# NPC Simulation Tier State Machine — D-026
# bevy_ecs dynamic component add/remove makes tier transitions seamless.
# Scope tags keep NPCs in Active tier.

vars: {
  color-bg: "#2a3040"
  color-stroke: "#333340"
  color-text: "#c8d0e0"
  color-accent: "#c8d8f0"
  color-dim: "#1a1e24"
}

ungenerated: Tier 4\nUngenerated {
  style.fill: ${color-dim}
  style.stroke: ${color-stroke}
  style.font-color: ${color-text}
  style.stroke-dash: 5
}

state_saved: Tier 3\nState-Saved\n~1-2KB frozen struct {
  style.fill: ${color-bg}
  style.stroke: ${color-stroke}
  style.font-color: ${color-text}
}

background: Tier 2\nBackground\n500-2,000 NPCs {
  style.fill: ${color-bg}
  style.stroke: ${color-stroke}
  style.font-color: ${color-text}
}

active: Tier 1\nActive\n30-80 NPCs · full sim {
  style.fill: ${color-bg}
  style.stroke: ${color-accent}
  style.font-color: ${color-text}
  style.bold: true
}

scope_tags: Scope Tags (prevent eviction) {
  shape: package
  style.fill: ${color-dim}
  style.stroke: ${color-accent}
  style.font-color: ${color-text}

  neighborhood: neighborhood {
    style.fill: ${color-bg}
    style.stroke: ${color-stroke}
    style.font-color: ${color-text}
  }
  active_quest: active-quest {
    style.fill: ${color-bg}
    style.stroke: ${color-stroke}
    style.font-color: ${color-text}
  }
  colleague: colleague {
    style.fill: ${color-bg}
    style.stroke: ${color-stroke}
    style.font-color: ${color-text}
  }
  known_contact: known-contact {
    style.fill: ${color-bg}
    style.stroke: ${color-stroke}
    style.font-color: ${color-text}
  }
}

lru: LRU Priority Queue\n(interaction-timestamp) {
  shape: diamond
  style.fill: ${color-bg}
  style.stroke: ${color-accent}
  style.font-color: ${color-text}
}

ungenerated -> state_saved: "player approach\n(generated ahead)" {
  style.stroke: ${color-stroke}
}
state_saved -> background: "player return\n(~2-5ms reactivation)" {
  style.stroke: ${color-stroke}
}
background -> state_saved: "LRU eviction" {
  style.stroke: ${color-stroke}
  style.stroke-dash: 4
}
background -> active: "player proximity\nor scope tag match" {
  style.stroke: ${color-accent}
}
active -> background: "LRU eviction\n(no scope tag)" {
  style.stroke: ${color-stroke}
  style.stroke-dash: 4
}
scope_tags -> active: "prevents eviction" {
  style.stroke: ${color-accent}
  style.stroke-dash: 4
}
lru -> active: "manages" { style.stroke: ${color-accent} }
lru -> background: "manages" { style.stroke: ${color-stroke} }