Fit Cox proportional hazards relational event models (REMs),
including a separable formulation that partitions events into initiation
and continuation sub-models. Optionally augments REM simulations with
large language model (LLM) agents that select targets conditioned on
event history, supporting multiple providers ('OpenAI', 'Anthropic',
'xAI'/'Grok', 'Google Gemini', 'Ollama', 'AWS Bedrock') through a common
interface. See Butts (2008)