In September 2025, this developer contributed to the jrouwe/JoltPhysics repository by exporting the IslandBuilder API to support custom physics constraints. Using C++ and leveraging expertise in library development and physics simulation, they enabled user code to create new constraints that affect island behavior within the physics engine. The API design closely followed the established VehicleConstraint::BuildIslands pattern, ensuring consistent semantics for island-building across different constraint types. This work enhanced the extensibility of JoltPhysics, allowing for greater user-driven customization of physics behavior. The contribution demonstrated a focused, in-depth approach to API design and extensibility within a complex simulation framework.