OpenAI Assistants API v2: Should I attach files to the thread or to the assistant?

I am using the OpenAI Assistants API, and I have the option to add my PDF files as a knowledge base.

Should I attach files to the thread or to the assistant?

I am super confused here.

Or should I add them both times?

What would work best?

When using the OpenAI Assistants API v2, you attach files when you add a user message to the thread by using the attachments parameter.

In the code examples below, I passed a file with the file_search tool.

Python:

my_thread_message = client.beta.threads.messages.create(
    thread_id=my_thread.id,
    role="user",
    content=user_input,
    attachments=[  # 👈 Add files by using the attachments parameter
        {"file_id": file_id, "tools": [{"type": "file_search"}]}
    ],
)

Node.js:

const myThreadMessage = await openai.beta.threads.messages.create(
  (thread_id = myThread.id),
  {
    role: "user",
    content: userInput,
    attachments: [ // 👈 Add files by using the attachments parameter
      {
        file_id: fileID,
        tools: [{ type: "file_search" }],
      },
    ],
  }
);