Contact as Interface: Composing Object-Centric Interactions with Executor-Aware Fields for Long-Horizon Pushing

Long-horizon planar pushing in clutter faces two coupled challenges: collision-free object paths may require contacts that a robot cannot realize, and uncertain interaction dynamics can cause deviations from planned motions. We present Contact as Interface (CaI), a framework for long-horizon pushing that connects object-level planning and embodiment-specific execution through a reusable contact interface. An inverse interaction policy implements this interface by mapping normalized object geometry and local motion intents to contact actions. We learn this local mapping using only isolated pushes generated automatically in simulation, without complete task demonstrations, and keep the resulting policy fixed across downstream tasks. Deployment requires no object-specific dynamics identification. Executor-aware cost-to-go fields combine object-space reachability with direction-dependent execution costs to guide both nominal path construction and corrective intent search. An embodiment-specific executor selects and executes feasible contact actions. When progress stalls or repeated attempts fail to find feasible contact actions for the current intent, feedback-driven recovery searches for alternative motion intents. On two benchmarks we construct, CaI achieves 82.29% success in coupled local pose control on held-out geometries and 89.29% overall success in long-horizon pushing, exceeding the success rates of the evaluated baselines. Further experiments demonstrate robustness to nonuniform mass distributions, cross-embodiment reuse, and direct sim-to-real transfer without policy fine-tuning. These results show that a fixed local interaction policy can support long-horizon pushing in clutter when object-level planning accounts for robot feasibility and motion intents are adapted in response to observed deviations in object motion.