Proactive Memory for Ad-Hoc Recall over Streaming Dialogues
Organizations: Department of Computing The Hong Kong Polytechnic University · The School of Computer Science and Technology Harbin Institute of Technology (Shenzhen)
Abstract
Real-world dialogue usually unfolds as an infinite stream. It thus requires bounded-state memory mechanisms to operate within an infinite horizon. However, existing read-then-think memory is fundamentally misaligned with this setting, as it cannot support ad-hoc memory recall while streams unfold. To explore this challenge, we introduce STEM-Bench, the first benchmark for STreaming Evaluation of Memory. It comprises over 14K QA pairs in dialogue streams that assess perception fidelity, temporal reasoning, and global awareness under infinite-horizon constraints. The preliminary analysis on STEM-Bench indicates a critical textit{fidelity-efficiency dilemma}: retrieval-based methods use fragment context, while full-context models incur unbounded latency. To resolve this, we propose ProStream, a proactive memory framework for streaming dialogues built on a hierarchical structure. It enables ad-hoc memory recall on demand by reasoning over continuous streams with multi-granular distillation. Moreover, it employs Adaptive Spatiotemporal Optimization to dynamically optimize retention based on expected utility. It enables a bounded knowledge state for lower inference latency without sacrificing reasoning fidelity. Experiments show ProStream delivers higher reasoning fidelity than prior baselines while maintaining substantially lower latency than full-context alternatives.
Figures & tables
| Method | The Big Bang Theory | Friends | The Office | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Time | B-4 | R-L | B-S | Evid. | KEM | Gem | Time | B-4 | R-L | B-S | Evid. | KEM | Gem | Time | B-4 | R-L | B-S | Evid. | KEM | Gem | |
| RAG | 0.957 | 0.068 | 0.247 | 0.781 | 0.355 | 0.508 | 0.331 | 0.923 | 0.061 | 0.231 | 0.768 | 0.345 | 0.502 | 0.309 | 0.918 | 0.074 | 0.271 | 0.778 | 0.322 | 0.524 | 0.385 |
| RQ-RAG | 5.149 | 0.051 | 0.201 | 0.770 | 0.275 | 0.460 | 0.329 | 5.098 | 0.043 | 0.184 | 0.758 | 0.372 | 0.439 | 0.313 | 1.058 | 0.072 | 0.270 | 0.780 | 0.466 | 0.535 | 0.376 |
| RAPTOR | 0.519 | 0.041 | 0.165 | 0.761 | 0.302 | 0.375 | 0.214 | 0.513 | 0.035 | 0.157 | 0.746 | 0.396 | 0.367 | 0.214 | 0.443 | 0.032 | 0.142 | 0.745 | 0.324 | 0.334 | 0.201 |
| Full Context | 7.333 | 0.065 | 0.249 | 0.737 | 0.250 | 0.710 | 0.521 | 4.870 | 0.057 | 0.241 | 0.732 | 0.360 | 0.706 | 0.505 | 4.776 | 0.066 | 0.266 | 0.742 | 0.292 | 0.731 | 0.574 |
| Summary | 2.001 | 0.049 | 0.200 | 0.783 | 0.296 | 0.407 | 0.278 | 2.352 | 0.042 | 0.180 | 0.762 | 0.334 | 0.385 | 0.246 | 1.641 | 0.048 | 0.201 | 0.770 | 0.365 | 0.397 | 0.272 |
Appendix figures & tables7 assets
Supplementary material from the paper’s appendix.
Appendix
| Backbone | Variant | The Big Bang Theory | Friends | The Office | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Time | B-4 | R-L | B-S | Evid. | KEM | Gem | Time | B-4 | R-L | B-S | Evid. | KEM | Gem | Time | B-4 | R-L | B-S | Evid. | KEM | Gem | ||
| BGE | RAG | 0.814 | 0.087 | 0.301 | 0.796 | 0.583 | 0.572 | 0.413 | 0.814 | 0.081 | 0.296 | 0.785 | 0.621 | 0.576 | 0.399 | 0.801 | 0.094 | 0.339 | 0.796 | 0.647 | 0.611 | 0.413 |
| our | 0.393 | 0.116 | 0.383 | 0.816 | 0.460 | 0.623 | 0.498 | 0.442 | 0.097 | 0.354 | 0.802 | 0.464 | 0.597 | 0.469 | 0.516 | 0.114 | 0.407 | 0.819 | 0.484 | 0.622 | 0.498 | |
| UAE | RAG | 0.774 | 0.086 | 0.296 | 0.794 | 0.583 | 0.572 | 0.410 | 0.788 | 0.082 | 0.296 | 0.785 | 0.619 | 0.573 | 0.408 | 0.756 | 0.093 | 0.337 | 0.796 | 0.650 | 0.612 | 0.410 |
| our | 0.825 | 0.116 | 0.386 | 0.818 | 0.482 | 0.615 | 0.501 | 0.829 | 0.098 | 0.357 | 0.802 | 0.482 | 0.592 | 0.471 | 0.688 | 0.117 | 0.413 | 0.821 | 0.503 | 0.624 | 0.501 | |
| MiniLM | RAG | 1.225 | 0.064 | 0.240 | 0.781 | 0.389 | 0.500 | 0.331 | 1.162 | 0.060 | 0.237 | 0.774 | 0.424 | 0.497 | 0.309 | 1.067 | 0.072 | 0.269 | 0.781 | 0.466 | 0.533 | 0.331 |
| (a) Sensitivity to | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Setting | The Big Bang Theory | Friends | The Office | ||||||||||||
| B-4 | R-L | B-S | Evid. | KEM | B-4 | R-L | B-S | Evid. | KEM | B-4 | R-L | B-S | Evid. | KEM | |
| 0.5 | 0.15 | 0.43 | 0.85 | 0.51 | 0.64 | 0.12 | 0.39 | 0.82 | 0.52 | 0.62 | 0.14 | 0.46 | 0.84 | 0.50 | 0.69 |
| 0.6 | 0.16 | 0.44 | 0.85 | 0.51 | 0.66 | 0.12 | 0.40 | 0.82 | 0.52 | 0.63 | 0.14 | 0.46 | 0.83 | 0.50 | 0.68 |
| 0.7 | 0.12 | 0.39 | 0.82 | 0.49 | 0.61 | 0.10 | 0.36 | 0.80 | 0.49 | 0.59 | 0.11 | 0.41 | 0.82 | 0.49 | 0.63 |
| 0.8 | 0.16 | 0.45 | 0.85 | 0.49 | 0.68 | 0.11 | 0.39 | 0.82 | 0.52 | 0.62 | 0.14 | 0.46 | 0.83 | 0.51 | 0.67 |
| Setting | The Big Bang Theory | Friends | The Office | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| B-4 | R-L | B-S | Evid. | KEM | B-4 | R-L | B-S | Evid. | KEM | B-4 | R-L | B-S | Evid. | KEM | |
| Full | 0.16 | 0.44 | 0.85 | 0.51 | 0.66 | 0.13 | 0.40 | 0.82 | 0.52 | 0.62 | 0.14 | 0.46 | 0.83 | 0.50 | 0.68 |
| Perturb | 0.15 | 0.44 | 0.85 | 0.50 | 0.66 | 0.13 | 0.41 | 0.83 | 0.52 | 0.64 | 0.15 | 0.46 | 0.84 | 0.51 | 0.66 |
| Perturb | 0.16 | 0.44 | 0.85 | 0.51 | 0.66 | 0.13 | 0.40 | 0.82 | 0.52 | 0.62 | 0.14 | 0.46 | 0.83 | 0.50 | 0.68 |
| Perturb | 0.16 | 0.44 | 0.85 | 0.51 | 0.66 | 0.12 | 0.40 | 0.82 | 0.52 | 0.63 | 0.14 | 0.46 | 0.83 | 0.51 | 0.68 |
| The Big Bang Theory | Friends | The Office | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| B-4 | R-L | B-S | Evid. | KEM | B-4 | R-L | B-S | Evid. | KEM | B-4 | R-L | B-S | Evid. | KEM | |
| 50k | 0.15 | 0.41 | 0.82 | 0.16 | 0.53 | 0.11 | 0.35 | 0.79 | 0.23 | 0.48 | 0.15 | 0.44 | 0.82 | 0.21 | 0.57 |
| 75k | 0.15 | 0.40 | 0.82 | 0.16 | 0.53 | 0.11 | 0.36 | 0.78 | 0.23 | 0.50 | 0.15 | 0.45 | 0.82 | 0.21 | 0.57 |
| 100k | 0.16 | 0.41 | 0.82 | 0.16 | 0.54 | 0.11 | 0.36 | 0.79 | 0.23 | 0.49 | 0.15 | 0.44 | 0.82 | 0.21 | 0.57 |
| 125k | 0.15 | 0.41 | 0.82 | 0.16 | 0.54 | 0.11 | 0.37 | 0.79 | 0.23 | 0.50 | 0.15 | 0.45 | 0.82 | 0.21 | 0.57 |
| 150k | 0.15 | 0.40 | 0.82 | 0.16 | 0.53 | 0.11 | 0.35 | 0.78 | 0.23 | 0.49 | 0.15 | 0.44 | 0.82 | 0.21 | 0.57 |
| Method | Single-hop | Multi-hop | Temporal | Open-domain |
|---|---|---|---|---|
| Mistral-7B-Instruct-v0.2 | 9.1 | 15.1 | 9.3 | 8.6 |
| Llama-2-70B-chat | 20.8 | 18.2 | 15.9 | 18.8 |
| Llama-3-70B-Instruct | 17.0 | 17.0 | 12.0 | 13.0 |
| gpt-3.5-turbo-4K | 23.8 | 18.0 | 15.6 | 20.4 |
| gpt-3.5-turbo-8K | 38.5 | 25.1 | 22.7 | 25.9 |
| Ours | 25.5 | 31.3 | 38.8 | 20.4 |
| Method | Accuracy |
|---|---|
| Vanilla | 10.0 |
| RecurSum | 10.0 |
| ConditionMem | 40.0 |
| MemoryBank | 23.33 |
| Mem-PAL | 46.67 |
| Ours | 50.0 |
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