7.1 The ai and realm namespaces are reserved

Any property or function in the ai namespace — the bare ai key, the flat ai_* prefix, or the ai.* function form — is an engine primitive, never data, and the bare realm key is likewise reserved (§7.2.2). A realm MUST NOT declare a stored property or a producer field named ai, ai_*, or realm; the graph schema is open and realm-defined, so the reservation is what keeps the primitives collision-free and self-documenting to the generator. ai.relevant and ai.score are “fake” functions: they carry no stored value — the engine computes them for the rows a query touches and, having computed them, writes the result onto the transient row as real data so ordinary Cypher (WHERE, ORDER BY) can read it. They are defined only over fetched / materialized rows (a virtual join’s targets, §2) — the judgment is what the source could not express — so anchor them on a virtual collection, not a raw persisted label.