The useful boundary in IPC Toolkit is clear: it provides contact routines, while the calling simulation owns time stepping and solving.
The toolkit includes barrier functions and derivatives, adaptive barrier stiffness, broad- and narrow-phase continuous collision detection, distance derivatives for edges and triangles, distance barrier potentials, and smooth or lagged dissipative friction potentials.
That list also describes the limit. IPC Toolkit is not a complete physics engine and does not include a simulation loop or solver. The upstream project points to PolyFEM and Rigid IPC as full simulation implementations that use it.
My project note keeps the repository overview with the other project documentation. The upstream README and contributor fork are the references for build details and current changes.