OSC 119 Reset Highlight Foreground Color
Put the highlight foreground color back as it started.
OSC 119 ST
OSC 119 ST puts the color of selected text, OSC 19, back as the terminal started it, undoing any change made with OSC 19 ; Pt ST. xterm resets it to the value it started with (ResetColorsRequest).
It takes no parameter. xterm ignores an OSC 119 that carries anything after the number, OSC 119 ; 1 ST say, as a malformed sequence (do_osc); an empty one, OSC 119 ; ST, is the same as none.
libghostty-vt has no such color, and ignores OSC 19 and OSC 119, so the case that asks is a known difference.
Validation
OSC119-1: After a change
\e]19;red\a
\e]119\a
\e]19;?\a
|____|
reply \e]19;rgb:ffff/ffff/ffff\a