The same-length fake/Qwen comparison is the strongest part of the constructor argument: a plausible score can hide an incompatible coordinate system. If this store later becomes persistent, I would carry an embedding specification with it, including the model revision, dimensions, and query/document preprocessing, and validate that specification when opening the stored collection.

Handing the store one embedder prevents two local construction sites from disagreeing, but it cannot by itself detect an existing collection created under another configuration. A focused test could reopen a collection with a different model specification of the same dimension and require a clear failure before any search runs. That extends the invariant without enlarging the retriever's interface.