embedder

Embedder.identity of the model that produced embedding.

Without it an entry says what it means but not what measured it, and a cache that swapped models would go on scoring old vectors against new ones in a space they do not share. A SemanticCache stamps this on every write and refuses, on lookup, any entry that does not carry its own.

A store that persists entries must round-trip it. One rehydrated without it reads as Embedder.UNDECLARED, which is correct for everything written before identities existed: nobody can say what wrote those, and undeclared is exactly that statement.