A study of 1,867 repositories reports agent instruction files more than triple over their lifetime and older instructions are less likely to be deleted

Sources: primary, discussion
Summary: The preprint measures 247,694 instruction lifetimes across 1,867 repositories and reports 226 percent growth in agent instruction files and 4.9 net added instructions per commit. It reports that older instructions are less likely to be deleted than newer ones. The authors argue the cause is that a deleted instruction whose rationale is gone cannot be checked cheaply.
Why it matters: The paper puts measured numbers on a maintenance failure mode that teams running agent instruction files already encounter.
Follow-up: Track whether the preprint reaches peer review and whether the dataset is published.