The id of the AiKnowledgeBase.
OptionalnodeHard cap on returned nodes. Default 200, max 1000.
OptionaltopicRestricts the subgraph to entities under the given topic node id — any hierarchy level; an entity
matches when the topic appears anywhere in its topicPath. Unknown ids fail with
TOPIC_NOT_FOUND. Ids come from KnowledgeBaseGraphTopic.id and churn on rebuild.
Request structure for exploring a bounded subgraph of a knowledge base's graph (Phase 3 visualization). Returns the highest-degree entities and the relationships among them. Seed-based exploration (prompt/entity-name seeding + traversal depth) is a planned extension; its fields will be added here once implemented.