1  from __future__ import annotations
 2  
 3  from typing import Protocol
 4  
 5  from langchain_core.documents import Document
 6  
 7  
 8  class Reranker(Protocol):
 9      """Protocol for document reranking backends."""
10  
11      def rerank(
12          self, query: str, documents: list[tuple[Document, float]]
13      ) -> list[tuple[Document, float]]:
14          """Rerank documents based on relevance to the query.
15  
16          Parameters
17          ----------
18          query
19              User's search query
20          documents
21              List of (Document, score) tuples from initial retrieval
22  
23          Returns
24          -------
25          List of (Document, score) tuples reordered by relevance with new scores
26          """
27          ...