add purge to canceled and failed enrollment

enrollments-events/app/enrollment.py

@@ -61,6 +61,8 @@ Org = TypedDict('Org', {'org_id': str, 'name': str})
 
 CreatedBy = TypedDict('CreatedBy', {'id': str, 'name': str})
 
+Seat = TypedDict('Seat', {'id': str, 'sk': str})
+
 DeduplicationWindow = TypedDict('DeduplicationWindow', {'offset_days': int})
 
 Subscription = TypedDict(
@@ -100,6 +102,11 @@ class SubscriptionFrozenError(Exception):
         super().__init__('Subscription is frozen')
 
 
+class SeatNotFoundError(Exception):
+    def __init__(self, msg: str | dict):
+        super().__init__('Seat required')
+
+
 def enroll(
     enrollment: Enrollment,
     *,
@@ -108,6 +115,7 @@ def enroll(
     subscription: Subscription | None = None,
     created_by: CreatedBy | None = None,
     scheduled_at: datetime | None = None,
+    seat: Seat | None = None,
     linked_entities: frozenset[LinkedEntity] = frozenset(),
     deduplication_window: DeduplicationWindow | None = None,
     persistence_layer: DynamoDBPersistenceLayer,
@@ -138,6 +146,8 @@ def enroll(
                     'sk': 'CANCEL_POLICY',
                     'created_at': now_,
                 }
+                #
+                | ({'seat': seat} if seat else {})
             )
 
         # Relationships between this enrollment and its related entities