`responses` corrupts previous conversations `assistant` item

Hello. I’m not sure if I’m being daft or there is some obscure rule that I’m not aware of, or I’ve stumbled upon a bug, but here goes.

The context is as follows:

I am running an AI chat bot. Some of the messages that come from the chat bot are hard coded. I am using conversations.

The order of events is as follows.

I store a hard coded message that I sent to the user as part of the conversation so that the AI has context and is aware of the message that I sent. I use the conversations/id/items POST endpoint to store the message. I get an item_id back and the message can be seen as part of the conversation if I make a call to the conversations/id/items GET endpoint. So far so good.

If I subsequently make a call to the responses POST endpoint referencing the conversation ID, the AI response will be added to the conversation, but will corrupt the hard coded message that I just stored (and thus remove it from the conversation). If I now query the conversationds/id/items GET endpoint with the item_id of the message I stored, I get the following:

{
    "id": "msg_69f4aa450a5481969b74c76cb0147c800197e6a5b67615bf",
    "type": "message",
    "status": "completed",
    "content": [
        {
            "type": "text",
            "text": "<unknown message>"
        }
    ],
    "role": "unknown"
}

What am I missing?