Merge pull request #324 from virgil-at-biocompute/fix/mcp-protocol-version-negotiation

fix: negotiate MCP protocol version instead of hardcoding

mempalace/mcp_server.py

@@ -837,17 +837,31 @@ 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__},
             },

tests/test_mcp_server.py

@@ -42,6 +42,50 @@ class TestHandleRequest:
         assert resp["result"]["serverInfo"]["name"] == "mempalace"
         assert resp["id"] == 1
 
+    def test_initialize_negotiates_client_version(self):
+        from mempalace.mcp_server import handle_request
+
+        resp = handle_request(
+            {
+                "method": "initialize",
+                "id": 1,
+                "params": {"protocolVersion": "2025-11-25"},
+            }
+        )
+        assert resp["result"]["protocolVersion"] == "2025-11-25"
+
+    def test_initialize_negotiates_older_supported_version(self):
+        from mempalace.mcp_server import handle_request
+
+        resp = handle_request(
+            {
+                "method": "initialize",
+                "id": 1,
+                "params": {"protocolVersion": "2025-03-26"},
+            }
+        )
+        assert resp["result"]["protocolVersion"] == "2025-03-26"
+
+    def test_initialize_unknown_version_falls_back_to_latest(self):
+        from mempalace.mcp_server import handle_request
+
+        resp = handle_request(
+            {
+                "method": "initialize",
+                "id": 1,
+                "params": {"protocolVersion": "9999-12-31"},
+            }
+        )
+        from mempalace.mcp_server import SUPPORTED_PROTOCOL_VERSIONS
+
+        assert resp["result"]["protocolVersion"] == SUPPORTED_PROTOCOL_VERSIONS[0]
+
+    def test_initialize_missing_version_uses_oldest(self):
+        from mempalace.mcp_server import handle_request, SUPPORTED_PROTOCOL_VERSIONS
+
+        resp = handle_request({"method": "initialize", "id": 1, "params": {}})
+        assert resp["result"]["protocolVersion"] == SUPPORTED_PROTOCOL_VERSIONS[-1]
+
     def test_notifications_initialized_returns_none(self):
         from mempalace.mcp_server import handle_request