[nine_k]

A great post, it starts with this:

TL;DR

• MSI’s first paper, REFRAG, is about a new way to do RAG.

• This slightly modified LLM converts most retrieved document chunks into compact, LLM-aligned chunk embeddings that the LLM can consume directly.

• A lightweight policy (trained with RL) decides which chunk embeddings should be expanded back into full tokens under a budget; the LLM runs normally on this mixed input.

• The net effect is far less KV cache and attention cost, much faster first-byte latency and higher throughput, while preserving perplexity and task accuracy in benchmarks.

I wish more long posts followed this model of a scientific paper.