diff --git a/src/Usage/Adapter/ClickHouse.php b/src/Usage/Adapter/ClickHouse.php
index c905006..51ca399 100644
--- a/src/Usage/Adapter/ClickHouse.php
+++ b/src/Usage/Adapter/ClickHouse.php
@@ -1436,6 +1436,8 @@ private function getColumnType(string $id, string $type = 'event'): string
             'clientType', 'clientCode', 'clientName', 'clientVersion',
             'clientEngine', 'clientEngineVersion',
             'deviceName', 'deviceBrand', 'deviceModel',
+            // metric-scoped dimensions; small closed value spaces per metric
+            'category', 'outcome',
             'hostname', 'ip',
             // premium geo (lower-cardinality only; city/isp/AS org/connection org
             // are high-cardinality and intentionally fall through to Nullable(String))
diff --git a/src/Usage/Metric.php b/src/Usage/Metric.php
index 6c1eff9..6f93382 100644
--- a/src/Usage/Metric.php
+++ b/src/Usage/Metric.php
@@ -64,6 +64,11 @@ class Metric extends ArrayObject
         // sdk identity
         'sdk', 'sdkVersion',
         'deviceName', 'deviceBrand', 'deviceModel',
+        // metric-scoped: what the row is about, and how it ended.
+        // Named `category`, not `type`: the SQL adapter already writes a `type`
+        // column holding 'event'/'gauge', and a dimension of that name silently
+        // overwrote it through array_merge.
+        'category', 'outcome',
     ];
 
     /**
@@ -670,6 +675,13 @@ public static function getEventSchema(): array
             // sdk identity
             $stringColumn('sdk', 256),
             $stringColumn('sdkVersion', 255),
+            // metric-scoped dimensions. `category` is whatever the metric is
+            // broken down by — a messaging channel, a calling code — and
+            // `outcome` is how the attempt ended. Both are read with `metric`
+            // pinned, so the same column carries different value spaces across
+            // metrics, the way resourceId already carries ids of every kind.
+            $stringColumn('category', 64),
+            $stringColumn('outcome', 32),
             $stringColumn('deviceName', 256),
             $stringColumn('deviceBrand', 256),
             $stringColumn('deviceModel', 255),
@@ -756,6 +768,7 @@ public static function getSchema(): array
     public static function getEventIndexes(): array
     {
         $indexed = [
+            'category', 'outcome',
             'path', 'method', 'status',
             'service', 'resourceType', 'resourceId', 'resourceInternalId',
             'teamId', 'teamInternalId',
@@ -763,7 +776,7 @@ public static function getEventIndexes(): array
             'osName', 'clientType', 'clientName', 'deviceName',
         ];
 
-        $setIndexed = ['status', 'method', 'country', 'service', 'clientType', 'osName'];
+        $setIndexed = ['status', 'method', 'country', 'service', 'clientType', 'osName', 'category', 'outcome'];
 
         return array_map(
             static function (string $col) use ($setIndexed): array {
diff --git a/tests/Usage/Adapter/ClickHouseSchemaTest.php b/tests/Usage/Adapter/ClickHouseSchemaTest.php
index 4829c27..7943dcd 100644
--- a/tests/Usage/Adapter/ClickHouseSchemaTest.php
+++ b/tests/Usage/Adapter/ClickHouseSchemaTest.php
@@ -275,6 +275,7 @@ private function expectedDimAssertions(array $columns, string $type): array
             'connectionUsageType', 'autonomousSystemNumber',
             'sdk', 'sdkVersion',
             'ordinal',
+            'category', 'outcome',
         ];
 
         $baseKey = ['id', 'metric', 'value', 'time', 'tenant'];
diff --git a/tests/Usage/MetricTest.php b/tests/Usage/MetricTest.php
index fa7e3e6..9a0d69d 100644
--- a/tests/Usage/MetricTest.php
+++ b/tests/Usage/MetricTest.php
@@ -617,6 +617,7 @@ public function testEventColumnsConstant(): void
             'clientEngine', 'clientEngineVersion',
             'sdk', 'sdkVersion',
             'deviceName', 'deviceBrand', 'deviceModel',
+            'category', 'outcome',
         ];
         $this->assertSame($expected, Metric::EVENT_COLUMNS);
     }