The Half-Life of an Instruction

A benchmark run on DeepSeek models finds that standing instructions erode fast: with thinking off, two earlier turns in French made V4 Pro ignore a "translate to Russian" rule in 90 of 90 trials, while thinking mode held at 89–100% through 50 turns. A single reminder beside the question also restored most adherence. A sliding-window memory cost 54% more than append-and-compact on a 12-turn replay, though that figure and the cache rules are DeepSeek-specific and come from the author's own runs. Rules that must hold belong in code.