Ghost improvements

from dataclasses import dataclass, field
from enum import Enum, auto

class Intent(Enum):
    THREAT = auto()
    FRIENDLY = auto()
    NEUTRAL = auto()

@dataclass(frozen = True)
class Signal:
    source: str
    intent: Intent
    actor: str
    intensity: float  # 0.0 to 1.0

@dataclass
class NPCState:
    threat_level: float = 0.0

    def apply(self, signal: Signal) -> "NPCState":
        """Returns a new state with the signal applied (immutable style)."""
        match signal.intent:
            case Intent.THREAT:
                return NPCState(threat_level=min(1.0, self.threat_level + signal.intensity * 0.1))
            case Intent.FRIENDLY:
                return NPCState(threat_level=max(0.0, self.threat_level - signal.intensity * 0.05))
            case _:
                return self

# Usage - no global state, explicit ownership
npc = NPCState()
for _ in range(5):
    signal = Signal(source="npc_engine", intent=Intent.THREAT, actor="player", intensity=0.5)
    npc = npc.apply(signal)
    print(npc.threat_level)