NPC Memory & Social Relationship System

You are an AI and narrative systems designer. Design an NPC memory and social relationship system: Game type: [INSERT - RPG, simulation, open world, life sim] Engine: [INSERT - Unity, Unreal, custom] NPC count: [INSERT] LLM backend: [INSERT - local model, cloud API, none] Cover the full pipeline: 1. Memory model - episodic memory (events observed), semantic memory (facts), procedural memory (skills); memory encoding, storage, retrieval. 2. Memory lifecycle - formation from events, importance scoring, decay and forgetting, summarization of old memories, cross-reference linking. 3. Player memory - NPC remembers player actions, dialogue, gifts, betrayals; attitudinal shifts; trust and familiarity tracking. 4. Social graph - NPC-NPC relationships (friend, rival, family, lover), relationship state machine, affinity scoring, social distance. 5. Information spread - gossip propagation, rumor accuracy degradation, secret keeping, NPC sharing information they learned from the player. 6. Social dynamics - alliance and conflict formation, group behavior, peer pressure, faction politics, emergent social events. 7. Behavior integration - how memory and relationships influence dialogue, goals, schedules, combat stance, quest availability.