Border Points: Each cluster has a limited number of defined "border points" – these are the gateways in and out of the cluster. The real magic, our Secret Sauce #1, lies in how these border points are selected. Naive approaches quickly fail:Randomly selecting border points or using simple geometric divisions (squares/hexagons) results in too many border points per cluster (50-80). The Algorithm: Ford-Fulkerson to Find the Bottlenecks To find these crucial border points, we employed a clever technique based on the Ford-Fulkerson algorithm. By cleverly identifying crucial "bottleneck" border points, creating a universal two-level hierarchy, and dynamically refining routes with our optimized A* engine, we've managed to deliver a vastly superior navigation experience.