PIA: A Personal Intelligence Agent Turning Health Conversations into Records and Records into Understanding
Organizations: KAIST, Republic of Korea · NAVER Corp., Seongnam, Republic of Korea · NAVER Corp., Bellevue, WA, USA
Abstract
General-purpose agent memory summarizes conversations: it extracts salient snippets, embeds them, and retrieves the top-k into the prompt. A health agent cannot run on summaries: a dose becomes a sentence, "since last week" is resolved at the model's discretion, and a three-month glucose trend cannot be answered by text similarity. We present PIA, a personal intelligence agent deployed alongside a consumer health agent. PIA receives the agent's natural-language requests, decides for itself whether and how to write or read, and turns conversations into typed clinical records and records into a synthesized understanding of the user. Its memory harness consists of four controls -- extraction, memory, retrieval, and understanding -- each a domain-agnostic mechanism with a pluggable health module: schema, medical alias dictionary, knowledge graph, and temporal rules. We show how the same query receives a different answer as the memory injected into the response context deepens from one-dimensional recall, to a two-dimensional health snapshot, to a three-dimensional trajectory with causality, and report lessons from operation: self-reported health data are missing not at random, question phrasing governs the quality of synthesized understanding, and nearly a third of candidate causal links are structural noise that rules alone remove.
Figures & tables
| Rung | What the memory knows | Status |
|---|---|---|
| 1 What | State summary | production |
| 2 Flow | Long-term user state | prod. / pilot |
| 3 Why | Causal relations | pilot |
| 4 Correction | Recommendation, follow-through | design |
| 5 What-if | Counterfactuals | design |
| Component | Metric | Value |
| Gate, RETAIN | Precision | 100.0 |
| Recall | 89.1 | |
| Accuracy | 94.9 | |
| Gate, READ | Recall | 91.0 |
| Retrieval | Tool selection | 91.0 |
| MRR | 0.785 |
Appendix figures & tables9 assets
Supplementary material from the paper’s appendix.
Appendix
| Control | Domain-agnostic mechanism | Health plug-in (what makes it a health memory) |
|---|---|---|
| Extraction | Schema-constrained extraction; temporal expressions copied verbatim, resolved deterministically; metric trajectories and event containers | 23 HUP types; intake vs. regimen, compound blood pressure, pregnancy-as-status rules; sleep-window and supply end-date arithmetic; checkup results, prescription intakes |
| Memory | Exact-alias admission gate with candidate queue; provenance and confidence per record; knowledge-graph annotation over facts | Versioned medical alias dictionary (319 terms, 4,494 aliases); reference ranges (sex-specific for 11 tests) abnormality; concept tags (condition, panel); drug indications |
| Retrieval | Read gate and router; structured retrieval by type/field; associative recall (Hindsight) + rehydration; time-ordered conflicts; hard boundary on named entities | Concept-expanded queries (“diabetes numbers” fasting glucose, HbA1c; “liver numbers” condition panel); named drugs and tests are exact |
| Understanding | Question contract over consolidated memory; synthesis over recalled memory with provenance; regeneration on record change | Seven health questions; medical-constraint field; risk-factor profile; recommendations confined to one guarded field |
| Layer | Type | What it records (representative fields) |
| Static | sex | biological sex; conditions reference ranges and sex-specific interpretation |
| age | date of birth or age; screening intervals, risk assessment | |
| height | adult height; with weight, BMI | |
| blood type | ABO/Rh | |
| allergies | confirmed drug, food, and environmental allergies; consulted before any drug or diet suggestion | |
| family history | major conditions of first-degree relatives |
| Field | Question asked of memory |
|---|---|
| who | In summary, what is this user’s current situation and what are their long-term tendencies? |
| physical_state | How is this user’s physical condition overall, and which changes or findings deserve attention now? |
| behavioral_state | What do this user’s lifestyle and behaviors look like, and which patterns within them are recurring or changing? |
| medical_constraints | What medical constraints must be kept in mind when caring for this user, and what do they mean in daily life? |
| trajectory_goal | What is this user trying to achieve, how has that goal changed over time, and how far have they come? |
| trajectory_preference | What does this user like or avoid, and how does that show in daily life? |
| Component | Model |
|---|---|
| Memory gate; read router and planner; compact normalizer and fallback; answer summary | gemma-4-26b-a4b-it |
| Associative memory: fact extraction, causal linking, consolidation | gemma-4-26b-a4b-it |
| Embeddings (retain index, semantic recall) | qwen3-embedding-4b |
| HU 2 memory reasoning (seven questions) | gemma-4-26b-a4b-it |
| Deterministic temporal resolver | no model (rules) |
| Evaluation judge (offline only) | Claude Sonnet 5 |
| Expression (as copied) | Resolution |
|---|---|
| “yesterday” | event date day |
| “three days ago, 80 kg” | event date ; value 80 kg |
| “since last Tuesday” | interval start last Tuesday before ; open end |
| “slept from 1 to 6” | sleep window 300 min; crosses midnight if start end |
| “a ten-day supply, started yesterday” | start ; expected end start 9 days |
| “last month’s checkup” | month month; day empty |
| Field | Value (active build) |
|---|---|
| standard key | test: + canonical name gongbok hyeoldang ‘fasting blood glucose’ (Hangul); unit mg/dL; category: diabetes tests; LOINC 1558-6; KOSTOM H01897515 |
| aliases | 37 rows, 18 distinct strings, e.g. gongbok hyeoldang ‘fasting blood glucose’; gongboksi hyeoldang ‘blood glucose at fasting’; sikjeon hyeoldang ‘pre-meal blood glucose’; hyeoldang (sikjeon) ‘blood glucose (pre-meal)’; FBS; Fasting blood sugar; Glucose; GLU(FBS); a legacy NLU entity name |
| reference range | one band set, all users, no age split: 100 normal; 100–125 impaired fasting glucose; 126 diabetes range (mg/dL); source: a university hospital’s public test-information page, tier T3 |
| concepts | 9 tags: test panels—diabetes tests (primary, required), metabolic-syndrome tests (primary, required), lipid tests (related); conditions—type 2 diabetes, metabolic syndrome, fatty liver, cardiovascular disease, and two further related conditions |