From 12a4c7a9359e69948177bd4e6a25cd0cf41cc808 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 08:29:41 +0100
Subject: [PATCH 01/99] First test towards CLANG ci workflow

---
 .../tests_cmake_t8code_w_other_compilers.yml  | 126 ++++++++++++
 .github/workflows/tests_cmake_testsuite.yml   | 181 ++++++++++--------
 2 files changed, 227 insertions(+), 80 deletions(-)
 create mode 100644 .github/workflows/tests_cmake_t8code_w_other_compilers.yml

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
new file mode 100644
index 0000000000..d480fc644c
--- /dev/null
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -0,0 +1,126 @@
+name: CMake tests t8code with shipped submodules
+
+
+#  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) 2024 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.
+
+env:
+  DEBUG_CONFIG: "-O1"
+
+on:
+  workflow_call:
+    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'
+      COMPILER:
+        required: true
+        type: string
+        description: 'Compiler (CLANG)'
+
+jobs:
+  t8code_cmake_tests:
+    timeout-minutes: 60
+    runs-on: ubuntu-latest
+    container: dlramr/t8code-ubuntu:t8-dependencies
+    steps:
+#
+# Setup
+#
+    - uses: actions/checkout@v6
+      with:
+        fetch-depth: 0
+    - name: Update packages
+      run: sudo apt-get update && sudo apt-get upgrade -y
+      # MYTODO: Somehow make github use CLANG here :-)
+    - name: Check clang version
+      run: clang --version
+      # 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" >> $GITHUB_ENV
+# #
+# #  T8CODE
+# #
+#     # build config vars
+#     - name: Set test level
+#       run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
+#            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
+#     - name: build config variables
+#       run: export CONFIG_OPTIONS="${TEST_LEVEL_FLAG} -GNinja -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_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
+#         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
+#     # cmake and test
+#     - name: Printing MPI compiler info
+#       run: mpicc --version && mpirun --version
+#     - name: Printing GCC compiler info
+#       run: gcc --version && g++ --version
+#     - name: echo cmake line
+#       run: echo cmake ../ $CONFIG_OPTIONS
+#     - name: cmake
+#       run: mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
+#     - name: OnFailUploadLog
+#       if: failure()
+#       uses: actions/upload-artifact@v5
+#       with:
+#         name: cmake_w_submodules_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+#         path: build/CMakeFiles/CMakeOutput.log
+#     - name: ninja
+#       run: cd build && ninja $MAKEFLAGS
+#     - name: ninja install
+#       run: cd build && ninja install $MAKEFLAGS
+#     - 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
+#       if: ${{ inputs.MPI == 'ON' }}
+#     - name: tests (if MPI is disabled)
+#       run: cd build && ctest $MAKEFLAGS
+#       if: ${{ inputs.MPI == 'OFF' }}
+#     - name: OnFailUploadLog
+#       if: failure()
+#       uses: actions/upload-artifact@v5
+#       with:
+#         name: test-suite_w_submodules_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+#         path: build/Testing/Temporary/LastTest.log
diff --git a/.github/workflows/tests_cmake_testsuite.yml b/.github/workflows/tests_cmake_testsuite.yml
index c1c9535700..feec707388 100644
--- a/.github/workflows/tests_cmake_testsuite.yml
+++ b/.github/workflows/tests_cmake_testsuite.yml
@@ -123,107 +123,128 @@ 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/tests_cmake_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/tests_cmake_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/tests_cmake_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/tests_cmake_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/tests_cmake_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/tests_cmake_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/tests_cmake_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/tests_cmake_valgrind.yml
+  #   with:
+  #     MAKEFLAGS: -j4
+  #     MPI: ON
+  #     BUILD_TYPE: Debug
+  #     TEST_LEVEL: T8_TEST_LEVEL_BASIC # Do Valgrind check for test level T8_TEST_LEVEL_BASIC for performance reasons.
 
-  # Run t8code linkage tests with and without MPI and in serial and debug mode
-  t8code_api_tests:
-    needs: preparation
-    uses: ./.github/workflows/tests_cmake_t8code_api.yml
+  # # 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_other_compilers_tests:
+    needs: fine_grained_trigger
+    secrets: inherit
+    if: ${{ needs.fine_grained_trigger.outputs.run_ci == 'true' }}
+    uses: ./.github/workflows/tests_cmake_t8code_w_shipped_submodules.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/tests_cmake_valgrind.yml
+      # matrix:
+      #   MPI: [OFF, ON]
+      #   BUILD_TYPE: [Debug, Release]
+      #   include: 
+      #     - MAKEFLAGS: -j4
     with:
       MAKEFLAGS: -j4
       MPI: ON
       BUILD_TYPE: Debug
-      TEST_LEVEL: T8_TEST_LEVEL_BASIC # Do Valgrind check for test level T8_TEST_LEVEL_BASIC for performance reasons.
+      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.
+      COMPILER: CLANG
 
-  # 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/tests_cmake_t8code_w_shipped_submodules.yml
+    uses: ./.github/workflows/tests_cmake_t8code_w_other_compilers.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.
 
+
   t8code_doxygen_check:
     uses: ./.github/workflows/check_doxygen.yml
     needs: [preparation, sc_p4est_tests, t8code_tests, t8code_linkage_tests, t8code_api_tests, t8code_w_shipped_submodules_tests]

From 1ef437eb2890691b8e79191a2ea78d447c7f185e Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 08:34:45 +0100
Subject: [PATCH 02/99] Try again

---
 .github/workflows/tests_cmake_testsuite.yml | 38 ++++++++++-----------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/.github/workflows/tests_cmake_testsuite.yml b/.github/workflows/tests_cmake_testsuite.yml
index feec707388..6780c0a8f7 100644
--- a/.github/workflows/tests_cmake_testsuite.yml
+++ b/.github/workflows/tests_cmake_testsuite.yml
@@ -233,25 +233,25 @@ jobs:
       COMPILER: CLANG
 
   # 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/tests_cmake_t8code_w_other_compilers.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.
+  # t8code_w_shipped_submodules_tests:
+  #   needs: fine_grained_trigger
+  #   secrets: inherit
+  #   if: ${{ needs.fine_grained_trigger.outputs.run_ci == 'true' }}
+  #   uses: ./.github/workflows/tests_cmake_t8code_w_other_compilers.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.
 
 
-  t8code_doxygen_check:
-    uses: ./.github/workflows/check_doxygen.yml
-    needs: [preparation, sc_p4est_tests, t8code_tests, t8code_linkage_tests, t8code_api_tests, t8code_w_shipped_submodules_tests]
+  # t8code_doxygen_check:
+  #   uses: ./.github/workflows/check_doxygen.yml
+  #   needs: [preparation, sc_p4est_tests, t8code_tests, t8code_linkage_tests, t8code_api_tests, t8code_w_shipped_submodules_tests]
 
-  t8code_tarball:
-    if: github.event.pull_request.draft == false
-    uses: ./.github/workflows/build_cmake_tarball.yml
-    needs: [preparation, sc_p4est_tests, t8code_tests, t8code_linkage_tests, t8code_api_tests, t8code_w_shipped_submodules_tests]
-    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/build_cmake_tarball.yml
+  #   needs: [preparation, sc_p4est_tests, t8code_tests, t8code_linkage_tests, t8code_api_tests, t8code_w_shipped_submodules_tests]
+  #   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 d8dfa8056a53f1da12eece7f33356705a97d8cf5 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 08:38:12 +0100
Subject: [PATCH 03/99] Try again

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

diff --git a/.github/workflows/tests_cmake_testsuite.yml b/.github/workflows/tests_cmake_testsuite.yml
index 6780c0a8f7..ba893d2fba 100644
--- a/.github/workflows/tests_cmake_testsuite.yml
+++ b/.github/workflows/tests_cmake_testsuite.yml
@@ -217,7 +217,7 @@ jobs:
     needs: fine_grained_trigger
     secrets: inherit
     if: ${{ needs.fine_grained_trigger.outputs.run_ci == 'true' }}
-    uses: ./.github/workflows/tests_cmake_t8code_w_shipped_submodules.yml
+    uses: ./.github/workflows/tests_cmake_t8code_w_other_compilers.yml
     strategy:
       fail-fast: false
       # matrix:

From 1d12859fa33935bb28335d8d36bfd14d6c330a56 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 08:42:47 +0100
Subject: [PATCH 04/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_testsuite.yml | 22 ++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/.github/workflows/tests_cmake_testsuite.yml b/.github/workflows/tests_cmake_testsuite.yml
index ba893d2fba..c0a2f72304 100644
--- a/.github/workflows/tests_cmake_testsuite.yml
+++ b/.github/workflows/tests_cmake_testsuite.yml
@@ -51,8 +51,8 @@ concurrency:
 # - run on draft PRs, if the latest commit message contains '[run ci]'
 # - run on scheduled runs for the DLR-AMR/t8code repository
 # - run on all other pull request events
-# These conditions are checked in the fine_grained_trigger job. If it completes successfully, it triggers the preparation job, 
-# which triggers the actual tests. 
+# These conditions are checked in the fine_grained_trigger job. If it completes successfully, it triggers the preparation job,
+# which triggers the actual tests.
 # The job to build the tarball is only triggered on merge_group events for the DLR-AMR/t8code repository.
 
 jobs:
@@ -115,14 +115,14 @@ jobs:
       fail-fast: false
       matrix:
         MPI: [OFF, ON]
-        include: 
+        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:
   #   needs: preparation
@@ -131,7 +131,7 @@ jobs:
   #     fail-fast: false
   #     matrix:
   #       MPI: [OFF, ON]
-  #       include: 
+  #       include:
   #         - MAKEFLAGS: -j4
   #   with:
   #     MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
@@ -146,14 +146,14 @@ jobs:
   #     matrix:
   #       MPI: [OFF, ON]
   #       BUILD_TYPE: [Debug, Release]
-  #       include: 
+  #       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
@@ -163,7 +163,7 @@ jobs:
   #     matrix:
   #       MPI: [OFF, ON]
   #       BUILD_TYPE: [Debug, Release]
-  #       include: 
+  #       include:
   #         - MAKEFLAGS: -j4
   #   with:
   #     MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
@@ -180,7 +180,7 @@ jobs:
   #     matrix:
   #       MPI: [ON] # For now the fortran API only supports building with MPI
   #       BUILD_TYPE: [Debug, Release]
-  #       include: 
+  #       include:
   #         - MAKEFLAGS: -j4
   #   with:
   #     MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
@@ -211,7 +211,7 @@ jobs:
   #     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_other_compilers_tests:
     needs: fine_grained_trigger
@@ -223,7 +223,7 @@ jobs:
       # matrix:
       #   MPI: [OFF, ON]
       #   BUILD_TYPE: [Debug, Release]
-      #   include: 
+      #   include:
       #     - MAKEFLAGS: -j4
     with:
       MAKEFLAGS: -j4

From 5aebc56644a42da997ea7ea7d390c3a4dc252393 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 09:10:53 +0100
Subject: [PATCH 05/99] Trigger [run ci]

---
 .../tests_cmake_t8code_w_other_compilers.yml  |  4 +++
 .github/workflows/tests_cmake_testsuite.yml   | 32 +++++++++----------
 2 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index d480fc644c..0ff8423d94 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -63,9 +63,13 @@ jobs:
         fetch-depth: 0
     - name: Update packages
       run: sudo apt-get update && sudo apt-get upgrade -y
+    - name: Install CLANG
+      run: sudo apt install clang
       # MYTODO: Somehow make github use CLANG here :-)
     - name: Check clang version
       run: clang --version
+    - name: Show MPI version
+      run: which mpi
       # This seems to be necessary because of the docker container
 #     - name: disable ownership checks
 #       run: git config --global --add safe.directory '*'
diff --git a/.github/workflows/tests_cmake_testsuite.yml b/.github/workflows/tests_cmake_testsuite.yml
index c0a2f72304..3568f00d69 100644
--- a/.github/workflows/tests_cmake_testsuite.yml
+++ b/.github/workflows/tests_cmake_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/tests_cmake_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/tests_cmake_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 bb6d163b124ff727c43ce4995ca0d2884738756d Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 09:17:30 +0100
Subject: [PATCH 06/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 0ff8423d94..bbdf0f108c 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -64,7 +64,7 @@ jobs:
     - name: Update packages
       run: sudo apt-get update && sudo apt-get upgrade -y
     - name: Install CLANG
-      run: sudo apt install clang
+      run: sudo apt-get install clang -y
       # MYTODO: Somehow make github use CLANG here :-)
     - name: Check clang version
       run: clang --version

From 3c903b9f948b6c223e67902c39e295bd1c21e780 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 09:41:20 +0100
Subject: [PATCH 07/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index bbdf0f108c..f1d15e38bb 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -65,11 +65,10 @@ jobs:
       run: sudo apt-get update && sudo apt-get upgrade -y
     - name: Install CLANG
       run: sudo apt-get install clang -y
-      # MYTODO: Somehow make github use CLANG here :-)
     - name: Check clang version
       run: clang --version
     - name: Show MPI version
-      run: which mpi
+      run: which mpicc
       # This seems to be necessary because of the docker container
 #     - name: disable ownership checks
 #       run: git config --global --add safe.directory '*'

From d2c2c9afb8c742e9c543ba2919873b3ebb5ee422 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 09:51:36 +0100
Subject: [PATCH 08/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index f1d15e38bb..28493c4a99 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -67,8 +67,11 @@ jobs:
       run: sudo apt-get install clang -y
     - name: Check clang version
       run: clang --version
+    # - name: Install another MPI version
+    #   run: |
+    #     sudo apt install -y libopenmpi-dev openmpi-bin
     - name: Show MPI version
-      run: which mpicc
+      run: mpicc --version
       # This seems to be necessary because of the docker container
 #     - name: disable ownership checks
 #       run: git config --global --add safe.directory '*'

From e017db6bb14c6b8bad39a9a4de089d8613f40ccf Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 09:59:06 +0100
Subject: [PATCH 09/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 28493c4a99..e2523eabea 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -67,9 +67,9 @@ jobs:
       run: sudo apt-get install clang -y
     - name: Check clang version
       run: clang --version
-    # - name: Install another MPI version
-    #   run: |
-    #     sudo apt install -y libopenmpi-dev openmpi-bin
+    - name: Install another MPI version
+      run: |
+        sudo apt install -y libopenmpi-dev openmpi-bin
     - name: Show MPI version
       run: mpicc --version
       # This seems to be necessary because of the docker container

From 2c3e72320a31a7a34c460d7fbe30bb91b6607d38 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:03:09 +0100
Subject: [PATCH 10/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index e2523eabea..52ebaa2b31 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -67,11 +67,15 @@ jobs:
       run: sudo apt-get install clang -y
     - name: Check clang version
       run: clang --version
+    # - name: Set clang as compiler
     - name: Install another MPI version
       run: |
         sudo apt install -y libopenmpi-dev openmpi-bin
     - name: Show MPI version
-      run: mpicc --version
+      run: |
+        export CC=clang
+        export CXX=clang++
+        mpicc --version
       # This seems to be necessary because of the docker container
 #     - name: disable ownership checks
 #       run: git config --global --add safe.directory '*'

From 70c9fcef63648b0e7d95332bb1bb0806395c2842 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:12:23 +0100
Subject: [PATCH 11/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 52ebaa2b31..d6755c1b1b 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -1,4 +1,4 @@
-name: CMake tests t8code with shipped submodules
+name: CMake tests t8code with other compilers
 
 
 #  This file is part of t8code.
@@ -53,7 +53,7 @@ jobs:
   t8code_cmake_tests:
     timeout-minutes: 60
     runs-on: ubuntu-latest
-    container: dlramr/t8code-ubuntu:t8-dependencies
+    container: ubuntu:20.04
     steps:
 #
 # Setup

From 99017c371230923b2dd8c63a51684aa7c1a76c89 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:14:22 +0100
Subject: [PATCH 12/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index d6755c1b1b..9337fcc5c5 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -62,7 +62,9 @@ jobs:
       with:
         fetch-depth: 0
     - name: Update packages
-      run: sudo apt-get update && sudo apt-get upgrade -y
+      run: |
+        apt-get install -y sudo
+        sudo apt-get update && sudo apt-get upgrade -y
     - name: Install CLANG
       run: sudo apt-get install clang -y
     - name: Check clang version

From f1858348208f31719f69a303714fbd0357208995 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:16:08 +0100
Subject: [PATCH 13/99] Trigger [run ci]

---
 .../workflows/tests_cmake_t8code_w_other_compilers.yml    | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 9337fcc5c5..12dd89e9fc 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -62,17 +62,15 @@ jobs:
       with:
         fetch-depth: 0
     - name: Update packages
-      run: |
-        apt-get install -y sudo
-        sudo apt-get update && sudo apt-get upgrade -y
+      run: apt-get update && apt-get upgrade -y
     - name: Install CLANG
-      run: sudo apt-get install clang -y
+      run: apt-get install clang -y
     - name: Check clang version
       run: clang --version
     # - name: Set clang as compiler
     - name: Install another MPI version
       run: |
-        sudo apt install -y libopenmpi-dev openmpi-bin
+        apt install -y libopenmpi-dev openmpi-bin
     - name: Show MPI version
       run: |
         export CC=clang

From 14abfd88dd435d3ef166fd312624247b38443f15 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:18:15 +0100
Subject: [PATCH 14/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 12dd89e9fc..a0e77af582 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -53,7 +53,7 @@ jobs:
   t8code_cmake_tests:
     timeout-minutes: 60
     runs-on: ubuntu-latest
-    container: ubuntu:20.04
+    container: ubuntu:latest
     steps:
 #
 # Setup

From 44c369e1d76d2b3345135b7e7133a7af5dc3505a Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:21:10 +0100
Subject: [PATCH 15/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index a0e77af582..c056142554 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -53,7 +53,7 @@ jobs:
   t8code_cmake_tests:
     timeout-minutes: 60
     runs-on: ubuntu-latest
-    container: ubuntu:latest
+    container: ubuntu:22.04
     steps:
 #
 # Setup

From 461ceea6001e842fcb4c650a89c9eed1a85a5986 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:22:18 +0100
Subject: [PATCH 16/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index c056142554..57d3ba629d 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -67,6 +67,8 @@ jobs:
       run: apt-get install clang -y
     - name: Check clang version
       run: clang --version
+    - name: Check whether gcc is there
+      run: gcc --version      
     # - name: Set clang as compiler
     - name: Install another MPI version
       run: |

From 87da1e42d6e467ec16fa48289f76eb3069ef0432 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:25:18 +0100
Subject: [PATCH 17/99] Trigger [run ci]

---
 .../tests_cmake_t8code_w_other_compilers.yml         | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 57d3ba629d..79605ce75f 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -64,15 +64,15 @@ jobs:
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
     - name: Install CLANG
-      run: apt-get install clang -y
+      run: apt-get install -y clang  libopenmpi-dev openmpi-bin
     - name: Check clang version
       run: clang --version
-    - name: Check whether gcc is there
-      run: gcc --version      
+    # - name: Check whether gcc is there
+    #   run: gcc --version
     # - name: Set clang as compiler
-    - name: Install another MPI version
-      run: |
-        apt install -y libopenmpi-dev openmpi-bin
+    # - name: Install another MPI version
+    #   run: |
+    #     apt install -y libopenmpi-dev openmpi-bin
     - name: Show MPI version
       run: |
         export CC=clang

From 5a760051435b99e4b3acbe6a4cc45ac74833e63d Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:41:09 +0100
Subject: [PATCH 18/99] Trigger [run ci]

---
 .../workflows/tests_cmake_t8code_w_other_compilers.yml | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 79605ce75f..a07af1b458 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -62,17 +62,11 @@ jobs:
       with:
         fetch-depth: 0
     - name: Update packages
-      run: apt-get update && apt-get upgrade -y
+      run: sudo apt-get update && sudo apt-get upgrade -y
     - name: Install CLANG
-      run: apt-get install -y clang  libopenmpi-dev openmpi-bin
+      run: sudo apt-get install clang -y
     - name: Check clang version
       run: clang --version
-    # - name: Check whether gcc is there
-    #   run: gcc --version
-    # - name: Set clang as compiler
-    # - name: Install another MPI version
-    #   run: |
-    #     apt install -y libopenmpi-dev openmpi-bin
     - name: Show MPI version
       run: |
         export CC=clang

From 9305ce5654a658d3a6441083df1b60a195abed90 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:44:57 +0100
Subject: [PATCH 19/99] Trigger [run ci]

---
 .../tests_cmake_t8code_w_other_compilers.yml          | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index a07af1b458..3bd46af866 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -67,6 +67,17 @@ jobs:
       run: sudo apt-get install clang -y
     - name: Check clang version
       run: clang --version
+    - name: Install openmpi with CLANG
+      run: |
+      mkdir install_ompi_clang
+      wget https://download.open-mpi.org/release/open-mpi/v4.1/openmpi-4.1.6.tar.gz
+      tar xf openmpi-4.1.6.tar.gz
+      cd openmpi-4.1.6
+      CC=clang CXX=clang++ ./configure --prefix=../install_ompi_clang
+      make -j$(nproc)
+      make install
+      cd ..
+      export PATH=$(pwd)/install_ompi_clang/bin:$PATH
     - name: Show MPI version
       run: |
         export CC=clang

From d8a3d3b843130d4dfaf1ee9b43dd79cfee3f9288 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:46:23 +0100
Subject: [PATCH 20/99] Trigger [run ci]

---
 .../tests_cmake_t8code_w_other_compilers.yml  | 22 +++++++++----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 3bd46af866..699deb81ff 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -62,22 +62,22 @@ jobs:
       with:
         fetch-depth: 0
     - name: Update packages
-      run: sudo apt-get update && sudo apt-get upgrade -y
+      run: apt-get update && sudo apt-get upgrade -y
     - name: Install CLANG
-      run: sudo apt-get install clang -y
+      run: apt-get install clang -y
     - name: Check clang version
       run: clang --version
     - name: Install openmpi with CLANG
       run: |
-      mkdir install_ompi_clang
-      wget https://download.open-mpi.org/release/open-mpi/v4.1/openmpi-4.1.6.tar.gz
-      tar xf openmpi-4.1.6.tar.gz
-      cd openmpi-4.1.6
-      CC=clang CXX=clang++ ./configure --prefix=../install_ompi_clang
-      make -j$(nproc)
-      make install
-      cd ..
-      export PATH=$(pwd)/install_ompi_clang/bin:$PATH
+        mkdir install_ompi_clang
+        wget https://download.open-mpi.org/release/open-mpi/v4.1/openmpi-4.1.6.tar.gz
+        tar xf openmpi-4.1.6.tar.gz
+        cd openmpi-4.1.6
+        CC=clang CXX=clang++ ./configure --prefix=../install_ompi_clang
+        make -j$(nproc)
+        make install
+        cd ..
+        export PATH=$(pwd)/install_ompi_clang/bin:$PATH
     - name: Show MPI version
       run: |
         export CC=clang

From 12acf57e9190e222b6897d682d1dfc51ba69d3a9 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:48:06 +0100
Subject: [PATCH 21/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 699deb81ff..955b7f0bc2 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -62,7 +62,7 @@ jobs:
       with:
         fetch-depth: 0
     - name: Update packages
-      run: apt-get update && sudo apt-get upgrade -y
+      run: apt-get update && apt-get upgrade -y
     - name: Install CLANG
       run: apt-get install clang -y
     - name: Check clang version

From d2ca2d3e5e591ab736d4dd1b04925c290cdff18d Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:50:14 +0100
Subject: [PATCH 22/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 955b7f0bc2..625c855d05 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -63,6 +63,8 @@ jobs:
         fetch-depth: 0
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
+    - name: Install some basic packages
+      run: apt-get install -y wget tar
     - name: Install CLANG
       run: apt-get install clang -y
     - name: Check clang version

From a82a9f2b24d6df658bb79cb73273cba991bde796 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 10:53:13 +0100
Subject: [PATCH 23/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 625c855d05..1b25512208 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -72,14 +72,15 @@ jobs:
     - name: Install openmpi with CLANG
       run: |
         mkdir install_ompi_clang
+        export OMPI_INSTALL_PATH=$(pwd)/install_ompi_clang
         wget https://download.open-mpi.org/release/open-mpi/v4.1/openmpi-4.1.6.tar.gz
         tar xf openmpi-4.1.6.tar.gz
         cd openmpi-4.1.6
-        CC=clang CXX=clang++ ./configure --prefix=../install_ompi_clang
+        CC=clang CXX=clang++ ./configure --prefix=$OMPI_INSTALL_PATH
         make -j$(nproc)
         make install
         cd ..
-        export PATH=$(pwd)/install_ompi_clang/bin:$PATH
+        export PATH=$OMPI_INSTALL_PATH/bin:$PATH
     - name: Show MPI version
       run: |
         export CC=clang

From 4d853ac436edbb37129e479c5d1c6f00451284fc Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 11:02:22 +0100
Subject: [PATCH 24/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 1b25512208..edeccf1c72 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -64,7 +64,7 @@ jobs:
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
     - name: Install some basic packages
-      run: apt-get install -y wget tar
+      run: apt-get install -y wget tar lld make libc6-dev libc++-dev libc++abi-dev
     - name: Install CLANG
       run: apt-get install clang -y
     - name: Check clang version

From 58fde706b4c53c3acf1e2219d257c3c9125f697b Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 11:10:28 +0100
Subject: [PATCH 25/99] Trigger [run ci]

---
 .../tests_cmake_t8code_w_other_compilers.yml         | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index edeccf1c72..1140e46cd5 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -64,7 +64,14 @@ jobs:
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
     - name: Install some basic packages
-      run: apt-get install -y wget tar lld make libc6-dev libc++-dev libc++abi-dev
+      run: |
+        apt-get install -y wget tar lld make \
+          libc6-dev libc++-dev libc++abi-dev \
+          pkg-config \
+          zlib1g-dev \
+          libssl-dev \
+          bzip2-dev \
+          sqlite3-dev \
     - name: Install CLANG
       run: apt-get install clang -y
     - name: Check clang version
@@ -80,9 +87,10 @@ jobs:
         make -j$(nproc)
         make install
         cd ..
-        export PATH=$OMPI_INSTALL_PATH/bin:$PATH
+        export PATH=$OMPI_INSTALL_PATH/bin:$PATH >> $GITHUB_ENV
     - name: Show MPI version
       run: |
+        echo $PATH
         export CC=clang
         export CXX=clang++
         mpicc --version

From 762b6a53335735c1b43913e21f3a604b2eb33ab7 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 11:24:45 +0100
Subject: [PATCH 26/99] Trigger [run ci]

---
 .../workflows/tests_cmake_t8code_w_other_compilers.yml | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 1140e46cd5..c9d7f762ae 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -67,11 +67,11 @@ jobs:
       run: |
         apt-get install -y wget tar lld make \
           libc6-dev libc++-dev libc++abi-dev \
-          pkg-config \
-          zlib1g-dev \
-          libssl-dev \
-          bzip2-dev \
-          sqlite3-dev \
+          pkg-config
+          # zlib1g-dev \
+          # libssl-dev \
+          # bzip2-dev \
+          # sqlite3-dev \
     - name: Install CLANG
       run: apt-get install clang -y
     - name: Check clang version

From 3f4daba2fd96d84cf450be3cc0ee11a86e0a8a80 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 11:38:04 +0100
Subject: [PATCH 27/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index c9d7f762ae..db836dd120 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -87,7 +87,9 @@ jobs:
         make -j$(nproc)
         make install
         cd ..
+        echo "OMPI_INSTALL_PATH= ${OMPI_INSTALL_PATH}"
         export PATH=$OMPI_INSTALL_PATH/bin:$PATH >> $GITHUB_ENV
+        echo "PATH= ${PATH}"
     - name: Show MPI version
       run: |
         echo $PATH

From 08f9fc108ade1ae638f57f464c00040843c80af1 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 11:49:28 +0100
Subject: [PATCH 28/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index db836dd120..b12805af12 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -86,10 +86,9 @@ jobs:
         CC=clang CXX=clang++ ./configure --prefix=$OMPI_INSTALL_PATH
         make -j$(nproc)
         make install
-        cd ..
         echo "OMPI_INSTALL_PATH= ${OMPI_INSTALL_PATH}"
-        export PATH=$OMPI_INSTALL_PATH/bin:$PATH >> $GITHUB_ENV
-        echo "PATH= ${PATH}"
+        ls $OMPI_INSTALL_PATH
+        echo "${OMPI_INSTALL_PATH}"" >> $GITHUB_PATH
     - name: Show MPI version
       run: |
         echo $PATH

From f2d002d7de8ab177f75ba2b3b21fab25804862a0 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 12:05:03 +0100
Subject: [PATCH 29/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index b12805af12..cbb4ce17bb 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -88,7 +88,7 @@ jobs:
         make install
         echo "OMPI_INSTALL_PATH= ${OMPI_INSTALL_PATH}"
         ls $OMPI_INSTALL_PATH
-        echo "${OMPI_INSTALL_PATH}"" >> $GITHUB_PATH
+        echo "${OMPI_INSTALL_PATH}" >> $GITHUB_PATH
     - name: Show MPI version
       run: |
         echo $PATH

From 55a103bf1291e9a3adcb57de2ea2fcd2441e5b2e Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 12:14:33 +0100
Subject: [PATCH 30/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index cbb4ce17bb..5e9953adab 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -87,8 +87,8 @@ jobs:
         make -j$(nproc)
         make install
         echo "OMPI_INSTALL_PATH= ${OMPI_INSTALL_PATH}"
-        ls $OMPI_INSTALL_PATH
-        echo "${OMPI_INSTALL_PATH}" >> $GITHUB_PATH
+        ls $OMPI_INSTALL_PATH/bin
+        echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
     - name: Show MPI version
       run: |
         echo $PATH

From 4224c500522544f624203941bb2d3dabafdad137 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 13:32:10 +0100
Subject: [PATCH 31/99] Trigger [run ci]

---
 .../tests_cmake_t8code_w_other_compilers.yml  | 20 ++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 5e9953adab..1c4562f0a9 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -91,17 +91,19 @@ jobs:
         echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
     - name: Show MPI version
       run: |
-        echo $PATH
-        export CC=clang
-        export CXX=clang++
+        # echo $PATH
+        # export CC=clang
+        # export CXX=clang++
         mpicc --version
+    - name: Show folder content
+      run: ls
       # This seems to be necessary because of the docker container
-#     - name: disable ownership checks
-#       run: git config --global --add safe.directory '*'
-#     - name: init submodules
-#       run: git submodule init
-#     - name: update submodules
-#       run: git submodule update
+    - name: disable ownership checks
+      run: git config --global --add safe.directory '*'
+    - name: init submodules
+      run: git submodule init
+    - name: update submodules
+      run: git submodule update
 #     - name: Get input vars
 #       run: export MAKEFLAGS="${{ inputs.MAKEFLAGS }}"
 #         && export MPI="${{ inputs.MPI }}"

From fa1f9bb08222fe68fc574697821e82632bf60df3 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 13:38:58 +0100
Subject: [PATCH 32/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 1c4562f0a9..383d6af7e3 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -67,7 +67,8 @@ jobs:
       run: |
         apt-get install -y wget tar lld make \
           libc6-dev libc++-dev libc++abi-dev \
-          pkg-config
+          pkg-config \
+          git
           # zlib1g-dev \
           # libssl-dev \
           # bzip2-dev \

From 5da01e0f4ec6b4baa18e5e66367ae62a43d6c216 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 13:51:31 +0100
Subject: [PATCH 33/99] Trigger [run ci]

---
 .../workflows/tests_cmake_t8code_w_other_compilers.yml    | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 383d6af7e3..e7acc2d0f0 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -97,10 +97,12 @@ jobs:
         # export CXX=clang++
         mpicc --version
     - name: Show folder content
-      run: ls
+      run: |
+        ls
+        ls .git
       # 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

From 8f428238c694b6feda4cef22749a2d8a3856a868 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 14:09:35 +0100
Subject: [PATCH 34/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index e7acc2d0f0..db074eb5d5 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -61,6 +61,8 @@ jobs:
     - uses: actions/checkout@v6
       with:
         fetch-depth: 0
+    - name: Git status
+      run: git status
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
     - name: Install some basic packages

From 14f0231ceb4a9f4d70ed98d4affb302eed1a7430 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 14:16:30 +0100
Subject: [PATCH 35/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index db074eb5d5..460508a01f 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -53,7 +53,7 @@ jobs:
   t8code_cmake_tests:
     timeout-minutes: 60
     runs-on: ubuntu-latest
-    container: ubuntu:22.04
+    container: dlramr/t8code-ubuntu:t8-dependencies
     steps:
 #
 # Setup

From 9dfbe5ff016c29cc30be394926a0104ea241a371 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 14:33:17 +0100
Subject: [PATCH 36/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 --
 1 file changed, 2 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 460508a01f..d3ac892d38 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -61,8 +61,6 @@ jobs:
     - uses: actions/checkout@v6
       with:
         fetch-depth: 0
-    - name: Git status
-      run: git status
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
     - name: Install some basic packages

From 4a6fea19c441e151055b0a35c7ec7bead03d083a Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 14:47:05 +0100
Subject: [PATCH 37/99] Trigger [run ci]

---
 .../tests_cmake_t8code_w_other_compilers.yml  | 24 ++++++++-----------
 1 file changed, 10 insertions(+), 14 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index d3ac892d38..6e0618c1a7 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -91,29 +91,25 @@ jobs:
         ls $OMPI_INSTALL_PATH/bin
         echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
     - name: Show MPI version
-      run: |
-        # echo $PATH
-        # export CC=clang
-        # export CXX=clang++
-        mpicc --version
+      run: mpicc --version
     - name: Show folder content
       run: |
         ls
         ls .git
       # This seems to be necessary because of the docker container
-    # - name: disable ownership checks
-    #   run: git config --global --add safe.directory '*'
+    - name: disable ownership checks
+      run: git config --global --add safe.directory '*'
     - name: init submodules
       run: git submodule init
     - name: update submodules
       run: git submodule update
-#     - name: Get input vars
-#       run: export MAKEFLAGS="${{ 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" >> $GITHUB_ENV
+    - name: Get input vars
+      run: export MAKEFLAGS="${{ 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
 # #
 # #  T8CODE
 # #

From 04976c2501d50b0f5c9cfec430f805d132527384 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 15:07:28 +0100
Subject: [PATCH 38/99] Trigger [run ci]

---
 .../tests_cmake_t8code_w_other_compilers.yml  | 62 +++++++++++--------
 1 file changed, 36 insertions(+), 26 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 6e0618c1a7..04d087d576 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -87,11 +87,21 @@ jobs:
         CC=clang CXX=clang++ ./configure --prefix=$OMPI_INSTALL_PATH
         make -j$(nproc)
         make install
-        echo "OMPI_INSTALL_PATH= ${OMPI_INSTALL_PATH}"
+        echo OMPI_INSTALL_PATH="${OMPI_INSTALL_PATH}" >> $GITHUB_ENV
         ls $OMPI_INSTALL_PATH/bin
         echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
     - name: Show MPI version
       run: mpicc --version
+    - name: Export CLANG compiler flags
+      run: |
+        export CC=clang
+        export CXX=clang++
+        export MPICC={OMPI_INSTALL_PATH}/bin/mpiccc
+        export MPICXX={OMPI_INSTALL_PATH}/bin/mpicxx
+        echo CC="$CC" >> $GITHUB_ENV
+        echo CXX="$CXX" >> $GITHUB_ENV
+        echo MPICC="$MPICC" >> $GITHUB_ENV
+        echo MPICXX="$MPICXX" >> $GITHUB_ENV
     - name: Show folder content
       run: |
         ls
@@ -110,31 +120,31 @@ jobs:
         && echo MAKEFLAGS="$MAKEFLAGS" >> $GITHUB_ENV
         && echo MPI="$MPI" >> $GITHUB_ENV
         && echo BUILD_TYPE="$BUILD_TYPE" >> $GITHUB_ENV
-# #
-# #  T8CODE
-# #
-#     # build config vars
-#     - name: Set test level
-#       run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
-#            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
-#     - name: build config variables
-#       run: export CONFIG_OPTIONS="${TEST_LEVEL_FLAG} -GNinja -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_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
-#         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
-#     # cmake and test
-#     - name: Printing MPI compiler info
-#       run: mpicc --version && mpirun --version
-#     - name: Printing GCC compiler info
-#       run: gcc --version && g++ --version
-#     - name: echo cmake line
-#       run: echo cmake ../ $CONFIG_OPTIONS
-#     - name: cmake
-#       run: mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
-#     - name: OnFailUploadLog
-#       if: failure()
-#       uses: actions/upload-artifact@v5
-#       with:
-#         name: cmake_w_submodules_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
-#         path: build/CMakeFiles/CMakeOutput.log
+#
+#  T8CODE
+#
+    # build config vars
+    - name: Set test level
+      run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
+           && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
+    - name: build config variables
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicc -DCMAKE_CXX_COMPILER={OMPI_INSTALL_PATH}/bin/mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=ON -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
+        && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
+    # cmake and test
+    - name: Printing MPI compiler info
+      run: mpicc --version && mpirun --version
+    - name: Printing GCC compiler info
+      run: gcc --version && g++ --version
+    - name: echo cmake line
+      run: echo cmake ../ $CONFIG_OPTIONS
+    - name: cmake
+      run: mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
+    # - name: OnFailUploadLog
+    #   if: failure()
+    #   uses: actions/upload-artifact@v5
+    #   with:
+    #     name: cmake_w_submodules_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+    #     path: build/CMakeFiles/CMakeOutput.log
 #     - name: ninja
 #       run: cd build && ninja $MAKEFLAGS
 #     - name: ninja install

From 80afe9fef3f6fe56a2c890006a0b82b71be63045 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 15:58:55 +0100
Subject: [PATCH 39/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 04d087d576..d3c10373a4 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -128,7 +128,7 @@ jobs:
       run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
     - name: build config variables
-      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicc -DCMAKE_CXX_COMPILER={OMPI_INSTALL_PATH}/bin/mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=ON -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicc -DCMAKE_CXX_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=ON -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # cmake and test
     - name: Printing MPI compiler info

From d6475a19f5aaec5301b2f4c40311ae854d583c4c Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 16:15:06 +0100
Subject: [PATCH 40/99] Trigger [run ci]

---
 .../tests_cmake_t8code_w_other_compilers.yml  | 50 +++++++++----------
 1 file changed, 24 insertions(+), 26 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index d3c10373a4..82f4b2a1f1 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -133,34 +133,32 @@ jobs:
     # cmake and test
     - name: Printing MPI compiler info
       run: mpicc --version && mpirun --version
-    - name: Printing GCC compiler info
-      run: gcc --version && g++ --version
     - name: echo cmake line
       run: echo cmake ../ $CONFIG_OPTIONS
     - name: cmake
       run: mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
-    # - name: OnFailUploadLog
-    #   if: failure()
-    #   uses: actions/upload-artifact@v5
-    #   with:
-    #     name: cmake_w_submodules_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
-    #     path: build/CMakeFiles/CMakeOutput.log
-#     - name: ninja
-#       run: cd build && ninja $MAKEFLAGS
-#     - name: ninja install
-#       run: cd build && ninja install $MAKEFLAGS
-#     - name: serial tests (if MPI is enabled)
-#       run: cd build && ctest $MAKEFLAGS -R _serial
-#       if: ${{ inputs.MPI == 'ON' }}
-#     - name: parallel tests (if MPI is enabled)
-#       run: cd build && ctest -R _parallel
+    - name: OnFailUploadLog
+      if: failure()
+      uses: actions/upload-artifact@v5
+      with:
+        name: cmake_w_other_compilers_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+        path: build/CMakeFiles/CMakeOutput.log
+    - name: ninja
+      run: cd build && ninja $MAKEFLAGS
+    - name: ninja install
+      run: cd build && ninja install $MAKEFLAGS
+    - name: serial tests (if MPI is enabled)
+      run: cd build && ctest $MAKEFLAGS -R _serial
 #       if: ${{ inputs.MPI == 'ON' }}
-#     - name: tests (if MPI is disabled)
-#       run: cd build && ctest $MAKEFLAGS
-#       if: ${{ inputs.MPI == 'OFF' }}
-#     - name: OnFailUploadLog
-#       if: failure()
-#       uses: actions/upload-artifact@v5
-#       with:
-#         name: test-suite_w_submodules_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
-#         path: build/Testing/Temporary/LastTest.log
+    - name: parallel tests (if MPI is enabled)
+      run: cd build && ctest -R _parallel
+      if: ${{ inputs.MPI == 'ON' }}
+    - name: tests (if MPI is disabled)
+      run: cd build && ctest $MAKEFLAGS
+      if: ${{ inputs.MPI == 'OFF' }}
+    - name: OnFailUploadLog
+      if: failure()
+      uses: actions/upload-artifact@v5
+      with:
+        name: test-suite_w_other_compilers_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+        path: build/Testing/Temporary/LastTest.log

From 99a2ee6fec734fd4e7d71c126cbb5996ca6912c4 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 18 Dec 2025 16:46:38 +0100
Subject: [PATCH 41/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 82f4b2a1f1..bddc343a8e 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -128,7 +128,7 @@ jobs:
       run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
     - name: build config variables
-      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicc -DCMAKE_CXX_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=ON -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicc -DCMAKE_CXX_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # cmake and test
     - name: Printing MPI compiler info

From 2b0520bb31141ce6e30ae3e0c76e002ba04a4241 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 19 Dec 2025 10:48:55 +0100
Subject: [PATCH 42/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index bddc343a8e..c2b07d21e1 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -152,6 +152,9 @@ jobs:
 #       if: ${{ inputs.MPI == 'ON' }}
     - name: parallel tests (if MPI is enabled)
       run: cd build && ctest -R _parallel
+      env:
+        OMPI_ALLOW_RUN_AS_ROOT: 1
+        OMPI_ALLOW_RUN_AS_ROOT_CONFIRM: 1
       if: ${{ inputs.MPI == 'ON' }}
     - name: tests (if MPI is disabled)
       run: cd build && ctest $MAKEFLAGS

From 50b91b9dae37ce4ec1fbe506e1b02b56b7acd782 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 19 Dec 2025 11:08:38 +0100
Subject: [PATCH 43/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index c2b07d21e1..55abc4170d 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -155,6 +155,7 @@ jobs:
       env:
         OMPI_ALLOW_RUN_AS_ROOT: 1
         OMPI_ALLOW_RUN_AS_ROOT_CONFIRM: 1
+        OMPI_MCA_rmaps_base_oversubscribe: 1
       if: ${{ inputs.MPI == 'ON' }}
     - name: tests (if MPI is disabled)
       run: cd build && ctest $MAKEFLAGS

From cef471979e4e57cabecdfa03f99a0baa5fda2ac5 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 19 Dec 2025 11:41:58 +0100
Subject: [PATCH 44/99] Trigger [run ci]

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

diff --git a/.github/workflows/tests_cmake_testsuite.yml b/.github/workflows/tests_cmake_testsuite.yml
index 3568f00d69..e2707e796b 100644
--- a/.github/workflows/tests_cmake_testsuite.yml
+++ b/.github/workflows/tests_cmake_testsuite.yml
@@ -229,7 +229,7 @@ jobs:
       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.
+      TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_BASIC' || 'T8_TEST_LEVEL_BASIC' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
       COMPILER: CLANG
 
   # Run t8code tests with shipped submodules. This test is only for the build system, so only one config is tested.

From 8e1741596d4dd21a33a1ffa1a281891a4b87fef7 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 5 Jan 2026 14:40:11 +0100
Subject: [PATCH 45/99] Try fixing stalling MPI issue

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 ++
 src/t8_netcdf.c                                            | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 55abc4170d..b82c490bf1 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -156,6 +156,8 @@ jobs:
         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
diff --git a/src/t8_netcdf.c b/src/t8_netcdf.c
index faf8a34423..2b5c74fa23 100644
--- a/src/t8_netcdf.c
+++ b/src/t8_netcdf.c
@@ -46,7 +46,7 @@ t8_netcdf_create_integer_var (const char *var_name, const char *var_long_name, c
                               sc_array_t *var_data)
 {
   t8_netcdf_variable_type_t var_type;
-  /* Check whether 32-bit (4-byte) integer or 64-bit integer data sholud be written */
+  /* Check whether 32-bit (4-byte) integer or 64-bit integer data should be written */
   var_type = (var_data->elem_size > 4) ? T8_NETCDF_INT64 : T8_NETCDF_INT;
   return t8_netcdf_create_var (var_type, var_name, var_long_name, var_unit, var_data);
 }

From b9435931b6e4aede373e40f3bfba73de9df28c7d Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 5 Jan 2026 14:49:53 +0100
Subject: [PATCH 46/99] Trigger [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index b82c490bf1..8d697ac69b 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -122,7 +122,7 @@ jobs:
         && echo BUILD_TYPE="$BUILD_TYPE" >> $GITHUB_ENV
 #
 #  T8CODE
-#
+# -------
     # build config vars
     - name: Set test level
       run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"

From 782f17026c284d0d908a97c2ef9840f83159eea0 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 5 Jan 2026 15:31:44 +0100
Subject: [PATCH 47/99] Use new docker image t8-clang-dependencies [run ci]

---
 .../tests_cmake_t8code_w_other_compilers.yml  | 52 +++++++++----------
 1 file changed, 26 insertions(+), 26 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 8d697ac69b..3e8811966f 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -53,7 +53,7 @@ jobs:
   t8code_cmake_tests:
     timeout-minutes: 60
     runs-on: ubuntu-latest
-    container: dlramr/t8code-ubuntu:t8-dependencies
+    container: dlramr/t8code-ubuntu:t8-clang-dependencies
     steps:
 #
 # Setup
@@ -63,33 +63,33 @@ jobs:
         fetch-depth: 0
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
-    - name: Install some basic packages
-      run: |
-        apt-get install -y wget tar lld make \
-          libc6-dev libc++-dev libc++abi-dev \
-          pkg-config \
-          git
-          # zlib1g-dev \
-          # libssl-dev \
-          # bzip2-dev \
-          # sqlite3-dev \
-    - name: Install CLANG
-      run: apt-get install clang -y
+    # - name: Install some basic packages
+    #   run: |
+    #     apt-get install -y wget tar lld make \
+    #       libc6-dev libc++-dev libc++abi-dev \
+    #       pkg-config \
+    #       git
+    #       # zlib1g-dev \
+    #       # libssl-dev \
+    #       # bzip2-dev \
+    #       # sqlite3-dev \
+    # - name: Install CLANG
+    #   run: apt-get install clang -y
     - name: Check clang version
       run: clang --version
-    - name: Install openmpi with CLANG
-      run: |
-        mkdir install_ompi_clang
-        export OMPI_INSTALL_PATH=$(pwd)/install_ompi_clang
-        wget https://download.open-mpi.org/release/open-mpi/v4.1/openmpi-4.1.6.tar.gz
-        tar xf openmpi-4.1.6.tar.gz
-        cd openmpi-4.1.6
-        CC=clang CXX=clang++ ./configure --prefix=$OMPI_INSTALL_PATH
-        make -j$(nproc)
-        make install
-        echo OMPI_INSTALL_PATH="${OMPI_INSTALL_PATH}" >> $GITHUB_ENV
-        ls $OMPI_INSTALL_PATH/bin
-        echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
+    # - name: Install openmpi with CLANG
+    #   run: |
+    #     mkdir install_ompi_clang
+    #     export OMPI_INSTALL_PATH=$(pwd)/install_ompi_clang
+    #     wget https://download.open-mpi.org/release/open-mpi/v4.1/openmpi-4.1.6.tar.gz
+    #     tar xf openmpi-4.1.6.tar.gz
+    #     cd openmpi-4.1.6
+    #     CC=clang CXX=clang++ ./configure --prefix=$OMPI_INSTALL_PATH
+    #     make -j$(nproc)
+    #     make install
+    #     echo OMPI_INSTALL_PATH="${OMPI_INSTALL_PATH}" >> $GITHUB_ENV
+    #     ls $OMPI_INSTALL_PATH/bin
+    #     echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
     - name: Show MPI version
       run: mpicc --version
     - name: Export CLANG compiler flags

From 202a2c327848fd60ba3d84e2c8216628a3dba214 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 5 Jan 2026 15:37:23 +0100
Subject: [PATCH 48/99] Add self-compiled openmpi version to PATH [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 3e8811966f..17faa7d5b8 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -90,8 +90,6 @@ jobs:
     #     echo OMPI_INSTALL_PATH="${OMPI_INSTALL_PATH}" >> $GITHUB_ENV
     #     ls $OMPI_INSTALL_PATH/bin
     #     echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
-    - name: Show MPI version
-      run: mpicc --version
     - name: Export CLANG compiler flags
       run: |
         export CC=clang
@@ -102,6 +100,9 @@ jobs:
         echo CXX="$CXX" >> $GITHUB_ENV
         echo MPICC="$MPICC" >> $GITHUB_ENV
         echo MPICXX="$MPICXX" >> $GITHUB_ENV
+        echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
+    - name: Show MPI version
+      run: mpicc --version
     - name: Show folder content
       run: |
         ls

From 2cdcf1f69bbbcd69a84e63e56305b5cc2f28f210 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 5 Jan 2026 16:00:22 +0100
Subject: [PATCH 49/99] Install cmake [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index 17faa7d5b8..ff79dc0a5f 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -63,6 +63,9 @@ jobs:
         fetch-depth: 0
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
+    - name: Install missing packages (to be added to image)
+      run: |
+        apt-get install -y cmake
     # - name: Install some basic packages
     #   run: |
     #     apt-get install -y wget tar lld make \

From 2fec6f785d59d775a939d0fee7b633cc9ec57145 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 5 Jan 2026 16:02:49 +0100
Subject: [PATCH 50/99] Install ninja-build [run ci]

---
 .github/workflows/tests_cmake_t8code_w_other_compilers.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
index ff79dc0a5f..fdb658b251 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
@@ -65,7 +65,7 @@ jobs:
       run: apt-get update && apt-get upgrade -y
     - name: Install missing packages (to be added to image)
       run: |
-        apt-get install -y cmake
+        apt-get install -y cmake ninja-build
     # - name: Install some basic packages
     #   run: |
     #     apt-get install -y wget tar lld make \

From 6ceba138c5868918e059d57cdffca112164c216c Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Mon, 5 Jan 2026 16:19:34 +0100
Subject: [PATCH 51/99] Some cleanup [run ci]

---
 ...> tests_cmake_t8code_w_clang_compiler.yml} | 44 ++-----------------
 .github/workflows/tests_cmake_testsuite.yml   | 25 +++++------
 2 files changed, 16 insertions(+), 53 deletions(-)
 rename .github/workflows/{tests_cmake_t8code_w_other_compilers.yml => tests_cmake_t8code_w_clang_compiler.yml} (76%)

diff --git a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml b/.github/workflows/tests_cmake_t8code_w_clang_compiler.yml
similarity index 76%
rename from .github/workflows/tests_cmake_t8code_w_other_compilers.yml
rename to .github/workflows/tests_cmake_t8code_w_clang_compiler.yml
index fdb658b251..342d2df9cf 100644
--- a/.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+++ b/.github/workflows/tests_cmake_t8code_w_clang_compiler.yml
@@ -1,11 +1,11 @@
-name: CMake tests t8code with other compilers
+name: CMake tests t8code with Clang compiler
 
 
 #  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) 2024 the developers
+#  Copyright (C) 2025 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
@@ -44,10 +44,6 @@ on:
         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'
-      COMPILER:
-        required: true
-        type: string
-        description: 'Compiler (CLANG)'
 
 jobs:
   t8code_cmake_tests:
@@ -63,36 +59,8 @@ jobs:
         fetch-depth: 0
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
-    - name: Install missing packages (to be added to image)
-      run: |
-        apt-get install -y cmake ninja-build
-    # - name: Install some basic packages
-    #   run: |
-    #     apt-get install -y wget tar lld make \
-    #       libc6-dev libc++-dev libc++abi-dev \
-    #       pkg-config \
-    #       git
-    #       # zlib1g-dev \
-    #       # libssl-dev \
-    #       # bzip2-dev \
-    #       # sqlite3-dev \
-    # - name: Install CLANG
-    #   run: apt-get install clang -y
     - name: Check clang version
       run: clang --version
-    # - name: Install openmpi with CLANG
-    #   run: |
-    #     mkdir install_ompi_clang
-    #     export OMPI_INSTALL_PATH=$(pwd)/install_ompi_clang
-    #     wget https://download.open-mpi.org/release/open-mpi/v4.1/openmpi-4.1.6.tar.gz
-    #     tar xf openmpi-4.1.6.tar.gz
-    #     cd openmpi-4.1.6
-    #     CC=clang CXX=clang++ ./configure --prefix=$OMPI_INSTALL_PATH
-    #     make -j$(nproc)
-    #     make install
-    #     echo OMPI_INSTALL_PATH="${OMPI_INSTALL_PATH}" >> $GITHUB_ENV
-    #     ls $OMPI_INSTALL_PATH/bin
-    #     echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
     - name: Export CLANG compiler flags
       run: |
         export CC=clang
@@ -106,10 +74,6 @@ jobs:
         echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
     - name: Show MPI version
       run: mpicc --version
-    - name: Show folder content
-      run: |
-        ls
-        ls .git
       # This seems to be necessary because of the docker container
     - name: disable ownership checks
       run: git config --global --add safe.directory '*'
@@ -145,7 +109,7 @@ jobs:
       if: failure()
       uses: actions/upload-artifact@v5
       with:
-        name: cmake_w_other_compilers_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+        name: cmake_w_clang_compiler_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
         path: build/CMakeFiles/CMakeOutput.log
     - name: ninja
       run: cd build && ninja $MAKEFLAGS
@@ -170,5 +134,5 @@ jobs:
       if: failure()
       uses: actions/upload-artifact@v5
       with:
-        name: test-suite_w_other_compilers_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+        name: test-suite_w_clang_compiler_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
         path: build/Testing/Temporary/LastTest.log
diff --git a/.github/workflows/tests_cmake_testsuite.yml b/.github/workflows/tests_cmake_testsuite.yml
index e2707e796b..5f82d1e7e7 100644
--- a/.github/workflows/tests_cmake_testsuite.yml
+++ b/.github/workflows/tests_cmake_testsuite.yml
@@ -213,31 +213,30 @@ jobs:
   #     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_other_compilers_tests:
+  t8code_w_clang_compiler_tests:
     needs: fine_grained_trigger
     secrets: inherit
     if: ${{ needs.fine_grained_trigger.outputs.run_ci == 'true' }}
-    uses: ./.github/workflows/tests_cmake_t8code_w_other_compilers.yml
+    uses: ./.github/workflows/tests_cmake_t8code_w_clang_compiler.yml
     strategy:
       fail-fast: false
-      # matrix:
-      #   MPI: [OFF, ON]
-      #   BUILD_TYPE: [Debug, Release]
-      #   include:
-      #     - MAKEFLAGS: -j4
+      matrix:
+        MPI: [ON]
+        BUILD_TYPE: [Debug, Release]
+        include:
+          - MAKEFLAGS: -j4
     with:
-      MAKEFLAGS: -j4
-      MPI: ON
-      BUILD_TYPE: Debug
-      TEST_LEVEL: ${{ github.event_name == 'pull_request' && 'T8_TEST_LEVEL_BASIC' || 'T8_TEST_LEVEL_BASIC' }} # Set TEST_LEVEL to medium if the event is a PR, otherwise full.
-      COMPILER: CLANG
+      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 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/tests_cmake_t8code_w_other_compilers.yml
+  #   uses: ./.github/workflows/tests_cmake_t8code_w_clang_compiler.yml
   #   with:
   #     MAKEFLAGS: -j4
   #     MPI: ON

From 2d27ec983404cb525292d2eff13a7a874b74fee9 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 6 Jan 2026 09:12:41 +0100
Subject: [PATCH 52/99] Added some documentation [run ci]

---
 .../tests_cmake_t8code_w_clang_compiler.yml   | 40 ++++++++++++++-----
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/.github/workflows/tests_cmake_t8code_w_clang_compiler.yml b/.github/workflows/tests_cmake_t8code_w_clang_compiler.yml
index 342d2df9cf..d57ed26c2b 100644
--- a/.github/workflows/tests_cmake_t8code_w_clang_compiler.yml
+++ b/.github/workflows/tests_cmake_t8code_w_clang_compiler.yml
@@ -21,11 +21,19 @@ name: CMake tests t8code with Clang compiler
 #  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 with the Clang compiler
+#  and openmpi. It was added because all of t8code's remaining CI workflows rely
+#  on gcc and mpich, hence missing Clang- or openmpi-specific issues.
+#  To reduce runtime, (for now) only Debug mode with MPI is tested; also, no external
+#  libraries like VTK, OpenCASCADE etc. are covered.
+
 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.
     inputs:
       MAKEFLAGS:
         required: true
@@ -47,13 +55,16 @@ on:
 
 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.
     timeout-minutes: 60
     runs-on: ubuntu-latest
     container: dlramr/t8code-ubuntu:t8-clang-dependencies
     steps:
-#
-# Setup
-#
+  #
+  # Part 1: Preparation
+  # -------------------
     - uses: actions/checkout@v6
       with:
         fetch-depth: 0
@@ -88,39 +99,45 @@ jobs:
         && echo MAKEFLAGS="$MAKEFLAGS" >> $GITHUB_ENV
         && echo MPI="$MPI" >> $GITHUB_ENV
         && echo BUILD_TYPE="$BUILD_TYPE" >> $GITHUB_ENV
-#
-#  T8CODE
-# -------
-    # build config vars
+  #
+  # Part 2: Build t8code
+  # --------------------
+    # Define build config
     - name: Set test level
       run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
     - name: build config variables
       run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicc -DCMAKE_CXX_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
-    # cmake and test
-    - name: Printing MPI compiler info
-      run: mpicc --version && mpirun --version
+    # Run cmake
     - name: echo cmake line
       run: echo cmake ../ $CONFIG_OPTIONS
     - name: cmake
       run: mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
+    # On failure, upload logs
     - name: OnFailUploadLog
       if: failure()
       uses: actions/upload-artifact@v5
       with:
         name: cmake_w_clang_compiler_${{ 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
+  # ------------------------
+    # Run serial and parallel tests.
     - 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:
+        # 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
@@ -130,6 +147,7 @@ jobs:
     - 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@v5

From 40f72cbc8c86450fd43e2659a702ebf3cbf99074 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 6 Jan 2026 09:53:20 +0100
Subject: [PATCH 53/99] Adjusted to new workflow names

---
 ...r.yml => test_t8code_w_clang_and_ompi.yml} |  17 +-
 .github/workflows/testsuite.yml               | 244 ++++++++++--------
 2 files changed, 142 insertions(+), 119 deletions(-)
 rename .github/workflows/{tests_cmake_t8code_w_clang_compiler.yml => test_t8code_w_clang_and_ompi.yml} (86%)

diff --git a/.github/workflows/tests_cmake_t8code_w_clang_compiler.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
similarity index 86%
rename from .github/workflows/tests_cmake_t8code_w_clang_compiler.yml
rename to .github/workflows/test_t8code_w_clang_and_ompi.yml
index d57ed26c2b..ff70b5a5c7 100644
--- a/.github/workflows/tests_cmake_t8code_w_clang_compiler.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -1,4 +1,4 @@
-name: CMake tests t8code with Clang compiler
+name: CMake tests t8code with Clang compiler and OpenMPI
 
 
 #  This file is part of t8code.
@@ -57,7 +57,8 @@ 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.
+  #                  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: ubuntu-latest
     container: dlramr/t8code-ubuntu:t8-clang-dependencies
@@ -70,13 +71,13 @@ jobs:
         fetch-depth: 0
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
-    - name: Check clang version
+    - name: Check Clang version
       run: clang --version
-    - name: Export CLANG compiler flags
+    - name: Export Clang compiler flags (not all strictly required, but safety first)
       run: |
         export CC=clang
         export CXX=clang++
-        export MPICC={OMPI_INSTALL_PATH}/bin/mpiccc
+        export MPICC={OMPI_INSTALL_PATH}/bin/mpicc
         export MPICXX={OMPI_INSTALL_PATH}/bin/mpicxx
         echo CC="$CC" >> $GITHUB_ENV
         echo CXX="$CXX" >> $GITHUB_ENV
@@ -107,7 +108,7 @@ jobs:
       run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
     - name: build config variables
-      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicc -DCMAKE_CXX_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=${MPICC} -DCMAKE_CXX_COMPILER=${MPICXX} ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # Run cmake
     - name: echo cmake line
@@ -119,7 +120,7 @@ jobs:
       if: failure()
       uses: actions/upload-artifact@v5
       with:
-        name: cmake_w_clang_compiler_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+        name: cmake_w_clang_and_ompi_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
         path: build/CMakeFiles/CMakeOutput.log
     # Build with ninja
     - name: ninja
@@ -152,5 +153,5 @@ jobs:
       if: failure()
       uses: actions/upload-artifact@v5
       with:
-        name: test-suite_w_clang_compiler_${{ inputs.BUILD_TYPE }}_MPI_${{ inputs.MPI }}.log
+        name: test-suite_w_clang_and_ompi_${{ 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 4c10076a54..55a9552d9a 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -105,81 +105,138 @@ jobs:
           exit 0
         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 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 }}
 
-  # 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 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:
+  #     MAKEFLAGS: -j4
+  #     MPI: ON
+  #     BUILD_TYPE: Debug
+  #     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 }}
+
+  # # 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 linkage tests with and without MPI and in serial and debug mode
-  t8code_api_tests:
-    needs: preparation
-    uses: ./.github/workflows/test_t8code_api.yml
+  # 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 used Debug mode with MPI on and does not link to 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] # For now the fortran API only supports building with MPI
-        BUILD_TYPE: [Debug, Release]
+        MPI: [ON]
+        BUILD_TYPE: [Debug]
         include:
           - MAKEFLAGS: -j4
     with:
@@ -188,47 +245,12 @@ 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.
 
-  # 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:
-      MAKEFLAGS: -j4
-      MPI: ON
-      BUILD_TYPE: Debug
-      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 }}
-
-  # 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.
+  # # Build doxygen documentation and check for errors / warnings.
+  # t8code_doxygen_check:
+  #   uses: ./.github/workflows/check_doxygen.yml
 
-  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 2deb92059e3807a0144177c1af7eb554b6750345 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 6 Jan 2026 09:56:02 +0100
Subject: [PATCH 54/99] Trigger CI [run ci]

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

diff --git a/.github/workflows/testsuite.yml b/.github/workflows/testsuite.yml
index 55a9552d9a..41ecdd5eb1 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -248,7 +248,7 @@ jobs:
   # # 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

From 7956f3860b0074c8528f5065d5414ecbc0cfe11e Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 6 Jan 2026 10:23:39 +0100
Subject: [PATCH 55/99] Introduced some sanity checks [run ci]

---
 .../test_t8code_w_clang_and_ompi.yml          | 41 +++++++++++++------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index ff70b5a5c7..80ad6bff76 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -73,19 +73,36 @@ jobs:
       run: apt-get update && apt-get upgrade -y
     - name: Check Clang version
       run: clang --version
-    - name: Export Clang compiler flags (not all strictly required, but safety first)
+    - name: Verify gcc is absent
+      run: ! command -v gcc
+    # - name: Export Clang compiler flags (not all strictly required, but safety first)
+    #   run: |
+    #     export CC=clang
+    #     export CXX=clang++
+    #     export MPICC=${OMPI_INSTALL_PATH}/bin/mpicc
+    #     export MPICXX=${OMPI_INSTALL_PATH}/bin/mpicxx
+    #     echo CC="$CC" >> $GITHUB_ENV
+    #     echo CXX="$CXX" >> $GITHUB_ENV
+    #     echo MPICC="$MPICC" >> $GITHUB_ENV
+    #     echo MPICXX="$MPICXX" >> $GITHUB_ENV
+    #     echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
+    - name: Make sure MPI was built with CLANG
+      # Note: If "clang" is not found, the workflow is exited (due to fail-early mode)
       run: |
-        export CC=clang
-        export CXX=clang++
-        export MPICC={OMPI_INSTALL_PATH}/bin/mpicc
-        export MPICXX={OMPI_INSTALL_PATH}/bin/mpicxx
-        echo CC="$CC" >> $GITHUB_ENV
-        echo CXX="$CXX" >> $GITHUB_ENV
-        echo MPICC="$MPICC" >> $GITHUB_ENV
-        echo MPICXX="$MPICXX" >> $GITHUB_ENV
-        echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
-    - name: Show MPI version
-      run: mpicc --version
+        mpicc --version > mpi_version_output
+        cat mpi_version_output
+        grep -i "clang" mpi_version_output
+        rm mpi_version_output
+    - name: Assert correct MPI paths
+      run: |
+        mpicc --showme:compile | grep -q "${OMPI_INSTALL_PATH}"
+        mpicc --showme:link    | grep -q "${OMPI_INSTALL_PATH}"
+    # - name: Make sure the right MPI path is used
+    #   run: |
+    #     which mpicc > which_mpi_output
+    #     cat which_mpi_output
+    #     grep -i "${OMPI_INSTALL_PATH}" which_mpi_output
+    #     rm which_mpi_output
       # This seems to be necessary because of the docker container
     - name: disable ownership checks
       run: git config --global --add safe.directory '*'

From 7b5d55c10656c4ef3120502e4db45e88ab614369 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 6 Jan 2026 10:27:18 +0100
Subject: [PATCH 56/99] Fix mpi paths in cmake command [run ci]

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 80ad6bff76..869f7a9507 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -125,7 +125,7 @@ jobs:
       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} ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicc -DCMAKE_CXX_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # Run cmake
     - name: echo cmake line

From c25cac80d5df18557eb9f71882a2a3c3c12eea7c Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 6 Jan 2026 10:29:37 +0100
Subject: [PATCH 57/99] Add openmpi to path [run ci]

---
 .../test_t8code_w_clang_and_ompi.yml          | 22 +++++++++----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 869f7a9507..c7630db294 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -75,17 +75,17 @@ jobs:
       run: clang --version
     - name: Verify gcc is absent
       run: ! command -v gcc
-    # - name: Export Clang compiler flags (not all strictly required, but safety first)
-    #   run: |
-    #     export CC=clang
-    #     export CXX=clang++
-    #     export MPICC=${OMPI_INSTALL_PATH}/bin/mpicc
-    #     export MPICXX=${OMPI_INSTALL_PATH}/bin/mpicxx
-    #     echo CC="$CC" >> $GITHUB_ENV
-    #     echo CXX="$CXX" >> $GITHUB_ENV
-    #     echo MPICC="$MPICC" >> $GITHUB_ENV
-    #     echo MPICXX="$MPICXX" >> $GITHUB_ENV
-    #     echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
+    - name: Export Clang compiler flags (not all strictly required, but safety first)
+      run: |
+        echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
+      #     export CC=clang
+      #     export CXX=clang++
+      #     export MPICC=${OMPI_INSTALL_PATH}/bin/mpicc
+      #     export MPICXX=${OMPI_INSTALL_PATH}/bin/mpicxx
+      #     echo CC="$CC" >> $GITHUB_ENV
+      #     echo CXX="$CXX" >> $GITHUB_ENV
+      #     echo MPICC="$MPICC" >> $GITHUB_ENV
+      #     echo MPICXX="$MPICXX" >> $GITHUB_ENV
     - name: Make sure MPI was built with CLANG
       # Note: If "clang" is not found, the workflow is exited (due to fail-early mode)
       run: |

From 5d62e2c394b58bb5e5a62645e3a93cb9a4d8e6b6 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 6 Jan 2026 10:33:25 +0100
Subject: [PATCH 58/99] Test more stuff [run ci]

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index c7630db294..e5ff8daca1 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -74,7 +74,8 @@ jobs:
     - name: Check Clang version
       run: clang --version
     - name: Verify gcc is absent
-      run: ! command -v gcc
+      run: |
+        which gcc
     - name: Export Clang compiler flags (not all strictly required, but safety first)
       run: |
         echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
@@ -95,8 +96,8 @@ jobs:
         rm mpi_version_output
     - name: Assert correct MPI paths
       run: |
-        mpicc --showme:compile | grep -q "${OMPI_INSTALL_PATH}"
-        mpicc --showme:link    | grep -q "${OMPI_INSTALL_PATH}"
+        mpicc --showme:compile | grep "${OMPI_INSTALL_PATH}"
+        mpicc --showme:link    | grep "${OMPI_INSTALL_PATH}"
     # - name: Make sure the right MPI path is used
     #   run: |
     #     which mpicc > which_mpi_output
@@ -125,7 +126,7 @@ jobs:
       run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
     - name: build config variables
-      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicc -DCMAKE_CXX_COMPILER=${OMPI_INSTALL_PATH}/bin/mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # Run cmake
     - name: echo cmake line

From 2c838fc0d5f5ee060eeccee221e41310eee04e4d Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 6 Jan 2026 11:02:18 +0100
Subject: [PATCH 59/99] Use updated docker image [run ci]

---
 .../test_t8code_w_clang_and_ompi.yml          | 24 +++++++++----------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index e5ff8daca1..333fbb5673 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -75,18 +75,18 @@ jobs:
       run: clang --version
     - name: Verify gcc is absent
       run: |
-        which gcc
-    - name: Export Clang compiler flags (not all strictly required, but safety first)
-      run: |
-        echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
-      #     export CC=clang
-      #     export CXX=clang++
-      #     export MPICC=${OMPI_INSTALL_PATH}/bin/mpicc
-      #     export MPICXX=${OMPI_INSTALL_PATH}/bin/mpicxx
-      #     echo CC="$CC" >> $GITHUB_ENV
-      #     echo CXX="$CXX" >> $GITHUB_ENV
-      #     echo MPICC="$MPICC" >> $GITHUB_ENV
-      #     echo MPICXX="$MPICXX" >> $GITHUB_ENV
+        ! command -v gcc
+    # - name: Export Clang compiler flags (not all strictly required, but safety first)
+    #   run: |
+    #     echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
+    #   #     export CC=clang
+    #   #     export CXX=clang++
+    #   #     export MPICC=${OMPI_INSTALL_PATH}/bin/mpicc
+    #   #     export MPICXX=${OMPI_INSTALL_PATH}/bin/mpicxx
+    #   #     echo CC="$CC" >> $GITHUB_ENV
+    #   #     echo CXX="$CXX" >> $GITHUB_ENV
+    #   #     echo MPICC="$MPICC" >> $GITHUB_ENV
+    #   #     echo MPICXX="$MPICXX" >> $GITHUB_ENV
     - name: Make sure MPI was built with CLANG
       # Note: If "clang" is not found, the workflow is exited (due to fail-early mode)
       run: |

From 653c9c67f070c57f8f6891147781f914f6f671d6 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 6 Jan 2026 11:14:31 +0100
Subject: [PATCH 60/99] Try exporting paths [run ci]

---
 .../test_t8code_w_clang_and_ompi.yml          | 22 +++++++++----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 333fbb5673..da39615616 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -76,17 +76,17 @@ jobs:
     - name: Verify gcc is absent
       run: |
         ! command -v gcc
-    # - name: Export Clang compiler flags (not all strictly required, but safety first)
-    #   run: |
-    #     echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
-    #   #     export CC=clang
-    #   #     export CXX=clang++
-    #   #     export MPICC=${OMPI_INSTALL_PATH}/bin/mpicc
-    #   #     export MPICXX=${OMPI_INSTALL_PATH}/bin/mpicxx
-    #   #     echo CC="$CC" >> $GITHUB_ENV
-    #   #     echo CXX="$CXX" >> $GITHUB_ENV
-    #   #     echo MPICC="$MPICC" >> $GITHUB_ENV
-    #   #     echo MPICXX="$MPICXX" >> $GITHUB_ENV
+    - name: Export Clang compiler flags (not all strictly required, but safety first)
+      run: |
+        export CC=clang
+        export CXX=clang++
+        export MPICC=${OMPI_INSTALL_PATH}/bin/mpicc
+        export MPICXX=${OMPI_INSTALL_PATH}/bin/mpicxx
+        echo CC="$CC" >> $GITHUB_ENV
+        echo CXX="$CXX" >> $GITHUB_ENV
+        echo MPICC="$MPICC" >> $GITHUB_ENV
+        echo MPICXX="$MPICXX" >> $GITHUB_ENV
+        # echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
     - name: Make sure MPI was built with CLANG
       # Note: If "clang" is not found, the workflow is exited (due to fail-early mode)
       run: |

From e188a83a2033b8177267d62f868a4f10290aec00 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 6 Jan 2026 11:23:08 +0100
Subject: [PATCH 61/99] Install ggc between build and testing to make gtests
 work (hopefully) [run ci]

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index da39615616..d0eaee37ab 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -148,6 +148,19 @@ jobs:
   #
   # Part 3: Run t8code tests
   # ------------------------
+    - name: Install gcc to make GoogleTests work.
+      run: apt-get update && apt-get install -y gcc g++
+    - name: Make sure MPI was built with CLANG
+      # Note: If "clang" is not found, 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
+        rm mpi_version_output
+    - name: Assert correct MPI paths
+      run: |
+        mpicc --showme:compile | grep "${OMPI_INSTALL_PATH}"
+        mpicc --showme:link    | grep "${OMPI_INSTALL_PATH}"
     # Run serial and parallel tests.
     - name: serial tests (if MPI is enabled)
       run: cd build && ctest $MAKEFLAGS -R _serial

From f19b8af9c6d756da090d5dcecbec945e135019ff Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 6 Jan 2026 11:40:35 +0100
Subject: [PATCH 62/99] Adjust to latest version of docker image [run ci]

---
 .../test_t8code_w_clang_and_ompi.yml          | 41 ++-----------------
 1 file changed, 4 insertions(+), 37 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index d0eaee37ab..2e8219ed55 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -64,8 +64,8 @@ jobs:
     container: dlramr/t8code-ubuntu:t8-clang-dependencies
     steps:
   #
-  # Part 1: Preparation
-  # -------------------
+  # Part 1: Preparation and sanity checks
+  # -------------------------------------
     - uses: actions/checkout@v6
       with:
         fetch-depth: 0
@@ -73,37 +73,18 @@ jobs:
       run: apt-get update && apt-get upgrade -y
     - name: Check Clang version
       run: clang --version
-    - name: Verify gcc is absent
-      run: |
-        ! command -v gcc
-    - name: Export Clang compiler flags (not all strictly required, but safety first)
-      run: |
-        export CC=clang
-        export CXX=clang++
-        export MPICC=${OMPI_INSTALL_PATH}/bin/mpicc
-        export MPICXX=${OMPI_INSTALL_PATH}/bin/mpicxx
-        echo CC="$CC" >> $GITHUB_ENV
-        echo CXX="$CXX" >> $GITHUB_ENV
-        echo MPICC="$MPICC" >> $GITHUB_ENV
-        echo MPICXX="$MPICXX" >> $GITHUB_ENV
-        # echo "${OMPI_INSTALL_PATH}/bin" >> $GITHUB_PATH
     - name: Make sure MPI was built with CLANG
-      # Note: If "clang" is not found, the workflow is exited (due to fail-early mode)
+      # Note: If "clang" is not found (or "gcc" is), the workflow is exited due to fail-early mode
       run: |
         mpicc --version > mpi_version_output
         cat mpi_version_output
         grep -i "clang" mpi_version_output
+        ! grep -i "gcc" mpi_version_output
         rm mpi_version_output
     - name: Assert correct MPI paths
       run: |
         mpicc --showme:compile | grep "${OMPI_INSTALL_PATH}"
         mpicc --showme:link    | grep "${OMPI_INSTALL_PATH}"
-    # - name: Make sure the right MPI path is used
-    #   run: |
-    #     which mpicc > which_mpi_output
-    #     cat which_mpi_output
-    #     grep -i "${OMPI_INSTALL_PATH}" which_mpi_output
-    #     rm which_mpi_output
       # This seems to be necessary because of the docker container
     - name: disable ownership checks
       run: git config --global --add safe.directory '*'
@@ -148,20 +129,6 @@ jobs:
   #
   # Part 3: Run t8code tests
   # ------------------------
-    - name: Install gcc to make GoogleTests work.
-      run: apt-get update && apt-get install -y gcc g++
-    - name: Make sure MPI was built with CLANG
-      # Note: If "clang" is not found, 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
-        rm mpi_version_output
-    - name: Assert correct MPI paths
-      run: |
-        mpicc --showme:compile | grep "${OMPI_INSTALL_PATH}"
-        mpicc --showme:link    | grep "${OMPI_INSTALL_PATH}"
-    # Run serial and parallel tests.
     - name: serial tests (if MPI is enabled)
       run: cd build && ctest $MAKEFLAGS -R _serial
       if: ${{ inputs.MPI == 'ON' }}

From 1e4593c7fa5c6dcfce181b7ff1751f19dc20c6af Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Tue, 6 Jan 2026 12:10:09 +0100
Subject: [PATCH 63/99] Reactivate other CI workflows

---
 .../test_t8code_w_clang_and_ompi.yml          |  10 +-
 .github/workflows/testsuite.yml               | 240 +++++++++---------
 2 files changed, 127 insertions(+), 123 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 2e8219ed55..9909e2acfe 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -71,7 +71,7 @@ jobs:
         fetch-depth: 0
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
-    - name: Check Clang version
+    - 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
@@ -81,10 +81,14 @@ jobs:
         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}"
+        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 '*'
diff --git a/.github/workflows/testsuite.yml b/.github/workflows/testsuite.yml
index 41ecdd5eb1..a7c1c1f5ac 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -105,124 +105,124 @@ jobs:
           exit 0
         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 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 }}
 
-  # # 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:
-  #     MAKEFLAGS: -j4
-  #     MPI: ON
-  #     BUILD_TYPE: Debug
-  #     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:
+      MAKEFLAGS: -j4
+      MPI: ON
+      BUILD_TYPE: Debug
+      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.
@@ -245,12 +245,12 @@ 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.
 
-  # # 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.
+  # 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.

From e1cea224a03fa73d60b98787dfe4fab80d2fa249 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 08:12:33 +0100
Subject: [PATCH 64/99] Try building Clang version with VTK

---
 .../test_t8code_w_clang_and_ompi.yml          |   2 +-
 .github/workflows/testsuite.yml               | 238 +++++++++---------
 2 files changed, 120 insertions(+), 120 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 9909e2acfe..a7498bca9e 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -111,7 +111,7 @@ jobs:
       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 ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=${VTK_INSTALL_PATH}/lib/cmake/vtk-9.1 -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_NETCDF=OFF""
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # Run cmake
     - name: echo cmake line
diff --git a/.github/workflows/testsuite.yml b/.github/workflows/testsuite.yml
index a7c1c1f5ac..55a9552d9a 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -105,124 +105,124 @@ jobs:
           exit 0
         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 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 }}
 
-  # 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:
-      MAKEFLAGS: -j4
-      MPI: ON
-      BUILD_TYPE: Debug
-      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:
+  #     MAKEFLAGS: -j4
+  #     MPI: ON
+  #     BUILD_TYPE: Debug
+  #     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.
@@ -245,12 +245,12 @@ 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.
 
-  # 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 6a542c67944ec482188f6f61f891612c455b9f19 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 08:49:45 +0100
Subject: [PATCH 65/99] Fix typo

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index a7498bca9e..da6a4236ab 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -111,7 +111,7 @@ jobs:
       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 ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=${VTK_INSTALL_PATH}/lib/cmake/vtk-9.1 -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_NETCDF=OFF""
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=${VTK_INSTALL_PATH}/lib/cmake/vtk-9.1 -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_NETCDF=OFF"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # Run cmake
     - name: echo cmake line

From 3657afc0d060da5059626d3c1da5bbb8f752a96b Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 09:08:05 +0100
Subject: [PATCH 66/99] Try without vtk

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index da6a4236ab..9a3ead70fc 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -111,8 +111,9 @@ jobs:
       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 ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=${VTK_INSTALL_PATH}/lib/cmake/vtk-9.1 -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_NETCDF=OFF"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
+    #run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=${VTK_INSTALL_PATH}/lib/cmake/vtk-9.1 -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_NETCDF=OFF"
     # Run cmake
     - name: echo cmake line
       run: echo cmake ../ $CONFIG_OPTIONS

From 90886df59d377bdcb2d60f33ad06fab7a5ec7ddc Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 09:27:11 +0100
Subject: [PATCH 67/99] Test with OCC

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 9a3ead70fc..32bf5aa4b5 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -111,7 +111,7 @@ jobs:
       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 ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     #run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=${VTK_INSTALL_PATH}/lib/cmake/vtk-9.1 -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_NETCDF=OFF"
     # Run cmake

From 1984de2cfef9043f38832074e2fbef722db15589 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 09:38:55 +0100
Subject: [PATCH 68/99] Try DCMAKE_PREFIX_PATH

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 32bf5aa4b5..990b36bf9c 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -110,8 +110,10 @@ 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: Try to make OCC findable
+      run: $OCCT_INSTALL_PATH
     - name: build config variables
-      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
+      run: export CONFIG_OPTIONS="-DCMAKE_PREFIX_PATH=${OCCT_INSTALL_PATH} -DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     #run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=${VTK_INSTALL_PATH}/lib/cmake/vtk-9.1 -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_NETCDF=OFF"
     # Run cmake

From e11b223d6c205c13b64e237b7b736ae74965bfda Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 09:50:13 +0100
Subject: [PATCH 69/99] Try again

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 990b36bf9c..3927c8a3c3 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -110,8 +110,8 @@ 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: Try to make OCC findable
-      run: $OCCT_INSTALL_PATH
+    # - name: Try to make OCC findable
+    #   run: $OCCT_INSTALL_PATH
     - name: build config variables
       run: export CONFIG_OPTIONS="-DCMAKE_PREFIX_PATH=${OCCT_INSTALL_PATH} -DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV

From 75c98445dc052bc426b4ba6254bf832b098c5797 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 09:58:40 +0100
Subject: [PATCH 70/99] Try again

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 3927c8a3c3..ffef6a78b8 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -113,14 +113,16 @@ jobs:
     # - name: Try to make OCC findable
     #   run: $OCCT_INSTALL_PATH
     - name: build config variables
-      run: export CONFIG_OPTIONS="-DCMAKE_PREFIX_PATH=${OCCT_INSTALL_PATH} -DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     #run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=${VTK_INSTALL_PATH}/lib/cmake/vtk-9.1 -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_NETCDF=OFF"
     # Run cmake
     - name: echo cmake line
       run: echo cmake ../ $CONFIG_OPTIONS
     - name: cmake
-      run: mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
+      run: |
+        export CASROOT=${OCCT_INSTALL_PATH}
+        mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
     # On failure, upload logs
     - name: OnFailUploadLog
       if: failure()

From e2de5f551a9aa4c5f571a9122a0295524aa503ca Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 10:18:50 +0100
Subject: [PATCH 71/99] Try simlink

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index ffef6a78b8..1bb87e0686 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -110,8 +110,8 @@ 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: Try to make OCC findable
-    #   run: $OCCT_INSTALL_PATH
+    - name: Try to make OCC findable
+      run: sudo ln -s $OCCT_INSTALL_PATH/inc /opt/occ/inc 
     - name: build config variables
       run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
@@ -121,8 +121,9 @@ jobs:
       run: echo cmake ../ $CONFIG_OPTIONS
     - name: cmake
       run: |
-        export CASROOT=${OCCT_INSTALL_PATH}
         mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
+    # export CASROOT=${OCCT_INSTALL_PATH}
+    # echo "CASROOT=$CASROOT"
     # On failure, upload logs
     - name: OnFailUploadLog
       if: failure()

From c90e078aa9f3423dea7d4f6df7e6add5f7d62236 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 10:24:54 +0100
Subject: [PATCH 72/99] Try simlink again

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 1bb87e0686..118d8855fb 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -111,7 +111,9 @@ jobs:
       run: export TEST_LEVEL_FLAG="-DT8CODE_TEST_LEVEL=${{ inputs.TEST_LEVEL }}"
            && echo TEST_LEVEL_FLAG="$TEST_LEVEL_FLAG" >> $GITHUB_ENV
     - name: Try to make OCC findable
-      run: sudo ln -s $OCCT_INSTALL_PATH/inc /opt/occ/inc 
+      run: |
+        sudo mkdir -p /opt/occ
+        sudo ln -s $OCCT_INSTALL_PATH/inc /opt/occ/inc 
     - name: build config variables
       run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV

From da6735a902411d80a39aba4853400910288c16d7 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 10:28:04 +0100
Subject: [PATCH 73/99] Try simlink again

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 118d8855fb..cb4bfdc4f3 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -114,6 +114,7 @@ jobs:
       run: |
         sudo mkdir -p /opt/occ
         sudo ln -s $OCCT_INSTALL_PATH/inc /opt/occ/inc 
+        ls /opt/occ/inc
     - name: build config variables
       run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV

From 668725e8ed9287f8bf840c2c46b079827fc1a218 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 10:29:46 +0100
Subject: [PATCH 74/99] Peek into OCCT folder

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index cb4bfdc4f3..a65c0c2ab4 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -110,6 +110,10 @@ 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: Peek into OCCT folder
+      run: |
+        cd $OCCT_INSTALL_PATH
+        ls * */* */*/*
     - name: Try to make OCC findable
       run: |
         sudo mkdir -p /opt/occ

From d17ad73692b0bcbe97cfe54b2d81444768685a5e Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 10:41:27 +0100
Subject: [PATCH 75/99] Link include into inc

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index a65c0c2ab4..e1b820ead1 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -116,9 +116,7 @@ jobs:
         ls * */* */*/*
     - name: Try to make OCC findable
       run: |
-        sudo mkdir -p /opt/occ
-        sudo ln -s $OCCT_INSTALL_PATH/inc /opt/occ/inc 
-        ls /opt/occ/inc
+        ln -s $OCCT_INSTALL_PATH/include $OCCT_INSTALL_PATH/inc
     - name: build config variables
       run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
@@ -128,9 +126,9 @@ jobs:
       run: echo cmake ../ $CONFIG_OPTIONS
     - name: cmake
       run: |
+        export CASROOT=${OCCT_INSTALL_PATH}
+        echo "CASROOT=$CASROOT"
         mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
-    # export CASROOT=${OCCT_INSTALL_PATH}
-    # echo "CASROOT=$CASROOT"
     # On failure, upload logs
     - name: OnFailUploadLog
       if: failure()

From 26d46a1d4325473dc90daa70f4c7840fb0f61151 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 10:45:39 +0100
Subject: [PATCH 76/99] Try more

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index e1b820ead1..4d8a5cd831 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -117,6 +117,8 @@ jobs:
     - name: Try to make OCC findable
       run: |
         ln -s $OCCT_INSTALL_PATH/include $OCCT_INSTALL_PATH/inc
+        mkdir -p  /opt/occ
+        ln -sf $OCCT_INSTALL_PATH/inc /opt/occ/inc
     - name: build config variables
       run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV

From a6221813a7075149ea3e4ad70eee35c5d306234e Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 10:46:31 +0100
Subject: [PATCH 77/99] Add sudo

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 4d8a5cd831..727609dba5 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -117,8 +117,12 @@ jobs:
     - name: Try to make OCC findable
       run: |
         ln -s $OCCT_INSTALL_PATH/include $OCCT_INSTALL_PATH/inc
-        mkdir -p  /opt/occ
-        ln -sf $OCCT_INSTALL_PATH/inc /opt/occ/inc
+        sudo mkdir -p  /opt/occ
+        sudo ln -sf $OCCT_INSTALL_PATH/inc /opt/occ/inc
+        echo "/opt/occ/inc contains"
+        ls /opt/occ/inc
+        echo "$OCCT_INSTALL_PATH/inc contains"
+        ls $OCCT_INSTALL_PATH/inc
     - name: build config variables
       run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV

From e89d2ece00f808f258af5ea7e05dea0f771da7d6 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 10:54:25 +0100
Subject: [PATCH 78/99] Start messing with FindOpenCASCADE.cmake

---
 cmake/FindOpenCASCADE.cmake | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cmake/FindOpenCASCADE.cmake b/cmake/FindOpenCASCADE.cmake
index 6eb5c10c22..dc617f2c5b 100644
--- a/cmake/FindOpenCASCADE.cmake
+++ b/cmake/FindOpenCASCADE.cmake
@@ -34,7 +34,7 @@ IF( NOT OpenCASCADE_FOUND )
     ENDIF( CMAKE_SIZEOF_VOID_P EQUAL 4 )
 
   IF(UNIX)
-    set( _incsearchpath /usr/include/opencascade;/usr/include/;/opt/occ/inc;${CASROOT}/inc;${CASROOT}/include/ )
+    set( _incsearchpath /usr/include/opencascade;/usr/include/;/opt/occ/inc;${CASROOT}/inc;${CASROOT}/include/;${CASROOT}/inc/opencascade/;${CASROOT}/include/opencascade/ )
     set( _libsearchpath /usr/lib64;/usr/lib;/opt/occ/lib;${CASROOT}/lib64;${CASROOT}/lib )
   ELSE(UNIX)
     IF (WIN32)

From 8277f12b582bc6a78bcc8577850f244bd09cf43e Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 11:03:05 +0100
Subject: [PATCH 79/99] Set CASROOT for build step too

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 727609dba5..ac404fa0ab 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -144,9 +144,13 @@ jobs:
         path: build/CMakeFiles/CMakeOutput.log
     # Build with ninja
     - name: ninja
-      run: cd build && ninja $MAKEFLAGS
+      run: |
+        export CASROOT=${OCCT_INSTALL_PATH}
+        cd build && ninja $MAKEFLAGS
     - name: ninja install
-      run: cd build && ninja install $MAKEFLAGS
+      run: |
+        export CASROOT=${OCCT_INSTALL_PATH}
+        cd build && ninja install $MAKEFLAGS
   #
   # Part 3: Run t8code tests
   # ------------------------

From bf8a388984001a93352e72a41d207312bc17ccf4 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 11:14:00 +0100
Subject: [PATCH 80/99] Try adding Standard_Handle.hxx

---
 src/t8_cad/t8_cad.hxx | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/t8_cad/t8_cad.hxx b/src/t8_cad/t8_cad.hxx
index 82ddf19593..0047893c97 100644
--- a/src/t8_cad/t8_cad.hxx
+++ b/src/t8_cad/t8_cad.hxx
@@ -32,6 +32,7 @@
 #include <TopExp.hxx>
 #include <Geom_Surface.hxx>
 #include <Geom_Curve.hxx>
+#include <Standard_Handle.hxx>
 
 /**
  * This class manages OpenCASCADE shapes and implements helper functions for working with the shapes.

From c6107422768657e28f4294f7fb9429a33fb1c370 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 12:23:10 +0100
Subject: [PATCH 81/99] Try adding Standard_Handle.hxx before other headers

---
 src/t8_cad/t8_cad.hxx | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/t8_cad/t8_cad.hxx b/src/t8_cad/t8_cad.hxx
index 0047893c97..d5c75e5bd4 100644
--- a/src/t8_cad/t8_cad.hxx
+++ b/src/t8_cad/t8_cad.hxx
@@ -28,11 +28,11 @@
 #ifndef T8_CAD_HXX
 #define T8_CAD_HXX
 
+#include <Standard_Handle.hxx>
 #include <gp_Pnt.hxx>
 #include <TopExp.hxx>
 #include <Geom_Surface.hxx>
 #include <Geom_Curve.hxx>
-#include <Standard_Handle.hxx>
 
 /**
  * This class manages OpenCASCADE shapes and implements helper functions for working with the shapes.

From 8bbe13690b6add3b110eb90286bbfb4f21dd1ed0 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 12:30:03 +0100
Subject: [PATCH 82/99] Try uploading docker image

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index ac404fa0ab..b93927f597 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -69,6 +69,14 @@ jobs:
     - uses: actions/checkout@v6
       with:
         fetch-depth: 0
+  #
+    - name: Save docker image
+      run: docker save dlramr/t8code-ubuntu:t8-clang-dependencies -o t8code-clang.tar
+    - name: Upload artifact
+      uses: actions/upload-artifact@v5
+      with:
+        name: t8code-image
+        path: t8code-clang.tar
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
     - name: Show Clang version

From 35b9b3e7a1d5cb1837dc2dac9ddabea00d0917f5 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 12:33:25 +0100
Subject: [PATCH 83/99] Add more standrad_handle

---
 src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.cxx | 1 +
 src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.hxx | 1 +
 2 files changed, 2 insertions(+)

diff --git a/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.cxx b/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.cxx
index 158c112c04..3c614d28c6 100644
--- a/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.cxx
+++ b/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.cxx
@@ -25,6 +25,7 @@
  *  or the C interface \ref t8_geometry_cad.h.
  */
 
+#include <Standard_Handle.hxx>
 #include <t8.h>
 #include <t8_geometry/t8_geometry_implementations/t8_geometry_cad.hxx>
 #include <t8_geometry/t8_geometry_implementations/t8_geometry_cad.h>
diff --git a/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.hxx b/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.hxx
index d81e1a0454..7379faae55 100644
--- a/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.hxx
+++ b/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.hxx
@@ -29,6 +29,7 @@
 #ifndef T8_GEOMETRY_CAD_HXX
 #define T8_GEOMETRY_CAD_HXX
 
+#include <Standard_Handle.hxx>
 #include <t8.h>
 #include <t8_geometry/t8_geometry_with_vertices.hxx>
 #include <t8_cmesh/t8_cmesh_internal/t8_cmesh_types.h>

From d3b91d735f1a7fa03354954d3a7c0a6f7998d500 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 12:36:17 +0100
Subject: [PATCH 84/99] Try saving image

---
 .../test_t8code_w_clang_and_ompi.yml          | 23 ++++++++++++-------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index b93927f597..237d9828a0 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -54,6 +54,21 @@ on:
         default: 'T8_TEST_LEVEL_FULL'
 
 jobs:
+  save-image:
+    runs-on: ubuntu-latest   # runs on a VM with Docker
+    steps:
+      - name: Pull image
+        run: docker pull dlramr/t8code-ubuntu:t8-clang-dependencies
+
+      - name: Save image as tarball
+        run: docker save dlramr/t8code-ubuntu:t8-clang-dependencies -o t8code-clang.tar
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v3
+        with:
+          name: t8code-image
+          path: t8code-clang.tar
+
   t8code_cmake_tests:
   #
   # Container setup: To avoid unwanted side effects of gcc or mpich, an own Clang version of the
@@ -69,14 +84,6 @@ jobs:
     - uses: actions/checkout@v6
       with:
         fetch-depth: 0
-  #
-    - name: Save docker image
-      run: docker save dlramr/t8code-ubuntu:t8-clang-dependencies -o t8code-clang.tar
-    - name: Upload artifact
-      uses: actions/upload-artifact@v5
-      with:
-        name: t8code-image
-        path: t8code-clang.tar
     - name: Update packages
       run: apt-get update && apt-get upgrade -y
     - name: Show Clang version

From 1eee9a437d294715e821221e6c4a6a28a2ae711d Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 12:40:29 +0100
Subject: [PATCH 85/99] Try again

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 237d9828a0..949a59ca10 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -64,7 +64,7 @@ jobs:
         run: docker save dlramr/t8code-ubuntu:t8-clang-dependencies -o t8code-clang.tar
 
       - name: Upload artifact
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v5
         with:
           name: t8code-image
           path: t8code-clang.tar

From a3d61ac0f1d76086edfea9c4b2b6a5e83ef81635 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 13:48:52 +0100
Subject: [PATCH 86/99] Check opencascade version

---
 .github/workflows/test_t8code_linkage.yml |  2 +
 .github/workflows/testsuite.yml           | 56 +++++++++++------------
 2 files changed, 30 insertions(+), 28 deletions(-)

diff --git a/.github/workflows/test_t8code_linkage.yml b/.github/workflows/test_t8code_linkage.yml
index f6e2a20bf0..7e2c5f51cf 100644
--- a/.github/workflows/test_t8code_linkage.yml
+++ b/.github/workflows/test_t8code_linkage.yml
@@ -122,6 +122,8 @@ jobs:
 # cmake and test with OpenCASCADE
     - name: check OpenCASCADE
       run: echo "Checking OpenCASCADE"
+    - name: Show OpenCASCADE version
+      run: dpkg -l | grep opencascade
     - name: echo cmake line
       run: echo cmake ../ $CONFIG_OPTIONS -DT8CODE_ENABLE_OCC=ON
     - name: cmake OpenCASCADE
diff --git a/.github/workflows/testsuite.yml b/.github/workflows/testsuite.yml
index 210be5ff40..acd5dfe6f1 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -105,23 +105,23 @@ jobs:
           exit 0
         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 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 }}
 
   # # Run parallel tests for sc and p4est with and without MPI
   # sc_p4est_tests:
@@ -154,17 +154,17 @@ 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.
 
-  # # 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
+  # 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 }}

From fac405651c490c878cf10f0576f8417760df88b7 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Thu, 15 Jan 2026 13:57:42 +0100
Subject: [PATCH 87/99] Check opencascade version

---
 .github/workflows/testsuite.yml | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/testsuite.yml b/.github/workflows/testsuite.yml
index acd5dfe6f1..2471e472af 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -165,11 +165,11 @@ jobs:
         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.
+    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:

From 750213354a4016d9deccc047c2c685cb4628536d Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 16 Jan 2026 09:04:19 +0100
Subject: [PATCH 88/99] Try once again without external libraries

---
 .../test_t8code_w_clang_and_ompi.yml          | 28 +++++++++----------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 949a59ca10..228f259c19 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -125,21 +125,21 @@ 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: Peek into OCCT folder
-      run: |
-        cd $OCCT_INSTALL_PATH
-        ls * */* */*/*
-    - name: Try to make OCC findable
-      run: |
-        ln -s $OCCT_INSTALL_PATH/include $OCCT_INSTALL_PATH/inc
-        sudo mkdir -p  /opt/occ
-        sudo ln -sf $OCCT_INSTALL_PATH/inc /opt/occ/inc
-        echo "/opt/occ/inc contains"
-        ls /opt/occ/inc
-        echo "$OCCT_INSTALL_PATH/inc contains"
-        ls $OCCT_INSTALL_PATH/inc
+    # - name: Peek into OCCT folder
+    #   run: |
+    #     cd $OCCT_INSTALL_PATH
+    #     ls * */* */*/*
+    # - name: Try to make OCC findable
+    #   run: |
+    #     ln -s $OCCT_INSTALL_PATH/include $OCCT_INSTALL_PATH/inc
+    #     sudo mkdir -p  /opt/occ
+    #     sudo ln -sf $OCCT_INSTALL_PATH/inc /opt/occ/inc
+    #     echo "/opt/occ/inc contains"
+    #     ls /opt/occ/inc
+    #     echo "$OCCT_INSTALL_PATH/inc contains"
+    #     ls $OCCT_INSTALL_PATH/inc
     - name: build config variables
-      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=OFF"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     #run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=${VTK_INSTALL_PATH}/lib/cmake/vtk-9.1 -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_NETCDF=OFF"
     # Run cmake

From d73f5dba8c1fb71ece310395f1abb8f8884f2567 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 16 Jan 2026 09:14:55 +0100
Subject: [PATCH 89/99] Try with OCC again

---
 .../test_t8code_w_clang_and_ompi.yml          | 44 ++++++-------
 .github/workflows/testsuite.yml               | 66 +++++++++----------
 2 files changed, 55 insertions(+), 55 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 228f259c19..dc97a7f1a7 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -54,20 +54,20 @@ on:
         default: 'T8_TEST_LEVEL_FULL'
 
 jobs:
-  save-image:
-    runs-on: ubuntu-latest   # runs on a VM with Docker
-    steps:
-      - name: Pull image
-        run: docker pull dlramr/t8code-ubuntu:t8-clang-dependencies
+  # save-image:
+  #   runs-on: ubuntu-latest   # runs on a VM with Docker
+  #   steps:
+  #     - name: Pull image
+  #       run: docker pull dlramr/t8code-ubuntu:t8-clang-dependencies
 
-      - name: Save image as tarball
-        run: docker save dlramr/t8code-ubuntu:t8-clang-dependencies -o t8code-clang.tar
+  #     - name: Save image as tarball
+  #       run: docker save dlramr/t8code-ubuntu:t8-clang-dependencies -o t8code-clang.tar
 
-      - name: Upload artifact
-        uses: actions/upload-artifact@v5
-        with:
-          name: t8code-image
-          path: t8code-clang.tar
+  #     - name: Upload artifact
+  #       uses: actions/upload-artifact@v5
+  #       with:
+  #         name: t8code-image
+  #         path: t8code-clang.tar
 
   t8code_cmake_tests:
   #
@@ -129,17 +129,17 @@ jobs:
     #   run: |
     #     cd $OCCT_INSTALL_PATH
     #     ls * */* */*/*
-    # - name: Try to make OCC findable
-    #   run: |
-    #     ln -s $OCCT_INSTALL_PATH/include $OCCT_INSTALL_PATH/inc
-    #     sudo mkdir -p  /opt/occ
-    #     sudo ln -sf $OCCT_INSTALL_PATH/inc /opt/occ/inc
-    #     echo "/opt/occ/inc contains"
-    #     ls /opt/occ/inc
-    #     echo "$OCCT_INSTALL_PATH/inc contains"
-    #     ls $OCCT_INSTALL_PATH/inc
+    - name: Try to make OCC findable
+      run: |
+        ln -s $OCCT_INSTALL_PATH/include $OCCT_INSTALL_PATH/inc
+        sudo mkdir -p  /opt/occ
+        sudo ln -sf $OCCT_INSTALL_PATH/inc /opt/occ/inc
+        echo "/opt/occ/inc contains"
+        ls /opt/occ/inc
+        echo "$OCCT_INSTALL_PATH/inc contains"
+        ls $OCCT_INSTALL_PATH/inc
     - name: build config variables
-      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=OFF"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     #run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=${VTK_INSTALL_PATH}/lib/cmake/vtk-9.1 -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_NETCDF=OFF"
     # Run cmake
diff --git a/.github/workflows/testsuite.yml b/.github/workflows/testsuite.yml
index 2471e472af..210be5ff40 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -105,23 +105,23 @@ jobs:
           exit 0
         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 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 }}
 
   # # Run parallel tests for sc and p4est with and without MPI
   # sc_p4est_tests:
@@ -154,22 +154,22 @@ 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.
 
-  # 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:

From 43d32044f6933759f21fffe98a762a51106581bb Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 16 Jan 2026 09:48:28 +0100
Subject: [PATCH 90/99] Set LD_LIBRARY_PATH

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index dc97a7f1a7..be1bf9ec0c 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -138,10 +138,13 @@ jobs:
         ls /opt/occ/inc
         echo "$OCCT_INSTALL_PATH/inc contains"
         ls $OCCT_INSTALL_PATH/inc
+    - name: Adjust LD_LIBRARY_PATH (TODO Move to docker image)
+      run: |
+        export LD_LIBRARY_PATH=$OCCT_INSTALL_PATH/lib:$LD_LIBRARY_PATH
+        echo LD_LIBRARY_PATH="$LD_LIBRARY_PATH" >> $GITHUB_ENV
     - name: build config variables
       run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
-    #run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=${VTK_INSTALL_PATH}/lib/cmake/vtk-9.1 -DT8CODE_ENABLE_OCC=OFF -DT8CODE_ENABLE_NETCDF=OFF"
     # Run cmake
     - name: echo cmake line
       run: echo cmake ../ $CONFIG_OPTIONS

From 9b6c2e90892f578a8abc95829b7d8542e41adf53 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 16 Jan 2026 12:34:57 +0100
Subject: [PATCH 91/99] Try new docker image

---
 .../test_t8code_w_clang_and_ompi.yml          | 40 +++++++++----------
 1 file changed, 19 insertions(+), 21 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index be1bf9ec0c..1a5692faf0 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -76,7 +76,7 @@ jobs:
   #                  Clang version of OpenMPI.
     timeout-minutes: 60
     runs-on: ubuntu-latest
-    container: dlramr/t8code-ubuntu:t8-clang-dependencies
+    container: dlramr/t8code-ubuntu:t8-clanglight-dependencies
     steps:
   #
   # Part 1: Preparation and sanity checks
@@ -128,31 +128,31 @@ jobs:
     # - name: Peek into OCCT folder
     #   run: |
     #     cd $OCCT_INSTALL_PATH
-    #     ls * */* */*/*
-    - name: Try to make OCC findable
-      run: |
-        ln -s $OCCT_INSTALL_PATH/include $OCCT_INSTALL_PATH/inc
-        sudo mkdir -p  /opt/occ
-        sudo ln -sf $OCCT_INSTALL_PATH/inc /opt/occ/inc
-        echo "/opt/occ/inc contains"
-        ls /opt/occ/inc
-        echo "$OCCT_INSTALL_PATH/inc contains"
-        ls $OCCT_INSTALL_PATH/inc
-    - name: Adjust LD_LIBRARY_PATH (TODO Move to docker image)
-      run: |
-        export LD_LIBRARY_PATH=$OCCT_INSTALL_PATH/lib:$LD_LIBRARY_PATH
-        echo LD_LIBRARY_PATH="$LD_LIBRARY_PATH" >> $GITHUB_ENV
+    # #     ls * */* */*/*
+    # - name: Try to make OCC findable
+    #   run: |
+    #     ln -s $OCCT_INSTALL_PATH/include $OCCT_INSTALL_PATH/inc
+    #     sudo mkdir -p  /opt/occ
+    #     sudo ln -sf $OCCT_INSTALL_PATH/inc /opt/occ/inc
+    #     echo "/opt/occ/inc contains"
+    #     ls /opt/occ/inc
+    #     echo "$OCCT_INSTALL_PATH/inc contains"
+    #     ls $OCCT_INSTALL_PATH/inc
+    # - name: Adjust LD_LIBRARY_PATH (TODO Move to docker image)
+    #   run: |
+    #     export LD_LIBRARY_PATH=$OCCT_INSTALL_PATH/lib:$LD_LIBRARY_PATH
+    #     echo LD_LIBRARY_PATH="$LD_LIBRARY_PATH" >> $GITHUB_ENV
     - name: build config variables
-      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_OCC=ON"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_NETCDF=ON -DT8CODE_ENABLE_OCC=ON"
         && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
     # Run cmake
     - name: echo cmake line
       run: echo cmake ../ $CONFIG_OPTIONS
     - name: cmake
       run: |
-        export CASROOT=${OCCT_INSTALL_PATH}
-        echo "CASROOT=$CASROOT"
-        mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
+         mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
+    # export CASROOT=${OCCT_INSTALL_PATH}
+    # echo "CASROOT=$CASROOT"
     # On failure, upload logs
     - name: OnFailUploadLog
       if: failure()
@@ -163,11 +163,9 @@ jobs:
     # Build with ninja
     - name: ninja
       run: |
-        export CASROOT=${OCCT_INSTALL_PATH}
         cd build && ninja $MAKEFLAGS
     - name: ninja install
       run: |
-        export CASROOT=${OCCT_INSTALL_PATH}
         cd build && ninja install $MAKEFLAGS
   #
   # Part 3: Run t8code tests

From 1f0d1cada15f8fd596b5bce0582014761ad226bb Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 16 Jan 2026 15:13:55 +0100
Subject: [PATCH 92/99] Move back to lighter clang docker container

---
 .github/workflows/test_t8code_linkage.yml     |  2 -
 .../test_t8code_w_clang_and_ompi.yml          | 47 ++-----------------
 cmake/FindOpenCASCADE.cmake                   |  2 +-
 src/t8_cad/t8_cad.hxx                         |  1 -
 .../t8_geometry_cad.cxx                       |  1 -
 .../t8_geometry_cad.hxx                       |  1 -
 6 files changed, 6 insertions(+), 48 deletions(-)

diff --git a/.github/workflows/test_t8code_linkage.yml b/.github/workflows/test_t8code_linkage.yml
index 7e2c5f51cf..f6e2a20bf0 100644
--- a/.github/workflows/test_t8code_linkage.yml
+++ b/.github/workflows/test_t8code_linkage.yml
@@ -122,8 +122,6 @@ jobs:
 # cmake and test with OpenCASCADE
     - name: check OpenCASCADE
       run: echo "Checking OpenCASCADE"
-    - name: Show OpenCASCADE version
-      run: dpkg -l | grep opencascade
     - name: echo cmake line
       run: echo cmake ../ $CONFIG_OPTIONS -DT8CODE_ENABLE_OCC=ON
     - name: cmake OpenCASCADE
diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 1a5692faf0..ba0a79636a 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -54,21 +54,6 @@ on:
         default: 'T8_TEST_LEVEL_FULL'
 
 jobs:
-  # save-image:
-  #   runs-on: ubuntu-latest   # runs on a VM with Docker
-  #   steps:
-  #     - name: Pull image
-  #       run: docker pull dlramr/t8code-ubuntu:t8-clang-dependencies
-
-  #     - name: Save image as tarball
-  #       run: docker save dlramr/t8code-ubuntu:t8-clang-dependencies -o t8code-clang.tar
-
-  #     - name: Upload artifact
-  #       uses: actions/upload-artifact@v5
-  #       with:
-  #         name: t8code-image
-  #         path: t8code-clang.tar
-
   t8code_cmake_tests:
   #
   # Container setup: To avoid unwanted side effects of gcc or mpich, an own Clang version of the
@@ -76,7 +61,7 @@ jobs:
   #                  Clang version of OpenMPI.
     timeout-minutes: 60
     runs-on: ubuntu-latest
-    container: dlramr/t8code-ubuntu:t8-clanglight-dependencies
+    container: dlramr/t8code-ubuntu:t8-clang-dependencies
     steps:
   #
   # Part 1: Preparation and sanity checks
@@ -125,34 +110,14 @@ 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: Peek into OCCT folder
-    #   run: |
-    #     cd $OCCT_INSTALL_PATH
-    # #     ls * */* */*/*
-    # - name: Try to make OCC findable
-    #   run: |
-    #     ln -s $OCCT_INSTALL_PATH/include $OCCT_INSTALL_PATH/inc
-    #     sudo mkdir -p  /opt/occ
-    #     sudo ln -sf $OCCT_INSTALL_PATH/inc /opt/occ/inc
-    #     echo "/opt/occ/inc contains"
-    #     ls /opt/occ/inc
-    #     echo "$OCCT_INSTALL_PATH/inc contains"
-    #     ls $OCCT_INSTALL_PATH/inc
-    # - name: Adjust LD_LIBRARY_PATH (TODO Move to docker image)
-    #   run: |
-    #     export LD_LIBRARY_PATH=$OCCT_INSTALL_PATH/lib:$LD_LIBRARY_PATH
-    #     echo LD_LIBRARY_PATH="$LD_LIBRARY_PATH" >> $GITHUB_ENV
     - name: build config variables
-      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_NETCDF=ON -DT8CODE_ENABLE_OCC=ON"
+      run: export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_NETCDF=ON -DT8CODE_ENABLE_OCC=ON -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=$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 ../ $CONFIG_OPTIONS
-    # export CASROOT=${OCCT_INSTALL_PATH}
-    # echo "CASROOT=$CASROOT"
+      run: mkdir build && cd build && cmake ../ $CONFIG_OPTIONS
     # On failure, upload logs
     - name: OnFailUploadLog
       if: failure()
@@ -162,11 +127,9 @@ jobs:
         path: build/CMakeFiles/CMakeOutput.log
     # Build with ninja
     - name: ninja
-      run: |
-        cd build && ninja $MAKEFLAGS
+      run: cd build && ninja $MAKEFLAGS
     - name: ninja install
-      run: |
-        cd build && ninja install $MAKEFLAGS
+      run: cd build && ninja install $MAKEFLAGS
   #
   # Part 3: Run t8code tests
   # ------------------------
diff --git a/cmake/FindOpenCASCADE.cmake b/cmake/FindOpenCASCADE.cmake
index dc617f2c5b..6eb5c10c22 100644
--- a/cmake/FindOpenCASCADE.cmake
+++ b/cmake/FindOpenCASCADE.cmake
@@ -34,7 +34,7 @@ IF( NOT OpenCASCADE_FOUND )
     ENDIF( CMAKE_SIZEOF_VOID_P EQUAL 4 )
 
   IF(UNIX)
-    set( _incsearchpath /usr/include/opencascade;/usr/include/;/opt/occ/inc;${CASROOT}/inc;${CASROOT}/include/;${CASROOT}/inc/opencascade/;${CASROOT}/include/opencascade/ )
+    set( _incsearchpath /usr/include/opencascade;/usr/include/;/opt/occ/inc;${CASROOT}/inc;${CASROOT}/include/ )
     set( _libsearchpath /usr/lib64;/usr/lib;/opt/occ/lib;${CASROOT}/lib64;${CASROOT}/lib )
   ELSE(UNIX)
     IF (WIN32)
diff --git a/src/t8_cad/t8_cad.hxx b/src/t8_cad/t8_cad.hxx
index d5c75e5bd4..82ddf19593 100644
--- a/src/t8_cad/t8_cad.hxx
+++ b/src/t8_cad/t8_cad.hxx
@@ -28,7 +28,6 @@
 #ifndef T8_CAD_HXX
 #define T8_CAD_HXX
 
-#include <Standard_Handle.hxx>
 #include <gp_Pnt.hxx>
 #include <TopExp.hxx>
 #include <Geom_Surface.hxx>
diff --git a/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.cxx b/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.cxx
index 3c614d28c6..158c112c04 100644
--- a/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.cxx
+++ b/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.cxx
@@ -25,7 +25,6 @@
  *  or the C interface \ref t8_geometry_cad.h.
  */
 
-#include <Standard_Handle.hxx>
 #include <t8.h>
 #include <t8_geometry/t8_geometry_implementations/t8_geometry_cad.hxx>
 #include <t8_geometry/t8_geometry_implementations/t8_geometry_cad.h>
diff --git a/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.hxx b/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.hxx
index 7379faae55..d81e1a0454 100644
--- a/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.hxx
+++ b/src/t8_geometry/t8_geometry_implementations/t8_geometry_cad.hxx
@@ -29,7 +29,6 @@
 #ifndef T8_GEOMETRY_CAD_HXX
 #define T8_GEOMETRY_CAD_HXX
 
-#include <Standard_Handle.hxx>
 #include <t8.h>
 #include <t8_geometry/t8_geometry_with_vertices.hxx>
 #include <t8_cmesh/t8_cmesh_internal/t8_cmesh_types.h>

From 85f6526e9f35331a833710e81d34348ce3ab53d0 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 16 Jan 2026 15:19:52 +0100
Subject: [PATCH 93/99] Extended a comment

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index ba0a79636a..01c3ca28d6 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -33,7 +33,7 @@ env:
 on:
   workflow_call:
     # Note: To simplify adding more configurations of this workflow later, the MPI mode and the BUILD_TYPE
-    #       are passed as input.
+    #       are passed as input, although currently only MPI on and Debug mode are tested.
     inputs:
       MAKEFLAGS:
         required: true

From a61555d7b02d7dbe3866a388e1552382e61aa264 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 16 Jan 2026 15:38:31 +0100
Subject: [PATCH 94/99] Reactivate gcc-based workflows

---
 .github/workflows/testsuite.yml | 267 ++++++++++++++------------------
 1 file changed, 116 insertions(+), 151 deletions(-)

diff --git a/.github/workflows/testsuite.yml b/.github/workflows/testsuite.yml
index 210be5ff40..b0c1ea7cc7 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -105,124 +105,121 @@ jobs:
           exit 0
         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 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 }}
 
-  # # 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:
-  #     MAKEFLAGS: -j4
-  #     MPI: ON
-  #     BUILD_TYPE: Debug
-  #     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.
@@ -245,44 +242,12 @@ 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.
 
-  # # Build doxygen documentation and check for errors / warnings.
-  # t8code_doxygen_check:
-  #   uses: ./.github/workflows/check_doxygen.yml
-  # 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 }}
-
-  # 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.
+  # 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 d1a4b7901d1215158d975a46e8a421669b6c234a Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 16 Jan 2026 15:42:07 +0100
Subject: [PATCH 95/99] Updated some descriptions

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 4 ++--
 .github/workflows/testsuite.yml                    | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 01c3ca28d6..0b51381597 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -24,8 +24,8 @@ name: CMake tests t8code with Clang compiler and OpenMPI
 #  This workflow checks whether building and testing works with the Clang compiler
 #  and openmpi. It was added because all of t8code's remaining CI workflows rely
 #  on gcc and mpich, hence missing Clang- or openmpi-specific issues.
-#  To reduce runtime, (for now) only Debug mode with MPI is tested; also, no external
-#  libraries like VTK, OpenCASCADE etc. are covered.
+#  To reduce runtime, (for now) only one configuration is run, that is, Debug mode
+#  with MPI and all external libraries (VTK, OpenCASCADE, NetCDF).
 
 env:
   DEBUG_CONFIG: "-O1"
diff --git a/.github/workflows/testsuite.yml b/.github/workflows/testsuite.yml
index b0c1ea7cc7..631f7f48e8 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -223,7 +223,7 @@ jobs:
 
   # 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 used Debug mode with MPI on and does not link to external libraries like VTK or OpenCASCADE.
+  #       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

From 13a3e5b0460bd8dadd421cb916762b1e12f4a7a4 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 16 Jan 2026 15:49:07 +0100
Subject: [PATCH 96/99] Make CONFIG_OPTIONS more readable

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 0b51381597..b66d05de54 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -111,8 +111,12 @@ jobs:
       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 ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DT8CODE_ENABLE_NETCDF=ON -DT8CODE_ENABLE_OCC=ON -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=$VTK_INSTALL_PATH/lib/cmake/vtk-9.1"
-        && echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV
+      run: |
+        export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
+                               -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE \
+                               -DT8CODE_BUILD_FORTRAN_INTERFACE=ON -DT8CODE_BUILD_MESH_HANDLE=ON \
+                               -DT8CODE_ENABLE_NETCDF=ON -DT8CODE_ENABLE_OCC=ON -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=$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 65602a32c3d0043c9242184e52ab280f36df5d23 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Fri, 16 Jan 2026 16:29:48 +0100
Subject: [PATCH 97/99] Set Fortran compiler

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index b66d05de54..6dddd22343 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -112,8 +112,9 @@ 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 ${TEST_LEVEL_FLAG} -GNinja -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
-                               -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE \
+        export CONFIG_OPTIONS="-DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx -DCMAKE_Fortran_COMPILER=mpifort -GNinja \
+                               -DT8CODE_ENABLE_MPI=$MPI -DCMAKE_BUILD_TYPE=$BUILD_TYPE ${TEST_LEVEL_FLAG} -DCMAKE_C_FLAGS_DEBUG=${DEBUG_CONFIG} -DCMAKE_CXX_FLAGS_DEBUG=${DEBUG_CONFIG} \
+                               -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON \
                                -DT8CODE_BUILD_FORTRAN_INTERFACE=ON -DT8CODE_BUILD_MESH_HANDLE=ON \
                                -DT8CODE_ENABLE_NETCDF=ON -DT8CODE_ENABLE_OCC=ON -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=$VTK_INSTALL_PATH/lib/cmake/vtk-9.1"
         echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV

From 5ad2d2798b18b685cddf48623a47b8fcb1e97e7f Mon Sep 17 00:00:00 2001
From: David Knapp <david.knapp@dlr.de>
Date: Tue, 27 Jan 2026 09:45:43 +0100
Subject: [PATCH 98/99] Update
 .github/workflows/test_t8code_w_clang_and_ompi.yml

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 6dddd22343..468edebefb 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -5,7 +5,7 @@ name: CMake tests t8code with Clang compiler and OpenMPI
 #  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) 2025 the developers
+#  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

From 492da40077a28080abf75a1a4022c8316aeddf57 Mon Sep 17 00:00:00 2001
From: Thomas Spenke <thomas.spenke@dlr.de>
Date: Wed, 28 Jan 2026 12:58:54 +0100
Subject: [PATCH 99/99] Set -DT8CODE_BUILD_WERROR=ON

---
 .github/workflows/test_t8code_w_clang_and_ompi.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_t8code_w_clang_and_ompi.yml b/.github/workflows/test_t8code_w_clang_and_ompi.yml
index 468edebefb..90da57089b 100644
--- a/.github/workflows/test_t8code_w_clang_and_ompi.yml
+++ b/.github/workflows/test_t8code_w_clang_and_ompi.yml
@@ -114,7 +114,7 @@ jobs:
       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=${DEBUG_CONFIG} \
-                               -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=OFF -DT8CODE_BUILD_WEXTRA=ON \
+                               -DT8CODE_BUILD_PEDANTIC=ON -DT8CODE_BUILD_WALL=ON -DT8CODE_BUILD_WERROR=ON -DT8CODE_BUILD_WEXTRA=ON \
                                -DT8CODE_BUILD_FORTRAN_INTERFACE=ON -DT8CODE_BUILD_MESH_HANDLE=ON \
                                -DT8CODE_ENABLE_NETCDF=ON -DT8CODE_ENABLE_OCC=ON -DT8CODE_ENABLE_VTK=ON -DVTK_DIR=$VTK_INSTALL_PATH/lib/cmake/vtk-9.1"
         echo CONFIG_OPTIONS="$CONFIG_OPTIONS" >> $GITHUB_ENV