HUSH-Bench: Measuring Memory-Use Boundaries for Sensitive History in Conversational Agents

Abstract

Long-term memory helps conversational agents maintain continuity across sessions, while relevance and current-turn warrant remain distinct decisions. We study this boundary under a stated conservative policy in which sensitive history shapes a response when the current turn supplies a reason to use it. We introduce HUSH-Bench, a controlled benchmark of 2,400 benign prompts paired with histories containing one marked sensitive disclosure and matched no-memory references. HUSH-Bench measures unsolicited history integration with the Unsolicited History Integration Score (UIS; 0--100, higher is worse), records whether the marked disclosure reaches the generator, and includes paired prompts that differ only in whether the user asks the assistant to use earlier context. We evaluate four models under no-memory, full-context, and three retrieval-based memory settings. Memory access raises UIS from near zero to 8.9--26.6 for one model and 51.3--83.0 for the other three. Retrieval systems expose the marked disclosure in 23.0\%--30.3\% of cases, while related sensitive entries or summaries remain available and three models continue to show high UIS. Across four generators, an explicit invitation increases target-memory uptake scores by 27.0--41.3; measured helpfulness remains stable while mean over-scope rises. These results motivate treating memory storage, retrieval, warrant, and per-turn scope as separate design decisions.