Personalized LLM assistants must recover sparse evidence from long conversation histories across queries of varying complexity. We introduce APDMem (Agent-controlled Progressive Disclosure Memory), a hierarchical long-term memory architecture that applies progressive disclosure to memory retrieval. Rather than relying on a flat memory store or fixed retrieval granularity, APDMem represents conversation history as four progressively detailed layers: thematic summaries, personalized key facts, turn-level evidence notes, and raw messages. At inference time, a controller applies progressive disclosure to the memory hierarchy: it first reads high-level summaries and drills into finer evidence only when needed. This creates an adaptive cost-fidelity trade-off: simple queries can terminate early, while complex temporal, multi-hop, or exact-evidence queries trigger deeper inspection. A note synthesizer converts retrieved evidence into a query-focused structure that consolidates facts, orders events, and flags contradictions before final answer generation. Experiments on LongMemEval show that APDMem achieves strong performance for long-context memory reasoning while accessing only 8% of the total conversations.
Figures & tables
Figure 1: APDMem overview. The Multi-Resolution Memory Substrate stores conversations as layered views from thematic summaries ( L0 ) to raw messages ( L3 ). The Progressive Disclosure Controller uses tool calls to retrieve and drill down only as needed. The Organized Notes Synthesizer then consolidates collected evidence into structured notes for grounded answer generation. The upper-right panel summarizes tools available to the controller.
Backbone
Method
Temp.
Multi-S.
K-Upd.
SS-User
SS-Asst.
SS-Pref.
Avg.
GPT-4.1
Full-context ∗
51.9
39.1
70.5
65.7
96.4
16.7
56.7
Mem0 ∗
43.6
54.9
75.6
54.3
39.3
83.3
58.5
RAPTOR †
38.4
51.9
68.0
95.7
92.9
60.0
62.0
LightMem ∗
85.0
57.9
89.7
87.1
71.4
70.0
76.9
SimpleMem ∗
86.5
81.2
80.8
98.6
76.8
80.0
84.0
APDMem †
90.2
77.4
91.0
92.9
100.0
80.0
87.8
Table 1: Performance (% accuracy) on LongMemEval-S ( n=500 ). The highest value in each column is shown in bold ; the second highest is underlined .
Offline (Construction)
Online (Controller)
Method
ACC
Tok. (k)
Lat. (s)
Tok. (k)
Lat. (s)
Mem0
53.6
1,152.6
4,248.5
–
A-MEM
62.6
1,605.8
5,132.1
–
LightMem
68.6
28.3
283.8
–
APDMem
74.4
145.4
101.5
124.3
37.7
Table 2: Efficiency on LongMemEval-S (GPT-4o-mini). Offline : memory construction; Online : controller cost (cold start: no cached state for L1 & L2 ). Baselines from Fang et al. (2026) (no online numbers available).
Figure 2: Progressive disclosure behavior (GPT-4.1). (a) Retrieval selectivity: fraction of haystack sessions drilled per category. (b) Disclosure depth distribution across memory levels. (c) Error decomposition (retrieval vs. generation) for GPT-4.1-mini and GPT-4.1.
Controller
Generator
Avg. Acc. (%)
GPT-4.1-mini
GPT-4.1-mini
79.8
GPT-4.1
GPT-4.1-mini
86.8
GPT-5.2
GPT-4.1-mini
87.8
Table 3: Effect of controller backbone strength with a fixed generator on LongMemEval-S.
Configuration
Avg. Acc. (%)
Diff
APDMem
87.8
—
Vanilla RAG ( L3 -only)
77.0
↓ 12.3%
Controller ablation
w/o Controller †
83.2
↓ 5.2%
Memory hierarchy ablations
w/o read_facts ( L1 )
84.6
↓ 3.6%
Table 4: Ablation on memory hierarchy levels and reasoning tools (GPT-4.1). The “Diff” column is the percentage drop with respect to APDMem.
Appendix figures & tables7 assets
Supplementary material from the paper’s appendix.
Appendix
Module
Parameter
Value
L0
Turn window size W
4 turns
L0
Window overlap
1 turn
L0
Max chars/window
6000
L1
Max input chars
12000
L1
Bullet count
5–25
L1
Generation
On-demand
Appendix
Table 5: Hyperparameter configuration for APDMem.
Model
Median
p95
p99
Max
GPT-4.1
5
12
17
20
GPT-4.1-mini
3
12
16
19
Appendix
Table 6: Observed controller iteration statistics with Tmax=20 . The cap is reached only in rare cases, so it primarily acts as a worst-case cost and latency bound.
Method
Accuracy (%)
APDMem
87.5±1.0
SimpleMem
84.1±0.7
Appendix
Table 7: Multi-run accuracy on the full LongMemEval-S benchmark using GPT-4.1. We report mean and standard deviation over 10 independent runs. APDMem improves over SimpleMem by +3.4 percentage points on average.
Test
Type
95% CI of Δ
Statistic / Details
Welch’s t-test
Parametric
[+2.55,+4.25]
t=8.44 , p=2.6×10−7
BCa bootstrap
Non-parametric
[+2.70,+4.20]
B=10,000
Appendix
Table 8: Statistical significance analysis of the APDMem–SimpleMem accuracy gap on LongMemEval-S using GPT-4.1. Here, Δ denotes the accuracy difference between APDMem and SimpleMem in percentage points. Both confidence intervals are strictly above zero, indicating that the improvement is statistically significant.
Category
n
Agree.
κ
knowledge-update
20
0.950
0.886
multi-session
20
1.000
1.000
single-session-assistant
20
1.000
1.000
single-session-preference
20
1.000
1.000
single-session-user
20
1.000
1.000
temporal-reasoning
20
1.000
1.000
Appendix
Table 9: Human validation of the LongMemEval judge on 120 stratified question–prediction pairs.
Offline (Construction)
Online (Controller)
Model
In
Out
Tot.
In
Out
Tot.
Lat.
GPT-4o-mini
130.1
15.2
145.4
121.5
2.8
124.3
37.7s
GPT-4.1-mini
130.1
20.6
150.7
86.9
2.4
89.3
57.7s
GPT-4.1
130.1
21.2
151.3
125.3
3.2
128.5
45.9s
GPT-5.2
130.1
23.7
153.8
84.8
1.7
86.5
42.7s
Appendix
Table 10: Per-model efficiency breakdown (per-question averages, LongMemEval n=500 ). Input/output token counts and total are in thousands (k). Offline cost is identical across models except for output tokens; online cost reflects the agentic controller only.
Configuration
Avg. Acc. (%)
APDMem (full)
87.8
w/o draft answer
86.6
w/o Organized Notes
85.2
w/o Organized Notes & draft
83.6
Appendix
Table 11: Generator ablation: effect of Organized Notes and draft answer on final accuracy (GPT-4.1, fixed retrieval).