World Bootstrap and System Order

How to bootstrap a 6.0 world and why system ordering matters for placement correctness.

Weight: 15

System order is part of behavior in 6.0. A valid placement flow depends on validation happening before preview and execution.

Reference order

PlacementWorldSetup.add_placement_systems(world) registers:

PlacementValidationSystem
PlacementPreviewSystem
PreviewPhysicsSystem
PreviewGhostingSystem
PlacementExecutionSystem

Why this order

Validation must run before execution.
Preview should reflect current validation state.
Physics/ghosting preview effects should operate on updated preview state.

Manipulation systems

Manipulation in the demo setup is added as node-driven systems:

PlacementManipulationSystem
RemovalManipulationSystem
MovementManipulationSystem
RotationManipulationSystem

These are signal/event-driven rather than per-frame entity polling.

Sanity checks

World is non-null.
Required systems exist.
Use PlacementWorldSetup.validate_placement_world(world) to collect startup issues.