$MARC$: MECHANISM-AWARE REFLECTIVE CORRECTION FOR ARTICULATED OBJECT CODE GENERATION

Generating functional articulated objects requires geometry, connectivity, and motion to agree. This is particularly challenging for mechanisms with coupled motion and closed kinematic chains: plausible parts and joints can still form disconnected linkages, immobile assemblies, or motions that violate the intended structure. We present $MARC$, a kinematic-graph-centered agent harness for generating executable articulated-object programs from visual and textual specifications. The harness organizes construction, numerical execution, and revision around a shared representation of rigid parts, connection interfaces, joints, and coupling constraints. Explicit constraints beyond the joint tree allow a solver to assemble the mechanism and recover coupled motion, including nonlinear dependencies between driver and follower joints. Structural and motion evaluation then grounds model-driven revisions of the graph, interfaces, and geometry in the resulting execution evidence. By connecting structural decisions to their consequences over motion, MARC makes mechanism generation an iterative process of proposing, testing, and revising executable constraints.