Context rot

Context rot is the degradation of a model's recall as its input gets longer, even when the task stays exactly as hard. Chroma held difficulty fixed and varied only the filler across 18 models and 194,480 calls; performance fell with length in every one of them. Anthropic describes the result as a performance gradient rather than a hard cliff. The working consequence is that a window has a useful capacity well below its stated one — which is why this catalog's handoff triggers at half.