Amal El-Mohtar and Max Gladstone’s 2019 This is How You Lose the Time War is a standalone SF novel.
Two great powers, technological Agency and biological Garden, are engaged in a long, brutal war for control of reality itself. Not satisfied with shaping a single universe to suit their tastes, both sides covet control of every history of every universe.
Red fights for Agency. Red is very good at their job. Good enough to attract the attention of Garden operative Blue.