fix(mixed-timeseries): derive per-series metric from label map to stop duplicating first metric (#37921)

When Query A (or B) on a Mixed Chart has multiple metrics plus at least
one Group By dimension, the display-name builder in transformProps.ts
always prepended metrics[0]'s label: the entryName.includes(metricPart)
guard is false for every series belonging to metrics[1+], so those
series were renamed to e.g. 'score_one, score_two, A' instead of
'score_two, A' — the 'first metric duplicated in legend/tooltip'
symptom reported in #37921 (residual follow-up to #37055).

Derive each series' metric from its label_map tuple
([metric, ...dimensions]) instead, matching what the per-series
formatter lookup already does. Single-element tuples (no metric part)
fall back to the first metric, preserving existing behavior for
single-metric charts and showQueryIdentifiers naming. Applied to both
the Query A and Query B paths.

Includes the regression test originally landed red on this branch,
verified red on master without the fix and green with it.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

superset-frontend/plugins/plugin-chart-echarts/src/MixedTimeseries/transformProps.ts

@@ -457,13 +457,23 @@ export default function transformProps(
     const seriesName = inverted[entryName] || entryName;
     const colorScaleKey = getOriginalSeries(seriesName, array);
 
+    const labelMapValues = rawLabelMap?.[seriesName];
+
     let displayName: string;
 
     if (groupby.length > 0) {
-      // When we have groupby, format as "metric, dimension"
+      // When we have groupby, format as "metric, dimension". Each series
+      // belongs to the metric recorded in its label-map tuple
+      // ([metric, ...dimensions]) — always using the first metric would
+      // prepend it to every other metric's series (#37921). Tuples without
+      // a metric part fall back to the first metric as before.
+      const metricDisplayName =
+        labelMapValues && labelMapValues.length > 1
+          ? getMetricDisplayName(labelMapValues[0], verboseMap)
+          : MetricDisplayNameA;
       const metricPart: string = showQueryIdentifiers
-        ? `${MetricDisplayNameA} (Query A)`
-        : MetricDisplayNameA;
+        ? `${metricDisplayName} (Query A)`
+        : metricDisplayName;
       displayName = entryName.includes(metricPart)
         ? entryName
         : `${metricPart}, ${entryName}`;
@@ -471,8 +481,6 @@ export default function transformProps(
       // When no groupby, format as just the entry name with optional query identifier
       displayName = showQueryIdentifiers ? `${entryName} (Query A)` : entryName;
     }
-
-    const labelMapValues = rawLabelMap?.[seriesName];
     if (labelMapValues) {
       displayLabelMap[displayName] = labelMapValues;
     }
@@ -536,13 +544,23 @@ export default function transformProps(
     const seriesEntry = inverted[entryName] || entryName;
     const colorScaleKey = getOriginalSeries(seriesEntry, array);
 
+    const labelMapValuesB = rawLabelMapB?.[seriesEntry];
+
     let displayName: string;
 
     if (groupbyB.length > 0) {
-      // When we have groupby, format as "metric, dimension"
+      // When we have groupby, format as "metric, dimension". Each series
+      // belongs to the metric recorded in its label-map tuple
+      // ([metric, ...dimensions]) — always using the first metric would
+      // prepend it to every other metric's series (#37921). Tuples without
+      // a metric part fall back to the first metric as before.
+      const metricDisplayName =
+        labelMapValuesB && labelMapValuesB.length > 1
+          ? getMetricDisplayName(labelMapValuesB[0], verboseMap)
+          : MetricDisplayNameB;
       const metricPart: string = showQueryIdentifiers
-        ? `${MetricDisplayNameB} (Query B)`
-        : MetricDisplayNameB;
+        ? `${metricDisplayName} (Query B)`
+        : metricDisplayName;
       displayName = entryName.includes(metricPart)
         ? entryName
         : `${metricPart}, ${entryName}`;
@@ -550,8 +568,6 @@ export default function transformProps(
       // When no groupby, format as just the entry name with optional query identifier
       displayName = showQueryIdentifiers ? `${entryName} (Query B)` : entryName;
     }
-
-    const labelMapValuesB = rawLabelMapB?.[seriesEntry];
     if (labelMapValuesB) {
       displayLabelMapB[displayName] = labelMapValuesB;
     }

superset-frontend/plugins/plugin-chart-echarts/test/MixedTimeseries/transformProps.test.ts

@@ -1106,3 +1106,82 @@ test('tooltip time grain wiring: chart-level time grain drives the tooltip when
   expect(result).toContain('2021');
   expect(result).not.toContain('2021-01-07');
 });
+
+test('regression #37921: multi-metric Query A with groupby does not duplicate first metric in series names', () => {
+  // Regression test for https://github.com/apache/superset/issues/37921
+  // ("Residual" follow-up to #37055).
+  //
+  // When Query A has multiple metrics + at least one Group By dimension,
+  // the display-name builder in transformProps.ts used to prepend the FIRST
+  // metric's display name to every series that didn't literally contain it:
+  //   name: `${MetricDisplayNameA}, ${entryName}`
+  // For series belonging to the *second* metric, this produced a
+  // cross-contaminated label like `score_one, score_two, A` — the
+  // user-visible "first metric duplicated" symptom in the legend / tooltip.
+  // The fix derives each series' metric from its label-map tuple instead.
+  const multiMetricRows = [
+    {
+      'score_one, A': 1,
+      'score_one, B': 2,
+      'score_two, A': 3,
+      'score_two, B': 4,
+      ds: 599616000000,
+    },
+    {
+      'score_one, A': 5,
+      'score_one, B': 6,
+      'score_two, A': 7,
+      'score_two, B': 8,
+      ds: 599916000000,
+    },
+  ];
+  const multiMetricLabelMap = {
+    ds: ['ds'],
+    'score_one, A': ['score_one', 'A'],
+    'score_one, B': ['score_one', 'B'],
+    'score_two, A': ['score_two', 'A'],
+    'score_two, B': ['score_two', 'B'],
+  };
+
+  const queryAData = createTestQueryData(multiMetricRows, {
+    label_map: multiMetricLabelMap,
+  });
+  // Query B keeps the existing single-metric shape — the bug is on
+  // Query A's path so we just need a valid Query B alongside.
+  const queryBData = createTestQueryData(defaultQueryRows, {
+    label_map: defaultLabelMap,
+  });
+
+  const chartProps = createEchartsTimeseriesTestChartProps<
+    EchartsMixedTimeseriesFormData,
+    EchartsMixedTimeseriesProps
+  >({
+    ...MIXED_TIMESERIES_CHART_PROPS_DEFAULTS,
+    defaultQueriesData: [queryAData, queryBData],
+    formData: {
+      ...formData,
+      metrics: ['score_one', 'score_two'],
+      groupby: ['category'],
+    },
+    queriesData: [queryAData, queryBData],
+  });
+  const transformed = transformProps(chartProps);
+
+  const queryASeriesNames = (transformed.echartOptions.series as any[])
+    .map((s: any) => String(s.name))
+    .filter((n: string) => n.includes('score_'));
+
+  // Each (metric, dim_value) combo from Query A should appear exactly once
+  // with the *correct* metric prefix — not the first-metric-prepended-to-
+  // everything-else form.
+  expect(queryASeriesNames).toContain('score_one, A');
+  expect(queryASeriesNames).toContain('score_one, B');
+  expect(queryASeriesNames).toContain('score_two, A');
+  expect(queryASeriesNames).toContain('score_two, B');
+
+  // And explicitly: no series name should contain *both* metric names —
+  // that's the smoking gun for the duplication bug.
+  for (const name of queryASeriesNames) {
+    expect(name).not.toMatch(/score_one,\s+score_two/);
+  }
+});