Retaining History Is Not Maintaining State: StateCommit for Persistent World Models

Persistent world modeling under partial observability requires maintaining interaction-established states that may remain relevant after they are no longer directly observable. Existing approaches commonly preserve past interaction evidence through long context, summaries, retrieval, or recurrent memory, and reconstruct the needed state when a query or prediction is made. However, retaining evidence does not guarantee a coherent representation of what is currently true, as accurate recovery of an individual state can coexist with substantial whole-state inconsistency. To this end, we introduce StateCommit, which shifts state resolution from read time to interaction time and incrementally maintains a query-independent Active State. Specifically, interaction evidence is converted into explicit state transactions that are verified before a deterministic runtime commits persistent updates. For visual prediction, slot-indexed Visual Bindings further ground the maintained semantic state in the prediction view induced by the known next action. We also introduce StateReturn, a multimodal benchmark for whole-state maintenance and state-consistent future prediction. On StateReturn, Full-History retains 98.61% target-state accuracy after 16 intervening interactions but only 13.89% full-state exact match, whereas StateCommit achieves 98.67–100.00% full-state exact match and reduces state-sensitive prediction error by 58.1% relative to the best memory baseline. A quick visual overview of this work is available at https://statecommit.github.io/.