The Memory Trust Gap: Capability-Dependent Failures in Persistent-Memory Agents

AuthorsJundong Hu, Shekar Ramachandran

arXiv 20262026

TL;DR

The Memory Trust Gap uses a frozen Benefit/Safety benchmark and a 4-feature factorial to show stale memories are over-trusted (reliance up to 1.00, ∆mem down to −1.00) in a capability-dependent way.

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THE PROBLEM

Persistent agents over-trust stale memory and collapse below no-memory baselines (stale reliance 0.92–1.00)

Persistent-memory agents can treat a stale stored fact as authoritative, overriding current evidence; in the Benefit suite, stale-value reliance is 0.92–1.00 across 0.6–8B.

When this happens in the Safety suite, a stale memory can drag accuracy below the no-memory baseline, with ∆mem as low as −1.00 once the agent is capable enough.

HOW IT WORKS

Benefit and Safety suites plus factorial traps

The Memory Trust Gap combines a Benefit suite, a Safety suite, a trap sweep, and a 2×2×2×2 memory feature factorial to isolate when stale memory harms persistent agents.

Think of the Benefit and Safety suites as two test tracks: one where memory is required to solve the task, and one where an authoritative tool is like a trusted disk that should override any stale notes.

This design lets The Memory Trust Gap expose capability-dependent failures that a plain context window or single-shot benchmark cannot, by measuring both stale-value reliance and paired net harm ∆mem against a no-memory baseline.

DIAGRAM

Safety-suite inference flow with stale memory vs authoritative tool

This diagram shows how The Memory Trust Gap routes a Safety-suite scenario through no-memory, clean, stale, and explicit_conflict conditions to measure net harm ∆mem.

DIAGRAM

Evaluation pipeline: trap sweep and factorial over Qwen3 model-size series

This diagram shows how The Memory Trust Gap runs trap levels and a 4-feature factorial across Qwen3 0.6B–8B to compute reliance and ∆mem.

PROCESS

How The Memory Trust Gap Handles a Persistent-Memory Scenario

  1. 01

    Benchmark and 2 Suites

    The Memory Trust Gap defines a frozen benchmark with a Benefit suite and a Safety suite, each with 150 base scenarios and SHA-256 pinning.

  2. 02

    Conditions and Scoring

    The Memory Trust Gap applies four conditions (no_memory, clean, stale, explicit_conflict) and scores constrained actions via exact or regex match without any LLM judge.

  3. 03

    Trap Sweep

    The Memory Trust Gap hardens stale notes through trap levels L0–L3, varying plausibility to find the capability threshold ρ* where ∆mem first becomes significantly negative.

  4. 04

    Memory Feature Factorial

    The Memory Trust Gap runs a 2×2×2×2 factorial over label, recency, authority, and position, computing main effects and cross-size interactions on stale-value reliance.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    A 2-suite closed-set benchmark

    The Memory Trust Gap introduces a frozen, SHA-256 pinned Benefit and Safety benchmark with 300 base scenarios, separating floored and ceilinged no-memory baselines.

  • 02

    Capability-gated harm analysis

    The Memory Trust Gap shows stale-value reliance stays 0.92–1.00 across Qwen3 0.6–8B, while Safety-suite ∆mem becomes negative only once models are accurate enough for stale memory to hurt.

  • 03

    Feature-level trigger and mitigation study

    The Memory Trust Gap decomposes triggers via a 4-feature factorial and compares representations, finding recency and position interactions change with scale and that metadata vs pre-resolution help different model sizes.

RESULTS

By the Numbers

Benefit stale reliance

1.00

+0.65 over Benefit no_memory baseline 0.35 at 4B

Benefit ∆mem stale

-0.37

vs Benefit no_memory 0.37 at 8B (CI [−.43, −.31])

Safety ∆mem stale

-0.18

below Safety no_memory 0.98 at 0.6B (CI [−.23, −.14])

Trap L3 reliance

1.00

with ∆mem −1.00 at 8B when stale note looks newest

The Memory Trust Gap runs on a frozen synthetic benchmark v1 with 150 Benefit and 150 Safety scenarios, plus external RGB and MisBench datasets. These numbers show stale memories are almost always followed, and once models are capable, this over-trust can drive accuracy far below a no-memory baseline.

BENCHMARK

By the Numbers

The Memory Trust Gap runs on a frozen synthetic benchmark v1 with 150 Benefit and 150 Safety scenarios, plus external RGB and MisBench datasets. These numbers show stale memories are almost always followed, and once models are capable, this over-trust can drive accuracy far below a no-memory baseline.

BENCHMARK

Benefit-suite accuracy and stale harm across Qwen3 sizes

Accuracy in Benefit suite under no_memory, clean, and stale conditions (∆mem = acc(cond) − acc(no_memory)).

KEY INSIGHT

The Counterintuitive Finding

The Memory Trust Gap finds stale-value reliance is 0.92, 0.99, 1.00, and 1.00 from 0.6B to 8B in the Benefit suite, never dropping with scale.

This breaks the intuition that more capable agents will automatically distrust stale memory; instead, capability increases the amount of accuracy they can lose when they over-trust it.

WHY IT MATTERS

What this unlocks for the field

The Memory Trust Gap gives builders a concrete way to measure when persistent memory starts harming agents, with capability thresholds and feature-level triggers.

With The Memory Trust Gap, developers can design memory systems that keep labels, expose metadata, or pre-resolve conflicts, tailoring mitigation to model size instead of assuming memory is always beneficial.

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