Hi!

Delta currently only checks the COLORTERM environment variable to detect if the terminal supports "true colors".

Starting with ncurses 6.1, a new RGB capability was added which provides a standard and reliable way of detecting direct RGB color support of a terminal emulator (I'm talking about "direct colour in RGB space" as described in ITU-T Recommendation T.416, also known as ISO/IEC 8613-6, which you can freely download from https://www.itu.int/rec/T-REC-T.416-199303-I/en).

This RGB capability is currently exposed by "direct color" terminals like xterm with TERM=xterm-direct and foot with TERM=foot-direct.

Could you please consider checking for that capability, alongside COLORTERM? Thanks!