ludic/docs/language/scenes/kw-enter.md

id	name	category	kind	tokens	sig	tip	order
kw-enter	enter	scenes	keyword	enter	on enter { … }	The scene-entry hook — runs once as a scene becomes active.	3

enter names the body of a scene's entry hook, written on enter { … }. It runs once each time the scene becomes active — at boot for the start scene (right after the Start phase), and on every become Name that switches into it. This is where a scene builds what it owns: spawn its models, reset its counters, set the tilemap, open a menu. It is a lifecycle hook, not a phase, so it may not contain phase handlers; the scene's ongoing behaviour goes in its layer handlers instead.

program EnterHookExample {
  property Position { column: int = 0, row: int = 0 }
  model Player { Position }

  state EnterHookExampleState {
    score: int = 0
  }

  scene Overworld start {
    on enter (enter_hook_example_st: mut EnterHookExampleState) {
      enter_hook_example_st.score = 0
      spawn Player { Position { column: 5, row: 5 } }
    }
    layer World {
      handler DrawWorld phase Render {
        Screen.clear(Color.MidnightBlue)
        for (current_position) in query [Position, {Player}] {
          Screen.fill_rectangle(x: current_position.column * 16, y: current_position.row * 16, width: 16, height: 16, color: Color.LimeGreen)
        }
        Screen.show()
      }
    }
  }
}