BUG: RealtimeTarget doesn't send its configured headers #4254

Describe the bug

RealtimeTarget takes headers (and reads OPENAI_ADDITIONAL_REQUEST_HEADERS like the other OpenAI targets), but they never reach the realtime websocket. Neither the client built in _get_openai_client nor the client.realtime.connect(...) call in _connect_async gets them, so the configured headers are left out of the websocket handshake. A realtime endpoint behind a gateway that needs its own header, like an API Management key or a routing header, can't be reached.

The other OpenAI targets pass the same headers to their client as default_headers.

Steps/Code to Reproduce

A local websocket server records the handshake headers:

import asyncio

import websockets

from pyrit.prompt_target import RealtimeTarget
from pyrit.setup import IN_MEMORY, initialize_pyrit_async

handshake_headers = {}


async def record_headers(websocket):
    handshake_headers.update({name.lower(): value for name, value in websocket.request.headers.raw_items()})
    await websocket.close()


async def main():
    await initialize_pyrit_async(memory_db_type=IN_MEMORY)
    async with websockets.serve(record_headers, "127.0.0.1", 0) as server:
        port = server.sockets[0].getsockname()[1]
        target = RealtimeTarget(
            endpoint=f"ws://127.0.0.1:{port}/v1",
            api_key="key",
            model_name="gpt-realtime",
            headers='{"X-Gateway-Key": "gateway-key"}',
        )
        connection = await target._connect_async(conversation_id="c1")
        await asyncio.sleep(0.2)
        await connection.close()

    print("authorization sent:", "authorization" in handshake_headers)
    print("x-gateway-key sent:", "x-gateway-key" in handshake_headers)


asyncio.run(main())

Expected Results

authorization sent: True
x-gateway-key sent: True

Actual Results

authorization sent: True
x-gateway-key sent: False

The client has been built this way since the move to the openai SDK in #1194. A fix is to pass them to client.realtime.connect as extra_headers, which every openai 3.x release adds to the handshake (the client's default_headers only get there in later 3.x releases, not in 3.0.0). I have it ready with a test and will open a PR.

Versions

• OS: macOS 26.4.1 (arm64)
• Python 3.13.16
• openai 3.46.0
• PyRIT main (5abca11)