Idempotent Redundancy When adding redundant paths (fallbacks, belt-and-suspenders), make them idempotent. Pattern Redundancy without idempotency causes loops, churn, or data corruption. DO - Use for Braintrust updates - Check if value exists before writing (fallback only if missing) - Use atomic write/rename for file operations - Make reconciliation steps safe to run repeatedly DON'T - Write unconditionally in fallback paths - Allow multiple writers to overwrite each other - Fire "repair" actions that can trigger more repairs Source Sessions - a541f08a: "Redundancy is good only if idempotent"…