diff --git a/osprey_ui/src/components/event_stream/EventStream.tsx b/osprey_ui/src/components/event_stream/EventStream.tsx
index 33eae01..c2575f1 100644
--- a/osprey_ui/src/components/event_stream/EventStream.tsx
+++ b/osprey_ui/src/components/event_stream/EventStream.tsx
@@ -7,7 +7,6 @@ import {
 } from '@ant-design/icons';
 import { Empty, List, Skeleton, Tooltip, Spin } from 'antd';
 import classNames from 'classnames';
-import { memoize } from 'lodash';
 import { AutoSizer, List as VList, ListRowProps } from 'react-virtualized';
 import shallow from 'zustand/shallow';
 
@@ -20,6 +19,7 @@ import EventStreamIcon from '../../uikit/icons/EventStreamIcon';
 import Panel from '../common/Panel';
 import EventStreamCard from './EventStreamCard';
 import FeatureSelectModal from './FeatureSelectModal';
+import { getSummaryFeaturesForEvent } from './getSummaryFeaturesForEvent';
 
 import styles from './EventStream.module.css';
 import { FeatureLocation } from '../../types/ConfigTypes';
@@ -119,14 +119,6 @@ const EventStream: React.FC = () => {
     return eventStream.length - index < 5;
   };
 
-  const getSummaryFeatures = React.useMemo(
-    () =>
-      memoize((actionName: string) =>
-        defaultSummaryFeatures.filter((f) => f.appliesTo(actionName)).map((f) => f.features)
-      ),
-    [defaultSummaryFeatures]
-  );
-
   const renderListRows = ({ key, index, style, isVisible }: ListRowProps) => {
     if (isVisible && shouldLoadMoreResults(index)) {
       handlePaginatedScanQuery();
@@ -134,7 +126,9 @@ const EventStream: React.FC = () => {
 
     const item = eventStream[index];
     const features =
-      customSummaryFeatures == null ? getSummaryFeatures(item.extracted_features.ActionName) : [customSummaryFeatures];
+      customSummaryFeatures == null
+        ? getSummaryFeaturesForEvent(item, defaultSummaryFeatures)
+        : [customSummaryFeatures];
 
     return (
       <List.Item
@@ -159,7 +153,7 @@ const EventStream: React.FC = () => {
 
     const features =
       customSummaryFeatures == null
-        ? getSummaryFeatures(eventStream[index].extracted_features.ActionName)
+        ? getSummaryFeaturesForEvent(eventStream[index], defaultSummaryFeatures)
         : [customSummaryFeatures];
 
     if (!features.length) {
diff --git a/osprey_ui/src/components/event_stream/getSummaryFeaturesForEvent.test.ts b/osprey_ui/src/components/event_stream/getSummaryFeaturesForEvent.test.ts
new file mode 100644
index 0000000..76f2933
--- /dev/null
+++ b/osprey_ui/src/components/event_stream/getSummaryFeaturesForEvent.test.ts
@@ -0,0 +1,76 @@
+import { describe, it, expect } from '@rstest/core';
+
+import DefaultFeature from '../../models/DefaultFeature';
+import { OspreyEvent } from '../../types/QueryTypes';
+
+import { getSummaryFeaturesForEvent } from './getSummaryFeaturesForEvent';
+
+const makeEvent = (extracted: Record<string, string>): OspreyEvent => {
+  return {
+    timestamp: '2025-01-01T00:00:00Z',
+    id: 'evt-1',
+    extracted_features: extracted,
+  };
+};
+
+describe('getSummaryFeaturesForEvent', () => {
+  it('returns configured defaults when an action-name pattern matches', () => {
+    const defaults = [
+      new DefaultFeature(['LoginAction'], ['UserId', 'IpAddress']),
+      new DefaultFeature(['NotApplicable'], ['ShouldNotAppear']),
+    ];
+    const event = makeEvent({ ActionName: 'LoginAction', UserId: '123', IpAddress: '10.0.0.1' });
+
+    const result = getSummaryFeaturesForEvent(event, defaults);
+
+    expect(result).toEqual([['UserId', 'IpAddress']]);
+  });
+
+  it('returns all matching default blocks when multiple apply', () => {
+    const defaults = [
+      new DefaultFeature(['*'], ['UserId']),
+      new DefaultFeature(['SendMessage'], ['ChannelId', 'GuildId']),
+    ];
+    const event = makeEvent({ ActionName: 'SendMessage', UserId: '1', ChannelId: 'c', GuildId: 'g' });
+
+    const result = getSummaryFeaturesForEvent(event, defaults);
+
+    expect(result).toEqual([['UserId'], ['ChannelId', 'GuildId']]);
+  });
+
+  it('falls back to every extracted feature key (excluding ActionName) when no defaults are configured', () => {
+    const event = makeEvent({ ActionName: 'AnythingAction', UserId: '42', ChannelId: 'c1', GuildId: 'g1' });
+
+    const result = getSummaryFeaturesForEvent(event, []);
+
+    expect(result).toHaveLength(1);
+    expect(new Set(result[0])).toEqual(new Set(['UserId', 'ChannelId', 'GuildId']));
+    expect(result[0]).not.toContain('ActionName');
+  });
+
+  it('falls back to event keys when defaults exist but none match the action', () => {
+    const defaults = [new DefaultFeature(['SomeOtherAction'], ['IrrelevantField'])];
+    const event = makeEvent({ ActionName: 'UnmatchedAction', UserId: 'u', GuildId: 'g' });
+
+    const result = getSummaryFeaturesForEvent(event, defaults);
+
+    expect(result).toHaveLength(1);
+    expect(new Set(result[0])).toEqual(new Set(['UserId', 'GuildId']));
+  });
+
+  it('returns an empty list when the event has only ActionName and no defaults apply', () => {
+    const event = makeEvent({ ActionName: 'NakedAction' });
+
+    const result = getSummaryFeaturesForEvent(event, []);
+
+    expect(result).toEqual([]);
+  });
+
+  it('returns an empty list when the event has no extracted features at all', () => {
+    const event = makeEvent({});
+
+    const result = getSummaryFeaturesForEvent(event, []);
+
+    expect(result).toEqual([]);
+  });
+});
diff --git a/osprey_ui/src/components/event_stream/getSummaryFeaturesForEvent.ts b/osprey_ui/src/components/event_stream/getSummaryFeaturesForEvent.ts
new file mode 100644
index 0000000..1301a9e
--- /dev/null
+++ b/osprey_ui/src/components/event_stream/getSummaryFeaturesForEvent.ts
@@ -0,0 +1,36 @@
+import DefaultFeature from '../../models/DefaultFeature';
+import { OspreyEvent } from '../../types/QueryTypes';
+
+/**
+ * Resolves which feature blocks to render in an EventStreamCard when the
+ * user has not chosen a custom selection.
+ *
+ * Order of precedence:
+ *   1. Any DefaultFeature whose action-name pattern matches the event's
+ *      ActionName.
+ *   2. Otherwise, a single block containing every key on the event
+ *      except ActionName (already rendered as the card title).
+ */
+export const getSummaryFeaturesForEvent = (
+  event: OspreyEvent,
+  defaultSummaryFeatures: DefaultFeature[]
+): Array<readonly string[]> => {
+  const actionName = event.extracted_features.ActionName;
+  const matched = defaultSummaryFeatures.filter((f) => {
+    return f.appliesTo(actionName);
+  });
+
+  if (matched.length > 0) {
+    return matched.map((f) => {
+      return f.features;
+    });
+  }
+
+  const fallback = Object.keys(event.extracted_features).filter((key) => {
+    return key !== 'ActionName';
+  });
+
+  if (fallback.length === 0) return [];
+
+  return [fallback];
+};