feat: [CODE-5485]: add ListScoped to usergroup controller (#5244)

* 2bc2ab fix: [CODE-5485]: use generic error message for missing spacePath

* 03bc0b fix: CODE-5485: move Harness-specific depth guard out of ListScoped

* 145ba1 fix: CODE-5485: reject repo paths in ListScoped; require depth <= 3

* 5470a7 feat: CODE-5485: add ListScoped to usergroup controller

app/api/controller/usergroup/list_scoped.go

@@ -0,0 +1,52 @@
+// Copyright 2023 Harness, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package usergroup
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	"github.com/harness/gitness/app/api/usererror"
+	"github.com/harness/gitness/app/auth"
+	"github.com/harness/gitness/types"
+	"github.com/harness/gitness/types/enum"
+)
+
+// ListScoped returns usergroups visible at a specific space path.
+// Unlike List, this is always active — no feature flag required.
+func (c Controller) ListScoped(
+	ctx context.Context,
+	session *auth.Session,
+	filter *types.ListQueryFilter,
+	spacePath string,
+) ([]*types.UserGroupInfo, error) {
+	if spacePath == "" {
+		return nil, usererror.Newf(http.StatusBadRequest, "spacePath is required")
+	}
+
+	space, err := getSpaceCheckAuth(
+		ctx, c.spaceFinder, c.authorizer, session, spacePath, enum.PermissionSpaceView,
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to acquire access to space: %w", err)
+	}
+
+	userGroupInfos, err := c.userGroupService.List(ctx, filter, space)
+	if err != nil {
+		return nil, fmt.Errorf("failed to list user groups: %w", err)
+	}
+	return userGroupInfos, nil
+}