fix(runtime): make plugin and box connectors resilient

src/langbot/pkg/core/boot.py

@@ -46,21 +46,38 @@ async def make_app(loop: asyncio.AbstractEventLoop) -> app.Application:
 
 async def main(loop: asyncio.AbstractEventLoop):
     app_inst: app.Application | None = None
+    runtime_loop = asyncio.get_running_loop()
+    shutdown_requested = asyncio.Event()
+    run_task: asyncio.Task | None = None
     try:
-        # Hang system signal processing
         import signal
 
         def signal_handler(sig, frame):
-            if app_inst is not None:
-                app_inst.dispose()
             print('[Signal] Program exit.')
-            os._exit(0)
+            runtime_loop.call_soon_threadsafe(shutdown_requested.set)
 
         signal.signal(signal.SIGINT, signal_handler)
+        if hasattr(signal, 'SIGTERM'):
+            signal.signal(signal.SIGTERM, signal_handler)
 
         app_inst = await make_app(loop)
-        await app_inst.run()
+        if app_inst is None:
+            return
+        run_task = asyncio.create_task(app_inst.run())
+        shutdown_task = asyncio.create_task(shutdown_requested.wait())
+        done, pending = await asyncio.wait((run_task, shutdown_task), return_when=asyncio.FIRST_COMPLETED)
+        if shutdown_task in done:
+            await app_inst.shutdown()
+            if not run_task.done():
+                run_task.cancel()
+        for task in pending:
+            task.cancel()
+        results = await asyncio.gather(run_task, shutdown_task, return_exceptions=True)
+        run_result = results[0]
+        if isinstance(run_result, BaseException) and not isinstance(run_result, asyncio.CancelledError):
+            raise run_result
     except Exception:
-        if app_inst is not None:
-            app_inst.dispose()
         traceback.print_exc()
+    finally:
+        if app_inst is not None:
+            await app_inst.shutdown()