stabilize app shutdown flow and resource cleanup

backend/src/app.py

@@ -4,6 +4,7 @@ import json
 import time
 import sys
 import os
+import signal
 
 from tortoise import Tortoise
 from tortoise.expressions import Q
@@ -28,6 +29,8 @@ class App(ChatMixin):
         self.remote_connections = {}
         self.streams = {}
         self.event_listeners = []
+        # active websocket tasks, for manual cancelling upon server shutdown
+        self.ws_tasks = []
 
         self.tmp = tmp.State()
 
@@ -380,12 +383,29 @@ async def main():
     )
 
     # 3. Start Server
-    # Note: start_server must be an async function or handle an event loop
-    await start_server(horde_app)
+    # manually trigger server shutdown, avoids hypercorn installing signal handlers
+    shutdown_event = asyncio.Event()
+    server_task = asyncio.create_task(start_server(horde_app, shutdown_event))
+
+    # 4. Graceful Termination
+    loop = asyncio.get_running_loop()
+    def interrupt():
+        print("Interrupt Signal")
+        shutdown_event.set()
+        # Unblock websocket handlers parked in websocket.receive()
+        for task in list(horde_app.ws_tasks):
+            task.cancel()
+
+    for sig in (signal.SIGINT, signal.SIGTERM):
+        loop.add_signal_handler(sig, interrupt)
+
+    try:
+        await server_task
+    finally:
+        print("Server stopped")
+
+        horde_app.qdrant_client.close()
+        await Tortoise.close_connections()
 
 if __name__ == "__main__":
-    try:
-        asyncio.run(main())
-    except KeyboardInterrupt:
-        # Clean shutdown for Tortoise connections
-        asyncio.run(Tortoise.close_connections())
+    asyncio.run(main())