fix(factory.py): Add reasoning content handling for missing assistant… (#10688)

* fix(factory.py): Add reasoning content handling for missing assistant content

* fix(factory.py): Improve handling of thinking blocks for assistant content

* test(factory.py): Add test for Bedrock processing of thinking blocks with None content

Author: LouisShark

litellm/litellm_core_utils/prompt_templates/factory.py

@@ -3040,6 +3040,19 @@ async def _bedrock_converse_messages_pt_async(  # noqa: PLR0915
                     )
                 )
                 _assistant_content = assistant_message_block.get("content", None)
+                thinking_blocks = cast(
+                    Optional[List[ChatCompletionThinkingBlock]],
+                    assistant_message_block.get("thinking_blocks"),
+                )
+
+                if thinking_blocks is not None:
+                    converted_thinking_blocks = BedrockConverseMessagesProcessor.translate_thinking_blocks_to_reasoning_content_blocks(
+                        thinking_blocks
+                    )
+                    assistant_content = BedrockConverseMessagesProcessor.add_thinking_blocks_to_assistant_content(
+                        thinking_blocks=converted_thinking_blocks,
+                        assistant_parts=assistant_content,
+                    )
 
                 if _assistant_content is not None and isinstance(
                     _assistant_content, list
@@ -3053,7 +3066,10 @@ async def _bedrock_converse_messages_pt_async(  # noqa: PLR0915
                                         cast(ChatCompletionThinkingBlock, element)
                                     ]
                                 )
-                                assistants_parts.extend(thinking_block)
+                                assistants_parts = BedrockConverseMessagesProcessor.add_thinking_blocks_to_assistant_content(
+                                    thinking_blocks=thinking_block,
+                                    assistant_parts=assistants_parts,
+                                )
                             elif element["type"] == "text":
                                 assistants_part = BedrockContentBlock(
                                     text=element["text"]

tests/litellm/litellm_core_utils/prompt_templates/test_litellm_core_utils_prompt_templates_factory.py

@@ -7,9 +7,9 @@
 from litellm.litellm_core_utils.prompt_templates.factory import (
     BAD_MESSAGE_ERROR_STR,
     ollama_pt,
+    BedrockConverseMessagesProcessor,
 )
 
-
 def test_ollama_pt_simple_messages():
     """Test basic functionality with simple text messages"""
     messages = [
@@ -43,6 +43,41 @@ def test_ollama_pt_consecutive_user_messages():
     assert isinstance(result, dict)
     assert result["prompt"] == expected_prompt
 
+@pytest.mark.asyncio
+async def test_anthropic_bedrock_thinking_blocks_with_none_content():
+    """
+    Test the specific function that processes thinking_blocks when content is None
+    """
+    mock_assistant_message = {
+        "content": "None",  # content is None
+        "role": "assistant",
+        "thinking_blocks": [
+            {
+                "type": "thinking",
+                "thinking": "This is a test thinking block",
+                "signature": "test-signature"
+            }
+        ],
+        "reasoning_content": "This is the reasoning content"
+    }
+    messages = [
+        {"role": "user", "content": "What is the capital of France?"},
+        mock_assistant_message
+    ]
+
+    # test _bedrock_converse_messages_pt_async
+    result = await BedrockConverseMessagesProcessor._bedrock_converse_messages_pt_async(
+        messages=messages,
+        model="us.anthropic.claude-3-7-sonnet-20250219-v1:0",
+        llm_provider="bedrock"
+    )
+
+
+    # verify the result
+    assert len(result) == 2
+    assert result[1]["content"][0]["reasoningContent"]["reasoningText"]["text"] == "This is a test thinking block"
+
+
 
 # def test_ollama_pt_consecutive_system_messages():
 #     """Test handling consecutive system messages"""