r/AI_Agents: Production Builders Document Silent Agent Memory Rot — Agents Act on Stale State After Month Three With No Staleness Signal

Production builders surfaced an emerging agent failure mode distinct from context-length or contradiction problems: memory systems that store facts indefinitely but have no mechanism to detect when stored beliefs are no longer true. After six months in production, agents retrieve outdated state and act on it confidently without staleness flags, creating a reliability gap that is invisible to standard logging and compounds with each new interaction cycle.