diff --git a/app/Scopes/TenantScope.php b/app/Scopes/TenantScope.php
new file mode 100644
index 0000000..4c7e15d
--- /dev/null
+++ b/app/Scopes/TenantScope.php
@@ -0,0 +1,28 @@
+<?php
+
+namespace App\Scopes;
+
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Scope;
+
+class TenantScope implements Scope
+{
+    public function apply(Builder $builder, Model $model): void
+    {
+        $user = auth()->user();
+
+        if ($user === null) {
+            // Default-deny: null-user must NEVER silently see all records
+            // (prevents leaks in queue jobs, Tinker, etc.)
+            $builder->whereRaw('0 = 1');
+            return;
+        }
+
+        if ($user->hasRole('platform-admin')) {
+            return; // platform-admin sees all tenants
+        }
+
+        $builder->where($model->getTable() . '.tenant_id', $user->tenant_id);
+    }
+}
diff --git a/app/Traits/BelongsToTenant.php b/app/Traits/BelongsToTenant.php
new file mode 100644
index 0000000..aca57d7
--- /dev/null
+++ b/app/Traits/BelongsToTenant.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace App\Traits;
+
+use App\Scopes\TenantScope;
+
+trait BelongsToTenant
+{
+    protected static function bootBelongsToTenant(): void
+    {
+        static::addGlobalScope(new TenantScope());
+
+        static::creating(function ($model) {
+            $user = auth()->user();
+            if ($user && !$user->hasRole('platform-admin')) {
+                // Force tenant_id — prevents cross-tenant mass-assign attacks
+                $model->tenant_id = $user->tenant_id;
+            }
+        });
+    }
+}
diff --git a/app/Traits/HasUuid.php b/app/Traits/HasUuid.php
new file mode 100644
index 0000000..a6a1942
--- /dev/null
+++ b/app/Traits/HasUuid.php
@@ -0,0 +1,20 @@
+<?php
+
+namespace App\Traits;
+
+use Illuminate\Support\Str;
+
+trait HasUuid
+{
+    protected static function bootHasUuid(): void
+    {
+        static::creating(function ($model) {
+            $model->uuid ??= (string) Str::uuid();
+        });
+    }
+
+    public function getRouteKeyName(): string
+    {
+        return 'uuid';
+    }
+}
diff --git a/tests/Pest.php b/tests/Pest.php
index b9fb6f7..f6eb1db 100644
--- a/tests/Pest.php
+++ b/tests/Pest.php
@@ -22,6 +22,9 @@ pest()->extend(TestCase::class)
  // ->use(RefreshDatabase::class)
     ->in('Feature');
 
+pest()->extend(TestCase::class)
+    ->in('Unit');
+
 /*
 |--------------------------------------------------------------------------
 | Expectations
diff --git a/tests/Unit/Models/HasUuidTest.php b/tests/Unit/Models/HasUuidTest.php
new file mode 100644
index 0000000..33b49dc
--- /dev/null
+++ b/tests/Unit/Models/HasUuidTest.php
@@ -0,0 +1,16 @@
+<?php
+
+use App\Models\User;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+
+uses(RefreshDatabase::class);
+
+it('generiert UUID beim Erstellen eines Users', function () {
+    $user = User::factory()->create();
+    expect($user->uuid)->toMatch('/^[0-9a-f-]{36}$/');
+});
+
+it('nutzt UUID als Route-Key', function () {
+    $user = User::factory()->create();
+    expect($user->getRouteKeyName())->toBe('uuid');
+});