Ensure reconnection backoff is reset between sessions

Adjusted Log level for sse reconnection to match the actual importance of the event.

Author: nlz242

pyhilo/graphql.py

@@ -677,7 +677,7 @@ async def _drain_sse_events(
             except StopAsyncIteration:
                 break
             except asyncio.TimeoutError:
-                LOG.warning(
+                LOG.info(
                     "SSE keepalive timeout (%ss without data), reconnecting...",
                     self._SSE_KEEPALIVE_TIMEOUT,
                 )
@@ -743,6 +743,28 @@ async def _listen_to_sse(
                 )
                 await asyncio.sleep(5)
 
+            except asyncio.TimeoutError:
+                # Keepalive timeout: the connection was recently live, so start
+                # the next reconnect cycle with the base delay (not accumulated).
+                backoff_delay = self._BACKOFF_BASE
+                LOG.debug(
+                    "Reconnecting after keepalive timeout in %s seconds...",
+                    backoff_delay,
+                )
+                await asyncio.sleep(backoff_delay)
+                backoff_delay = min(backoff_delay * 2, self._BACKOFF_MAX)
+                if "query" in payload:
+                    del payload["query"]
+                if location_hilo_id:
+                    try:
+                        await self.call_get_location_query(location_hilo_id)
+                        LOG.debug("call_get_location_query success after reconnect")
+                    except Exception as e2:
+                        LOG.error(
+                            "exception while RE-connecting, retrying: %s",
+                            e2,
+                        )
+
             except Exception as e:
                 LOG.debug(
                     "Subscription connection lost: %s. Reconnecting in %s seconds...",