- Retry failed tests once (ctest --repeat until-pass:2) in every per-case test target; a clean run is unaffected and a genuinely broken test still fails. Covers the xvfb display-allocation miss, one-off network fetch failures and TCP echo timing seen on loaded runners. - Run all Linux xvfb steps on a 24-bit 1280x800 virtual screen (xvfb-run defaults to 640x480x8, a known cause of intermittent SDL/Vulkan window init failures).