Constraint Decay: LLM Agents Lose 30 Percentage Points When Backend Code Must Follow Architectural Rules

arXiv·high signal

Researchers quantify 'constraint decay' — as structural requirements accumulate (ORM patterns, API conventions, DB schemas), LLM agent code-gen performance drops ~30pp in assertion pass rates. Weaker configs approach zero. Flask handled well; Django and FastAPI trigger failures. Data-layer defects (wrong queries, ORM violations) are the leading root cause.