```python
from fastapi import FastAPI
from fastapi.responses import JSONResponse
from starlette.concurrency import run_in_threadpool

import helpers  # noqa: F401  (the provided API)

app = FastAPI()


@app.post("/orders")
async def create_order(payload: dict):
    item = payload.get("item")
    await run_in_threadpool(helpers.append_audit_line, f"order:{item}")
    return JSONResponse(content={"status": "created"}, status_code=201)
```