Toward Instructions-as-Code: instruction files measurably move agentic PR merge rates — in both directions

arXiv·high signal

A study of 15,549 agentic pull requests across 148 projects finds mixed effects from instruction files (CLAUDE.md / AGENTS.md-style guidance): 27.7% of projects saw merge rates rise by at least 20% after adding instructions, while 26.35% saw decreases. Projects that improved had substantially longer, well-structured instruction files with more sections — quality and structure matter, not mere presence.