Implement an Adobe Commerce (Magento 2) custom REST API endpoint with authentication and rate limiting for a headless B2B mobile app

Verified steps

1. Define a custom REST API endpoint in a Magento 2 module by configuring the webapi.xml file with the route, HTTP method, service interface, method, and required ACL resources
2. Implement the service interface and its concrete class with business logic, injecting the required repositories and factories via constructor dependency injection
3. Add the ACL resource definition to acl.xml so the endpoint permission can be assigned to specific API roles in the Magento admin, restricting access to authorized B2B customer tokens
4. Generate a customer token using the existing Magento token endpoint and pass it as a Bearer token in subsequent requests to authenticate against the custom endpoint using the standard Magento token authentication middleware
5. Implement request rate limiting by wrapping the service method with a custom plugin that checks a Redis counter keyed by the customer ID and returns a 429 response when the per-minute threshold is exceeded
6. Write integration tests using the Magento testing framework's REST API test base class to verify authentication enforcement, input validation, and correct response schemas before deploying to production