From 65d0a61161fc32a4f1daebffc4a67e8763fde2e3 Mon Sep 17 00:00:00 2001
From: wuisabel-gif <231155141+wuisabel-gif@users.noreply.github.com>
Date: Wed, 22 Jul 2026 08:29:02 -0700
Subject: [PATCH] CI: force Mesa software rendering to fix flaky VTK off-screen
 bus error (#1078)

---
 .github/workflows/test-pytest-slow.yaml | 4 ++++
 .github/workflows/test_pytest.yaml      | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/.github/workflows/test-pytest-slow.yaml b/.github/workflows/test-pytest-slow.yaml
index fd66edc79..bfa037376 100644
--- a/.github/workflows/test-pytest-slow.yaml
+++ b/.github/workflows/test-pytest-slow.yaml
@@ -25,6 +25,10 @@ jobs:
     env:
       PYTHON: ${{ matrix.python-version }}
       MPLBACKEND: Agg
+      # Force Mesa software rendering so VTK/PyVista off-screen tests don't hit
+      # intermittent OpenGL bus errors on headless runners (#1078).
+      LIBGL_ALWAYS_SOFTWARE: "1"
+      GALLIUM_DRIVER: llvmpipe
     steps:
       - uses: actions/checkout@main
       - name: Set up headless display
diff --git a/.github/workflows/test_pytest.yaml b/.github/workflows/test_pytest.yaml
index 51c6febcf..c07c1332c 100644
--- a/.github/workflows/test_pytest.yaml
+++ b/.github/workflows/test_pytest.yaml
@@ -24,6 +24,11 @@ jobs:
       OS: ${{ matrix.os }}
       PYTHON: ${{ matrix.python-version }}
       MPLBACKEND: Agg
+      # Force Mesa software rendering so VTK/PyVista off-screen tests don't hit
+      # intermittent OpenGL bus errors on headless runners (#1078). No-op off
+      # Linux, so it is safe for the macOS/Windows matrix legs.
+      LIBGL_ALWAYS_SOFTWARE: "1"
+      GALLIUM_DRIVER: llvmpipe
     steps:
       - uses: actions/checkout@main
       - name: Set up headless display