feat(rest-api): return valid JSON from DELETE endpoints

rest-api/api/pkg/api/handler/allocation.go

@@ -1504,5 +1504,5 @@ func (dah DeleteAllocationHandler) Handle(c echo.Context) error {
 
 	// Create response
 	logger.Info().Msg("finishing API handler")
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/handler/deletion_response_test_helper_test.go

@@ -0,0 +1,22 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package handler
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/NVIDIA/infra-controller/rest-api/api/pkg/api/model"
+)
+
+func assertDeletionAcceptedResponse(t *testing.T, body []byte) {
+	t.Helper()
+
+	var resp model.APIDeletionAcceptedResponse
+	require.NoError(t, json.Unmarshal(body, &resp))
+	assert.Equal(t, model.DeletionRequestAcceptedMessage, resp.Message)
+}

rest-api/api/pkg/api/handler/infinibandpartition.go

@@ -1129,6 +1129,6 @@ func (dibph DeleteInfiniBandPartitionHandler) Handle(c echo.Context) error {
 
 	// Create response
 	logger.Info().Msg("finishing API handler")
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 
 }

rest-api/api/pkg/api/handler/instance.go

@@ -4954,7 +4954,7 @@ func (dih DeleteInstanceHandler) Handle(c echo.Context) error {
 	// Return response
 	logger.Info().Msg("finishing API handler")
 
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }
 
 // GetInstanceStatusDetailsHandler is the API Handler for getting Instance StatusDetail records

rest-api/api/pkg/api/handler/instance_test.go

@@ -9707,7 +9707,7 @@ func TestDeleteInstanceHandler_Handle(t *testing.T) {
 			if tt.args.respCode != http.StatusAccepted {
 				return
 			}
-			assert.Contains(t, rec.Body.String(), "Deletion request was accepted")
+			assertDeletionAcceptedResponse(t, rec.Body.Bytes())
 
 			// Verify Instance in terminating state
 			insDAO := cdbm.NewInstanceDAO(dbSession)

rest-api/api/pkg/api/handler/instancetype.go

@@ -1551,5 +1551,5 @@ func (dith DeleteInstanceTypeHandler) Handle(c echo.Context) error {
 	// Create response
 	logger.Info().Msg("finishing API handler")
 
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/handler/ipblock.go

@@ -1167,5 +1167,5 @@ func (dipbh DeleteIPBlockHandler) Handle(c echo.Context) error {
 	// Create response
 	logger.Info().Msg("finishing API handler")
 
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/handler/machine.go

@@ -1957,5 +1957,5 @@ func (umh DeleteMachineHandler) Handle(c echo.Context) error {
 
 	logger.Info().Msg("finishing API handler")
 
-	return c.JSON(http.StatusAccepted, nil)
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/handler/machineinstancetype.go

@@ -752,5 +752,5 @@ func (dmith DeleteMachineInstanceTypeHandler) Handle(c echo.Context) error {
 	// Return response
 	logger.Info().Msg("finishing API handler")
 
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/handler/machinevalidation.go

@@ -1671,5 +1671,5 @@ func (handler DeleteMachineValidationExternalConfigHandler) Handle(c echo.Contex
 
 	// Create response
 	logger.Info().Msg("finishing API handler")
-	return c.JSON(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/handler/networksecuritygroup.go

@@ -982,7 +982,7 @@ func (dnsgh DeleteNetworkSecurityGroupHandler) Handle(c echo.Context) error {
 	// Return response
 	logger.Info().Msg("finishing API handler")
 
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }
 
 // ~~~~~ Delete Handler ~~~~~ //

rest-api/api/pkg/api/handler/nvlinklogicalpartition.go

@@ -1352,5 +1352,5 @@ func (dibph DeleteNVLinkLogicalPartitionHandler) Handle(c echo.Context) error {
 
 	// Create response
 	logger.Info().Msg("finishing API handler")
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/handler/operatingsystem.go

@@ -1605,6 +1605,6 @@ func (dsh DeleteOperatingSystemHandler) Handle(c echo.Context) error {
 
 	// Create response
 	logger.Info().Msg("finishing API handler")
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 
 }

rest-api/api/pkg/api/handler/site.go

@@ -1144,7 +1144,7 @@ func (dsh DeleteSiteHandler) Handle(c echo.Context) error {
 	// Create response
 	logger.Info().Msg("finishing API handler")
 
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }
 
 // GetSiteStatusDetailsHandler is the API Handler for getting Site StatusDetail records

rest-api/api/pkg/api/handler/sshkey.go

@@ -1008,5 +1008,5 @@ func (dskh DeleteSSHKeyHandler) Handle(c echo.Context) error {
 	// Return response
 	logger.Info().Msg("finishing API handler")
 
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/handler/sshkeygroup.go

@@ -1659,5 +1659,5 @@ func (dskgh DeleteSSHKeyGroupHandler) Handle(c echo.Context) error {
 	// Return response
 	logger.Info().Msg("finishing API handler")
 
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/handler/subnet.go

@@ -1164,5 +1164,5 @@ func (dsh DeleteSubnetHandler) Handle(c echo.Context) error {
 
 	// Create response
 	logger.Info().Msg("finishing API handler")
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/handler/tenantaccount.go

@@ -866,5 +866,5 @@ func (dtah DeleteTenantAccountHandler) Handle(c echo.Context) error {
 	// Create response
 	logger.Info().Msg("finishing API handler")
 
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/handler/vpc.go

@@ -1818,5 +1818,5 @@ func (dvh DeleteVPCHandler) Handle(c echo.Context) error {
 	// Return response
 	logger.Info().Msg("finishing API handler")
 
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/handler/vpc_test.go

@@ -3465,7 +3465,7 @@ func TestDeleteVPCHandler_Handle(t *testing.T) {
 			if tt.args.respCode != http.StatusAccepted {
 				return
 			}
-			assert.Contains(t, rec.Body.String(), "Deletion request was accepted")
+			assertDeletionAcceptedResponse(t, rec.Body.Bytes())
 
 			// Verify VPC in deleting state
 			vpcDAO := cdbm.NewVpcDAO(dbSession)

rest-api/api/pkg/api/handler/vpcprefix.go

@@ -1160,5 +1160,5 @@ func (dsh DeleteVpcPrefixHandler) Handle(c echo.Context) error {
 
 	// Create response
 	logger.Info().Msg("finishing API handler")
-	return c.String(http.StatusAccepted, "Deletion request was accepted")
+	return c.JSON(http.StatusAccepted, model.NewAPIDeletionAcceptedResponse())
 }

rest-api/api/pkg/api/model/deletion.go

@@ -0,0 +1,22 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package model
+
+const (
+	// DeletionRequestAcceptedMessage is returned when an asynchronous delete has
+	// been accepted for processing.
+	DeletionRequestAcceptedMessage = "Deletion request was accepted"
+)
+
+// APIDeletionAcceptedResponse is the JSON body for accepted async DELETE requests.
+type APIDeletionAcceptedResponse struct {
+	Message string `json:"message"`
+}
+
+// NewAPIDeletionAcceptedResponse returns the JSON body for accepted async deletes.
+func NewAPIDeletionAcceptedResponse() APIDeletionAcceptedResponse {
+	return APIDeletionAcceptedResponse{
+		Message: DeletionRequestAcceptedMessage,
+	}
+}

rest-api/api/pkg/api/model/deletion_test.go

@@ -0,0 +1,24 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package model
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestAPIDeletionAcceptedResponse_JSON(t *testing.T) {
+	t.Parallel()
+
+	payload, err := json.Marshal(NewAPIDeletionAcceptedResponse())
+	require.NoError(t, err)
+	assert.JSONEq(t, `{"message":"`+DeletionRequestAcceptedMessage+`"}`, string(payload))
+
+	var decoded APIDeletionAcceptedResponse
+	require.NoError(t, json.Unmarshal(payload, &decoded))
+	assert.Equal(t, DeletionRequestAcceptedMessage, decoded.Message)
+}