diff --git a/apps/api/src/agents/tools/base.ts b/apps/api/src/agents/tools/base.ts
index 576ae2970..22039d31e 100644
--- a/apps/api/src/agents/tools/base.ts
+++ b/apps/api/src/agents/tools/base.ts
@@ -258,7 +258,15 @@ export const generateReport = chatTool(
         )
         .default([])
         .optional(),
-      metric: z.enum(['sum', 'count', 'average']).default('sum').optional(),
+      // No `.default()` here on purpose: it would make an omitted metric
+      // indistinguishable from an explicit `sum`, and the fallback depends on
+      // the chart type (see below).
+      metric: z
+        .enum(['sum', 'count', 'average', 'min', 'max'])
+        .optional()
+        .describe(
+          'How a series is aggregated for display. Only the metric and map chart types read this; `count` is unique profiles. Omit it unless the user asked for a specific aggregation — metric cards then default to unique profiles.',
+        ),
       previous: z
         .boolean()
         .optional()
@@ -338,7 +346,11 @@ export const generateReport = chatTool(
         }),
       ),
       range: 'custom' as const,
-      metric: input.metric ?? 'sum',
+      // A metric card has always shown the total unique count, so an
+      // unspecified metric must stay `count` there — `sum` would silently turn
+      // "1.2k users" into "45k events".
+      metric:
+        input.metric ?? (input.chartType === 'metric' ? 'count' : 'sum'),
       previous: input.previous ?? false,
       ...(input.lineType ? { lineType: input.lineType } : {}),
       ...(input.limit ? { limit: input.limit } : {}),
diff --git a/apps/start/src/components/report-chart/metric/chart.tsx b/apps/start/src/components/report-chart/metric/chart.tsx
index 8d5a96c1b..c37dca3eb 100644
--- a/apps/start/src/components/report-chart/metric/chart.tsx
+++ b/apps/start/src/components/report-chart/metric/chart.tsx
@@ -12,7 +12,7 @@ interface Props {
 export function Chart({ data }: Props) {
   const {
     isEditMode,
-    report: { unit },
+    report: { metric, unit },
   } = useReportChartContext();
   const { series } = useVisibleSeries(data, { limit: isEditMode ? 20 : 4 });
   return (
@@ -27,7 +27,7 @@ export function Chart({ data }: Props) {
           <MetricCard
             key={serie.id}
             serie={serie}
-            metric={'count'}
+            metric={metric}
             unit={unit}
           />
         );
diff --git a/apps/start/src/components/report-chart/metric/metric-card.tsx b/apps/start/src/components/report-chart/metric/metric-card.tsx
index 334091bfc..e98b1d63d 100644
--- a/apps/start/src/components/report-chart/metric/metric-card.tsx
+++ b/apps/start/src/components/report-chart/metric/metric-card.tsx
@@ -58,7 +58,11 @@ export function MetricCard({
   const number = useNumber();
 
   const renderValue = (value: number | undefined, unitClassName?: string) => {
-    if (!value) {
+    // A genuine 0 is a real value, not a missing one — `min` is 0 whenever the
+    // range contains an empty bucket. Only absent metrics render as N/A, which
+    // still matters: getAggregateChartSql never selects total_count, so `count`
+    // really is undefined for bar/pie series.
+    if (value === undefined || value === null) {
       return <div className="text-muted-foreground">N/A</div>;
     }
 
diff --git a/apps/start/src/components/report/reportSlice.ts b/apps/start/src/components/report/reportSlice.ts
index 9f88a1eb8..87df79de7 100644
--- a/apps/start/src/components/report/reportSlice.ts
+++ b/apps/start/src/components/report/reportSlice.ts
@@ -13,6 +13,7 @@ import type {
   IChartEventFilter,
   IChartEventItem,
   IChartLineType,
+  IChartMetric,
   IChartRange,
   IChartType,
   IInterval,
@@ -209,6 +210,14 @@ export const reportSlice = createSlice({
       state.dirty = true;
       state.chartType = action.payload;
 
+      // The Metric card has always shown the total unique count. Existing
+      // reports are backfilled to 'count' by migration, so default a newly
+      // switched one the same way rather than leaving old and new metric
+      // reports showing different aggregations. The picker overrides it.
+      if (action.payload === 'metric') {
+        state.metric = 'count';
+      }
+
       // Initialize sankey options if switching to sankey
       if (action.payload === 'sankey' && !state.options) {
         state.options = {
@@ -301,6 +310,11 @@ export const reportSlice = createSlice({
       state.unit = action.payload || undefined;
     },
 
+    changeMetric(state, action: PayloadAction<IChartMetric>) {
+      state.dirty = true;
+      state.metric = action.payload;
+    },
+
     changeFunnelGroup(state, action: PayloadAction<string | undefined>) {
       state.dirty = true;
       if (!state.options || state.options.type !== 'funnel') {
@@ -445,6 +459,7 @@ export const {
   changePrevious,
   changeCriteria,
   changeUnit,
+  changeMetric,
   changeFunnelGroup,
   changeFunnelWindow,
   changeOptions,
diff --git a/apps/start/src/components/report/sidebar/ReportSettings.tsx b/apps/start/src/components/report/sidebar/ReportSettings.tsx
index 7f12ce348..777a93d28 100644
--- a/apps/start/src/components/report/sidebar/ReportSettings.tsx
+++ b/apps/start/src/components/report/sidebar/ReportSettings.tsx
@@ -7,11 +7,13 @@ import { Label } from '@/components/ui/label';
 import { Switch } from '@/components/ui/switch';
 import { useAppParams } from '@/hooks/use-app-params';
 import { useEventNames } from '@/hooks/use-event-names';
+import type { IChartMetric } from '@openpanel/validation';
 import { useMemo } from 'react';
 import {
   changeCriteria,
   changeFunnelGroup,
   changeFunnelWindow,
+  changeMetric,
   changePrevious,
   changeSankeyExclude,
   changeSankeyInclude,
@@ -25,6 +27,7 @@ export function ReportSettings() {
   const chartType = useSelector((state) => state.report.chartType);
   const previous = useSelector((state) => state.report.previous);
   const unit = useSelector((state) => state.report.unit);
+  const metric = useSelector((state) => state.report.metric);
   const options = useSelector((state) => state.report.options);
 
   const retentionOptions = options?.type === 'retention' ? options : undefined;
@@ -69,6 +72,11 @@ export function ReportSettings() {
       fields.push('stacked');
     }
 
+    // `map` already reads report.metric; it just never had a way to set it.
+    if (chartType === 'metric' || chartType === 'map') {
+      fields.push('metric');
+    }
+
     return fields;
   }, [chartType]);
 
@@ -137,6 +145,27 @@ export function ReportSettings() {
             />
           </div>
         )}
+        {fields.includes('metric') && (
+          <div className="flex items-center justify-between gap-4">
+            <Label className="whitespace-nowrap font-medium mb-0">
+              Aggregation
+            </Label>
+            <Combobox
+              align="end"
+              placeholder="Aggregation"
+              value={metric}
+              onChange={(val) => dispatch(changeMetric(val as IChartMetric))}
+              // Same labels the report table uses for these columns.
+              items={[
+                { label: 'Unique', value: 'count' },
+                { label: 'Sum', value: 'sum' },
+                { label: 'Average', value: 'average' },
+                { label: 'Min', value: 'min' },
+                { label: 'Max', value: 'max' },
+              ]}
+            />
+          </div>
+        )}
         {fields.includes('funnelGroup') && (
           <div className="flex items-center justify-between gap-4">
             <Label className="whitespace-nowrap font-medium mb-0">
diff --git a/packages/db/prisma/migrations/20260818090000_add_count_to_metric_enum/migration.sql b/packages/db/prisma/migrations/20260818090000_add_count_to_metric_enum/migration.sql
new file mode 100644
index 000000000..d9a0994fa
--- /dev/null
+++ b/packages/db/prisma/migrations/20260818090000_add_count_to_metric_enum/migration.sql
@@ -0,0 +1,8 @@
+-- Metric charts have always rendered the total unique count, but `count` had no
+-- home in the enum, so `report.create`/`report.update` silently rewrote it to
+-- `sum`. Add the value so a picked aggregation can actually persist.
+--
+-- This must be its own migration: Postgres refuses to use a new enum value in
+-- the same transaction that added it ("unsafe use of new value ... of enum
+-- type Metric"). The backfill lives in the next migration.
+ALTER TYPE "Metric" ADD VALUE 'count';
diff --git a/packages/db/prisma/migrations/20260818090100_backfill_metric_reports_to_count/migration.sql b/packages/db/prisma/migrations/20260818090100_backfill_metric_reports_to_count/migration.sql
new file mode 100644
index 000000000..c5f13f72b
--- /dev/null
+++ b/packages/db/prisma/migrations/20260818090100_backfill_metric_reports_to_count/migration.sql
@@ -0,0 +1,8 @@
+-- Every existing metric-type report stores 'sum' because the column is
+-- NOT NULL DEFAULT 'sum' and nothing ever wrote anything else — the value was
+-- read by nothing, since the SQL builders ignore `metric` and the Metric card
+-- hardcoded 'count'. Now that the card honours the stored value, leaving them
+-- at 'sum' would flip every existing tile from unique-users to summed events.
+--
+-- Lossless: for chartType = 'metric' the stored value carried no user intent.
+UPDATE "reports" SET "metric" = 'count' WHERE "chartType" = 'metric';
diff --git a/packages/db/prisma/schema.prisma b/packages/db/prisma/schema.prisma
index 8e9fe979d..10b219161 100644
--- a/packages/db/prisma/schema.prisma
+++ b/packages/db/prisma/schema.prisma
@@ -378,6 +378,9 @@ enum Metric {
   average
   min
   max
+  // Appended last to match what `ALTER TYPE ... ADD VALUE` does in the DB,
+  // so `prisma migrate` reports no drift.
+  count
 }
 
 model Report {
diff --git a/packages/trpc/src/routers/report.ts b/packages/trpc/src/routers/report.ts
index 2ba31ced3..a876a4c2f 100644
--- a/packages/trpc/src/routers/report.ts
+++ b/packages/trpc/src/routers/report.ts
@@ -65,7 +65,7 @@ export const reportRouter = createTRPCRouter({
           formula: report.formula,
           previous: report.previous ?? false,
           unit: report.unit,
-          metric: report.metric === 'count' ? 'sum' : report.metric,
+          metric: report.metric,
           options: report.options,
           visibleSeries: report.visibleSeries ?? [],
           startDate: report.range === 'custom' ? report.startDate : null,
@@ -112,7 +112,7 @@ export const reportRouter = createTRPCRouter({
           formula: report.formula,
           previous: report.previous ?? false,
           unit: report.unit,
-          metric: report.metric === 'count' ? 'sum' : report.metric,
+          metric: report.metric,
           options: report.options,
           visibleSeries: report.visibleSeries ?? [],
           startDate: report.range === 'custom' ? report.startDate : null,