Question: rerank does not use index

Why does the function the RAG.rerank function does not use an index to rerank the documents?
For example, in the original paper of "colBERT" they used an already indexed documents representations in the "Top-𝑘 Re-ranking' part.
It seems more eficient and accurate to the paper.
Thanks!

Start by locating the RAG.rerank entry point and the code that builds or accesses indexed document representations. Compare the current reranking flow with the ColBERT paper's Top-k Re-ranking section. Done would require a clarified decision on whether indexed representations should be used and corresponding tests or documentation.

Written by the indexing model from the issue text.