diff --git a/prisma/migrations/20261106140000_device_primary_key/migration.sql b/prisma/migrations/20261106140000_device_primary_key/migration.sql
new file mode 100644
index 0000000..779e3d4
--- /dev/null
+++ b/prisma/migrations/20261106140000_device_primary_key/migration.sql
@@ -0,0 +1,4 @@
+-- Device.id becomes the primary key. The existing unique index on "id" is
+-- reused, so Postgres renames it to "Device_pkey" without rebuilding it. The
+-- column is already NOT NULL, so no table scan is needed.
+ALTER TABLE "Device" ADD CONSTRAINT "Device_pkey" PRIMARY KEY USING INDEX "Device_id_key";
diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index 493b1cc..e87b36d 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -23,7 +23,7 @@ model User {
 }
 
 model Device {
-  id                 String    @unique
+  id                 String    @id
   lastSeen           DateTime? @db.Timestamp(6)
   name               String?
   user               User      @relation(fields: [userId], references: [id])