From df92778363fe695198b74796b649d9864170120b Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 30 Mar 2026 17:00:46 +0200
Subject: [PATCH 01/17] Improvement: Add Mac OS CI workflow

---
 .github/workflows/test_t8code_macos.yml | 168 ++++++++++++++++++++++++
 .github/workflows/testsuite.yml         |  23 ++++
 2 files changed, 191 insertions(+)
 create mode 100644 .github/workflows/test_t8code_macos.yml

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
new file mode 100644
index 0000000000..9ddcdd585d
--- /dev/null
+++ b/.github/workflows/test_t8code_macos.yml
@@ -0,0 +1,168 @@
+name: CMake tests t8code on Mac OS
+
+
+#  This file is part of t8code.
+#  t8code is a C library to manage a collection (a forest) of multiple
+#  connected adaptive space-trees of general element types in parallel.
+#
+#  Copyright (C) 2026 the developers
+#
+#  t8code is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  t8code is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with t8code; if not, write to the Free Software Foundation, Inc.,
+#  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+
+#  This workflow checks whether building and testing works on Mac OS. 
+#  In the past, this meant that Mac-OS-specific problems in t8code became
+#  apparrent only in Trixi and T8Code.jl, where they are very hard and
+#  cumbersome to debug. This workflow is intended to avoid that by catching
+#  such problems as early as possible, i.e., within t8code's CI.
+#  not just all of t8code's remaining CI workflows rely
+#  To reduce runtime, (for now) only one configuration is run, that is, Debug mode
+#  with MPI and all external libraries (VTK, OpenCASCADE).
+
+env:
+  DEBUG_CONFIG: "-O1"
+
+on:
+  workflow_call:
+    # Note: To simplify adding more configurations of this workflow later, the MPI mode and the BUILD_TYPE
+    #       are passed as input, although currently only MPI on and Debug mode are tested.
+    inputs:
+      MAKEFLAGS:
+        required: true
+        type: string
+        description: 'Make flags to use for compilation (like -j4)'
+      MPI:
+        required: true
+        type: string
+        description: 'Use MPI for compilation (ON/OFF)'
+      BUILD_TYPE:
+        required: true
+        type: string
+        description: 'Build type (Release/Debug)'
+      TEST_LEVEL:
+        required: true
+        type: string
+        description: 'Test level used for configuring (T8_TEST_LEVEL_FULL, T8_TEST_LEVEL_MEDIUM, or T8_TEST_LEVEL_BASIC)'
+        default: 'T8_TEST_LEVEL_FULL'
+
+jobs:
+  t8code_cmake_tests:
+  #
+  # Container setup: To avoid unwanted side effects of gcc or mpich, an own Clang version of the
+  #                  t8-dependencies Docker image is used. Aside from some basic packages, it contains a manually built
+  #                  Clang version of OpenMPI.
+    timeout-minutes: 60
+    runs-on: macos-latest
+    steps:
+  #
+  # Part 1: Preparation and sanity checks
+  # -------------------------------------
+    - uses: actions/checkout@v6
+      with:
+        fetch-depth: 0
+    - name: First dummy command
+      run: echo "Hello from Mac OS!"
+  #   - name: Update packages
+  #     run: apt-get update && apt-get upgrade -y
+    - name: Show Clang version
+      run: clang --version
+  #   - name: Make sure MPI was built with CLANG
+  #     # Note: If "clang" is not found (or "gcc" is), the workflow is exited due to fail-early mode
+  #     run: |
+  #       mpicc --version > mpi_version_output
+  #       cat mpi_version_output
+  #       grep -i "clang" mpi_version_output
+  #       ! grep -i "gcc" mpi_version_output
+  #       rm mpi_version_output
+  #       echo "CHECKED: MPI was built with Clang."
+  #   - name: Assert correct MPI paths
+  #     run: |
+  #       mpicc --showme:compile  | grep "${OMPI_INSTALL_PATH}"
+  #       mpicc --showme:link     | grep "${OMPI_INSTALL_PATH}"
+  #       mpicxx --showme:compile | grep "${OMPI_INSTALL_PATH}"
+  #       mpicxx --showme:link    | grep "${OMPI_INSTALL_PATH}"
+  #       echo "CHECKED: mpicc and mpicxx point to correct path"
+  #     # This seems to be necessary because of the docker container
+  #   - name: disable ownership checks
+  #     run: git config --global --add safe.directory '*'
+  #   - name: init submodules
+  #     run: git submodule init
+  #   - name: update submodules
+  #     run: git submodule update
+  #   - name: Get input vars
+  #     run: export MAKEFLAGS="${{ inputs.MAKEFLAGS }}"
+  #       && export MPI="${{ inputs.MPI }}"
+  #       && export BUILD_TYPE="${{ inputs.BUILD_TYPE }}"
+  #       && echo MAKEFLAGS="$MAKEFLAGS" >> $GITHUB_ENV
+  #       && echo MPI="$MPI" >> $GITHUB_ENV
+  #       && echo BUILD_TYPE="$BUILD_TYPE" >> $GITHUB_ENV
+  # #
+  # # Part 2: Build t8code
+  # # --------------------
+  #   # Define build config
+  #   - name: Set test level
+  #     run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
+  #          && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
+  #   - name: build config variables
+  #     run: |
+  #       export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -DCMAKE_Fortran_COMPILER=mpifort -GNinja \
+  #                              -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
+  #                              -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=ON -DT8CODE_BUILD_WEXTRA=ON \
+  #                              -DT8CODE_BUILD_FORTRAN_INTERFACE=ON -DT8CODE_BUILD_MESH_HANDLE=ON \
+  #                              -DT8CODE_ENABLE_OCC=ON -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=$VTK_INSTALL_PATH/lib/cmake/vtk-9.1"
+  #       echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
+  #   # Run cmake
+  #   - name: echo cmake line
+  #     run: echo cmake ../ $CONFIG_OPTIONS
+  #   - name: cmake
+  #     run: mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
+  #   # On failure, upload logs
+  #   - name: OnFailUploadLog
+  #     if: failure()
+  #     uses: actions/upload-artifact@v7
+  #     with:
+  #       name: cmake_w_clang_and_ompi_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+  #       path: build/CMakeFiles/CMakeOutput.log
+  #   # Build with ninja
+  #   - name: ninja
+  #     run: cd build && ninja $MAKEFLAGS
+  #   - name: ninja install
+  #     run: cd build && ninja install $MAKEFLAGS
+  # #
+  # # Part 3: Run t8code tests
+  # # ------------------------
+  #   - name: serial tests (if MPI is enabled)
+  #     run: cd build && ctest $MAKEFLAGS -R _serial
+  #     if: ${{ inputs.MPI == 'ON' }}
+  #   - name: parallel tests (if MPI is enabled)
+  #     run: cd build && ctest -R _parallel
+  #     env:
+  #       # Note: These openmpi options are required to ensure stable runs in github workflows and avoid stalling.
+  #       #       In particular, they activate oversubscription and define the communication channels, here tcp (and self).
+  #       OMPI_ALLOW_RUN_AS_ROOT: 1
+  #       OMPI_ALLOW_RUN_AS_ROOT_CONFIRM: 1
+  #       OMPI_MCA_rmaps_base_oversubscribe: 1
+  #       OMPI_MCA_btl: self,tcp
+  #       OMPI_MCA_pml: ob1
+  #     if: ${{ inputs.MPI == 'ON' }}
+  #   - name: tests (if MPI is disabled)
+  #     run: cd build && ctest $MAKEFLAGS
+  #     if: ${{ inputs.MPI == 'OFF' }}
+  #   # On failure, upload logs
+  #   - name: OnFailUploadLog
+  #     if: failure()
+  #     uses: actions/upload-artifact@v7
+  #     with:
+  #       name: test-suite_w_clang_and_ompi_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+  #       path: build/Testing/Temporary/LastTest.log
diff --git a/.github/workflows/testsuite.yml b/.github/workflows/testsuite.yml
index 631f7f48e8..b29908a481 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -242,6 +242,29 @@ jobs:
       BUILD_TYPE: ${{ matrix.BUILD_TYPE }}
       TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
 
+  # Check t8code building and testing with the Clang compiler and openmpi.
+  # Note: This workflow is meant to detect Clang- or openmpi-specific issues missed by the remaining (gcc- and mpich-based) workflows.
+  #       To reduce its runtime, it currently only uses one run in Debug mode with MPI activated and all external libraries like VTK or OpenCASCADE.
+  t8code_macos_tests:
+    needs: fine_grained_trigger
+    secrets: inherit
+    if: ${{ needs.fine_grained_trigger.outputs.run_ci == 'true' }}
+    uses: ./.github/workflows/test_t8code_macos.yml
+    strategy:
+      fail-fast: false
+      matrix:
+        MPI: [ON]
+        BUILD_TYPE: [Debug]
+        include:
+          - MAKEFLAGS: -j4
+    with:
+      MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
+      MPI: ${{ matrix.MPI }}
+      BUILD_TYPE: ${{ matrix.BUILD_TYPE }}
+      TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
+
+
+
   # Build doxygen documentation and check for errors / warnings.
   t8code_doxygen_check:
     uses: ./.github/workflows/check_doxygen.yml

From 3346b8492b409e5a27682dc57f1e88f75501e93e Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 30 Mar 2026 17:03:06 +0200
Subject: [PATCH 02/17] First tests [run ci]

---
 .github/workflows/test_t8code_macos.yml |  12 +-
 .github/workflows/testsuite.yml         | 238 ++++++++++++------------
 2 files changed, 125 insertions(+), 125 deletions(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index 9ddcdd585d..1552adef92 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -94,12 +94,12 @@ jobs:
   #       mpicxx --showme:link    | grep "${OMPI_INSTALL_PATH}"
   #       echo "CHECKED: mpicc and mpicxx point to correct path"
   #     # This seems to be necessary because of the docker container
-  #   - name: disable ownership checks
-  #     run: git config --global --add safe.directory '*'
-  #   - name: init submodules
-  #     run: git submodule init
-  #   - name: update submodules
-  #     run: git submodule update
+    - name: disable ownership checks
+      run: git config --global --add safe.directory '*'
+    - name: init submodules
+      run: git submodule init
+    - name: update submodules
+      run: git submodule update
   #   - name: Get input vars
   #     run: export MAKEFLAGS="${{ inputs.MAKEFLAGS }}"
   #       && export MPI="${{ inputs.MPI }}"
diff --git a/.github/workflows/testsuite.yml b/.github/workflows/testsuite.yml
index b29908a481..507ce524b1 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -123,124 +123,124 @@ jobs:
       CACHE_COUNTER: 0 # Increase this number to force a new installation of sc and p4est and to update the cache once
       MPI: ${{ matrix.MPI }}
 
-  # Run parallel tests for sc and p4est with and without MPI
-  sc_p4est_tests:
-    needs: preparation
-    uses: ./.github/workflows/test_sc_p4est.yml
-    strategy:
-      fail-fast: false
-      matrix:
-        MPI: [OFF, ON]
-        include:
-          - MAKEFLAGS: -j4
-    with:
-      MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
-      MPI: ${{ matrix.MPI }}
+  # # Run parallel tests for sc and p4est with and without MPI
+  # sc_p4est_tests:
+  #   needs: preparation
+  #   uses: ./.github/workflows/test_sc_p4est.yml
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       MPI: [OFF, ON]
+  #       include:
+  #         - MAKEFLAGS: -j4
+  #   with:
+  #     MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
+  #     MPI: ${{ matrix.MPI }}
 
-  # Run t8code tests with and without MPI and in serial and debug mode
-  t8code_tests:
-    needs: preparation
-    uses: ./.github/workflows/test_t8code.yml
-    strategy:
-      fail-fast: false
-      matrix:
-        MPI: [OFF, ON]
-        BUILD_TYPE: [Debug, Release]
-        include:
-          - MAKEFLAGS: -j4
-    with:
-      MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
-      MPI: ${{ matrix.MPI }}
-      BUILD_TYPE: ${{ matrix.BUILD_TYPE }}
-      TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
+  # # Run t8code tests with and without MPI and in serial and debug mode
+  # t8code_tests:
+  #   needs: preparation
+  #   uses: ./.github/workflows/test_t8code.yml
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       MPI: [OFF, ON]
+  #       BUILD_TYPE: [Debug, Release]
+  #       include:
+  #         - MAKEFLAGS: -j4
+  #   with:
+  #     MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
+  #     MPI: ${{ matrix.MPI }}
+  #     BUILD_TYPE: ${{ matrix.BUILD_TYPE }}
+  #     TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
 
-  # Run t8code linkage tests with and without MPI and in serial and debug mode
-  t8code_linkage_tests:
-    needs: preparation
-    uses: ./.github/workflows/test_t8code_linkage.yml
-    strategy:
-      fail-fast: false
-      matrix:
-        MPI: [OFF, ON]
-        BUILD_TYPE: [Debug, Release]
-        include:
-          - MAKEFLAGS: -j4
-    with:
-      MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
-      MPI: ${{ matrix.MPI }}
-      BUILD_TYPE: ${{ matrix.BUILD_TYPE }}
-      TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
+  # # Run t8code linkage tests with and without MPI and in serial and debug mode
+  # t8code_linkage_tests:
+  #   needs: preparation
+  #   uses: ./.github/workflows/test_t8code_linkage.yml
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       MPI: [OFF, ON]
+  #       BUILD_TYPE: [Debug, Release]
+  #       include:
+  #         - MAKEFLAGS: -j4
+  #   with:
+  #     MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
+  #     MPI: ${{ matrix.MPI }}
+  #     BUILD_TYPE: ${{ matrix.BUILD_TYPE }}
+  #     TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
 
-  # Run t8code linkage tests with and without MPI and in serial and debug mode
-  t8code_api_tests:
-    needs: preparation
-    uses: ./.github/workflows/test_t8code_api.yml
-    strategy:
-      fail-fast: false
-      matrix:
-        MPI: [ON] # For now the fortran API only supports building with MPI
-        BUILD_TYPE: [Debug, Release]
-        include:
-          - MAKEFLAGS: -j4
-    with:
-      MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
-      MPI: ${{ matrix.MPI }}
-      BUILD_TYPE: ${{ matrix.BUILD_TYPE }}
-      TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
+  # # Run t8code linkage tests with and without MPI and in serial and debug mode
+  # t8code_api_tests:
+  #   needs: preparation
+  #   uses: ./.github/workflows/test_t8code_api.yml
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       MPI: [ON] # For now the fortran API only supports building with MPI
+  #       BUILD_TYPE: [Debug, Release]
+  #       include:
+  #         - MAKEFLAGS: -j4
+  #   with:
+  #     MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
+  #     MPI: ${{ matrix.MPI }}
+  #     BUILD_TYPE: ${{ matrix.BUILD_TYPE }}
+  #     TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
 
-  # Run Valgrind check for every t8code test binary.
-  t8code_valgrind_tests:
-    if: (github.event_name == 'schedule' && github.repository == 'DLR-AMR/t8code') # Only run the Valgrind check in the scheduled run.
-    needs: preparation
-    uses: ./.github/workflows/test_valgrind.yml
-    with:
-      TEST_LEVEL: T8_TEST_LEVEL_BASIC # Do Valgrind check for test level T8_TEST_LEVEL_BASIC for performance reasons.
+  # # Run Valgrind check for every t8code test binary.
+  # t8code_valgrind_tests:
+  #   if: (github.event_name == 'schedule' && github.repository == 'DLR-AMR/t8code') # Only run the Valgrind check in the scheduled run.
+  #   needs: preparation
+  #   uses: ./.github/workflows/test_valgrind.yml
+  #   with:
+  #     TEST_LEVEL: T8_TEST_LEVEL_BASIC # Do Valgrind check for test level T8_TEST_LEVEL_BASIC for performance reasons.
 
-  # Generate code coverage and deploy to Codecov.
-  t8code_code_coverage:
-    if: (github.event_name != 'merge_group')
-    needs: preparation
-    uses: ./.github/workflows/code_coverage.yml
-    with:
-      MAKEFLAGS: -j4
-      MPI: ON
-      BUILD_TYPE: Debug
-      TEST_LEVEL: T8_TEST_LEVEL_BASIC
-    secrets:
-      CODE_COV: ${{ secrets.CODE_COV }}
+  # # Generate code coverage and deploy to Codecov.
+  # t8code_code_coverage:
+  #   if: (github.event_name != 'merge_group')
+  #   needs: preparation
+  #   uses: ./.github/workflows/code_coverage.yml
+  #   with:
+  #     MAKEFLAGS: -j4
+  #     MPI: ON
+  #     BUILD_TYPE: Debug
+  #     TEST_LEVEL: T8_TEST_LEVEL_BASIC
+  #   secrets:
+  #     CODE_COV: ${{ secrets.CODE_COV }}
 
-  # Run t8code tests with shipped submodules. This test is only for the build system, so only one config is tested.
-  t8code_w_shipped_submodules_tests:
-    needs: fine_grained_trigger
-    secrets: inherit
-    if: ${{ needs.fine_grained_trigger.outputs.run_ci == 'true' }}
-    uses: ./.github/workflows/test_t8code_w_shipped_submodules.yml
-    with:
-      MAKEFLAGS: -j4
-      MPI: ON
-      BUILD_TYPE: Debug
-      TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
+  # # Run t8code tests with shipped submodules. This test is only for the build system, so only one config is tested.
+  # t8code_w_shipped_submodules_tests:
+  #   needs: fine_grained_trigger
+  #   secrets: inherit
+  #   if: ${{ needs.fine_grained_trigger.outputs.run_ci == 'true' }}
+  #   uses: ./.github/workflows/test_t8code_w_shipped_submodules.yml
+  #   with:
+  #     MAKEFLAGS: -j4
+  #     MPI: ON
+  #     BUILD_TYPE: Debug
+  #     TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
 
-  # Check t8code building and testing with the Clang compiler and openmpi.
-  # Note: This workflow is meant to detect Clang- or openmpi-specific issues missed by the remaining (gcc- and mpich-based) workflows.
-  #       To reduce its runtime, it currently only uses one run in Debug mode with MPI activated and all external libraries like VTK or OpenCASCADE.
-  t8code_w_clang_and_ompi_tests:
-    needs: fine_grained_trigger
-    secrets: inherit
-    if: ${{ needs.fine_grained_trigger.outputs.run_ci == 'true' }}
-    uses: ./.github/workflows/test_t8code_w_clang_and_ompi.yml
-    strategy:
-      fail-fast: false
-      matrix:
-        MPI: [ON]
-        BUILD_TYPE: [Debug]
-        include:
-          - MAKEFLAGS: -j4
-    with:
-      MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
-      MPI: ${{ matrix.MPI }}
-      BUILD_TYPE: ${{ matrix.BUILD_TYPE }}
-      TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
+  # # Check t8code building and testing with the Clang compiler and openmpi.
+  # # Note: This workflow is meant to detect Clang- or openmpi-specific issues missed by the remaining (gcc- and mpich-based) workflows.
+  # #       To reduce its runtime, it currently only uses one run in Debug mode with MPI activated and all external libraries like VTK or OpenCASCADE.
+  # t8code_w_clang_and_ompi_tests:
+  #   needs: fine_grained_trigger
+  #   secrets: inherit
+  #   if: ${{ needs.fine_grained_trigger.outputs.run_ci == 'true' }}
+  #   uses: ./.github/workflows/test_t8code_w_clang_and_ompi.yml
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       MPI: [ON]
+  #       BUILD_TYPE: [Debug]
+  #       include:
+  #         - MAKEFLAGS: -j4
+  #   with:
+  #     MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
+  #     MPI: ${{ matrix.MPI }}
+  #     BUILD_TYPE: ${{ matrix.BUILD_TYPE }}
+  #     TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
 
   # Check t8code building and testing with the Clang compiler and openmpi.
   # Note: This workflow is meant to detect Clang- or openmpi-specific issues missed by the remaining (gcc- and mpich-based) workflows.
@@ -265,12 +265,12 @@ jobs:
 
 
 
-  # Build doxygen documentation and check for errors / warnings.
-  t8code_doxygen_check:
-    uses: ./.github/workflows/check_doxygen.yml
+  # # Build doxygen documentation and check for errors / warnings.
+  # t8code_doxygen_check:
+  #   uses: ./.github/workflows/check_doxygen.yml
 
-  t8code_tarball:
-    if: github.event.pull_request.draft == false
-    uses: ./.github/workflows/test_tarball.yml
-    with:
-      TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
+  # t8code_tarball:
+  #   if: github.event.pull_request.draft == false
+  #   uses: ./.github/workflows/test_tarball.yml
+  #   with:
+  #     TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_MEDIUM' || 'T8_TEST_LEVEL_FULL' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.

From c35e5f7870cc3d892f0990bc3aae32f3b5f70c04 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 30 Mar 2026 17:06:19 +0200
Subject: [PATCH 03/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 32 ++++++++++++-------------
 .github/workflows/testsuite.yml         | 32 ++++++++++++-------------
 2 files changed, 32 insertions(+), 32 deletions(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index 1552adef92..870e79cca1 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -71,12 +71,12 @@ jobs:
     - uses: actions/checkout@v6
       with:
         fetch-depth: 0
-    - name: First dummy command
-      run: echo "Hello from Mac OS!"
   #   - name: Update packages
   #     run: apt-get update && apt-get upgrade -y
     - name: Show Clang version
       run: clang --version
+    - name: Show mpicc version
+      run: mpicc --version
   #   - name: Make sure MPI was built with CLANG
   #     # Note: If "clang" is not found (or "gcc" is), the workflow is exited due to fail-early mode
   #     run: |
@@ -100,20 +100,20 @@ jobs:
       run: git submodule init
     - name: update submodules
       run: git submodule update
-  #   - name: Get input vars
-  #     run: export MAKEFLAGS="${{ inputs.MAKEFLAGS }}"
-  #       && export MPI="${{ inputs.MPI }}"
-  #       && export BUILD_TYPE="${{ inputs.BUILD_TYPE }}"
-  #       && echo MAKEFLAGS="$MAKEFLAGS" >> $GITHUB_ENV
-  #       && echo MPI="$MPI" >> $GITHUB_ENV
-  #       && echo BUILD_TYPE="$BUILD_TYPE" >> $GITHUB_ENV
-  # #
-  # # Part 2: Build t8code
-  # # --------------------
-  #   # Define build config
-  #   - name: Set test level
-  #     run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
-  #          && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
+    - name: Get input vars
+      run: export MAKEFLAGS="${{ inputs.MAKEFLAGS }}"
+        && export MPI="${{ inputs.MPI }}"
+        && export BUILD_TYPE="${{ inputs.BUILD_TYPE }}"
+        && echo MAKEFLAGS="$MAKEFLAGS" >> $GITHUB_ENV
+        && echo MPI="$MPI" >> $GITHUB_ENV
+        && echo BUILD_TYPE="$BUILD_TYPE" >> $GITHUB_ENV
+  #
+  # Part 2: Build t8code
+  # --------------------
+    # Define build config
+    - name: Set test level
+      run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
+           && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
   #   - name: build config variables
   #     run: |
   #       export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -DCMAKE_Fortran_COMPILER=mpifort -GNinja \
diff --git a/.github/workflows/testsuite.yml b/.github/workflows/testsuite.yml
index 507ce524b1..a054020008 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -106,22 +106,22 @@ jobs:
         fi
 
   # Preparation step for tests. Repo is cloned and sc + p4est are compiled with and without MPI.
-  preparation:
-    needs: [fine_grained_trigger]
-    secrets: inherit
-    if: needs.fine_grained_trigger.outputs.run_ci == 'true'
-    uses: ./.github/workflows/test_preparation.yml
-    strategy:
-      fail-fast: false
-      matrix:
-        MPI: [OFF, ON]
-        include:
-          - MAKEFLAGS: -j4
-    with:
-      MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
-      IGNORE_CACHE: false # Use this to force a new installation of sc and p4est for this specific workflow run
-      CACHE_COUNTER: 0 # Increase this number to force a new installation of sc and p4est and to update the cache once
-      MPI: ${{ matrix.MPI }}
+  # preparation:
+  #   needs: [fine_grained_trigger]
+  #   secrets: inherit
+  #   if: needs.fine_grained_trigger.outputs.run_ci == 'true'
+  #   uses: ./.github/workflows/test_preparation.yml
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       MPI: [OFF, ON]
+  #       include:
+  #         - MAKEFLAGS: -j4
+  #   with:
+  #     MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
+  #     IGNORE_CACHE: false # Use this to force a new installation of sc and p4est for this specific workflow run
+  #     CACHE_COUNTER: 0 # Increase this number to force a new installation of sc and p4est and to update the cache once
+  #     MPI: ${{ matrix.MPI }}
 
   # # Run parallel tests for sc and p4est with and without MPI
   # sc_p4est_tests:

From 9e2ab80edcf9df1f6bad6fbf00b4f60b124d8408 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 30 Mar 2026 17:08:35 +0200
Subject: [PATCH 04/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index 870e79cca1..af242f7140 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -75,6 +75,8 @@ jobs:
   #     run: apt-get update && apt-get upgrade -y
     - name: Show Clang version
       run: clang --version
+    - name: Debug via SSH
+      uses: mxschmitt/action-tmate@v3
     - name: Show mpicc version
       run: mpicc --version
   #   - name: Make sure MPI was built with CLANG

From 06804de2f71cff12edbb4ad555fa05a225a4f6f3 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 30 Mar 2026 17:11:06 +0200
Subject: [PATCH 05/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index af242f7140..aeda7009fc 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -71,8 +71,10 @@ jobs:
     - uses: actions/checkout@v6
       with:
         fetch-depth: 0
-  #   - name: Update packages
-  #     run: apt-get update && apt-get upgrade -y
+    - name: Update packages
+      run: brew update
+    - name: Install OpenMPI
+      run: brew install open-mpi
     - name: Show Clang version
       run: clang --version
     - name: Debug via SSH

From bbe9221e5960bb8343bf8a59e2d2bbf6b1228d34 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 30 Mar 2026 17:13:13 +0200
Subject: [PATCH 06/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 2 --
 1 file changed, 2 deletions(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index aeda7009fc..f33b2dfecc 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -77,8 +77,6 @@ jobs:
       run: brew install open-mpi
     - name: Show Clang version
       run: clang --version
-    - name: Debug via SSH
-      uses: mxschmitt/action-tmate@v3
     - name: Show mpicc version
       run: mpicc --version
   #   - name: Make sure MPI was built with CLANG

From 0ff629fa69c4f16c88ca1fa81bb511efabee0cf5 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 30 Mar 2026 17:21:19 +0200
Subject: [PATCH 07/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 132 +++++++++++-------------
 1 file changed, 58 insertions(+), 74 deletions(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index f33b2dfecc..94022c6d43 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -66,38 +66,22 @@ jobs:
     runs-on: macos-latest
     steps:
   #
-  # Part 1: Preparation and sanity checks
+  # Part 1: Preparation
   # -------------------------------------
     - uses: actions/checkout@v6
       with:
         fetch-depth: 0
     - name: Update packages
       run: brew update
-    - name: Install OpenMPI
-      run: brew install open-mpi
+    - name: Install missing packages via Homebrew
+      run: brew install open-mpi ninja cmake
     - name: Show Clang version
       run: clang --version
     - name: Show mpicc version
       run: mpicc --version
-  #   - name: Make sure MPI was built with CLANG
-  #     # Note: If "clang" is not found (or "gcc" is), the workflow is exited due to fail-early mode
-  #     run: |
-  #       mpicc --version > mpi_version_output
-  #       cat mpi_version_output
-  #       grep -i "clang" mpi_version_output
-  #       ! grep -i "gcc" mpi_version_output
-  #       rm mpi_version_output
-  #       echo "CHECKED: MPI was built with Clang."
-  #   - name: Assert correct MPI paths
-  #     run: |
-  #       mpicc --showme:compile  | grep "${OMPI_INSTALL_PATH}"
-  #       mpicc --showme:link     | grep "${OMPI_INSTALL_PATH}"
-  #       mpicxx --showme:compile | grep "${OMPI_INSTALL_PATH}"
-  #       mpicxx --showme:link    | grep "${OMPI_INSTALL_PATH}"
-  #       echo "CHECKED: mpicc and mpicxx point to correct path"
-  #     # This seems to be necessary because of the docker container
-    - name: disable ownership checks
-      run: git config --global --add safe.directory '*'
+
+    # - name: disable ownership checks
+    #   run: git config --global --add safe.directory '*'
     - name: init submodules
       run: git submodule init
     - name: update submodules
@@ -116,55 +100,55 @@ jobs:
     - name: Set test level
       run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
-  #   - name: build config variables
-  #     run: |
-  #       export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -DCMAKE_Fortran_COMPILER=mpifort -GNinja \
-  #                              -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
-  #                              -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=ON -DT8CODE_BUILD_WEXTRA=ON \
-  #                              -DT8CODE_BUILD_FORTRAN_INTERFACE=ON -DT8CODE_BUILD_MESH_HANDLE=ON \
-  #                              -DT8CODE_ENABLE_OCC=ON -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=$VTK_INSTALL_PATH/lib/cmake/vtk-9.1"
-  #       echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
-  #   # Run cmake
-  #   - name: echo cmake line
-  #     run: echo cmake ../ $CONFIG_OPTIONS
-  #   - name: cmake
-  #     run: mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
-  #   # On failure, upload logs
-  #   - name: OnFailUploadLog
-  #     if: failure()
-  #     uses: actions/upload-artifact@v7
-  #     with:
-  #       name: cmake_w_clang_and_ompi_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
-  #       path: build/CMakeFiles/CMakeOutput.log
-  #   # Build with ninja
-  #   - name: ninja
-  #     run: cd build && ninja $MAKEFLAGS
-  #   - name: ninja install
-  #     run: cd build && ninja install $MAKEFLAGS
-  # #
-  # # Part 3: Run t8code tests
-  # # ------------------------
-  #   - name: serial tests (if MPI is enabled)
-  #     run: cd build && ctest $MAKEFLAGS -R _serial
-  #     if: ${{ inputs.MPI == 'ON' }}
-  #   - name: parallel tests (if MPI is enabled)
-  #     run: cd build && ctest -R _parallel
-  #     env:
-  #       # Note: These openmpi options are required to ensure stable runs in github workflows and avoid stalling.
-  #       #       In particular, they activate oversubscription and define the communication channels, here tcp (and self).
-  #       OMPI_ALLOW_RUN_AS_ROOT: 1
-  #       OMPI_ALLOW_RUN_AS_ROOT_CONFIRM: 1
-  #       OMPI_MCA_rmaps_base_oversubscribe: 1
-  #       OMPI_MCA_btl: self,tcp
-  #       OMPI_MCA_pml: ob1
-  #     if: ${{ inputs.MPI == 'ON' }}
-  #   - name: tests (if MPI is disabled)
-  #     run: cd build && ctest $MAKEFLAGS
-  #     if: ${{ inputs.MPI == 'OFF' }}
-  #   # On failure, upload logs
-  #   - name: OnFailUploadLog
-  #     if: failure()
-  #     uses: actions/upload-artifact@v7
-  #     with:
-  #       name: test-suite_w_clang_and_ompi_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
-  #       path: build/Testing/Temporary/LastTest.log
+    - name: build config variables
+      run: |
+        export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -DCMAKE_Fortran_COMPILER=mpifort -GNinja \
+                               -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
+                               -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=ON -DT8CODE_BUILD_WEXTRA=ON \
+                               -DT8CODE_BUILD_FORTRAN_INTERFACE=ON -DT8CODE_BUILD_MESH_HANDLE=ON \
+                               -DT8CODE_ENABLE_OCC=ON -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=$VTK_INSTALL_PATH/lib/cmake/vtk-9.1"
+        echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
+    # Run cmake
+    - name: echo cmake line
+      run: echo cmake ../ $CONFIG_OPTIONS
+    - name: cmake
+      run: mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
+    # On failure, upload logs
+    - name: OnFailUploadLog
+      if: failure()
+      uses: actions/upload-artifact@v7
+      with:
+        name: cmake_w_clang_and_ompi_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+        path: build/CMakeFiles/CMakeOutput.log
+    # Build with ninja
+    - name: ninja
+      run: cd build && ninja $MAKEFLAGS
+    - name: ninja install
+      run: cd build && ninja install $MAKEFLAGS
+  #
+  # Part 3: Run t8code tests
+  # ------------------------
+    - name: serial tests (if MPI is enabled)
+      run: cd build && ctest $MAKEFLAGS -R _serial
+      if: ${{ inputs.MPI == 'ON' }}
+    - name: parallel tests (if MPI is enabled)
+      run: cd build && ctest -R _parallel
+      env:
+        # Note: These openmpi options are required to ensure stable runs in github workflows and avoid stalling.
+        #       In particular, they activate oversubscription and define the communication channels, here tcp (and self).
+        OMPI_ALLOW_RUN_AS_ROOT: 1
+        OMPI_ALLOW_RUN_AS_ROOT_CONFIRM: 1
+        OMPI_MCA_rmaps_base_oversubscribe: 1
+        OMPI_MCA_btl: self,tcp
+        OMPI_MCA_pml: ob1
+      if: ${{ inputs.MPI == 'ON' }}
+    - name: tests (if MPI is disabled)
+      run: cd build && ctest $MAKEFLAGS
+      if: ${{ inputs.MPI == 'OFF' }}
+    # On failure, upload logs
+    - name: OnFailUploadLog
+      if: failure()
+      uses: actions/upload-artifact@v7
+      with:
+        name: test-suite_w_clang_and_ompi_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+        path: build/Testing/Temporary/LastTest.log

From 580b68dc2f5160132349fa5d99df855c19ddefe5 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 30 Mar 2026 17:26:27 +0200
Subject: [PATCH 08/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index 94022c6d43..609dcded98 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -74,7 +74,7 @@ jobs:
     - name: Update packages
       run: brew update
     - name: Install missing packages via Homebrew
-      run: brew install open-mpi ninja cmake
+      run: brew install open-mpi ninja cmake googletest openssl
     - name: Show Clang version
       run: clang --version
     - name: Show mpicc version
@@ -102,12 +102,20 @@ jobs:
            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
     - name: build config variables
       run: |
-        export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -DCMAKE_Fortran_COMPILER=mpifort -GNinja \
+        export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -GNinja \
                                -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
                                -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=ON -DT8CODE_BUILD_WEXTRA=ON \
-                               -DT8CODE_BUILD_FORTRAN_INTERFACE=ON -DT8CODE_BUILD_MESH_HANDLE=ON \
-                               -DT8CODE_ENABLE_OCC=ON -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=$VTK_INSTALL_PATH/lib/cmake/vtk-9.1"
+                               -DT8CODE_BUILD_FORTRAN_INTERFACE=OFF -DT8CODE_BUILD_MESH_HANDLE=ON \
+                               -DT8CODE_ENABLE_OCC=ONFF -DT8CODE_ENABLE_VTK=OFF"
         echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
+    # - name: build config variables
+    # run: |
+    #   export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -DCMAKE_Fortran_COMPILER=mpifort -GNinja \
+    #                          -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
+    #                          -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=ON -DT8CODE_BUILD_WEXTRA=ON \
+    #                          -DT8CODE_BUILD_FORTRAN_INTERFACE=ON -DT8CODE_BUILD_MESH_HANDLE=ON \
+    #                          -DT8CODE_ENABLE_OCC=ON -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=$VTK_INSTALL_PATH/lib/cmake/vtk-9.1"
+    #   echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # Run cmake
     - name: echo cmake line
       run: echo cmake ../ $CONFIG_OPTIONS

From e922dd2815aeb270d6bda5d6f5f1317aea683746 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 30 Mar 2026 17:28:16 +0200
Subject: [PATCH 09/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index 609dcded98..587578faa3 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -106,7 +106,7 @@ jobs:
                                -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
                                -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=ON -DT8CODE_BUILD_WEXTRA=ON \
                                -DT8CODE_BUILD_FORTRAN_INTERFACE=OFF -DT8CODE_BUILD_MESH_HANDLE=ON \
-                               -DT8CODE_ENABLE_OCC=ONFF -DT8CODE_ENABLE_VTK=OFF"
+                               -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_VTK=OFF"
         echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # - name: build config variables
     # run: |

From ebca3b76ee240552d6c94aa63a735614da370a94 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 30 Mar 2026 17:30:42 +0200
Subject: [PATCH 10/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index 587578faa3..4be027f5c2 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -104,7 +104,7 @@ jobs:
       run: |
         export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -GNinja \
                                -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
-                               -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=ON -DT8CODE_BUILD_WEXTRA=ON \
+                               -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON \
                                -DT8CODE_BUILD_FORTRAN_INTERFACE=OFF -DT8CODE_BUILD_MESH_HANDLE=ON \
                                -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_VTK=OFF"
         echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV

From 53dafab3e701c79252d8157a5c8bba01db7103f7 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 30 Mar 2026 17:41:16 +0200
Subject: [PATCH 11/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index 4be027f5c2..a8a3be8236 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -102,7 +102,7 @@ jobs:
            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
     - name: build config variables
       run: |
-        export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -GNinja \
+        export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -GNinja -DCMAKE_INSTALL_PREFIX=$(pwd)/install \
                                -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
                                -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON \
                                -DT8CODE_BUILD_FORTRAN_INTERFACE=OFF -DT8CODE_BUILD_MESH_HANDLE=ON \

From db6aef0e428c7766c25118d250d377ed1ac6d18d Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 31 Mar 2026 09:27:12 +0200
Subject: [PATCH 12/17] Try only parallel tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index a8a3be8236..347fb6432a 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -136,9 +136,9 @@ jobs:
   #
   # Part 3: Run t8code tests
   # ------------------------
-    - name: serial tests (if MPI is enabled)
-      run: cd build && ctest $MAKEFLAGS -R _serial
-      if: ${{ inputs.MPI == 'ON' }}
+    # - name: serial tests (if MPI is enabled)
+    #   run: cd build && ctest $MAKEFLAGS -R _serial
+    #   if: ${{ inputs.MPI == 'ON' }}
     - name: parallel tests (if MPI is enabled)
       run: cd build && ctest -R _parallel
       env:

From 121e61f4dac050dccbe3af45b2ff5793046d6edc Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 31 Mar 2026 12:22:01 +0200
Subject: [PATCH 13/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index 347fb6432a..b9cd8a544b 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -103,7 +103,8 @@ jobs:
     - name: build config variables
       run: |
         export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -GNinja -DCMAKE_INSTALL_PREFIX=$(pwd)/install \
-                               -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
+                               -DT8CODE_ENABLE_MPI=$MPI -DMPIEXEC_PREFLAGS=--oversubscribe -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} \
+                               -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
                                -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON \
                                -DT8CODE_BUILD_FORTRAN_INTERFACE=OFF -DT8CODE_BUILD_MESH_HANDLE=ON \
                                -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_VTK=OFF"
@@ -138,7 +139,7 @@ jobs:
   # ------------------------
     # - name: serial tests (if MPI is enabled)
     #   run: cd build && ctest $MAKEFLAGS -R _serial
-    #   if: ${{ inputs.MPI == 'ON' }}
+      if: ${{ inputs.MPI == 'ON' }}
     - name: parallel tests (if MPI is enabled)
       run: cd build && ctest -R _parallel
       env:

From a5a987e483ab132d3e27e8573503c49cf6161bbb Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 31 Mar 2026 12:35:52 +0200
Subject: [PATCH 14/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index b9cd8a544b..bf09b1fb65 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -107,7 +107,13 @@ jobs:
                                -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
                                -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON \
                                -DT8CODE_BUILD_FORTRAN_INTERFACE=OFF -DT8CODE_BUILD_MESH_HANDLE=ON \
-                               -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_VTK=OFF"
+                               -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_VTK=OFF" \
+                               -DCTEST_PARALLEL_LEVEL=4 \
+                               -DENV_OMPI_ALLOW_RUN_AS_ROOT=1 \
+                               -DENV_OMPI_ALLOW_RUN_AS_ROOT_CONFIRM=1 \
+                               -DENV_OMPI_MCA_btl=self,tcp \
+                               -DENV_OMPI_MCA_pml=ob1 \
+                               -DENV_OMPI_MCA_rmaps_base_oversubscribe=1
         echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # - name: build config variables
     # run: |

From d1ebefa0cd4d8583519b31b508a089ec74dd42cc Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 31 Mar 2026 12:44:25 +0200
Subject: [PATCH 15/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index bf09b1fb65..2c1c8b5d3b 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -107,13 +107,13 @@ jobs:
                                -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
                                -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON \
                                -DT8CODE_BUILD_FORTRAN_INTERFACE=OFF -DT8CODE_BUILD_MESH_HANDLE=ON \
-                               -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_VTK=OFF" \
+                               -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_VTK=OFF \
                                -DCTEST_PARALLEL_LEVEL=4 \
                                -DENV_OMPI_ALLOW_RUN_AS_ROOT=1 \
                                -DENV_OMPI_ALLOW_RUN_AS_ROOT_CONFIRM=1 \
                                -DENV_OMPI_MCA_btl=self,tcp \
                                -DENV_OMPI_MCA_pml=ob1 \
-                               -DENV_OMPI_MCA_rmaps_base_oversubscribe=1
+                               -DENV_OMPI_MCA_rmaps_base_oversubscribe=1"
         echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # - name: build config variables
     # run: |

From 6cdca1e3724db6c6dce78dc894d0d19065db8e82 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 31 Mar 2026 12:53:09 +0200
Subject: [PATCH 16/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index 2c1c8b5d3b..b54c8de82b 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -102,18 +102,11 @@ jobs:
            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
     - name: build config variables
       run: |
-        export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -GNinja -DCMAKE_INSTALL_PREFIX=$(pwd)/install \
-                               -DT8CODE_ENABLE_MPI=$MPI -DMPIEXEC_PREFLAGS=--oversubscribe -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} \
-                               -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
+        export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -GNinja \
+                               -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
                                -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON \
                                -DT8CODE_BUILD_FORTRAN_INTERFACE=OFF -DT8CODE_BUILD_MESH_HANDLE=ON \
-                               -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_VTK=OFF \
-                               -DCTEST_PARALLEL_LEVEL=4 \
-                               -DENV_OMPI_ALLOW_RUN_AS_ROOT=1 \
-                               -DENV_OMPI_ALLOW_RUN_AS_ROOT_CONFIRM=1 \
-                               -DENV_OMPI_MCA_btl=self,tcp \
-                               -DENV_OMPI_MCA_pml=ob1 \
-                               -DENV_OMPI_MCA_rmaps_base_oversubscribe=1"
+                               -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_VTK=OFF"
         echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # - name: build config variables
     # run: |
@@ -147,7 +140,13 @@ jobs:
     #   run: cd build && ctest $MAKEFLAGS -R _serial
       if: ${{ inputs.MPI == 'ON' }}
     - name: parallel tests (if MPI is enabled)
-      run: cd build && ctest -R _parallel
+      run: |
+        export OMPI_ALLOW_RUN_AS_ROOT=1
+        export OMPI_ALLOW_RUN_AS_ROOT_CONFIRM=1
+        export OMPI_MCA_btl=self,tcp
+        export OMPI_MCA_pml=ob1
+        export OMPI_MCA_rmaps_base_oversubscribe=1
+        cd build && ctest -R _parallel
       env:
         # Note: These openmpi options are required to ensure stable runs in github workflows and avoid stalling.
         #       In particular, they activate oversubscription and define the communication channels, here tcp (and self).

From 953c6d856d059d9726a354da8c803bcfba3f1baf Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 31 Mar 2026 13:08:59 +0200
Subject: [PATCH 17/17] More tests [run ci]

---
 .github/workflows/test_t8code_macos.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_macos.yml b/.github/workflows/test_t8code_macos.yml
index b54c8de82b..9a9693f4a7 100644
--- a/.github/workflows/test_t8code_macos.yml
+++ b/.github/workflows/test_t8code_macos.yml
@@ -102,7 +102,7 @@ jobs:
            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
     - name: build config variables
       run: |
-        export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -GNinja \
+        export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -GNinja -DCMAKE_INSTALL_PREFIX=$(pwd)/install \\
                                -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
                                -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON \
                                -DT8CODE_BUILD_FORTRAN_INTERFACE=OFF -DT8CODE_BUILD_MESH_HANDLE=ON \