Search based on another existing entry

It’s currently not possible to retrieve the embedding vector for an entry. My use case requires searching for context based on another existing entry. This could be addressed either by exposing the entry’s embedding vector via a new query or by allowing an entry reference to be passed directly into the search query.

Start by reviewing the existing entry retrieval and search query APIs to understand how embeddings and entry references are currently handled. Decide whether the supported behavior should expose an entry's embedding vector or accept an existing entry directly in a search query. Done means one documented, tested way to search for context based on an existing entry.

Written by the indexing model from the issue text.