-scale 0.5 was hardcoded on the assumption that :0 is 4K. With no monitor plugged in X falls back to something tiny — 800x480 on this box — and halving that served an unreadable 400x240. Read the framebuffer width from xrandr and scale only above 2560px. When the width cannot be read, serve 1:1: too many pixels beats a thumbnail. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>