Agent harness affects cache efficiency and energy use
Neuralwatt's analysis of a month of cloud traffic found agent harnesses caused 1.6%–11.1% uncached input. A cache miss roughly doubles request energy, 2.5x on GLM-5.3; in deep sessions beyond 128k tokens, re-reading over half the prompt costs as much prefill as ~600 normal turns. All cache breaks came from harnesses editing sent content, so most issues are fixable.