi_runtime_env.json")
             self.work_dir = install_bin_dir
+            self.__detect_configured_mpi()
             return
 
+        self.__apply_mpi_runtime_config(build_dir / "ppc_mpi_runtime_env.json")
         bin_dir = build_dir if build_dir.name == "bin" else build_dir / "bin"
         if not bin_dir.exists():
             raise FileNotFoundError(
@@ -117,6 +119,52 @@ def setup_env(self, ppc_env):
                 "Build the project or pass a correct '--build-dir' (e.g. 'build', 'build_seq', or 'build/bin')."
             )
         self.work_dir = bin_dir
+        self.__detect_configured_mpi()
+
+    def __prepend_env_path(self, name, value):
+        current = self.__ppc_env.get(name)
+        self.__ppc_env[name] = (
+            str(value) if not current else f"{value}{os.pathsep}{current}"
+        )
+
+    def __apply_mpi_runtime_config(self, config_path):
+        if self.platform == "Windows":
+            return
+
+        if not config_path.exists():
+            raise FileNotFoundError(
+                f"MPI runtime config not found: '{config_path}'. "
+                "Configure CMake with -DPPC_MPI_EXTENSIONS_HOME=/path/to/mpi-extensions-openmpi."
+            )
+
+        with config_path.open(encoding="utf-8") as input_file:
+            config = json.load(input_file)
+
+        env_values = config.get("env", {})
+        for name, value in env_values.items():
+            self.__ppc_env[name] = str(value)
+
+        path_prepend = config.get("path_prepend")
+        if path_prepend:
+            self.__prepend_env_path("PATH", path_prepend)
+
+        library_path_prepend = config.get("library_path_prepend")
+        if library_path_prepend:
+            self.__prepend_env_path("LD_LIBRARY_PATH", library_path_prepend)
+            self.__prepend_env_path("DYLD_LIBRARY_PATH", library_path_prepend)
+
+        mpi_exec = config.get("mpi_exec")
+        if mpi_exec:
+            mpi_exec_path = Path(mpi_exec)
+            if not mpi_exec_path.exists():
+                raise FileNotFoundError(
+                    f"Configured MPI launcher not found: '{mpi_exec_path}'"
+                )
+            self.mpi_exec = str(mpi_exec_path)
+
+    def __detect_configured_mpi(self):
+        if self.platform != "Windows":
+            self.mpi_env_mode, self.mpi_np_flag = self.__detect_mpi_impl()
 
     def __run_exec(self, command, extra_env=None):
         if self.verbose:
@@ -142,6 +190,7 @@ def __detect_mpi_impl(self):
                     stdout=subprocess.PIPE,
                     stderr=subprocess.STDOUT,
                     text=True,
+                    env=self.__ppc_env,
                 )
                 out = (proc.stdout or "").lower()
                 if out:
diff --git a/scripts/setup_mpi_extensions.py b/scripts/setup_mpi_extensions.py
new file mode 100755
index 000000000..53c1a9934
--- /dev/null
+++ b/scripts/setup_mpi_extensions.py
@@ -0,0 +1,183 @@
+#!/usr/bin/env python3
+
+from __future__ import annotations
+
+import argparse
+import os
+import platform
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+MPI_PACKAGES_LINUX = [
+    "mpich",
+    "libmpich-dev",
+    "openmpi-bin",
+    "openmpi-common",
+    "libopenmpi-dev",
+    "mpi-default-bin",
+    "mpi-default-dev",
+]
+MPI_PACKAGES_MACOS = ["mpich", "open-mpi"]
+
+
+def parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(
+        description="Set up mpi-extensions Open MPI for GitHub Actions."
+    )
+    parser.add_argument("--repo-root", required=True, type=Path)
+    parser.add_argument("--prefix", required=True)
+    parser.add_argument("--platform", required=True)
+    parser.add_argument("--purge-system-mpi", choices=["true", "false"], required=True)
+    parser.add_argument("--github-env", required=True, type=Path)
+    parser.add_argument("--runner-temp", required=True, type=Path)
+    return parser.parse_args()
+
+
+def run(
+    command: list[str], *, env: dict[str, str] | None = None, check: bool = True
+) -> subprocess.CompletedProcess[str]:
+    print("+ " + " ".join(command), flush=True)
+    return subprocess.run(command, check=check, env=env)
+
+
+def sudo_prefix() -> list[str] | None:
+    if os.geteuid() == 0:
+        return []
+    if shutil.which("sudo"):
+        return ["sudo"]
+    return None
+
+
+def purge_linux_mpi() -> None:
+    if not shutil.which("apt-get"):
+        return
+    sudo = sudo_prefix()
+    if sudo is None:
+        print("::warning::sudo is unavailable; skipping Linux MPI package removal")
+        return
+
+    apt_get = sudo + ["apt-get"]
+    run(apt_get + ["update"])
+    run(apt_get + ["purge", "-y"] + MPI_PACKAGES_LINUX, check=False)
+    run(apt_get + ["autoremove", "-y"], check=False)
+    if os.geteuid() == 0:
+        shutil.rmtree("/var/lib/apt/lists", ignore_errors=True)
+
+
+def purge_macos_mpi() -> None:
+    if not shutil.which("brew"):
+        return
+    for package in MPI_PACKAGES_MACOS:
+        if (
+            subprocess.run(
+                ["brew", "list", "--versions", package], check=False
+            ).returncode
+            == 0
+        ):
+            run(["brew", "uninstall", "--ignore-dependencies", "--force", package])
+
+
+def purge_system_mpi(enabled: bool) -> None:
+    if not enabled:
+        return
+    system = platform.system()
+    if system == "Linux":
+        purge_linux_mpi()
+    elif system == "Darwin":
+        purge_macos_mpi()
+
+
+def prepare_python(runner_temp: Path) -> Path:
+    venv_dir = runner_temp / "mpi-extensions-python"
+    python_bin = venv_dir / "bin" / "python"
+    try:
+        run([sys.executable, "-m", "venv", str(venv_dir)])
+        run([str(python_bin), "-m", "pip", "install", "--upgrade", "pip"])
+        run([str(python_bin), "-m", "pip", "install", "requests>=2.31,<3"])
+        return python_bin
+    except subprocess.CalledProcessError:
+        print(
+            "::warning::Python venv setup failed; trying the current interpreter with pip"
+        )
+        if (
+            subprocess.run(
+                [sys.executable, "-m", "pip", "install", "--user", "requests>=2.31,<3"],
+                check=False,
+            ).returncode
+            != 0
+        ):
+            run(
+                [
+                    sys.executable,
+                    "-m",
+                    "pip",
+                    "install",
+                    "--break-system-packages",
+                    "requests>=2.31,<3",
+                ]
+            )
+        return Path(sys.executable)
+
+
+def install_openmpi(args: argparse.Namespace, python_bin: Path) -> None:
+    installer = args.repo_root / "scripts" / "install_mpi_extensions.py"
+    if not installer.exists():
+        raise SystemExit(f"mpi-extensions installer not found: {installer}")
+    run(
+        [
+            str(python_bin),
+            str(installer),
+            "--platform",
+            args.platform,
+            "--prefix",
+            str(args.prefix),
+            "--force",
+        ]
+    )
+
+
+def append_github_environment(prefix: Path, github_env: Path) -> None:
+    with github_env.open("a", encoding="utf-8") as output:
+        output.write(f"PPC_MPI_EXTENSIONS_HOME={prefix}\n")
+
+
+def validate_openmpi(prefix: Path) -> None:
+    expected_bin = prefix / "bin"
+    env = os.environ.copy()
+    env["MPI_EXTENSIONS_HOME"] = str(prefix)
+    env["MPI_HOME"] = str(prefix)
+    env["OPAL_PREFIX"] = str(prefix)
+    env["OMPI_MCA_shmem"] = "mmap"
+    env["PATH"] = f"{expected_bin}:{env.get('PATH', '')}"
+    env["LD_LIBRARY_PATH"] = f"{prefix / 'lib'}:{env.get('LD_LIBRARY_PATH', '')}"
+    env["DYLD_LIBRARY_PATH"] = f"{prefix / 'lib'}:{env.get('DYLD_LIBRARY_PATH', '')}"
+
+    for tool in ("mpicc", "mpicxx", "mpirun", "mpiexec"):
+        actual = shutil.which(tool, path=env["PATH"])
+        expected = expected_bin / tool
+        if actual != str(expected):
+            raise SystemExit(f"{tool} resolves to {actual} instead of {expected}")
+
+    run([str(expected_bin / "mpirun"), "--version"], env=env)
+    run([str(expected_bin / "mpicc"), "--showme:version"], env=env)
+
+
+def main() -> int:
+    args = parse_args()
+    if args.prefix:
+        prefix = Path(args.prefix).resolve()
+    else:
+        prefix = (args.runner_temp / "mpi-extensions-openmpi").resolve()
+    args.prefix = prefix
+    purge_system_mpi(args.purge_system_mpi == "true")
+    python_bin = prepare_python(args.runner_temp)
+    install_openmpi(args, python_bin)
+    append_github_environment(prefix, args.github_env)
+    validate_openmpi(prefix)
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/scripts/write_mpi_runtime_env.py b/scripts/write_mpi_runtime_env.py
new file mode 100755
index 000000000..8c3dfd175
--- /dev/null
+++ b/scripts/write_mpi_runtime_env.py
@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+
+from __future__ import annotations
+
+import argparse
+import json
+from pathlib import Path
+
+
+def parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(
+        description="Write the PPC MPI runtime environment JSON file."
+    )
+    parser.add_argument("--output", required=True, type=Path)
+    parser.add_argument("--mpi-extensions-home", required=True)
+    parser.add_argument("--mpi-exec", required=True)
+    parser.add_argument("--path-prepend", required=True)
+    parser.add_argument("--library-path-prepend", required=True)
+    return parser.parse_args()
+
+
+def main() -> None:
+    args = parse_args()
+    runtime_config = {
+        "mpi_extensions_home": args.mpi_extensions_home,
+        "mpi_exec": args.mpi_exec,
+        "path_prepend": args.path_prepend,
+        "library_path_prepend": args.library_path_prepend,
+        "env": {
+            "MPI_EXTENSIONS_HOME": args.mpi_extensions_home,
+            "MPI_HOME": args.mpi_extensions_home,
+            "OPAL_PREFIX": args.mpi_extensions_home,
+            "OMPI_MCA_shmem": "mmap",
+        },
+    }
+
+    args.output.parent.mkdir(parents=True, exist_ok=True)
+    args.output.write_text(
+        json.dumps(runtime_config, indent=2) + "\n", encoding="utf-8"
+    )
+
+
+if __name__ == "__main__":
+    main()