Coding agents re-send their whole history every turn, so on a long task the model re-reads the same build output dozens of times, and you pay for every read. OptScale Kompressor stops that: on Terminal-Bench 2.1 it takes 22.7% off the real bill. The same input compresses to the same bytes every turn, so the prompt cache keeps working, and every removed detail stays one retrieval away. Open source (MIT), one Rust binary, no ML model.