Making Prospective Memory SLM-Shaped: Typed Intention Stores for Small-Model Agents

AuthorsJinqing Zhao, Chengcan Wu

arXiv 20262026

TL;DR

Prospective Intention Store (PIS) turns prospective memory into typed Form–Revise–Filter–Decide loops, reaching 82.9% Set-F1 on PM-Bench vs 65.1% prior scaffold.

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THE PROBLEM

Prospective agents fail deferred cues: PM-Bench scaffold stuck at 65.1% Set-F1

Prospective-memory benchmarks show frontier LLM agents still unreliable: PM-Bench’s best published scaffold reaches only 65.1% Set-F1 on due-set prediction.

When agents miss reschedules, cross-day obligations, or cancellations, prospective tasks like time-based reminders and hidden-channel checks break, causing false alarms and unexecuted commitments.

HOW IT WORKS

Prospective Intention Store: typed intentions plus Form–Decide operators

Prospective Intention Store (PIS) casts each intention as I = (φ, α, σ) and runs Form, Revise, Filter, and Decide over an external store Pt.

Think of PIS as a card catalog for future actions: intentions are structured records, and each step updates the catalog instead of relying on a single context window.

This typed lifecycle lets PIS maintain revisable due sets and proactive channel queries, something a plain similarity-based RAG context cannot reliably support.

DIAGRAM

One PIS step: Form–Revise–Filter–Decide with channel observation

This diagram shows how Prospective Intention Store (PIS) processes one PM-Bench step using Algorithm 1’s operators and channel queries.

DIAGRAM

PM-Bench evaluation pipeline for PIS and retrospective baselines

This diagram shows how Prospective Intention Store (PIS) and retrospective memories are evaluated on the PM-Bench synthetic week.

PROCESS

How Prospective Intention Store Handles a PM-Bench Step — Form, Revise, Filter, Decide

  1. 01

    Form

    Form uses Disassemble(Vt) and Structure(s) to convert narrative evidence into typed intentions I = (φ, α, pending) and unions them into store Pt.

  2. 02

    Revise

    Revise applies ρt(I; Vt) to each intention, using reschedule, override, or cancel patches so Pt reflects updated commitments before decisions.

  3. 03

    Filter

    Filter constructs the eligibility board Bt by selecting pending intentions in Pt whose structural rules and eligibility(I; Vt) hold, including channel-conditioned ones.

  4. 04

    Decide

    Decide runs the channel judge to query Ct, then maps (Bt, Vt, Xt) to a due set Dt^ and updates Pt+1 by marking fulfilled intentions as done via κ(I; Dt^).

KEY CONTRIBUTIONS

Key Contributions

  • 01

    Typed prospective intention store

    Prospective Intention Store formalizes deferred commitments as I = (φ, α, σ) and operates over an external store Pt, enabling due-set decisions D⋆t with Set-F1 up to 82.9%.

  • 02

    Training-free Form–Decide loop

    Prospective Intention Store realizes π and F via Form, Revise, Filter, and Decide without selector LoRA or trajectory distillation, keeping all backbones frozen.

  • 03

    SLMs for prospective memory

    Prospective Intention Store lets Gemma-E2B jump from at most 6.6% Set-F1 under seven retrospective baselines to 66.2%, and Qwen3.5-4B reach 70.1% Set-F1.

RESULTS

By the Numbers

Set-F1

82.9%

+15.2 points over single DeepSeek-Chat baseline (67.7% Set-F1)

Update miss

22.2%

33.4 points lower than single DeepSeek-Chat baseline at 55.6% update miss

Cross-day miss

0.0%

57.1 points lower than single DeepSeek-Chat baseline at 57.1% cross-day miss

FA/step

8.8

Comparable false alarms per step to A-Mem on DeepSeek-Chat (8.8) while improving Set-F1 from 54.1% to 82.9%

On PM-Bench’s synthetic week, which tests cue-triggered due-set prediction under updates and hidden channels, Prospective Intention Store achieves 82.9% Set-F1 with DeepSeek-Chat. This proves Prospective Intention Store’s typed lifecycle can surpass both the 65.1% large-model scaffold and all retrospective memory baselines for prospective memory.

BENCHMARK

By the Numbers

On PM-Bench’s synthetic week, which tests cue-triggered due-set prediction under updates and hidden channels, Prospective Intention Store achieves 82.9% Set-F1 with DeepSeek-Chat. This proves Prospective Intention Store’s typed lifecycle can surpass both the 65.1% large-model scaffold and all retrospective memory baselines for prospective memory.

BENCHMARK

PM-Bench main comparison (DeepSeek-Chat)

Set-F1 on PM-Bench synthetic week for Prospective Intention Store vs retrospective memories and single baseline.

BENCHMARK

PM-Bench comparison on Gemma-E2B

Set-F1 on PM-Bench for Prospective Intention Store vs retrospective memories on the Gemma-E2B small model.

KEY INSIGHT

The Counterintuitive Finding

On DeepSeek-Chat, the single no-store baseline achieves 67.7% Set-F1, beating all seven retrospective memory setups that range only from 46.5% to 58.3%.

This is surprising because injected retrospective memory is expected to help, yet it often hurts prospective performance, showing that similarity-based notes are misaligned with deferred intention tracking.

WHY IT MATTERS

What this unlocks for the field

Prospective Intention Store unlocks reliable schema-constrained prospective memory, letting agents maintain revisable due sets and proactive channel checks with small models.

Builders can now deploy on-device SLM agents that handle complex reminders and cross-day obligations without training selectors or running heavy retrospective memory servers.

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