Rigid body interaction mode
There are three interaction modes between Unity rigid bodies and Truss Physics soft bodies - Kinematic, Heavy and Light.
In Kinematic mode rigid body affects soft bodies and there’s no feedback from soft bodies to rigid body. This mode is intended for big massive or kinematic rigid bodies which shouldn’t be pushed by soft bodies in any way.
In Heavy mode rigid body affects soft bodies as if it was kinematic but the reaction forces are accumulated and applied back to the rigid body on the next step. This mode works well for heavy rigid bodies with some lighter soft bodies resting on or attached to them.
In Light mode Truss Physics correctly computes the interaction between rigid and soft bodies and then corrects the position and velocity of Unity rigid body. Though the interaction computation is correct, it can sometimes break Unity simulation of constraints and collision contacts as Truss Physics is not aware of them. This mode is good for light small rigid bodies which can be easily pushed by a soft body.