CarMem: Enhancing Long-Term Memory in LLM Voice Assistants through Category-Bounding

AuthorsJohannes Kirmayr, Lukas Stappen, Phillip Schneider et al.

2025

TL;DR

CarMem uses category-bound preference extraction plus LLM-driven maintenance to achieve F1 between 0.78 and 0.95 on CARMEM while cutting redundant preferences by 95%.

SharePost on XLinkedIn

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

THE PROBLEM

Voice assistants forget preferences and extract too much private data

CarMem targets the issue that many systems struggle with retaining user preferences, leading to repetitive user requests and disengagement.

In in-car assistants, unbounded preference extraction conflicts with GDPR data minimization and EU AI Act transparency, causing privacy, trust, and resource problems.

HOW IT WORKS

Category-Bound Preference Memory System

CarMem centers on Preference Extraction, Preference Maintenance, and Preference Retrieval, all constrained by a hierarchical, predefined category schema for in-car preferences.

You can think of CarMem like a card catalog for car-related preferences, where each card is filed under specific shelves such as Vehicle Settings and Comfort or Entertainment.

By bounding extraction to actionable categories, CarMem enables transparent, opt-out friendly long-term memory that a plain context window cannot provide without violating data minimization.

DIAGRAM

Conversation to Memory Flow in CarMem

This diagram shows how CarMem processes multi turn in car conversations to extract, maintain, and later retrieve preferences.

DIAGRAM

CARMEM Dataset Generation and Evaluation Pipeline

This diagram shows how CARMEM is generated and then used to benchmark extraction, maintenance, and retrieval in CarMem.

PROCESS

How CarMem Handles a User Assistant Conversation Session

  1. 01

    Preference Extraction

    CarMem runs Preference Extraction with LLM function calling over the conversation, filling a hierarchical schema of main, sub, and detail categories.

  2. 02

    Preference Maintenance

    CarMem applies Preference Maintenance functions pass, update, and append, comparing incoming preferences with existing ones per detail category.

  3. 03

    Preference Retrieval

    CarMem performs Preference Retrieval by embedding detail category, attribute, and sentence, then retrieving top n preferences per subcategory for a new utterance.

  4. 04

    Personalized Response Generation

    CarMem supplies retrieved preferences to the in car assistant, enabling personalized responses aligned with vehicle functions and user opt out choices.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    Category-bound preference memory system

    CarMem introduces a category-bound preference memory system with Preference Extraction, Preference Maintenance, and Preference Retrieval tailored to in car assistants, reaching detail-level F1 of 0.78.

  • 02

    Closed-world in-car conversational dataset CARMEM

    CarMem provides the synthetic closed world dataset CARMEM with 1,000 Extraction Conversations, 1,000 Retrieval Utterances, and 3,000 Maintenance Utterances for systematic memory evaluation.

  • 03

    LLM-driven maintenance with strong redundancy reduction

    CarMem extends LLM driven maintenance with function calling, achieving a 95% reduction in redundant preferences and 93% reduction in contradictory preferences in Maintenance Utterances.

RESULTS

By the Numbers

Detail F1

0.78 F1

detail level precision 0.75 and recall 0.81 in 41 categories

Main F1

0.94 F1

main level precision 0.93 and recall 0.94 across 4 categories

Redundant reduction

95% reduction

reduction in redundant preferences via maintenance compared to naive append

Optimal retrieval

0.87 accuracy

top n accuracy using enriched embeddings with detail category and attribute

On the CARMEM dataset, CarMem is evaluated for extraction, maintenance, and retrieval in an in car voice assistant setting. These results show that CarMem can reliably structure preferences, keep storage consistent, and retrieve relevant memories under a realistic closed world scenario.

BENCHMARK

By the Numbers

On the CARMEM dataset, CarMem is evaluated for extraction, maintenance, and retrieval in an in car voice assistant setting. These results show that CarMem can reliably structure preferences, keep storage consistent, and retrieve relevant memories under a realistic closed world scenario.

BENCHMARK

Extraction Performance Across Category Levels on CARMEM

Micro averaged F1 scores for preference extraction at main, sub, and detail category levels.

KEY INSIGHT

The Counterintuitive Finding

CarMem’s Out of Schema experiment shows that when a subcategory is excluded, non extraction is achieved 75% of the time, despite complex conversations.

This is surprising because LLMs often over extract, yet CarMem’s function schema strongly bounds extraction, contradicting the assumption that LLM memories must be unstructured and noisy.

WHY IT MATTERS

What this unlocks for the field

CarMem unlocks controllable, category bound long term memory for voice assistants, aligning personalization with GDPR and EU AI Act transparency requirements.

Builders can now deploy in car assistants that remember actionable preferences, let users opt out per category, and maintain clean memory stores without bespoke infrastructure.

~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: CarMem: Enhancing Long-Term Memory in LLM Voice Assistants through Category-Bounding

Answers use this explainer on Memory Papers.

Checking…