That sounds like a clever way to keep the narrative tight and the mood shifting just enough to keep readers on their toes. I’d recommend mapping each major plot beat to a distinct progression—maybe start with something bright, shift to a darker minor when the stakes rise, then resolve it back to a hopeful key. Just make sure you don’t let the music dictate the story entirely; let the characters steer it so it stays organic. It’s a good balance of order and subtle rebellion.