fix(vertex_ai.py): handle nested content dictionary for assistant message

openai allows the assistant content message to also be a list of dictionaries, handle that

litellm/llms/vertex_ai.py

@@ -376,17 +376,31 @@ def _gemini_convert_messages_with_history(messages: list) -> List[ContentType]:
         assistant_content = []
         ## MERGE CONSECUTIVE ASSISTANT CONTENT ##
         while msg_i < len(messages) and messages[msg_i]["role"] == "assistant":
-            assistant_text = (
+            if isinstance(messages[msg_i]["content"], list):
-                messages[msg_i].get("content") or ""
+                _parts = []
-            )  # either string or none
+                for element in messages[msg_i]["content"]:
-            if assistant_text:
+                    if isinstance(element, dict):
-                assistant_content.append(PartType(text=assistant_text))
+                        if element["type"] == "text":
-            if messages[msg_i].get(
+                            _part = PartType(text=element["text"])
+                            _parts.append(_part)
+                        elif element["type"] == "image_url":
+                            image_url = element["image_url"]["url"]
+                            _part = _process_gemini_image(image_url=image_url)
+                            _parts.append(_part)  # type: ignore
+                assistant_content.extend(_parts)
+            elif messages[msg_i].get(
                 "tool_calls", []
             ):  # support assistant tool invoke convertion
                 assistant_content.extend(
                     convert_to_gemini_tool_call_invoke(messages[msg_i]["tool_calls"])
                 )
+            else:
+                assistant_text = (
+                    messages[msg_i].get("content") or ""
+                )  # either string or none
+                if assistant_text:
+                    assistant_content.append(PartType(text=assistant_text))
+
             msg_i += 1
 
         if assistant_content:

litellm/tests/test_amazing_vertex_completion.py

@@ -975,3 +975,27 @@ def test_prompt_factory():
     translated_messages = _gemini_convert_messages_with_history(messages=messages)
 
     print(f"\n\ntranslated_messages: {translated_messages}\ntranslated_messages")
+
+
+def test_prompt_factory_nested():
+    messages = [
+        {"role": "user", "content": [{"type": "text", "text": "hi"}]},
+        {
+            "role": "assistant",
+            "content": [
+                {"type": "text", "text": "Hi! 👋 \n\nHow can I help you today? 😊 \n"}
+            ],
+        },
+        {"role": "user", "content": [{"type": "text", "text": "hi 2nd time"}]},
+    ]
+
+    translated_messages = _gemini_convert_messages_with_history(messages=messages)
+
+    print(f"\n\ntranslated_messages: {translated_messages}\ntranslated_messages")
+
+    for message in translated_messages:
+        assert len(message["parts"]) == 1
+        assert "text" in message["parts"][0], "Missing 'text' from 'parts'"
+        assert isinstance(
+            message["parts"][0]["text"], str
+        ), "'text' value not a string."