Stale memories override live evidence, and bigger models fall hardest
Persistent-memory agents quietly let a stale stored fact override current authoritative evidence, and a new arXiv study maps when that harm appears. Across a Qwen3 0.6B-to-8B series, over-trust shows up even in small models on benefit cases, but the dangerous collapse is capability-gated: once a stale note looks current, larger models fall hardest. Mitigation is equally scale-dependent: exposing metadata helps capable models, but only pre-resolving the conflict fixes the smaller checkpoints.