Context and typed sets

NodalContext owns a model, provider, identity map, change tracker, and database facade. Public set properties make the graph vocabulary explicit:

public GraphSet<Person> People => Set<Person>();

public RelationSet<Person, Knows, Person> Friendships =>
    Relations<Person, Knows, Person>();

GraphSet<TNode> begins node queries and tracks node mutations. RelationSet<TSource, TRelation, TTarget> preserves the source, relationship payload, and target types for traversal and changes. The relation is not reduced to a foreign key; it remains a domain object.

Keep providers long-lived. Neo4j's provider owns a pooled driver, while TigerGraph accepts an externally managed HttpClient so the host controls handler lifetime and HTTP pooling.