fix: negotiate MCP protocol version instead of hardcoding

The initialize handler hardcoded protocolVersion "2024-11-05", which
causes newer MCP clients (e.g. Claude Code) to reject the connection
when they negotiate "2025-11-25" or later.

Echo the client's requested version if it is in the supported set,
otherwise fall back to the latest supported version. This keeps
backwards compatibility with older clients while allowing newer ones
to connect.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

mempalace/mcp_server.py

@@ -717,17 +717,31 @@ TOOLS = {
 }
 
 
+SUPPORTED_PROTOCOL_VERSIONS = [
+    "2025-11-25",
+    "2025-06-18",
+    "2025-03-26",
+    "2024-11-05",
+]
+
+
 def handle_request(request):
     method = request.get("method", "")
     params = request.get("params", {})
     req_id = request.get("id")
 
     if method == "initialize":
+        client_version = params.get("protocolVersion", SUPPORTED_PROTOCOL_VERSIONS[-1])
+        negotiated = (
+            client_version
+            if client_version in SUPPORTED_PROTOCOL_VERSIONS
+            else SUPPORTED_PROTOCOL_VERSIONS[0]
+        )
         return {
             "jsonrpc": "2.0",
             "id": req_id,
             "result": {
-                "protocolVersion": "2024-11-05",
+                "protocolVersion": negotiated,
                 "capabilities": {"tools": {}},
                 "serverInfo": {"name": "mempalace", "version": __version__},
             },