diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9f5b73b..58062db 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -60,9 +60,9 @@ jobs:
       matrix:
         python-version: ['3.9', '3.10', '3.11', '3.12']
         os: [ubuntu-latest]
-        include:
-        - os: macos-latest
-          python-version: '3.12'
+        # include:
+        # - os: macos-latest
+        #   python-version: '3.12'
 
     runs-on: ${{ matrix.os }}
 
@@ -70,10 +70,6 @@ jobs:
 
     steps:
 
-    - uses: actions/setup-python@v5
-      with:
-        python-version: ${{ matrix.python-version }}
-
     - name: Git Checkout ${{ github.action_repository }}
       uses: actions/checkout@v4
 
@@ -83,16 +79,8 @@ jobs:
     - uses: ./.github/workflows/composite-gemini3d
       timeout-minutes: 15
 
-    - name: Install Python packages
-      run: python -m pip install .[tests,plots]
-      timeout-minutes: 5
-      # transient CI download speed
-
-    - name: Unit and Integration Tests
-      run: pytest ${{ github.workspace }}
+    - uses: ./.github/workflows/composite-python
       timeout-minutes: 15
-      env:
-        GEMCI_ROOT: ${{ github.workspace }}/gemci
 
 # codecov coverage
     # - run: pip install codecov pytest-cov
diff --git a/.github/workflows/composite-gemini3d/action.yml b/.github/workflows/composite-gemini3d/action.yml
index c4782f5..95d1894 100644
--- a/.github/workflows/composite-gemini3d/action.yml
+++ b/.github/workflows/composite-gemini3d/action.yml
@@ -1,45 +1,45 @@
 runs:
 
-    using: 'composite'
+  using: 'composite'
 
-    steps:
+  steps:
 
-    - name: GCC compiler (macOS)
-      shell: bash
-      if: runner.os == 'macOS'
-      run: |
-        echo "CC=gcc-13" >> $GITHUB_ENV
-        echo "CXX=g++-13" >> $GITHUB_ENV
-        echo "FC=gfortran-13" >> $GITHUB_ENV
+  - name: GCC compiler (macOS)
+    shell: bash
+    if: runner.os == 'macOS'
+    run: |
+      echo "CC=gcc-13" >> $GITHUB_ENV
+      echo "CXX=g++-13" >> $GITHUB_ENV
+      echo "FC=gfortran-13" >> $GITHUB_ENV
 
-    - name: Checkout GemGI (for simulation config.nml inputs)
-      uses: actions/checkout@v4
-      with:
-        repository: gemini3d/gemci
-        path: ${{ github.workspace }}/gemci
+  - name: Checkout GemGI (for simulation config.nml inputs)
+    uses: actions/checkout@v4
+    with:
+      repository: gemini3d/gemci
+      path: ${{ github.workspace }}/gemci
 
-    - name: Cache install Gemini3D
-      id: cache-gemini
-      uses: actions/cache@v4
-      with:
-        path: |
-          ${{ env.CMAKE_INSTALL_PREFIX }}
-        key: ${{ runner.os }}-gemini-${{ hashFiles('gemini3d/CMakeLists.txt') }}
-      # weak check that gemini3d has changed since last cache update
+  - name: Cache install Gemini3D
+    id: cache-gemini
+    uses: actions/cache@v4
+    with:
+      path: |
+        ${{ env.CMAKE_INSTALL_PREFIX }}
+      key: ${{ runner.os }}-gemini-${{ hashFiles('gemini3d/CMakeLists.txt') }}
+    # weak check that gemini3d has changed since last cache update
 
-    - name: Checkout Gemini3D
-      if: steps.cache-gemini.outputs.cache-hit != 'true'
-      uses: actions/checkout@v4
-      with:
-        repository: gemini3d/gemini3d
-        path: gemini3d
-        submodules: true
+  - name: Checkout Gemini3D
+    if: steps.cache-gemini.outputs.cache-hit != 'true'
+    uses: actions/checkout@v4
+    with:
+      repository: gemini3d/gemini3d
+      path: gemini3d
+      submodules: true
 
-    - name: non-cache Install Gemini3D
-      if: steps.cache-gemini.outputs.cache-hit != 'true'
-      shell: bash
-      run: |
-        cmake -B build
-        cmake --build build
-        cmake --install build
-      working-directory: gemini3d
+  - name: non-cache Install Gemini3D
+    if: steps.cache-gemini.outputs.cache-hit != 'true'
+    shell: bash
+    run: |
+      cmake -B build
+      cmake --build build
+      cmake --install build
+    working-directory: gemini3d
diff --git a/.github/workflows/composite-python/action.yml b/.github/workflows/composite-python/action.yml
new file mode 100644
index 0000000..30aa94d
--- /dev/null
+++ b/.github/workflows/composite-python/action.yml
@@ -0,0 +1,19 @@
+runs:
+
+  using: 'composite'
+
+  steps:
+
+  - uses: actions/setup-python@v5
+    with:
+      python-version: ${{ matrix.python-version }}
+
+  - name: Install Python packages
+    run: python -m pip install .[tests,plots]
+    shell: bash
+
+  - name: Unit and Integration Tests
+    run: pytest ${{ github.workspace }}
+    shell: bash
+    env:
+      GEMCI_ROOT: ${{ github.workspace }}/gemci