A live coding session implementing multiple end effector support for the FABRIK inverse kinematics algorithm in the Bevy game engine using Rust. The session covers building a tree/graph structure to represent branching IK chains (Y-shaped skeletons), identifying subbases where chains meet, computing bone lengths from initial joint positions, and iterating from end effectors up to a shared root. Key challenges include grouping end effectors by their root entity, discovering subbase nodes, and designing a data structure that can later support loops for model constraints. The session also touches on Rust formatting preferences, algorithm patents (XPBD), and the conceptual nature of bones as transforms with distances rather than explicit data structures.