Create a relationship between two mnemon entries. The label decides everything: its kind (containment or association) and how it reads (one_way or mutual) belong to the word itself — never send a per-edge override. All 16 labels: MEMBER (NPC ∈ Faction, mutual), ALLY (mutual), ENEMY (one-way), RIVAL (one-way), PARENT_OF (Location hierarchy — sourceEntryId is the outer/larger place, e.g. Region → City → District → Tavern), CONTAINS (Location → NPC present there), LOCATED_IN (NPC → Location; inverse of CONTAINS), HAS_SUBQUEST (Quest → subquest Quest), QUEST_GIVER (Quest → the NPC who gives it), QUEST_LOCATION (Quest → the Location where it is given or set), QUEST_RELATED_NPC (Quest → NPC), QUEST_RELATED_LOCATION (Quest → Location), SESSION_ATTENDEE_CHARACTER (SessionSummary → CHARACTER-kind Player), SESSION_ATTENDEE_NPC (SessionSummary → NPC), SESSION_FEATURED_QUEST (SessionSummary → Quest), SESSION_FEATURED_LOCATION (SessionSummary → Location). sourceEntryId is the 'from' side; targetEntryId is the 'to' side — which end is which matters. Call describe_mnemon_types for the full valid (sourceType, label, targetType) matrix. For faction membership prefer memberNpcEntryIds / affiliationEntryIds on the NPC itself; for a quest's giver, location and parent prefer giverId / locationId / parentQuestId on the quest, which keep each to one link. Session-summary links have no array equivalent — the SESSION_* labels are the only way to set them.
