fix(kvtpl): Unable to fully restore a fresh backup

internal/storage/kvtpl/provider.go

@@ -120,9 +120,11 @@ func (s *KVStorage) CreateProvider(prvd *happydns.Provider) error {
 
 func (s *KVStorage) UpdateProvider(prvd *happydns.Provider) error {
 	// Load the existing record so we can detect an owner change and clean up
-	// the stale index entry.
+	// the stale index entry. UpdateProvider is also used by the backup restore
+	// path where the primary may not exist yet, so a missing old record is not
+	// an error.
 	old, err := s.GetProvider(prvd.Id)
-	if err != nil {
+	if err != nil && !errors.Is(err, happydns.ErrProviderNotFound) {
 		return err
 	}
 
@@ -130,7 +132,7 @@ func (s *KVStorage) UpdateProvider(prvd *happydns.Provider) error {
 		return err
 	}
 
-	if !old.Owner.Equals(prvd.Owner) {
+	if old != nil && !old.Owner.Equals(prvd.Owner) {
 		if err := s.db.Delete(providerOwnerKey(old.Owner, prvd.Id)); err != nil {
 			log.Printf("UpdateProvider: failed to delete stale owner index for owner %s: %v", old.Owner.String(), err)
 		}

internal/storage/kvtpl/provider_restore_test.go

@@ -0,0 +1,75 @@
+// This file is part of the happyDomain (R) project.
+// Copyright (c) 2020-2026 happyDomain
+// Authors: Pierre-Olivier Mercier, et al.
+//
+// This program is offered under a commercial and under the AGPL license.
+// For commercial licensing, contact us at <contact@happydomain.org>.
+//
+// For AGPL licensing:
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package database_test
+
+import (
+	"testing"
+
+	happydns "git.happydns.org/happyDomain/model"
+)
+
+type stubProviderBody struct {
+	Field string `json:"field"`
+}
+
+func (stubProviderBody) InstantiateProvider() (happydns.ProviderActuator, error) {
+	return nil, nil
+}
+
+// TestUpdateProviderUpsertsIntoEmptyStore guards the backup restore path: a
+// backup is loaded into a fresh database through UpdateProvider, so the primary
+// record does not exist yet. A missing old record must not be treated as an
+// error (mirrors UpdateDomain/UpdateZone, which are already upserts).
+func TestUpdateProviderUpsertsIntoEmptyStore(t *testing.T) {
+	s := newStorage(t)
+
+	owner, _ := happydns.NewRandomIdentifier()
+	id, _ := happydns.NewRandomIdentifier()
+	prvd := &happydns.Provider{
+		ProviderMeta: happydns.ProviderMeta{Type: "stub", Id: id, Owner: owner},
+		Provider:     stubProviderBody{Field: "value"},
+	}
+
+	if err := s.UpdateProvider(prvd); err != nil {
+		t.Fatalf("UpdateProvider into empty store returned error: %v", err)
+	}
+
+	got, err := s.GetProvider(id)
+	if err != nil {
+		t.Fatalf("GetProvider after upsert: %v", err)
+	}
+	if !got.Id.Equals(id) {
+		t.Errorf("restored provider id = %s, want %s", got.Id.String(), id.String())
+	}
+	if !got.Owner.Equals(owner) {
+		t.Errorf("restored provider owner = %s, want %s", got.Owner.String(), owner.String())
+	}
+
+	// The owner index must also be populated so the provider is listable.
+	providers, err := s.ListProviders(&happydns.User{Id: owner})
+	if err != nil {
+		t.Fatalf("ListProviders: %v", err)
+	}
+	if len(providers) != 1 {
+		t.Fatalf("ListProviders returned %d providers, want 1", len(providers))
+	}
+}