fix: better bedrock message handler close langgenius#10976

Signed-off-by: yihong0618 <[email protected]>

Author: yihong0618

api/core/model_runtime/model_providers/bedrock/llm/llm.py

@@ -194,6 +194,16 @@ def _generate_with_converse(
         if model_info["support_tool_use"] and tools:
             parameters["toolConfig"] = self._convert_converse_tool_config(tools=tools)
         try:
+            # for issue #10976
+            # add placeholder for conversation because that bedrock-runtime doesn't support two users
+            # FIXME: when bedrock-runtime support two users, we should remove this placeholder
+            conversations_list = parameters["messages"]
+            # if two roles next to each other, insert a placeholder('role': 'assistant') for conversation
+            for i in range(len(conversations_list) - 1):
+                if conversations_list[i]["role"] == "user" and conversations_list[i + 1]["role"] == "user":
+                    # insert a placeholder for assistant and it can not be empty string
+                    conversations_list.insert(i + 1, {"role": "assistant", "content": [{"text": "placeholder"}]})
+
             if stream:
                 response = bedrock_client.converse_stream(**parameters)
                 return self._handle_converse_stream_response(