idempotent▌

Idempotent Redundancy \n When adding redundant paths (fallbacks, belt-and-suspenders), make them idempotent. \n Pattern \n Redundancy without idempotency causes loops, churn, or data corruption. \n DO \n \n Use _is_merge: true for Braintrust updates \n Check if value exists before writing (fallback only if missing) \n Use atomic write/rename for file operations \n Make reconciliation steps safe to run repeatedly \n \n DON'T \n \n Write unconditionally in fallback paths \n Allow multiple writers