fix(ollama): reasoning should come before text content (#32476)

libs/partners/ollama/langchain_ollama/_compat.py

@@ -181,12 +181,6 @@ def _convert_to_v1_from_ollama_format(response: dict[str, Any]) -> AIMessage:
     """Convert Ollama API response to AIMessage."""
     content: list[types.ContentBlock] = []
 
-    # Handle text content
-    if "message" in response and "content" in response["message"]:
-        text_content = response["message"]["content"]
-        if text_content:
-            content.append(TextContentBlock(type="text", text=text_content))
-
     # Handle reasoning content first (should come before main response)
     if "message" in response and "thinking" in response["message"]:
         thinking_content = response["message"]["thinking"]
@@ -198,6 +192,12 @@ def _convert_to_v1_from_ollama_format(response: dict[str, Any]) -> AIMessage:
                 )
             )
 
+    # Handle text content
+    if "message" in response and "content" in response["message"]:
+        text_content = response["message"]["content"]
+        if text_content:
+            content.append(TextContentBlock(type="text", text=text_content))
+
     # Handle tool calls
     if "message" in response and "tool_calls" in response["message"]:
         tool_calls = response["message"]["tool_calls"]

libs/partners/ollama/tests/unit_tests/v1/test_chat_models.py

@@ -185,6 +185,50 @@ class TestMessageConversion:
         assert result.content[0].get("text") == "Hello"
         assert result.response_metadata.get("context") == test_context
 
+    def test_reasoning_content_block_comes_before_text(self) -> None:
+        """Test that ReasoningContentBlock always comes before TextContentBlock."""
+        ollama_response = {
+            "model": MODEL_NAME,
+            "created_at": "2024-01-01T00:00:00Z",
+            "message": {
+                "role": "assistant",
+                "content": "The final answer is 4.",
+                "thinking": "Let me calculate: 2 + 2 = 4",
+            },
+            "done": True,
+            "done_reason": "stop",
+        }
+
+        result = _convert_to_v1_from_ollama_format(ollama_response)
+
+        assert isinstance(result, AIMessage)
+        assert len(result.content) == 2
+        assert result.content[0].get("type") == "reasoning"
+        assert result.content[1].get("type") == "text"
+
+    def test_reasoning_content_block_comes_before_text_in_chunks(self) -> None:
+        """Test ReasoningContentBlock comes before TextContentBlock in chunks."""
+        chunk = {
+            "model": MODEL_NAME,
+            "created_at": "2024-01-01T00:00:00Z",
+            "message": {
+                "role": "assistant",
+                "content": "The answer is 42.",
+                "thinking": "I need to think about this carefully...",
+            },
+            "done": False,
+        }
+
+        result = _convert_chunk_to_v1(chunk)
+
+        assert len(result.content) == 2
+        assert result.content[0].get("type") == "reasoning"
+        reasoning_text = "I need to think about this carefully..."
+        assert result.content[0].get("reasoning") == reasoning_text
+
+        assert result.content[1].get("type") == "text"
+        assert result.content[1].get("text") == "The answer is 42."
+
     def test_convert_empty_content(self) -> None:
         """Test converting empty content blocks."""
         message = HumanMessage(content=[])