CompileClient.cs

using System;
using System.Net;
using UnityEditor;
using System.Net.Sockets;
using System.Threading.Tasks;


[InitializeOnLoad]
public class CompileClient
{
    public static bool setRefresh;
    static TcpListener server = null;  // this is the http server

    static CompileClient()
    {
        Task.Run(startServer);

        EditorApplication.update += onUpdate;
    }

    private static void onUpdate()
    {
        if (!setRefresh) return;
        if (EditorApplication.isCompiling) return;
        if (EditorApplication.isUpdating) return;

        AssetDatabase.Refresh();
        setRefresh = false;
    }

    private static void startServer()
    {
        server = new TcpListener(IPAddress.Parse("127.0.0.1"), 3001);
        server.Start();

        Byte[] bytes = new Byte[256];
        while (true)
        {
            TcpClient client = server.AcceptTcpClient();
            NetworkStream stream = client.GetStream();

            int i;
            while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
            {
                setRefresh = true;
            }
            client.Close();
        }
    }
}

watch.py

# pip install watchgod
# copy this file to project's root
# run python watch.py
from watchgod import watch, AllWatcher, DefaultDirWatcher
import socket
import sys
import time


class CsharpWatcher(DefaultDirWatcher):
    def should_watch_file(self, entry: 'DirEntry') -> bool:
        return entry.name.endswith(('.cs'))


def notify():
    try:
        time.sleep(0.2)
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.connect(('127.0.0.1', 3001))
        s.send(b"hi!")
    except:
        print("error! ", sys.exc_info()[0])

for changes in watch('./Assets/', watcher_cls=CsharpWatcher):
    notify()
    pass