MemoryLake on MemoryArena: A Matched Study of Agent Memory Backends

AuthorsChaoqun Zhan, Qiang Zhou, Guannan Li et al.

arXiv 20262026

TL;DR

MemoryLake uses structured multi-track memory with prioritized conclusions and evidence retrieval to reach a 20.5% macro-average SR vs 13.6% best baseline on MemoryArena.

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THE PROBLEM

Agent memory backends rarely tested on interdependent multi session tasks (20.5% vs 13.6% SR gap)

Most agent memory benchmarks focus on post hoc recall, not whether remembered information actually changes later actions or supports multi step objectives.

MemoryArena exposes that agents can recall facts yet still fail end to end tasks, leaving multi session, interdependent workloads under evaluated and poorly understood.

HOW IT WORKS

MemoryLake — Structured Multi Track Memory Backend

MemoryLake’s core mechanism separates confirmed conclusions, supporting evidence, and reusable experience into parallel tracks with different presence policies, all orchestrated through a shared gpt-5-mini backbone and bge-m3 dense retrieval.

You can think of MemoryLake like a computer with fast RAM for conclusions, a searchable disk for evidence, and a library of reusable procedures acting as cached skills.

This design lets MemoryLake keep critical conclusions always present, pull detailed evidence on demand, and reuse prior reasoning in ways a flat context window or naive vector RAG cannot.

DIAGRAM

MemoryLake Query Lifecycle Across Subtasks

This diagram shows how MemoryLake handles writes after each subtask and assembles memory before the next subtask in MemoryArena.

DIAGRAM

Matched System Level Evaluation on MemoryArena

This diagram shows the matched evaluation protocol comparing MemoryLake, Mem0, Vector RAG, and Long Context across five MemoryArena domains.

PROCESS

How MemoryLake Handles a MemoryArena Instance

  1. 01

    Matched system level protocol

    MemoryLake joins the shared MemoryArena agent framework with the gpt-5-mini alias and fixed task IDs, ensuring only the memory backend differs from Mem0, Vector RAG, and Long Context.

  2. 02

    Memory write after each subtask

    After every completed subtask, MemoryLake writes the full trajectory and outcome into its multi track store, populating confirmed conclusions, supporting evidence, and reusable experience.

  3. 03

    Presence policies for heterogeneous content

    MemoryLake prioritizes confirmed conclusions for future prompts, stores supporting evidence for bge-m3 dense retrieval, and consolidates reusable experience for transfer across subtasks.

  4. 04

    Bounded memory assembly and fallback

    Before each new subtask, MemoryLake assembles a bounded context from its tracks, and if the internal memory service fails, it returns an empty context so the agent can continue.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    Matched system level comparison

    MemoryLake is evaluated as a complete backend configuration against Mem0, Vector RAG, and Long Context across all five MemoryArena domains, using identical gpt-5-mini agents and task IDs.

  • 02

    End to end SR and process metrics

    MemoryLake reports both per domain SR and process metrics like PS, SPS, and step match, plus a 20.5% macro average SR compared to a 13.6% best comparator.

  • 03

    Workload level interpretation and transparency

    MemoryLake provides a workload dependent analysis of memory backends and documents sampling, judge dependence, and Mem0’s capped re run to clarify reproducibility limits.

RESULTS

By the Numbers

Math PS SR

29.5% PS / 22.5% SR

+10.0pp SR over Long Context

Physics PS SR

64.5% PS / 60.0% SR

+15.0pp SR over Mem0

Progressive PS SR

6.7% PS / 20.0% SR

+10.0pp SR over Vector RAG

Macro Avg SR

20.5%

+6.9pp over 13.6% Long Context

These metrics come from the shared MemoryArena evaluation sets, covering formal mathematics, physics, group travel planning, bundled web shopping, and progressive retrieval. The 20.5% macro average SR shows that MemoryLake achieves higher end to end success than the 13.6% best comparator under a matched agent and model configuration.

BENCHMARK

By the Numbers

These metrics come from the shared MemoryArena evaluation sets, covering formal mathematics, physics, group travel planning, bundled web shopping, and progressive retrieval. The 20.5% macro average SR shows that MemoryLake achieves higher end to end success than the 13.6% best comparator under a matched agent and model configuration.

BENCHMARK

Suite level Macro Avg SR on MemoryArena Shared Sets

Equal weight macro average SR across five MemoryArena domains.

KEY INSIGHT

The Counterintuitive Finding

In bundled web shopping, all four systems achieve only one bundle level success out of 150, with the sole success belonging to the Long Context baseline.

This is surprising because MemoryLake’s structured memory and Vector RAG’s retrieval achieve similar step match rates around 30%, yet none translate that into higher end to end SR under strict bundle success criteria.

WHY IT MATTERS

What this unlocks for the field

MemoryLake shows that structured multi track memory can shift end to end success on interdependent tasks, especially in formal reasoning and progressive retrieval.

Builders can now treat memory backends as workload specific design choices, using MemoryLake style presence policies when exact conclusion reuse and aggregation matter, rather than relying solely on longer context windows or naive vector RAG.

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