fix(sdk): tolerate additive response fields

rest-api/openapi/templates/go/model_simple.mustache

@@ -548,7 +548,6 @@ func (o *{{{classname}}}) UnmarshalJSON(data []byte) (err error) {
 	var{{{classname}}} := _{{{classname}}}{}
 
 	decoder := json.NewDecoder(bytes.NewReader(data))
-	decoder.DisallowUnknownFields()
 	err = decoder.Decode(&var{{{classname}}})
 
 	if err != nil {
@@ -570,4 +569,3 @@ func (o *{{{classname}}}) UnmarshalJSON(data []byte) (err error) {
 {{/isArray}}
 {{/vendorExtensions.x-go-generate-unmarshal-json}}
 {{>nullable_model}}
-

rest-api/sdk/standard/dpu_machine_test.go

@@ -0,0 +1,58 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package standard
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestDpuMachineUnmarshalJSON(t *testing.T) {
+	// "observed_at" is an additive server field absent from OpenAPI.
+	const response = `{
+		"id": "dpu-1",
+		"infrastructureProviderId": "provider-1",
+		"siteId": "site-1",
+		"hostMachineId": "host-1",
+		"dmiData": {"productSerial": "dpu-serial-1"},
+		"health": {
+			"observedAt": "2026-01-01T00:00:00Z",
+			"observed_at": "2026-01-01T00:00:00Z"
+		},
+		"state": "Ready",
+		"dpuNetworkConfig": {
+			"asn": 64512,
+			"vniDevice": "dpu-vni",
+			"managedHostConfigVersion": "v1",
+			"useAdminNetwork": true,
+			"remoteId": "remote-1",
+			"vpcIsolationBehavior": "Strict",
+			"statefulAclsEnabled": true,
+			"enableDhcp": true,
+			"isPrimaryDpu": true,
+			"datacenterAsn": 64513
+		}
+	}`
+
+	t.Run("allows additive fields", func(t *testing.T) {
+		var machine DpuMachine
+		require.NoError(t, json.Unmarshal([]byte(response), &machine))
+		require.Equal(t, "dpu-1", machine.Id)
+		require.Equal(t, "dpu-serial-1", machine.DmiData.GetProductSerial())
+		require.Equal(t, "2026-01-01T00:00:00Z", machine.Health.GetObservedAt())
+		require.Equal(t, "Ready", machine.State)
+		require.Equal(t, int32(64512), machine.DpuNetworkConfig.Asn)
+		require.Equal(t, "dpu-vni", machine.DpuNetworkConfig.VniDevice)
+	})
+
+	t.Run("requires schema fields", func(t *testing.T) {
+		withoutState := strings.Replace(response, "\t\t\"state\": \"Ready\",\n", "", 1)
+
+		var machine DpuMachine
+		require.Error(t, json.Unmarshal([]byte(withoutState), &machine))
+	})
+}