Fixed-base two-link articulation

Multi-prim test composition: a two-link reduced-coordinate articulation. /World/Base and /World/Link are Cube rigid bodies one unit apart joined by /World/Hinge, a PhysicsRevoluteJoint with body0 the parent (Base) so no sign flip applies to drive and state. /World/RootJoint is a PhysicsFixedJoint with only body1 (Base) authored, so body0 is the world; it carries PhysicsArticulationRootAPI and PhysxArticulationAPI and, being a joint to world, is elected root: the runtime sets PxArticulationFlag::eFIX_BASE and creates no PxJoint for it. The articulation is observed on the root-API prim. The hinge is verified through the articulation joint (PhysxJointAPI, PhysxJointAxisAPI, PhysicsJointStateAPI, PhysxDrivePerformanceEnvelopeAPI columns); its standalone PxJoint columns are unobservable here (NaN on both sides). Owns no columns and generates no helper.

• Form: multi-prim; no helper, the contract test builds each prim with PrimBatch.

Path	Type	Applied APIs	Authored values	Relationships	Verified
/World/Base	Cube	PhysicsRigidBodyAPI, PhysicsCollisionAPI	size		no
/World/Link	Cube	PhysicsRigidBodyAPI, PhysicsCollisionAPI	size, omni:xform		no
/World/RootJoint	PhysicsFixedJoint	PhysicsArticulationRootAPI, PhysxArticulationAPI		physics:body1 -> /World/Base	yes
/World/Hinge	PhysicsRevoluteJoint	PhysxJointAPI, PhysicsDriveAPI:angular, PhysxJointAxisAPI:angular, PhysicsJointStateAPI:angular, PhysxDrivePerformanceEnvelopeAPI:angular	physics:localPos0, physics:localPos1	physics:body0 -> /World/Base, physics:body1 -> /World/Link	yes