[Bounty] Update Dr. Agent model (PyHealth 2.0)

[joshuasteier]

Contributor

• Name: Joshua Steier

Contribution Type

Model

Description

Implements the Dr. Agent model from "Dr. Agent: Clinical predictive model via mimicked second opinions" (JAMIA 2020).

Key features:

• Dual-agent reinforcement learning with dynamic skip connections
• Primary agent (current visit) + second-opinion agent (historical context)
• Support for static demographic features
• GRU/LSTM cell options
• REINFORCE with optional baseline for variance reduction

Paper: https://doi.org/10.1093/jamia/ocaa074

Files to Review

File	Description
pyhealth/models/agent.py	Model implementation (AgentLayer + Agent)
tests/test_agent.py	Unit tests
examples/agent_mimic4.ipynb	Example notebook with MIMIC-IV

How to Test

# Run unit tests
python -m pytest tests/test_agent.py -v

# Or run the model directly
python pyhealth/models/agent.py

Checklist

• [x] Code follows PEP8 (88-char line limit)
• [x] Google-style docstrings with type hints
• [x] Inherits from BaseModel (v2.0 style)
• [x] Unit tests provided
• [x] Example notebook provided
• [x] Rebased with main branch