fix: reconnect after silent control heartbeat loss

src/archive_clients/daemon.py

@@ -11,6 +11,7 @@ from pathlib import Path, PurePosixPath
 from typing import Any
 
 from websockets.asyncio.client import connect
+from websockets.exceptions import ConnectionClosedOK
 
 from archive_clients.backup import SQLiteBackupManager
 from archive_clients.config import ClientConfig
@@ -205,7 +206,23 @@ class ArchiveClientDaemon:
             command_tasks: set[asyncio.Task[None]] = set()
             try:
                 await self._resume_commands(outbound, command_tasks)
-                async for frame in websocket:
+                # A proxy can leave the TCP/WebSocket socket apparently open
+                # after the control server has discarded its session.  The
+                # server then cannot deliver durable commands and its pending
+                # outbox remains stranded unless the client independently
+                # detects the missing application heartbeats and reconnects.
+                while True:
+                    try:
+                        frame = await asyncio.wait_for(
+                            websocket.recv(),
+                            self.config.connection.offline_timeout,
+                        )
+                    except ConnectionClosedOK:
+                        return
+                    except asyncio.TimeoutError as exc:
+                        raise RuntimeError(
+                            "control heartbeat timed out"
+                        ) from exc
                     await self._handle(decode(frame), outbound, command_tasks)
             finally:
                 writer.cancel()