diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index d6e4202..506ba54 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -25,17 +25,35 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
 
+      # ADDED: System dependencies for Qt/GUI required by Ubuntu
+      - name: Install system dependencies (Ubuntu)
+        if: runner.os == 'Linux'
+        run: |
+          sudo apt-get update -qq
+          sudo apt-get install -y --no-install-recommends \
+            libgl1 libglx-mesa0 libegl1 libegl-mesa0 \
+            libxcb-xinerama0 libxcb-icccm4 libxcb-image0 \
+            libxcb-render-util0 libxkbcommon-x11-0 \
+            x11-utils xvfb
+
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
           pip install -r requirements.txt
           pip install pytest pytest-cov
 
+      # ADDED: Environment variables for headless Qt testing
       - name: Run ALL tests (library, API, scripts, integration)
+        env:
+          QT_QPA_PLATFORM: offscreen
+          DISPLAY: ":99"
         run: |
           python -m pytest tests/ -v --tb=short
           
       - name: Verify package imports
+        env:
+          QT_QPA_PLATFORM: offscreen
+          DISPLAY: ":99"
         run: |
           python -c "from src.core.flow_model import TwoPhaseFlowModel; print('Import OK')"
 
@@ -95,4 +113,4 @@ jobs:
       - name: Publish to PyPI
         uses: pypa/gh-action-pypi-publish@release/v1
         with:
-          password: ${{ secrets.PYPI_API_TOKEN }}
+          password: ${{ secrets.PYPI_API_TOKEN }}
\ No newline at end of file