add access_expires_at to enrollment

enrollments-events/app/enrollment.py

@@ -1,3 +1,4 @@
+from datetime import timedelta
 from typing import NotRequired, Self, TypedDict
 
 from layercake.dateutils import now, ttl
@@ -48,12 +49,14 @@ def enroll(
     user = enrollment.user
     course = enrollment.course
     lock_hash = md5_hash('%s%s' % (user.id, course.id))
+    access_expires_at = now_ + timedelta(days=course.access_period)
 
     with persistence_layer.transact_writer() as transact:
         transact.put(
             item={
                 'sk': '0',
                 'created_at': now_,
+                'access_expires_at': access_expires_at,
                 **enrollment.model_dump(),
             }
             | ({'subscription_covered': True} if subscription else {})