Probabilistic Simulation of Single-Entity Systems in Irregular Time R package fluxCore version 2.1.0 A foundation for probabilistic simulation of single-entity systems in which events occur at irregular times and each event updates only a small, sparse subset of the entity's state. Models are assembled from a declared schema and a bundle of callback functions for event proposal, state transition, and stopping, with their contracts validated before simulation. Supports competing event processes, schema-declared decision points with user-supplied policies, typed parameter draws for representing uncertainty, and optional trajectory recording for auditing simulated decisions. Designed to be domain agnostic: this package contains no model of any particular system, only the scaffolding for building one. Software Imports: R6 Suggests: future, future.apply, jsonlite, parallel, testthat (>= 3.0.0) Jarrod Dalton <daltonj@ccf.org> Comprehensive R Archive Network (CRAN) Jarrod Dalton [aut, cre] LGPL-3 2026-09-22 application/tgz https://CRAN.R-project.org/package=fluxCore doi:10.32614/CRAN.package.fluxCore