diff --git a/events/serializers.py b/events/serializers.py
index 66f2e44..9b7ee45 100644
--- a/events/serializers.py
+++ b/events/serializers.py
@@ -23,9 +23,12 @@ class EventListSerializer(serializers.ModelSerializer):
 
 class EventDetailSerializer(serializers.ModelSerializer):
     """Detail view: includes full `data` payload."""
+    # NOTE as with Issue.grouping_keys: check viewset for prefetching
+    # grouping_key = serializers.CharField(source="grouping.grouping_key", read_only=True)
 
     class Meta:
         model = Event
         fields = EventListSerializer.Meta.fields + [
             "data",
+            # "grouping_key"  # TODO (likely) once we have the "expand" idea implemented
         ]
diff --git a/issues/serializers.py b/issues/serializers.py
index 898e315..6cbc200 100644
--- a/issues/serializers.py
+++ b/issues/serializers.py
@@ -4,6 +4,8 @@ from .models import Issue
 
 
 class IssueSerializer(serializers.ModelSerializer):
+    # grouping_keys = serializers.SerializerMethodField()  # read-only list of strings
+
     class Meta:
         model = Issue
 
@@ -32,4 +34,9 @@ class IssueSerializer(serializers.ModelSerializer):
             # "events_at",  too "raw"? i.e. too implementation-tied?
             "is_muted",
             # "unmute_on_volume_based_conditions",  too "raw"? i.e. too implementation-tied?
+            # "grouping_keys",  TODO (likely) once we have the "expand" idea implemented
         ]
+
+    # def get_grouping_keys(self, obj):
+    #     # TODO: prefetch grouping_key in IssueViewSet
+    #     return list(obj.grouping_set.values_list("grouping_key", flat=True))