diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8978a2f..f01de9a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,18 @@
 # Changelog
 
+## 0.11.0 — sdk dimensions
+
+### Added
+
+- Two event-only SDK dimensions in `Metric::EVENT_COLUMNS` and
+  `Metric::getEventSchema()`: `sdk` (originating SDK name, e.g.
+  `web`, `flutter`, `console`, `cli`) and `sdkVersion` (e.g.
+  `14.0.0`). Both are optional strings. In ClickHouse both map to
+  `LowCardinality(Nullable(String))` with `CODEC(ZSTD(3))`. Existing
+  tables auto-materialize the columns on `setup()` via the
+  `ADD COLUMN IF NOT EXISTS` path. Gauges are unchanged; these columns
+  are not added to the primary key or indexes.
+
 ## 0.10.0 — premium geo dimensions
 
 ### Added
diff --git a/src/Usage/Adapter/ClickHouse.php b/src/Usage/Adapter/ClickHouse.php
index a1f383f..8460166 100644
--- a/src/Usage/Adapter/ClickHouse.php
+++ b/src/Usage/Adapter/ClickHouse.php
@@ -1213,6 +1213,8 @@ private function getColumnType(string $id, string $type = 'event'): string
             // are high-cardinality and intentionally fall through to Nullable(String))
             'continentCode', 'subdivisions', 'connectionType',
             'connectionUsageType', 'autonomousSystemNumber',
+            // sdk identity
+            'sdk', 'sdkVersion',
         ];
 
         if (in_array($id, $lowCardinality, true)) {
@@ -1256,6 +1258,7 @@ private function getColumnCodec(string $id): string
             'city', 'continentCode', 'subdivisions', 'isp',
             'autonomousSystemNumber', 'autonomousSystemOrganization',
             'connectionType', 'connectionUsageType', 'connectionOrganization',
+            'sdk', 'sdkVersion',
         ];
 
         if (in_array($id, $zstdColumns, true)) {
diff --git a/src/Usage/Metric.php b/src/Usage/Metric.php
index 734a674..416efcc 100644
--- a/src/Usage/Metric.php
+++ b/src/Usage/Metric.php
@@ -61,6 +61,8 @@ class Metric extends ArrayObject
         'osCode', 'osName', 'osVersion',
         'clientType', 'clientCode', 'clientName', 'clientVersion',
         'clientEngine', 'clientEngineVersion',
+        // sdk identity
+        'sdk', 'sdkVersion',
         'deviceName', 'deviceBrand', 'deviceModel',
     ];
 
@@ -92,6 +94,7 @@ class Metric extends ArrayObject
      * - osCode / osName / osVersion: parsed user-agent OS fields
      * - clientType / clientCode / clientName / clientVersion: parsed client
      * - clientEngine / clientEngineVersion: parsed client engine
+     * - sdk / sdkVersion: originating SDK name and version
      * - deviceName / deviceBrand / deviceModel: parsed device fields
      *
      * Gauge-only dimension columns (see GAUGE_COLUMNS):
@@ -654,6 +657,9 @@ public static function getEventSchema(): array
             $stringColumn('clientVersion', 255),
             $stringColumn('clientEngine', 256),
             $stringColumn('clientEngineVersion', 255),
+            // sdk identity
+            $stringColumn('sdk', 256),
+            $stringColumn('sdkVersion', 255),
             $stringColumn('deviceName', 256),
             $stringColumn('deviceBrand', 256),
             $stringColumn('deviceModel', 255),
diff --git a/tests/Usage/Adapter/ClickHouseColumnTypeTest.php b/tests/Usage/Adapter/ClickHouseColumnTypeTest.php
index a56e7a6..834015e 100644
--- a/tests/Usage/Adapter/ClickHouseColumnTypeTest.php
+++ b/tests/Usage/Adapter/ClickHouseColumnTypeTest.php
@@ -72,4 +72,18 @@ public function testHighCardinalityPremiumGeoColumns(): void
             );
         }
     }
+
+    /**
+     * SDK dims must map to LowCardinality(Nullable(String)).
+     */
+    public function testLowCardinalitySdkColumns(): void
+    {
+        foreach (['sdk', 'sdkVersion'] as $col) {
+            $this->assertSame(
+                'LowCardinality(Nullable(String))',
+                $this->columnType($col),
+                "{$col} should be LowCardinality(Nullable(String))"
+            );
+        }
+    }
 }
diff --git a/tests/Usage/Adapter/ClickHouseSchemaTest.php b/tests/Usage/Adapter/ClickHouseSchemaTest.php
index 01c2339..94e8618 100644
--- a/tests/Usage/Adapter/ClickHouseSchemaTest.php
+++ b/tests/Usage/Adapter/ClickHouseSchemaTest.php
@@ -51,6 +51,10 @@ public function testEventsTableCarriesCodecsAndLowCardinality(): void
         $this->assertStringContainsString('`connectionType` LowCardinality(Nullable(String)) CODEC(ZSTD(3))', $ddl);
         $this->assertStringContainsString('`city` Nullable(String) CODEC(ZSTD(3))', $ddl);
         $this->assertStringContainsString('`isp` Nullable(String) CODEC(ZSTD(3))', $ddl);
+
+        // sdk: both dims are low-cardinality.
+        $this->assertStringContainsString('`sdk` LowCardinality(Nullable(String)) CODEC(ZSTD(3))', $ddl);
+        $this->assertStringContainsString('`sdkVersion` LowCardinality(Nullable(String)) CODEC(ZSTD(3))', $ddl);
     }
 
     public function testEventsTableSwapsBloomForSetOnLowCardinality(): void
@@ -264,6 +268,7 @@ private function expectedDimAssertions(array $columns, string $type): array
             'hostname', 'ip',
             'continentCode', 'subdivisions', 'connectionType',
             'connectionUsageType', 'autonomousSystemNumber',
+            'sdk', 'sdkVersion',
         ];
 
         $baseKey = ['id', 'metric', 'value', 'time', 'tenant'];
diff --git a/tests/Usage/MetricTest.php b/tests/Usage/MetricTest.php
index b27a2d2..718b148 100644
--- a/tests/Usage/MetricTest.php
+++ b/tests/Usage/MetricTest.php
@@ -615,6 +615,7 @@ public function testEventColumnsConstant(): void
             'osCode', 'osName', 'osVersion',
             'clientType', 'clientCode', 'clientName', 'clientVersion',
             'clientEngine', 'clientEngineVersion',
+            'sdk', 'sdkVersion',
             'deviceName', 'deviceBrand', 'deviceModel',
         ];
         $this->assertSame($expected, Metric::EVENT_COLUMNS);
@@ -681,6 +682,35 @@ public function testPremiumGeoColumnsArePresentAsEventStrings(): void
         }
     }
 
+    /**
+     * The sdk dimensions are event-only string columns that are present in
+     * EVENT_COLUMNS and the event schema (as non-required strings) but never
+     * leak into the gauge column set.
+     */
+    public function testSdkColumnsArePresentAsEventStrings(): void
+    {
+        $sdk = ['sdk', 'sdkVersion'];
+
+        $schema = Metric::getEventSchema();
+        $eventIds = array_column($schema, '$id');
+        $gaugeIds = array_column(Metric::getGaugeSchema(), '$id');
+
+        foreach ($sdk as $col) {
+            $this->assertContains($col, Metric::EVENT_COLUMNS, "EVENT_COLUMNS missing {$col}");
+            $this->assertContains($col, $eventIds, "Event schema missing {$col}");
+            $this->assertNotContains($col, Metric::GAUGE_COLUMNS, "{$col} must be event-only");
+            $this->assertNotContains($col, $gaugeIds, "{$col} must not be in gauge schema");
+
+            $matches = array_values(array_filter(
+                $schema,
+                static fn (array $attr): bool => $attr['$id'] === $col,
+            ));
+            $this->assertCount(1, $matches, "{$col} must appear exactly once");
+            $this->assertSame('string', $matches[0]['type'], "{$col} must be a string column");
+            $this->assertFalse($matches[0]['required'], "{$col} must be optional");
+        }
+    }
+
     /**
      * Test that the gauge schema contains the new team and resource id columns.
      */