fix(timeseries): Improve parsing of null groups

static/app/utils/timeSeries/parseGroupBy.spec.tsx

@@ -6,6 +6,11 @@ describe('parseGroupBy', () => {
     expect(result).toBeNull();
   });
 
+  it('returns null for "None" group name', () => {
+    const result = parseGroupBy('None', ['field1']);
+    expect(result).toEqual([{key: 'field1', value: null}]);
+  });
+
   it('parses single field and value correctly', () => {
     const result = parseGroupBy('value1', ['field1']);
     expect(result).toEqual([{key: 'field1', value: 'value1'}]);

static/app/utils/timeSeries/parseGroupBy.tsx

@@ -6,6 +6,7 @@ export function parseGroupBy(
   groupName: string,
   fields: string[]
 ): TimeSeriesGroupBy[] | null {
+  // "Other", by definition, does not have any known group by values
   if (groupName === 'Other') {
     return null;
   }
@@ -15,6 +16,15 @@ export function parseGroupBy(
   }
 
   const groupKeys = fields;
+
+  // `/events-stats/` converts Python's `None` into `"None"`. Here, we do the reverse
+  if (groupName === 'None') {
+    return groupKeys.map(groupKey => ({
+      key: groupKey,
+      value: null,
+    }));
+  }
+
   const groupValues = groupName.split(DELIMITER);
 
   // If the `groupName` contains commas, that will result in more values than

static/app/views/dashboards/widgets/timeSeriesWidget/formatters/formatTimeSeriesLabel.spec.tsx

@@ -91,7 +91,7 @@ describe('formatSeriesName', () => {
         'v0.0.2',
       ],
       ['p95(span.duration)', [{key: 'release', value: 'v0.0.2'}], 'v0.0.2'],
-      ['p95(span.duration)', [{key: 'gen_ai.request.model', value: null}], 'null'],
+      ['p95(span.duration)', [{key: 'gen_ai.request.model', value: null}], '(no value)'],
       [
         'p95(span.duration)',
         [

static/app/views/dashboards/widgets/timeSeriesWidget/formatters/formatTimeSeriesLabel.tsx

@@ -28,8 +28,10 @@ export function formatTimeSeriesLabel(timeSeries: TimeSeries): string {
           return formatVersion(groupBy.value);
         }
 
-        // String interpolation converts `null` to `"null"` and `undefined` to
-        // `"undefined"`, which is what we want, rather than an empty string
+        if (groupBy.value === null) {
+          return t('(no value)');
+        }
+
         return `${groupBy.value}`;
       })
       .join(',')}`;

static/app/views/insights/agents/components/modelName.tsx

@@ -2,6 +2,7 @@ import styled from '@emotion/styled';
 import {PlatformIcon} from 'platformicons';
 
 import {Flex} from 'sentry/components/core/layout';
+import {t} from 'sentry/locale';
 import type {Space} from 'sentry/utils/theme/theme';
 
 interface ModelNameProps {
@@ -19,7 +20,7 @@ export function ModelName({modelId, provider, size = 16, gap = 'md'}: ModelNameP
       <IconWrapper>
         <PlatformIcon platform={platform ?? 'unknown'} size={size} />
       </IconWrapper>
-      <NameWrapper>{modelId}</NameWrapper>
+      <NameWrapper>{modelId === 'null' ? t('(no value)') : modelId}</NameWrapper>
     </Flex>
   );
 }