fix: cache explicitly on validator object

Author: iloveagent57

docs/stripe-billing-architecture.md

@@ -0,0 +1,52 @@
+# Stripe Billing Architecture
+
+## Overview
+
+Enterprise Access acts as the **billing orchestrator** in the edX enterprise ecosystem, translating Stripe payment events into business actions across multiple services.
+
+## Architecture Flow
+
+```
+Stripe Billing → Enterprise Access → License Manager → Other Services
+    Events         CheckoutIntents     SubscriptionPlans
+                   + Webhooks          + Licenses
+```
+
+## Key Components
+
+### Enterprise Access (This Service)
+- **CheckoutIntent**: Tracks self-service checkout lifecycle (CREATED → PAID → FULFILLED)
+- **StripeEventHandler**: Processes Stripe webhooks and updates CheckoutIntent state
+- **StripeEventData**: Persists all Stripe events for audit trail
+- **Provisioning Workflows**: Multi-step processes that create business records
+
+### Stripe Integration
+- Webhooks send events to Enterprise Access (`/webhooks/stripe/`)
+- Events like `invoice.paid`, `customer.subscription.updated` trigger handlers
+- Each event is persisted and linked to relevant CheckoutIntent
+
+### License Manager Integration
+- Enterprise Access makes REST API calls to License Manager
+- `CheckoutIntent.quantity` maps 1:1 to `SubscriptionPlan.num_licenses`
+- `CheckoutIntent.enterprise_uuid` links to License Manager's `CustomerAgreement`
+
+## Typical Flow
+
+1. **Customer pays** → Stripe sends `invoice.paid` webhook
+2. **Enterprise Access** receives webhook, marks CheckoutIntent as PAID
+3. **Provisioning workflow** triggered, creates enterprise customer
+4. **API calls** to License Manager create SubscriptionPlan + Licenses
+5. **Customer** can now assign licenses to learners
+
+## Key Models
+
+- **CheckoutIntent**: Central billing state machine
+- **StripeEventData**: Complete audit trail of Stripe events
+- **ProvisioningWorkflow**: Orchestrates cross-service business record creation
+
+## Why This Design?
+
+- **Single source of truth** for billing events
+- **Reliable event processing** with persistence and retry capabilities
+- **Clean separation** between billing (Enterprise Access) and licensing (License Manager)
+- **Audit trail** for compliance and debugging

enterprise_access/apps/customer_billing/api.py

@@ -3,7 +3,6 @@
 """
 import logging
 from collections.abc import Mapping
-from functools import cache
 from typing import TypedDict, Unpack, cast
 
 import stripe
@@ -56,8 +55,6 @@ class FieldValidationResult(TypedDict):
     developer_message: str | None
 
 
-# Basic in-memory cache to prevent multiple API calls within a single request.
-@cache
 def _get_lms_user_id(email: str | None) -> int | None:
     """
     Return the LMS user ID for an existing user with a specific email, or None if no user with that email exists.
@@ -80,6 +77,11 @@ class CheckoutSessionInputValidator():
     https://github.com/openedx/edx-platform/blob/f90e59e5/openedx/core/djangoapps/user_authn/views/register.py#L727
     """
 
+    def get_lms_user_id(self, email):
+        if not hasattr(self, '_cached_lms_user_id'):
+            self._cached_lms_user_id = _get_lms_user_id(email)  # pylint: disable=attribute-defined-outside-init
+        return self._cached_lms_user_id
+
     def handle_admin_email(self, input_data: CheckoutSessionInputValidatorData) -> FieldValidationResult:
         """
         Ensure the provided email is registered.
@@ -103,7 +105,7 @@ def handle_admin_email(self, input_data: CheckoutSessionInputValidatorData) -> F
             return {'error_code': error_code, 'developer_message': developer_message}
 
         # Given email must be registered.
-        lms_user_id = _get_lms_user_id(email=admin_email)
+        lms_user_id = self.get_lms_user_id(email=admin_email)
         if not lms_user_id:
             error_code, developer_message = CHECKOUT_SESSION_ERROR_CODES['admin_email']['NOT_REGISTERED']
             logger.info(f'admin_email invalid: "{admin_email}". {developer_message}')
@@ -276,7 +278,7 @@ def handle_user(self, input_data: CheckoutSessionInputValidatorData) -> FieldVal
           **and** the lms_user_id is known and present in the User table.
         """
         if not (user_record := input_data.get('user')):
-            lms_user_id = _get_lms_user_id(input_data.get('admin_email'))
+            lms_user_id = self.get_lms_user_id(input_data.get('admin_email'))
             user_record = User.objects.filter(lms_user_id=lms_user_id).first()
             if not user_record:
                 error_code, developer_message = CHECKOUT_SESSION_ERROR_CODES['user']['IS_NULL']

enterprise_access/apps/customer_billing/apps.py

@@ -4,8 +4,9 @@
 
 
 class CustomerBillingConfig(AppConfig):
+    """ App config for customer_billing. """
     default_auto_field = 'django.db.models.BigAutoField'
     name = 'enterprise_access.apps.customer_billing'
 
     def ready(self):
-        import enterprise_access.apps.customer_billing.signals  # noqa
+        import enterprise_access.apps.customer_billing.signals  # pylint: disable=import-outside-toplevel,unused-import

enterprise_access/apps/customer_billing/tests/test_api.py

@@ -76,7 +76,6 @@ def setUp(self):
         self.other_user = UserFactory()
 
     def tearDown(self):
-        customer_billing_api._get_lms_user_id.cache_clear()  # pylint: disable=protected-access
         # Clean up any intents created during tests
         CheckoutIntent.objects.all().delete()