LabEngine-Chem: Flux-Based Grounding of Symbolic Chemistry in Embodied Worlds

Autonomous laboratories require physical execution and chemical evolution to describe a single causally consistent experimental world. However, existing symbolic chemistry environments typically update chemical states from commanded actions, while embodied laboratory simulators often couple physics and chemistry through simulator-specific events or terminal outcomes. Such interfaces can obscure execution errors and discard the temporal structure of physical processes. We introduce ChemWorld, a conservative synchronization framework that grounds symbolic chemical dynamics in the realized consequences of embodied execution. ChemWorld represents physical–chemical interaction through continuous material, heat, and phase fluxes, together with mixing state, and commits all updates through a single conservative world integrator. Chemistry therefore evolves from what was physically transferred or exchanged rather than from what an agent intended to do, while the resulting state is projected back into observable quantities such as spectra, RGB appearance, temperature, turbidity, pressure, and phase composition. We show that this distinction materially affects both chemical trajectories and agent evaluation: terminal-event coupling incurs a 0.00797 mol product-trajectory error for a 10 s pour, while across 200 paired physical cases symbolic execution yields 100.0% open-loop success compared with 54.5% under embodied execution. Grounded observations and corrective actions recover performance to 66.5%, and improve held-out composed perturbations from 11.0% to 31.5%. The same synchronization abstraction supports multiple chemistry backends and extends to liquid, solid, and gas processes, providing an execution-grounded interface for evaluating autonomous laboratory agents in physically consequential experimental worlds.