Called once before the streaming loop. Deletes stale vector store entries for all files that will be re-chunked (toProcess) or removed (toDelete). On force mode or vector-store change, deletes all tracked source files.
Optional
Upload a batch of embedded chunks to the vector store, then mark them uploaded and clear the embedding BLOB to reclaim storage.
Called once before the streaming loop. Deletes stale vector store entries for all files that will be re-chunked (toProcess) or removed (toDelete). On force mode or vector-store change, deletes all tracked source files.