Different Type of Time Travel Story
A time travel novel that is about a war, but not really; nor is it really about the opposing forces and their reasons for fighting. It's about an agent of each side Red from the Agency and Blue from the Garden. Each faction believes it's version of a healthy future is the only way to survive, and the way humanity must persevere. Agency is very tech focused and the Garden is nature focused.
Both groups fight by sending their operatives to different Strands (think of a multiverse) to make small adjustments to bring about slightly different outcomes that will have a butterfly effect on the timeline.
Red and Blue are overlapping, haunting each other's missions and slightly sabotaging each other, and have been for awhile. When they start communicating with each other through over the top coded messages (i.e. burn a message before reading!) their dynamic changes.
A sci-fi book not about war, not actually about the future, but about two sides caught in opposition to each other that journey towards something different.