> ## Documentation Index
> Fetch the complete documentation index at: https://docs.polynode.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Python Perps Stream

> Subscribe to managed Python perps tickers, BBO, full books, trades, statistics, and klines.

The V3 perps WebSocket is separate from the event and prediction-market orderbook sockets.

```python theme={null}
import asyncio
import os
from polynode import AsyncPolyNode, perps_channels

async def main() -> None:
    async with AsyncPolyNode(api_key=os.environ["POLYNODE_API_KEY"]) as pn:
        perps = pn.perps
        perps.on_reconnect(lambda notice: print("gap possible", notice))
        perps.on_overflow(lambda notice: print("local overflow", notice))

        ack = await perps.subscribe([
            perps_channels.tickers,
            perps_channels.bbo("BTC-USD"),
            perps_channels.book("BTC-USD"),
            perps_channels.trades("BTC-USD"),
            perps_channels.klines("BTC-USD", "1m"),
        ])
        if ack.rejected:
            print("rejected channels", ack.rejected)

        try:
            async for message in perps:
                if message.type == "event":
                    print(message.channel, message.data)
        finally:
            await perps.disconnect()

asyncio.run(main())
```

One subscribe request can be partially accepted. Inspect `ack.channels` and `ack.rejected`.

Each `perps_book` event is a complete replacement, not an incremental patch. `perps.book("BTC-USD")` returns the latest managed copy, or `None` until the first book event arrives. A successful acknowledgement confirms the channel, not book readiness; use the [V3 perps orderbook](/perps/market-data/book) when startup needs immediate state.

The client reconnects and resubscribes after non-terminal disconnects, but replay is not guaranteed. Reconnect notices set `gap_possible=True`; use V3 REST to backfill when completeness matters. Authentication (`4401`) and connection-limit (`4429`) closes are terminal until the failing condition changes.

See the [shared perps guide](/sdks/perps) for channel definitions, lag behavior, and lifecycle details.