Add POST /api/conversations/{id}/message endpoint (#11177)

Co-authored-by: openhands <openhands@all-hands.dev>

openhands/server/routes/conversation.py

@@ -3,6 +3,7 @@ from fastapi.responses import JSONResponse
 from pydantic import BaseModel
 
 from openhands.core.logger import openhands_logger as logger
+from openhands.events.action.message import MessageAction
 from openhands.events.event_filter import EventFilter
 from openhands.events.event_store import EventStore
 from openhands.events.serialization.event import event_to_dict
@@ -177,6 +178,53 @@ async def add_event(
     return JSONResponse({'success': True})
 
 
+class AddMessageRequest(BaseModel):
+    """Request model for adding a message to a conversation."""
+
+    message: str
+
+
+@app.post('/message')
+async def add_message(
+    data: AddMessageRequest,
+    conversation: ServerConversation = Depends(get_conversation),
+):
+    """Add a message to an existing conversation.
+
+    This endpoint allows adding a user message to an existing conversation.
+    The message will be processed by the agent in the conversation.
+
+    Args:
+        data: The request data containing the message text
+        conversation: The conversation to add the message to (injected by dependency)
+
+    Returns:
+        JSONResponse: A JSON response indicating the success of the operation
+    """
+    try:
+        # Create a MessageAction from the provided message text
+        message_action = MessageAction(content=data.message)
+
+        # Convert the action to a dictionary for sending to the conversation
+        message_data = event_to_dict(message_action)
+
+        # Send the message to the conversation
+        await conversation_manager.send_event_to_conversation(
+            conversation.sid, message_data
+        )
+
+        return JSONResponse({'success': True})
+    except Exception as e:
+        logger.error(f'Error adding message to conversation: {e}')
+        return JSONResponse(
+            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+            content={
+                'success': False,
+                'error': f'Error adding message to conversation: {e}',
+            },
+        )
+
+
 class MicroagentResponse(BaseModel):
     """Response model for microagents endpoint."""
 

tests/unit/server/routes/test_conversation_routes.py

@@ -8,7 +8,11 @@ from fastapi.responses import JSONResponse
 
 from openhands.microagent.microagent import KnowledgeMicroagent, RepoMicroagent
 from openhands.microagent.types import MicroagentMetadata, MicroagentType
-from openhands.server.routes.conversation import get_microagents
+from openhands.server.routes.conversation import (
+    AddMessageRequest,
+    add_message,
+    get_microagents,
+)
 from openhands.server.routes.manage_conversations import (
     UpdateConversationRequest,
     update_conversation,
@@ -619,3 +623,112 @@ async def test_update_conversation_no_user_id_no_metadata_user_id():
         # Verify success (should work when both are None)
         assert result is True
         mock_conversation_store.save_metadata.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_add_message_success():
+    """Test successful message addition to conversation."""
+    # Create a mock ServerConversation
+    mock_conversation = MagicMock(spec=ServerConversation)
+    mock_conversation.sid = 'test_conversation_123'
+
+    # Create message request
+    message_request = AddMessageRequest(message='Hello, this is a test message!')
+
+    # Mock the conversation manager
+    with patch(
+        'openhands.server.routes.conversation.conversation_manager'
+    ) as mock_manager:
+        mock_manager.send_event_to_conversation = AsyncMock()
+
+        # Call the function directly
+        response = await add_message(
+            data=message_request, conversation=mock_conversation
+        )
+
+        # Verify the response
+        assert isinstance(response, JSONResponse)
+        assert response.status_code == 200
+
+        # Parse the JSON content
+        content = json.loads(response.body)
+        assert content['success'] is True
+
+        # Verify that send_event_to_conversation was called
+        mock_manager.send_event_to_conversation.assert_called_once()
+        call_args = mock_manager.send_event_to_conversation.call_args
+        assert call_args[0][0] == 'test_conversation_123'  # conversation ID
+
+        # Verify the message data structure
+        message_data = call_args[0][1]
+        assert message_data['action'] == 'message'
+        assert message_data['args']['content'] == 'Hello, this is a test message!'
+
+
+@pytest.mark.asyncio
+async def test_add_message_conversation_manager_error():
+    """Test add_message when conversation manager raises an exception."""
+    # Create a mock ServerConversation
+    mock_conversation = MagicMock(spec=ServerConversation)
+    mock_conversation.sid = 'test_conversation_123'
+
+    # Create message request
+    message_request = AddMessageRequest(message='Test message')
+
+    # Mock the conversation manager to raise an exception
+    with patch(
+        'openhands.server.routes.conversation.conversation_manager'
+    ) as mock_manager:
+        mock_manager.send_event_to_conversation = AsyncMock(
+            side_effect=Exception('Conversation manager error')
+        )
+
+        # Call the function directly
+        response = await add_message(
+            data=message_request, conversation=mock_conversation
+        )
+
+        # Verify the response
+        assert isinstance(response, JSONResponse)
+        assert response.status_code == 500
+
+        # Parse the JSON content
+        content = json.loads(response.body)
+        assert content['success'] is False
+        assert 'Conversation manager error' in content['error']
+
+
+@pytest.mark.asyncio
+async def test_add_message_empty_message():
+    """Test add_message with an empty message."""
+    # Create a mock ServerConversation
+    mock_conversation = MagicMock(spec=ServerConversation)
+    mock_conversation.sid = 'test_conversation_123'
+
+    # Create message request with empty message
+    message_request = AddMessageRequest(message='')
+
+    # Mock the conversation manager
+    with patch(
+        'openhands.server.routes.conversation.conversation_manager'
+    ) as mock_manager:
+        mock_manager.send_event_to_conversation = AsyncMock()
+
+        # Call the function directly
+        response = await add_message(
+            data=message_request, conversation=mock_conversation
+        )
+
+        # Verify the response
+        assert isinstance(response, JSONResponse)
+        assert response.status_code == 200
+
+        # Parse the JSON content
+        content = json.loads(response.body)
+        assert content['success'] is True
+
+        # Verify that send_event_to_conversation was called with empty content
+        mock_manager.send_event_to_conversation.assert_called_once()
+        call_args = mock_manager.send_event_to_conversation.call_args
+        message_data = call_args[0][1]
+        assert message_data['args']['content'] == ''