# prop_events.ludic — EV1 for properties: @Public promotes the structural
# attach/detach hooks to public events, so a mod sees a property appear or vanish
# on a live entity (the same shape works for @OnEnable/@OnDisable → enable/disable
# events). This extends the public-event surface past models to properties —
# "events for properties, models, scenes, layers" in the architecture.
#
# Running it prints:  300 400
program PropEvents {
  property Tag    { v: int = 0 }
  property Shield { amount: int = 0 }
  model Unit { Tag }

  @Public @OnAttach(Shield) handler Up   { }   # -> prop_Shield_attach
  @Public @OnDetach(Shield) handler Down { }   # -> prop_Shield_detach

  @On(prop_Shield_attach) handler Gained { print(entity + 300) }   # entity 0 -> 300
  @On(prop_Shield_detach) handler Lost   { print(entity + 400) }   # entity 0 -> 400

  handler Seed phase Start { spawn Unit { Tag { v: 1 } } }         # entity 0

  handler Run phase Render {
    for (u) in query [Unit]   { attach Shield on self() { amount: 5 } }   # -> prop_Shield_attach -> 300
    for (s) in query [Shield] { detach Shield on self() }                # -> prop_Shield_detach -> 400
    quit()
  }
}