My Emacs configuration https://git.cjennings.net/dotemacs/atom?h=main 2026-04-22T16:45:19+00:00 2026-04-22T16:45:19+00:00 Craig Jennings c@cjennings.net 2026-04-22T16:45:19+00:00 urn:sha1:848a2d52c9eb796dac94a6f263b0518abe580c69 `env-laptop-p` treated any `battery-format "%B"` value that wasn't literally "N/A" as "has a battery." On a Linux desktop using `battery-upower`, the result is "unknown". The AC adapter and USB-C power entries exist in /sys but there's no BAT*. That made desktops look like laptops. The per-machine font height switch in `font-config.el` broke as a result. The fix uses /sys/class/power_supply/BAT* as the canonical Linux signal. That's what the kernel exposes, and what upower itself reads. Other platforms keep the `battery-format` path, but the fallback now checks for a live battery status char ("!", "+", "-") instead of only excluding "N/A". Two pure helpers (`env--battery-status-char-indicates-battery-p`, `env--power-supply-has-battery-p`) keep the logic testable. The new test file covers Normal, Boundary, and Error cases for each helper.