Personalize-then-Store: Benchmarking and Learning Personalized Memory for Long-horizon Agents

AuthorsYeonjun In, Wonjoong Kim, Sangwu Park et al.

arXiv 20262026

TL;DR

Personalize-then-Store uses session-level storage gating on PerMem-Bench to learn personalized memory policies, revealing large Oracle–Universal retention gaps under tight budgets.

SharePost on XLinkedIn

Read our summary here, or open the publisher PDF on the next tab.

THE PROBLEM

One-size-fits-all memory wastes budget on transient sessions

Existing LLM memory systems use universal, static policies that ignore user-specific agent use patterns and personalized worth-storing contexts.

This misalignment causes long-horizon agents to evict essential context, over-store transient interactions, and ultimately fail on multi-year, multi-domain tasks that require persistent personalized memory.

HOW IT WORKS

Personalize-then-Store via session-level storage gating

Personalize-then-Store introduces PerMem-Bench, PerMem-Benchs, PerMem-Benchd, and session-level storage gating with a structural note to benchmark and learn user-specific worth-storing sessions.

You can think of Personalize-then-Store as adding a smart circuit breaker in front of RAM, deciding which conversations deserve to be written to long-term disk.

This KEY_MECHANISM lets Personalize-then-Store concentrate a fixed memory budget on long-horizon projects, something a plain context window or universal storage policy cannot achieve.

DIAGRAM

Dual-simulator dialogue generation pipeline in PerMem-Bench

This diagram shows how Personalize-then-Store constructs PerMem-Bench dialogues from personas through life skeletons into dual-simulator conversations.

DIAGRAM

Evaluation protocol and memory retention measurement

This diagram shows how Personalize-then-Store evaluates memory systems on PerMem-Bench using session gating and Memory Retention Rate.

PROCESS

How Personalize-then-Store Handles a Long-horizon Interaction Session

  1. 01

    User-Specific Agent Use Profiling

    Personalize-then-Store infers per-user domain participation, frequency, and memory necessity, creating Mp,d triplets that define which domains need persistent storage.

  2. 02

    Life Skeleton and Timeline Construction

    Using the profile, Personalize-then-Store builds projects and events with reference memories, then arranges them into a unified multi-month timeline.

  3. 03

    Dialogue Generation via Dual-Simulator

    Personalize-then-Store runs a user simulator and agent simulator over the life skeleton to synthesize realistic long-horizon sessions with embedded worth-storing facts.

  4. 04

    Session-Level Storage Gating and Evaluation

    Personalize-then-Store applies Greedy, Context-aware, or Structure-aware gating, runs Mem0, Memory-R1, and RMM, and scores Memory Retention Rate over reference memories.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    PerMem-Bench for personalized memory

    Personalize-then-Store introduces PerMem-Bench with PerMem-Benchs and PerMem-Benchd, covering up to 32 month timelines, 1M tokens per user, and up to 146 reference memories.

  • 02

    Session-level storage gating paradigm

    Personalize-then-Store proposes session-level storage gating with Greedy, Context-aware, and Structure-aware methods that wrap existing systems like Mem0, Memory-R1, and RMM.

  • 03

    Empirical study of personalization limits

    Personalize-then-Store shows Structure-aware gating reaches F1 up to 0.844 on PerMem-Benchs, yet still leaves a large Oracle–Universal Memory Retention Rate gap under fixed budgets.

RESULTS

By the Numbers

F1 on PerMem-Benchs

0.844

+0.184 over Qwen3 14B Greedy

FNR on PerMem-Benchs

0.115

Structure-aware vs 0.457 for Qwen3 14B Greedy

F1 on PerMem-Benchd

0.805

+0.148 over Qwen3 14B Greedy

Dialogue quality score

98.4%

with 96.9% Gwet AC1 agreement in meta evaluation

On PerMem-Benchs and PerMem-Benchd, Personalize-then-Store evaluates session-level gating quality and memory behavior, showing Structure-aware gating can reach 0.844 F1 while the data pipeline maintains 98.4% dialogue quality.

BENCHMARK

By the Numbers

On PerMem-Benchs and PerMem-Benchd, Personalize-then-Store evaluates session-level gating quality and memory behavior, showing Structure-aware gating can reach 0.844 F1 while the data pipeline maintains 98.4% dialogue quality.

BENCHMARK

Session gating classification performance on PerMem-Benchs

F1 on PerMem-Benchs for different session-level storage gating methods and LLM backbones.

KEY INSIGHT

The Counterintuitive Finding

Personalize-then-Store shows Structure-aware gating achieves 0.844 F1 on PerMem-Benchs, yet only yields marginal Memory Retention Rate gains over Universal policies.

This is surprising because such high classification accuracy should translate directly into better retention, but compounding false positives and false negatives still squander the fixed memory budget.

WHY IT MATTERS

What this unlocks for the field

Personalize-then-Store unlocks a concrete way to study and benchmark personalized memory policies, separating user-specific worth-storing decisions from raw memory mechanisms.

Builders can now plug session-level storage gating into existing systems like Mem0 or RMM and quantify how much Oracle-level personalization could improve long-horizon retention under realistic memory budgets.

~12 min read← Back to papers

Related papers

BenchmarkAgent Memory

Active Context Compression: Autonomous Memory Management in LLM Agents

Nikhil Verma

· 2026

Focus Agent adds start_focus, complete_focus, a persistent Knowledge block, and an optimized Persistent Bash plus String-Replace Editor scaffold to actively compress context during long software-engineering tasks. On five hard SWE-bench Lite instances against a Baseline ReAct agent, Focus Agent achieves 22.7% token reduction (14.9M → 11.5M) while matching 3/5 = 60% task success.

Questions about this paper?

Paper: Personalize-then-Store: Benchmarking and Learning Personalized Memory for Long-horizon Agents

Answers use this explainer on Memory Papers.

Checking…