I think this is way less hacky

src/containers/container_manager_client.py

@@ -288,7 +288,11 @@ def _send_select(self) -> None:
         try:
             while not self.recv_closed:
                 if select.select([sys.stdin], [], [], 0) == ([sys.stdin], [], []):
-                    self.sock.send(bytes(sys.stdin.readline(), "utf-8"))
+                    buffer = bytes(sys.stdin.readline(), "utf-8")
+                    while buffer:
+                        msg = buffer[:255]
+                        self.sock.send(bytes([len(msg)]) + msg)
+                        buffer = buffer[255:]
                 else:
                     self.sock.send(b"\x00")
                 time.sleep(0.1)
@@ -309,7 +313,11 @@ def _send_msvcrt(self) -> None:
 
                     if char == "\r":
                         print(end="\n")
-                        self.sock.send(bytes(msg + "\n", "utf-8"))
+                        buffer = bytes(msg + "\n", "utf-8")
+                        while buffer:
+                            msg = buffer[:255]
+                            self.sock.send(bytes([len(msg)]) + msg)
+                            buffer = buffer[255:]
                         msg = ""
 
                     elif char == "\b":

src/containers/container_manager_server.py

@@ -397,8 +397,11 @@ def send_and_recv(self):
 
     def _recv(self):
         try:
-            while msg := self.client_sock.recv(1024):
-                self.stdin.write(bytes(filter(lambda b: b, msg)))
+            while msg := self.client_sock.recv(1 << 16):
+                while msg:
+                    size = msg[0]
+                    self.stdin.write(msg[1:size + 1])
+                    msg = msg[size + 1:]
         except (ConnectionError, OSError):
             pass