diff --git a/heicode/model/task_cas_test.go b/heicode/model/task_cas_test.go
index 79ae8c96..5109c60e 100644
--- a/heicode/model/task_cas_test.go
+++ b/heicode/model/task_cas_test.go
@@ -43,6 +43,7 @@ func TestMain(m *testing.M) {
 		&SubscriptionPlan{},
 		&SubscriptionOrder{},
 		&UserSubscription{},
+		&TelemetryEvent{},
 	); err != nil {
 		panic("failed to migrate: " + err.Error())
 	}
diff --git a/heicode/model/telemetry_retention_test.go b/heicode/model/telemetry_retention_test.go
new file mode 100644
index 00000000..57190e3b
--- /dev/null
+++ b/heicode/model/telemetry_retention_test.go
@@ -0,0 +1,38 @@
+package model
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+// #43: the retention purge must delete telemetry rows received before the
+// cutoff and leave newer rows intact. TelemetryEvent is migrated by the package
+// TestMain; LOG_DB == DB in tests.
+func TestDeleteTelemetryEventsBefore(t *testing.T) {
+	// Isolate from any other test's rows.
+	require.NoError(t, LOG_DB.Where("1 = 1").Delete(&TelemetryEvent{}).Error)
+
+	mk := func(receivedAt int64, client string) {
+		require.NoError(t, LOG_DB.Create(&TelemetryEvent{
+			ReceivedAt: receivedAt, UserId: 1, ClientId: client, SchemaVersion: 1,
+		}).Error)
+	}
+	mk(1000, "old-1")  // before cutoff -> deleted
+	mk(2999, "old-2")  // before cutoff -> deleted
+	mk(3000, "keep-1") // == cutoff -> kept (strict <)
+	mk(5000, "keep-2") // after cutoff -> kept
+
+	deleted, err := DeleteTelemetryEventsBefore(3000)
+	require.NoError(t, err)
+	require.EqualValues(t, 2, deleted, "rows with received_at < cutoff are purged")
+
+	var remaining int64
+	require.NoError(t, LOG_DB.Model(&TelemetryEvent{}).Count(&remaining).Error)
+	require.EqualValues(t, 2, remaining, "rows at/after cutoff are retained")
+
+	// Idempotent: a second pass with the same cutoff deletes nothing.
+	again, err := DeleteTelemetryEventsBefore(3000)
+	require.NoError(t, err)
+	require.EqualValues(t, 0, again)
+}