- Asset type 'collider' (box/circle) placed as child of a body object - 'Add collider' shortcut (hierarchy context menu + inspector) - CollisionSystem with enter/stay/exit pairs, sibling colliders excluded - Nodes: On collision enter/stay/exit, Is touching - Green outline in edit mode, hidden in play Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>