Context window growth is the silent failure mode in agentic pipelines

Context window management is the invisible cost in every multi-step agent pipeline. I see this pattern across production consulting work. An agent that works cleanly in testing — ten steps, coherent reasoning, correct output — starts degrading six weeks after ship. No errors. No crashes. Just drift. Outputs get shorter. Reasoning steps that used to show clear logic start reading like vague summaries. Users start noticing that the agent "feels slower." The root cause is almost always the same.…