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. Context grows with every step and nobody measured it.
How context accumulates
A multi-step agent accumulates its full conversation history by default. Every tool call result gets appended. Every intermediate reasoning step gets stored. The conversation object passed to each model call grows linearly with the number of steps executed.
