fix(mcp): preserve edited settings in static connection previews

litellm/proxy/_experimental/mcp_server/rest_endpoints.py

@@ -1234,7 +1234,7 @@ if MCP_AVAILABLE:
         return client_id, client_secret, scopes
 
     _STAGED_AUTH_VALUE_AUTH_TYPES: Final = frozenset(
-        (MCPAuth.api_key, MCPAuth.bearer_token, MCPAuth.basic, MCPAuth.authorization)
+        (MCPAuth.api_key, MCPAuth.bearer_token, MCPAuth.basic, MCPAuth.authorization, MCPAuth.token)
     )
 
     @dataclass(frozen=True, slots=True)
@@ -1318,8 +1318,15 @@ if MCP_AVAILABLE:
             if _oauth2_flow == "client_credentials" and not request.token_url:
                 _oauth2_flow = None
 
+            # Static previews inherit credentials before this step, but must not resolve back to
+            # the saved record during client creation and discard the edited connection settings.
+            preview_server_id: Final = (
+                ""
+                if request.auth_type in _STAGED_AUTH_VALUE_AUTH_TYPES or request.auth_type in (None, MCPAuth.none)
+                else request.server_id or ""
+            )
             server_model: Final = MCPServer(
-                server_id=request.server_id or "",
+                server_id=preview_server_id,
                 name=request.alias or request.server_name or "",
                 url=request.url,
                 transport=request.transport,

tests/test_litellm/proxy/_experimental/mcp_server/test_rest_endpoints.py

@@ -87,6 +87,72 @@ def _route_has_dependency(route, dependency) -> bool:
 
 
 class TestExecuteWithMcpClient:
+    @pytest.mark.asyncio
+    @pytest.mark.parametrize(
+        ("auth_type", "auth_value", "expected_auth"),
+        (
+            (MCPAuth.none, None, {}),
+            (MCPAuth.basic, "preview:correct", {"Authorization": "Basic cHJldmlldzpjb3JyZWN0"}),
+            (MCPAuth.basic, None, {"Authorization": "Basic cHJldmlldzpzdG9yZWQ="}),
+            (MCPAuth.bearer_token, "edited", {"Authorization": "Bearer edited"}),
+            (MCPAuth.api_key, "edited", {"X-API-Key": "edited"}),
+            (MCPAuth.token, "edited", {"Authorization": "token edited"}),
+            (MCPAuth.authorization, "Custom edited", {"Authorization": "Custom edited"}),
+        ),
+    )
+    async def test_static_preview_uses_edited_connection_instead_of_registered_server(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+        auth_type: MCPAuth,
+        auth_value: str | None,
+        expected_auth: dict[str, str],
+    ) -> None:
+        from starlette.datastructures import Headers
+
+        from litellm.experimental_mcp_client.client import MCPClient
+        from litellm.proxy._experimental.mcp_server.mcp_server_manager import MCPServerManager
+        from litellm.proxy.management_endpoints import mcp_management_endpoints
+
+        saved: Final = MCPServer(
+            server_id="saved-preview-server",
+            name="saved",
+            url="https://stored.example/mcp",
+            transport=MCPTransport.http,
+            auth_type=MCPAuth.basic,
+            authentication_token="preview:stored",
+        )
+        manager: Final = MCPServerManager()
+        manager.registry = {saved.server_id: saved}
+        monkeypatch.setattr(rest_endpoints, "global_mcp_server_manager", manager)
+        monkeypatch.setattr(mcp_management_endpoints, "global_mcp_server_manager", manager)
+        payload: Final = NewMCPServerRequest(
+            server_id=saved.server_id,
+            server_name="edited",
+            url="https://edited.example/mcp",
+            transport=MCPTransport.sse,
+            auth_type=auth_type,
+            credentials={"auth_value": auth_value} if auth_value is not None else None,
+            static_headers={"X-Preview": "edited"},
+        )
+        staged: Final = rest_endpoints._stage_server_test(payload, Headers())
+
+        async def inspect_connection(client: MCPClient) -> dict[str, object]:
+            return {"url": client.server_url, "transport": client.transport_type, "headers": client._get_auth_headers()}
+
+        result: Final = await rest_endpoints._execute_with_mcp_client(
+            staged.request,
+            inspect_connection,
+            mcp_auth_header=staged.mcp_auth_header,
+            oauth2_headers=staged.oauth2_headers,
+        )
+        assert result == {
+            "url": "https://edited.example/mcp",
+            "transport": MCPTransport.sse,
+            "headers": {"X-Preview": "edited", **expected_auth},
+        }
+        assert manager.get_mcp_server_by_id(saved.server_id) is saved
+        assert saved.url == "https://stored.example/mcp"
+
     @pytest.mark.asyncio
     async def test_redacts_stack_trace(self, monkeypatch):
         async def fake_create_client(*args, **kwargs):