Host orchestrator for the Grid Building plugin. One Node, one _unhandled_input, one [PlacementServiceGroup]. The host owns infrastructure (input handler, mode machine) and a settings-driven service group; game-scoped [GridPlacementSettings] decide which domain services exist, and player-scoped [PlacementSession] state feeds them. The host also owns the session registry (split-screen) and intent dispatch.
Source: addons/grid_placement/systems/host/grid_placement_host.gd
Syntax
class GridPlacementHost extends Node