Fix ApplyTextEdits replacement index calculation and port probe handshake

UnityMcpBridge/Editor/Tools/ManageScript.cs

@@ -557,13 +557,20 @@ private static object ApplyTextEdits(
                             // If the edit overlaps the method span significantly, treat as replace_method
                             if (sp.start <= mStart + 2 && sp.end >= mStart + 1)
                             {
+                                var methodOriginal = original.Substring(mStart, mLen);
+                                int relStart = Math.Max(0, Math.Min(sp.start - mStart, methodOriginal.Length));
+                                int relEnd = Math.Max(relStart, Math.Min(sp.end - mStart, methodOriginal.Length));
+                                string replacementSnippet = methodOriginal
+                                    .Remove(relStart, relEnd - relStart)
+                                    .Insert(relStart, sp.text ?? string.Empty);
+
                                 var structEdits = new JArray();
                                 var op = new JObject
                                 {
                                     ["mode"] = "replace_method",
                                     ["className"] = name,
                                     ["methodName"] = methodName,
-                                    ["replacement"] = original.Remove(sp.start, sp.end - sp.start).Insert(sp.start, sp.text ?? string.Empty).Substring(mStart, (sp.text ?? string.Empty).Length + (sp.start - mStart) + (mLen - (sp.end - mStart)))
+                                    ["replacement"] = replacementSnippet
                                 };
                                 structEdits.Add(op);
                                 // Reuse structured path

UnityMcpBridge/UnityMcpServer~/src/port_discovery.py

@@ -18,6 +18,7 @@
 from typing import Optional, List
 import glob
 import socket
+import struct
 
 logger = logging.getLogger("unity-mcp-server")
 
@@ -56,14 +57,36 @@ def list_candidate_files() -> List[Path]:
     @staticmethod
     def _try_probe_unity_mcp(port: int) -> bool:
         """Quickly check if a Unity MCP listener is on this port.
-        Tries a short TCP connect, sends 'ping', expects a JSON 'pong'.
+        Performs a short TCP connect and ping/pong exchange. If the
+        server advertises ``FRAMING=1`` in its greeting, the ping and
+        pong are sent/received with an 8-byte big-endian length prefix.
         """
+
+        def _read_exact(sock: socket.socket, count: int) -> bytes:
+            buf = bytearray()
+            while len(buf) < count:
+                chunk = sock.recv(count - len(buf))
+                if not chunk:
+                    raise ConnectionError("Connection closed before reading expected bytes")
+                buf.extend(chunk)
+            return bytes(buf)
+
         try:
             with socket.create_connection(("127.0.0.1", port), PortDiscovery.CONNECT_TIMEOUT) as s:
                 s.settimeout(PortDiscovery.CONNECT_TIMEOUT)
                 try:
-                    s.sendall(b"ping")
-                    data = s.recv(512)
+                    greeting = s.recv(256)
+                    text = greeting.decode('ascii', errors='ignore') if greeting else ''
+                    payload = b"ping"
+                    if 'FRAMING=1' in text:
+                        header = struct.pack('>Q', len(payload))
+                        s.sendall(header + payload)
+                        resp_header = _read_exact(s, 8)
+                        resp_len = struct.unpack('>Q', resp_header)[0]
+                        data = _read_exact(s, resp_len)
+                    else:
+                        s.sendall(payload)
+                        data = s.recv(512)
                     # Minimal validation: look for a success pong response
                     if data and b'"message":"pong"' in data:
                         return True