address review: keep arerank signature backward-compatible + defensive tests

- Restore arerank's original positional signature (prepared_request, timeout, client) and add documents/return_documents as optional kwargs, so downstream code calling arerank directly is unaffected
- Pin the three defensive scenarios reviewers raised: dict documents without a text key, non-integer index, out-of-range index. Each produces a result with only index/score and never raises.

litellm/llms/bedrock/rerank/handler.py

@@ -30,10 +30,10 @@ class BedrockRerankHandler(BaseAWSLLM):
     async def arerank(
         self,
         prepared_request: BedrockPreparedRequest,
-        documents: Sequence[str | dict[str, Any]],
-        return_documents: bool,
         timeout: float | httpx.Timeout | None = None,
         client: AsyncHTTPHandler | None = None,
+        documents: Sequence[str | dict[str, Any]] | None = None,
+        return_documents: bool = True,
     ):
         if client is None:
             client = get_async_httpx_client(llm_provider=litellm.LlmProviders.BEDROCK)

tests/test_litellm/llms/bedrock/rerank/test_bedrock_rerank_return_documents.py

@@ -165,3 +165,45 @@ async def test_bedrock_rerank_return_documents_false_async():
     assert response.results is not None
     for result in response.results:
         assert "document" not in result, f"return_documents=False must omit document, got {result}"
+
+
+def test_bedrock_rerank_dict_document_without_text_key_skips_back_fill():
+    from litellm.llms.bedrock.rerank.transformation import BedrockRerankConfig
+
+    json_documents = [
+        {"title": "zero", "body": "json zero body"},
+        {"title": "one", "body": "json one body"},
+        {"title": "two", "body": "json two body"},
+    ]
+    response = BedrockRerankConfig()._transform_response(
+        BEDROCK_RESPONSE, documents=json_documents, return_documents=True
+    )
+    assert response.results is not None
+    for result in response.results:
+        assert "document" not in result, f"dict documents without 'text' key have no back-fill target, got {result}"
+
+
+def test_bedrock_rerank_non_integer_index_skips_back_fill():
+    from litellm.llms.bedrock.rerank.transformation import BedrockRerankConfig
+
+    response = BedrockRerankConfig()._transform_response(
+        {"results": [{"index": "2", "relevanceScore": 0.9}]},
+        documents=DOCUMENTS,
+        return_documents=True,
+    )
+    assert response.results is not None
+    assert len(response.results) == 1
+    assert "document" not in response.results[0]
+
+
+def test_bedrock_rerank_out_of_range_index_skips_back_fill():
+    from litellm.llms.bedrock.rerank.transformation import BedrockRerankConfig
+
+    response = BedrockRerankConfig()._transform_response(
+        {"results": [{"index": 99, "relevanceScore": 0.9}]},
+        documents=DOCUMENTS,
+        return_documents=True,
+    )
+    assert response.results is not None
+    assert len(response.results) == 1
+    assert "document" not in response.results[0]