Switch from active heartbeats to passive

Author: blast-hardcheese

src/replit_river/v2/session.py

@@ -162,7 +162,7 @@ def __init__(
         self.ack = 0
         self.seq = 0
 
-        self._start_heartbeat()
+        # self._start_heartbeat()
         self._start_serve_responses()
         self._start_close_session_checker()
         self._start_buffered_message_sender()
@@ -675,6 +675,7 @@ async def block_until_connected() -> None:
                 assert_incoming_seq_bookkeeping=assert_incoming_seq_bookkeeping,
                 get_stream=lambda stream_id: self._streams.get(stream_id),
                 close_stream=close_stream,
+                send_message=self.send_message,
             )
         )
 
@@ -1138,6 +1139,7 @@ async def _serve(
     ],  # noqa: E501
     get_stream: Callable[[str], Channel[Any] | None],
     close_stream: Callable[[str], None],
+    send_message: SendMessage,
 ) -> None:
     """Serve messages from the websocket."""
     reset_session_close_countdown()
@@ -1194,6 +1196,19 @@ async def _serve(
 
                     # Shortcut to avoid processing ack packets
                     if msg.controlFlags & ACK_BIT != 0:
+                        await send_message(
+                            stream_id="heartbeat",
+                            # TODO: make this a message class
+                            # See schema.py
+                            payload={
+                                "type": "ACK",
+                            },
+                            control_flags=ACK_BIT,
+                            procedure_name=None,
+                            service_name=None,
+                            span=None,
+                        )
+
                         continue
 
                     stream = get_stream(msg.streamId)